Mobile electronics every year, if not month, becomes more accessible and widespread. Here you have laptops, PDAs, digital cameras, mobile phones, and a lot of other useful and not-so-useful devices. And all of these devices are continually gaining new features, more powerful processors, larger color screens, wireless connectivity, while shrinking in size. But, unlike semiconductor technologies, the power technologies of this mobile menagerie are not at all by leaps and bounds.

Conventional rechargeable batteries and batteries are clearly not enough to power the latest advances in the electronics industry for any significant time. And without reliable, high-capacity batteries, the whole point of mobility and wirelessness is lost. So the computer industry is more and more actively working on the problem alternative power supplies... And the most promising direction here today is fuel cells.

The basic principle of fuel cells was discovered by the British scientist Sir William Grove in 1839. He is known as the father of the "fuel cell". William Grove generated electricity by alteration to extract hydrogen and oxygen. Disconnecting the battery from the electrolytic cell, Grove was surprised to find that the electrodes began to absorb the evolved gas and generate current. Opening a process electrochemical "cold" combustion of hydrogen became a significant event in the energy sector, and later such well-known electrochemists as Ostwald and Nernst played an important role in the development theoretical foundations and the practical implementation of fuel cells and predicted a great future for them.

Myself the term "fuel cell" appeared later - it was proposed in 1889 by Ludwig Mond and Charles Langer, who were trying to create a device for generating electricity from air and coal gas.

In normal combustion in oxygen, organic fuel is oxidized, and the chemical energy of the fuel is inefficiently converted into thermal energy. But it turned out to be possible for the oxidation reaction, for example, of hydrogen with oxygen, to be carried out in an electrolyte environment and, in the presence of electrodes, to obtain an electric current. For example, supplying hydrogen to an electrode in an alkaline medium, we get electrons:

2H2 + 4OH- → 4H2O + 4e-

which, passing through the external circuit, enter the opposite electrode, to which oxygen enters and where the reaction takes place: 4e- + O2 + 2H2O → 4OH-

It can be seen that the resulting reaction 2H2 + O2 → H2O is the same as in conventional combustion, but in a fuel cell, or otherwise - in electrochemical generator, an electric current is obtained with great efficiency and partly heat. Note that coal, carbon monoxide, alcohols, hydrazine, and other organic substances can also be used as fuel in fuel cells, and air, hydrogen peroxide, chlorine, bromine, nitric acid, etc. can be used as oxidants.

The development of fuel cells continued vigorously both abroad and in Russia, and then in the USSR. Among the scientists who have made a great contribution to the study of fuel cells, we note V. Jaco, P. Yablochkov, F. Bacon, E. Bauer, E. Yusti, K. Kordesh. In the middle of the last century, a new storm of fuel cell problems began. This is partly due to the emergence of new ideas, materials and technologies as a result of defense research.

One of the scientists who made a major step in the development of fuel cells was P.M.Spiridonov. Spiridonov's hydrogen-oxygen elements gave a current density of 30 mA / cm2, which for that time was considered a great achievement. In the forties O. Davtyan created an installation for electrochemical combustion of generator gas obtained by coal gasification. For each cubic meter of the element volume, Davtyan received 5 kW of power.

It was the first solid electrolyte fuel cell... It had a high efficiency, but over time the electrolyte deteriorated and had to be changed. Subsequently, Davtyan at the end of the fifties created a powerful installation that sets the tractor in motion. In the same years, the English engineer T. Bacon designed and built a battery of fuel cells with a total capacity of 6 kW and an efficiency of 80%, operating on pure hydrogen and oxygen, but the power-to-weight ratio of the battery turned out to be too small - such cells were unsuitable for practical use and too expensive.

In the years that followed, the time of loners passed. The creators are interested in fuel cells spacecraft... Since the mid-60s, millions of dollars have been invested in fuel cell research. The work of thousands of scientists and engineers made it possible to reach a new level, and in 1965. The fuel cells were tested in the USA on the Gemini-5 spacecraft, and later on on the Apollo spacecraft for flights to the Moon and under the Shuttle program.

In the USSR, fuel cells were developed at NPO Kvant, also for use in space. In those years, new materials already appeared - solid polymer electrolytes based on ion-exchange membranes, new types of catalysts, electrodes. Nevertheless, the working current density was small - within 100-200 mA / cm2, and the platinum content on the electrodes was several g / cm2. There were many problems related to durability, stability, safety.

The next stage in the rapid development of fuel cells began in the 90s. last century and continues now. It is caused by the need for new efficient energy sources in connection, on the one hand, with the global environmental problem the increasing emission of greenhouse gases from the combustion of fossil fuels and, on the other hand, with the depletion of such fuel reserves. Since the end product of hydrogen combustion in a fuel cell is water, they are considered the cleanest in terms of environmental impact. The main problem lies only in finding an efficient and inexpensive method for producing hydrogen.

Billions of financial investments in the development of fuel cells and hydrogen generators should lead to a technological breakthrough and make them a reality in everyday life: in cells for cell phones, in cars, in power plants. Already now, such automotive giants as Ballard, Honda, Daimler Chrysler, General Motors are demonstrating cars and buses running on 50 kW fuel cells. A number of companies have developed demonstration power plants on fuel cells with solid oxide electrolyte with a capacity of up to 500 kW... But, despite a significant breakthrough in improving the characteristics of fuel cells, there are still many problems to be solved related to their cost, reliability, and safety.

In a fuel cell, unlike batteries and accumulators, both the fuel and the oxidizer are supplied to it from the outside. The fuel cell is only a mediator in the reaction and, under ideal conditions, could work almost forever. The beauty of this technology is that in fact, the element burns fuel and directly converts the released energy into electricity. With direct combustion of fuel, it is oxidized by oxygen, and the heat released during this is used to perform useful work.

In a fuel cell, as in batteries, the reactions of fuel oxidation and oxygen reduction are spatially separated, and the "combustion" process takes place only if the cell delivers current to the load. It's like diesel electric generator, only without diesel and generator... And also without smoke, noise, overheating and with a much higher efficiency. The latter is explained by the fact that, firstly, there are no intermediate mechanical devices and, secondly, the fuel cell is not a heat engine and, as a result, does not obey Carnot's law (that is, its efficiency is not determined by the temperature difference).

Oxygen is used as an oxidizing agent in fuel cells. Moreover, since there is enough oxygen in the air, there is no need to worry about the supply of the oxidizer. Fuel is hydrogen. So, a reaction takes place in the fuel cell:

2H2 + O2 → 2H2O + electricity + heat.

The result is useful energy and water vapor. The simplest in its structure is proton exchange membrane fuel cell(see figure 1). It works as follows: the hydrogen entering the element decomposes under the action of the catalyst into electrons and positively charged hydrogen ions H +. Then a special membrane comes into play, which plays the role of an electrolyte in a conventional battery. By virtue of its chemical composition it allows protons to pass through itself, but retains electrons. Thus, electrons accumulated at the anode create an excess negative charge, and hydrogen ions create a positive charge at the cathode (the voltage across the cell is about 1V).

To create high power, a fuel cell is assembled from a plurality of cells. If the element is included in the load, then electrons will flow through it to the cathode, creating a current and completing the process of hydrogen oxidation with oxygen. As a catalyst in such fuel cells, as a rule, platinum microparticles supported on carbon fiber are used. Due to its structure, such a catalyst is highly gas and electricity permeable. The membrane is usually made from sulfur-containing polymer, Nafion. The membrane thickness is equal to tenths of a millimeter. During the reaction, of course, heat is also released, but there is not so much of it, so the operating temperature is maintained in the range of 40-80 ° C.

Fig. 1. How the fuel cell works

There are other types of fuel cells, mainly differing in the type of electrolyte used. Almost all of them require hydrogen as fuel, so a logical question arises: where to get it. Of course, it would be possible to use compressed hydrogen from cylinders, but then problems immediately arise associated with the transportation and storage of this highly flammable gas under high pressure. Of course, hydrogen can be used in a bound form as in metal hydride batteries. But still, the problem of its production and transportation remains, because the infrastructure of hydrogen refueling does not exist.

However, there is also a solution - liquid hydrocarbon fuel can be used as a source of hydrogen. For example, ethyl or methyl alcohol. True, a special additional device is already required here - a fuel converter, which converts alcohols into a mixture of gaseous H2 and CO2 at a high temperature (for methanol it will be somewhere around 240 ° C). But in this case, it is already more difficult to think about portability - such devices are good to use as stationary or, but for compact mobile equipment you need something less cumbersome.

And here we come to exactly the device, the development of which is being done with terrible force by almost all the largest electronics manufacturers - methanol fuel cell(Figure 2).

Fig. 2. How a methanol fuel cell works

The fundamental difference between hydrogen and methanol fuel cells lies in the catalyst used. A catalyst in a methanol fuel cell allows protons to be removed directly from the alcohol molecule. Thus, the issue of fuel is solved - methyl alcohol is massively produced for the chemical industry, it is easy to store and transport, and to charge a methanol fuel cell, it is enough to simply replace the fuel cartridge. True, there is one significant drawback - methanol is toxic. In addition, the efficiency of a methanol fuel cell is significantly lower than that of a hydrogen fuel cell.

Rice. 3. Methanol fuel cell

The most tempting option is to use ethyl alcohol as fuel, since the production and distribution of alcoholic beverages of any composition and strength is well established throughout the globe. However, the efficiency of ethanol fuel cells, unfortunately, is even lower than that of methanol.

As noted in the many years of development in the fuel cell field, various types of fuel cells have been built. Fuel cells are classified by electrolyte and fuel type.

1. Solid polymer hydrogen-oxygen electrolyte.

2. Solid polymer methanol fuel cells.

3. Cells on alkaline electrolyte.

4. Phosphoric acid fuel cells.

5. Fuel cells based on molten carbonates.

6. Solid oxide fuel cells.

Ideally, the efficiency of fuel cells is very high, but in real conditions there are losses associated with nonequilibrium processes, such as: ohmic losses due to the specific conductivity of the electrolyte and electrodes, activation and concentration polarization, diffusion losses. As a result, part of the energy generated in fuel cells is converted into heat. The efforts of specialists are aimed at reducing these losses.

The main source of ohmic losses, as well as the reason for the high cost of fuel cells, are perfluorinated sulfonic cation exchange membranes. The search is now underway for alternative, cheaper proton-conducting polymers. Since the conductivity of these membranes (solid electrolytes) reaches an acceptable value (10 Ohm / cm) only in the presence of water, the gases supplied to the fuel cell must be additionally humidified in a special device, which also increases the cost of the system. In catalytic gaseous diffusion electrodes, mainly platinum and some other noble metals are used, and so far no replacement has been found for them. Although the platinum content in fuel cells is several mg / cm2, for large batteries its amount reaches tens of grams.

When designing fuel cells, much attention is paid to the heat removal system, since at high current densities (up to 1A / cm2), self-heating of the system occurs. For cooling, water circulating in the fuel cell through special channels is used, and at low power, air is blown.

So, the modern electrochemical generator system, in addition to the fuel cell itself, is "overgrown" with many auxiliary devices, such as: pumps, a compressor for air supply, hydrogen admission, a gas humidifier, a cooling unit, a gas leakage control system, a DC-to-AC converter, a control processor and others. All this leads to the fact that the cost of the fuel cell system in 2004-2005 was 2-3 thousand USD / kW. According to experts, fuel cells will become available for use in transport and stationary power plants at a price of $ 50-100 / kW.

For the introduction of fuel cells into everyday life, along with the reduction in the cost of components, one should expect new original ideas and approaches. In particular, great hopes are pinned on the use of nanomaterials and nanotechnology. For example, several companies recently announced the creation of ultra-efficient catalysts, in particular, for an oxygen electrode based on clusters of nanoparticles of various metals. In addition, there have been reports of membraneless fuel cell designs in which liquid fuel (such as methanol) is fed into the fuel cell along with an oxidizer. The developed concept of biofuel cells operating in polluted waters and consuming dissolved atmospheric oxygen as an oxidizer and organic impurities as a fuel is also interesting.

According to experts, fuel cells will enter the mass market in the coming years. Indeed, developers one after another conquer technical problems, report successes and present prototypes of fuel cells. For example, Toshiba has demonstrated a finished prototype of a methanol fuel cell. It has a size of 22x56x4.5mm and gives a power of about 100mW. One filling in 2 cubes of concentrated (99.5%) methanol is enough for 20 hours of operation of the MP3 player. Toshiba has launched a commercial fuel cell for powering mobile phones. Again, the same Toshiba demonstrated a battery for notebooks measuring 275x75x40mm, which allows the computer to work for 5 hours from one refueling.

Another Japanese company, Fujitsu, does not lag behind Toshiba. In 2004, she also introduced an element that acts on a 30% aqueous solution of methanol. This fuel cell ran on one 300ml filling for 10 hours and at the same time delivered 15 watts of power.

Casio is developing a fuel cell in which methanol is first converted into a mixture of H2 and CO2 gases in a miniature fuel converter and then fed into the fuel cell. During the demonstration, the Casio prototype powered the laptop for 20 hours.

Samsung also made a name for itself in the field of fuel cells - in 2004, it demonstrated its 12W prototype designed to power a laptop. In general, Samsung intends to use fuel cells, first of all, in fourth-generation smartphones.

I must say that Japanese companies in general have very thoroughly approached the development of fuel cells. Back in 2003, companies such as Canon, Casio, Fujitsu, Hitachi, Sanyo, Sharp, Sony and Toshiba joined forces to develop a single fuel cell standard for laptops, mobile phones, PDAs and other electronic devices. American companies, which are also numerous in this market, mostly work under contracts with the military and develop fuel cells for the electrification of American soldiers.

The Germans are not far behind - Smart Fuel Cell sells fuel cells to power a mobile office. The device is called Smart Fuel Cell C25, has dimensions of 150x112x65mm and can deliver up to 140 watt-hours on a single refueling. This is enough to power the laptop for about 7 hours. Then the cartridge can be replaced and you can continue working. The size of the methanol cartridge is 99x63x27 mm, and it weighs 150g. The system itself weighs 1.1 kg, so you cannot call it completely portable, but still it is a completely finished and convenient device. The company is also developing a fuel module for powering professional video cameras.

In general, fuel cells have already entered the mobile electronics market. It remains for manufacturers to solve the last technical problems before starting mass production.

First, it is necessary to resolve the issue of miniaturization of fuel cells. After all, the smaller the fuel cell, the less power it will be able to deliver - so new catalysts and electrodes are constantly being developed to maximize the working surface with small dimensions. Here, the latest developments in the field of nanotechnology and nanomaterials (for example, nanotubes) come in very handy. Again, the achievements of microelectromechanics are increasingly being used to miniaturize the piping of elements (fuel and water pumps, cooling systems and fuel conversion).

The second major issue to be addressed is cost. Indeed, very expensive platinum is used as a catalyst in most fuel cells. Again, some of the manufacturers are trying to make the most of already well-established silicon technologies.

As for other areas of use of fuel cells, fuel cells have already firmly established themselves there, although they have not yet become mainstream either in the energy sector or in transport. Already a great many car manufacturers have presented their concept cars powered by fuel cells. There are fuel cell buses in several cities around the world. Canadian Ballard Power Systems manufactures a range of stationary generators ranging from 1 to 250 kW. At the same time, kilowatt generators are designed to immediately supply one apartment with electricity, heat and hot water.

The United States has adopted several initiatives to develop hydrogen fuel cells, infrastructure and technologies to make fuel cell vehicles practical and economical by 2020. More than one billion dollars have been allocated for these purposes.

Fuel cells generate electricity quietly and efficiently without polluting the environment. Unlike energy sources that use fossil fuels, the byproducts of fuel cells are heat and water. How it works?

In this article, we will briefly review each of the existing fuel technologies today, as well as talk about the design and operation of fuel cells, and compare them with other forms of energy production. We will also discuss some of the obstacles researchers face to make fuel cells practical and affordable for consumers.

Fuel cells are electrochemical energy conversion devices... A fuel cell converts chemicals, hydrogen and oxygen into water, in the process generating electricity.

Another electrochemical device that we are all familiar with is the battery. The battery has all the necessary chemical elements inside it and converts these substances into electricity. This means that the battery eventually "dies" and you either throw it away or recharge it.

In a fuel cell, chemicals are constantly flowing into it so that it never "dies". Electricity will be generated for as long as there is a flow of chemicals into the element. Most fuel cells in use today use hydrogen and oxygen.

Hydrogen is the most abundant element in our galaxy. However, hydrogen practically does not exist on Earth in its elemental form. Engineers and scientists must extract pure hydrogen from hydrogen compounds, including fossil fuels or water. To extract hydrogen from these compounds, you need to spend energy in the form of heat or electricity.

The invention of fuel cells

Sir William Grove invented the first fuel cell in 1839. Grove knew that water could be separated into hydrogen and oxygen by passing an electric current through it (a process called electrolysis). He suggested that in reverse order one could get electricity and water. He created a primitive fuel cell and named it gas galvanic battery... By experimenting with his new invention, Grove proved his hypothesis. Fifty years later, scientists Ludwig Mond and Charles Langer coined the term fuel cells when trying to build a practical model for electricity generation.

The fuel cell will compete with many other energy conversion devices, including gas turbines in urban power plants, internal combustion engines in cars, and all kinds of batteries. Internal combustion engines, like gas turbines, burn a variety of fuels and use the pressure created by the expansion of the gases to perform mechanical work. Batteries convert chemical energy into electrical energy when needed. Fuel cells must perform these tasks more efficiently.

The fuel cell provides DC (direct current) voltage that can be used to power electric motors, lighting and other electrical appliances.

There are several different types of fuel cells, each of which uses a different chemical process. Fuel cells are usually classified according to their operating temperature and typeelectrolyte, which they are using. Some types of fuel cells are well suited for use in stationary power plants. Others can be useful for small handheld devices or for powering cars. The main types of fuel cells include:

Polymer exchange membrane fuel cell (PEMFC)

PEMFC is considered as the most likely candidate for transport applications. The PEMFC has both high power and relatively low operating temperature (ranging from 60 to 80 degrees Celsius). A low operating temperature means the fuel cells can quickly heat up to start generating electricity.

Solid oxide fuel cell (SOFC)

These fuel cells are most suitable for large stationary power generators that could power a factory or city. This type of fuel cell works with very high temperatures(from 700 to 1000 degrees Celsius). The high temperature is a reliability problem because some of the fuel cells can fail after several cycles of switching on and off. However, solid oxide fuel cells are very stable in continuous operation. Indeed, SOFCs have demonstrated the longest lifespan of any fuel cell under certain conditions. The high temperature also has an advantage: the steam generated by the fuel cells can be directed to the turbines and generate more electricity. This process is called cogeneration of heat and electricity and improves the overall efficiency of the system.

Alkaline fuel cell (AFC)

It is one of the oldest fuel cell designs in use since the 1960s. AFCs are highly susceptible to contamination as they require pure hydrogen and oxygen. In addition, they are very expensive, so this type of fuel cell is unlikely to be put into mass production.

Molten-carbonate fuel cell (MCFC)

Like SOFCs, these fuel cells are also best suited for large stationary power plants and generators. They operate at 600 degrees Celsius, so they can generate steam, which in turn can be used to generate even more power. They have a lower operating temperature than solid oxide fuel cells, which means they do not need such heat-resistant materials. This makes them a little cheaper.

Phosphoric-acid fuel cell (PAFC)

Phosphoric acid fuel cell has the potential to be used in small stationary power systems. It operates at a higher temperature than a polymer exchange membrane fuel cell, so it takes longer to warm up, making it unsuitable for use in automobiles.

Direct methanol fuel cell (DMFC)

Methanol fuel cells are comparable to PEMFCs in terms of operating temperature, but not as efficient. In addition, DMFCs require quite a lot of platinum to act as a catalyst, which makes these fuel cells expensive.

Fuel cell with polymer exchange membrane

The Polymer Membrane Exchange Fuel Cell (PEMFC) is one of the most promising fuel cell technologies. PEMFC uses one of the simplest reactions of any fuel cell. Consider what it consists of.

1. BUT node - negative terminal of the fuel cell. It conducts electrons, which are released from hydrogen molecules, after which they can be used in the external circuit. It has engraved channels through which hydrogen gas is distributed evenly over the catalyst surface.

2.TO atode - the positive terminal of the fuel cell also has channels for oxygen distribution over the catalyst surface. It also conducts electrons back from the outer catalyst chain, where they can combine with hydrogen and oxygen ions to form water.

3.Electrolyte-proton exchange membrane... It is a specially processed material that only conducts positively charged ions and blocks electrons. With PEMFCs, the membrane must be moist in order to function properly and remain stable.

4. Catalyst is a special material that promotes the reaction of oxygen and hydrogen. It is usually made from platinum nanoparticles applied very thinly to carbon paper or fabric. The catalyst has a surface structure such that the maximum surface area of ​​the platinum can be exposed to hydrogen or oxygen.

The figure shows hydrogen gas (H2) pressurized into the fuel cell from the anode side. When an H2 molecule comes into contact with platinum on the catalyst, it splits into two H + ions and two electrons. The electrons pass through the anode, where they are used in an external circuit (doing useful work, such as rotating a motor) and back to the cathode side of the fuel cell.

Meanwhile, on the cathode side of the fuel cell, oxygen (O2) from the air passes through the catalyst where it forms two oxygen atoms. Each of these atoms has a strong negative charge. This negative charge attracts two H + ions across the membrane, where they combine with an oxygen atom and two electrons coming from an external circuit to form a water molecule (H2O).

This reaction in a single fuel cell produces only about 0.7 volts. To raise the voltage to a reasonable level, many individual fuel cells must be combined to form a fuel cell stack. Bipolar plates are used to connect one fuel cell to another and undergo de-potential oxidation. A big problem with bipolar plates is their stability. Metal bipolar plates can be corroded and by-products (iron and chromium ions) reduce the efficiency of the fuel cell membranes and electrodes. Therefore, low temperature fuel cells use light metals, graphite, and composite compounds of carbon and thermosetting material (thermosetting material is a kind of plastic that remains solid even when exposed to high temperatures) in the form of a bipolar sheet material.

Fuel cell efficiency

Reducing pollution is one of the primary goals of a fuel cell. Comparing a car powered by a fuel cell to a car powered by a gasoline engine and a car powered by a battery, you will see how fuel cells could improve the efficiency of cars.

Since all three types of cars have many of the same components, we will ignore this part of the car and compare the efficiencies up to the point where mechanical energy is produced. Let's start with a fuel cell vehicle.

If a fuel cell is powered by pure hydrogen, its efficiency can be up to 80 percent. Thus, it converts 80 percent of the energy content of hydrogen into electricity. However, we still have to convert electricity into mechanical work. This is achieved by an electric motor and an inverter. The efficiency of the motor + inverter is also approximately 80 percent. This gives a total efficiency of approximately 80 * 80/100 = 64 percent. Honda's FCX concept vehicle reportedly has 60 percent energy efficiency.

If the fuel source is not pure hydrogen, then the vehicle will also need a reformer. Reformers convert hydrocarbon or alcohol fuels to hydrogen. They generate heat and produce CO and CO2 in addition to hydrogen. They use various devices to purify the produced hydrogen, but this purification is insufficient and lowers the efficiency of the fuel cell. Therefore, the researchers decided to focus on fuel cells for vehicles powered by pure hydrogen, despite the problems associated with the production and storage of hydrogen.

Efficiency of a gasoline engine and a car on electric batteries

The efficiency of a petrol-powered car is surprisingly low. All the heat that comes out in the exhaust or is absorbed by the radiator is wasted energy. The engine also uses a lot of energy to turn the various pumps, fans, and generators that keep it running. Thus, the overall efficiency of an automotive gasoline engine is approximately 20 percent. Thus, only about 20 percent of the thermal energy content of gasoline is converted into mechanical work.

A battery-powered electric vehicle has a fairly high efficiency. The battery is approximately 90 percent efficient (most batteries generate some heat or require heating) and the motor + inverter is approximately 80 percent efficient. This gives an overall efficiency of approximately 72 percent.

But that's not all. In order for an electric car to move, electricity must first be generated somewhere. If it was a power plant that used the process of burning fossil fuels (rather than nuclear, hydroelectric, solar, or wind power), then only about 40 percent of the fuel consumed by the power plant was converted to electricity. Plus, the car charging process requires converting AC power to DC power. This process has an efficiency of approximately 90 percent.

Now, if we look at the whole cycle, the efficiency of an electric vehicle is 72 percent for the car itself, 40 percent for a power plant and 90 percent for charging the car. This gives an overall efficiency of 26 percent. The overall efficiency varies greatly depending on which power station is used to charge the battery. If the electricity for the car is generated, for example, by a hydroelectric power plant, then the efficiency of the electric car will be approximately 65 percent.

Scientists are researching and improving designs to continue to improve the efficiency of the fuel cell. One new approach is to integrate fuel cell and battery-powered vehicles. A concept vehicle powered by a fuel cell-powered hybrid powertrain is being developed. It uses a lithium battery to power the vehicle while the fuel cell recharges the battery.

Fuel cell vehicles are potentially as efficient as a battery-powered car that is being charged from a power plant that does not use fossil fuels. But achieving this potential in a practical and affordable way can be difficult.

Why use fuel cells?

The main reason is everything related to oil. America must import nearly 60 percent of its oil. By 2025, imports are expected to grow to 68%. Americans use two-thirds of their oil every day for transportation. Even if every car on the street were a hybrid car, by 2025 the US would still have to use the same amount of oil that Americans consumed in 2000. Indeed, America consumes a quarter of the world's oil, although only 4.6% of the world's population lives here.

Experts expect oil prices to continue to rise over the next several decades as cheaper sources are depleted. Oil companies must develop oil fields in an increasingly difficult environment, which will drive up oil prices.

Fears extend far beyond economic security. A lot of funds received from the sale of oil are spent on the maintenance of international terrorism, radical political parties, and an unstable situation in the oil-producing regions.

The use of oil and other fossil fuels for energy produces pollution. It is best suited for everyone to find an alternative — burning fossil fuels for energy.

Fuel cells are an attractive alternative to oil dependence. Instead of pollution, fuel cells produce clean water as a by-product. While engineers have temporarily focused on producing hydrogen from various fossil sources such as gasoline or natural gas, renewable, environmentally friendly ways of producing hydrogen in the future are being explored. The most promising, naturally, will be the process of producing hydrogen from water.

Oil dependence and global warming are an international problem. Several countries are jointly involved in the development of research and development for fuel cell technology.

Obviously, scientists and manufacturers have to work hard before fuel cells become an alternative to modern energy production methods. Yet, with worldwide support and global cooperation, a viable fuel cell energy system could be a reality in just a couple of decades.

A fuel cell is an electrochemical energy conversion device that, due to chemical reaction converts hydrogen and oxygen into electricity. As a result of this process, water is formed and a large amount of heat is generated. A fuel cell is very similar to a battery, which can be charged and then used up with stored electrical energy.
The inventor of the fuel cell is considered to be William R. Grove, who invented it back in 1839. In this fuel cell, a solution of sulfuric acid was used as an electrolyte, and hydrogen was used as a fuel, which combined with oxygen in an oxidizing medium. It should be noted that until recently, fuel cells were used only in laboratories and on spacecraft.
In the future, fuel cells will be able to compete with many other systems for converting energy (including a gas turbine in power plants) internal combustion engines in a car and electric batteries in portable devices. Internal combustion engines burn fuel and use the pressure created by the expansion of combustion gases to perform mechanical work. Batteries store electrical energy, converting it to chemical energy, which can be converted back to electrical energy if needed. Fuel cells are potentially very efficient. Back in 1824, the French scientist Carnot proved that the compression-expansion cycles of an internal combustion engine cannot provide the efficiency of conversion of thermal energy (which is the chemical energy of the burning fuel) into mechanical energy above 50%. A fuel cell has no moving parts (at least within the cell itself) and therefore do not obey Carnot's law. Naturally, they will have more than 50% efficiency and are especially effective at low loads. Thus, fuel cell vehicles are poised to become (and have already proven) more fuel efficient than conventional vehicles under real-world driving conditions.
The fuel cell generates a constant voltage electric current that can be used to drive the electric motor, lighting devices and other electrical systems in the vehicle. There are several types of fuel cells, differing in the chemical processes used. Fuel cells are usually classified by the type of electrolyte they use. Some types of fuel cells are promising for use as power plants for power plants, while others may be useful for small portable devices or for driving cars.
An alkaline fuel cell is one of the earliest developed cells. They have been used in the US space program since the 1960s. Such fuel cells are very susceptible to contamination and therefore require very pure hydrogen and oxygen. In addition, they are very expensive and therefore this type of fuel cell is unlikely to find widespread use in automobiles.
Fuel cells based on phosphoric acid can be used in stationary installations of low power. They operate at a fairly high temperature and therefore take a long time to warm up, which also makes them ineffective for use in automobiles.
Solid oxide fuel cells are better suited for large stationary power generators that could power factories or settlements... This type of fuel cell operates at very high temperatures (around 1000 ° C). The high operating temperature creates certain problems, but on the other hand, there is an advantage - the steam produced by the fuel cell can be sent to the turbines to generate more electricity. In general, this improves the overall efficiency of the system.
One of the most promising systems is the Protone Exchange Membrane Fuel Cell (PEMFC). At the moment, this type of fuel cell is the most promising because it can propel cars, buses and other vehicles.

Chemical processes in a fuel cell

Fuel cells use an electrochemical process to combine hydrogen with oxygen from the air. Like batteries, fuel cells use electrodes (solid electrical conductors) in an electrolyte (electrically conductive medium). When hydrogen molecules come into contact with the negative electrode (anode), the latter are split into protons and electrons. Protons travel through the proton exchange membrane (PEM) to the positive electrode (cathode) of the fuel cell, producing electricity. There is a chemical combination of hydrogen and oxygen molecules with the formation of water as a by-product of this reaction. The only emission from a fuel cell is water vapor.
The electricity produced by the fuel cells can be used in a vehicle's electrical transmission (consisting of an electrical converter and an AC induction motor) to generate mechanical energy to drive the vehicle. The work of the power converter is to convert the direct electric current produced by the fuel cells into alternating current, on which the traction motor of the vehicle operates.

Diagram of a fuel cell with a proton-exchange membrane:
1 - anode;
2 - proton exchange membrane (PEM);
3 - catalyst (red);
4 - cathode

The Proton Exchange Membrane Fuel Cell (PEMFC) uses one of the simplest reactions of any fuel cell.

Separate fuel cell cell

Let's consider how the fuel cell works. The anode, the negative pole of the fuel cell, conducts electrons that are freed from hydrogen molecules so that they can be used in an external electrical circuit (circuit). For this, channels are engraved in it, distributing hydrogen evenly over the entire surface of the catalyst. The cathode (positive pole of the fuel cell) has engraved channels that distribute oxygen over the catalyst surface. It also conducts electrons back from the outer loop (circuit) to the catalyst, where they can combine with hydrogen ions and oxygen to form water. The electrolyte is a proton exchange membrane. It is a special material, similar to ordinary plastic, but with the ability to pass positively charged ions and block the passage of electrons.
A catalyst is a special material that facilitates the reaction between oxygen and hydrogen. The catalyst is usually made from platinum powder coated in a very thin layer on carbon paper or cloth. The catalyst must be rough and porous in order for its surface to be in maximum contact with hydrogen and oxygen. The platinum-coated side of the catalyst is in front of the proton exchange membrane (PEM).
Hydrogen gas (H 2) is supplied to the fuel cell under pressure from the anode side. When an H2 molecule comes into contact with platinum on the catalyst, it splits into two parts, two ions (H +) and two electrons (e–). The electrons are conducted through the anode, where they travel through the outer loop (circuit) to do useful work (such as driving an electric motor) and return from the cathode side of the fuel cell.
Meanwhile, at the cathode side of the fuel cell, oxygen gas (O 2) is forced through the catalyst where it forms two oxygen atoms. Each of these atoms has a strong negative charge that attracts two H + ions across the membrane, where they combine with an oxygen atom and two electrons from the outer circuit (chain) to form a water molecule (H 2 O).
This reaction in a single fuel cell produces approximately 0.7 watts of power. To raise the power to the required level, many individual fuel cells must be combined to form a fuel cell stack.
POM fuel cells operate at a relatively low temperature (around 80 ° C), which means that they can be quickly heated to operating temperature and do not require expensive cooling systems. Continuous improvement of the technologies and materials used in these cells have brought their power closer to the level when a battery of such fuel cells, which occupies a small part of the trunk of a car, can provide the energy needed to drive a car.
Over the past years, most of the world's leading car manufacturers have invested heavily in fuel cell vehicle designs. Many have already demonstrated fuel cell vehicles with satisfactory power and dynamic performance, although they were quite expensive.
The improvement of the designs of such vehicles is going on very intensively.

A fuel cell vehicle uses a power plant located under the floor of the vehicle

The NECAR V car is made on the basis of the Mercedes-Benz A-class car, and the entire power plant, together with the fuel cells, is located under the floor of the car. Such constructive solution makes it possible to place four passengers and luggage in the car. Here, not hydrogen, but methanol is used as fuel for the car. Methanol is converted to hydrogen by a reformer (a device that converts methanol to hydrogen) to power the fuel cell. The use of the reformer on board the vehicle makes it possible to use almost any hydrocarbon as fuel, which makes it possible to refuel a fuel cell vehicle using the existing network of filling stations. In theory, fuel cells produce nothing but electricity and water. Converting fuel (gasoline or methanol) into hydrogen, which is required for a fuel cell, somewhat reduces the environmental attractiveness of such a car.
Honda, which has been involved in fuel cells since 1989, manufactured a small batch of Honda FCX-V4s with Ballard proton exchange membrane fuel cells in 2003. These fuel cells generate 78 kW of electrical power, while traction motors with a power of 60 kW and a torque of 272 Nm are used to drive the drive wheels. it has excellent dynamics, and the supply of compressed hydrogen makes it possible to run up to 355 km.

The Honda FСX car uses electric energy for movement, obtained by means of fuel cells.
The Honda FCX is the world's first fuel cell vehicle to receive US government certification. The vehicle is ZEV - Zero Emission Vehicle certified. Honda is not going to sell these cars yet, but is leasing about 30 cars in units. California and Tokyo, where a hydrogen refueling infrastructure already exists.

General Motors' Hy Wire concept car features fuel cell powertrain

General Motors is conducting extensive research into the development and creation of fuel cell vehicles.

Hy Wire car chassis

The GM Hy Wire concept car has received 26 patents. The basis of the car is a 150 mm thick functional platform. Inside the platform are hydrogen tanks, a fuel cell power plant and vehicle control systems using the latest electronic control technology by wire. The Hy Wire chassis is a thin platform that encloses all of the vehicle's major structural elements: hydrogen tanks, fuel cells, batteries, electric motors and control systems. This approach to design makes it possible to change car bodies during operation. The company is also testing prototype Opel fuel cell vehicles and is designing a fuel cell plant.

Liquefied Hydrogen Safe Fuel Tank Design:
1 - filling device;
2 - external tank;
3 - supports;
4 - level sensor;
5 - inner tank;
6 - filling line;
7 - insulation and vacuum;
8 - heater;
9 - mounting box

The BMW company pays much attention to the problem of using hydrogen as a fuel for automobiles. Together with Magna Steyer, a firm known for its work on the use of liquefied hydrogen in space research, BMW has developed a liquefied hydrogen fuel tank that can be used in automobiles.

Tests have confirmed the safety of using a liquid hydrogen fuel tank

The company has carried out a series of tests for the safety of the structure using standard methods and confirmed its reliability.
In 2002, the Mini Cooper Hydrogen was shown at the Frankfurt Motor Show (Germany), which uses liquefied hydrogen as fuel. The fuel tank of this vehicle occupies the same space as a regular gas tank. The hydrogen in this car is not used for fuel cells, but as fuel for the internal combustion engine.

World's first production vehicle with a fuel cell instead of a battery

In 2003, BMW announced the production of the first production vehicle with a fuel cell, the BMW 750 hL. A fuel cell battery is used instead of a traditional battery. This car has a 12-cylinder internal combustion engine that runs on hydrogen, and the fuel cell serves as an alternative to a conventional battery, allowing the air conditioner and other electrical consumers to operate when the car is parked for long periods of time with the engine inoperative.

Refueling with hydrogen is carried out by a robot, the driver is not involved in this process

The same BMW company has also developed robotic fuel dispensers, which ensure fast and safe refueling of cars with liquefied hydrogen.
A large number of developments in recent years aimed at creating cars using alternative fuels and alternative power plants indicate that the internal combustion engines, which have dominated cars over the past century, will eventually give way to cleaner, environmentally efficient and silent designs. Their wide distribution is currently constrained not by technical, but rather by economic and social problems. For their widespread use, it is necessary to create a certain infrastructure for the development of the production of alternative fuels, the creation and distribution of new filling stations and to overcome a number of psychological barriers. The use of hydrogen as a vehicle fuel will require storage, delivery and distribution issues with serious safety measures.
In theory, hydrogen is available in unlimited quantities, but its production is very energy intensive. In addition, to transfer cars to work on hydrogen fuel, it is necessary to make two major changes to the power system: first, transfer its operation from gasoline to methanol, and then, for some time, to hydrogen. It will take some time before this issue is resolved.

Fuel cell ( Fuel cell) Is a device that converts chemical energy into electrical energy. It is similar in principle to a conventional battery, but differs in that its operation requires a constant supply of substances from the outside for an electrochemical reaction to proceed. The fuel cells are supplied with hydrogen and oxygen, and the output is electricity, water and heat. Their advantages include environmental friendliness, reliability, durability and ease of use. Unlike conventional batteries, electrochemical converters can operate almost indefinitely as long as fuel is supplied. They do not need to be charged for hours before being fully charged. Moreover, the cells themselves can charge the battery while the car is parked with the engine turned off.

The most common in hydrogen vehicles are proton membrane fuel cells (PEMFC) and solid oxide fuel cells (SOFC).

A fuel cell with a proton exchange membrane operates as follows. Between the anode and cathode there is a special membrane and a platinum-coated catalyst. Hydrogen is supplied to the anode, and oxygen is supplied to the cathode (for example, from air). At the anode, hydrogen is decomposed by a catalyst into protons and electrons. Hydrogen protons pass through the membrane and hit the cathode, while electrons are released into the external circuit (the membrane does not allow them to pass through). The potential difference obtained in this way leads to the appearance of an electric current. On the cathode side, hydrogen protons are oxidized by oxygen. As a result, water vapor is produced, which is the main element of the vehicle's exhaust gases. Possessing high efficiency, PEM cells have one significant drawback - they require pure hydrogen for their operation, the storage of which is a rather serious problem.

If a catalyst is found that replaces expensive platinum in these cells, then a cheap fuel cell for generating electricity will immediately be created, which means the world will get rid of oil dependence.

Solid oxide cells

SOFC solid oxide cells are significantly less demanding on fuel cleanliness. In addition, thanks to the use of a POX (Partial Oxidation) reformer, these cells can consume regular gasoline as fuel. The process of converting gasoline directly into electricity is as follows. In a special device - a reformer, at a temperature of about 800 ° C, gasoline evaporates and decomposes into its constituent elements.

This produces hydrogen and carbon dioxide. Further, also under the influence of temperature and using directly SOFC (consisting of a porous ceramic material based on zirconium oxide), hydrogen is oxidized by oxygen in the air. After obtaining hydrogen from gasoline, the process proceeds further according to the scenario described above, with only one difference: the SOFC fuel cell, in contrast to devices operating on hydrogen, is less sensitive to impurities in the initial fuel. So the quality of the gasoline should not affect the performance of the fuel cell.

The high operating temperature of SOFC (650-800 degrees) is a significant drawback, the warm-up process takes about 20 minutes. On the other hand, excess heat is not a problem, since it is completely removed by the remaining air and exhaust gases produced by the reformer and the fuel cell itself. This allows the SOFC system to be integrated into the vehicle as a stand-alone device in a thermally insulated housing.

The modular structure allows the required voltage to be achieved by daisy-chaining a set of standard cells. And, perhaps most importantly from the point of view of the introduction of such devices, SOFC does not have very expensive platinum-based electrodes. It is the high cost of these elements that is one of the obstacles in the development and dissemination of PEMFC technology.

Types of fuel cells

Currently, there are these types of fuel cells:

• AFC- Alkaline Fuel Cell (alkaline fuel cell);
• PAFC- Phosphoric Acid Fuel Cell (phosphoric acid fuel cell);
• PEMFC- Proton Exchange Membrane Fuel Cell
• DMFC- Direct Methanol Fuel Cell (fuel cell with direct methanol decomposition);
• MCFC Molten Carbonate Fuel Cell
• SOFC- Solid Oxide Fuel Cell (solid oxide fuel cell).

Fuel cells (electrochemical generators) represent a highly efficient, durable, reliable and environmentally friendly method of generating energy. Initially, they were used only in the space industry, but today electrochemical generators are increasingly used in various fields: these are power supplies for mobile phones and laptops, vehicle engines, autonomous power supplies for buildings, stationary power plants. Some of these devices work as laboratory prototypes, some are used for demonstration purposes or are undergoing pre-production tests. However, many models are already used in commercial projects and are mass-produced.

Device

Fuel cells are electrochemical devices capable of providing a high conversion rate of existing chemical energy into electrical energy.

The fuel cell device consists of three main parts:

1. Power Generation Section;
2. CPU;
3. Voltage transformer.

The main part of the fuel cell is the power generation section, which is a stack made up of individual fuel cells. A platinum catalyst is included in the structure of the electrodes of the fuel cells. With the help of these cells, a constant electric current is generated.

One of these devices has the following characteristics: at a voltage of 155 volts, 1400 amperes are output. The battery measures 0.9 m in width and height and 2.9 m in length. The electrochemical process in it is carried out at a temperature of 177 ° C, which requires heating the battery at the time of start-up, as well as removing heat during its operation. For this purpose, a separate water circuit is included in the fuel cell, including the battery equipped with special cooling plates.

The fuel process converts natural gas into hydrogen, which is required for an electrochemical reaction. The main element of the fuel processor is the reformer. In it, natural gas (or other hydrogen-containing fuel) interacts at high pressure and high temperature (about 900 ° C) with water vapor under the action of a catalyst - nickel.

There is a burner to maintain the required temperature of the reformer. The steam required for the reforming is generated from the condensate. An unstable direct current is generated in the fuel cell stack, and a voltage converter is used to convert it.

Also in the voltage converter block there are:

• Control devices.
• Safety interlock circuits that shut off the fuel cell on various faults.

Operating principle

The simplest element with a proton exchange membrane consists of a polymer membrane that is located between the anode and cathode, as well as cathode and anode catalysts. The polymer membrane is used as an electrolyte.

• The proton exchange membrane looks like a thin solid organic compound of small thickness. This membrane works as an electrolyte; in the presence of water, it divides the substance into negatively as well as positively charged ions.
• Oxidation begins at the anode, and reduction occurs at the cathode. The cathode and anode in the PEM cell are made of a porous material, it is a mixture of platinum and carbon particles. Platinum acts as a catalyst, which facilitates the dissociation reaction. The cathode and anode are made porous so that oxygen and hydrogen can freely pass through them.
• The anode and cathode are located between two metal plates, they supply oxygen and hydrogen to the cathode and anode, and remove electrical energy, heat and water.
• Through the channels in the plate, hydrogen molecules enter the anode, where the molecules are decomposed into atoms.
• As a result of chemisorption, when exposed to a catalyst, hydrogen atoms are converted into positively charged hydrogen ions H +, that is, protons.
• Protons diffuse to the cathode through the membrane, and the flow of electrons goes to the cathode through a special external electrical circuit. A load is connected to it, that is, a consumer of electrical energy.
• Oxygen supplied to the cathode, when exposed, enters into a chemical reaction with electrons from the external electrical circuit and hydrogen ions from the proton-exchange membrane. This chemical reaction produces water.

The chemical reaction that occurs in other types of fuel cells (for example, with an acidic electrolyte in the form of phosphoric acid H3PO4) is completely identical to the reaction of a device with a proton-exchange membrane.

Views

Currently, several types of fuel cells are known, which differ in the composition of the electrolyte used:

• Fuel cells based on phosphoric or phosphoric acid (PAFC, Phosphoric Acid Fuel Cells).
• Devices with a proton exchange membrane (PEMFC, Proton Exchange Membrane Fuel Cells).
• Solid oxide fuel cells (SOFC, Solid Oxide Fuel Cells).
• Electrochemical generators based on molten carbonate (MCFC, Molten Carbonate Fuel Cells).

At the moment, electrochemical generators using PAFC technology have become more widespread.

Application

Today, fuel cells are used in Space Shuttle, reusable spacecraft. They use installations with a power of 12 watts. They generate all the electricity in the spacecraft. The water generated by the electrochemical reaction is used for drinking, including for cooling equipment.

Electrochemical generators were also used to power the Soviet Buran, a reusable ship.

Fuel cells are also used in the civilian sector.

• Stationary installations with a capacity of 5–250 kW and above. They are used as autonomous sources for heat and power supply of industrial, public and residential buildings, emergency and backup power supplies, uninterruptible power supplies.
• Portable units with a capacity of 1–50 kW. They are used for space satellites and ships. Copies for golf carts, wheelchairs, rail and cargo refrigerators, road signs are being created.
• Mobile units with a capacity of 25–150 kW. They are beginning to be used in warships and submarines, including cars and other vehicles. Prototypes have already been created by such automotive giants as Renault, Neoplan, Toyota, Volkswagen, Hyundai, Nissan, VAZ, General Motors, Honda, Ford and others.
• Microdevices with a power of 1–500 watts. They are used in experienced pocket computers, laptops, consumer electronic devices, mobile phones, and modern military devices.

Peculiarities

• Part of the chemical reaction energy in each fuel cell is released as heat. Cooling required. In the external circuit, the flow of electrons creates a constant current that is used to do the work. The termination of the movement of hydrogen ions or the opening of the external circuit leads to the termination of the chemical reaction.
• The amount of electricity generated by fuel cells is determined by gas pressure, temperature, geometric dimensions, and the type of fuel cell. To increase the amount of electricity generated by the reaction, the size of the fuel cells can be made larger, but in practice, several cells are used, which are combined into batteries.
• The chemical process in some types of fuel cells can be reversed. That is, when a potential difference is applied to the electrodes, water can be decomposed into oxygen and hydrogen, which will be collected on the porous electrodes. When the load is switched on, such a fuel cell will generate electrical energy.

Perspectives

Currently, electrochemical generators for use as the main source of energy require high initial costs. With the introduction of more stable membranes with high conductivity, efficient and cheap catalysts, and alternative sources of hydrogen, fuel cells will become highly economically attractive and will be introduced everywhere.

• The cars will run on fuel cells, there will be no internal combustion engine in them at all. Water or solid-state hydrogen will be used as a source of energy. Refueling will be simple and safe, and driving is environmentally friendly - only water vapor will be generated.
• All buildings will have their own portable fuel cell power generators.
• Electrochemical generators will replace all batteries and will be found in any electronics and household appliances.

Advantages and disadvantages

Each type of fuel cell has its own advantages and disadvantages. Some require high quality fuel, others have a complex design and require a high operating temperature.

In general, the following advantages of fuel cells can be indicated:

• safety for the environment;
• electrochemical generators do not need to be recharged;
• electrochemical generators can create energy constantly, they do not care about external conditions;
• flexibility in terms of scale and portability.

Among the disadvantages are:

• technical difficulties with fuel storage and transportation;
• imperfect elements of the device: catalysts, membranes, and so on.

Hydrogen fuel cells convert the chemical energy of the fuel into electricity, bypassing ineffective combustion processes and converting thermal energy into mechanical energy. A hydrogen fuel cell is electrochemical the device, as a result of highly efficient "cold" combustion of fuel, directly generates electricity. A hydrogen-air proton exchange membrane fuel cell (PEMFC) is one of the most promising fuel cell technologies.

Eight years ago in Western Europe six liquid diesel pumps were opened; they must be two hundred to the end. We are far from thousands of fast charging terminals that are hatching all over the place to stimulate the spread of electrical movement. And that's where the rub hurts. And we better declare graphene.

The batteries didn't say their last word

This is more than autonomy, so limiting the charging time slows down the spread of the electric vehicle. However, he recalled this month a note addressed to his customers that batteries have a limitation limited to this type of probe at very high voltages. Thomas Brachman will be told that the hydrogen distribution network still needs to be built. The argument that he sweeps his hand, recalling that multiplying fast charge terminals is also very expensive, due to the high cross-section of high voltage copper cables. "It is easier and cheaper to transport liquefied hydrogen by trucks from buried tanks near production sites."

A proton-conducting polymer membrane separates the two anode and cathode electrodes. Each electrode is a carbon plate (matrix) coated with a catalyst. On the anode catalyst, molecular hydrogen dissociates and donates electrons. Hydrogen cations are carried through the membrane to the cathode, but electrons are donated to the external circuit, since the membrane does not allow electrons to pass through.

Hydrogen is not yet a pure vector of electricity

As for the cost of the battery itself, which is very sensitive information, Thomas Brahmann has no doubt that it can be significantly reduced as efficiency increases. "Platinum is an element that costs more." Unfortunately, almost all hydrogen comes from fossil energy sources. Moreover, dihydrogen is just a vector of energy, and not a source from which, during its production, a non-negligible part is consumed, its liquefaction, and then its transformation into electricity.

On the cathode catalyst, an oxygen molecule combines with an electron (which is supplied from the electrical circuit) and an incoming proton and forms water, which is the only reaction product (in the form of vapor and / or liquid).

Membrane-electrode units are made from hydrogen fuel cells, which are a key generating element of the energy system.

The machine of the future behaves like a real one

The battery balance is about three times higher, despite heat losses in the drivers. Alas, the miracle car will not punch our roads, except as part of public demonstrations. Brahmann, who recalls that the natural silence of an electric car enhances the impression of living in a noisy world. Despite all the difficulties, the steering and brake pedal provides a natural consistency.

Tiny battery, but better performance

The gadget is visible, the central screen scatters the images of the camera placed in the right mirror as soon as the turn signal is activated. Most of our American clients are no longer demanding, and this keeps prices down — justifying the chief engineer offering a lower rate than. It's really worth talking about a stack of fuel cells, as there are 358s that work together. The main tank with a capacity of 117 liters, pressed against the back wall of the bench, prohibits folding it, and the second, 24 liters, is hidden under the seat.

Advantages of hydrogen fuel cells over traditional solutions:

- increased specific energy consumption (500 ÷ 1000 W * h / kg),

- extended operating temperature range (-40 0 С / +40 0 С),

- no heat spot, noise and vibration,

- reliability during cold start,

- practically unlimited storage life of energy (no self-discharge),

First two-stroke fuel cell

Despite its compact size, this new fuel cell converts dihydrogen into electricity faster and better than its predecessor. It delivers the pile elements to oxygen at a rate previously considered incompatible with their durability. Excess water that previously limited the flow rate is best evacuated. As a result, the power per cell is increased by half and the efficiency reaches 60%.

This is due to the presence of a 1.7 kWh lithium-ion battery - located under the front seats, which allows to deliver additional current during strong acceleration. Or the autonomy of the forecast is 460 km, ideally corresponds to what the manufacturer claims.

- the ability to change the energy intensity of the system by changing the number of fuel cartridges, which provides almost unlimited autonomy,

The ability to provide almost any reasonable energy consumption of the system by changing the capacity of the hydrogen storage,

- high energy intensity,

- tolerance to impurities in hydrogen,

But a thousand parts facilitate airflow and optimize cooling. Even more than its predecessor, this electric car demonstrates that the fuel cell is in the spotlight. A big challenge for the industry and our leaders. Meanwhile, it is very clever who will know which of the fuel cell or battery will prevail.

A fuel cell is an electrochemical energy conversion device that can generate electricity in the form of direct current by combining a fuel and an oxidizer in a chemical reaction to produce waste, typically fuel oxide.

- long service life,

- environmental friendliness and noiselessness of work.

Power supply systems based on hydrogen fuel cells for UAVs:

Installing fuel cells on unmanned vehicles instead of traditional batteries, it multiplies the flight duration, the payload weight, and improves reliability aircraft, expand the temperature range for the launch and operation of the UAV, lowering the border to -40 0С. Compared to internal combustion engines, fuel cell systems are silent, vibration-free, operate at low temperatures, are difficult to detect during flight, do not emit harmful emissions, and allow you to efficiently perform tasks from video surveillance to the delivery of payloads.

Each fuel cell has two electrodes, one of which is positive and the other negative, and the reaction that produces electricity occurs at the electrodes in the presence of an electrolyte that carries charged particles from electrode to electrode, while electrons circulate in the outer wires located between the electrodes to create electricity.

The fuel cell can generate electricity continuously as long as the required flow of fuel and oxidant is maintained. Some fuel cells produce only a few watts, while others can produce several hundred kilowatts, while smaller batteries are likely to be found in laptops and cell phones, but fuel cells are too expensive to become Small generators used to generate electricity for homes and businesses.

The composition of the power supply system for the UAV:

Economic dimensions of fuel cells

The use of hydrogen as a fuel source is costly. For this reason, hydrogen is now a non-economic source, in particular because other less expensive sources can be used. The costs of producing hydrogen can vary as they reflect the cost of the resources from which it is extracted.

Fuel sources for batteries

Fuel cells are generally classified into the following categories: hydrogen fuel cells, fossil fuel cells, metal fuel cells, and redox batteries. When hydrogen is used as a fuel source, chemical energy is converted to electricity during the reverse hydrolysis process to produce only water and heat as waste. A hydrogen fuel cell is very low, but can be more or less high in hydrogen production, especially if it is produced from fossil fuels.

• - a battery of fuel cells,
• - Li-Po buffer battery to cover short-term peak loads,
• - electronic control system ,
• - a fuel system consisting of a compressed hydrogen cylinder or a solid hydrogen source.

The fuel system uses high-strength, lightweight cylinders and gearboxes to maximize the supply of compressed hydrogen on board. It is allowed to use various standard sizes of cylinders (from 0.5 to 25 liters) with reducers providing the required hydrogen consumption.

Hydrogen batteries fall into two categories: low temperature and high temperature batteries, where high temperature batteries can also use fossil fuels directly. The latter are composed of hydrocarbons such as oil or gasoline, alcohol or biomass.

Other fuel sources in batteries include, but are not limited to, alcohols, zinc, aluminum, magnesium, ionic solutions, and many hydrocarbons. Other oxidizing agents include, but are not limited to, air, Chlorine, and chlorine dioxide. Currently, there are several types of fuel cells.

Characteristics of the power supply system for the UAV:

Portable Hydrogen Fuel Cell Chargers:

Portable chargers based on hydrogen fuel cells are compact devices, comparable in weight and dimensions to existing and actively used battery chargers in the world.

The ubiquitous portable technology in the modern world needs to be recharged regularly. Traditional portable systems are practically useless at subzero temperatures, and after fulfilling their function, they also require recharging using (electrical networks), which also reduces their efficiency and autonomy of the device.

Each dihydrogen molecule has 2 electrons. The H ion passes from the anode to the cathode and induces an electric current when an electron is transferred. What might an aircraft fuel cell look like? Today, tests are being carried out on airplanes to try and fly them using a lithium-ion hybrid fuel cell battery. The true gain of a fuel cell lies in its low weight integrity: it is lighter, which contributes to a reduction in aircraft mass and therefore fuel consumption.

But for now, flying in an airplane with a fuel cell is not possible because it still has many disadvantages. Fuel cell image. What are the disadvantages of a fuel cell? First of all, if hydrogen were widespread, using it in large quantities would be problematic. Indeed, it is available not only on Earth. It is found in oxygenated water, ammonia. Therefore, it is necessary to carry out electrolysis of water to obtain it, and this is not yet a widespread method.

Hydrogen fuel cell systems only require replacement of the compact fuel cartridge and the unit is immediately operational.

Characteristics of portable chargers:

Uninterruptible power supplies based on hydrogen fuel cells:

Guaranteed power supply systems based on hydrogen fuel cells are designed to organize backup power supply and temporary power supply. Guaranteed power supply systems based on hydrogen fuel cells offer significant advantages over traditional solutions for organizing temporary and backup power supply, using storage batteries and diesel generators.

Hydrogen is a gas and therefore difficult to contain and transport. Another risk associated with the use of hydrogen is the risk of explosion, as it is a flammable gas. what supplies the battery for its production on a large scale requires a different source of energy, be it oil, gas or coal, or nuclear energy, which makes its ecological balance significantly worse than kerosene and make a bunch of platinum, a metal, which is even rarer and more expensive than gold.

The fuel cell provides energy by oxidizing the fuel at the anode and reducing the oxidant at the cathode. The discovery of the fuel cell principle and the first laboratory implementations using sulfuric acid as an electrolyte are credited to chemist William Grove.

Uninterruptible Power System Specifications:

Fuel cell Is an electrochemical device, similar to a galvanic cell, but different from it in that substances for an electrochemical reaction are supplied to it from the outside - in contrast to the limited amount of energy stored in a galvanic cell or battery.

Indeed, fuel cells have some advantages: those that use dihydrogen and dioxide only emit water vapor: therefore it is a clean technology. There are several types of fuel cells, depending on the nature of the electrolyte, the nature of the fuel, direct or indirect oxidation, and the operating temperature.

The following table summarizes the main characteristics of these various devices. Several European programs are looking for other polymers, such as polybenzimidazole derivatives, that are more stable and cheaper. Battery compactness is also a constant challenge with membranes in the 15-50 micron range, porous carbon anodes and stainless steel bipolar plates. The lifespan can also be improved, since, on the one hand, traces of carbon monoxide of the order of a few ppm in hydrogen are real poisons for the catalyst, and on the other hand, control of water in the polymer is imperative.

Rice. one. Some fuel cells

Fuel cells convert the chemical energy of the fuel into electricity, bypassing ineffective combustion processes that go with large losses. They convert hydrogen and oxygen into electricity as a result of a chemical reaction. As a result of this process, water is formed and a large amount of heat is released. A fuel cell is very similar to a battery, which can be charged and then used up with stored electrical energy. The inventor of the fuel cell is believed to be William R. Grove, who invented it back in 1839. In this fuel cell, a sulfuric acid solution was used as an electrolyte, and hydrogen was used as a fuel, which was combined with oxygen in an oxidizing medium. Until recently, fuel cells were used only in laboratories and on spacecraft.

Unlike other generators of electricity, such as internal combustion engines or turbines that run on gas, coal, fuel oil, etc., fuel cells do not burn fuel. This means no noisy high pressure rotors, no loud exhaust noise, no vibrations. Fuel cells generate electricity through a silent electrochemical reaction. Another feature of fuel cells is that they convert the chemical energy of the fuel directly into electricity, heat and water.

Fuel cells are highly efficient and do not produce large amounts of greenhouse gases such as carbon dioxide, methane and nitric oxide. The only emissions produced by fuel cells are water in the form of steam and a small amount of carbon dioxide, which is not emitted at all if pure hydrogen is used as the fuel. Fuel cells are assembled into assemblies and then into separate functional modules.

Fuel cells have no moving parts (at least within the cell itself) and therefore do not obey Carnot's law. That is, they will have greater than 50% efficiency and are especially effective at low loads. Thus, fuel cell vehicles can (and have already been proven) more economical than conventional vehicles under real-world driving conditions.

The fuel cell generates a constant voltage electrical current that can be used to drive an electric motor, lighting fixtures, and other electrical systems in a vehicle.

There are several types of fuel cells that differ in the chemical processes used. Fuel cells are usually classified by the type of electrolyte they use.

Some types of fuel cells are promising for use as power plants for power plants, while others for portable devices or for driving cars.

1. Alkaline fuel cells (SHFC)

Alkaline fuel cell- this is one of the very first elements developed. Alkaline fuel cells (ALFC) are one of the most studied technologies used by NASA in the Apollo and Space Shuttle programs since the mid-1960s. Aboard these spaceships, fuel cells produce electricity and drinking water.

Alkaline fuel cells are one of the most efficient elements used to generate electricity, with power generation efficiency reaching up to 70%.

Alkaline fuel cells use an electrolyte, that is, an aqueous solution of potassium hydroxide contained in a porous stabilized matrix. The concentration of potassium hydroxide can vary depending on the operating temperature of the fuel cell, which ranges from 65 ° C to 220 ° C. The charge carrier in SHFC is a hydroxyl ion (OH-), which moves from the cathode to the anode, where it reacts with hydrogen, producing water and electrons. The water produced at the anode moves back to the cathode, again generating hydroxyl ions there. This series of reactions in the fuel cell produces electricity and, as a by-product, heat:

Reaction at the anode: 2H2 + 4OH- => 4H2O + 4e

Cathode reaction: O2 + 2H2O + 4e- => 4OH

General system response: 2H2 + O2 => 2H2O

The advantage of SHFCs is that these fuel cells are the cheapest in production, since the catalyst that is needed on the electrodes can be any of the substances that are cheaper than those that are used as catalysts for other fuel cells. In addition, SCHE operate at a relatively low temperature and are among the most efficient.

One of the characteristic features of SHFC is its high sensitivity to CO2, which can be contained in fuel or air. CO2 reacts with the electrolyte, quickly poisons it, and greatly reduces the efficiency of the fuel cell. Therefore, the use of SHTE is limited to closed spaces, such as space and underwater vehicles, they operate on pure hydrogen and oxygen.

2. Fuel cells based on molten carbonate (RKTE)

Fuel cells with molten carbonate electrolyte are high temperature fuel cells. The high operating temperature allows natural gas to be used directly without a processor fuel and low calorific value fuel gas for industrial processes and other sources. This process developed in the mid-60s of the twentieth century. Since then, production technology, performance and reliability have been improved.

The operation of RKTE is different from other fuel cells. These cells use an electrolyte from a mixture of molten carbonate salts. Currently, there are two types of mixtures in use: lithium carbonate and potassium carbonate or lithium carbonate and sodium carbonate. To melt carbonate salts and achieve a high degree of ion mobility in the electrolyte, fuel cells with molten carbonate electrolyte operate at high temperatures (650 ° C). The efficiency varies between 60-80%.

When heated to 650 ° C, the salts become a conductor for carbonate ions (CO32-). These ions travel from the cathode to the anode, where they combine with hydrogen to form water, carbon dioxide and free electrons. These electrons are channeled back to the cathode through an external electrical circuit, generating electrical current and heat as a by-product.

Anode reaction: CO32- + H2 => H2O + CO2 + 2e

Cathode reaction: CO2 + 1 / 2O2 + 2e- => CO32-

General reaction of the element: H2 (g) + 1 / 2O2 (g) + CO2 (cathode) => H2O (g) + CO2 (anode)

The high operating temperatures of molten carbonate electrolyte fuel cells have certain advantages. The advantage is the ability to use standard materials (stainless steel sheet and nickel catalyst on the electrodes). The waste heat can be used to generate high pressure steam. High reaction temperatures in the electrolyte also have their advantages. The use of high temperatures takes a long time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. These characteristics allow the use of fuel cell installations with molten carbonate electrolyte under constant power conditions. High temperatures prevent carbon monoxide damage to the fuel cell, poisoning, etc.

Molten carbonate electrolyte fuel cells are suitable for use in large stationary installations. Thermal power plants with an output electric power of 2.8 MW are industrially produced. Installations with an output power of up to 100 MW are being developed.

3. Fuel cells based on phosphoric acid (FCTE)

Fuel cells based on phosphoric (orthophosphoric) acid became the first fuel cells for commercial use. This process was developed in the mid 60s of the twentieth century, tests have been carried out since the 70s of the twentieth century. As a result, stability and performance have been increased and cost has been reduced.

Fuel cells based on phosphoric (orthophosphoric) acid use an electrolyte based on phosphoric acid (H3PO4) with a concentration of up to 100%. The ionic conductivity of phosphoric acid is low at low temperatures, therefore these fuel cells are used at temperatures up to 150-220 ° C.

The charge carrier in this type of fuel cell is hydrogen (H +, proton). A similar process occurs in fuel cells with a proton exchange membrane (MOPTE), in which the hydrogen supplied to the anode is separated into protons and electrons. Protons travel through the electrolyte and combine with oxygen from the air at the cathode to form water. Electrons are channeled through an external electrical circuit, generating an electrical current. Below are the reactions that generate electricity and heat.

Reaction at the anode: 2H2 => 4H + + 4e

Cathode reaction: O2 (g) + 4H + + 4e- => 2H2O

General reaction of the element: 2H2 + O2 => 2H2O

The efficiency of fuel cells based on phosphoric (orthophosphoric) acid is more than 40% when generating electrical energy. With combined heat and power generation, the overall efficiency is around 85%. In addition, given the operating temperatures, the waste heat can be used to heat water and generate steam at atmospheric pressure.

The high performance of thermal power plants on fuel cells based on phosphoric (orthophosphoric) acid in the combined production of heat and electricity is one of the advantages of this type of fuel cells. The plants use carbon monoxide with a concentration of about 1.5%, which significantly expands the choice of fuel. Simple design, low electrolyte volatility and increased stability are also advantages of such fuel cells.

Thermal power plants with an output electric power of up to 400 kW are industrially produced. Installations with a capacity of 11 MW have been tested accordingly. Installations with an output power of up to 100 MW are being developed.

4. Fuel cells with a proton exchange membrane (MOPTE)

Fuel cells with proton exchange membrane are considered the best type of fuel cells for generating power for vehicles, which can replace gasoline and diesel internal combustion engines. These fuel cells were first used by NASA for the Gemini program. Installations on MOPTE have been developed and shown with a capacity of 1 W to 2 kW.

The electrolyte in these fuel cells is a solid polymer membrane (thin plastic film). When impregnated with water, this polymer allows protons to pass through but does not conduct electrons.

The fuel is hydrogen, and the charge carrier is a hydrogen ion (proton). At the anode, a hydrogen molecule is split into a hydrogen ion (proton) and electrons. Hydrogen ions pass through the electrolyte to the cathode, while electrons move around the outer circle and produce electrical energy. Oxygen, which is taken from the air, is fed to the cathode and combines with electrons and hydrogen ions to form water. The following reactions take place on the electrodes: Reaction at the anode: 2H2 + 4OH- => 4H2O + 4e Reaction at the cathode: O2 + 2H2O + 4e- => 4OH Total cell reaction: 2H2 + O2 => 2H2O Compared to other types of fuel cells, fuel cells a proton exchange membrane produces more energy for a given volume or weight of a fuel cell. This feature allows them to be compact and lightweight. In addition, the operating temperature is less than 100 ° C, which allows for quick start-up of operation. These characteristics, as well as the ability to quickly change energy output, are just a few of what makes these fuel cells a prime candidate for vehicle use.

Another advantage is that the electrolyte is solid and not liquid. It is easier to keep gases at the cathode and anode with a solid electrolyte, so such fuel cells are cheaper to manufacture. When using a solid electrolyte, there are no such difficulties as orientation and fewer problems due to the occurrence of corrosion, which increases the life of the cell and its components.

5. Solid oxide fuel cells (SOFC)

Solid oxide fuel cells are the fuel cells with the highest operating temperature. The operating temperature can be varied from 600 ° C to 1000 ° C, which allows different types of fuel to be used without special pre-treatment. To handle these high temperatures, the electrolyte used is a thin, ceramic-based solid metal oxide, often an alloy of yttrium and zirconium, which is a conductor of oxygen (O2-) ions. The technology of using solid oxide fuel cells has been developing since the late 1950s and has two configurations: planar and tubular.

Solid electrolyte provides a hermetically sealed transition of gas from one electrode to another, while liquid electrolytes are located in a porous substrate. The charge carrier in this type of fuel cell is an oxygen ion (O2-). At the cathode, oxygen molecules from the air are separated into an oxygen ion and four electrons. Oxygen ions pass through the electrolyte and combine with hydrogen to form four free electrons. Electrons are channeled through an external electrical circuit, generating electrical current and waste heat.

Reaction at the anode: 2H2 + 2O2- => 2H2O + 4e

Cathode reaction: O2 + 4e- => 2O2-

General reaction of the element: 2H2 + O2 => 2H2O

The efficiency of electric power generation is the highest of all fuel cells - about 60%. In addition, the high operating temperatures enable combined heat and power generation to generate high pressure steam. Combining a high-temperature fuel cell with a turbine makes it possible to create a hybrid fuel cell to increase the efficiency of electric power generation by up to 70%.

Solid oxide fuel cells operate at very high temperatures (600 ° C-1000 ° C), which takes a long time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. At such high operating temperatures, a converter is not required to recover hydrogen from the fuel, which allows the thermal power plant to operate with relatively unclean fuels resulting from the gasification of coal or waste gases and the like. Also, this fuel cell is excellent for high power operation, including industrial and large central power plants. Modules with an output electrical power of 100 kW are commercially produced.

6. Fuel cells with direct methanol oxidation (POMTE)

Fuel cells with direct methanol oxidation They are successfully used in the field of power supply of mobile phones, laptops, as well as for the creation of portable power sources, which is what the future use of such elements is aimed at.

The design of fuel cells with direct methanol oxidation is similar to the design of fuel cells with a proton exchange membrane (MOPTE), i.e. a polymer is used as an electrolyte, and a hydrogen ion (proton) is used as a charge carrier. But liquid methanol (CH3OH) is oxidized in the presence of water at the anode with the release of CO2, hydrogen ions and electrons, which are directed along an external electrical circuit, while an electric current is generated. Hydrogen ions pass through the electrolyte and reacts with oxygen from the air and electrons from the external circuit to form water at the anode.

Reaction at the anode: CH3OH + H2O => CO2 + 6H + + 6e Reaction at the cathode: 3 / 2O2 + 6H + + 6e- => 3H2O General reaction of the element: CH3OH + 3 / 2O2 => CO2 + 2H2O The development of such fuel cells was carried out from the beginning90- x years of the twentieth century, and their power density and efficiency were increased to 40%.

These elements were tested in a temperature range of 50-120 ° C. Because of the low operating temperatures and the lack of the need for a converter, such fuel cells are the best candidate for applications in mobile phones and other consumer goods, as well as in automobile engines. Their advantage is also small size.

7. Polymer electrolyte fuel cells (PETE)

In the case of polymer electrolyte fuel cells, the polymer membrane consists of polymer fibers with water regions in which the conductivity of water ions exists. H2O + (proton, red) is attached to the water molecule. Water molecules pose a problem due to their slow ion exchange. Therefore, a high concentration of water is required both in the fuel and at the outlet electrodes, which limits the operating temperature to 100 ° C.

8. Solid acid fuel cells (TKTE)

In solid acid fuel cells, the electrolyte (CsHSO4) does not contain water. The operating temperature is therefore 100-300 ° C. Rotation of oxyanions SO42-allows protons (red) to move as shown in the figure. Typically, a solid acid fuel cell is a sandwich in which a very thin layer of a solid acid compound is sandwiched between two tightly compressed electrodes to ensure good contact. When heated, the organic component evaporates, leaving through the pores in the electrodes, retaining the ability of multiple contacts between the fuel (or oxygen at the other end of the cells), electrolyte and electrodes.

9. Comparison of the most important characteristics of fuel cells

Fuel cell characteristics

Fuel cell type	Working temperature	Power generation efficiency	Fuel type	Scope of application
				Medium and large installations
			Pure hydrogen	installations
			Pure hydrogen	Small installations
			Most hydrocarbon fuels	Small, medium and large installations
				Portable installations
			Pure hydrogen	Space investigating
			Pure hydrogen	Small installations

10. Use of fuel cells in cars

History

The first element was made, it seems, from a lead from a Russian (this is important), a simple pencil, and the body was a beer cork. All this was heated on a kitchen stove. The electrolyte was Digger pipe-cleaning powder, composed of NaOH, according to the label. Since I managed to get some kind of current, I thought that, probably, such an element could really work. The cans started to leak at the seams (the solder was eroded by the lye), and I don't even remember the results. For a more serious experience, I bought a stainless steel crook. However, nothing happened with her. Not only was the voltage only 0.5 volts, it was also directed in the wrong direction. It also turned out that the embers from pencils are very fond of falling apart into their component parts. Apparently, they are not made of a solid graphite crystal, but are glued together from dust. The same fate befell the rods from the AA batteries. Also, brushes from some electric motors were bought, but the places where the lead wire enters the brush quickly fell into disrepair. In addition, one pair of brushes, as it turned out, contained copper or some other metal (this happens with brushes).

Hardly scratching the back of my head, I decided that, for reliability, it would be better to make a vessel of silver, and a coal - according to the technology described by Jacot, i.e., by sintering. Silver costs moderate money (prices fluctuate, but somewhere on the order of 10-20 rubles per gram). I have come across tea that is much more expensive.

It is known that silver is stable in NaOH melt, while iron gives ferrates, for example, Na2FeO4. Since in general iron has a variable valence, then its ions can cause a "short circuit" in the element, at least in theory. Therefore, I decided to start with checking the case of silver, as it is simpler. First, a cupronickel silver-plated spoon was bought, and when tested with brushes, 0.9V of an open circuit with the desired polarity was immediately obtained, as well as a fairly large current. Subsequently (not practically, but theoretically) it turned out that silver can also dissolve in alkali in the presence of sodium peroxide Na2O2, which is formed in some quantities by blowing air. Whether it will be in the element or protected by carbon, silver is safe - I don't know.

The spoon did not last long. The silver layer swelled and it stopped working. Cupronickel is unstable in alkali (like most materials existing in the world). After that, I made a special cup from a silver coin, on which a record power of 0.176 watts was obtained.

All this was done in an ordinary city apartment, in the kitchen. I never burned myself, did not start a fire, and only once spilled molten alkali on the stove (the enamel immediately corroded). The simplest tool was used. If it turns out to find out the correct type of iron and the correct composition of the electrolyte, then every not quite armless man can make such an element on his knee.

In 2008, several "correct types of iron" came to light. For example, food stainless steel, tin cans, electrical steels for magnetic circuits, as well as low-carbon steels - st1ps, st2ps. The less carbon, the better the performance. Stainless steel seems to work worse than pure iron (by the way, it is much more expensive). "Norwegian sheet" iron, also known as Swedish, is iron that was made in a critical way in Sweden on charcoal and contained no more than 0.04% carbon. Nowadays, this low carbon content can only be found in electrical steels. Probably the best way to make cups is stamped from electrical steel sheet.

Making a silver cup

In 2008, it turned out that the iron cup also works well, so I remove everything about the silver cup. It was interesting, but now it's irrelevant.

You can try to use graphite. But I didn't have time. I begged the driver's aunt for a trim for the horns of the trolleybus, but that was already at the end of my experimental epic. You can also try brushes from motors, but they often come with copper, which violates the purity of the experiment. I had two options for brushes, one turned out to be with copper. Pencils do not work because they have a small surface area and are inconvenient to draw current from them. Battery rods in alkali fall apart
(something happens to the binder). Generally speaking, graphite is the worst fuel for a cell because it is the most chemically stable. Therefore, we make the electrode "honestly". We take charcoal (I bought birch charcoal for barbecue at the supermarket), grind as small as possible (I ground it first in a porcelain mortar, then bought a coffee grinder). In industry, electrodes are made from several coal fractions by mixing them with each other. Nothing prevents you from doing the same. The powder is fired to increase its electrical conductivity: it needs to be heated for a few minutes to the highest possible temperature (1000 or more). Naturally, without access to air.

For this I made a forge from two cans nested inside each other. Pieces of dry clay are piled between them for thermal insulation. The bottom of both cans is punctured to allow air to blow. The inner can is filled with coals (which act as fuel), among them is a metal box - "crucible", I also rolled it out of tin from a tin can. Coal powder wrapped in a paper bag is stuffed into the box. There should be a gap between the coal roll and the walls of the "crucible". It is covered with sand so that there is no air access. The coals are set on fire, then blowing is done through the holes in the bottom with an ordinary hair dryer. All this is quite fire hazardous - sparks fly. You need goggles, and you also need to look so that there are no curtains, barrels of gasoline and other fire hazardous items nearby. It would be better, for good, to do such things somewhere on a green lawn during the rainy season (in between the rains). Sorry, but I'm too lazy to draw this whole structure. I think you can guess without me.

Next, a certain amount of sugar is added to the burnt powder by eye (probably from a third to a half). It's a binder. Then - a little bit of water (when I had dirty hands and were too lazy to turn on the tap, I just spit into it and added beer instead of water, I don't know how much it matters; it is quite possible that organics are important. All this is thoroughly mixed in The result should be a plastic mass. From this mass you need to form an electrode. The better you press it, the better. I took a plugged piece of the tube and hammered the coal into the tube with a smaller tube, using a hammer. So that the product does not fall apart when removed from the tube. , before stuffing, I inserted several rims of paper into the pipe. The plug should be removable, and even better - if the pipe is cut along and connected with clamps. Then after pressing, you can simply disconnect the clamps and get the coal blank intact. will extrude the finished workpiece from
pipes (in this case, it may fall apart). My coal had a diameter of 1.2-1.5 cm and a length of 4-5 cm.

The finished form is dried. To do this, I turned on the gas stove on a very small fire, put an empty tin can upside down on it and put a coal on the bottom. Drying should be slow enough so that water vapor does not break the workpiece. After all the water has evaporated, the sugar will begin to "boil". It will turn into caramel and glue the pieces of coal together.

After cooling down, you need to drill a longitudinal (along its axis of symmetry) round hole in the coal, into which the discharge electrode will be inserted. Hole diameter - I don't remember, it seems 4 mm. With this procedure, everything can already be covered, because the structure is fragile. I first drilled with a 2 mm drill, then carefully (manually) expanded with 3 and 4 mm drills, or even with a file, I don’t remember exactly. In principle, this hole can be made already at the molding stage. But this -
nuances.

After everything is dried and drilled, you need to fire it. The general meaning is that with a sufficiently smooth set of temperature, the ember should be subjected to strong and uniform heating without air access for a while (about 20 minutes). You need to heat it up gradually, cool it down too. Temperature - the higher the better. More than 1000 is desirable. I had
orange (closer to white) heating of iron in an improvised furnace. Industrial electrodes are fired for many days, with a very smooth supply-removal of heat. After all, this is, in fact, ceramics, which is fragile. I cannot guarantee that the ember will not crack. I did everything by sight. Some of the coals were cracked right after the start of exploitation.

So, the coal is ready. It should have as little resistance as possible. When measuring resistance, do not touch the coal with the tester's needles, but take two stranded wires, lean them against the sides of the coal (not to the ends of the rod, but simply in diameter) and press firmly with your fingers (just so as not to crack), see figure, figure the pink amorphous mass is the fingers gripping the wires.

If the resistance is 0.3-0.4 ohms (this was on the verge of sensitivity of my tester), then this is a good coal. If more than 2-3 ohms, then it is bad (the power density will be small). If the ember fails, you can repeat the firing.

After firing is done, we make a discharge electrode. This is a strip of silver or iron - 2008 a length equal to two times or slightly less than the length of the coal,
width - two diameters of the hole. Thickness - let's say 0.5 mm. From it you need to roll a cylinder, the outer diameter of which is
hole diameter. But the cylinder will not work, because the width is too small, you will get a cylinder with a longitudinal slot. This slot is important to compensate for thermal expansion. If you make a full cylinder, then the silver will break the ember when heated.
Insert the "cylinder" into the coal. You need to make it fit tightly into the hole. There are two sides to this: excessive force will break the ember; if the force is weak, there will be insufficient contact (it is very important). See picture.

This design was not born immediately, it seems to me more perfect than those clamps that are drawn in Jaco's patent. First, with such a contact, the current does not flow along, but along the radius of the cylindrical coal, which can significantly reduce electrical losses. Secondly, metals have a higher coefficient of thermal expansion than coal, so the contact of coal with the metal clamp weakens when heated. In my case, the contact is strengthened or retains its strength. Thirdly, if the lead electrode is not made of silver, then the carbon protects it from oxidation. Give me a patent soon!

Now you can measure the resistance again, one of the poles will be a current-carrying electrode. By the way, my tester has 0.3 ohm - this is already the sensitivity limit, so it is better to pass a current of a known voltage and measure its strength.

Air supply

We take a steel rod from a large-capacity ballpoint pen. It is desirable - empty. We remove the block with the ball from it - just an iron tube remains. We carefully remove the remnants of the paste (I didn’t do it very well and the paste then charred, which made it difficult to live). First, this is done with water, and then it is better to ignite the rod several times in the flame of the burner. Pyrolysis of the ink will occur, leaving coal that can be wiped out.

Next, we find some other tube to connect this rod (it will be heated) with the PVC-shnoy tube leading from the aquarium compressor, which is used to condition the fish. Everything should be tight enough. We put an adjustable clamp on the PVC pipe, because even the weakest compressor gives too much air. Ideally, you need to make a silver, not steel tube, and I even succeeded, but I could not ensure a tight connection between the silver tube and the PVC shnoy. The intermediate tubes strongly etched the air (due to the same thermal gaps), so I ended up settling on a steel rod. Of course, this problem is solvable, but you just had to spend time and effort on it and choose the appropriate tube for the situation. In general, in this part I deviated greatly from Jacot's patent. I could not make such a rose, as drawn by him (and to be honest, I did not consider its design well enough then).

A small digression should be made at this point to discuss how wrongly Jacot presented the work of his element. Obviously, oxygen goes into ionic form somewhere at the cathode, according to the formula O2 + 4e- = 2O2-, or some similar reaction, where oxygen is reduced and combines with something. That is, it is important to provide a triple contact of air, electrolyte and cathode. This can occur when air bubbles come into contact with the metal of the atomizer and the electrolyte. That is, the larger the total perimeter of all the holes in the atomizer, the greater the current must be. Also, if you make a cup with slanted edges, then the triple contact surface can also increase, see fig.

Another option is when dissolved oxygen is reduced at the cathode. In this case, the area of ​​the triple contact does not really matter, but you just need to maximize the surface area of ​​the bubbles in order to accelerate the dissolution of oxygen. True, in this case it is not clear why dissolved oxygen does not oxidize coal directly, without an electrochemical reaction (working "past" the electrical circuit). Apparently, in this case, the catalytic properties of the cup material are important. Okay, it's all lyrics. In any case, you need to divide the jet into small bubbles. The attempts I have made to do this have not been particularly successful.

To do this, it was necessary to make thin holes with which a lot of problems turned out.

First, thin holes quickly become clogged. iron corrodes, rust and remains of coal (remember that there was once a paste from the handle) fall out of the rod and plug the holes.
Secondly, the holes are unequal in size and it is difficult to force air to flow from all the holes at the same time.
Third, if the two holes are side by side, then there is a bad tendency for the bubbles to merge even before they are torn off.
Fourthly, the compressor delivers air unevenly and this also somehow affects the size of the bubbles (apparently, one bubble pops up at one push). All this can be easily observed by pouring water into a transparent jar and testing the spray in it. Of course, alkali has a different viscosity and surface tension coefficient, so you have to act at random. I have not been able to overcome these problems and plus to this, the problem of air leaks due to thermal gaps. These leaks prevented the sprayer from starting to operate as surface tension forces had to be overcome. It was here that the disadvantages of the clamps fully manifested themselves. No matter how you tighten them, when heated, they still weaken. In the end, I switched to the simplest ballpoint rod sprayer that only produced one stream of bubbles. Apparently, in order to do this in a normal way, you need to carefully get rid of leaks, supply air under significant pressure (more than that created by the aquarium compressor) and through small holes.

This part of the design has been worked out frankly badly for me ...

Assembly

Everything. Putting it all together. It is necessary to install everything on the clamps so that
1. There was no short circuit across the supporting structure.
2. The corner did not touch the air blowing tube, as well as the walls
a cup. This will be difficult because the gaps are small, the clamps are flimsy, and the alkali will bubble when the cell is in operation. Also, the Archimedean force will act, which will shift everything where it is not necessary, and the surface tension force, which attracts the ember to other objects. The silver will become soft when heated. Therefore, in the end, I held the ember with pliers by the end of the lead electrode. It was bad. For normal operation, you still need to make a lid (apparently, only from porcelain - the clay gets soaked in alkali and loses its strength, maybe you can use the fired clay). The idea of ​​how to make this lid is in Jacot's patent. The main thing is that it should hold the coal quite well, because even with a slight bias, it will touch the cup at the bottom. For this, it must have a great height. I failed to find such a porcelain lid, to make a ceramic one from clay - too (everything that I tried to do from clay quickly cracked, apparently, I somehow did not burn it that way). The only little trick is to use a metal cover and layer the path of even poorly fired clay as thermal insulation. This path is also not so easy.

In short, the design of the element was also useless for me.

It's also a good idea to prepare a tool with which you can get a piece of coal, which can fall off the electrode and fall into the alkali. A piece of coal may fall off and fall into the alkali, then there will be a short circuit. I had a bent steel clip as such a tool, which I held with pliers. We bring the wires - one to the handle, the other to the outlet electrode. You can solder, although I used two metal plates and screwed them with screws (everything from a children's metal construction set). The main thing is to understand that the whole structure operates at low voltage and all connections must be made well. We measure the resistance in the absence of electrolyte between the electrodes - we make sure that it is large (at least 20 ohms). We measure the resistance of all connections - we make sure that they are small. Putting together a circuit with a load. For example, a resistance of 1 ohm and an ammeter connected in series. Testers have a low resistance of the ammeter only in the mode of measuring ampere units, it is advisable to find out in advance. You can either turn on the ampere units change mode (the current will be from 0.001 to 0.4 A), or instead of a series-connected ammeter, turn on a voltmeter in parallel (the voltage will be from 0.2 to 0.9 V). It is advisable to provide for the possibility of changing conditions during the experiment in order to measure the voltage of the open circuit, the short-circuit current and the current with a load of 1 ohm. And it is better if the resistance can also be changed: 0.5 ohm, 1 ohm and 2 ohm to find the one at which the maximum power will be reached.

We turn on the compressor from the aquarium and wrap the clamp so that the air goes barely (and, by the way, the operability of the supply pipeline must be checked by immersing it in water. Since the density of the alkali is 2.7, it must be immersed to a corresponding greater depth. Full tightness is not necessary, the main thing is that even at such a depth something gurgles from the end of the tube.

Precautionary measures

Next comes the work with the alkali melt. How to explain what an alkali melt is? Did you get soap in your eyes? Unpleasant, right? So, melt NaOH is also soap, only heated to 400 degrees and hundreds of times more caustic.

Protective measures when working with molten alkali are strictly required!

Primarily, good safety glasses are strictly necessary... I am short-sighted, so I wore two glasses - plastic protective on top, and glass under them. Safety glasses must protect from splashing not only from the front, but also from the side. In such ammunition, I felt safe. Despite the protective glasses, it is not recommended to bring your face closer to the device at all.

In addition to the eyes, it is necessary to protect the hands. I did everything very neatly, so in the end I had already "mastered" and worked in a T-shirt. This is useful, because sometimes even the smallest splashes of alkali that get on your hands cause a burn, which does not allow you to forget what substance you are dealing with for several days.

But of course, there were gloves on my hands. First, rubber household (not the thinnest), and on top of them - pimply rag pimples stuck out from the back of the palm. I moistened them with water so that I could handle hot objects. In such a pair of gloves, hands are more or less protected. But care must be taken that the outer gloves are never too wet. A drop of water entering the electrolyte immediately boils, and the electrolyte splashes very well. If this happens (and this happened to me three times), problems arise with the respiratory system. In these cases, I immediately held my breath without completing the inhalation (kayaking practice helps not to panic in such situations), and dumped out of the kitchen to pick up and greet.

In general, good ventilation is needed to protect the respiratory system during the experiment. In my case, it was just a draft (it was in the summer). But ideally it should be a hood or open air.

Since alkali splashes are unavoidable, everything in the immediate vicinity of the glass is covered with alkali to one degree or another. If you handle it with your bare hands, you can get burned. You need to rinse everything after completing the experiment, including gloves.

Even in case of a burn, I always had a container with water and a container with diluted vinegar prepared nearby to neutralize alkali in case of a severe burn. Vinegar has never come in handy, fortunately and I can't say if it's worth using it at all. In case of burns, wash off the alkali immediately with plenty of water. There is also a folk remedy for burns - urine. It seems to help too.

Actually working with the element

Pour dry NaOH into a glass (I bought Digger for pipe cleaning). You can add MgO and other ingredients like CaCO3 (tooth powder or chalk) or MgCO3 (I had MgO mined by friends). We light the burner and heat it up. Since NaOH is extremely hygroscopic, you need to do this right away (and close the bag of NaOH tightly). It would be nice to make sure that the glass is surrounded by heat from all sides - the current is VERY temperature dependent. That is, to make an impromptu combustion chamber and direct the burner flame into it (you also need to make sure that the canister at the burner does not explode, in my opinion these burners are poorly made from this point of view, as I already wrote, for this you need to hot gases did not get on the can, and it is better to keep it in a normal position, and not "upside down").
Sometimes it is convenient to bring the burner flame from above, but this is after everything has melted. Then, at the same time, the discharge tube is heated, the discharge electrode (and the coal through it), the top of the glass, where there are most of the air bubbles). If my memory serves me, the greatest result was obtained in this way.

After some time, the alkali will begin to melt and its volume will decrease. It is necessary to add powder so that the glass is 2/3 full in height (alkali will leak out due to capillary and splashing). The air supply pipe did not work well for me (due to thermal expansion, the gaps and leaks will increase, and due to good heat dissipation, the alkali in it can solidify). Sometimes the air stopped flowing altogether. To fix this, I did the following:
1. Blowing. (temporary neat increase in air supply)
2. Rise. (there will be less pressure and the air will displace the alkali column from
pipes)
3. Warming up (take it out of the glass and heat it up with a burner so that the alkali inside the sprayer melts).

In general, the cell starts to work well at red heat (the alkali starts to glow). At the same time, foam starts to go (this is CO2), and pops are heard with flashes (whether it is hydrogen, or CO is burning out, I still do not understand).
I managed to achieve a maximum power of 0.025 W / cm2 or 0.176 W in total from the element, with a load resistance of 1.1 Ohm. At the same time, I measured the current with an ammeter. And it was possible to measure the voltage drop across the load.

Electrolyte degeneration

Element has a bad side reaction

NaOH + CO2 = Na2CO3 + H2O.

That is, after some time (tens of minutes) everything will freeze (the melting temperature of soda - I don't remember, but about 800). For some time this can be overcome by adding more alkalis, but in the end it doesn't matter - the electrolyte will solidify. To combat this, see other pages on this site, starting with the page about UTE. Generally speaking, you can use NaOH, regardless of this problem, as Jacot wrote about in his patent. Since there are ways to get NaOH from Na2CO3. For example, displacement by quicklime by the reaction Na2CO3 + CaOH = 2NaOH + CaCO3, after which CaCO3 can be calcined and you will get CaO again. True, this method is very energy-intensive and the overall efficiency of the element will drop very much, and the complexity will increase. Therefore, I think that you still need to look for a stable electrolyte composition, which was found in SARA. It is quite possible that this can be done by finding SARA patent applications in the database of the US Patent Office (http://www.uspto.gov), especially since they could have become patents already granted in the past. But my hands have not yet reached. Actually, this idea itself appeared only during the preparation of these materials. Apparently, soon I will do it.

Results, thoughts and conclusions

Here I may repeat myself a little. You can start with iron instead of silver. When I tried to use the rogue
made of stainless steel, I did it badly. Now I understand that the first reason for this is the low temperature and the large gap between the electrodes. In his article, Jacques writes that poor work with iron is due to the fact that oil burns to the iron and a second carbon electrode is formed, so you need to very carefully clean the iron from the slightest traces of oil, and also use iron
low carbon. Maybe so, but I still think that there is another, more important reason. Iron is an element of variable valence. It dissolves and forms a "short circuit". This is also supported by the color change. When using silver, the color of the electrolyte does not change (silver is the most resistant metal to the action of molten alkalis). At
using iron, the electrolyte turns brown. When using silver, the open circuit voltage reaches 0.9V and higher. When using hardware - much less (I don't remember exactly, but no more than 0.6V). As for what hardware you need to use in order for everything to work well, there is another page. A little more - about the water vapor, which SARA writes about. On the one hand, it is good for everyone (in theory): it does not allow iron to go into solution (the decomposition reaction of ferrates is known alkali metals hot water, something like Na2FeO4 + H2O = 2NaOH + Fe2O3) and seems to shift the equilibrium in a bad side reaction. I looked at the thermodynamics of the reaction NaOH + CO2 = Na2CO3 + H2O using the online program F * A * C * T (http://www.crct.polymtl.ca/FACT/index.php) At all temperatures, the equilibrium in it is very is strongly shifted to the right, i.e., water is unlikely to significantly displace carbon dioxide from the compound with sodium oxide. It is possible that the situation changes in the NaOH-Na2CO3 alloy, or a kind of aqueous solution forms, but I do not know how to find out. I think that in this case, practice is the criterion of truth.

The main thing that can be encountered when conducting experiments with steam is condensation. If somewhere along the road from the place where water enters the air line, the temperature of any wall drops below 100C, the water can condense, and then, with the air flow, get into the alkali in the form of a droplet. This is very dangerous and should be avoided with all your might. It is especially dangerous that the temperature of the walls is not so easy to measure. I myself have not tried to do anything with steam.

In general, of course, you need to carry out such work not in an apartment, but, at least, in the country, and immediately make an element of a larger size. To do this, of course, you will need a larger furnace for firing, a large “stove” for heating the element, and more raw materials. But it will be much more convenient to work with all the details. This is especially true of the device of the element itself, which I did not have a cover. Making a large lid is much easier than making a small one.

About silver. Silver, of course, is not that cheap. But if you make the silver electrode thin enough, the silver cell can be cost effective. For example, suppose we managed to make an electrode with a thickness of 0.1 mm. With the plasticity and malleability of silver, this will be easy (silver can be pulled through rolls into a very thin foil and I even wanted to do this, but there were no rolls). With a density of about 10g / cm ^ 3, one cubic centimeter of silver costs about 150 rubles. It will give 100 square centimeters of the electrode surface. You can get 200cm ^ 2 if you take two flat coals and place a silver plate between them. With the power density achieved by me at 0.025W / cm ^ 2, the power is 5 watts or 30 rubles per watt, or 30,000 rubles per kilowatt. Due to the simplicity of the design, the remaining components of the kilowatt element (stove, air pump) can be expected to be significantly cheaper. In this case, the body can be made of porcelain, which is relatively resistant to alkali melt. As a result, it will not be too expensive, even in comparison with low-power gasoline power plants. And solar panels with wind turbines and thermoelectric generators are resting far behind. To further reduce the price, you can try to make a vessel out of silver-plated copper. In this case, the silver layer will be 100-1000 times thinner. True, my experiments with cupronickel spoon ended unsuccessfully, so it is not clear how long the silver coating will be. That is, even the use of silver opens up pretty good prospects. The only thing that can be unsuccessful here is if the silver is not persistent enough.

More about the materials of the case. Allegedly, during the operation of the element, sodium peroxides are of great importance, for example, Na2O2, which should arise when air is blown into NaOH. At high temperatures, peroxide corrodes almost all substances. Experiments were carried out to measure the weight loss of crucibles made of various materials, which contained a sodium peroxide melt. The most resistant was zirconium, followed by iron, then nickel, then porcelain. Silver did not make it to the top four. Unfortunately, I don't remember exactly how stable silver is. There it was also written about the good resistance of Al2O3 and MgO. But the second place, which is iron, instills optimism.

That, in fact, is all.

A fuel cell is an electrochemical energy conversion device that chemically converts hydrogen and oxygen into electricity. As a result of this process, water is formed and a large amount of heat is generated. A fuel cell is very similar to a battery, which can be charged and then used up with stored electrical energy.
The inventor of the fuel cell is considered to be William R. Grove, who invented it back in 1839. In this fuel cell, a solution of sulfuric acid was used as an electrolyte, and hydrogen was used as a fuel, which combined with oxygen in an oxidizing medium. It should be noted that until recently, fuel cells were used only in laboratories and on spacecraft.
In the future, fuel cells will be able to compete with many other systems for converting energy (including a gas turbine in power plants) internal combustion engines in a car and electric batteries in portable devices. Internal combustion engines burn fuel and use the pressure created by the expansion of combustion gases to perform mechanical work. Batteries store electrical energy, converting it to chemical energy, which can be converted back to electrical energy if needed. Fuel cells are potentially very efficient. Back in 1824, the French scientist Carnot proved that the compression-expansion cycles of an internal combustion engine cannot provide the efficiency of conversion of thermal energy (which is the chemical energy of the burning fuel) into mechanical energy above 50%. A fuel cell has no moving parts (at least within the cell itself) and therefore do not obey Carnot's law. Naturally, they will have more than 50% efficiency and are especially effective at low loads. Thus, fuel cell vehicles are poised to become (and have already proven) more fuel efficient than conventional vehicles under real-world driving conditions.
The fuel cell generates a constant voltage electric current that can be used to drive the electric motor, lighting devices and other electrical systems in the vehicle. There are several types of fuel cells, differing in the chemical processes used. Fuel cells are usually classified by the type of electrolyte they use. Some types of fuel cells are promising for use as power plants for power plants, while others may be useful for small portable devices or for driving cars.
An alkaline fuel cell is one of the earliest developed cells. They have been used in the US space program since the 1960s. Such fuel cells are very susceptible to contamination and therefore require very pure hydrogen and oxygen. In addition, they are very expensive and therefore this type of fuel cell is unlikely to find widespread use in automobiles.
Fuel cells based on phosphoric acid can be used in stationary installations of low power. They operate at a fairly high temperature and therefore take a long time to warm up, which also makes them ineffective for use in automobiles.
Solid oxide fuel cells are better suited for large stationary power generators that could power factories or communities. This type of fuel cell operates at very high temperatures (around 1000 ° C). The high operating temperature creates certain problems, but on the other hand, there is an advantage - the steam produced by the fuel cell can be sent to the turbines to generate more electricity. In general, this improves the overall efficiency of the system.
One of the most promising systems is the Protone Exchange Membrane Fuel Cell (PEMFC). At the moment, this type of fuel cell is the most promising because it can propel cars, buses and other vehicles.

Chemical processes in a fuel cell

Fuel cells use an electrochemical process to combine hydrogen with oxygen from the air. Like batteries, fuel cells use electrodes (solid electrical conductors) in an electrolyte (electrically conductive medium). When hydrogen molecules come into contact with the negative electrode (anode), the latter are split into protons and electrons. Protons travel through the proton exchange membrane (PEM) to the positive electrode (cathode) of the fuel cell, producing electricity. There is a chemical combination of hydrogen and oxygen molecules with the formation of water as a by-product of this reaction. The only emission from a fuel cell is water vapor.
The electricity produced by the fuel cells can be used in a vehicle's electrical transmission (consisting of an electrical converter and an AC induction motor) to generate mechanical energy to drive the vehicle. The work of the electric power converter is to convert the direct electric current produced by the fuel cells into alternating current, which drives the vehicle's traction motor.

Diagram of a fuel cell with a proton-exchange membrane:
1 - anode;
2 - proton exchange membrane (PEM);
3 - catalyst (red);
4 - cathode

The Proton Exchange Membrane Fuel Cell (PEMFC) uses one of the simplest reactions of any fuel cell.

Separate fuel cell cell

Let's consider how the fuel cell works. The anode, the negative pole of the fuel cell, conducts electrons that are freed from hydrogen molecules so that they can be used in an external electrical circuit (circuit). For this, channels are engraved in it, distributing hydrogen evenly over the entire surface of the catalyst. The cathode (positive pole of the fuel cell) has engraved channels that distribute oxygen over the catalyst surface. It also conducts electrons back from the outer loop (circuit) to the catalyst, where they can combine with hydrogen ions and oxygen to form water. The electrolyte is a proton exchange membrane. It is a special material, similar to ordinary plastic, but with the ability to pass positively charged ions and block the passage of electrons.
A catalyst is a special material that facilitates the reaction between oxygen and hydrogen. The catalyst is usually made from platinum powder coated in a very thin layer on carbon paper or cloth. The catalyst must be rough and porous in order for its surface to be in maximum contact with hydrogen and oxygen. The platinum-coated side of the catalyst is in front of the proton exchange membrane (PEM).
Hydrogen gas (H 2) is supplied to the fuel cell under pressure from the anode side. When an H2 molecule comes into contact with platinum on the catalyst, it splits into two parts, two ions (H +) and two electrons (e–). The electrons are conducted through the anode, where they travel through the outer loop (circuit) to do useful work (such as driving an electric motor) and return from the cathode side of the fuel cell.
Meanwhile, at the cathode side of the fuel cell, oxygen gas (O 2) is forced through the catalyst where it forms two oxygen atoms. Each of these atoms has a strong negative charge that attracts two H + ions across the membrane, where they combine with an oxygen atom and two electrons from the outer circuit (chain) to form a water molecule (H 2 O).
This reaction in a single fuel cell produces approximately 0.7 watts of power. To raise the power to the required level, many individual fuel cells must be combined to form a fuel cell stack.
POM fuel cells operate at a relatively low temperature (around 80 ° C), which means that they can be quickly heated to operating temperature and do not require expensive cooling systems. Continuous improvement of the technologies and materials used in these cells have brought their power closer to the level when a battery of such fuel cells, which occupies a small part of the trunk of a car, can provide the energy needed to drive a car.
Over the past years, most of the world's leading car manufacturers have invested heavily in fuel cell vehicle designs. Many have already demonstrated fuel cell vehicles with satisfactory power and dynamic performance, although they were quite expensive.
The improvement of the designs of such vehicles is going on very intensively.

A fuel cell vehicle uses a power plant located under the floor of the vehicle

The NECAR V car is made on the basis of the Mercedes-Benz A-class car, and the entire power plant, together with the fuel cells, is located under the floor of the car. Such a constructive solution makes it possible to place four passengers and luggage in the car. Here, not hydrogen, but methanol is used as fuel for the car. Methanol is converted to hydrogen by a reformer (a device that converts methanol to hydrogen) to power the fuel cell. The use of the reformer on board the vehicle makes it possible to use almost any hydrocarbon as fuel, which makes it possible to refuel a fuel cell vehicle using the existing network of filling stations. In theory, fuel cells produce nothing but electricity and water. Converting fuel (gasoline or methanol) into hydrogen, which is required for a fuel cell, somewhat reduces the environmental attractiveness of such a car.
Honda, which has been involved in fuel cells since 1989, manufactured a small batch of Honda FCX-V4s with Ballard proton exchange membrane fuel cells in 2003. These fuel cells generate 78 kW of electrical power, while traction motors with a power of 60 kW and a torque of 272 Nm are used to drive the drive wheels. it has excellent dynamics, and the supply of compressed hydrogen makes it possible to run up to 355 km.

The Honda FСX car uses electric energy for movement, obtained by means of fuel cells.
The Honda FCX is the world's first fuel cell vehicle to receive US government certification. The vehicle is ZEV - Zero Emission Vehicle certified. Honda is not going to sell these cars yet, but is leasing about 30 cars in units. California and Tokyo, where a hydrogen refueling infrastructure already exists.

General Motors' Hy Wire concept car features fuel cell powertrain

General Motors is conducting extensive research into the development and creation of fuel cell vehicles.

Hy Wire car chassis

The GM Hy Wire concept car has received 26 patents. The basis of the car is a 150 mm thick functional platform. Inside the platform are hydrogen tanks, a fuel cell power plant and vehicle control systems using the latest electronic control technology by wire. The Hy Wire chassis is a thin platform that encloses all of the vehicle's major structural elements: hydrogen tanks, fuel cells, batteries, electric motors and control systems. This approach to design makes it possible to change car bodies during operation. The company is also testing prototype Opel fuel cell vehicles and is designing a fuel cell plant.

Liquefied Hydrogen Safe Fuel Tank Design:
1 - filling device;
2 - external tank;
3 - supports;
4 - level sensor;
5 - inner tank;
6 - filling line;
7 - insulation and vacuum;
8 - heater;
9 - mounting box

The BMW company pays much attention to the problem of using hydrogen as a fuel for automobiles. Together with Magna Steyer, a firm known for its work on the use of liquefied hydrogen in space research, BMW has developed a liquefied hydrogen fuel tank that can be used in automobiles.

Tests have confirmed the safety of using a liquid hydrogen fuel tank

The company has carried out a series of tests for the safety of the structure using standard methods and confirmed its reliability.
In 2002, the Mini Cooper Hydrogen was shown at the Frankfurt Motor Show (Germany), which uses liquefied hydrogen as fuel. The fuel tank of this vehicle occupies the same space as a regular gas tank. The hydrogen in this car is not used for fuel cells, but as fuel for the internal combustion engine.

World's first production vehicle with a fuel cell instead of a battery

In 2003, BMW announced the production of the first production vehicle with a fuel cell, the BMW 750 hL. A fuel cell battery is used instead of a traditional battery. This car has a 12-cylinder internal combustion engine that runs on hydrogen, and the fuel cell serves as an alternative to a conventional battery, allowing the air conditioner and other electrical consumers to operate when the car is parked for long periods of time with the engine inoperative.

Refueling with hydrogen is carried out by a robot, the driver is not involved in this process

The same BMW company has also developed robotic fuel dispensers, which ensure fast and safe refueling of cars with liquefied hydrogen.
A large number of developments in recent years aimed at creating cars using alternative fuels and alternative power plants indicate that the internal combustion engines, which have dominated cars over the past century, will eventually give way to cleaner, environmentally efficient and silent designs. Their wide distribution is currently constrained not by technical, but rather by economic and social problems. For their widespread use, it is necessary to create a certain infrastructure for the development of the production of alternative fuels, the creation and distribution of new filling stations and to overcome a number of psychological barriers. The use of hydrogen as a vehicle fuel will require storage, delivery and distribution issues with serious safety measures.
In theory, hydrogen is available in unlimited quantities, but its production is very energy intensive. In addition, to transfer cars to work on hydrogen fuel, it is necessary to make two major changes to the power system: first, transfer its operation from gasoline to methanol, and then, for some time, to hydrogen. It will take some time before this issue is resolved.

Horizon: Zero Dawn | 2017-03-14

Horizon: Zero Dawn has 5 fuel cells to complete the quest Ancient Arsenal for which give Shield Weaver- the best armor set in the game.

Horizon: Zero Dawn Fuel Cell Locations

You will find the first battery early in the game. You have to go to Ruin that Eloy remembers from childhood. On the map, this point is marked with a green marker, and you need to keep your way to it. You can enter the ruins through a small hole in the ground. Your task is to go down to the first level.

Getting lost in the ruins is almost impossible, but be extremely careful. Sometimes you have to go down the stairs, find doors and break stalactites.

The fuel cell is on the table and has a green icon.

The second item can be found after passing the mission "Heart of Nora"... Early on, you will find a door with a switch, use it, unlock the door and continue on your way. Turn right, and then follow to the door that is in front.

After that, you will find a holo-lock, which you will not be able to open. To the left of it you can see a hole with candles inside. Move in this direction and soon you will find an element lying on the ground.

The third element can be found during the mission. "Master's Reach"... One of the mission tasks will be to climb a tall building. And once on top of it, you will receive a new assignment - to find information in the office of Faro.

When you reach the right place, do not follow ahead. Turn around and climb the wall in front. After finding a fuel cell, you can put it in your inventory and continue the task.

Fourth fuel cell

The fourth element can be found in the process of completing the mission "Treasure of Death"... After you solve the holo-locks problem, go to the third floor, follow the stairs and soon you will find the right place. On the left in the corridor there will be a door with a holo-lock. Inside this room is the fuel cell.

The fifth element can be found in the course of the mission "Fallen Mountain"... At some point, you will find yourself in a huge cave, after which you should not go down to the very bottom. Turn around and you will see a rock in front of you that you need to climb. At the top you will see a tunnel with a purple glow, go into it and follow to the very end. A food unit will be waiting for you on the shelf.

Very soon (more precisely, at the beginning of her exciting adventure), the main character will stumble upon the Forerunner bunker, which is located very close to the lands of the Nora tribe. Inside this ancient bunker, behind a powerful and high-tech door, armor will be closed, from a distance looking not only dignified, but also very attractive. The armor is called the "Shieldweaver" and is actually the best piece of equipment in the game. Therefore, a bunch of questions immediately arise: "How to find and get the Shield Weaver armor?", "Where to find fuel?", "How to open the bunker doors?" and many other questions related to the same topic. So, in order to open the doors of the bunker and get the coveted armor, you need to find five fuel cells, which in turn will be scattered throughout the game world. Below I will tell you about where and how to find fuel cells to solve puzzles during searches and in the Ancient Arsenal.

: The presented guide has not only a detailed text walkthrough, but also screenshots are attached to each fuel cell, and at the end there is a video. All this was created in order to facilitate your searches, so if some point in the text passage is not clear, then I recommend watching screenshots and a video.

... The first fuel - "Mother's Heart"

Where and How to Find the First Fuel Cell - Fuel Location.

So, Eloy will be able to find the very first fuel cell (or, more simply, fuel) long before entering the open world on the mission "Mother's Womb". The bottom line is that after the task "Initiation" (which, by the way, also refers to the storyline), the main character will find herself in a place called "Mother's Heart", which is a sacred place of the Nora tribe and the abode of the Matriarchs.

As soon as the girl gets out of bed, successively go through several rooms (rooms), where in one of them you will stumble upon a sealed door, which you simply cannot open. At this moment, I strongly recommend that you look around, because next to the heroine (or near the doors - as it is more convenient) there is a ventilation shaft, moreover, decorated with burning candles (in general, you need it here).

After you pass a certain segment of the path along the ventilation shaft, the heroine will find herself behind a locked door. Look at the floor next to the wall block and mysterious candles - this is where the first fuel cell lies.

: Be sure to remember that if you do not pick up the first fuel cell before entering the open world, then after that you will only get to this location at the later stages of the passage. But to be more precise, after completing the "Heart of the Burrow" quest, so I recommend picking up the fuel now.

... Second fuel - "Ruins"

Where and How to Find the Second Fuel Cell - Fuel Location.

The first thing you need to know when looking for a second fuel: the main character was already in this location, when a long time ago she fell into ruins as a child (at the very beginning of the game). So after completing the "Initiation" task, you will have to remember your deep childhood and go down to this place one more time to get the second fuel cell.

Below are some pictures (screenshots). The first picture shows the entrance to the ruins (in red). Inside the ruins, you will need to get to the first level - this is the lower right area, which will be highlighted in purple on the map. In addition, there will also be a door that the girl can open with her spear.

As soon as Aloy passes through the doors, climb the stairs higher and, as soon as possible, turn to the right side: in her deep youth, Aloy could not crawl through stalactites, but now she has useful "toys" that will cope with any task. So, take out the spear and break the stalactites with it. Soon the path will be clear, so it remains to take the fuel cell that is on the table and go for the next one. If some moment of the passage is not clear, then screenshots are attached below in order.

... Third fuel - "Master's Reach"

Where and How to Find the Third Fuel Cell - Fuel Location.

It's time to head north. During the passage of the quest "The Reach of the Master" Aloy will have to carefully explore and study the giant ruins of the Forerunners. So in these ruins on the twelfth level the next, third fuel cell will be hidden.

Therefore, you will have to climb not only to the upper level of these ruins, but also there to climb even a little higher. Don't waste precious time and climb higher along the surviving part of the building. Climb up until you find yourself on a small area open to all winds. Then everything is simple, because the third element of fuel will lie at the top: no puzzles, no riddles and secrets. So take your fuel, get down and move on.

... Fourth fuel - "Treasure of Death"

Where and How to Find the Fourth Fuel Cell - Fuel Location.

The good news is that this fuel cell is also located in the northern part of Horizon: Zero Dawn, but slightly closer to the Nora tribe. The main character will again get to this part of the map during the passage of the next storyline task. But before getting to the penultimate fuel cell, Eloy will need to restore the power supply of the sealed door, which is located on the third level of the location. Moreover, this will require solving a small and not too difficult puzzle. The puzzle is connected with blocks and regulators (there are two blocks of four regulators on the level below the doors). So, to begin with, I recommend that you deal with the left block of regulators: the first regulator should be raised (looking) up, the second - to the right, the third - to the left, the fourth - down.

After that, go to the block on the right side. Do not touch the first two knobs, but the third and fourth knobs should be turned down. Therefore, go up one level - here is the last block of regulators. The correct order would look like this: 1 - up, 2 - down, 3 - left, 4 - right.

Once you get it right, the knobs will change from white to turquoise. Thus, the power supply will be restored. So go back up to the door and open it. Behind the doors the heroine will be "greeted" by the penultimate fuel cell, so it will be possible to go for the next, last fuel.

... Fifth fuel - "GAYA Prime"

Where and How to Find the 5th Fuel Cell - Fuel Location.

Finally, the last fuel cell. And again you can get it only during the passage of the storyline. This time the main character will have to go to the ruins called "GAYA Prime". At this point, you need to pay special attention when you find yourself near the third level. The bottom line is that at a certain moment, the girl will face an attractive abyss, into which it will be possible to descend by rope, although one should not go there.

Before the abyss, you should turn to the left and first investigate the hidden cave: it will be possible to get into it if you carefully go down the slope of the mountain. Go inside and then move forward until the very end. In the last room in the room on the right side there will be a rack on which the last fuel cell is finally located. Together with him, you can now safely return back to the bunker and open all the locks in order to get gorgeous equipment.

... How to get into the Ancient Arsenal?

Well, now it remains to return to the Ancient Arsenal to receive the long-awaited reward. If you don't remember the corridors of the arsenal, then check out the screenshots below, which will help you remember the whole journey.

When you get to the right place and start down, insert the fuel cells into the empty cells. As a result, the regulators will light up, so you have to solve a new puzzle to open the doors. So, the first regulator should be directed up, the second - to the right, the third - down, the fourth - to the left, the fifth - up. As soon as you do everything right, the doors will open, but this is far from the end.

Next, you have to unlock the lock (or mounts) of the armor - this is another simple puzzle related to the regulators, in which you will have to use the remaining fuel cells. The first knob should be turned - to the right, the second - to the left, the third - up, the fourth - to the right, the fifth - again to the left.

Finally, after all these long torments, it will be possible to take the armor. The Shield Weaver is a very good piece of equipment that makes the main character practically invulnerable for a while. The most important thing is to constantly monitor the color of the armor: if the armor shimmers white, then everything is in order. If it is red, the shield is gone.

They are powered by US National Aeronautics and Space Administration (NASA) spacecraft. They provide electricity to the computers of the First National Bank in Omaha. They are used on some public city buses in Chicago.

These are all fuel cells. Fuel cells are electrochemical devices that generate electricity without burning — chemically, much like batteries. The only difference is that they use other chemicals, hydrogen and oxygen, and the product of a chemical reaction is water. Natural gas can also be used, however, when using hydrocarbon fuels, of course, a certain level of carbon dioxide emissions is inevitable.

Because fuel cells can operate efficiently and without harmful emissions, they hold great promise for a sustainable energy source that will help reduce emissions of greenhouse gases and other pollutants. The main obstacle to the widespread use of fuel cells is their high cost compared to other devices that generate electricity or propel vehicles.

History of development

The first fuel cells were demonstrated by Sir William Groves in 1839. Groves showed that the electrolysis process — the splitting of water into hydrogen and oxygen by an electric current — is reversible. That is, hydrogen and oxygen can be chemically combined to form electricity.

After this was demonstrated, many scientists rushed to study fuel cells with zeal, but the invention of the internal combustion engine and the development of infrastructure for the extraction of oil reserves in the second half of the nineteenth century left the development of fuel cells far behind. The development of fuel cells was further constrained by their high cost.

The burst of fuel cell development came in the 1950s, when NASA turned to them in connection with the emerging need for a compact power generator for space flights... Appropriate funds were invested, and as a result, Apollo and Gemini flights were carried out on fuel cells. Spacecraft are also powered by fuel cells.

Fuel cells are still largely an experimental technology, but several companies already sell them on the commercial market. In the last nearly ten years alone, there have been significant advances in commercial fuel cell technology.

How does a fuel cell work

Fuel cells are like storage batteries - they generate electricity through a chemical reaction. In contrast, internal combustion engines burn fuel and thus generate heat, which is then converted into mechanical energy. Unless the heat from the exhaust gases is used in some way (for example, for heating or air conditioning), then the efficiency of the internal combustion engine can be said to be quite low. For example, the efficiency of fuel cells in a vehicle - a project currently under development - is expected to be more than double the efficiency of today's typical gasoline engines used in automobiles.

While batteries and fuel cells both generate electricity chemically, they serve two completely different functions. Batteries are stored energy devices: the electricity they generate is the result of a chemical reaction from a substance already inside them. Fuel cells do not store energy, but convert some of the energy from externally supplied fuel into electricity. In this respect, a fuel cell is more like a conventional power plant.

There are several different types of fuel cells. The simplest fuel cell consists of a special membrane known as an electrolyte. Powdered electrodes are applied on both sides of the membrane. This design - an electrolyte surrounded by two electrodes - is a separate element. Hydrogen flows to one side (anode) and oxygen (air) to the other (cathode). Different chemical reactions take place at each electrode.

At the anode, hydrogen decays into a mixture of protons and electrons. In some fuel cells, the electrodes are surrounded by a catalyst, usually made of platinum or other noble metals, which facilitate the dissociation reaction:

2H2 ==> 4H + + 4e-.

H2 = diatomic hydrogen molecule, form, in

which hydrogen is present in the form of a gas;

H + = ionized hydrogen, i.e. proton;

e- = electron.

The operation of a fuel cell is based on the fact that the electrolyte passes protons through itself (towards the cathode), but electrons do not. Electrons move to the cathode along an external conducting circuit. This movement of electrons is an electrical current that can be used to drive an external device connected to a fuel cell, such as an electric motor or a light bulb. This device is commonly referred to as a "load".

On the cathode side of the fuel cell, protons (which have passed through the electrolyte) and electrons (which have passed through an external load) "reunite" and react with the oxygen supplied to the cathode to form water, H2O:

4H + + 4e- + O2 ==> 2H2O.

The overall response in a fuel cell is written as follows:

2H2 + O2 ==> 2H2O.

In their work, fuel cells use hydrogen fuel and oxygen from the air. The hydrogen can be supplied directly or by extraction from an external fuel source such as natural gas, gasoline, or methanol. In the case of an external source, it must be chemically transformed to extract hydrogen. This process is called "reforming". Hydrogen can also be obtained from ammonia, alternative resources such as gas from city landfills and wastewater treatment plants, and water electrolysis, which uses electricity to decompose water into hydrogen and oxygen. Currently, most fuel cell technologies used in transport use methanol.

Various means have been developed for reforming fuel to produce hydrogen for fuel cells. The US Department of Energy has developed a fuel system inside a gasoline reformer to supply hydrogen to a self-contained fuel cell. Researchers at the Pacific Northwest National Laboratory in the United States have demonstrated a compact reformer fuel plant one-tenth the size of a power supply unit. A US utility company, Northwest Power Systems, and Sandia National Laboratory have demonstrated a fuel reformer that converts diesel fuel to hydrogen for fuel cells.

Individually, the fuel cells produce about 0.7-1.0 volts each. To increase the voltage, the elements are assembled in a "cascade", ie. serial connection. To create more current, sets of cascading elements are connected in parallel. If you combine the cascades of fuel cells with a fuel system, an air and cooling system, and a control system, you get a fuel cell engine. This engine can drive a vehicle, a stationary power plant, or a portable electric generator6. Fuel cell engines come in different sizes depending on the application, the type of fuel cell and the fuel used. For example, the size of each of the four separate 200 kW stationary power plants installed at a bank in Omaha is roughly the size of a truck trailer.

Applications

Fuel cells can be used in both stationary and mobile devices. In response to tougher U.S. emissions regulations, car manufacturers including DaimlerChrysler, Toyota, Ford, General Motors, Volkswagen, Honda and Nissan have experimented and demonstrated fuel cell vehicles. The first commercial fuel cell vehicles are expected to hit the road in 2004 or 2005.

A major milestone in the history of fuel cell technology was the demonstration in June 1993 of the Ballard Power System's experimental 32-foot city bus powered by a 90 kilowatt hydrogen fuel cell engine. Since then, many different types and different generations of fuel cell passenger vehicles have been developed and commissioned. Since late 1996, three hydrogen fuel cell golf carts have been in use at Palm Desert, California. On the roads of Chicago, Illinois; Vancouver, British Columbia; and Oslo, Norway is testing fuel cell city buses. Alkaline fuel cell taxis are being tested on the streets of London.

Stationary installations using fuel cell technology are also being demonstrated, but they are not yet widely used commercially. The First National Bank of Omaha in Nebraska uses a fuel cell system to power computers, as the system is more reliable than the old system, which was powered by a battery backed mains supply. The world's largest commercial fuel cell system, with a capacity of 1.2 MW, will soon be installed at a postal processing center in Alaska. Fuel cell laptop computers, wastewater treatment plant control systems and vending machines are also being tested and demonstrated.

"Pros and cons"

Fuel cells have several advantages. While the efficiency of modern internal combustion engines is only 12-15%, the efficiency of fuel cells is 50%. The efficiency of fuel cells can remain at a fairly high level even when they are not used at their full rated power, which is a significant advantage over gasoline engines.

The modular design of fuel cells means that the capacity of a fuel cell power plant can be increased simply by adding a few more stages. This minimizes the capacity underutilization factor, which allows for a better match between supply and demand. Since the efficiency of a fuel cell stack is determined by the performance of the individual cells, small fuel cell power plants operate as efficiently as large ones. In addition, waste heat from stationary fuel cell systems can be used to heat water and rooms, further increasing energy efficiency.

When using fuel cells, there are practically no harmful emissions. When the engine runs on pure hydrogen, only heat and pure water vapor are generated as byproducts. So on spaceships, astronauts drink water, which is formed as a result of the operation of onboard fuel cells. The composition of the emissions depends on the nature of the hydrogen source. Using methanol produces zero nitrogen oxides and carbon monoxide emissions and only small hydrocarbon emissions. Emissions increase with the transition from hydrogen to methanol and gasoline, although even with gasoline, emissions will remain fairly low. In any case, replacing today's traditional internal combustion engines with fuel cells would result in an overall reduction in CO2 and nitrogen oxide emissions.

The use of fuel cells provides flexibility to the energy infrastructure, creating additional opportunities for decentralized power generation. The plurality of decentralized energy sources allows to reduce losses during transmission of electricity and develop energy markets (which is especially important for remote and rural areas, in the absence of access to power lines). With the help of fuel cells, individual residents or neighborhoods can provide themselves with most of the electricity and thus significantly increase the efficiency of its use.

Fuel cells offer energy of high quality and increased reliability. They are durable, they have no moving parts, and they produce a constant amount of energy.

However, fuel cell technology needs further improvement in order to improve their performance, reduce costs, and thus make fuel cells competitive with other energy technologies. It should be noted that when considering the cost characteristics of energy technologies, comparisons should be made on the basis of all the constituent technological characteristics, including capital operating costs, pollutant emissions, energy quality, durability, decommissioning and flexibility.

Although hydrogen gas is the best fuel, the infrastructure or transportation base for it does not yet exist. In the short term, existing fossil fuel supply systems (gas stations, etc.) could be used to provide power plants with hydrogen sources in the form of gasoline, methanol or natural gas. This would eliminate the need for dedicated hydrogen filling stations, but would require that a fossil-to-hydrogen converter ("reformer") be installed on each vehicle. The disadvantage of this approach is that it uses fossil fuels and thus results in carbon dioxide emissions. Methanol, currently the leading candidate, generates fewer emissions than gasoline, but it would require a larger capacity on the car as it takes up twice the space for the same energy content.

Unlike fossil fuel supply systems, solar and wind systems (using electricity to create hydrogen and oxygen from water) and direct photoconversion systems (using semiconductor materials or enzymes to produce hydrogen) could supply hydrogen without a reforming step, and so Thus, emissions of harmful substances could be avoided, which is observed when using methanol or gasoline fuel cells. The hydrogen could be stored and converted to electricity in the fuel cell as needed. Going forward, combining fuel cells with this kind of renewable energy is likely to be an effective strategy for providing a productive, environmentally sound and versatile energy source.

IEER's recommendation is that local, federal, and state governments allocate a portion of their transportation procurement budgets to fuel cell vehicles as well as fixed fuel cell systems to provide heat and electricity for some of their significant or new buildings. This will help develop vital technology and reduce greenhouse gas emissions.

Similar to the existence of different types of internal combustion engines, there are different types of fuel cells - the choice of the appropriate type of fuel cell depends on the application.

Fuel cells are divided into high temperature and low temperature. Low temperature fuel cells require relatively pure hydrogen as fuel. This often means that fuel processing is required to convert the primary fuel (such as natural gas) to pure hydrogen. This process consumes additional energy and requires special equipment. High temperature fuel cells do not need this additional procedure, as they can carry out an "internal conversion" of the fuel at elevated temperatures, which means there is no need to invest in a hydrogen infrastructure.

Fuel cells based on molten carbonate (RKTE)

Molten carbonate electrolyte fuel cells are high temperature fuel cells. The high operating temperature allows natural gas to be used directly without a processor fuel and low calorific value fuel gas for industrial processes and other sources. This process was developed in the mid-1960s. Since then, production technology, performance and reliability have been improved.

The operation of RKTE is different from other fuel cells. These cells use an electrolyte from a mixture of molten carbonate salts. Currently, there are two types of mixtures in use: lithium carbonate and potassium carbonate or lithium carbonate and sodium carbonate. To melt carbonate salts and achieve a high degree of ion mobility in the electrolyte, fuel cells with molten carbonate electrolyte operate at high temperatures (650 ° C). The efficiency varies between 60-80%.

When heated to 650 ° C, salts become a conductor for carbonate ions (CO 3 2-). These ions pass from the cathode to the anode, where they combine with hydrogen to form water, carbon dioxide and free electrons. These electrons are channeled back to the cathode through an external electrical circuit, generating electrical current and heat as a by-product.

Reaction at the anode: CO 3 2- + H 2 => H 2 O + CO 2 + 2e -
Reaction at the cathode: CO 2 + 1/2 O 2 + 2e - => CO 3 2-
General reaction of the element: H 2 (g) + 1/2 O 2 (g) + CO 2 (cathode) => H 2 O (g) + CO 2 (anode)

The high operating temperatures of molten carbonate electrolyte fuel cells have certain advantages. At high temperatures, natural gas is internally reformed, eliminating the need for a fuel processor. In addition, the benefits include the ability to use standard materials of construction such as stainless steel sheet and a nickel catalyst on the electrodes. The waste heat can be used to generate high pressure steam for a variety of industrial and commercial purposes.

High reaction temperatures in the electrolyte also have their advantages. The use of high temperatures takes a long time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. These characteristics allow the use of fuel cell installations with molten carbonate electrolyte under constant power conditions. High temperatures prevent carbon monoxide damage to the fuel cell, "poisoning", etc.

Molten carbonate electrolyte fuel cells are suitable for use in large stationary installations. Thermal power plants with an output electric power of 2.8 MW are industrially produced. Installations with an output power of up to 100 MW are being developed.

Phosphoric acid fuel cells (FCTE)

Phosphoric (orthophosphoric) acid fuel cells were the first fuel cells for commercial use. This process was developed in the mid-1960s and has been tested since the 1970s. Since then, stability has been increased, performance has been reduced, and cost has been reduced.

Fuel cells based on phosphoric (orthophosphoric) acid use an electrolyte based on phosphoric acid (H 3 PO 4) with a concentration of up to 100%. The ionic conductivity of phosphoric acid is low at low temperatures, which is why these fuel cells are used at temperatures up to 150–220 ° C.

The charge carrier in this type of fuel cell is hydrogen (H +, proton). A similar process occurs in fuel cells with a proton exchange membrane (MOPTE), in which the hydrogen supplied to the anode is separated into protons and electrons. Protons travel through the electrolyte and combine with oxygen from the air at the cathode to form water. Electrons are channeled through an external electrical circuit, generating an electrical current. Below are the reactions that generate electricity and heat.

Reaction at the anode: 2H 2 => 4H + + 4e -
Reaction at the cathode: O 2 (g) + 4H + + 4e - => 2H 2 O
General reaction of the element: 2H 2 + O 2 => 2H 2 O

The efficiency of fuel cells based on phosphoric (orthophosphoric) acid is more than 40% when generating electrical energy. With combined heat and power generation, the overall efficiency is around 85%. In addition, given the operating temperatures, the waste heat can be used to heat water and generate steam at atmospheric pressure.

The high performance of thermal power plants on fuel cells based on phosphoric (orthophosphoric) acid in the combined production of heat and electricity is one of the advantages of this type of fuel cells. The plants use carbon monoxide with a concentration of about 1.5%, which significantly expands the choice of fuel. In addition, CO 2 does not affect the electrolyte and the operation of the fuel cell; this type of cell works with reformed natural fuel. Simple design, low electrolyte volatility and increased stability are also advantages of this type of fuel cell.

Thermal power plants with an output electric power of up to 400 kW are industrially produced. The 11 MW units have been tested accordingly. Installations with an output power of up to 100 MW are being developed.

Membrane proton exchange fuel cells (MOPTE)

Membrane fuel cells are considered the best type of fuel cell for generating vehicle power, which can replace gasoline and diesel internal combustion engines. These fuel cells were first used by NASA for the Gemini program. Today, MOPTE units with a capacity from 1W to 2 kW are being developed and demonstrated.

These fuel cells use a solid polymer membrane (thin plastic film) as the electrolyte. When impregnated with water, this polymer allows protons to pass through but does not conduct electrons.

The fuel is hydrogen, and the charge carrier is a hydrogen ion (proton). At the anode, a hydrogen molecule is split into a hydrogen ion (proton) and electrons. Hydrogen ions pass through the electrolyte to the cathode, while electrons move around the outer circle and produce electrical energy. Oxygen, which is taken from the air, is fed to the cathode and combines with electrons and hydrogen ions to form water. The following reactions occur on the electrodes:

Reaction at the anode: 2H 2 + 4OH - => 4H 2 O + 4e -
Reaction at the cathode: O 2 + 2H 2 O + 4e - => 4OH -
General reaction of the element: 2H 2 + O 2 => 2H 2 O

Compared to other types of fuel cells, proton exchange membrane fuel cells produce more energy for a given volume or weight of the fuel cell. This feature allows them to be compact and lightweight. In addition, the operating temperature is less than 100 ° C, which allows for quick start-up of operation. These characteristics, as well as the ability to quickly change energy output, are just some of the features that make these fuel cells a prime candidate for vehicle use.

Another advantage is that the electrolyte is a solid, not a liquid, substance. Keeping gases at the cathode and anode is easier with a solid electrolyte, and therefore such fuel cells are cheaper to manufacture. Compared with other electrolytes, when using a solid electrolyte, there are no such difficulties as orientation, there are fewer problems due to the occurrence of corrosion, which leads to a longer life of the cell and its components.

Solid oxide fuel cells (SOFC)

Solid oxide fuel cells are the fuel cells with the highest operating temperature. The operating temperature can be varied from 600 ° C to 1000 ° C, which allows different types of fuel to be used without special pre-treatment. To handle such high temperatures, the electrolyte used is a thin, ceramic-based, solid metal oxide, often an alloy of yttrium and zirconium, which is a conductor of oxygen ions (O 2 -). The technology of using solid oxide fuel cells has been developing since the late 1950s. and has two configurations: planar and tubular.

Solid electrolyte provides a hermetically sealed transition of gas from one electrode to another, while liquid electrolytes are located in a porous substrate. The charge carrier in this type of fuel cell is an oxygen ion (O 2 -). At the cathode, oxygen molecules from the air are separated into an oxygen ion and four electrons. Oxygen ions pass through the electrolyte and combine with hydrogen to form four free electrons. Electrons are channeled through an external electrical circuit, generating electrical current and waste heat.

Reaction at the anode: 2H 2 + 2O 2 - => 2H 2 O + 4e -
Reaction at the cathode: O 2 + 4e - => 2O 2 -
General reaction of the element: 2H 2 + O 2 => 2H 2 O

The efficiency of the generated electrical energy is the highest of all fuel cells - about 60%. In addition, the high operating temperatures enable combined heat and power generation to generate high pressure steam. Combining a high-temperature fuel cell with a turbine makes it possible to create a hybrid fuel cell to increase the efficiency of electric power generation by up to 70%.

Solid oxide fuel cells operate at very high temperatures (600 ° C – 1000 ° C), which takes a long time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. At such high operating temperatures, a converter is not required to recover hydrogen from the fuel, which allows the thermal power plant to operate with relatively unclean fuels resulting from the gasification of coal or waste gases and the like. Also, this fuel cell is excellent for high power operation, including industrial and large central power plants. Modules with an output electrical power of 100 kW are commercially produced.

Direct Methanol Oxidation Fuel Cells (POMTE)

The technology of using fuel cells with direct methanol oxidation is undergoing a period of active development. It has successfully established itself in the field of powering mobile phones, laptops, as well as for creating portable power sources. what the future use of these elements is aimed at.

The design of fuel cells with direct methanol oxidation is similar to fuel cells with a proton exchange membrane (MOPTE), i.e. a polymer is used as an electrolyte, and a hydrogen ion (proton) is used as a charge carrier. However, liquid methanol (CH 3 OH) is oxidized in the presence of water at the anode with the release of CO 2, hydrogen ions and electrons, which are channeled through an external electrical circuit, thereby generating an electric current. Hydrogen ions pass through the electrolyte and reacts with oxygen from the air and electrons from the external circuit to form water at the anode.

Reaction at the anode: CH 3 OH + H 2 O => CO 2 + 6H + + 6e -
Reaction at the cathode: 3/2 O 2 + 6H + + 6e - => 3H 2 O
General reaction of the element: CH 3 OH + 3/2 O 2 => CO 2 + 2H 2 O

The development of these fuel cells began in the early 1990s. With the development of improved catalysts and other recent innovations, power density and efficiency have been increased to 40%.

These elements were tested in a temperature range of 50-120 ° C. With their low operating temperatures and no need for a converter, direct methanol fuel cells are the best candidate for applications in mobile phones and other consumer goods as well as in automobile engines. The advantage of this type of fuel cell is its small size, due to the use of liquid fuel, and the absence of the need for a converter.

Alkaline fuel cells (SHFC)

Alkaline fuel cells (ALFCs) are one of the most studied technologies, used since the mid-1960s. by NASA in the Apollo and Space Shuttle programs. Aboard these spaceships, fuel cells produce electricity and drinking water. Alkaline fuel cells are one of the most efficient elements used to generate electricity, with power generation efficiency reaching up to 70%.

Alkaline fuel cells use an electrolyte, that is, an aqueous solution of potassium hydroxide contained in a porous stabilized matrix. The concentration of potassium hydroxide can vary depending on the operating temperature of the fuel cell, which ranges from 65 ° C to 220 ° C. The charge carrier in SHFC is a hydroxyl ion (OH -), which moves from the cathode to the anode, where it reacts with hydrogen, producing water and electrons. The water produced at the anode moves back to the cathode, again generating hydroxyl ions there. This series of reactions in the fuel cell produces electricity and, as a by-product, heat:

Reaction at the anode: 2H 2 + 4OH - => 4H 2 O + 4e -
Reaction at the cathode: O 2 + 2H 2 O + 4e - => 4OH -
General reaction of the system: 2H 2 + O 2 => 2H 2 O

The advantage of SHFCs is that these fuel cells are the cheapest to manufacture, since the catalyst that is needed on the electrodes can be any of the substances that are cheaper than those used as catalysts for other fuel cells. In addition, SCFCs operate at a relatively low temperature and are one of the most efficient fuel cells - such characteristics can accordingly contribute to the acceleration of power generation and high fuel efficiency.

One of the characteristic features of SHFC is its high sensitivity to CO 2, which can be contained in fuel or air. CO 2 reacts with the electrolyte, quickly poisons it, and greatly reduces the efficiency of the fuel cell. Therefore, the use of SHTE is limited to closed spaces, such as space and underwater vehicles, they must operate on pure hydrogen and oxygen. Moreover, molecules such as CO, H 2 O and CH 4, which are safe for other fuel cells, and even fuel for some of them, are harmful to SHFCs.

Polymer electrolyte fuel cells (PETE)

In the case of polymer electrolyte fuel cells, the polymer membrane consists of polymer fibers with water regions in which the conductivity of water ions H 2 O + (proton, red) is attached to the water molecule. Water molecules pose a problem due to their slow ion exchange. Therefore, a high concentration of water is required both in the fuel and at the outlet electrodes, which limits the operating temperature to 100 ° C.

Solid Acid Fuel Cells (TKTE)

In solid acid fuel cells, the electrolyte (C s HSO 4) does not contain water. The operating temperature is therefore 100-300 ° C. The rotation of the oxy anions SO 4 2- allows the protons (red) to move as shown in the figure. Typically, a solid acid fuel cell is a sandwich in which a very thin layer of a solid acid compound is sandwiched between two tightly compressed electrodes to ensure good contact. When heated, the organic component evaporates, leaving through the pores in the electrodes, retaining the ability of multiple contacts between the fuel (or oxygen at the other end of the cells), electrolyte and electrodes.

Fuel cell type	Working temperature	Power generation efficiency	Fuel type	Application area
RKTE	550-700 ° C	50-70%		Medium and large installations
FKTE	100-220 ° C	35-40%	Pure hydrogen	Large installations
MOPTE	30-100 ° C	35-50%	Pure hydrogen	Small installations
SOFC	450-1000 ° C	45-70%	Most hydrocarbon fuels	Small, medium and large installations
POMTE	20-90 ° C	20-30%	Methanol	Portable installations
SHTE	50-200 ° C	40-65%	Pure hydrogen	Space exploration
PETE	30-100 ° C	35-50%	Pure hydrogen	Small installations

Description:

This article discusses in more detail their structure, classification, advantages and disadvantages, scope, efficiency, history of creation and modern prospects of use.

Using fuel cells to power buildings

Part 1

This article discusses in more detail the principle of operation of fuel cells, their structure, classification, advantages and disadvantages, scope, efficiency, history of creation and modern prospects of use. In the second part of the article, which will be published in the next issue of the journal "AVOK", provides examples of facilities where different types of fuel cells were used as sources of heat and power supply (or only power supply).

Water can be stored even in both directions in both compressed and liquefied form, but this is also slush, both of which are caused by significant technical problems. This is due to high pressures and extremely low temperatures due to liquefaction. For this reason, for example, a stand for a water fuel dispenser must be designed differently than we are used to, the end of the filling line connects the robotic arm to the valve on the car. Connecting and filling is quite dangerous, and therefore it is best if it happens without a human presence.

Introduction

Fuel cells are highly efficient, reliable, durable and environmentally friendly. clean way getting energy.

Initially used only in the space industry, fuel cells are now increasingly used in a wide variety of areas - as stationary power plants, heat and power supply of buildings, vehicle engines, power supplies for laptops and mobile phones. Some of these devices are laboratory prototypes, some are undergoing pre-production tests or are used for demonstration purposes, but many models are mass-produced and used in commercial projects.

Such a device is in a test run at the airport in Munich, try driving here with individual cars and buses. A high kilogram of mileage is cool, but in practice it is just as important as how many kilograms it will cost and how much space a strong, thermally insulated fuel tank will take in the car. Some other water problems: - create a complex air bath - problem with garages, auto repair shops, etc. - thanks to a small molecule that penetrates into every bottleneck, screws and valves - compression and liquefaction requires significant energy consumption.

A fuel cell (electrochemical generator) is a device that converts the chemical energy of a fuel (hydrogen) into electrical energy in the process of an electrochemical reaction directly, unlike traditional technologies that use the combustion of solid, liquid and gaseous fuels. Direct electrochemical conversion of fuel is very efficient and attractive from an environmental point of view, since a minimum amount of pollutants is emitted during operation, and there are no strong noises and vibrations.

Specific pressures, compression and a set of necessary safety measures have very good value in the assessment at the end of the water, compared to liquid hydrocarbon fuels, which are produced using lightweight containers without pressure. Therefore, perhaps very urgent circumstances can contribute to his truly flattering enjoyment.

In the near future, car manufacturers are still looking for cheaper and relatively less hazardous liquid fuels. The hot melt can be methanol, which can be extracted relatively easily. Its main and only problem is toxicity, on the other hand, like water, methane can be used both in internal combustion engines and in a certain type of fuel chain. It also has some advantages in internal combustion engines, including in terms of emissions.

From a practical point of view, a fuel cell resembles a conventional galvanic battery. The difference lies in the fact that the battery is initially charged, that is, it is filled with "fuel". During operation, "fuel" is consumed and the battery is discharged. Unlike a battery, a fuel cell uses fuel supplied from an external source to generate electrical energy (Fig. 1).

In this respect, water can rise to a relatively unexpected and yet capable competition. A fuel cell is a source of current generated by an electrochemical reaction. Unlike all of our known batteries, reagents are fed into it and waste is constantly discharged, so, unlike a battery, it is virtually inexhaustible. While there are many different types, the following diagram of a hydrogen fuel cell helps us understand how it works.

Fuel is supplied to the positive electrode where it is oxidized. O2-oxygen enters the negative electrode and can be reduced.

It was even possible to develop a fuel cell that burns coal directly. Since the work of scientists from the Lawrence Livermore Laboratory, which was able to test a fuel cell that directly converts coal into electricity, could be a very important milestone in the development of energy, we will dwell on a few words. Coal soil up to 1 micron in size is mixed at 750-850 ° C with molten lithium, sodium or potassium carbonate.

For the production of electrical energy, not only pure hydrogen can be used, but also other hydrogen-containing raw materials, for example, natural gas, ammonia, methanol or gasoline. Ordinary air is used as a source of oxygen, which is also required for the reaction.

When pure hydrogen is used as a fuel, the reaction products, in addition to electrical energy, are heat and water (or water vapor), i.e., gases that cause air pollution or cause a greenhouse effect are not released into the atmosphere. If a hydrogen-containing feedstock is used as a fuel, for example, natural gas, other gases, for example, carbon and nitrogen oxides, will also be a by-product of the reaction, however, its amount is much lower than when burning the same amount of natural gas.

Then everything is done in the standard way in accordance with the above scheme: the oxygen in the air reacts with carbon to carbon dioxide, and energy is released in the form of electricity. Although we know several different types of fuel cells, they all work according to the principle described. This is a kind of controlled burning. When we mix hydrogen with oxygen, we get an explosive mixture that explodes to form water. Energy is released as heat. The hydrogen fuel cell has the same reaction, the product is also water, but the energy is released as electricity.

The process of chemically converting fuel to produce hydrogen is called reforming, and the corresponding device is called a reformer.

Advantages and disadvantages of fuel cells

Fuel cells are more energy efficient than internal combustion engines because there is no thermodynamic limitation on the energy efficiency for fuel cells. The efficiency of fuel cells is 50%, while the efficiency of internal combustion engines is 12-15%, and the efficiency of steam turbine power plants does not exceed 40%. By using heat and water, the efficiency of fuel cells is further increased.

The big advantage of a fuel cell is that it generates electricity from the fuel in one way or another directly, without an intermediate thermal installation, so the emissions are lower and the efficiency is higher. It reaches 70%, while as standard we achieve 40% conversion of coal to electricity. Why aren't we building giant fuel cells instead of power plants? The fuel cell is a rather complex device that operates at high temperatures, so the requirements for electrode materials and the electrolyte itself are high.

Unlike, for example, internal combustion engines, the efficiency of fuel cells remains very high even when they are not operating at full power. In addition, the power of the fuel cells can be increased by simply adding individual blocks without changing the efficiency, i.e. large installations are as efficient as small ones. These circumstances allow a very flexible selection of the composition of the equipment in accordance with the wishes of the customer and ultimately lead to a reduction in equipment costs.

Electrolytes include, for example, ion exchange membranes or conductive ceramic materials, or rather expensive materials, or phosphoric acid, sodium hydroxide or molten alkali metal carbonates, which are very corrosive to tissue alteration. It was precisely this difficulty that, after the initial enthusiasm in the twentieth century, fuel cells, apart from the space program, were not more significant.

Interest then diminished again when it was revealed that wider use was above the technology's capabilities at the time. However, over the past thirty years, development has not stopped, new materials and concepts have emerged, and our priorities have changed - we now pay much more attention to environmental protection than we did then. Therefore, we are experiencing some renaissance of fuel cells, which are increasingly being used in many areas. There are 200 such devices around the world. For example, they serve as a backup device where network failure can cause serious problems - for example, in hospitals or military institutions.

An important advantage of fuel cells is their environmental friendliness. The airborne emissions of fuel cells are so low that in some areas of the United States, they do not require special approval from government air quality control agencies to operate them.

Fuel cells can be placed directly in the building, thereby reducing energy transport losses, and the heat generated by the reaction can be used to supply heating or hot water to the building. Autonomous sources of heat and power supply can be very beneficial in remote areas and in regions that are characterized by a shortage of electricity and its high cost, but at the same time there are reserves of hydrogen-containing raw materials (oil, natural gas).

They are used in very remote locations where it is easier to transport fuel than to stretch the cable. They can also start competing with power plants. It is the most powerful module installed in the world.

Almost every major automaker is working on a fuel cell electric vehicle project. This appears to be a much more promising concept than a conventional battery-powered electric vehicle because it does not require long recharging and the required infrastructure changes are not as extensive.

The advantages of fuel cells are also the availability of fuel, reliability (there are no moving parts in the fuel cell), durability and ease of use.

One of the main disadvantages of fuel cells today is their relatively high cost, but this disadvantage may soon be overcome - more and more companies produce commercial fuel cells, they are constantly being improved, and their cost is decreasing.

The growing importance of fuel cells is also supported by the fact that the Bush administration recently rethought its approach to car development, and the funds it spent on developing cars with the highest possible mileage have now been donated to fuel cell projects. Financing for development does not simply remain in the loins of the state.

Of course, the new drive concept is not limited to passenger cars, but we can also find it in mass transit. Fuel cell buses carry passengers on the streets of several cities. In addition to car drives, there are a number of smaller drives on the market such as powered computers, camcorders and mobile phones. In the figure, we see a fuel cell for powering traffic signaling.

The most efficient use of pure hydrogen as a fuel, however, will require the creation of a special infrastructure for its generation and transportation. All commercial designs currently use natural gas and similar fuels. Motor vehicles can use ordinary gasoline, which will preserve the existing developed network of filling stations. However, the use of such fuel leads to harmful emissions into the atmosphere (albeit very low) and complicates (and therefore increases the cost) of the fuel cell. In the future, the possibility of using environmentally friendly renewable energy sources (for example, solar energy or wind power) is being considered for decomposing water into hydrogen and oxygen by electrolysis, and then converting the resulting fuel in a fuel cell. Such combined plants operating in a closed cycle can provide a completely environmentally friendly, reliable, durable and efficient source of energy.

Mention should be made of the use of fuel cells in landfills, where they can burn gas emissions and help improve the environment in addition to generating electricity. Several test benches are currently in operation, and an extensive installation program for these facilities is being prepared at 150 proving grounds throughout the United States. Fuel cells are just useful devices and we are sure to see them more and more often.

Chemists have developed a catalyst that can replace expensive platinum in fuel cells. Instead, he uses about two hundred thousand cheap iron. Fuel cells convert chemical energy into electrical energy. Electrons in different molecules have different energies. The difference in energy when converting one molecule to another can be used as a source of energy. Just find a reaction in which the electrons move from higher to lower. Such reactions are the main source of energy for living organisms.

Another feature of fuel cells is that they are most efficient when both electrical and thermal energy are used simultaneously. However, the possibility of using thermal energy is not available at every facility. In the case of using fuel cells only for generating electrical energy, their efficiency decreases, although it exceeds the efficiency of "traditional" installations.

The most famous is respiration, which converts sugars into carbon dioxide and water. In a hydrogen fuel cell, two-atom hydrogen molecules combine with oxygen to form water. The energy difference between electrons in hydrogen and water is used to generate electricity. Hydrogen cells are probably the most commonly used vehicle today. Their massive expansion also prevents a small hook.

For an energetically rich reaction to take place, a catalyst is needed. Catalysts are molecules that increase the likelihood of a reaction occurring. It could also run without a catalyst, but less frequently or more slowly. Hydrogen cells use precious platinum as a catalyst.

History and modern use of fuel cells

The principle of operation of fuel cells was discovered in 1839. The English scientist William Grove (William Robert Grove, 1811-1896) discovered that the process of electrolysis - the decomposition of water into hydrogen and oxygen by means of an electric current - is reversible, that is, hydrogen and oxygen can be combined into water molecules without combustion, but with the release of heat and electric current. Grove called the device capable of such a reaction a "gas battery", which was the first fuel cell.

The same reaction as in hydrogen cells also occurs in living cells. Enzymes are relatively large molecules of amino acids that can be combined to form Lego bricks. Each enzyme has a so-called active site, in which the reaction is accelerated. Molecules other than amino acids are often present at the active site as well.

In the case of hydrogen acid, this is iron. A team of chemists, led by Morris Bullock of the US Department of Energy's Pacific Laboratory, has been able to mimic the reaction at an active hydrogenation site. Like the enzyme, hydrogenation is sufficient for platinum with iron. It can split 0.66 to 2 hydrogen molecules per second. The voltage difference is from 160 to 220 thousand volts. Both are comparable to the current platinum catalysts used in hydrogen cells. The reaction is carried out at room temperature.

The active development of fuel cell technology began after World War II, and it is associated with the aerospace industry. At this time, a search was conducted for an efficient and reliable, but at the same time sufficiently compact energy source. In the 1960s, NASA (National Aeronautics and Space Administration, NASA) specialists selected fuel cells as a source of energy for the Apollo (manned missions to the Moon), Apollo-Soyuz, Gemini and Skylab spacecraft. ... The Apollo was powered by three 1.5 kW (2.2 kW peak) units using cryogenic hydrogen and oxygen to generate electricity, heat and water. The weight of each installation was 113 kg. The three cells worked in parallel, but the energy generated by one unit was sufficient for a safe return. During 18 flights, the fuel cells have operated a total of 10,000 hours without any failures. Currently, fuel cells are used in the Space Shuttle, which uses three 12 W units to generate all of the electrical energy on board the spacecraft (Fig. 2). The water produced by the electrochemical reaction is used as drinking water and also for cooling equipment.

One kilogram of iron costs 0.5 kroons. Therefore, iron is 200 thousand times cheaper than platinum. Fuel cells may be cheaper in the future. Expensive platinum is not the only reason why they should not be used, at least not on a large scale. Handling it is difficult and dangerous.

If hydrogen chambers were to be used in bulk for driving cars, they would have to build the same infrastructure as gasoline and diesel. In addition, copper is required for the production of electric motors that power hydrogen-powered vehicles. However, this does not mean that fuel cells are useless. When there is oil, maybe we have nothing but to ride on hydrogen.

In our country, work was also carried out to create fuel cells for use in astronautics. For example, fuel cells were used to power the Soviet space shuttle Buran.

The development of methods for the commercial use of fuel cells began in the mid-1960s. These developments were partially funded by government agencies.

Currently, the development of technologies for the use of fuel cells goes in several directions. This is the creation of stationary power plants on fuel cells (for both centralized and decentralized energy supply), power plants of vehicles (samples of cars and buses on fuel cells have been created, including in our country) (Fig. 3), and also power supplies for various mobile devices (laptop computers, mobile phones, etc.) (Fig. 4).

Examples of the use of fuel cells in various fields are given in table. one.

One of the first commercial models of fuel cells intended for autonomous heating and power supply of buildings was the PC25 Model A, manufactured by ONSI Corporation (now United Technologies, Inc.). This 200 kW rated fuel cell is a Phosphoric Acid Fuel Cells (PAFC) type. The figure "25" in the model name means the serial number of the structure. Most of the previous models were experimental or test pieces, such as the 12.5 kW "PC11" that appeared in the 1970s. The new models increased the power taken from a separate fuel cell, and also reduced the cost of a kilowatt of energy produced. Currently, one of the most efficient commercial models is the PC25 Model C fuel cell. Like model "A", this is a fully automatic 200 kW PAFC type fuel cell designed to be installed directly at the serviced facility as an autonomous source of heat and power supply. Such a fuel cell can be installed outside the building. Outwardly, it is a parallelepiped 5.5 m long, 3 m wide and 3 m high, weighing 18 140 kg. The difference from previous models is an improved reformer and higher current density.

Table 1 Fuel cell application

Region application Nominal power Examples of using Stationary installations 5-250 kW and higher Autonomous sources of heat and power supply for residential, public and industrial buildings, uninterruptible power supplies, backup and emergency power supplies Portable installations 1-50 kW Road signs, cargo and rail refrigerators, wheelchairs, golf carts, spaceships and satellites Mobile installations 25-150 kW Cars (prototypes were created, for example, by DaimlerCrysler, FIAT, Ford, General Motors, Honda, Hyundai, Nissan, Toyota, Volkswagen, VAZ), buses ( eg "MAN", "Neoplan", "Renault") and other vehicles, warships and submarines Microdevices 1-500 W Mobile phones, laptops, personal digital assistants (PDAs), various consumer electronic devices, modern military devices

In some types of fuel cells, the chemical process can be reversed: when a potential difference is applied to the electrodes, water can be decomposed into hydrogen and oxygen, which are collected on porous electrodes. When a load is connected, such a regenerative fuel cell will begin to generate electrical energy.

A promising direction for the use of fuel cells is their use in conjunction with renewable energy sources, for example, photovoltaic panels or wind power plants. This technology allows you to completely avoid air pollution. A similar system is planned to be created, for example, at the Adam Joseph Lewis training center in Oberlin (see ABOK, 2002, No. 5, p. 10). Currently, solar panels are used as one of the energy sources in this building. Together with NASA specialists, a project was developed to use photovoltaic panels to obtain hydrogen and oxygen from water by electrolysis. Then hydrogen is used in fuel cells to generate electrical energy and. This will allow the building to keep all systems operational on cloudy days and at night.

How fuel cells work

Let's consider the principle of operation of a fuel cell using the example of the simplest cell with a proton exchange membrane (Proton Exchange Membrane, PEM). Such an element consists of a polymer membrane placed between the anode (positive electrode) and cathode (negative electrode) along with the anode and cathode catalysts. A polymer membrane is used as an electrolyte. The schematic of the PEM element is shown in Fig. five.

A proton exchange membrane (PEM) is a thin (about 2-7 sheets of plain paper) solid organic compound. This membrane functions as an electrolyte: it separates the substance into positively and negatively charged ions in the presence of water.

An oxidation process takes place at the anode, and a reduction process at the cathode. The anode and cathode in a PEM cell are made of a porous material that is a mixture of carbon and platinum particles. Platinum acts as a catalyst that promotes the dissociation reaction. The anode and cathode are made porous for free passage of hydrogen and oxygen through them, respectively.

The anode and cathode are placed between two metal plates, which supply hydrogen and oxygen to the anode and cathode, and remove heat and water, as well as electrical energy.

Hydrogen molecules pass through the channels in the plate to the anode, where the molecules are decomposed into individual atoms (Fig. 6).

	Figure 5. () Diagram of a fuel cell with a proton exchange membrane (PEM cell)
	Figure 6. () Hydrogen molecules pass through the channels in the plate to the anode, where the molecules are decomposed into individual atoms.
	Figure 7. () As a result of chemisorption in the presence of a catalyst, hydrogen atoms are converted into protons
	Figure 8. () Positively charged hydrogen ions diffuse through the membrane to the cathode, and the flow of electrons is directed to the cathode through an external electrical circuit to which the load is connected
	Figure 9. () Oxygen supplied to the cathode, in the presence of a catalyst, enters into a chemical reaction with hydrogen ions from the proton-exchange membrane and electrons from the external electrical circuit. Water is formed as a result of a chemical reaction

Then, as a result of chemisorption in the presence of a catalyst, hydrogen atoms, each donating one electron e -, are converted into positively charged hydrogen ions H +, ie, protons (Fig. 7).

Positively charged hydrogen ions (protons) diffuse through the membrane to the cathode, and the flow of electrons is directed to the cathode through an external electrical circuit to which the load (consumer of electrical energy) is connected (Fig. 8).

Oxygen supplied to the cathode, in the presence of a catalyst, enters into a chemical reaction with hydrogen ions (protons) from the proton-exchange membrane and electrons from the external electrical circuit (Fig. 9). As a result of a chemical reaction, water is formed.

The chemical reaction in a fuel cell of other types (for example, with an acidic electrolyte, which is a solution of phosphoric acid H 3 PO 4) is absolutely identical to the chemical reaction in a fuel cell with a proton-exchange membrane.

In any fuel cell, some of the energy of a chemical reaction is released as heat.

The flow of electrons in the external circuit is a direct current that is used to do work. Opening the external circuit or stopping the movement of hydrogen ions stops the chemical reaction.

The amount of electrical energy produced by a fuel cell depends on the type of fuel cell, geometric dimensions, temperature, and gas pressure. A separate fuel cell provides EMF less than 1.16 V. The size of fuel cells can be increased, however, in practice, several cells are used, connected in batteries (Fig. 10).

Fuel cell arrangement

Consider the design of a fuel cell using the PC25 Model C as an example. A schematic of the fuel cell is shown in Fig. eleven.

The PC25 Model C fuel cell consists of three main parts: the fuel processor, the actual power generation section and the voltage converter.

The main body of the fuel cell - the power generation section - is a stack of 256 individual fuel cells. The fuel cell electrodes include a platinum catalyst. These cells generate a direct current of 1,400 amperes at 155 volts. The battery is approximately 2.9 m long and 0.9 m wide and high.

Since the electrochemical process takes place at a temperature of 177 ° C, it is necessary to heat the battery at the time of start-up and remove heat from it during operation. For this, a separate water circuit is included in the fuel cell, and the battery is equipped with special cooling plates.

The fuel processor converts natural gas into hydrogen for an electrochemical reaction. This process is called reforming. The main element of the fuel processor is the reformer. In the reformer, natural gas (or other hydrogen-containing fuel) interacts with water vapor at high temperature (900 ° C) and high pressure in the presence of a catalyst - nickel. In this case, the following chemical reactions occur:

CH 4 (methane) + H 2 O 3H 2 + CO

(endothermic reaction, with heat absorption);

CO + H 2 O H 2 + CO 2

(the reaction is exothermic, with the release of heat).

The overall response is expressed by the equation:

CH 4 (methane) + 2H 2 O 4H 2 + CO 2

(the reaction is endothermic, with heat absorption).

To provide the high temperature required for natural gas conversion, part of the spent fuel from the fuel cell stack is directed to the burner, which maintains the required reformer temperature.

The steam required for reforming is generated from the condensate formed during the operation of the fuel cell. This uses the heat removed from the fuel cell stack (Fig. 12).

An unstable direct current is generated in the fuel cell stack, which is characterized by low voltage and high amperage. A voltage converter is used to convert it to industry standard AC. In addition, the voltage converter unit includes various control devices and safety interlock circuits that allow the fuel cell to be turned off in the event of various failures.

In such a fuel cell, approximately 40% of the fuel energy can be converted into electrical energy. About the same, about 40% of the energy of the fuel can be converted into thermal energy, which is then used as a heat source for heating, hot water supply and similar purposes. Thus, the total efficiency of such an installation can reach 80%.

An important advantage of such a source of heat and power supply is the possibility of its automatic operation. For maintenance, the owners of the facility where the fuel cell is installed do not need to maintain specially trained personnel - periodic maintenance can be carried out by employees of the operating organization.

Fuel cell types

Currently, several types of fuel cells are known, differing in the composition of the used electrolyte. The most widespread are the following four types (Table 2):

1. Fuel cells with a proton exchange membrane (Proton Exchange Membrane Fuel Cells, PEMFC).

2. Fuel cells based on phosphoric (phosphoric) acid (Phosphoric Acid Fuel Cells, PAFC).

3. Fuel cells based on molten carbonate (Molten Carbonate Fuel Cells, MCFC).

4. Solid oxide fuel cells (Solid Oxide Fuel Cells, SOFC). Currently, the largest fuel cell fleet is built on the basis of PAFC technology.

One of the key characteristics of different types of fuel cells is operating temperature. In many ways, it is temperature that determines the field of application of fuel cells. For example, high temperatures are critical for laptops, so proton exchange membrane fuel cells with low operating temperatures are being developed for this market segment.

For autonomous power supply of buildings, fuel cells of high installed power are required, and at the same time there is a possibility of using thermal energy, therefore, fuel cells of other types can also be used for these purposes.

Proton exchange membrane fuel cells (PEMFC)

These fuel cells operate at relatively low operating temperatures (60-160 ° C). They are distinguished by their high power density, allow quick adjustment of the output power, and can be quickly switched on. The disadvantage of this type of elements is the high requirements for the quality of the fuel, since contaminated fuel can damage the membrane. The rated power of this type of fuel cells is 1-100 kW.

Proton exchange membrane fuel cells were originally developed by General Electric in the 1960s for NASA. This type of fuel cell uses a solid-state polymer electrolyte called a Proton Exchange Membrane (PEM). Protons can move through the proton-exchange membrane, but electrons do not pass through it, as a result of which a potential difference arises between the cathode and the anode. Because of their simplicity and reliability, such fuel cells were used as a power source in the Gemini manned spacecraft.

This type of fuel cell is used as a power source for a wide variety of devices, including prototypes and prototypes, from mobile phones to buses and stationary power systems. The low operating temperature allows such cells to be used to power various types of complex electronic devices. Their use is less effective as a source of heat and power supply for public and industrial buildings, where large amounts of thermal energy are required. At the same time, such elements are promising as an autonomous source of power supply for small residential buildings such as cottages built in regions with hot climates.

table 2 Fuel cell types

Item type Workers temperature, ° C Efficiency output electric energy),% Total Efficiency,% Fuel cells with proton exchange membrane (PEMFC) 60–160 30–35 50–70 Fuel cells based on orthophosphoric (phosphoric) acid (PAFC) 150–200 35 70–80 Fuel cells based molten carbonate (MCFC) 600–700 45–50 70–80 Solid oxide fuel cells (SOFC) 700–1 000 50–60 70–80

Phosphoric Acid Fuel Cells (PAFC)

Fuel cells of this type were tested already in the early 1970s. Operating temperature range - 150-200 ° C. The main area of ​​application is autonomous sources of heat and power supply of average power (about 200 kW).

These fuel cells use a phosphoric acid solution as the electrolyte. The electrodes are made of carbon coated paper in which a platinum catalyst is dispersed.

The electrical efficiency of PAFC fuel cells is 37-42%. However, since these fuel cells operate at a sufficiently high temperature, it is possible to use the steam generated by the operation. In this case, the overall efficiency can reach 80%.

For energy production, hydrogen-containing feedstocks must be converted to pure hydrogen through a reforming process. For example, if gasoline is used as a fuel, then sulfur-containing compounds must be removed, since sulfur can damage the platinum catalyst.

Fuel cells of the PAFC type were the first commercial fuel cells to be economically justified. The most common model is the 200 kW PC25 fuel cell manufactured by ONSI Corporation (now United Technologies, Inc.) (Fig. 13). For example, these elements are used as a source of heat and electricity at a police station in Central Park in New York, or as a supplemental source of energy for the Conde Nast Building & Four Times Square. The largest plant of this type is being tested as an 11 MW power plant in Japan.

Phosphoric acid fuel cells are also used as an energy source in vehicles. For example, in 1994, H-Power Corp., Georgetown University and the US Department of Energy equipped a bus with a 50 kW power plant.

Molten Carbonate Fuel Cells (MCFC)

Fuel cells of this type operate at very high temperatures - 600-700 ° C. These operating temperatures allow fuel to be used directly in the cell itself, without the need for a separate reformer. This process is called "internal reforming". It significantly simplifies the design of the fuel cell.

Fuel cells based on molten carbonate require a significant start-up time and do not allow for prompt regulation of the output power; therefore, the main area of ​​their application is large stationary sources of thermal and electrical energy. However, they are distinguished by high efficiency of fuel conversion - 60% electrical efficiency and up to 85% overall efficiency.

In this type of fuel cell, the electrolyte consists of potassium carbonate and lithium carbonate salts, heated to about 650 ° C. Under these conditions, the salts are in a molten state, forming an electrolyte. At the anode, hydrogen interacts with CO 3 ions, forming water, carbon dioxide and releasing electrons, which are sent to the external circuit, and at the cathode, oxygen interacts with carbon dioxide and electrons from the external circuit, again forming CO 3 ions.

Laboratory samples of this type of fuel cells were created in the late 1950s by Dutch scientists G. H. J. Broers and J. A. A. Ketelaar. In the 1960s, engineer Francis T. Bacon, a descendant of the famous English writer and scientist of the 17th century, worked with these elements, which is why sometimes MCFC fuel cells are called Bacon cells. NASA's Apollo, Apollo-Soyuz and Scylab programs used just such fuel cells as a power source (Fig. 14). In the same years, the US military tested several samples of MCFC fuel cells from Texas Instruments, which used military grade gasoline as fuel. In the mid-1970s, the US Department of Energy began research aimed at creating a stationary molten carbonate fuel cell suitable for practical use. In the 1990s, a number of commercial units with a nominal capacity of up to 250 kW were put into operation, for example, at the US Navy's Miramar Air Force Base in California. In 1996, FuelCell Energy, Inc. commissioned a 2 MW nominal pre-production unit in Santa Clara, California.

Solid State Oxide Fuel Cells (SOFC)

Solid-state oxide fuel cells are simple in design and operate at very high temperatures - 700-1000 ° C. These high temperatures allow the use of relatively "dirty", crude fuel. The same features as those of fuel cells based on molten carbonate determine a similar field of application - large stationary sources of thermal and electrical energy.

Solid oxide fuel cells are structurally different from PAFC and MCFC fuel cells. The anode, cathode and electrolyte are made of special ceramics. The most commonly used electrolyte is a mixture of zirconium oxide and calcium oxide, but other oxides can be used as well. The electrolyte forms a crystal lattice covered on both sides with a porous electrode material. Structurally, such elements are made in the form of tubes or flat boards, which makes it possible to use technologies widely used in the electronics industry in their manufacture. As a result, solid-state oxide fuel cells can operate at very high temperatures and are therefore advantageous for the production of both electrical and thermal energy.

At high operating temperatures, oxygen ions are formed at the cathode, which migrate through the crystal lattice to the anode, where they interact with hydrogen ions, forming water and releasing free electrons. In this case, hydrogen is released from natural gas directly in the cell, i.e. there is no need for a separate reformer.

The theoretical foundations for the creation of solid-state oxide fuel cells were laid back in the late 1930s, when Swiss scientists Emil Bauer and H. Preis experimented with zirconium, yttrium, cerium, lanthanum and tungsten, using them as electrolytes.

The first prototypes of such fuel cells were created in the late 1950s by a number of American and Dutch companies. Most of these companies soon abandoned further research due to technological difficulties, but one of them, Westinghouse Electric Corp. (now Siemens Westinghouse Power Corporation) continued work. The company is currently accepting pre-orders for a commercial tubular solid-state fuel cell model, which is expected to be released this year (Figure 15). The market segment for such elements is stationary installations for the production of heat and electricity with a capacity of 250 kW to 5 MW.

Fuel cells of the SOFC type have demonstrated very high reliability. For example, a Siemens Westinghouse fuel cell prototype has run 16,600 hours and continues to run, making it the longest continuous fuel cell life in the world.

The high temperature, high pressure mode of operation of SOFC fuel cells allows the creation of hybrid plants in which the fuel cell emissions drive gas turbines used to generate electricity. The first such hybrid plant is in operation in Irvine, California. The rated power of this installation is 220 kW, of which 200 kW from a fuel cell and 20 kW from a microturbine generator.

Fuel cell Is an electrochemical device, similar to a galvanic cell, but different from it in that substances for an electrochemical reaction are supplied to it from the outside - in contrast to the limited amount of energy stored in a galvanic cell or battery.

Rice. one. Some fuel cells

Fuel cells convert the chemical energy of the fuel into electricity, bypassing ineffective combustion processes that go with large losses. They convert hydrogen and oxygen into electricity as a result of a chemical reaction. As a result of this process, water is formed and a large amount of heat is released. A fuel cell is very similar to a battery, which can be charged and then used up with stored electrical energy. The inventor of the fuel cell is believed to be William R. Grove, who invented it back in 1839. In this fuel cell, a sulfuric acid solution was used as an electrolyte, and hydrogen was used as a fuel, which was combined with oxygen in an oxidizing medium. Until recently, fuel cells were used only in laboratories and on spacecraft.

Unlike other generators of electricity, such as internal combustion engines or turbines that run on gas, coal, fuel oil, etc., fuel cells do not burn fuel. This means no noisy high pressure rotors, no loud exhaust noise, no vibrations. Fuel cells generate electricity through a silent electrochemical reaction. Another feature of fuel cells is that they convert the chemical energy of the fuel directly into electricity, heat and water.

Fuel cells are highly efficient and do not produce large amounts of greenhouse gases such as carbon dioxide, methane and nitric oxide. The only emissions produced by fuel cells are water in the form of steam and a small amount of carbon dioxide, which is not emitted at all if pure hydrogen is used as the fuel. Fuel cells are assembled into assemblies and then into separate functional modules.

Fuel cells have no moving parts (at least within the cell itself) and therefore do not obey Carnot's law. That is, they will have greater than 50% efficiency and are especially effective at low loads. Thus, fuel cell vehicles can (and have already been proven) more economical than conventional vehicles under real-world driving conditions.

The fuel cell generates a constant voltage electrical current that can be used to drive an electric motor, lighting fixtures, and other electrical systems in a vehicle.

There are several types of fuel cells that differ in the chemical processes used. Fuel cells are usually classified by the type of electrolyte they use.

Some types of fuel cells are promising for use as power plants for power plants, while others for portable devices or for driving cars.

1. Alkaline fuel cells (SHFC)

Alkaline fuel cell- this is one of the very first elements developed. Alkaline fuel cells (ALFC) are one of the most studied technologies used by NASA in the Apollo and Space Shuttle programs since the mid-1960s. Aboard these spaceships, fuel cells produce electricity and drinking water.

Alkaline fuel cells are one of the most efficient elements used to generate electricity, with power generation efficiency reaching up to 70%.

Alkaline fuel cells use an electrolyte, that is, an aqueous solution of potassium hydroxide contained in a porous stabilized matrix. The concentration of potassium hydroxide can vary depending on the operating temperature of the fuel cell, which ranges from 65 ° C to 220 ° C. The charge carrier in SHFC is a hydroxyl ion (OH-), which moves from the cathode to the anode, where it reacts with hydrogen, producing water and electrons. The water produced at the anode moves back to the cathode, again generating hydroxyl ions there. This series of reactions in the fuel cell produces electricity and, as a by-product, heat:

Reaction at the anode: 2H2 + 4OH- => 4H2O + 4e

Cathode reaction: O2 + 2H2O + 4e- => 4OH

General system response: 2H2 + O2 => 2H2O

The advantage of SHFCs is that these fuel cells are the cheapest in production, since the catalyst that is needed on the electrodes can be any of the substances that are cheaper than those that are used as catalysts for other fuel cells. In addition, SCHE operate at a relatively low temperature and are among the most efficient.

One of the characteristic features of SHFC is its high sensitivity to CO2, which can be contained in fuel or air. CO2 reacts with the electrolyte, quickly poisons it, and greatly reduces the efficiency of the fuel cell. Therefore, the use of SHTE is limited to closed spaces, such as space and underwater vehicles, they operate on pure hydrogen and oxygen.

2. Fuel cells based on molten carbonate (RKTE)

Fuel cells with molten carbonate electrolyte are high temperature fuel cells. The high operating temperature allows natural gas to be used directly without a processor fuel and low calorific value fuel gas for industrial processes and other sources. This process was developed in the mid-60s of the twentieth century. Since then, production technology, performance and reliability have been improved.

The operation of RKTE is different from other fuel cells. These cells use an electrolyte from a mixture of molten carbonate salts. Currently, there are two types of mixtures in use: lithium carbonate and potassium carbonate or lithium carbonate and sodium carbonate. To melt carbonate salts and achieve a high degree of ion mobility in the electrolyte, fuel cells with molten carbonate electrolyte operate at high temperatures (650 ° C). The efficiency varies between 60-80%.

When heated to 650 ° C, the salts become a conductor for carbonate ions (CO32-). These ions travel from the cathode to the anode, where they combine with hydrogen to form water, carbon dioxide and free electrons. These electrons are channeled back to the cathode through an external electrical circuit, generating electrical current and heat as a by-product.

Anode reaction: CO32- + H2 => H2O + CO2 + 2e

Cathode reaction: CO2 + 1 / 2O2 + 2e- => CO32-

General reaction of the element: H2 (g) + 1 / 2O2 (g) + CO2 (cathode) => H2O (g) + CO2 (anode)

The high operating temperatures of molten carbonate electrolyte fuel cells have certain advantages. The advantage is the ability to use standard materials (stainless steel sheet and nickel catalyst on the electrodes). The waste heat can be used to generate high pressure steam. High reaction temperatures in the electrolyte also have their advantages. The use of high temperatures takes a long time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. These characteristics allow the use of fuel cell installations with molten carbonate electrolyte under constant power conditions. High temperatures prevent carbon monoxide damage to the fuel cell, poisoning, etc.

Molten carbonate electrolyte fuel cells are suitable for use in large stationary installations. Thermal power plants with an output electric power of 2.8 MW are industrially produced. Installations with an output power of up to 100 MW are being developed.

3. Fuel cells based on phosphoric acid (FCTE)

Fuel cells based on phosphoric (orthophosphoric) acid became the first fuel cells for commercial use. This process was developed in the mid 60s of the twentieth century, tests have been carried out since the 70s of the twentieth century. As a result, stability and performance have been increased and cost has been reduced.

Fuel cells based on phosphoric (orthophosphoric) acid use an electrolyte based on phosphoric acid (H3PO4) with a concentration of up to 100%. The ionic conductivity of phosphoric acid is low at low temperatures, therefore these fuel cells are used at temperatures up to 150-220 ° C.

The charge carrier in this type of fuel cell is hydrogen (H +, proton). A similar process occurs in fuel cells with a proton exchange membrane (MOPTE), in which the hydrogen supplied to the anode is separated into protons and electrons. Protons travel through the electrolyte and combine with oxygen from the air at the cathode to form water. Electrons are channeled through an external electrical circuit, generating an electrical current. Below are the reactions that generate electricity and heat.

Reaction at the anode: 2H2 => 4H + + 4e

Cathode reaction: O2 (g) + 4H + + 4e- => 2H2O

General reaction of the element: 2H2 + O2 => 2H2O

The efficiency of fuel cells based on phosphoric (orthophosphoric) acid is more than 40% when generating electrical energy. With combined heat and power generation, the overall efficiency is around 85%. In addition, given the operating temperatures, the waste heat can be used to heat water and generate steam at atmospheric pressure.

The high performance of thermal power plants on fuel cells based on phosphoric (orthophosphoric) acid in the combined production of heat and electricity is one of the advantages of this type of fuel cells. The plants use carbon monoxide with a concentration of about 1.5%, which significantly expands the choice of fuel. Simple design, low electrolyte volatility and increased stability are also advantages of such fuel cells.

Thermal power plants with an output electric power of up to 400 kW are industrially produced. Installations with a capacity of 11 MW have been tested accordingly. Installations with an output power of up to 100 MW are being developed.

4. Fuel cells with a proton exchange membrane (MOPTE)

Fuel cells with proton exchange membrane are considered the best type of fuel cells for generating power for vehicles, which can replace gasoline and diesel internal combustion engines. These fuel cells were first used by NASA for the Gemini program. Installations on MOPTE have been developed and shown with a capacity of 1 W to 2 kW.

The electrolyte in these fuel cells is a solid polymer membrane (thin plastic film). When impregnated with water, this polymer allows protons to pass through but does not conduct electrons.

The fuel is hydrogen, and the charge carrier is a hydrogen ion (proton). At the anode, a hydrogen molecule is split into a hydrogen ion (proton) and electrons. Hydrogen ions pass through the electrolyte to the cathode, while electrons move around the outer circle and produce electrical energy. Oxygen, which is taken from the air, is fed to the cathode and combines with electrons and hydrogen ions to form water. The following reactions take place on the electrodes: Reaction at the anode: 2H2 + 4OH- => 4H2O + 4e Reaction at the cathode: O2 + 2H2O + 4e- => 4OH Total cell reaction: 2H2 + O2 => 2H2O Compared to other types of fuel cells, fuel cells a proton exchange membrane produces more energy for a given volume or weight of a fuel cell. This feature allows them to be compact and lightweight. In addition, the operating temperature is less than 100 ° C, which allows for quick start-up of operation. These characteristics, as well as the ability to quickly change energy output, are just a few of what makes these fuel cells a prime candidate for vehicle use.

Another advantage is that the electrolyte is solid and not liquid. It is easier to keep gases at the cathode and anode with a solid electrolyte, so such fuel cells are cheaper to manufacture. When using a solid electrolyte, there are no such difficulties as orientation and fewer problems due to the occurrence of corrosion, which increases the life of the cell and its components.

5. Solid oxide fuel cells (SOFC)

Solid oxide fuel cells are the fuel cells with the highest operating temperature. The operating temperature can be varied from 600 ° C to 1000 ° C, which allows different types of fuel to be used without special pre-treatment. To handle these high temperatures, the electrolyte used is a thin, ceramic-based solid metal oxide, often an alloy of yttrium and zirconium, which is a conductor of oxygen (O2-) ions. The technology of using solid oxide fuel cells has been developing since the late 1950s and has two configurations: planar and tubular.

Solid electrolyte provides a hermetically sealed transition of gas from one electrode to another, while liquid electrolytes are located in a porous substrate. The charge carrier in this type of fuel cell is an oxygen ion (O2-). At the cathode, oxygen molecules from the air are separated into an oxygen ion and four electrons. Oxygen ions pass through the electrolyte and combine with hydrogen to form four free electrons. Electrons are channeled through an external electrical circuit, generating electrical current and waste heat.

Reaction at the anode: 2H2 + 2O2- => 2H2O + 4e

Cathode reaction: O2 + 4e- => 2O2-

General reaction of the element: 2H2 + O2 => 2H2O

The efficiency of electric power generation is the highest of all fuel cells - about 60%. In addition, the high operating temperatures enable combined heat and power generation to generate high pressure steam. Combining a high-temperature fuel cell with a turbine makes it possible to create a hybrid fuel cell to increase the efficiency of electric power generation by up to 70%.

Solid oxide fuel cells operate at very high temperatures (600 ° C-1000 ° C), which takes a long time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. At such high operating temperatures, a converter is not required to recover hydrogen from the fuel, which allows the thermal power plant to operate with relatively unclean fuels resulting from the gasification of coal or waste gases and the like. Also, this fuel cell is excellent for high power operation, including industrial and large central power plants. Modules with an output electrical power of 100 kW are commercially produced.

6. Fuel cells with direct methanol oxidation (POMTE)

Fuel cells with direct methanol oxidation They are successfully used in the field of power supply of mobile phones, laptops, as well as for the creation of portable power sources, which is what the future use of such elements is aimed at.

The design of fuel cells with direct methanol oxidation is similar to the design of fuel cells with a proton exchange membrane (MOPTE), i.e. a polymer is used as an electrolyte, and a hydrogen ion (proton) is used as a charge carrier. But liquid methanol (CH3OH) is oxidized in the presence of water at the anode with the release of CO2, hydrogen ions and electrons, which are directed along an external electrical circuit, while an electric current is generated. Hydrogen ions pass through the electrolyte and reacts with oxygen from the air and electrons from the external circuit to form water at the anode.

Reaction at the anode: CH3OH + H2O => CO2 + 6H + + 6e Reaction at the cathode: 3 / 2O2 + 6H + + 6e- => 3H2O General reaction of the element: CH3OH + 3 / 2O2 => CO2 + 2H2O The development of such fuel cells was carried out from the beginning90- x years of the twentieth century, and their power density and efficiency were increased to 40%.

These elements were tested in a temperature range of 50-120 ° C. Because of the low operating temperatures and the lack of the need for a converter, such fuel cells are the best candidate for applications in mobile phones and other consumer goods, as well as in automobile engines. Their advantage is also small size.

7. Polymer electrolyte fuel cells (PETE)

In the case of polymer electrolyte fuel cells, the polymer membrane consists of polymer fibers with water regions in which the conductivity of water ions exists. H2O + (proton, red) is attached to the water molecule. Water molecules pose a problem due to their slow ion exchange. Therefore, a high concentration of water is required both in the fuel and at the outlet electrodes, which limits the operating temperature to 100 ° C.

8. Solid acid fuel cells (TKTE)

In solid acid fuel cells, the electrolyte (CsHSO4) does not contain water. The operating temperature is therefore 100-300 ° C. Rotation of oxyanions SO42-allows protons (red) to move as shown in the figure. Typically, a solid acid fuel cell is a sandwich in which a very thin layer of a solid acid compound is sandwiched between two tightly compressed electrodes to ensure good contact. When heated, the organic component evaporates, leaving through the pores in the electrodes, retaining the ability of multiple contacts between the fuel (or oxygen at the other end of the cells), electrolyte and electrodes.

9. Comparison of the most important characteristics of fuel cells

Fuel cell characteristics

Fuel cell type	Working temperature	Power generation efficiency	Fuel type	Scope of application
				Medium and large installations
			Pure hydrogen	installations
			Pure hydrogen	Small installations
			Most hydrocarbon fuels	Small, medium and large installations
				Portable installations
			Pure hydrogen	Space investigating
			Pure hydrogen	Small installations

10. Use of fuel cells in cars