Introducing sustainable technologies: fuel cells. fuel cells

Benefits of fuel cells/cells

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 recharge. Fuel cells/cells can continuously generate electricity as long as they have a supply of fuel and air.

Unlike other power generators such as motors internal combustion or turbines running on 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 US National Aeronautics and Space Administration's (NASA) need for energy sources for long-duration space missions. NASA's Alkaline Fuel Cell/Cell uses hydrogen and oxygen as fuel, combining the two in an electrochemical reaction. The output is three by-products of the reaction useful in spaceflight - electricity to power the spacecraft, water for drinking and cooling systems, and heat to keep the astronauts warm.

The discovery of fuel cells dates back to the beginning of the 19th 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 industrial world experienced a shortage of petroleum fuel. 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.

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 suitable type 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. High operating temperature allows direct use of natural gas without a fuel processor and low calorific value fuel gas production processes and from 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 high degree 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 applications.

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. Thermal power plants with an output electric power of 3.0 MW are industrially produced. 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 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 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 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 size, 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. SCFCs 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 the characteristic features of SHTE 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 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

Fuel Cell Battery
Other high temperature equipment (integrated steam generator, combustion chamber, heat balance changer)
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 operate on various types of hydrocarbon fuels, mainly on natural gas
have more time starting and are therefore better suited for long-term
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 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, as well as 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 are a constant challenge for grid operators.

Traditional telecom power backup solutions include batteries (valve-regulated lead-acid battery cell) 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 eliminate 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 technological solution with minimal impact on the environment.

Fuel cell units provide backup power to critical communications network infrastructures for wireless, permanent and broadband in the telecommunications system, ranging from 250W to 15kW, they offer many unsurpassed 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 all the time 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 superior energy efficiency, 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 the 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, life 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 a widely available, commercially produced fuel that currently has many applications, including windshield washer, 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 currently available 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. Power failure in such networks not only poses a danger to 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 requirements for battery life> 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:

Liquid fuel technology solves the problem of hydrogen storage and provides virtually unlimited backup power.
Due to their quiet operation, low weight, resistance to temperature extremes and virtually vibration-free operation, fuel cells can be installed outdoors, in industrial premises/containers or on rooftops.
On-site preparations for using the system are quick and economical, and the cost of operation is low.
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. This could be a critical 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, are at risk in the absence of a reliable alternative source of continuous power supply.

Diesel generators are noisy, difficult to locate, and are well known for their reliability and maintenance. In contrast, a fuel cell back-up 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 environmentally friendly, reliable backup power with extended duration (up to many days) for use in the power range from 250 W to 15 kW, combined with numerous unsurpassed features and, especially, a high level of energy saving.

Fuel cell power backup units offer numerous advantages for mission 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 emission-free thermal power plants to generate 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 of 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.

One of the main advantages of fuel cell installations is that they can operate reliably and sustainably on associated petroleum gas variable composition. 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.
Flexibility in relation to the electrical load of consumers, differential, load surge.
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.
High automation and modern remote control do not require the constant presence of personnel at the plant.
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.
Water consumption: none at ambient temperatures up to +30 °C and negligible at higher temperatures.
Water outlet: none.
In addition, fuel cell thermal power plants do not make noise, do not vibrate, do not emit harmful emissions into the atmosphere

They are operated by spacecraft from the US National Aeronautics and Space Administration (NASA). They provide power 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 a combustion process - by chemical means, much like batteries. The only difference is that they use other chemicals, hydrogen and oxygen, and the product of the chemical reaction is water. Natural gas can also be used but, of course, a certain level of carbon dioxide emissions is unavoidable when using hydrocarbon fuels.

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

The history of development

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

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

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

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

How a fuel cell works

Fuel cells are like 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 it can be said that the efficiency of an internal combustion engine is rather low. For example, it is expected that the efficiency of fuel cells when used in a vehicle - a project currently under development - will be more than twice as efficient as today's typical gasoline engines used in cars.

Although both batteries and fuel cells generate electricity chemically, they perform two very different functions. Batteries are stored energy devices: the electricity they generate is the result of a chemical reaction of matter already inside them. Fuel cells do not store energy, but convert some of the energy from an 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 deposited 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). Each electrode has a different chemical reaction.

At the anode, hydrogen breaks down 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 promotes the dissociation reaction:

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

H2 = diatomic hydrogen molecule, form, in

in which hydrogen is present as 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 (toward the cathode), but electrons do not. The electrons move towards the cathode along the outer conducting circuit. This movement of electrons is an electrical current that can be used to power an external device connected to the 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 the external load) "recombine" and react with the oxygen supplied to the cathode to form water, H2O:

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

The overall reaction in the fuel cell is written as:

2H2 + O2 ==> 2H2O.

In their work, fuel cells use hydrogen fuel and oxygen from the air. Hydrogen can be supplied directly or by separating it from an external fuel source such as natural gas, gasoline or methanol. In the case of an external source, it must be chemically converted to extract the hydrogen. This process is called "reforming". Hydrogen can also be obtained from ammonia, alternative resources such as gas from city landfills and from gas treatment plants. Wastewater, as well as by electrolysis of water, in which electricity is used to decompose water into hydrogen and oxygen. Currently, most of the fuel cell technologies used in transportation 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 plant inside a gasoline reformer to supply hydrogen to a self-contained fuel cell. Researchers at the Pacific Northwest National Laboratory in the US have demonstrated a compact fuel reformer that is one-tenth the size of a power pack. US utility, Northwest Power Systems, and Sandia National Laboratory have demonstrated a fuel reformer that converts diesel fuel to hydrogen for fuel cells.

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

Applications

Fuel cells can be used in both stationary and mobile devices. In response to tightening U.S. emissions regulations, automakers 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 roads in 2004 or 2005.

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

Fixed installations using fuel cell technology are also being demonstrated, but they are not yet widely used. commercial application. The First National Bank of Omaha in Nebraska uses a fuel cell system to power the computers because the system is more reliable than the old mains system with battery backup. The largest in the world commercial system a 1.2 MW fuel cell will soon be installed at a mail center in Alaska. Fuel cell laptops, control systems used in sewage treatment plants and vending machines are also being tested and demonstrated.

"Pros and cons"

Fuel cells have a number of advantages. While the efficiency of modern internal combustion engines is only 12-15%, for fuel cells this coefficient is 50%. The efficiency of fuel cells can remain at quite high level, even when they are not used at full rated power, which is a major advantage over petrol engines.

The modular nature of the fuel cell design means that the capacity of a fuel cell power plant can be increased by simply adding a few more stages. This ensures that the capacity underutilization factor is minimized, allowing better matching of supply and demand. Because the efficiency of a fuel cell stack is determined by the performance of the individual cells, small fuel cell power plants operate just as efficiently as large ones. In addition, waste heat from stationary fuel cell systems can be used for water and space heating, 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 formed as by-products. So on spacecraft, astronauts drink water, which is formed as a result of the operation of onboard fuel cells. The composition of emissions depends on the nature of the hydrogen source. The use of methanol results in zero emissions of nitrogen oxides and carbon monoxide and only small hydrocarbon emissions. Emissions increase as you move from hydrogen to methanol to gasoline, although even with gasoline, emissions will remain quite low. In any case, the replacement of today's traditional internal combustion engines with fuel cells would result in an overall reduction in CO2 and NOx emissions.

The use of fuel cells provides the flexibility of the energy infrastructure, creating additional features for decentralized power generation. The multiplicity of decentralized energy sources makes it possible to reduce transmission losses and develop energy sales markets (which is especially important for remote and rural areas with no 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 High Quality and increased reliability. They are durable, have no moving parts, and produce a constant amount of power.

However, fuel cell technology needs to be further improved in order to improve 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 components. technological characteristics including capital operating costs, pollutant emissions, power quality, durability, decommissioning and flexibility.

Although hydrogen gas is the best fuel, the infrastructure or transport 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 each vehicle to be fitted with a fossil fuel-to-hydrogen converter ("reformer"). The disadvantage of this approach is that it uses fossil fuels and thus results in carbon dioxide emissions. Methanol, currently the leading candidate, creates fewer emissions than gasoline, but it would require a larger capacity tank in a car because it takes up twice as much 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 thus In this way, emissions of harmful substances, which are observed when using methanol or gasoline fuel cells, could be avoided. The hydrogen could be stored and converted to electricity in the fuel cell as needed. Going forward, connecting fuel cells to these kinds of renewable energy sources is likely to be an effective strategy to provide a productive, environmentally friendly and versatile source of energy.

IEER's recommendations are for local, state, and state governments to allocate a portion of their transportation procurement budgets to fuel cell vehicles and stationary fuel cell systems to provide heat and electricity to some of their essential or new buildings. This will contribute to the development of vital technology and reduce greenhouse gas emissions.

AT modern life chemical current sources surround us everywhere: these are batteries in flashlights, batteries in mobile phones, hydrogen fuel cells that are already being used in some vehicles. The rapid development of electrochemical technologies can lead to the fact that in the near future, instead of cars with gasoline engines, we will be surrounded only by electric vehicles, phones will no longer run out quickly, and each house will have its own fuel cell electric generator. One of the joint programs of the Ural Federal University with the Institute of High-Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences, in partnership with which we publish this article, is devoted to increasing the efficiency of electrochemical storage and power generators.

Today, there are many different types of batteries, among which it is increasingly difficult to navigate. It is far from clear to everyone how a battery differs from a supercapacitor and why a hydrogen fuel cell can be used without fear of harming the environment. In this article, we will talk about how chemical reactions are used to generate electricity, what is the difference between the main types of modern chemical current sources, and what prospects open up for electrochemical energy.

Chemistry as a source of electricity

First, let's look at why chemical energy can be used to generate electricity at all. The thing is that in redox reactions, electrons are transferred between two different ions. If the two halves of the chemical reaction are separated in space so that oxidation and reduction take place separately from each other, then it is possible to make sure that an electron that breaks away from one ion does not immediately fall on the second, but first goes along a path predetermined for it. This reaction can be used as a source of electric current.

This concept was first implemented in the 18th century by the Italian physiologist Luigi Galvani. The action of a traditional galvanic cell is based on the reactions of reduction and oxidation of metals with different activity. For example, a classical cell is a galvanic cell in which zinc is oxidized and copper is reduced. The reduction and oxidation reactions take place, respectively, at the cathode and anode. And so that copper and zinc ions do not fall into "foreign territory", where they can react with each other directly, a special membrane is usually placed between the anode and cathode. As a result, a potential difference arises between the electrodes. If you connect the electrodes, for example, with a light bulb, then current begins to flow in the resulting electrical circuit and the light bulb lights up.

Diagram of a galvanic cell

Wikimedia Commons

In addition to the materials of the anode and cathode, an important component of the chemical current source is the electrolyte, inside which ions move and on the border of which all electrochemical reactions proceed with the electrodes. In this case, the electrolyte does not have to be liquid - it can be both a polymer and a ceramic material.

The main disadvantage of a galvanic cell is its limited operating time. As soon as the reaction goes to the end (that is, the entire gradually dissolving anode is completely consumed), such an element will simply stop working.

Finger alkaline batteries

Rechargeable

The first step towards expanding the capabilities of chemical current sources was the creation of a battery - a current source that can be recharged and therefore reused. To do this, scientists simply proposed to use reversible chemical reactions. Having completely discharged the battery for the first time, with the help of an external current source, the reaction that has taken place in it can be started in the opposite direction. This will restore the original state so that the battery can be used again after recharging.

Automotive Lead Acid Battery

To date, many different types of batteries have been created, which differ in the type of chemical reaction taking place in them. The most common types of batteries are lead-acid (or simply lead) batteries, which are based on the oxidation-reduction reaction of lead. Such devices have a fairly long service life, and their energy consumption is up to 60 watt-hours per kilogram. Even more popular recently are lithium-ion batteries based on the lithium redox reaction. The energy intensity of modern lithium-ion batteries now exceeds 250 watt-hours per kilogram.

Li-ion battery for mobile phone

The main problems of lithium-ion batteries are their low efficiency at low temperatures, rapid aging and increased explosiveness. And due to the fact that lithium metal reacts very actively with water to form hydrogen gas and oxygen is released when the battery burns, spontaneous combustion of a lithium-ion battery is very difficult to use with traditional fire extinguishing methods. In order to improve the safety of such a battery and speed up its charging time, scientists propose a cathode material that prevents the formation of dendritic lithium structures, and add substances to the electrolyte that form explosive structures, and components that ignite in the early stages.

Solid electrolyte

As another less obvious way to improve the efficiency and safety of batteries, chemists have proposed not to limit themselves to liquid electrolytes in chemical power sources, but to create an entirely solid state power source. In such devices, there are no liquid components at all, but there is a layered structure of a solid anode, a solid cathode, and a solid electrolyte between them. The electrolyte at the same time performs the function of the membrane. Charge carriers in a solid electrolyte can be various ions, depending on its composition and the reactions that take place on the anode and cathode. But they are always small enough ions that can move relatively freely through the crystal, for example, H + protons, Li + lithium ions, or O 2- oxygen ions.

Hydrogen fuel cells

The ability to recharge and special security measures make batteries a much more promising source of current than conventional batteries, but still, each battery contains a limited amount of reagents inside, and therefore a limited supply of energy, and each time the battery must be recharged to resume its performance.

To make a battery “infinite”, it is possible to use as an energy source not those substances that are inside the cell, but fuel specially pumped through it. Best of all, a substance that is as simple as possible in composition, environmentally friendly and available in abundance on Earth is best suited as such a fuel.

The most suitable substance of this type is hydrogen gas. Its oxidation with atmospheric oxygen to form water (according to the reaction 2H 2 + O 2 → 2H 2 O) is a simple redox reaction, and electron transport between ions can also be used as a current source. The reaction proceeding in this case is a kind of reverse reaction to the water electrolysis reaction (in which, under the action of an electric current, water decomposes into oxygen and hydrogen), and for the first time such a scheme was proposed back in the middle of the 19th century.

But despite the fact that the circuit looks quite simple, creating an efficient device based on this principle is not at all a trivial task. To do this, it is necessary to separate the flows of oxygen and hydrogen in space, ensure the transport of the necessary ions through the electrolyte, and reduce possible energy losses at all stages of operation.

Schematic diagram of the operation of a hydrogen fuel cell

The scheme of a working hydrogen fuel cell is very similar to the scheme of a chemical current source, but contains additional channels for supplying fuel and oxidizer and removing reaction products and excess supplied gases. The electrodes in such an element are porous conductive catalysts. Gaseous fuel (hydrogen) is supplied to the anode, and an oxidizing agent (oxygen from the air) is supplied to the cathode, and at the boundary of each of the electrodes with the electrolyte, its own half-reaction takes place (oxidation of hydrogen and reduction of oxygen, respectively). In this case, depending on the type of fuel cell and the type of electrolyte, the formation of water itself can proceed either in the anode or cathode space.

Toyota hydrogen fuel cell

Joseph Brent / flickr

If the electrolyte is a proton-conducting polymer or ceramic membrane, an acid or alkali solution, then the charge carrier in the electrolyte is hydrogen ions. In this case, molecular hydrogen is oxidized at the anode to hydrogen ions, which pass through the electrolyte and react with oxygen there. If the oxygen ion O 2– is the charge carrier, as in the case of a solid oxide electrolyte, then oxygen is reduced to an ion at the cathode, this ion passes through the electrolyte and oxidizes hydrogen at the anode to form water and free electrons.

In addition to the hydrogen oxidation reaction for fuel cells, it was proposed to use other types of reactions. For example, instead of hydrogen, the reducing fuel could be methanol, which is oxidized by oxygen to carbon dioxide and water.

Fuel Cell Efficiency

Despite all the advantages of hydrogen fuel cells (such as environmental friendliness, virtually unlimited efficiency, compact size and high energy intensity), they also have a number of disadvantages. These include, first of all, the gradual aging of the components and the difficulties in storing hydrogen. It is on how to eliminate these shortcomings that scientists are working today.

It is currently proposed to increase the efficiency of fuel cells by changing the composition of the electrolyte, the properties of the catalyst electrode, and the geometry of the system (which ensures the supply of fuel gases to the desired point and reduces side effects). To solve the problem of storing hydrogen gas, materials containing platinum are used, for saturation of which, for example, graphene membranes.

As a result, it is possible to achieve an increase in the stability of the fuel cell and the lifetime of its individual components. Now the coefficient of conversion of chemical energy into electrical energy in such cells reaches 80 percent, and under certain conditions it can be even higher.

Huge prospects for hydrogen energy are associated with the possibility of combining fuel cells into whole batteries, turning them into electric generators with high power. Even now, electric generators operating on hydrogen fuel cells have a power of up to several hundred kilowatts and are used as power sources for vehicles.

Alternative electrochemical storage

In addition to classical electrochemical current sources, more unusual systems are also used as energy storage devices. One of these systems is a supercapacitor (or ionistor) - a device in which charge separation and accumulation occurs due to the formation of a double layer near a charged surface. At the electrode-electrolyte interface in such a device, ions of different signs line up in two layers, the so-called "double electric layer", forming a kind of very thin capacitor. The capacitance of such a capacitor, that is, the amount of accumulated charge, will be determined by the specific surface area of the electrode material; therefore, it is advantageous to take porous materials with the maximum specific surface area as a material for supercapacitors.

Ionistors are champions among charge-discharge chemical current sources in terms of charge rate, which is an undoubted advantage of this type of device. Unfortunately, they are also record holders in terms of discharge speed. The energy density of ionistors is eight times less compared to lead batteries and 25 times less than lithium-ion ones. Classic "double-layer" ionistors do not use an electrochemical reaction at their core, and the term "capacitor" is most accurately applied to them. However, in those versions of ionistors, which are based on an electrochemical reaction and charge accumulation extends into the depth of the electrode, it is possible to achieve higher discharge times while maintaining a fast charge rate. The efforts of developers of supercapacitors are aimed at creating hybrid devices with batteries that combine the advantages of supercapacitors, primarily a high charge rate, and the advantages of batteries - high energy intensity and long discharge time. Imagine in the near future a ionistor battery that will charge in a couple of minutes and power a laptop or smartphone for a day or more!

Despite the fact that now the energy density of supercapacitors is still several times less than the energy density of batteries, they are used in consumer electronics and for engines of various vehicles, including the most.

* * *

Thus, today there are a large number of electrochemical devices, each of which is promising for its specific applications. To improve the efficiency of these devices, scientists need to solve a number of problems, both fundamental and technological. Most of these tasks within the framework of one of the breakthrough projects are being dealt with at the Ural Federal University, therefore, we asked Maxim Ananiev, Director of the Institute of High-Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences, Professor of the Department of Electrochemical Production Technology of the Institute of Chemical Technology of the Ural Federal University, to talk about the immediate plans and prospects for the development of modern fuel cells. .

N+1: Is there an alternative to the most popular Li-Ion batteries in the near future?

Maxim Ananiev: Modern efforts of battery developers are aimed at replacing the type of charge carrier in the electrolyte from lithium to sodium, potassium, and aluminum. As a result of replacing lithium, it will be possible to reduce the cost of the battery, although the weight and size characteristics will proportionally increase. In other words, for the same electrical characteristics, a sodium-ion battery will be larger and heavier than a lithium-ion battery.

In addition, one of the promising developing areas for improving batteries is the creation of hybrid chemical energy sources based on the combination of metal-ion batteries with an air electrode, as in fuel cells. In general, the direction of creating hybrid systems, as has already been shown on the example of supercapacitors, apparently, in the near future will make it possible to see chemical energy sources with high consumer characteristics on the market.

Ural Federal University, together with academic and industrial partners from Russia and the world, is currently implementing six megaprojects that are focused on breakthrough areas scientific research. One of such projects is "Perspective Technologies of Electrochemical Energy Engineering from Chemical Design of New Materials to New Generation Electrochemical Devices for Energy Conservation and Conversion".

The group of scientists of the Strategic Academic Unit (SAU) UrFU School of Natural Sciences and Mathematics, which includes Maxim Ananiev, is engaged in the design and development of new materials and technologies, including fuel cells, electrolytic cells, metal graphene batteries, electrochemical power storage systems and supercapacitors.

Research and scientific work are conducted in constant cooperation with the Institute of High-Temperature Electrochemistry, Ural Branch of the Russian Academy of Sciences and with the support of partners.

Which fuel cells are currently being developed and have the greatest potential?

One of the most promising types of fuel cells are proton-ceramic cells. They have advantages over polymer fuel cells with a proton exchange membrane and solid oxide cells, as they can operate with a direct supply of hydrocarbon fuel. This significantly simplifies the design of a power plant based on proton-ceramic fuel cells and the control system, and therefore increases the reliability of operation. True, this type of fuel cells is historically less developed at the moment, but modern scientific research allows us to hope for a high potential of this technology in the future.

What problems related to fuel cells are being dealt with at the Ural Federal University now?

Now UrFU scientists, together with the Institute of High-Temperature Electrochemistry (IHTE) of the Ural Branch of the Russian Academy of Sciences, are working on the creation of highly efficient electrochemical devices and autonomous power generators for applications in distributed energy. The creation of power plants for distributed energy initially implies the development of hybrid systems based on an electric power generator and a storage device, which are batteries. At the same time, the fuel cell operates constantly, providing load during peak hours, and in idle mode it charges the battery, which itself can act as a reserve both in case of high power consumption and in case of emergency situations.

Chemists from Ural Federal University and IHTE achieved the greatest success in the development of solid-oxide and proton-ceramic fuel cells. Since 2016, in the Urals, together with the State Corporation Rosatom, the first Russian production of power plants based on solid oxide fuel cells has been created. The development of the Ural scientists has already passed "field" tests at the gas pipeline cathodic protection station at the experimental site of Uraltransgaz LLC. The power plant with a rated power of 1.5 kilowatts has worked for more than 10 thousand hours and has shown a high potential for the use of such devices.

Within the framework of the joint laboratory of Ural Federal University and IHTE, electrochemical devices based on a proton-conducting ceramic membrane are being developed. This will make it possible in the near future to reduce the operating temperatures for solid oxide fuel cells from 900 to 500 degrees Celsius and to abandon the preliminary reforming of hydrocarbon fuel, thus creating cost-effective electrochemical generators capable of operating under the conditions of a developed gas supply infrastructure in Russia.

Alexander Dubov

Ecology of knowledge. Science and technology: Hydrogen energy is one of the most highly efficient industries, and fuel cells allow it to remain at the forefront of innovative technologies.

A fuel 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. Again, like a battery, a fuel cell includes an anode, a cathode, and an electrolyte. However, unlike batteries, fuel cells cannot store electrical energy, do not discharge, and do not require electricity to be recharged. Fuel cells can continuously generate electricity as long as they have a supply of fuel and air. Correct term to describe a working fuel cell, it is a system of elements, since some auxiliary systems are required for full operation.

Unlike other power generators such as internal combustion engines or turbines powered by gas, coal, 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 nitrous oxide. The only products emitted 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 fuel. Fuel cells are assembled into assemblies and then into individual functional modules.

The principle of operation of fuel cells

Fuel cells generate electricity and heat due to the 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: 2H2 => 4H+ + 4e-
Reaction at the cathode: O2 + 4H+ + 4e- => 2H2O
General element reaction: 2H2 + O2 => 2H2O

Fuel cell types

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 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 elements 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. This process was developed in the mid-1960s. Since that time, manufacturing technology, performance and reliability have been improved.

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, the salts become a conductor for carbonate ions (CO32-). 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: CO32- + H2 => H2O + CO2 + 2e-
Reaction at the cathode: CO2 + 1/2O2 + 2e- => CO32-
General element reaction: H2(g) + 1/2O2(g) + CO2(cathode) => H2O(g) + CO2(anode)

Molten carbonate 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. Plants with an output power of up to 100 MW are being developed.

Fuel cells based on phosphoric acid (PFC).

Fuel cells based on phosphoric (orthophosphoric) acid 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, performance and cost have been increased.

Fuel cells based on phosphoric (orthophosphoric) acid use an electrolyte based on orthophosphoric acid (H3PO4) 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 (MEFCs), 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.

Anode reaction: 2H2 => 4H+ + 4e-
Reaction at the cathode: O2(g) + 4H+ + 4e- => 2H2O
General element reaction: 2H2 + O2 => 2H2O

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, CO2 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 400 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.

Fuel Cells with Proton Exchange Membrane (PME)

Proton exchange membrane fuel cells are considered the best type of fuel cells for vehicle power generation, which can replace gasoline and diesel internal combustion engines. These fuel cells were first used by NASA for the Gemini program. Today, installations on MOPFC with a power of 1 W 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 passes protons, but does not conduct electrons.

The fuel is hydrogen, and the charge carrier is a hydrogen ion (proton). At the anode, the hydrogen molecule is separated into a hydrogen ion (proton) and electrons. The hydrogen ions pass through the electrolyte to the cathode, while the 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:

Anode reaction: 2H2 + 4OH- => 4H2O + 4e-
Reaction at the cathode: O2 + 2H2O + 4e- => 4OH-
General element reaction: 2H2 + O2 => 2H2O

Compared to other types of fuel cells, proton exchange membrane fuel cells produce more power for a given fuel cell volume or weight. This feature allows them to be compact and lightweight. In addition, the operating temperature is less than 100°C, which allows you to quickly start 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 use in vehicles.

Another advantage is that the electrolyte is a solid rather than a liquid substance. Keeping the gases at the cathode and anode is easier with a solid electrolyte and therefore such fuel cells are cheaper to manufacture. Compared to other electrolytes, the use of a solid electrolyte does not cause problems such as orientation, there are fewer problems due to the occurrence of corrosion, which leads to a longer durability of the cell and its components.

Solid oxide fuel cells (SOFC)

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 (О2-). 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.

Anode reaction: 2H2 + 2O2- => 2H2O + 4e-
Reaction at the cathode: O2 + 4e- => 2O2-
General element reaction: 2H2 + O2 => 2H2O

The efficiency of the generated electrical energy is the highest of all fuel cells - about 60%. In addition, 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 by up to 70%.

Fuel cells with direct methanol oxidation (DOMTE)

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 (CH3OH) is oxidized in the presence of water at the anode, releasing CO2, 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.

Anode reaction: CH3OH + H2O => CO2 + 6H+ + 6e-
Reaction at the cathode: 3/2O2 + 6H+ + 6e- => 3H2O
General element reaction: CH3OH + 3/2O2 => CO2 + 2H2O

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

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

Alkaline fuel cells (AFC)

Alkaline fuel cells (ALFCs) are one of the most studied technologies and have been used since the mid-1960s. by NASA in the Apollo and Space Shuttle programs. On board 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, 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 the 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:

Anode reaction: 2H2 + 4OH- => 4H2O + 4e-
Reaction at the cathode: O2 + 2H2O + 4e- => 4OH-
General reaction of the system: 2H2 + O2 => 2H2O

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. In addition, SCFCs operate at a relatively low temperature and are among the most efficient fuel cells - such characteristics can respectively contribute to faster power generation and high fuel efficiency.

One of the characteristic features of SFC 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 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, H2O and CH4, which are safe for other fuel cells and even fuel for some of them, are detrimental to SFCs.

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 conduction of water ions H2O+ (proton, red) is 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 (SCFC)

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.published

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 units
SHTE	50–200°C	40-65%	pure hydrogen	space research
PETE	30-100°C	35-50%	pure hydrogen	Small installations

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

Fuel cells generate electricity quietly and efficiently without polluting the environment. Unlike fossil fuel energy sources, the by-products 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 hurdles researchers face in making fuel cells practical and affordable for consumers.

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

Another electrochemical device that we are all very familiar with is the battery. The battery has all the necessary chemical elements inside itself 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 fed into it so that it never "dies". Electricity will be generated for as long as there is a flow chemical substances into the element. Most fuel cells in use today use hydrogen and oxygen.

Hydrogen is the most common 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 expend energy in the form of heat or electricity.

Invention of fuel cells

Sir William Grove invented the first fuel cell in 1839. Grove knew that water could be split into hydrogen and oxygen by running an electric current through it (a process called electrolysis). He suggested that in the reverse order, electricity and water could be obtained. He created a primitive fuel cell and named it gas galvanic battery. After 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 power 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 batteries of all kinds. Internal combustion engines, like gas turbines, burn different kinds fuel and use the pressure created by the expansion of gases to perform mechanical work. Batteries convert chemical energy into electrical energy when needed. Fuel cells need to 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 using different chemical processes. Fuel cells are usually classified according to their operating temperature and typeelectrolyte, which they use. Some types of fuel cells are well suited for use in stationary power plants. Others may be useful for small portable devices or to power 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. PEMFC has both high power and relatively low operating temperature (in the range of 60 to 80 degrees Celsius). The low operating temperature means the fuel cells can quickly warm up to start generating electricity.

Solid oxide fuel cell (SOFC)

These fuel cells are most suitable for large stationary power generators that could provide electricity to factories or cities. This type of fuel cell operates at very high temperatures (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 operating life of any fuel cell under certain conditions. The high temperature also has the advantage that the steam generated by the fuel cells can be directed to turbines and generate more electricity. This process is called cogeneration of heat and electricity and improves overall system efficiency.

Alkaline fuel cell (AFC)

It is one of the oldest fuel cell designs, used since the 1960s. AFCs are very susceptible to pollution 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 for use 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 automotive use.

Methanol fuel cells Direct methanol fuel cell (DMFC)

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

Fuel cell with polymer exchange membrane

The polymer exchange membrane 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 that are released from hydrogen molecules, after which they can be used in an external circuit. It is engraved with channels through which hydrogen gas is distributed evenly over the surface of the catalyst.

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

3.Electrolyte-proton exchange membrane. It is a specially treated material that conducts only positively charged ions and blocks electrons. In PEMFC, the membrane must be hydrated 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 deposited very thinly on 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) entering under pressure 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 (performing useful work, such as motor rotation) and return 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 from the external circuitry to form a water molecule (H2O).

This reaction in a single fuel cell produces only approximately 0.7 volts. In order 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 oxidation with decreasing potential. The 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 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 subjected to high temperatures) in the form of a bipolar sheet material.

Fuel Cell Efficiency

Reducing pollution is one of the main goals of a fuel cell. By comparing a car powered by a fuel cell with a car powered by a gasoline engine and a car powered by a battery, you can 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 beneficial actions to the point where mechanical energy is produced. Let's start with the fuel cell car.

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 electrical energy 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 an overall efficiency of approximately 80*80/100=64 percent. Honda's FCX concept vehicle reportedly has a 60 percent energy efficiency.

If the fuel source is not in the form of pure hydrogen, then the vehicle will also need a reformer. Reformers convert hydrocarbon or alcohol fuels into hydrogen. They generate heat and produce CO and CO2 in addition to hydrogen. To purify the resulting hydrogen, they use various devices, but this cleaning is insufficient and reduces the efficiency of the fuel cell. Therefore, the researchers decided to focus on fuel cells for vehicles running on 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 car powered by gasoline is surprisingly low. All the heat that goes out in the form of 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 automobile gasoline engine is approximately 20 percent. Thus, only approximately 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 a fossil fuel combustion process (rather than nuclear, hydroelectric, solar or wind power), then only about 40 percent of the fuel consumed by the power plant was converted into electricity. Plus, the process of charging a car requires converting alternating current (AC) power to direct current (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 the power plant, and 90 percent for charging the car. This gives an overall efficiency of 26 percent. The overall efficiency varies considerably depending on which power station is used to charge the battery. If the electricity for a car is generated, for example, by a hydroelectric plant, then the efficiency of an electric car will be about 65 percent.

Scientists are researching and refining designs to continue improving fuel cell efficiency. One of the new approaches is to combine fuel cell and battery powered vehicles. A concept vehicle is being developed to be powered by a fuel cell powered hybrid powertrain. It uses a lithium battery to power the car while a fuel cell recharges the battery.

Fuel cell vehicles are potentially as efficient as a battery-powered car that is charged from a fossil fuel-free power plant. But the achievement of such a potential by practical and accessible way may prove 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 rise to 68%. Americans use two-thirds of the oil daily 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 all the oil produced in the world, although only 4.6% of the world's population lives here.

Experts expect oil prices to continue rising over the next few decades as cheaper sources run dry. Oil companies should develop oil fields in increasingly difficult conditions, causing oil prices to rise.

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

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

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

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

Clearly, scientists and manufacturers have a lot of work to do before fuel cells become an alternative. modern methods energy production. And yet, with the support of the whole world and global cooperation, a viable energy system based on fuel cells can become a reality in a couple of decades.

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History of fuel cell/cell development

How fuel cells/cells work

Types and variety of fuel cells/cells

Fuel cells/cells on molten carbonate (MCFC)

Fuel cells/cells based on phosphoric acid (PFC)

Solid oxide fuel cells/cells (SOFC)

Fuel cells/cells with direct methanol oxidation (DOMTE)

Alkaline fuel cells/cells (AFC)

Polymer electrolyte fuel cells/cells (PETE)

Solid acid fuel cells/cells (SCFC)

Various fuel cell modules. fuel cell battery

Comparative analysis of types and varieties of fuel cells

Fuel cell/cell applications

Application of fuel cells/cells in telecommunication systems

Application of fuel cells/cells in communication networks

Application of fuel cells/cells in data networks

Application of fuel cells/cells in security systems

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

Application of fuel cells/cells in distribution networks

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

Chemistry as a source of electricity

Rechargeable

Solid electrolyte

Hydrogen fuel cells

Fuel Cell Efficiency

Alternative electrochemical storage

* * *

The principle of operation of fuel cells

Invention of fuel cells

Polymer exchange membrane fuel cell (PEMFC)

Solid oxide fuel cell (SOFC)

Alkaline fuel cell (AFC)

Molten-carbonate fuel cell (MCFC)

Phosphoric-acid fuel cell (PAFC)

Fuel cell with polymer exchange membrane

Fuel Cell Efficiency

Efficiency of a gasoline engine and a car on electric batteries

Why use fuel cells?

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THE BELL