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  • A fuel cell is a device that converts the chemical energy from a fuel into electricity

  • through a chemical reaction with oxygen or another oxidizing agent.

  • Hydrogen produced from the steam methane reforming of natural gas is the most common fuel, but

  • for greater efficiency hydrocarbons can be used directly such as natural gas and alcohols

  • like methanol. Fuel cells are different from batteries in that they require a continuous

  • source of fuel and oxygen/air to sustain the chemical reaction whereas in a battery the

  • chemicals present in the battery react with each other to generate an electromotive force.

  • Fuel cells can produce electricity continuously for as long as these inputs are supplied.

  • The first fuel cells were invented in 1838. The first commercial use of fuel cells came

  • more than a century later in NASA space programs to generate power for probes, satellites and

  • space capsules. Since then, fuel cells have been used in many other applications. Fuel

  • cells are used for primary and backup power for commercial, industrial and residential

  • buildings and in remote or inaccessible areas. They are also used to power fuel-cell vehicles,

  • including forklifts, automobiles, buses, boats, motorcycles and submarines.

  • There are many types of fuel cells, but they all consist of an anode, a cathode and an

  • electrolyte that allows charges to move between the two sides of the fuel cell. Electrons

  • are drawn from the anode to the cathode through an external circuit, producing direct current

  • electricity. As the main difference among fuel cell types is the electrolyte, fuel cells

  • are classified by the type of electrolyte they use followed by the difference in startup

  • time ranging from 1 sec for PEMFC to 10 min for SOFC. Fuel cells come in a variety of

  • sizes. Individual fuel cells produce relatively small electrical potentials, about 0.7 volts,

  • so cells are "stacked", or placed in series, to increase the voltage and meet an application's

  • requirements. In addition to electricity, fuel cells produce water, heat and, depending

  • on the fuel source, very small amounts of nitrogen dioxide and other emissions. The

  • energy efficiency of a fuel cell is generally between 40–60%, or up to 85% efficient in

  • cogeneration if waste heat is captured for use.

  • The fuel cell market is growing, and Pike Research has estimated that the stationary

  • fuel cell market will reach 50 GW by 2020.

  • History

  • The first references to hydrogen fuel cells appeared in 1838. In a letter dated October

  • 1838 but published in the December 1838 edition of The London and Edinburgh Philosophical

  • Magazine and Journal of Science, Welsh physicist and barrister William Grove wrote about the

  • development of his first crude fuel cells. He used a combination of sheet iron, copper

  • and porcelain plates, and a solution of sulphate of copper and dilute acid. In a letter to

  • the same publication written in December 1838 but published in June 1839, German physicist

  • Christian Friedrich Schönbein discussed the first crude fuel cell that he had invented.

  • His letter discussed current generated from hydrogen and oxygen dissolved in water. Grove

  • later sketched his design, in 1842, in the same journal. The fuel cell he made used similar

  • materials to today's phosphoric-acid fuel cell.

  • In 1939, British engineer Francis Thomas Bacon successfully developed a 5 kW stationary

  • fuel cell. In 1955, W. Thomas Grubb, a chemist working for the General Electric Company,

  • further modified the original fuel cell design by using a sulphonated polystyrene ion-exchange

  • membrane as the electrolyte. Three years later another GE chemist, Leonard Niedrach, devised

  • a way of depositing platinum onto the membrane, which served as catalyst for the necessary

  • hydrogen oxidation and oxygen reduction reactions. This became known as the "Grubb-Niedrach fuel

  • cell". GE went on to develop this technology with NASA and McDonnell Aircraft, leading

  • to its use during Project Gemini. This was the first commercial use of a fuel cell. In

  • 1959, a team led by Harry Ihrig built a 15 kW fuel cell tractor for Allis-Chalmers, which

  • was demonstrated across the U.S. at state fairs. This system used potassium hydroxide

  • as the electrolyte and compressed hydrogen and oxygen as the reactants. Later in 1959,

  • Bacon and his colleagues demonstrated a practical five-kilowatt unit capable of powering a welding

  • machine. In the 1960s, Pratt and Whitney licensed Bacon's U.S. patents for use in the U.S. space

  • program to supply electricity and drinking water. In 1991, the first hydrogen fuel cell

  • automobile was developed by Roger Billings. UTC Power was the first company to manufacture

  • and commercialize a large, stationary fuel cell system for use as a co-generation power

  • plant in hospitals, universities and large office buildings. UTC Power continues to be

  • the sole supplier of fuel cells to NASA for use in space vehicles, having supplied fuel

  • cells for the Apollo missions, and the Space Shuttle program, and is developing fuel cells

  • for cell phone towers and other applications. Types of fuel cells; design

  • Fuel cells come in many varieties; however, they all work in the same general manner.

  • They are made up of three adjacent segments: the anode, the electrolyte, and the cathode.

  • Two chemical reactions occur at the interfaces of the three different segments. The net result

  • of the two reactions is that fuel is consumed, water or carbon dioxide is created, and an

  • electric current is created, which can be used to power electrical devices, normally

  • referred to as the load. At the anode a catalyst oxidizes the fuel,

  • usually hydrogen, turning the fuel into a positively charged ion and a negatively charged

  • electron. The electrolyte is a substance specifically designed so ions can pass through it, but

  • the electrons cannot. The freed electrons travel through a wire creating the electric

  • current. The ions travel through the electrolyte to the cathode. Once reaching the cathode,

  • the ions are reunited with the electrons and the two react with a third chemical, usually

  • oxygen, to create water or carbon dioxide.

  • The most important design features in a fuel cell are:

  • The electrolyte substance. The electrolyte substance usually defines the type of fuel

  • cell. The fuel that is used. The most common fuel

  • is hydrogen. The anode catalyst breaks down the fuel into

  • electrons and ions. The anode catalyst is usually made up of very fine platinum powder.

  • The cathode catalyst turns the ions into the waste chemicals like water or carbon dioxide.

  • The cathode catalyst is often made up of nickel but it can also be a nanomaterial-based catalyst.

  • A typical fuel cell produces a voltage from 0.6 V to 0.7 V at full rated load. Voltage

  • decreases as current increases, due to several factors:

  • Activation loss Ohmic loss

  • Mass transport loss. To deliver the desired amount of energy, the

  • fuel cells can be combined in series to yield higher voltage, and in parallel to allow a

  • higher current to be supplied. Such a design is called a fuel cell stack. The cell surface

  • area can also be increased, to allow higher current from each cell. Within the stack,

  • reactant gases must be distributed uniformly over each of the cells to maximize the power

  • output. Proton exchange membrane fuel cells

  • In the archetypical hydrogenoxide proton exchange membrane fuel cell design, a proton-conducting

  • polymer membrane separates the anode and cathode sides. This was called a "solid polymer electrolyte

  • fuel cell" in the early 1970s, before the proton exchange mechanism was well-understood.

  • On the anode side, hydrogen diffuses to the anode catalyst where it later dissociates

  • into protons and electrons. These protons often react with oxidants causing them to

  • become what are commonly referred to as multi-facilitated proton membranes. The protons are conducted

  • through the membrane to the cathode, but the electrons are forced to travel in an external

  • circuit because the membrane is electrically insulating. On the cathode catalyst, oxygen

  • molecules react with the electrons and protons to form water.

  • In addition to this pure hydrogen type, there are hydrocarbon fuels for fuel cells, including

  • diesel, methanol and chemical hydrides. The waste products with these types of fuel are

  • carbon dioxide and water, when hydrogen is used the CO2 is released when methane from

  • natural gas is combined with steam in a process called steam methane reforming to produce

  • the hydrogen, this can take place in a different location to the fuel cell potentially allowing

  • the hydrogen fuel cell to be used indoors for example in fork lifts.

  • The different components of a PEMFC are; bipolar plates,

  • electrodes, catalyst,

  • membrane, and the necessary hardware.

  • The materials used for different parts of the fuel cells differ by type. The bipolar

  • plates may be made of different types of materials, such as, metal, coated metal, graphite, flexible

  • graphite, C–C composite, carbonpolymer composites etc. The membrane electrode assembly

  • is referred as the heart of the PEMFC and is usually made of a proton exchange membrane

  • sandwiched between two catalyst-coated carbon papers. Platinum and/or similar type of noble

  • metals are usually used as the catalyst for PEMFC. The electrolyte could be a polymer

  • membrane. Proton exchange membrane fuel cell design

  • issues Costs. In 2013, the Department of Energy estimated

  • that 80-kW automotive fuel cell system costs of US$67 per kilowatt could be achieved, assuming

  • volume production of 100,000 automotive units per year and US$55 per kilowatt could be achieved,

  • assuming volume production of 500,000 units per year. In 2008, professor Jeremy P. Meyers

  • estimated that cost reductions over a production ramp-up period will take about 20 years after

  • fuel-cell cars are introduced before they will be able to compete commercially with

  • current market technologies, including gasoline internal combustion engines. Many companies

  • are working on techniques to reduce cost in a variety of ways including reducing the amount

  • of platinum needed in each individual cell. Ballard Power Systems has experimented with

  • a catalyst enhanced with carbon silk, which allows a 30% reduction in platinum usage without

  • reduction in performance. Monash University, Melbourne uses PEDOT as a cathode. A 2011

  • published study documented the first metal-free electrocatalyst using relatively inexpensive

  • doped carbon nanotubes, which are less than 1% the cost of platinum and are of equal or

  • superior performance. Water and air management. In this type of

  • fuel cell, the membrane must be hydrated, requiring water to be evaporated at precisely

  • the same rate that it is produced. If water is evaporated too quickly, the membrane dries,

  • resistance across it increases, and eventually it will crack, creating a gas "short circuit"

  • where hydrogen and oxygen combine directly, generating heat that will damage the fuel

  • cell. If the water is evaporated too slowly, the electrodes will flood, preventing the

  • reactants from reaching the catalyst and stopping the reaction. Methods to manage water in cells

  • are being developed like electroosmotic pumps focusing on flow control. Just as in a combustion

  • engine, a steady ratio between the reactant and oxygen is necessary to keep the fuel cell

  • operating efficiently. Temperature management. The same temperature

  • must be maintained throughout the cell in order to prevent destruction of the cell through

  • thermal loading. This is particularly challenging as the 2H2 + O2 -> 2H2O reaction is highly

  • exothermic, so a large quantity of heat is generated within the fuel cell.

  • Durability, service life, and special requirements for some type of cells. Stationary fuel cell

  • applications typically require more than 40,000 hours of reliable operation at a temperature

  • of −35 °C to 40 °C, while automotive fuel cells require a 5,000-hour lifespan)

  • under extreme temperatures. Current service life is 7,300 hours under cycling conditions.

  • Automotive engines must also be able to start reliably at −30 °C and have a high power-to-volume

  • ratio. Limited carbon monoxide tolerance of some

  • cathodes. Phosphoric acid fuel cell

  • Phosphoric acid fuel cells were first designed and introduced in 1961 by G. V. Elmore and

  • H. A. Tanner. In these cells phosphoric acid is used as a non-conductive electrolyte to

  • pass positive hydrogen ions from the anode to the cathode. These cells commonly work

  • in temperatures of 150 to 200 degrees Celsius. This high temperature will cause heat and

  • energy loss if the heat is not removed and used properly. This heat can be used to produce

  • steam for air conditioning systems or any other thermal energy consuming system. Using

  • this heat in cogeneration can enhance the efficiency of phosphoric acid fuel cells from

  • 40–50% to about 80%. Phosphoric acid, the electrolyte used in PAFCs, is a non-conductive

  • liquid acid which forces electrons to travel from anode to cathode through an external

  • electrical circuit. Since the hydrogen ion production rate on the anode is small, platinum

  • is used as catalyst to increase this ionization rate. A key disadvantage of these cells is

  • the use of an acidic electrolyte. This increases the corrosion or oxidation of components exposed

  • to phosphoric acid. High-temperature fuel cells

  • SOFC

  • Solid oxide fuel cells use a solid material, most commonly a ceramic material called yttria-stabilized

  • zirconia, as the electrolyte. Because SOFCs are made entirely of solid materials, they

  • are not limited to the flat plane configuration of other types of fuel cells and are often

  • designed as rolled tubes. They require high operating temperatures and can be run on a

  • variety of fuels including natural gas. SOFCs are unique in that negatively charged

  • oxygen ions travel from the cathode to the anode instead of positively charged hydrogen

  • ions travelling from the anode to the cathode, as is the case in all other types of fuel

  • cells. Oxygen gas is fed through the cathode, where it absorbs electrons to create oxygen

  • ions. The oxygen ions then travel through the electrolyte to react with hydrogen gas

  • at the anode. The reaction at the anode produces electricity and water as by-products. Carbon

  • dioxide may also be a by-product depending on the fuel, but the carbon emissions from

  • an SOFC system are less than those from a fossil fuel combustion plant. The chemical

  • reactions for the SOFC system can be expressed as follows:

  • Anode Reaction: 2H2 + 2O2− → 2H2O + 4e− Cathode Reaction: O2 + 4e– → 2O2−

  • Overall Cell Reaction: 2H2 + O2 → 2H2O SOFC systems can run on fuels other than pure

  • hydrogen gas. However, since hydrogen is necessary for the reactions listed above, the fuel selected

  • must contain hydrogen atoms. For the fuel cell to operate, the fuel must be converted

  • into pure hydrogen gas. SOFCs are capable of internally reforming light hydrocarbons

  • such as methane, propane and butane. These fuel cells are at an early stage of development.

  • Challenges exist in SOFC systems due to their high operating temperatures. One such challenge

  • is the potential for carbon dust to build up on the anode, which slows down the internal

  • reforming process. Research to address this "carbon coking" issue at the University of

  • Pennsylvania has shown that the use of copper-based cermet can reduce coking and the loss of performance.

  • Another disadvantage of SOFC systems is slow start-up time, making SOFCs less useful for

  • mobile applications. Despite these disadvantages, a high operating temperature provides an advantage

  • by removing the need for a precious metal catalyst like platinum, thereby reducing cost.

  • Additionally, waste heat from SOFC systems may be captured and reused, increasing the

  • theoretical overall efficiency to as high as 80%–85%.

  • The high operating temperature is largely due to the physical properties of the YSZ

  • electrolyte. As temperature decreases, so does the ionic conductivity of YSZ. Therefore,

  • to obtain optimum performance of the fuel cell, a high operating temperature is required.

  • According to their website, Ceres Power, a UK SOFC fuel cell manufacturer, has developed

  • a method of reducing the operating temperature of their SOFC system to 500–600 degrees

  • Celsius. They replaced the commonly used YSZ electrolyte with a CGO electrolyte. The lower

  • operating temperature allows them to use stainless steel instead of ceramic as the cell substrate,

  • which reduces cost and start-up time of the system.

  • MCFC

  • Molten carbonate fuel cells require a high operating temperature, 650 °C, similar to

  • SOFCs. MCFCs use lithium potassium carbonate salt as an electrolyte, and this salt liquefies

  • at high temperatures, allowing for the movement of charge within the cellin this case,

  • negative carbonate ions. Like SOFCs, MCFCs are capable of converting

  • fossil fuel to a hydrogen-rich gas in the anode, eliminating the need to produce hydrogen

  • externally. The reforming process creates CO

  • 2 emissions. MCFC-compatible fuels include natural gas, biogas and gas produced from

  • coal. The hydrogen in the gas reacts with carbonate ions from the electrolyte to produce

  • water, carbon dioxide, electrons and small amounts of other chemicals. The electrons

  • travel through an external circuit creating electricity and return to the cathode. There,

  • oxygen from the air and carbon dioxide recycled from the anode react with the electrons to

  • form carbonate ions that replenish the electrolyte, completing the circuit. The chemical reactions

  • for an MCFC system can be expressed as follows: Anode Reaction: CO32− + H2 → H2O + CO2

  • + 2e− Cathode Reaction: CO2 + ½O2 + 2e− → CO32−

  • Overall Cell Reaction: H2 + ½O2 → H2O As with SOFCs, MCFC disadvantages include

  • slow start-up times because of their high operating temperature. This makes MCFC systems

  • not suitable for mobile applications, and this technology will most likely be used for

  • stationary fuel cell purposes. The main challenge of MCFC technology is the cells' short life

  • span. The high-temperature and carbonate electrolyte lead to corrosion of the anode and cathode.

  • These factors accelerate the degradation of MCFC components, decreasing the durability

  • and cell life. Researchers are addressing this problem by exploring corrosion-resistant

  • materials for components as well as fuel cell designs that may increase cell life without

  • decreasing performance. MCFCs hold several advantages over other fuel

  • cell technologies, including their resistance to impurities. They are not prone to "carbon

  • coking", which refers to carbon build-up on the anode that results in reduced performance

  • by slowing down the internal fuel reforming process. Therefore, carbon-rich fuels like

  • gases made from coal are compatible with the system. The Department of Energy claims that

  • coal, itself, might even be a fuel option in the future, assuming the system can be

  • made resistant to impurities such as sulfur and particulates that result from converting

  • coal into hydrogen. MCFCs also have relatively high efficiencies. They can reach a fuel-to-electricity

  • efficiency of 50%, considerably higher than the 37–42% efficiency of a phosphoric acid

  • fuel cell plant. Efficiencies can be as high as 65% when the fuel cell is paired with a

  • turbine, and 85% if heat is captured and used in a Combined Heat and Power system.

  • FuelCell Energy, a Connecticut-based fuel cell manufacturer, develops and sells MCFC

  • fuel cells. The company says that their MCFC products range from 300 kW to 2.8 MW systems

  • that achieve 47% electrical efficiency and can utilize CHP technology to obtain higher

  • overall efficiencies. One product, the DFC-ERG, is combined with a gas turbine and, according

  • to the company, it achieves an electrical efficiency of 65%.

  • Comparison of fuel cell types Efficiency of leading fuel cell types

  • Glossary of Terms in table: Anode: The electrode at which oxidation takes

  • place. For fuel cells and other galvanic cells, the anode is the negative terminal; for electrolytic

  • cells, the anode is the positive terminal. Aqueous solution: a: of, relating to, or resembling

  • water b : made from, with, or by water. Catalyst: A chemical substance that increases

  • the rate of a reaction without being consumed; after the reaction, it can potentially be

  • recovered from the reaction mixture and is chemically unchanged. The catalyst lowers

  • the activation energy required, allowing the reaction to proceed more quickly or at a lower

  • temperature. In a fuel cell, the catalyst facilitates the reaction of oxygen and hydrogen.

  • It is usually made of platinum powder very thinly coated onto carbon paper or cloth.

  • The catalyst is rough and porous so the maximum surface area of the platinum can be exposed

  • to the hydrogen or oxygen. The platinum-coated side of the catalyst faces the membrane in

  • the fuel cell. Cathode: The electrode at which reduction

  • occurs. For fuel cells and other galvanic cells, the cathode is the positive terminal;

  • for electrolytic cells, the cathode is the negative terminal.

  • Electrolyte: A substance that conducts charged ions from one electrode to the other in a

  • fuel cell, battery, or electrolyzer. Fuel Cell Stack: Individual fuel cells connected

  • in a series. Fuel cells are stacked to increase voltage.

  • Matrix: something within or from which something else originates, develops, or takes form.

  • Membrane: The separating layer in a fuel cell that acts as electrolyte as well as a barrier

  • film separating the gases in the anode and cathode compartments of the fuel cell.

  • Molten Carbonate Fuel Cell: A type of fuel cell that contains a molten carbonate electrolyte.

  • Carbonate ions are transported from the cathode to the anode. Operating temperatures are typically

  • near 650 °C. Phosphoric acid fuel cell: A type of fuel

  • cell in which the electrolyte consists of concentrated phosphoric acid. Protons are

  • transported from the anode to the cathode. The operating temperature range is generally

  • 160–220 °C. Polymer Electrolyte Membrane: A fuel cell

  • incorporating a solid polymer membrane used as its electrolyte. Protons are transported

  • from the anode to the cathode. The operating temperature range is generally 60–100 °C.

  • Solid Oxide Fuel Cell: A type of fuel cell in which the electrolyte is a solid, nonporous

  • metal oxide, typically zirconium oxide treated with Y2O3, and O2− is transported from the

  • cathode to the anode. Any CO in the reformate gas is oxidized to CO2 at the anode. Temperatures

  • of operation are typically 800–1,000 °C. Solution: a: an act or the process by which

  • a solid, liquid, or gaseous substance is homogeneously mixed with a liquid or sometimes a gas or

  • solid, b : a homogeneous mixture formed by this process; especially : a single-phase

  • liquid system, c : the condition of being dissolved

  • For more information see Glossary of fuel cell terms

  • Theoretical maximum efficiency The energy efficiency of a system or device

  • that converts energy is measured by the ratio of the amount of useful energy put out by

  • the system to the total amount of energy that is put in or by useful output energy as a

  • percentage of the total input energy. In the case of fuel cells, useful output energy is

  • measured in electrical energy produced by the system. Input energy is the energy stored

  • in the fuel. According to the U.S. Department of Energy, fuel cells are generally between

  • 40–60% energy efficient. This is higher than some other systems for energy generation.

  • For example, the typical internal combustion engine of a car is about 25% energy efficient.

  • In combined heat and power systems, the heat produced by the fuel cell is captured and

  • put to use, increasing the efficiency of the system to up to 85–90%.

  • The theoretical maximum efficiency of any type of power generation system is never reached

  • in practice, and it does not consider other steps in power generation, such as production,

  • transportation and storage of fuel and conversion of the electricity into mechanical power.

  • However, this calculation allows the comparison of different types of power generation. The

  • maximum theoretical energy efficiency of a fuel cell is 83%, operating at low power density

  • and using pure hydrogen and oxygen as reactants According to the World Energy Council, this

  • compares with a maximum theoretical efficiency of 58% for internal combustion engines. While

  • these efficiencies are not approached in most real world applications, high-temperature

  • fuel cells can theoretically be combined with gas turbines to allow stationary fuel cells

  • to come closer to the theoretical limit. A gas turbine would capture heat from the fuel

  • cell and turn it into mechanical energy to increase the fuel cell's operational efficiency.

  • This solution has been predicted to increase total efficiency to as much as 70%.

  • In practice The tank-to-wheel efficiency of a fuel-cell

  • vehicle is greater than 45% at low loads and shows average values of about 36% when a driving

  • cycle like the NEDC is used as test procedure. The comparable NEDC value for a Diesel vehicle

  • is 22%. In 2008 Honda released a demonstration fuel cell electric vehicle with fuel stack

  • claiming a 60% tank-to-wheel efficiency. It is also important to take losses due to

  • fuel production, transportation, and storage into account. Fuel cell vehicles running on

  • compressed hydrogen may have a power-plant-to-wheel efficiency of 22% if the hydrogen is stored

  • as high-pressure gas, and 17% if it is stored as liquid hydrogen. Fuel cells cannot store

  • energy like a battery, except as hydrogen, but in some applications, such as stand-alone

  • power plants based on discontinuous sources such as solar or wind power, they are combined

  • with electrolyzers and storage systems to form an energy storage system. Most hydrogen,

  • however, is produced by steam methane reforming, and so most hydrogen production emits carbon

  • dioxide. The overall efficiency of such plants, using pure hydrogen and pure oxygen can be

  • "from 35 up to 50 percent", depending on gas density and other conditions. While a much

  • cheaper leadacid battery might return about 90%, the electrolyzer/fuel cell system can

  • store indefinite quantities of hydrogen, and is therefore better suited for long-term storage.

  • Solid-oxide fuel cells produce exothermic heat from the recombination of the oxygen

  • and hydrogen. The ceramic can run as hot as 800 degrees Celsius. This heat can be captured

  • and used to heat water in a micro combined heat and power application. When the heat

  • is captured, total efficiency can reach 80–90% at the unit, but does not consider production

  • and distribution losses. CHP units are being developed today for the European home market.

  • Professor Jeremy P. Meyers, in the Electrochemical Society journal Interface in 2008, wrote,

  • "While fuel cells are efficient relative to combustion engines, they are not as efficient

  • as batteries, due primarily to the inefficiency of the oxygen reduction reaction.... [T]hey

  • make the most sense for operation disconnected from the grid, or when fuel can be provided

  • continuously. For applications that require frequent and relatively rapid start-ups ... where

  • zero emissions are a requirement, as in enclosed spaces such as warehouses, and where hydrogen

  • is considered an acceptable reactant, a [PEM fuel cell] is becoming an increasingly attractive

  • choice [if exchanging batteries is inconvenient]". In 2013 military organisations are evaluating

  • fuel cells to significantly reduce the battery weight carried by soldiers.

  • Applications

  • Power Stationary fuel cells are used for commercial,

  • industrial and residential primary and backup power generation. Fuel cells are very useful

  • as power sources in remote locations, such as spacecraft, remote weather stations, large

  • parks, communications centers, rural locations including research stations, and in certain

  • military applications. A fuel cell system running on hydrogen can be compact and lightweight,

  • and have no major moving parts. Because fuel cells have no moving parts and do not involve

  • combustion, in ideal conditions they can achieve up to 99.9999% reliability. This equates to

  • less than one minute of downtime in a six-year period.

  • Since fuel cell electrolyzer systems do not store fuel in themselves, but rather rely

  • on external storage units, they can be successfully applied in large-scale energy storage, rural

  • areas being one example. There are many different types of stationary fuel cells so efficiencies

  • vary, but most are between 40% and 60% energy efficient. However, when the fuel cell's waste

  • heat is used to heat a building in a cogeneration system this efficiency can increase to 85%.

  • This is significantly more efficient than traditional coal power plants, which are only

  • about one third energy efficient. Assuming production at scale, fuel cells could save

  • 20–40% on energy costs when used in cogeneration systems. Fuel cells are also much cleaner

  • than traditional power generation; a fuel cell power plant using natural gas as a hydrogen

  • source would create less than one ounce of pollution (other than CO

  • 2) for every 1,000 kW·h produced, compared to 25 pounds of pollutants generated by conventional

  • combustion systems. Fuel Cells also produce 97% less nitrogen oxide emissions than conventional

  • coal-fired power plants. One such pilot program is operating on Stuart

  • Island in Washington State. There the Stuart Island Energy Initiative has built a complete,

  • closed-loop system: Solar panels power an electrolyzer, which makes hydrogen. The hydrogen

  • is stored in a 500-U.S.-gallon tank at 200 pounds per square inch, and runs a ReliOn

  • fuel cell to provide full electric back-up to the off-the-grid residence. Another closed

  • system loop was unveiled in late 2011 in Hempstead, NY.

  • Fuel cells can be used with low-quality gas from landfills or waste-water treatment plants

  • to generate power and lower methane emissions. A 2.8 MW fuel cell plant in California is

  • said to be the largest of the type. Cogeneration

  • Combined heat and power fuel cell systems, including Micro combined heat and power systems

  • are used to generate both electricity and heat for homes, office building and factories.

  • The system generates constant electric power, and at the same time produces hot air and

  • water from the waste heat. As the result CHP systems have the potential to save primary

  • energy as they can make use of waste heat which is generally rejected by thermal energy

  • conversion systems. A typical capacity range of home fuel cell is 1–3 kWel / 4–8 kWth.

  • CHP systems linked to absorption chillers use their waste heat for refrigeration.

  • The waste heat from fuel cells can be diverted during the summer directly into the ground

  • providing further cooling while the waste heat during winter can be pumped directly

  • into the building. The University of Minnesota owns the patent rights to this type of system

  • Co-generation systems can reach 85% efficiency. Phosphoric-acid fuel cells comprise the largest

  • segment of existing CHP products worldwide and can provide combined efficiencies close

  • to 90%. Molten Carbonate and Solid Oxide Fuel Cells are also used for combined heat and

  • power generation and have electrical energy efficiences around 60%. Disadvantages of co-generation

  • systems include slow ramping up and down rates, high cost and short lifetime. Also their need

  • to have a hot water storage tank to smooth out the thermal heat production was a serious

  • disadvantage in the domestic market place where space in domestic properties is at a

  • great premium. Fuel cell electric vehicles

  • Automobiles Although there are currently no fuel cell

  • vehicles available for commercial sale, over 20 fuel cell electric vehicle prototypes and

  • demonstration cars have been released since 2009. Demonstration models include the Honda

  • FCX Clarity, Toyota FCHV-adv, and Mercedes-Benz F-Cell. As of June 2011 demonstration FCEVs

  • had driven more than 4,800,000 km, with more than 27,000 refuelings. Demonstration fuel

  • cell vehicles have been produced with "a driving range of more than 400 km between refueling".

  • They can be refueled in less than 5 minutes. The U.S. Department of Energy's Fuel Cell

  • Technology Program claims that, as of 2011, fuel cells achieved 53–59% efficiency at

  • one-quarter power and 42–53% vehicle efficiency at full power, and a durability of over 120,000 km

  • with less than 10% degradation. In a Well-to-Wheels simulation analysis, that "did not address

  • the economics and market constraints", General Motors and its partners estimated that per

  • mile traveled, a fuel cell electric vehicle running on compressed gaseous hydrogen produced

  • from natural gas could use about 40% less energy and emit 45% less greenhouse gasses

  • than an internal combustion vehicle. A lead engineer from the Department of Energy whose

  • team is testing fuel cell cars said in 2011 that the potential appeal is that "these are

  • full-function vehicles with no limitations on range or refueling rate so they are a direct

  • replacement for any vehicle. For instance, if you drive a full sized SUV and pull a boat

  • up into the mountains, you can do that with this technology and you can't with current

  • battery-only vehicles, which are more geared toward city driving."

  • Some experts believe, however, that fuel cell cars will never become economically competitive

  • with other technologies or that it will take decades for them to become profitable. In

  • July 2011, the chairman and CEO of General Motors, Daniel Akerson, stated that while

  • the cost of hydrogen fuel cell cars is decreasing: "The car is still too expensive and probably

  • won't be practical until the 2020-plus period, I don't know."

  • In 2012, Lux Research, Inc. issued a report that stated: "The dream of a hydrogen economy

  • ... is no nearer". It concluded that "Capital cost ... will limit adoption to a mere 5.9

  • GW" by 2030, providing "a nearly insurmountable barrier to adoption, except in niche applications".

  • The analysis concluded that, by 2030, PEM stationary market will reach $1 billion, while

  • the vehicle market, including forklifts, will reach a total of $2 billion. Other analyses

  • cite the lack of an extensive hydrogen infrastructure in the U.S. as an ongoing challenge to Fuel

  • Cell Electric Vehicle commercialization. In 2006, a study for the IEEE showed that for

  • hydrogen produced via electrolysis of water: "Only about 25% of the power generated from

  • wind, water, or sun is converted to practical use." The study further noted that "Electricity

  • obtained from hydrogen fuel cells appears to be four times as expensive as electricity

  • drawn from the electrical transmission grid. ... Because of the high energy losses [hydrogen]

  • cannot compete with electricity." Furthermore, the study found: "Natural gas reforming is

  • not a sustainable solution". "The large amount of energy required to isolate hydrogen from

  • natural compounds, package the light gas by compression or liquefaction, transfer the

  • energy carrier to the user, plus the energy lost when it is converted to useful electricity

  • with fuel cells, leaves around 25% for practical use."

  • Despite this, several major car manufacturers have announced plans to introduce a production

  • model of a fuel cell car in 2015. In 2013, Toyota has stated that it plans to introduce

  • such a vehicle at a price of less than US$100,000. Mercedes-Benz announced that they would move

  • the scheduled production date of their fuel cell car from 2015 up to 2014, asserting that

  • "The product is ready for the market technically. ... The issue is infrastructure." At the Paris

  • Auto Show in September 2012, Hyundai announced that it plans to begin producing a commercial

  • production fuel cell model in December 2012 and hopes to deliver 1,000 of them by 2015.

  • Other manufacturers planning to sell fuel cell electric vehicles commercially by 2016

  • or earlier include General Motors, Honda, and Nissan.

  • The Obama Administration sought to reduce funding for the development of fuel cell vehicles,

  • concluding that other vehicle technologies will lead to quicker reduction in emissions

  • in a shorter time. Steven Chu, the United States Secretary of Energy, stated in 2009

  • that hydrogen vehicles "will not be practical over the next 10 to 20 years". In 2012, however,

  • Chu stated that he saw fuel cell cars as more economically feasible as natural gas prices

  • have fallen and hydrogen reforming technologies have improved.

  • Buses

  • As of August 2011, there were a total of approximately 100 fuel cell buses deployed around the world.

  • Most buses are produced by UTC Power, Toyota, Ballard, Hydrogenics, and Proton Motor. UTC

  • Buses had accumulated over 970,000 km of driving by 2011. Fuel cell buses have a 39–141%

  • higher fuel economy than diesel buses and natural gas buses. Fuel cell buses have been

  • deployed around the world including in Whistler, Canada; San Francisco, United States; Hamburg,

  • Germany; Shanghai, China; London, England; São Paulo, Brazil; as well as several others.

  • The Fuel Cell Bus Club is a global cooperative effort in trial fuel cell buses. Notable Projects

  • Include: 12 Fuel cell buses are being deployed in the

  • Oakland and San Francisco Bay area of California. Daimler AG, with thirty-six experimental buses

  • powered by Ballard Power Systems fuel cells completed a successful three-year trial, in

  • eleven cities, in January 2007. A fleet of Thor buses with UTC Power fuel

  • cells was deployed in California, operated by SunLine Transit Agency.

  • The first Brazilian hydrogen fuel cell bus prototype in Brazil was deployed in São Paulo.

  • The bus was manufactured in Caxias do Sul and the hydrogen fuel will be produced in

  • São Bernardo do Campo from water through electrolysis. The program, callednibus

  • Brasileiro a Hidrogênio", includes three additional buses.

  • Forklifts A fuel cell forklift is a fuel cell powered

  • industrial forklift truck used to lift and transport materials. Most fuel cells used

  • for material handling purposes are powered by PEM fuel cells.

  • In 2013 there were over 4,000 fuel cell forklifts used in material handling in the USA, of which

  • only 500 received funding from DOE. Fuel cell fleets are operated by a large number of companies,

  • including Sysco Foods, FedEx Freight, GENCO, and H-E-B Grocers. Europe demonstrated 30

  • Fuel cell forklifts with Hylift and extended it with HyLIFT-EUROPE to 200 units, with other

  • projects in France and Austria. Pike Research stated in 2011 that fuel-cell-powered forklifts

  • will be the largest driver of hydrogen fuel demand by 2020.

  • PEM fuel-cell-powered forklifts provide significant benefits over both petroleum and battery powered

  • forklifts as they produce no local emissions, can work for a full 8-hour shift on a single

  • tank of hydrogen, can be refueled in 3 minutes and have a lifetime of 8–10 years. Fuel

  • cell-powered forklifts are often used in refrigerated warehouses, as their performance is not degraded

  • by lower temperatures. Many companies do not use petroleum powered forklifts, as these

  • vehicles work indoors where emissions must be controlled and instead are turning to electric

  • forklifts. In design the FC units are often made as drop-in replacements.

  • Motorcycles and bicycles In 2005 a British manufacturer of hydrogen-powered

  • fuel cells, Intelligent Energy, produced the first working hydrogen run motorcycle called

  • the ENV. The motorcycle holds enough fuel to run for four hours, and to travel 160 km

  • in an urban area, at a top speed of 80 km/h. In 2004 Honda developed a fuel-cell motorcycle

  • that utilized the Honda FC Stack. Other examples of motorbikes and bicycles

  • that use hydrogen fuel cells include the Taiwanese company APFCT's scooter using the fueling

  • system from Italy's Acta SpA and the Suzuki Burgman scooter with an IE fuel cell that

  • received EU Whole Vehicle Type Approval in 2011. Suzuki Motor Corp. and IE have announced

  • a joint venture to accelerate the commercialization of zero-emission vehicles.

  • Airplanes Boeing researchers and industry partners throughout

  • Europe conducted experimental flight tests in February 2008 of a manned airplane powered

  • only by a fuel cell and lightweight batteries. The fuel cell demonstrator airplane, as it

  • was called, used a proton exchange membrane fuel cell/lithium-ion battery hybrid system

  • to power an electric motor, which was coupled to a conventional propeller. In 2003, the

  • world's first propeller-driven airplane to be powered entirely by a fuel cell was flown.

  • The fuel cell was a unique FlatStackTM stack design, which allowed the fuel cell to be

  • integrated with the aerodynamic surfaces of the plane.

  • There have been several fuel-cell-powered unmanned aerial vehicles. A Horizon fuel cell

  • UAV set the record distance flown for a small UAV in 2007. The military is especially interested

  • in this application because of the low noise, low thermal signature and ability to attain

  • high altitude. In 2009 the Naval Research Laboratory's Ion Tiger utilized a hydrogen-powered

  • fuel cell and flew for 23 hours and 17 minutes. Fuel cells are also being used to provide

  • auxiliary power in aircraft, replacing fossil fuel generators that were previously used

  • to start the engines and power on board electrical needs. Fuel cells can help airplanes reduce

  • CO 2 and other pollutant emissions and noise.

  • Boats

  • The world's first fuel-cell boat HYDRA used an AFC system with 6.5 kW net output. Iceland

  • has committed to converting its vast fishing fleet to use fuel cells to provide auxiliary

  • power by 2015 and, eventually, to provide primary power in its boats. Amsterdam recently

  • introduced its first fuel-cell-powered boat that ferries people around the city's famous

  • and beautiful canals. Submarines

  • The Type 212 submarines of the German and Italian navies use fuel cells to remain submerged

  • for weeks without the need to surface. The U212A is a non-nuclear submarine developed

  • by German naval shipyard Howaldtswerke Deutsche Werft. The system consists of nine PEM fuel

  • cells, providing between 30 kW and 50 kW each. The ship is silent giving it an advantage

  • in the detection of other submarines. Portable power systems

  • Portable power systems that use fuel cells can be used in the leisure sector, the industrial

  • sector, and in the military sector. SFC Energy is a German manufacturer of direct methanol

  • fuel cells for a variety of portable power systems. Ensol Systems Inc. is an integrator

  • of portable power systems, using the SFC Energy DMFC.

  • Other applications Providing power for base stations or cell

  • sites Distributed generation

  • Emergency power systems are a type of fuel cell system, which may include lighting, generators

  • and other apparatus, to provide backup resources in a crisis or when regular systems fail.

  • They find uses in a wide variety of settings from residential homes to hospitals, scientific

  • laboratories, data centers, telecommunication equipment and modern naval

  • ships. An uninterrupted power supply provides emergency

  • power and, depending on the topology, provide line regulation as well to connected equipment

  • by supplying power from a separate source when utility power is not available. Unlike

  • a standby generator, it can provide instant protection from a momentary power interruption.

  • Base load power plants Solar Hydrogen Fuel Cell Water Heating

  • Hybrid vehicles, pairing the fuel cell with either an ICE or a battery.

  • Notebook computers for applications where AC charging may not be readily available.

  • Portable charging docks for small electronics. Smartphones, laptops and tablets.

  • Small heating appliances Food preservation, achieved by exhausting

  • the oxygen and automatically maintaining oxygen exhaustion in a shipping container, containing,

  • for example, fresh fish. Breathalyzers, where the amount of voltage

  • generated by a fuel cell is used to determine the concentration of fuel in the sample.

  • Carbon monoxide detector, electrochemical sensor.

  • Fueling stations

  • There were over 85 hydrogen refueling stations in the U.S. in 2010.

  • As of June 2012 California had 23 hydrogen refueling stations in operation. Honda announced

  • plans in March 2011 to open the first station that would generate hydrogen through solar-powered

  • renewable electrolysis. South Carolina also has two hydrogen fueling stations, in Aiken

  • and Columbia, SC. The University of South Carolina, a founding member of the South Carolina

  • Hydrogen & Fuel Cell Alliance, received 12.5 million dollars from the United States Department

  • of Energy for its Future Fuels Program. The first public hydrogen refueling station

  • in Iceland was opened in Reykjavík in 2003. This station serves three buses built by DaimlerChrysler

  • that are in service in the public transport net of Reykjavík. The station produces the

  • hydrogen it needs by itself, with an electrolyzing unit, and does not need refilling: all that

  • enters is electricity and water. Royal Dutch Shell is also a partner in the project. The

  • station has no roof, in order to allow any leaked hydrogen to escape to the atmosphere.

  • The current 14 stations nationwide in Germany are planned to be expanded to 50 by 2015 through

  • its public private partnership Now GMBH. Japan also has a hydrogen highway, as part of the

  • Japan hydrogen fuel cell project. Twelve hydrogen fueling stations have been built in 11 cities

  • in Japan, and additional hydrogen stations could potentially be operational by 2015.

  • Canada, Sweden and Norway also have hydrogen highways being implemented.

  • Markets and economics

  • In 2012, fuel cell industry revenues exceeded $1 billion market value worldwide, with Asian

  • pacific countries shipping more than 3/4 of the fuel cell systems worldwide. However,

  • as of October 2013, no public company in the industry had yet become profitable. There

  • were 140,000 fuel cell stacks shipped globally in 2010, up from 11 thousand shipments in

  • 2007, and from 2011 to 2012 worldwide fuel cell shipments had an annual growth rate of

  • 85%. Tanaka Kikinzoku Kogyo K.K. expanded its production facilities for fuel cell catalysts

  • in 2013 to meet anticipated demand as the Japanese ENE Farm scheme expects to install

  • 50,000 units in 2013 and the company is experiencing rapid market growth.

  • Approximately 50% of fuel cell shipments in 2010 were stationary fuel cells, up from about

  • a third in 2009, and the four dominant producers in the Fuel Cell Industry were the United

  • States, Germany, Japan and South Korea. The Department of Energy Solid State Energy Conversion

  • Alliance found that, as of January 2011, stationary fuel cells generated power at approximately

  • $724 to $775 per kilowatt installed. In 2011, Bloom Energy, a major fuel cell supplier,

  • said that its fuel cells generated power at 9–11 cents per kilowatt-hour, including

  • the price of fuel, maintenance, and hardware. Industry groups predict that there are sufficient

  • platinum resources for future demand, and in 2007, research at Brookhaven National Laboratory

  • suggested that platinum could be replaced by a gold-palladium coating, which may be

  • less susceptible to poisoning and thereby improve fuel cell lifetime. Another method

  • would use iron and sulphur instead of platinum. This would lower the cost of a fuel cell.

  • The concept was being developed by a coalition of the John Innes Centre and the University

  • of Milan-Bicocca. PEDOT cathodes are immune to monoxide poisoning.

  • Research and development August 2005: Georgia Institute of Technology

  • researchers use triazole to raise the operating temperature of PEM fuel cells from below 100 °C

  • to over 125 °C, claiming this will require less carbon-monoxide purification of the hydrogen

  • fuel. 2008 Monash University, Melbourne uses PEDOT

  • as a cathode. 2009 Researchers at the University of Dayton,

  • in Ohio, show that arrays of vertically grown carbon nanotubes could be used as the catalyst

  • in fuel cells. 2009: Y-Carbon began to develop a carbide-derived-carbon-based

  • ultracapacitor, which they hoped would lead to fuel cells with higher energy density.

  • 2009: A nickel bisdiphosphine-based catalyst for fuel cells is demonstrated.

  • 2013: British firm ACAL Energy develops a fuel cell that it says runs for 10,000 hours

  • in simulated driving conditions. It asserts that the cost of fuel cell construction can

  • be reduced to $40/kW. See also

  • References

  • Further reading Vielstich, W., et al, ed.. Handbook of fuel

  • cells: advances in electrocatalysis, materials, diagnostics and durability. Hoboken: John

  • Wiley and SonsGregor Hoogers. Fuel Cell TechnologyHandbook.

  • CRC PressJames Larminie; Andrew Dicks. Fuel Cell Systems

  • Explained. Hoboken: John Wiley and SonsSubash C. Singhal; Kevin Kendall. High Temperature

  • Solid Oxide Fuel Cells-Fundamentals, Design and Applications. Elsevier Academic Press

  • Frano Barbir. PEM Fuel Cells-Theory and Practice. Elsevier Academic Press

  • EG&G Technical Services, Inc.. Fuel Cell Technology-Handbook, 7th Edition. U.S. Department of Energy

  • Matthew M. Mench. Fuel Cell Engines. Hoboken: John Wiley & Sons, Inc

  • Noriko Hikosaka Behling. Fuel Cells: Current Technology Challenges and Future Research

  • Needs. Elsevier Academic PressExternal links

  • Fuel Cell TodayMarket-based intelligence on the fuel cell industry

  • Fuel starvation in a hydrogen fuel cell animation Animation how a fuel cell works and applications

  • Fuel Cell Origins: 1840–1890 TC 105 IEC Technical standard for Fuel Cells

  • EERE: Hydrogen, Fuel Cells and Infrastructure Technologies Program

  • Thermodynamics of electrolysis of water and hydrogen fuel cells

  • 2002-Portable Power Applications of Fuel Cells US Fuel Cell Council

  • DoITPoMS Teaching and Learning Package- "Fuel Cells"

  • Solar Hydrogen Fuel Cell Water Heating

A fuel cell is a device that converts the chemical energy from a fuel into electricity

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    songwen8778 發佈於 2021 年 01 月 14 日
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