From the point of view of "green" energy, hydrogen fuel cells have an extremely high efficiency - 60%. For comparison: efficiency of the best engines internal combustion is 35-40%. For solar power plants, the coefficient is only 15-20%, but it is highly dependent on weather conditions. The efficiency of the best vane wind farms reaches 40%, which is comparable to steam generators, but wind turbines also require suitable weather conditions and expensive maintenance.

As we can see, according to this parameter, hydrogen energy is the most attractive source of energy, but there are still a number of problems that prevent its mass application. The most important of them is the process of hydrogen production.

Production problems

Hydrogen energy is environmentally friendly, but not autonomous. To work, a fuel cell needs hydrogen, which is not found on Earth in its pure form. Hydrogen needs to be obtained, but all currently existing methods are either very expensive or ineffective.

The most efficient method in terms of the amount of hydrogen produced per unit of energy expended is the steam reforming of natural gas. Methane is combined with water vapor at a pressure of 2 MPa (about 19 atmospheres, i.e. pressure at a depth of about 190 m) and a temperature of about 800 degrees, resulting in a converted gas with a hydrogen content of 55-75%. Steam reforming requires huge plants that can only be used in production.

The tube furnace for steam reforming of methane is not the most ergonomic way to produce hydrogen. Source: CTK-Euro

A more convenient and simple method is water electrolysis. When an electric current passes through the treated water, a series of electrochemical reactions occur, resulting in the formation of hydrogen. A significant disadvantage of this method is the high energy consumption required for the reaction. That is, it turns out a somewhat strange situation: to obtain hydrogen energy, you need ... energy. In order to avoid unnecessary costs during electrolysis and save valuable resources, some companies are seeking to develop full-cycle "electricity - hydrogen - electricity" systems in which energy generation becomes possible without external replenishment. An example of such a system is the development of Toshiba H2One.

Toshiba H2One mobile power station

We have developed the H2One mobile mini power plant that converts water into hydrogen and hydrogen into energy. To maintain electrolysis, it uses solar panels, and excess energy is stored in batteries and ensures the operation of the system in the absence of sunlight. The resulting hydrogen is either fed directly to the fuel cells or stored in an integrated tank. H2One electrolyzer generates up to 2 m 3 of hydrogen per hour, and at the output it provides power up to 55 kW. For the production of 1 m 3 of hydrogen, the station requires up to 2.5 m 3 of water.

While the H2One station is not able to provide electricity to a large enterprise or whole city, but for the functioning of small areas or organizations, its energy will be quite enough. Thanks to its mobility, it can also be used as a temporary solution in natural Disasters or an emergency power outage. In addition, unlike a diesel generator, which needs fuel to function normally, a hydrogen power plant needs only water.

Currently Toshiba H2One is used only in a few cities in Japan - for example, it supplies electricity and hot water to a railway station in the city of Kawasaki.

Installation of the H2One system in Kawasaki

Hydrogen future

Now hydrogen fuel cells provide energy for portable power banks, city buses with cars, and rail transport. (We will cover more about the use of hydrogen in the automotive industry in our next post). Hydrogen fuel cells unexpectedly turned out to be an excellent solution for quadcopters - with the same mass as the battery, the hydrogen supply provides up to five times longer flight time. In this case, frost does not affect efficiency in any way. Experimental fuel cell drones produced by the Russian company AT Energy were used for filming at the Sochi Olympics.

It became known that at the upcoming Olympic Games in Tokyo, hydrogen will be used in cars, in the production of electricity and heat, and will also become the main source of energy for the Olympic village. To do this, by order of Toshiba Energy Systems & Solutions Corp. In the Japanese city of Namie, one of the world's largest hydrogen production stations is being built. The station will consume up to 10 MW of energy obtained from "green" sources, generating up to 900 tons of hydrogen per year by electrolysis.

Hydrogen energy is our “reserve for the future”, when fossil fuels will have to be completely abandoned, and renewable energy sources will not be able to cover the needs of mankind. According to the Markets&Markets forecast, the volume of world hydrogen production, which now stands at $115 billion, will grow to $154 billion by 2022. But in the near future, the mass introduction of the technology is unlikely to happen, it is still necessary to solve a number of problems associated with the production and operation of special power plants, to reduce their cost . When technological barriers are overcome, hydrogen energy will reach a new level and, perhaps, will be as widespread as traditional or hydropower today.

fuel cells Fuel cells are chemical power sources. They carry out the direct conversion of fuel energy into electricity, bypassing inefficient, high-loss combustion processes. This electrochemical device, as a result of highly efficient "cold" combustion of fuel, directly generates electricity.

Biochemists have established that a biological hydrogen-oxygen fuel cell is "built into" every living cell (see Chapter 2).

The source of hydrogen in the body is food - fats, proteins and carbohydrates. In the stomach, intestines, cells, it ultimately decomposes to monomers, which, in turn, after a series of chemical transformations give hydrogen attached to the carrier molecule.

Oxygen from the air enters the blood through the lungs, combines with hemoglobin and is carried to all tissues. The process of combining hydrogen with oxygen is the basis of the body's bioenergetics. Here, under mild conditions (room temperature, normal pressure, aquatic environment), chemical energy with high efficiency is converted into thermal, mechanical (muscle movement), electricity (electric ramp), light (insects emitting light).

Man once again repeated the device for obtaining energy created by nature. At the same time, this fact indicates the prospects of the direction. All processes in nature are very rational, so steps towards the real use of fuel cells inspire hope for the energy future.

The discovery in 1838 of a hydrogen-oxygen fuel cell belongs to the English scientist W. Grove. Investigating the decomposition of water into hydrogen and oxygen, he discovered a side effect - the electrolyzer produced electricity.

What burns in a fuel cell?
Fossil fuels (coal, gas and oil) are mostly carbon. During combustion, fuel atoms lose electrons, and air oxygen atoms gain them. So in the process of oxidation, carbon and oxygen atoms are combined into combustion products - carbon dioxide molecules. This process is vigorous: the atoms and molecules of the substances involved in combustion acquire high speeds, and this leads to an increase in their temperature. They begin to emit light - a flame appears.

The chemical reaction of carbon combustion has the form:

C + O2 = CO2 + heat

During combustion, chemical energy is converted into thermal energy due to the exchange of electrons between the atoms of the fuel and the oxidizer. This exchange occurs randomly.

Combustion is the exchange of electrons between atoms, and electric current is the directed movement of electrons. If in the process chemical reaction cause the electrons to do work, the temperature of the combustion process will decrease. In FC, electrons are taken from the reactants at one electrode, give up their energy in the form of an electric current, and join the reactants at the other.

The basis of any HIT is two electrodes connected by an electrolyte. A fuel cell consists of an anode, a cathode, and an electrolyte (see Chap. 2). Oxidizes at the anode, i.e. donates electrons, the reducing agent (CO or H2 fuel), free electrons from the anode enter the external circuit, and positive ions are retained at the anode-electrolyte interface (CO+, H+). From the other end of the chain, the electrons approach the cathode, on which the reduction reaction takes place (the addition of electrons by the oxidizing agent O2–). The oxidant ions are then carried by the electrolyte to the cathode.

In FC, three phases of the physicochemical system are brought together:

gas (fuel, oxidizer);
electrolyte (conductor of ions);
metal electrode (conductor of electrons).
In fuel cells, the energy of the redox reaction is converted into electrical energy, and the processes of oxidation and reduction are spatially separated by an electrolyte. The electrodes and electrolyte do not participate in the reaction, but in real designs they become contaminated with fuel impurities over time. Electrochemical combustion can proceed at low temperatures and practically without losses. On fig. p087 shows the situation in which a mixture of gases (CO and H2) enters the fuel cell, i.e. it can burn gaseous fuel (see Chap. 1). Thus, TE turns out to be "omnivorous".

The use of fuel cells is complicated by the fact that fuel must be “prepared” for them. For fuel cells, hydrogen is obtained by conversion of organic fuel or coal gasification. Therefore, the block diagram of a power plant on a fuel cell, except for the batteries of a fuel cell, a converter direct current in variable (see Ch. 3) and auxiliary equipment includes a hydrogen production unit.

Two directions of FC development

There are two areas of application of fuel cells: autonomous and large-scale energy.

For autonomous use, specific characteristics and ease of use are the main ones. The cost of generated energy is not the main indicator.

For a large power generation, efficiency is a decisive factor. In addition, the installations must be durable, do not contain expensive materials and use natural fuels with minimal preparation costs.

The greatest benefits are offered by the use of fuel cells in a car. Here, as nowhere else, the compactness of fuel cells will have an effect. With the direct receipt of electricity from fuel, the saving of the latter will be about 50%.

For the first time, the idea of ​​using fuel cells in large-scale power engineering was formulated by the German scientist W. Oswald in 1894. Later, the idea of ​​creating efficient sources of autonomous energy based on a fuel cell was developed.

After that, repeated attempts were made to use coal as an active substance in fuel cells. In the 1930s, the German researcher E. Bauer created a laboratory prototype of a fuel cell with a solid electrolyte for direct anodic oxidation of coal. At the same time, oxygen-hydrogen fuel cells were studied.

In 1958, in England, F. Bacon created the first oxygen-hydrogen plant with a capacity of 5 kW. But it was cumbersome due to the use of high gas pressure (2 ... 4 MPa).

Since 1955, K. Kordesh has been developing low-temperature oxygen-hydrogen fuel cells in the USA. They used carbon electrodes with platinum catalysts. In Germany, E. Yust worked on the creation of non-platinum catalysts.

After 1960, demonstration and advertising samples were created. The first practical application of fuel cells was found on the Apollo spacecraft. They were the main power plants for powering the onboard equipment and provided the astronauts with water and heat.

The main areas of use for off-grid FC installations have been military and naval applications. At the end of the 1960s, the volume of research on fuel cells decreased, and after the 1980s, it increased again in relation to large-scale energy.

VARTA has developed FCs using double-sided gas diffusion electrodes. Electrodes of this type are called "Janus". Siemens has developed electrodes with power density up to 90 W/kg. In the United States, work on oxygen-hydrogen cells is being carried out by United Technology Corp.

In the large-scale power industry, the use of fuel cells for large-scale energy storage, for example, the production of hydrogen (see Chap. 1), is very promising. (sun and wind) are dispersed (see Ch. 4). Their serious use, which is indispensable in the future, is unthinkable without capacious batteries that store energy in one form or another.

The problem of accumulation is already relevant today: daily and weekly fluctuations in the load of power systems significantly reduce their efficiency and require the so-called maneuverable capacities. One of the options for an electrochemical energy storage is a fuel cell in combination with electrolyzers and gas holders*.

* Gas ​​holder [gas + English. holder] - storage for large quantities of gas.

The first generation of TE

Medium-temperature fuel cells of the first generation, operating at a temperature of 200...230°C on liquid fuel, natural gas or technical hydrogen*, have reached the greatest technological perfection. The electrolyte in them is phosphoric acid, which fills the porous carbon matrix. The electrodes are made of carbon and the catalyst is platinum (platinum is used in amounts on the order of a few grams per kilowatt of power).

* Commercial hydrogen is a fossil fuel conversion product containing minor impurities of carbon monoxide.

One such power plant was put into operation in the state of California in 1991. It consists of eighteen batteries weighing 18 tons each and is placed in a case with a diameter of just over 2 m and a height of about 5 m. The battery replacement procedure has been thought out using a frame structure moving along rails.

The United States delivered two power plants to Japan to Japan. The first of them was launched in early 1983. The operational performance of the station corresponded to the calculated ones. She worked with a load of 25 to 80% of the nominal. The efficiency reached 30...37% - this is close to modern large thermal power plants. Its start-up time from a cold state is from 4 hours to 10 minutes, and the duration of power change from zero to full is only 15 seconds.

Now in different parts of the United States, small combined heat and power plants with a capacity of 40 kW with a fuel utilization factor of about 80% are being tested. They can heat water up to 130°C and are placed in laundries, sports complexes, at points of contact, etc. About a hundred installations have already worked for a total of hundreds of thousands of hours. The environmental friendliness of FC power plants allows them to be placed directly in cities.

The first fuel power plant in New York, with a capacity of 4.5 MW, occupied an area of ​​1.3 hectares. Now, for new plants with a capacity of two and a half times more, a site measuring 30x60 m is needed. Several demonstration power plants with a capacity of 11 MW are being built. The construction time (7 months) and the area (30x60 m) occupied by the power plant are striking. The estimated service life of new power plants is 30 years.

Second and third generation fuel cells

The best characteristics are already being designed modular plants with a capacity of 5 MW with medium-temperature fuel cells of the second generation. They operate at temperatures of 650...700°C. Their anodes are made from sintered particles of nickel and chromium, cathodes are made from sintered and oxidized aluminum, and the electrolyte is a mixture of lithium and potassium carbonates. Elevated temperature helps solve two major electrochemical problems:

reduce the "poisoning" of the catalyst by carbon monoxide;
increase the efficiency of the process of reduction of the oxidizer at the cathode.
High-temperature fuel cells of the third generation with an electrolyte of solid oxides (mainly zirconium dioxide) will be even more efficient. Their operating temperature is up to 1000°C. The efficiency of power plants with such fuel cells is close to 50%. Here, the products of gasification of hard coal with a significant content of carbon monoxide are also suitable as fuel. Equally important, waste heat from high-temperature plants can be used to produce steam to drive turbines for electric generators.

Vestingaus has been in the solid oxide fuel cell business since 1958. It develops power plants with a capacity of 25 ... 200 kW, in which gaseous fuel from coal can be used. Experimental installations with a capacity of several megawatts are being prepared for testing. Another American firm, Engelgurd, is designing 50 kW fuel cells that run on methanol with phosphoric acid as the electrolyte.

More and more firms all over the world are involved in the creation of fuel cells. The American United Technology and the Japanese Toshiba formed the International Fuel Cells Corporation. In Europe, the Belgian-Dutch consortium Elenko, the West German company Siemens, the Italian Fiat, and the British Jonson Metju are engaged in fuel cells.

Viktor LAVRUS.

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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 occur. Hydrogen and oxygen are supplied to the fuel cells, and the output is electricity, water and heat. Their advantages include environmental friendliness, reliability, durability and ease of operation. Unlike conventional batteries, electrochemical converters can operate virtually indefinitely as long as fuel is available. They do not need to be charged for hours until fully charged. Moreover, the cells themselves can charge the battery while the car is parked with the engine off.

Proton membrane fuel cells (PEMFC) and solid oxide fuel cells (SOFC) are the most widely used in hydrogen vehicles.

A fuel cell with a proton exchange membrane operates as follows. Between the anode and cathode are a special membrane and a platinum-coated catalyst. Hydrogen enters the anode, and oxygen enters the cathode (for example, from air). At the anode, hydrogen is decomposed into protons and electrons with the help of a catalyst. Hydrogen protons pass through the membrane and enter the cathode, while electrons are given off to the external circuit (the membrane does not let them through). The potential difference thus obtained 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 car exhaust gases. Possessing a high efficiency, PEM cells have one significant drawback - their operation requires pure hydrogen, the storage of which is a rather serious problem.

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

Solid oxide cells

Solid oxide SOFC cells are much less demanding on fuel purity. In addition, thanks to the use of a POX reformer (Partial Oxidation - partial oxidation), such cells can consume ordinary 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 releases hydrogen and carbon dioxide. Further, also under the influence of temperature and with the help of SOFC itself (consisting of a porous ceramic material based on zirconium oxide), hydrogen is oxidized by oxygen in the air. After hydrogen is obtained 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 foreign impurities in the original fuel. So the quality of 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. However, 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 you to achieve the required voltage by connecting a set of standard cells in series. And, perhaps most importantly, from the point of view of the introduction of such devices, there are no very expensive platinum-based electrodes in SOFC. 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 such types of fuel cells:

• A.F.C.– Alkaline Fuel Cell (alkaline fuel cell);
• PAFC– Phosphoric Acid Fuel Cell (phosphoric acid fuel cell);
• PEMFC– Proton Exchange Membrane Fuel Cell (fuel cell with a proton exchange membrane);
• DMFC– Direct Methanol Fuel Cell (fuel cell with direct methanol decomposition);
• MCFC– Molten Carbonate Fuel Cell (fuel cell of molten carbonate);
• SOFC– Solid Oxide Fuel Cell (solid oxide fuel cell).

Benefits of fuel cells/cells

A fuel cell/cell is a device that efficiently generates direct current and heat from a hydrogen-rich fuel through an electrochemical reaction.

A fuel cell is similar to a battery in that it generates direct current through a chemical reaction. The fuel cell includes an anode, a cathode and an electrolyte. However, unlike batteries, fuel cells/cells cannot store electrical energy, do not discharge, and do not require electricity to be recharged. Fuel cells/cells can continuously generate electricity as long as they have a supply of fuel and air.

Unlike other power generators such as internal combustion engines or turbines powered by gas, coal, oil, etc., fuel cells/cells do not burn fuel. This means no noisy high pressure rotors, no loud exhaust noise, no vibration. Fuel cells/cells generate electricity through a silent electrochemical reaction. Another feature of fuel cells/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 nitrous oxide. The only products emitted during operation 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 fuel. Fuel cells/cells are assembled into assemblies and then into individual functional modules.

History of fuel cell/cell development

In the 1950s and 1960s, one of the biggest challenges for fuel cells was born out of the National Aeronautics and Space Administration's (NASA) need for energy sources for long-duration space missions. The NASA Alkaline Fuel Cell/Cell uses hydrogen and oxygen as fuel by combining the two chemical element in an electrochemical reaction. The output is three by-products of the reaction useful in space flight - electricity to power spacecraft, water for drinking and cooling systems and heat to keep the astronauts warm.

The discovery of fuel cells refers to early XIX century. The first evidence of the effect of fuel cells was obtained in 1838.

In the late 1930s, work began on alkaline fuel cells, and by 1939 a cell using high pressure nickel-plated electrodes had been built. During the Second World War, fuel cells/cells for British Navy submarines were developed and in 1958 a fuel assembly consisting of alkaline fuel cells/cells just over 25 cm in diameter was introduced.

Interest increased in the 1950s and 1960s and also in the 1980s when the industrial world experienced a shortage of fuel oil. In the same period, world countries also became concerned about the problem of air pollution and considered ways to generate environmentally friendly electricity. At present, fuel cell/cell technology is undergoing rapid development.

How fuel cells/cells work

Fuel cells/cells generate electricity and heat through an ongoing electrochemical reaction using an electrolyte, a cathode and an anode.

The anode and cathode are separated by an electrolyte that conducts protons. After hydrogen enters the anode and oxygen enters the cathode, a chemical reaction begins, as a result of which electric current, heat and water are generated.

On the anode catalyst, molecular hydrogen dissociates and loses electrons. Hydrogen ions (protons) are conducted through the electrolyte to the cathode, while electrons are passed through the electrolyte and through an external electrical circuit, creating a direct current that can be used to power equipment. On the cathode catalyst, an oxygen molecule combines with an electron (which is supplied from external communications) and an incoming proton, and forms water, which is the only reaction product (in the form of vapor and / or liquid).

Below is the corresponding reaction:

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

Types and variety of fuel cells/cells

Just like there are different types of internal combustion engines, there are different types of fuel cells - the choice of the appropriate type of fuel cell depends on its 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 "internally convert" the fuel at elevated temperatures, which means there is no need to invest in hydrogen infrastructure.

Fuel cells/cells on molten carbonate (MCFC)

Molten carbonate electrolyte fuel cells are high temperature fuel cells. The high operating temperature allows direct use of natural gas without a fuel processor and low calorific value fuel gas from process fuels and other sources.

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

When heated to a temperature of 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 sent through an external electrical circuit back to the cathode, generating electrical current and heat as a by-product.

Anode reaction: CO 3 2- + H 2 => H 2 O + CO 2 + 2e -
Reaction at the cathode: CO 2 + 1/2O 2 + 2e - => CO 3 2-
General element reaction: H 2 (g) + 1/2O 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, the natural gas is internally reformed, eliminating the need for a fuel processor. In addition, the advantages include the ability to use standard materials of construction, such as stainless steel sheet and nickel catalyst on the electrodes. The waste heat can be used to generate high pressure steam for various industrial and commercial purposes.

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

Molten carbonate fuel cells are suitable for use in large stationary installations. Industrially produced thermal power plants with output electric power 3.0 MW. Plants with an output power of up to 110 MW are being developed.

Fuel cells/cells based on phosphoric acid (PFC)

Fuel cells based on phosphoric (orthophosphoric) acid were the first fuel cells for commercial use.

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

The charge carrier in fuel cells of this type is hydrogen (H+, proton). A similar process occurs in proton exchange membrane fuel cells, in which hydrogen supplied to the anode is split into protons and electrons. The protons pass through the electrolyte and combine with oxygen from the air at the cathode to form water. The electrons are directed along an external electrical circuit, and an electric current is generated. 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 - \u003d\u003e 2 H 2 O
General element reaction: 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. In the combined production of heat and electricity, the overall efficiency is about 85%. In addition, given operating temperatures, 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 at a concentration of about 1.5%, which greatly 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 construction, 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 500 kW are industrially produced. Installations for 11 MW have passed the relevant tests. Plants with an output power of up to 100 MW are being developed.

Solid oxide fuel cells/cells (SOFC)

Solid oxide fuel cells are the fuel cells with the highest operating temperature. The operating temperature can vary from 600°C to 1000°C, which allows the use of various types of fuel 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 (O 2-) ions.

A solid electrolyte provides a hermetic gas transition from one electrode to another, while liquid electrolytes are located in a porous substrate. The charge carrier in fuel cells of this type is the oxygen ion (O 2-). At the cathode, oxygen molecules are separated from the air into an oxygen ion and four electrons. Oxygen ions pass through the electrolyte and combine with hydrogen to form four free electrons. Electrons are directed 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 - \u003d\u003e 2O 2-
General element reaction: 2H 2 + O 2 => 2H 2 O

The efficiency of the generated electrical energy is the highest of all fuel cells - about 60-70%. High operating temperatures allow for combined heat and power generation to generate high pressure steam. Combining a high temperature fuel cell with a turbine creates a hybrid fuel cell to increase the efficiency of electrical power generation up to 75%.

Solid oxide fuel cells operate at very high temperatures (600°C–1000°C), resulting in a long time to reach optimal operating conditions, and the system is slower to respond to changes in power consumption. At such high operating temperatures, no converter is required to recover hydrogen from the fuel, allowing the thermal power plant to operate with relatively impure fuels from coal gasification or waste gases, and the like. Also, this fuel cell is excellent for high power applications, including industrial and large central power plants. Industrially produced modules with an output electrical power of 100 kW.

Fuel cells/cells with direct methanol oxidation (DOMTE)

The technology of using fuel cells with direct oxidation of methanol 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 application of these elements is aimed at.

The structure of fuel cells with direct oxidation of methanol is similar to fuel cells with a proton exchange membrane (MOFEC), 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, releasing CO 2 , hydrogen ions and electrons, which are guided through an external electrical circuit, and an electric current is generated. Hydrogen ions pass through the electrolyte and react 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: 3/2O 2 + 6 H + + 6e - => 3H 2 O
General element reaction: CH 3 OH + 3/2O 2 => CO 2 + 2H 2 O

The advantage of this type of fuel cells is their small dimensions, due to the use of liquid fuel, and the absence of the need to use a converter.

Alkaline fuel cells/cells (AFC)

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, i.e. an aqueous solution of potassium hydroxide, contained in a porous, stabilized matrix. The concentration of potassium hydroxide may vary depending on the operating temperature of the fuel cell, which ranges from 65°C to 220°C. The charge carrier in an SFC is a hydroxide ion (OH-) moving from the cathode to the anode where it reacts with hydrogen to produce water and electrons. The water produced at the anode moves back to the cathode, again generating hydroxide ions there. As a result of this series of reactions taking place in the fuel cell, electricity is produced 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 - => 4 OH -
General reaction of the system: 2H 2 + O 2 => 2H 2 O

The advantage of SFCs is that these fuel cells are the cheapest to produce, since the catalyst needed on the electrodes can be any of the substances that are cheaper than those used as catalysts for other fuel cells. SHFCs operate at relatively low temperatures and are among the most efficient fuel cells - such characteristics can respectively contribute to faster power generation and high fuel efficiency.

One of characteristic features SHTE - high sensitivity to CO 2 that may 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 SFCs 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 CH4, which are safe for other fuel cells and even fuel for some of them, are detrimental to SFCs.

Polymer electrolyte fuel cells/cells (PETE)

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

Solid acid fuel cells/cells (SCFC)

In solid acid fuel cells, the electrolyte (CsHSO 4 ) does not contain water. The operating temperature is therefore 100-300°C. The rotation of the SO 4 2- oxy anions 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 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 numerous contacts between the fuel (or oxygen at the other end of the cell), electrolyte and electrodes.

Various fuel cell modules. fuel cell battery

1. Fuel Cell Battery
2. Other equipment operating under high temperature(integrated steam generator, combustion chamber, heat balance changer)
3. Heat resistant insulation

fuel cell module

Comparative analysis of types and varieties of fuel cells

Innovative energy-saving municipal heat and power plants are typically built on solid oxide fuel cells (SOFCs), polymer electrolyte fuel cells (PEFCs), phosphoric acid fuel cells (PCFCs), proton exchange membrane fuel cells (MPFCs) and alkaline fuel cells (APFCs) . They usually have the following characteristics:

Solid oxide fuel cells (SOFC) should be recognized as the most suitable, which:

• operate at a higher temperature, which reduces the need for expensive precious metals (such as platinum)
• can work for various types hydrocarbon fuels, mainly natural gas
• have a longer start-up time and therefore are better suited for long-term operation
• demonstrate high efficiency of power generation (up to 70%)
• due to high operating temperatures, the units can be combined with heat recovery systems, bringing the overall system efficiency up to 85%
• have near-zero emissions, operate silently and have low operating requirements compared to existing power generation technologies

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
SHTE	50–200°C	40-70%	pure hydrogen	space research
PETE	30-100°C	35-50%	pure hydrogen	Small installations

Since small thermal power plants can be connected to a conventional gas supply network, fuel cells do not require a separate hydrogen supply system. When using small thermal power plants based on solid oxide fuel cells, the generated heat can be integrated into heat exchangers for heating water and ventilation air, increasing the overall efficiency of the system. This innovative technology is best suited for efficient power generation without the need for expensive infrastructure and complex instrument integration.

Fuel cell/cell applications

Application of fuel cells/cells in telecommunication systems

With the rapid spread of wireless communication systems around the world, and the growing social and economic benefits of mobile phone technology, the need for reliable and cost-effective backup power has become critical. Grid losses throughout the year due to bad weather, natural disasters or limited grid capacity represent a permanent difficult problem for network operators.

Traditional telecom power backup solutions include batteries (lead-acid cell battery valve regulated) for short-term backup power and diesel and propane generators for longer backup power. Batteries are a relatively cheap source of backup power for 1 to 2 hours. However, batteries are not suitable for longer backup periods because they are expensive to maintain, become unreliable after long periods of use, are sensitive to temperatures, and are hazardous to life. environment after disposal. Diesel and propane generators can provide continuous backup power. However, generators can be unreliable, require extensive maintenance, and release high levels of pollutants and greenhouse gases into the atmosphere.

In order to remove the limitations of traditional backup power solutions, an innovative green fuel cell technology has been developed. Fuel cells are reliable, quiet, contain fewer moving parts than a generator, have a wider operating temperature range than a battery from -40°C to +50°C and, as a result, provide extremely high levels of energy savings. In addition, the lifetime cost of such a plant is lower than that of a generator. Lower fuel cell costs are the result of only one maintenance visit per year and significantly higher plant productivity. After all, the fuel cell is an environmentally friendly technology solution with minimal environmental impact.

Fuel cell units provide backup power for critical communications network infrastructures for wireless, permanent and broadband communications in a telecommunications system, ranging from 250W to 15kW, they offer many unrivaled innovative features:

• RELIABILITY– Few moving parts and no standby discharge
• ENERGY SAVING
• SILENCE– low noise level
• STABILITY– operating range from -40°C to +50°C
• ADAPTABILITY– outdoor and indoor installation (container/protective container)
• HIGH POWER– up to 15 kW
• LOW MAINTENANCE NEED– minimum annual maintenance
• ECONOMY- attractive total cost of ownership
• CLEAN ENERGY– low emissions with minimal environmental impact

The system senses the DC bus voltage at all times and smoothly accepts critical loads if the DC bus voltage drops below a user-defined setpoint. The system runs on hydrogen, which enters the fuel cell stack in one of two ways - either from a commercial source of hydrogen, or from a liquid fuel of methanol and water, using an on-board reformer system.

Electricity is produced by the fuel cell stack in the form of direct current. The DC power is sent to a converter that converts the unregulated DC power from the fuel cell stack into high quality, regulated DC power for the required loads. A fuel cell installation can provide backup power for many days, as the duration is limited only by the amount of hydrogen or methanol/water fuel available in stock.

Fuel cells offer high levels of energy savings, increased system reliability, more predictable performance in a wide range of climates, and reliable service life compared to industry standard valve regulated lead acid battery packs. Lifecycle costs are also lower due to significantly less maintenance and replacement requirements. Fuel cells offer end user environmental benefits as disposal costs and liability risks associated with lead acid cells are a growing concern.

The performance of electric batteries can be adversely affected by a wide range of factors such as charge level, temperature, cycles, lifespan and other variables. The energy provided will vary depending on these factors and is not easy to predict. The performance of a proton exchange membrane fuel cell (PEMFC) is relatively unaffected by these factors and can provide critical power as long as fuel is available. Increased predictability is an important benefit when moving to fuel cells for mission-critical backup power applications.

Fuel cells generate energy only when fuel is supplied, like a gas turbine generator, but do not have moving parts in the generation zone. Therefore, unlike a generator, they are not subject to rapid wear and do not require constant maintenance and lubrication.

The fuel used to drive the Extended Duration Fuel Converter is a mixture of methanol and water. Methanol is widely available, produced in industrial scale fuel, which currently has many applications, among others windshield washers, plastic bottles, engine additives, emulsion paints. Methanol is easy to transport, miscible with water, has good biodegradability and is sulfur free. It has a low freezing point (-71°C) and does not decompose during long storage.

Application of fuel cells/cells in communication networks

Security networks require reliable backup power solutions that can last for hours or days in an emergency if the power grid becomes unavailable.

With few moving parts and no standby power reduction, the innovative fuel cell technology offers an attractive solution compared to current backup power systems.

The most compelling reason for using fuel cell technology in communications networks is the increased overall reliability and security. During events such as power outages, earthquakes, storms, and hurricanes, it is important that systems continue to operate and have a reliable backup power supply for an extended period of time, regardless of the temperature or age of the backup power system.

The range of fuel cell power supplies is ideal for supporting secure communications networks. Thanks to their energy saving design principles, they provide an environmentally friendly, reliable backup power with extended duration (up to several days) for use in the power range from 250 W to 15 kW.

Application of fuel cells/cells in data networks

Reliable power supply for data networks, such as high-speed data networks and fiber optic backbones, is of key importance throughout the world. Information transmitted over such networks contains critical data for institutions such as banks, airlines or medical centers. A power outage in such networks not only poses a danger to the transmitted information, but also, as a rule, leads to significant financial losses. Reliable, innovative fuel cell installations that provide standby power provide the reliability you need to ensure uninterrupted power.

Fuel cell units operating on a liquid fuel mixture of methanol and water provide a reliable backup power supply with extended duration, up to several days. In addition, these units feature significantly reduced maintenance requirements compared to generators and batteries, requiring only one maintenance visit per year.

Typical application characteristics for the use of fuel cell installations in data networks:

• Applications with power inputs from 100 W to 15 kW
• Applications with battery life requirements > 4 hours
• Repeaters in fiber optic systems (hierarchy of synchronous digital systems, high speed internet, voice over IP…)
• Network nodes of high-speed data transmission
• WiMAX Transmission Nodes

Fuel cell standby installations offer numerous advantages for critical data network infrastructures over traditional battery or diesel generators, allowing for increased on-site utilization:

1. Liquid fuel technology solves the problem of hydrogen storage and provides virtually unlimited backup power.
2. Thanks to their quiet operation, low weight, resistance to temperature extremes and virtually vibration-free operation, fuel cells can be installed outdoors, in industrial buildings/containers or on rooftops.
3. On-site preparations for using the system are quick and economical, and the cost of operation is low.
4. The fuel is biodegradable and represents an environmentally friendly solution for the urban environment.

Application of fuel cells/cells in security systems

The most carefully designed building security and communication systems are only as reliable as the power that powers them. While most systems include some type of back-up uninterruptible power system for short-term power losses, they do not provide for the longer power outages that can occur after natural disasters or terrorist attacks. It can get critical important issue for many corporate and government agencies.

Vital systems such as CCTV monitoring and access control systems (ID card readers, door closing devices, biometric identification technology, etc.), automatic fire alarm and fire extinguishing systems, elevator control systems and telecommunication networks, exposed to risk in the absence of reliable alternative source continuous power supply.

Diesel generators are noisy, hard to locate, and are well aware of their reliability and maintenance issues. In contrast, a fuel cell standby installation is quiet, reliable, has zero or very low emissions, and is easy to install on a rooftop or outside a building. It does not discharge or lose power in standby mode. It ensures the continued operation of critical systems, even after the institution ceases operations and the building is abandoned by people.

Innovative fuel cell installations protect expensive investments in critical applications. They provide an environmentally friendly, reliable, long-lasting backup power (up to many days) for use in the power range from 250 W to 15 kW, combined with numerous unsurpassed features and, especially, high level energy saving.

Fuel cell backup power plants offer numerous advantages for critical applications such as security and building management systems over traditional battery or diesel generators. Liquid fuel technology solves the problem of hydrogen storage and provides virtually unlimited backup power.

Application of fuel cells/cells in domestic heating and power generation

Solid oxide fuel cells (SOFCs) are used to build reliable, energy efficient and harmful emissions thermal power plants for the generation of electricity and heat from widely available natural gas and renewable fuel sources. These innovative units are used in a wide variety of markets, from domestic power generation to power supply to remote areas, as well as auxiliary power sources.

Application of fuel cells/cells in distribution networks

Small thermal power plants are designed to operate in a distributed power generation network, consisting of a large number small generator sets instead of one centralized power plant.

The figure below shows the loss in power generation efficiency when it is generated in a CHP plant and transmitted to homes through traditional transmission networks used in this moment. Efficiency losses in district generation include losses from the power plant, low and high voltage transmission, and distribution losses.

The figure shows the results of the integration of small thermal power plants: electricity is generated with a generation efficiency of up to 60% at the point of use. In addition, the household can use the heat generated by the fuel cells for water and space heating, which increases the overall efficiency of fuel energy processing and improves energy savings.

Using Fuel Cells to Protect the Environment - Utilization of Associated Petroleum Gas

One of the most important tasks in the oil industry is the utilization of associated petroleum gas. The existing methods of utilization of associated petroleum gas have a lot of disadvantages, the main one being that they are not economically viable. Associated petroleum gas is flared, which causes great harm to the environment and human health.

Innovative fuel cell heat and power plants using associated petroleum gas as a fuel open the way to a radical and cost-effective solution to the problems of associated petroleum gas utilization.

1. One of the main advantages of fuel cell installations is that they can operate reliably and sustainably on variable composition associated petroleum gas. Due to the flameless chemical reaction underlying the operation of a fuel cell, a reduction in the percentage of, for example, methane only causes a corresponding reduction in power output.
2. Flexibility in relation to the electrical load of consumers, differential, load surge.
3. For the installation and connection of thermal power plants on fuel cells, their implementation does not require capital expenditures, because The units are easily mounted on unprepared sites near fields, are easy to operate, reliable and efficient.
4. High automation and modern remote control do not require the constant presence of personnel at the plant.
5. Simplicity and technical perfection of the design: the absence of moving parts, friction, lubrication systems provides significant economic benefits from the operation of fuel cell installations.
6. Water consumption: none at ambient temperatures up to +30 °C and negligible at higher temperatures.
7. Water outlet: none.
8. In addition, fuel cell thermal power plants do not make noise, do not vibrate, do not emit harmful emissions into the atmosphere