Fuel cell, also called fuel cell or fuel cell (commonly called fuel cell in English) consists of an electrochemical device in which a continuous flow of fuel and oxidant undergoes a controlled chemical reaction that gives rise to the products and directly supplies electrical current to an external circuit.
It is an electrochemical energy conversion device, similar to a battery. It differs in that it is designed to allow continuous supply of the consumed reagents. That is, it produces electricity from an external source of fuel and oxygen[1] or another oxidizing agent, as opposed to the limited energy storage capacity of a battery. Furthermore, in a battery the electrodes react and change depending on how charged or discharged it is; On the other hand, in a fuel cell the electrodes are catalytic and relatively stable.
The electrochemical process that takes place is highly efficient and has minimal environmental impact. Indeed, given that energy production in fuel cells is free of any intermediate thermal or mechanical process, these devices achieve higher efficiencies than thermal machines, which are limited by the efficiency of the Carnot Cycle. In general, the energy efficiency of a fuel cell is between 40-60%, and can reach > 85-90% in cogeneration, if waste heat is captured for use. On the other hand, given that the process does not involve the combustion of the reactants, polluting emissions are minimal.[2].
It is important to establish the fundamental differences between conventional batteries and fuel cells. Conventional batteries are energy storage devices: inside there are reagents that produce energy until they are consumed. However, in the fuel cell the reactants are supplied as a continuous flow from the outside, which allows energy to be generated uninterruptedly.
In principle, fuel cells could process a wide variety of reductants and oxidizers. A reductant can be any substance that can be oxidized in a chemical reaction and that can be continuously supplied (as a fluid) to the anode of a fuel cell. Likewise, the oxidant could be any fluid that can be reduced (at an appropriate rate) in the chemical reaction that takes place at the cathode.[3].
One of the first practical applications of fuel cells was in space vehicles, based on the reaction of hydrogen and oxygen, resulting in water, which can be used by astronauts for drinking, or to cool the ship's systems.[4].
fuel cell technology
Introduction
Fuel cell, also called fuel cell or fuel cell (commonly called fuel cell in English) consists of an electrochemical device in which a continuous flow of fuel and oxidant undergoes a controlled chemical reaction that gives rise to the products and directly supplies electrical current to an external circuit.
It is an electrochemical energy conversion device, similar to a battery. It differs in that it is designed to allow continuous supply of the consumed reagents. That is, it produces electricity from an external source of fuel and oxygen[1] or another oxidizing agent, as opposed to the limited energy storage capacity of a battery. Furthermore, in a battery the electrodes react and change depending on how charged or discharged it is; On the other hand, in a fuel cell the electrodes are catalytic and relatively stable.
The electrochemical process that takes place is highly efficient and has minimal environmental impact. Indeed, given that energy production in fuel cells is free of any intermediate thermal or mechanical process, these devices achieve higher efficiencies than thermal machines, which are limited by the efficiency of the Carnot Cycle. In general, the energy efficiency of a fuel cell is between 40-60%, and can reach > 85-90% in cogeneration, if waste heat is captured for use. On the other hand, given that the process does not involve the combustion of the reactants, polluting emissions are minimal.[2].
It is important to establish the fundamental differences between conventional batteries and fuel cells. Conventional batteries are energy storage devices: inside there are reagents that produce energy until they are consumed. However, in the fuel cell the reactants are supplied as a continuous flow from the outside, which allows energy to be generated uninterruptedly.
In principle, fuel cells could process a wide variety of reductants and oxidizers. A reductant can be any substance that can be oxidized in a chemical reaction and that can be continuously supplied (as a fluid) to the anode of a fuel cell. Likewise, the oxidant could be any fluid that can be reduced (at an appropriate rate) in the chemical reaction that takes place at the cathode.[3].
The fuel cell market is growing. Pike Research estimated that in 2020 stationary fuel cells will be commercialized, all of them reaching a combined power of 50 Gw.[5].
The Japanese automobile manufacturer Honda, the only firm that has obtained approval in Japan and the United States to market its vehicle powered by this system, the FCX Clarity, has also developed the (HES) Home Energy Station") (in:")), an autonomous and domestic system that allows obtaining hydrogen from natural gas to refuel fuel cell vehicles and takes advantage of the process to generate electricity and hot water for the home.
History
Contenido
Aunque parezca algo muy reciente, la historia de las pilas de combustible comenzó hace casi dos siglos, en 1838,[6] con los primeros estudios del científico Christian Friedrich Schönbein en Suiza y, paralelamente, con los del físico y jurista galés Sir William Robert Grove sobre baterías gaseosas, cuyos resultados publicaría en 1843. Hoy en día, se continúa con el empleo de estas células en diversas aplicaciones, tanto portátiles (ejemplo: teléfonos móviles) como estacionarias (ejemplo: generación de energía para edificios), así como en diversos medios de transporte (desde submarinos hasta vehículos particulares). Sin embargo, su desarrollo ha atravesado periodos de olvido, debido a las numerosas dificultades técnicas que presentan en comparación con otros métodos de obtención de electricidad. El interés por las células de combustible, y por tanto su desarrollo, se ha dado en periodos de escasez de recursos energéticos - por ejemplo, la crisis del petróleo de 1973 que precipita el desarrollo de tecnologías alternativas de energía, incluyendo las células de combustible[7] -. Esto se debe a que estas células, comparadas con otros dispositivos, tienen mayor eficiencia energética y por tanto necesitan menos combustible para producir la misma energía.
1843
The figure shows the device presented to the scientific community by William Robert Grove in his publication "On the Gas Voltaic Battery".[8][9] For its preparation, he used two platinum electrodes immersed in sulfuric acid, which he fed with oxygen and hydrogen, respectively. From the dissociation of H2SO4, the reduction took place at the electrode fed with O2 (cathode), which reacted with the H+ ions forming water. Electrons were involved in this reaction, which were generated at the anode during the oxidation of H2, which reacted with the SO42- ion to form sulfuric acid[2]. Grove electrically connected fifty of these cells, generating enough potential to produce the water electrolysis reaction.
1882
The British physicist Lord Rayleigh improved this original configuration. Rayleigh became interested in Grove's work and in 1882 presented a new, more efficient version, due to the increase in the contact surface between the platinum, the reactive gases and the electrolyte.[10].
Ludwig Mond and Charles Langer first used the term "fuel cell" to refer to this type of device. In 1889, these two scientists made a breakthrough, solving the problem associated with the immersion of the electrodes in the liquid electrolyte and therefore, the difficulty of access of the reactive gases to the active points. Its prototype allowed the electrolyte to be retained in a solid non-conductive matrix, whose surface was covered by a thin layer of Platinum or Gold.[10].
1950s and 1960s
In the middle of the century, the technological development of these devices experienced great progress. In 1954, English scientist Francis Thomas Bacon built a 5 kW power plant using an alkaline fuel cell. The cell consisted of a nickel anode, a lithium nickel oxide cathode, and an 85% concentrated potassium hydroxide electrolyte. It was fueled with hydrogen and oxygen.[11] This battery was capable of powering a welding machine. In the 1960s, Bacon's patents (licensed by Pratt and Whitney in the United States - at least the original idea) were used in the United States space program to provide astronauts with electricity and drinking water, from the hydrogen and oxygen available in the spacecraft's tanks.
In 1959, a team led by Harry Ihrig built a 15 kW fuel cell-based tractor for Allis-Chalmers. It was exhibited in the US at state fairs. This system used potassium hydroxide as the electrolyte and compressed hydrogen and oxygen as reactants.[12].
In parallel with Pratt & Whitney Aircraft, General Electric developed the first proton exchange membrane stack (PEMFCs) for NASA's Gemini space missions. The first mission to use PEFCs was Gemini V. However, the Apollo Program missions and the subsequent Apollo-Soyuz, Skylab and shuttle missions used fuel cells based on the Bacon design, developed by Pratt & Whitney Aircraft.[13].
1970s and 1980s
Between 1970 and 1980, as a consequence of the oil crisis and the search for alternative energy technologies, research was carried out on the development of the necessary materials, the identification of optimal fuel sources and the drastic reduction in the cost of the technology associated with fuel cells.
During the 1980s, the use of fuel cells began to be tested in utilities and was also attempted in automobile manufacturing. In the 1990s, large stationary (fixed) fuel cells were developed for commercial and industrial premises.
1993 and 2007
In 1993, the Canadian company Ballard developed the first commercial fuel cell vehicle, using PEM technology.
In 2007, fuel cells are marketed for stationary and auxiliary applications. In 2008, Honda begins sales of a fuel cell-based electric vehicle, FCX Clarity. That same year, the Nobel Prize in Chemistry was awarded to Gerhard Ertl, whose studies revealed how fuel cells work.
Panasonic was the first company in the world to sell the fuel cell for home use. From its launch (May 2009) to September 2013, it sold 31,000 units in Japan.[15].
2013
In 2013, a fuel cell is presented that could represent the transition to affordable batteries. The British company "ACAL Energy" has developed a fuel cell that has achieved a run time of 10,000 hours in fuel cell endurance tests[16] using its FlowCath technology. Unlike a conventional hydrogen fuel cell design, ACAL's FlowCath technology does not rely on platinum as a catalyst, offering a potentially lower cost alternative. It has replaced platinum with a patented liquid catalyst, which acts as a coolant and catalyst for the cells and radically improves the durability of the fuel cell, while reducing the cost of the system.[17].
2014 - Present
The last decade has seen commercial consolidation of the technology and a critical focus on sustainability. Fuel cell vehicles (FCEVs), such as the Toyota Mirai (2014) and Hyundai Nexo (2018), have established a niche market, albeit with modest volumes compared to battery electric vehicles.[18].
The greatest conceptual advance has been the turn towards green hydrogen, produced with renewable energy, recognized as essential for the technology to be truly clean. This has driven national strategies in the EU, Japan and South Korea.[19].
The most promising applications are now in heavy transport. Trucks, city buses and the first fuel cell passenger trains, such as Alstom's Coradia iLint in Germany, are being deployed, replacing diesel fleets on non-electrified lines.[20].
Technology
El funcionamiento de la pila de combustible es similar al de una batería. Se obtiene electricidad a partir de sustancias que reaccionan químicamente entre sí. Sin embargo, mientras que las baterías tienen una capacidad limitada de almacenamiento de energía, la pila de combustible está diseñada para permitir un abastecimiento continuo de los reactivos. Además, los electrodos de la pila de combustible actúan también como catalizadores de las reacciones químicas de oxidación/reducción.
Existen tipos muy distintos de pilas de combustibles. Para explicar su funcionamiento básico, se toma como ejemplo una de las más comunes, la denominada PEM (de membrana de intercambio protónico, en inglés Proton Exchange Membrane). El esquema básico de la celda unitaria de una pila PEM se muestra en la figura de la derecha. Consta de dos electrodos: el ánodo (donde se oxida el combustible) y el cátodo (donde el oxidante o comburente se reduce). El electrolito actúa simultáneamente como aislante eléctrico, conductor protónico y separador de las reacciones que tienen lugar en el cátodo respecto a las que tienen lugar en el ánodo. Debido a lo anterior, los electrones viajan desde el ánodo hasta el cátodo a través de un circuito externo, generando una corriente eléctrica, mientras que los protones lo hacen a través del electrolito. En el cátodo, los electrones, protones y el comburente se reducen, dando lugar a los productos. La reacción es exotérmica y, aunque es espontánea, suele ser muy lenta como para ser operativa sin la presencia de catalizadores. De hecho, lo más común es que los propios electrodos se utilicen como catalizadores. En este tipo de pilas se suele utilizar hidrógeno como agente reductor y oxígeno como oxidante.
Es importante mencionar que, para que los protones puedan atravesar la membrana, esta debe estar convenientemente humidificada, porque la conductividad protónica de las membranas poliméricas utilizadas en este tipo de pilas depende de la humedad de la membrana. Por lo tanto, es habitual humidificar los gases previamente al ingreso a la pila.
Además de hidrógeno puro, también se tiene el hidrógeno contenido en otras moléculas de combustibles incluyendo el diésel, metanol (véase DMFC")) y los hidruros químicos. El residuo producido por este tipo de combustibles además de agua es dióxido de carbono, entre otros.
Las pilas de combustible se pueden clasificar en función del electrolito y del combustible elegido, lo que a su vez determina el tipo de reacciones que se llevarán a cabo en los electrodos y los tipos de iones que la corriente transportará a través del electrolito.
Hoy en día, la mayoría de las células de combustible en desarrollo utilizan hidrógeno o gases sintéticos ricos en hidrógeno. El hidrógeno tiene una alta reactividad y puede obtenerse de formas muy diversas tanto a partir de combustibles fósiles o renovables, como a partir de un proceso electrolítico. Por razones prácticas, el oxidante más común es el oxígeno gaseoso, debido a su alta disponibilidad. Una ventaja de utilizar la combinación de hidrógeno con oxígeno, es que el único producto de la reacción es agua. Por esto, esta combinación es muy utilizada en aplicaciones espaciales. Además, oxígeno y el hidrógeno pueden almacenarse criogénicamente de forma compacta.
La diferencia de potencial generada por una sola unidad o monocelda es inferior a un voltio, por lo que hay que conectar en serie varias mono-pilas para obtener las tensiones adecuadas para las aplicaciones más comunes. Por lo tanto, en la práctica se utilizan sistemas de pilas de combustible.
Strain
The cell voltage depends on the charging current. In open circuit, it is 1.2 volts. To create sufficient voltage, the cells are grouped by combining them in series and parallel, in what in English is called a "Fuel Cell Stack". Generally, more than 45 are used, although they vary depending on the design.
Materials
The materials used in fuel cells vary depending on the type. See Types of fuel cells.
Electrode/bipolar plates are generally made of metal, nickel or carbon nanotubes, and are covered by a catalyst (such as platinum or palladium) to achieve higher efficiency.
The electrolyte can be ceramic or a hybrid polymer electrolyte membrane. This consists of two different polymers. They are arranged in such a way that both constitute a structure where one of the polymers (which is a siloxane polymer) acts as a perforated base so that the other (a polymeric electrolyte) can distribute the perforations in the form of channels.
Design considerations in fuel cells
• - Costs. In 2002, typical cells had a cost due to the catalyst of €850 (approx. 1000 USD) per kilowatt of useful electrical energy; however, it is expected that before 2007, it will be reduced to about €25 (approx. $30) per kilowatt [3]. Using a catalyst enhanced with carbon silk, Ballard has achieved a 30% reduction (1 mg/cm² to 0.7 mg/cm²) in the amount of platinum, without reducing its performance (information from 2005)[4].
• - Water management in PEMFCs. In this type of fuel cell, the membrane must be hydrated, requiring water to evaporate at exactly the same rate as it is produced. If the water evaporates too quickly, the membrane dries out, the resistance across it increases, and 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 evaporates too slowly, the electrodes will flood, preventing the reactants from reaching the catalyst and the reaction will stop. One of the most important objectives in fuel cell research is proper water management.
• - Temperature management. The same temperature must be maintained throughout the cell to avoid destroying the cell due to thermal fatigue.
• - Flow control. As in a combustion engine, a constant ratio between reactant and oxygen must be maintained for the cell to function efficiently.
• - Durability, life, and special requirements for certain cell types. Stationary uses typically require more than 40,000 hours of reliable operation at -35°C to 40°C, while automotive fuel cells require at least 5,000 hours (the equivalent of about 200,000 kilometers) under extreme temperatures. (See: Hydrogen vehicle). Additionally, automotive applications must allow cold starting down to -30°C and have high power per unit volume (typically 2.5 kW per liter).
• - Limited tolerance to CO (carbon monoxide).
Fuel cell systems
Unit cell
The unit cell or mono-cell is the basic element of a fuel cell-based system. The elements that make it up are described below:
• - Electrolyte. It is at the same time ionic conductor, electrical insulator and separator of the cathode and anode. Depending on the state of aggregation of the electrolyte, we can find two types of fuel. Thus, according to Appleby and Foulkes,[21] we have:
Liquid electrolyte fuel cells. In this type, the electrodes are porous and the electrolyte is in contact with them, soaking small areas. The gaseous reactants diffuse through a thin layer of electrolyte and react electrochemically on the electrode surfaces. The amount of electrolyte that the electrode can contain is limited. Therefore, an excess of liquid could prevent the transport of gaseous species and also the reactions necessary to obtain energy.
Solid electrolyte fuel cells. This type contains a high number of catalysts at the interface, which must be electrically and ionically connected to the electrodes and the electrolyte respectively, and which are also efficiently exposed to the gaseous reagents.
• - Electrodes. Electrochemical reactions take place on the surface of the electrodes. Fuel is oxidized at the anode and oxygen is reduced at the cathode. The electrodes are usually porous, to allow gaseous diffusion (although there are some non-porous ones[22]). In this way, good contact can be established between the three phases that participate in the reaction (the solid phase of the electrode, the gaseous phase of the fuel, and the liquid or solid phase of the electrolyte). The main functions of the electrodes are:
Conduct or dislodge ions from the ternary interface.
Ensure that the gaseous reactants are evenly distributed in the electrolyte.
Ensure that the reaction products are efficiently carried into the gas phase.
Stacks
Since the potential difference generated by a single fuel cell is small (approximately 0.7 volts), in practice several are combined in series to achieve the appropriate output voltage for the desired application. Logically, the interconnections between the unit cells are made using materials with high electrical conductivity. Among the numerous types of possible stacks, the most common are those with a flat structure, although there are also tubular ones.
In flat structure stacks, elements known as "bipolar plates" are normally included (see Fuel Cells (animations)). They consist of two separator plates located at the ends of the system. through which connections are made. One acts as an anode and another as a cathode. Additionally, these plates separate the fuel and oxidant from adjacent cells, in turn providing an excellent means for supplying these reactants. In many designs, the plates include channels (see figure to the right) that allow uniform distribution of gas flow over the cells. This design is quite simple electrically: the path that the electric current travels is relatively short and, therefore, offers little resistance to the passage of electrons, and consequently little voltage drop.
Another type of stacking, especially indicated for fuel cells that work at high temperatures (such as solid oxide-SOFC), consists of a tubular configuration (figure on the left). These types of batteries usually use a solid ceramic material, such as zirconium oxide stabilized with yttrium oxide, as the electrolyte, instead of a liquid or an exchange membrane.
Systems based on fuel cells
While the fuel cell itself is the key component, a fuel cell-based system must include other subsystems and components, known as balance of plant (BOP). A fuel cell-based system is then formed by a stack of fuel cells and a BOP, properly combined.
There is a wide variety of configurations for this type of system. Indeed, the precise composition and arrangement of the BOP elements depends largely on the type of fuel cell, the operating temperature, the fuel chosen and the application for which it is used. Additionally, the specific operating conditions and requirements of the individual cell and stack design determine the characteristics of the BOP.
However, even taking into account the diversity and flexibility of these systems, it is advisable to show at least one example of the components (or stages) that make up a system based on fuel cells. The figure shows a schematic of a generic system based on fuel cells. As can be seen, in the first stage, the fuel (hydrogen, natural gas, methane, etc.) is introduced into the reformer in which, through a chemical transformation, a gas rich in hydrogen known as "reformed" is produced and as a by-product, carbon monoxide with a concentration level of less than 50 ppm.
The next stage takes place in the gas purification system, where any impurities that the reformed product may have are eliminated. Once the hydrogen is purified, it is ready to be introduced into the fuel cell. In this stage, electrical energy is generated through the electrochemical reaction with oxygen. The heat generated in the reaction can be used to preheat the fuel. In the case of fuel cells that operate at high temperatures (between 600-1000 °C), the heat generated could be invested in cogeneration, that is, it can be used to drive gas turbines and generate more electricity, for desulfurization units, generation of chemical products, etc.[23].
Types of fuel cells
Actualmente existe una gran variedad de pilas de combustible en diferentes etapas de desarrollo. Por ello, se pueden clasificar atendiendo a numerosas características. Las más comunes son las siguientes:[24].
Según el tipo de combinación de combustible y oxidante. Los combustibles típicos son el hidrógeno molecular y el metanol, y normalmente oxígeno o aire como oxidante. Pero como se ha visto en la figura 2.4, se pueden alimentar con una amplia variedad de combustibles, como hidrógeno, metanol, biomasa, gasolina, carbón, etc.
Según el tipo de electrolito usado. Por ejemplo: ácido fosfórico, membrana de polímero sólido, solución alcalina, etc.
Según la temperatura de operación. Por un lado, tenemos pilas de combustible de baja o media temperatura (con temperaturas inferiores a 200 °C), como las PEM, las AFC y las PAFC. Por otro, las de alta temperatura, que sobrepasan los 600 °C, como las MCFC y las SOFC. Según la fuente que se consulte, los rangos son ligeramente distintos, por lo que esta clasificación no es estricta.
Según su eficiencia. En este caso, el rango es distinto dependiendo del tipo de pila y del tipo de aplicación en la que se utilice. Por ejemplo, para una PEM tiene una eficiencia en torno a un 40%[24] en aplicaciones estacionarias y en torno a un 60% en aplicaciones para el transporte.
Según el tipo de uso. Aplicaciones portátiles, estacionarias, de transporte, militares, espaciales, etc.
Según su potencia. Pilas de baja potencia (alrededor de 5 kW en el caso de las DMFC, por ejemplo) y de alta potencia (100 kW a 2 MW en las SOFC, por ejemplo).[25].
Según el catalizador utilizado. Típicamente, platino, metales no preciosos o el propio material de los electrodos. También pueden ser de paladio.[26].
La forma más usual de clasificación es por el tipo de electrolito que utilizan. Se pueden entonces establecer,[24] cinco tipos principales de pilas, que se describen a continuación.
Proton Exchange Membrane (PEM) Fuel Cell
• - Electrolyte: solid polymer membrane.
• - Catalyst: platinum.
• - Operating temperature: around 80-95 °C.
• - Electrical efficiency: 40-60%.
PEMs operate at relatively low temperatures, have high power density, and can rapidly vary their power output to adapt to energy demand. There are PEMs with powers that vary between a few watts and several kilowatts, so they can be used in a multitude of systems. Thus, until 2013 the maximum power achieved with a stationary power plant (fixed energy installation) type PEM is 1 MW, and was installed by the Japanese company Honda[6].
PEM type fuel cell systems are suitable for applications requiring rapid operating response. Thus, they are used in a wide variety of systems that focus on the telecommunications market (both industrial and home) and in vehicles for transporting materials, such as forklifts. They are also used in buses and it is expected that between 2014-2016 passenger vehicles (passenger cars like the one shown in the figure) from PEM can be marketed. PEMs can use hydrogen, methanol or reformed fuels as fuel.
In PEMs, the electrolyte is a solid polymer membrane containing perfluorinated sulfonic acids, and must be kept fully hydrated during operation to promote proton conduction. This requirement limits the operating temperature to below 100 °C and is essential to obtain good efficiency. Since water is the only liquid used, corrosion problems are minimal.[25].
The main current challenges in the development of this type of batteries are: reducing cost and increasing efficiency (which translates into reducing the thickness of the platinum catalytic layer and optimizing the dispersion of the catalyst); improve the performance of the polymeric membrane (increase ionic conductivity and water retention capacity); and find an alternative material to graphite for the bipolar plate that is high in electrical and thermal conductivity, resistant to corrosion, lighter and cheaper.[25].
High-temperature proton exchange membrane (High-temperature PEM or HT-PEM).
HT-PEMs are, in essence, PEMs that can operate at high temperatures, between 120 °C and 200 °C. They are usually used in vehicles and, less commonly, to supply energy to buildings. HT-PEMs often integrate a reformer (that is, a device capable of reforming fossil fuels or alcohols into synthetic gas consisting mainly of hydrogen and carbon monoxide), which allows them to be fed with a greater variety of fuels.
Methanol Fuel Cell (DMFC)
• - Electrolyte: solid polymer membrane.
• - Catalyst: Platinum.
• - Operating temperature: around 50-120 °C.
• - Electrical efficiency: above 40%.
Like PEMs, DMFCs use a polymer membrane as electrolyte. However, in DMFC systems it is not necessary for the fuel to pass through a reformer, since the catalyst anode itself extracts hydrogen from liquid methanol. Since the minimum operating temperature of this type of battery is low, DMFC can be used in small applications, such as mobile phones (see figure on the right), laptop computers and battery chargers for other electronic products [7] Archived on July 14 2014 on the Wayback Machine., and also in medium-sized applications to power the electronics of boats or cabins.
In this type of batteries, the challenge is to find a membrane that allows working at temperatures above 130 °C and that does not present "crossover" problems (passage of the anodic reactant to the cathode compartment through the membrane) and to find a more active anodic catalyst for the direct oxidation of methanol.[25].
Alkaline Fuel Cells (AFC)
• - Electrolyte: a solution of potassium hydroxide in water.
• - Catalyst: a wide variety of non-precious metals can be used.
• - Operating temperature: between 105-245⁰C.
• - Electrical efficiency: 60-70%.
The fuel and oxidizer used in AFCs must be pure hydrogen and oxygen. Indeed, CO2 (or CO) reacts with KOH and potassium carbonate is formed, which greatly reduces the efficiency of the fuel cell.[25] Even with small concentrations (10 to 100 ppm) "poisoning" of the cell by carbon monoxide or dioxide occurs.[27] For this reason, they are mainly used in the aerospace sector and underwater environments, figure 2.15.
The electrolyte concentration is around 35-50% for operating temperatures below 120 °C, and can operate at 250 °C when the concentration is 85%.[25].
These batteries are the ones that offer the highest performance. It is one of the reasons why they are used in space exploration, since the fuel must be put into orbit and the mass to be lifted has to be optimal. NASA has used hydrogen-powered AFCs on space missions since 1960 to provide electricity and drinking water.[28].
Phosphoric Acid Fuel Cell (PAFC)
• - Electrolyte: Liquid phosphoric acid.
• - Catalyst: Platinum based on carbon.
• - Operating temperature: between 180-205⁰C.
• - Electrical efficiency: 36-42%.
PAFCs can use hydrocarbons or biogas as fuel. The reactions at the cathode and anode are similar to those that occur in PEMs, but the operating temperature is higher and they also tolerate impurities that the fuel may have better.
PAFCs are frequently used in cogeneration. Today, the commercialization of PAFCs is widespread. They are frequently used to provide electricity to buildings with high energy demand, both public and private.
In 1991, UTC put the first power generation plant based on this fuel cell technology on the market. The PureCell power system, see figure, supplies 200 kW of power and about 850 J of energy every hour. The accumulated operating time for all units sold exceeds 6 million hours.[25].
Molten Carbonate Fuel Cell (MCFC)
• - Electrolyte: alkaline carbonates on a ceramic matrix.
• - Catalyst: from the electrodes (not platinum).
• - Operating temperature: around 650 °C.
• - Electrical efficiency: 50-60%.
In this type of cells, the high operating temperature allows the internal reforming of the fuel, that is, the conversion of fuel to hydrogen is done within the cell itself. Since MCFCs are not prone to contamination with CO or CO2, they can even use carbon oxides as fuel, something that makes them especially suitable for feeding them with gases from coal. MCFCs are used in stationary applications and in cogeneration, to provide energy to public or private buildings.
This technology has been in development for a long time. The following link shows a photo of a 100 W power system based on MCFC technology and manufactured by Texas Instruments in 1966. The greatest exponents in the development of this technology have been the German MTU, and its American partner, Fuel Cell Energy.[25].
Solid Oxide Fuel Cell (SOFC)
• - Electrolyte: ceramic solid or non-porous metal oxide.
• - Catalyst: electrode material (not platinum).
• - Operating temperature: 800-1000 °C.
• - Electrical efficiency: 50-60%.
These types of high-temperature cells are designed to reform light hydrocarbons (such as natural gas) internally. Therefore, if heavier hydrocarbons (such as gasoline) were to be used, an external reformer would be required.
Its shape can be flat or tubular. These types of batteries are used in a long list of stationary applications throughout the world.[29].
Given that these types of batteries currently operate between 800-1000 °C, the challenge is to go down to 600-800 °C (IT-SOFC, "Intermediate Temperature Solid Oxide Fuel Cell"). Research focuses on reducing the thickness of the electrolyte layer and on the search for new materials, based on lanthanide oxides or with a perovskite structure, that present high ionic conductivity at low temperature.[25].
Comparison between the different types
As a summary, the following table compares the main types of fuel cell in Marketing/research status.
Other types of fuel cells
The following table presents other types of fuel cells that are based on the main types, but that have their own characteristics that make them interesting for both general and specific applications.
Behavior
The Gibbs function and the Nernst potential
In a fuel cell, an electrochemical reaction occurs at constant temperature and pressure that will never reach equilibrium. The work that can be obtained under these conditions is called non-expansion work[30] and its maximum value coincides with the Gibbs free energy variation. In the case of an electrochemical reaction, this work is the electrical energy necessary to release the electrons, W, and is given by the change in the Gibbs function, ΔG, of the chemical reaction (it is also called reaction free energy):[30].
This expression is particularly useful for evaluating the electrical work that occurs in fuel cells and electrochemical cells. The electrical work is obtained by taking into account the number n of electrons released by each molecule produced in the chemical reaction, and the potential difference E that they acquire when released. This work is equal to –neE, e being the charge of the electron. If we want to express the reaction per mole instead of per molecule, we will have to multiply n by Avogadro's number, which will give us nN electrons for each mole produced. Therefore, the work associated with the generation of nN electrons, with a potential difference E, is:[24].
The product eN, which is the electric charge of one mole of electrons, is called Faraday's constant and is designated by the letter F. Therefore:.
being .[31].
The potential E is known as the Nernst potential[24] and gives the electrical voltage that can be obtained when an electrochemical reaction occurs reversibly. This potential is also known as electromotive force and is the one obtained under open circuit conditions, that is, in the absence of electric current.
It is usual to find the reaction free energy, or the data necessary to calculate it, (such as enthalpies and entropies) tabulated for the standard state "Standard conditions (chemistry)") of T = 298.15 K and P = 1 atm.[32] Said reaction energy in the standard state is denoted as ΔG. For a reaction that does not occur under these standard conditions it can be written [32].
where Q is the reaction quotient.
Dividing the previous equation by nF we obtain the so-called Nernst Equation:.
where E is known as the standard cell potential, which is nothing more than the standard Gibbs reaction energy expressed in Volts.
As in fuel cells it is normal to have the reactants and products in a gaseous state, then Q is obtained from the partial pressures:[24][30].
where ν and ν are the stoichiometric coefficients of the chemical reaction. So Nernst's potential in this case will be:
The Nernst potential is the equivalent of the “electromotive force” or “cell potential” of a battery, which is the potential difference observed in an open-circuit battery.
Performance
The ideal performance or efficiency of the chemical to electrical conversion is defined as the quotient between the electrical energy obtained in the case in which the current is infinitely small, W or as we saw in the first section of this section, ΔG, and the chemical energy put into play ∆H, we can write it as:.
As an example, the calculation of the ideal performance under standard conditions (T=298.15 K and P = 1 atm), η, can be made for a cell based on the reaction of hydrogen with oxygen:.
where the water produced is liquid. Under these conditions:[24].
therefore,.
For other electrochemical reactions the procedure would be analogous.
The performance of fuel cells, unlike combustion engines (internal and external), is not limited by the Carnot cycle since they do not follow a thermodynamic cycle. Therefore, its performance is very high in comparison, converting chemical energy into electrical energy directly.
The potential difference across the cell's electrodes decreases when current exists. For convenience, the performance of a fuel cell is often expressed in terms of the ratio between the ideal voltage and the actual voltage (at which the fuel cell operates), the latter being lower than the former due to ohmic losses and those associated with polarization mechanisms within the cell. The expression of the efficiency of the fuel cell is as follows:.
where V is the voltage measured between the electrodes in real operating conditions, and I is the current intensity that circulates through the external circuit. This efficiency is also known as voltage efficiency.[33] In this expression it is considered that all the fuel is being used, since this is the case in most combustion engines. However, in fuel cells the complete conversion of fuel is not usually carried out and it is necessary, to calculate the efficiency in real voltage, to multiply the previous equation by a factor that indicates how much fuel is being used.
Therefore, although the ideal performance seems very high, it is reduced by actual operating conditions.
A fuel cell typically converts the chemical energy of fuel into electricity with an efficiency of approximately 50%. The performance however depends largely on the current flowing through the fuel cell: the higher the current, the lower the performance.
Losses due to production, transportation and storage must also be considered. Fuel cell vehicles running on compressed hydrogen have an efficiency of 22% if the hydrogen is stored as a high-pressure gas, and 17% if it is stored as liquid hydrogen (these figures should justify your calculation methodology).
Fuel cells cannot store energy like a battery, but in some uses, such as stand-alone power plants based on "discontinuous" sources (solar, wind energy), they are combined with electrolyzers and storage systems to form an assembly to store this energy. The efficiency of the reversible process (from electricity to hydrogen and back to electricity) of such plants is between 30 and 40%.
Actual behavior
As indicated in previous sections, the Nernst potential gives the “electromotive force” of the fuel cell, that is, the potential difference between its electrodes in the absence of electric current. Once the circuit is closed and current begins to flow, potential losses appear related to charge conduction within the electrolyte and polarization phenomena. As a consequence, the potential difference measured between the electrodes is less than the ideal (Nernst potential) calculated in the previous section.
To clearly visualize the difference between both potentials, the potential is usually represented against the current density, giving rise to the so-called operating curve, also called polarization curve. This curve, as shown in the figure on the right, presents three main regions of operation.
As shown in parentheses, each of the regions shown in the previous graph has an associated source of efficiency loss:[24].
• - Activation losses: due to the low rate of reactions in the activation polarization region.
• - Ohmic (resistive) losses: related to the flow of electrons through the electrode material, as well as the resistance to the flow of ions through the electrolyte in the ohmic polarization region.
• - Concentration losses: changes in gas concentration or mass transport in the polarization region due to concentration.
Below we will see in more detail the types of losses mentioned.
These types of losses are due to the slowness of the reactions in the electrodes. For electrochemical reactions to begin, as in common chemical reactions, the reactants must exceed the activation energy. In reality, not a single reaction occurs in the electrodes but several, each with its own speed and activation energy. Thus, activation losses are the result of the losses due to each of these successive reactions.
Activation losses are expressed mathematically by the Tafel equation"):[34].
R≡ideal gas constant measured in J/molK.
T≡operating temperature in K.
α≡electron transport coefficient (dimensionalless).
n≡number of electrons per molecule (dimensionalless).
F≡Faraday constant in C/mol.
i≡current generated in A.
i≡exchange current (depends on the type of material), measured in A.
This equation is valid for values of ΔE≥(50-100)mV.[34].
According to Barbir[35] the factors that reduce activation losses are:
• - Increase in operating temperature.
• - Effective catalysts.
• - Use of pure oxygen as an oxidizing agent instead of air.
Variables that affect operation
The output potential of fuel cells is affected by the operating conditions (temperature, pressure, gas composition, use of reagents, current density), by the design of the cell and by other factors (impurities, durability of the device) that cause it to move away from the ideal value previously calculated. For more information about this type of losses, consult the following references.[24][35][37][38].
Fuel cell applications
Energy
Fuel cells are very useful as power sources in remote locations, such as spacecraft, remote weather stations, large parks, rural locations, and in certain military uses. A fuel cell system that runs on hydrogen can be compact, lightweight, and have no major moving parts. Because fuel cells have no moving parts and do not involve combustion, under ideal conditions they can reach up to 99.9999% reliability.[39] This is equivalent to less than one minute of downtime over a six-year period.[39].
Cogeneration applications (combined use of heat and electricity) for homes, office buildings and factories. This type of system generates electrical energy constantly (selling excess energy to the grid when it is not consumed), and at the same time produces air and hot water thanks to the heat it gives off. Phosphoric-Acid Fuel Cells (PAFC) comprise the largest segment of cogeneration applications worldwide and can provide combined efficiencies close to 80% (45-50% electrical + the rest as thermal). The largest manufacturer of PAFC fuel cells is UTC Power", a division of United Technologies Corporation. Molten Carbonate Fuel Cells (MCFCs) are also used for identical purposes, and prototypes of Solid-Oxide Fuel Cells (SOFCs) exist.
Electrolyzer systems do not store fuel themselves, so they require external storage units, which is why they are usually used in rural areas.[40] In this case, the batteries have to be large in size to meet the storage demand, but this still represents savings compared to conventional electrical devices.
There are many different types of stationary fuel cells so efficiencies vary, but most are between 40% and 60% energy efficient.[41] However, when waste heat from the fuel cell is used to heat a building in a cogeneration system this efficiency can increase to 85%,[41] i.e. almost three times more efficient than traditional coal plants.[42] Therefore, in large-scale production, fuel cells could save 20-40% in energy costs when used in cogeneration systems.[43] Fuel cells are much cleaner than traditional power plants; A fuel cell-based power plant using natural gas as a hydrogen source could generate less than one ounce (approximately 28.35 grams) of pollutants (other than CO2), for each kW/h produced, while conventional combustion systems would generate 25 ounces (708 grams).[44].
There is an experimental program on Stuart Island in Washington state,[45] where the Stuart Island Energy Initiative company has built a complete system in which solar panels generate the current to operate several electrolyzers that produce hydrogen. Said hydrogen is stored in a 1900 liter tank, at a pressure of 10 to 80 bar. This fuel is ultimately used to power a ReliOn brand 48V hydrogen fuel cell that provides enough electrical power for residential purposes on the island (see link external to SIEI.ORG). Another system of this type was installed in 2011 Hempstead, NY.[46].
Fuel cells can be used with low-quality gas from landfills or wastewater treatment plants to generate energy and reduce methane emissions. The largest fuel cell-based power plant is a 2.8 MW plant located in California.[47].
Protium, a rock band formed at Ponaganset High School in Glocester, was the first musical group in the world to use hydrogen fuel cells to provide energy. The band used a 1kW Ballard Power systems Airgen Fuelcell. The ensemble has played at numerous fuel cell related events including the CEP in Connecticut, and the 2003 Fuel Cell Seminar in Miami Beach.
Plug Power Inc. is another major company in the design, development and manufacturing of PEM fuel cells for stationary applications, including products aimed at telecommunications, basic power, and cogeneration applications.
Cogeneration
Combined fuel cell heat and power (CHP) systems, including micro combined heat and power (MicroCHP) systems, are used to provide heat and power to homes, office buildings and factories. These systems constantly generate electrical energy (selling excess to the grid when not consumed) and, at the same time, produce hot air and water with waste heat. As a result CHP systems have the potential to save primary energy as they can make use of waste heat, which is normally rejected by thermal energy conversion systems.[48] The typical power range of a domestic fuel cell is 1–3 kWel / 4–8 kWth.[49][50] CHP systems connected to absorption chillers use waste heat for cooling.[51].
The waste heat from the fuel cells can be diverted in summer directly to the ground for additional cooling while in winter the waste heat can be pumped directly into the building. The University of Minnesota owns the patent rights for this type of systems.[52][53].
Cogeneration systems can reach 85% efficiency (40-60% electrical and the rest thermal).[41] Phosphoric acid fuel cells (PAFC) are the most widely used in CHP products in the world and can achieve combined efficiencies close to 90%.[54][55] Molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC) are also used for combined heat and power production systems and They have an electrical efficiency close to 60%.[56] The disadvantages of these cogeneration systems include high costs and short duration.[57][58] In addition, their need to have a tank to store hot water to soften heat production represents a serious problem for the domestic market since space in homes represents a great cost.[59].
Fuel cell vehicles
Although there are currently no fuel cell-equipped vehicles available for large-scale sale, more than 20 fuel cell vehicle (FECV) prototypes and demonstration cars have been launched since 2009. Demonstration models include the Honda FCX Clarity, Toyota FCHV, Fiat Phyllis and Mercedes-Benz F-Cell.[60] Since 2011, FECV demonstration cars have traveled more than 4,800,000 km, with more than 27,000 recharges.[61] A range of 400 km between recharges has been achieved.[62] They can also be recharged in less than 5 minutes.[63] The Fuel Cell Technology Program of the US Department of Energy ensures that, as of 2011, fuel cells are achieving an efficiency between 53% and 59% at a quarter of its power and between 42% and 53% at full power[64] with a durability of 120,000 km with a degradation of less than 10%.[62] In a complete "well-to-wheel" analysis), which does not take into account economic or market restrictions, General Motors and its partners estimated that, per mile traveled, a vehicle powered by compressed gaseous hydrogen used about one 40% less energy and emitted 45% less greenhouse gases than an internal combustion vehicle.[65] A chief engineer at the Department of Energy whose team is testing fuel cell cars said in 2011 “that their attractive potential lies in the fact that they are fully functional vehicles with no recharging limit and therefore are a direct replacement for any vehicle. For example, if you are driving a maximum-size SUV and want to drag a boat up the mountain, it can be done with this technology and it cannot be done with current vehicles that run only on batteries, which are more designed for urban driving.”[66].
Some experts believe, however, that fuel cell cars will never become economically competitive with other technologies[67][68] or that it will take decades until they become profitable.[69][70] In July 2011, General Motors Chairman and CEO Daniel Akerson said: “The car is still too expensive and probably won't be practical until later in 2020, I don't know” although fuel cell car prices of hydrogen fuel were decreasing.[71].
In 2012, Lux Research, Inc., published an article stating: “The dream of a hydrogen economy…is no closer.” It concluded by saying: “The cost of capital… will limit its adoption to no more than 5.9 GW” in 2030 with an almost “insurmountable barrier to adoption except in very limited market areas.” The analysis concluded by saying that in 2030 the stationary PEM market would reach one trillion dollars while the market for vehicles, including forklifts, a total of two trillion.[72] Other analyzes cite the lack of an extensive hydrogen infrastructure in United States as a challenge for the commercialization of electric fuel cell vehicles. In 2006, a study for IEEE showed that, for hydrogen produced by the electrolysis of water: "Approximately, only 25% of wind, hydro or solar energy has practical use." The study, later, mentioned that: "it appears that the energy obtained from hydrogen fuel cells is four times more expensive than the energy obtained from the grid... Because the high energy losses (hydrogen) cannot compete with electricity" (95). Furthermore, the study stated: The modification of natural gas is not a sustainable solution.”[73] The large amount of energy needed to isolate hydrogen from other natural components (water, natural gas, biomass), store the gas by compression or liquefaction, transfer the energy to the user, plus the loss of energy when it is converted into usable electrical energy through fuel cells leaves around 25% for practical use.[74][75][76].
Portable power systems
Portable power systems based on fuel cells can be used in the leisure sector (e.g. caravans, cabins, boats), the industrial sector (e.g. to power remote gas or oil wells, communication towers, security, weather stations, etc.) and the military sector.[126][127].
Other possible uses
• - Base power plants").
• - Auxiliary Energy Systems[128].
• - Provide power for base radio stations[129].
• - Energy centralization systems").
• - Emergency power systems"), which include lighting, generators and other devices that provide support in critical situations or when normal systems fail. They can be used in many places, from homes to hospitals, research centers and data centers.[130].
• - Telecommunications equipment and modern naval equipment.[131].
• - Uninterruptible power supply system UPS (uninterruptible power supply), provides power in case of emergency and, depending on the topology, regulates the line in addition to the equipment providing power from a separate source when the other is not available. Unlike a standby generator, it provides instant protection against a momentary line interruption.
• - Solar hydrogen fuel cells for water heating.[132].
• - Hybrid vehicles, using, for example, a fuel cell and a battery.
• - Support systems for the electrical network.
• - Portable ports for small electronic instruments (e.g., a belt clip that charges your cell phone or PDA).
• - Smartphones, laptops and tablets.
• - Small heating devices[133].
• - Food preservation, achieved by eliminating oxygen and automatically maintaining the absence of oxygen in a container containing, for example, fresh fish.
• - Breathalyzers, where the voltage generated by the battery is used to determine the concentration of fuel in the sample (alcohol)[134].
Currently, the biggest problems lie in the support and catalysis materials. According to various authors (Venkatachalapathy, Davila et al. 1999), (Hoogers 2003), an electrocatalyst material must satisfy several requirements. It needs, first of all, high efficiency in the electrochemical oxidation of the fuel at the anode, (e.g. H or CH) and for the reduction of O at the cathode. High durability is also a fundamental requirement: PEMFCs are expected to operate for at least 10,000 hours. It is necessary for an electrocatalyst to have good electrical conductivity to minimize resistance losses in the catalyst layer. It must finally have a low production cost.
Economy and Environment
In 2012, fuel cell industry revenues surpassed $1 trillion on the stock market worldwide.[135] However, as late as October 2013, no public company in the industry was yet profitable.[136]140,000 fuel cell stacks were shipped globally in 2010, 11,000 more than in 2007, and since From 2011 to 2012 the shipment growth rate was 85%.[137] Tanaka Kikinzoku Kogyo K.K") increased its facilities for the production of fuel cell catalysts to respond to anticipated demand as Japanese ENE Farm expected to install 50,000 units in 2013[138] and the company is experiencing rapid market growth.
About 50% of fuel cell shipments in 2010 were fuel cells, up from one-third in 2009, and the four dominant producers in the Fuel Cell Industry were the United States, Germany, Japan, and South Korea.[139] The Department of Solid State Energy and the Energy Conversion Alliance found that, as of June 2011, stationary fuel cells generated power at a price of $774 – $775 per installed kilowatt.[140] In 2011, Bloom Energy, a large fuel cell supplier, said its fuel cells generated power at 9-11 cents per kilowatt-hour, including the price of fuel, maintenance and equipment.[141].
Industry groups predict that there are sufficient reserves of platinum for future demand,[142] and in 2007, research conducted at Brookhaven National Laboratory suggested that platinum could be replaced by a coating of gold and palladium, which could be less susceptible to poisoning and therefore lengthen the life of the fuel cell.[143] Another approach could be to use iron and sulfur instead of platinum. This would lower the cost of the batteries (since the platinum in a typical fuel cell costs around US$1,500 and the required iron would cost US$1.50). The concept was being developed by a coalition formed by the John Innes Center and the University of Milan-Bicocca").[144] PEDOT cathodes are immune to monoxide poisoning.[145].
Fuel cells are very attractive for advanced uses due to their high efficiency and ideally (see renewable energies) because they have zero emissions, in contrast to the most common current fuels, such as methane or natural gas, which always generate carbon dioxide. Almost 50% of all electricity produced in the United States comes from coal, which is a highly dirty energy source. If electrolysis is used to create hydrogen using energy from power plants, hydrogen is actually created from coal. Although the fuel cell only emits heat and water as waste, the pollution problem will continue to be present in power plants.
A global approach must consider the impacts caused by the entire hydrogen scenario, including production, use, infrastructure and energy converters. Fuel cells today are oversized with catalyst, to compensate for their own deterioration [8]. The limitation in platinum mineral reserves has led to the search for other solutions, for example the synthesis of an inorganic complex very similar to the iron-sulfide catalytic base of hydrogenase bacteria [9]. The world's platinum reserves would be insufficient (one quarter) of what is needed to allow a complete conversion of vehicles to fuel cells: a significant introduction of vehicles with current technology would therefore cause a large increase in the price of platinum and a significant decrease in its reserves. However, recent work has managed to design iron and nitrogen catalysts as efficient as platinum ones, but with a shorter useful life (100 hours) [10].
Glossary of terms
• - Electrode: End of a conductive body in contact with a medium from which it receives or to which it transmits an electric current[146].
• - Anode: Electrode in which oxidation occurs. For fuel cells and other galvanic cells the anode is the negative terminal; For electrolytic cells (in which electrolysis occurs) the anode is the positive terminal.[147].
• - Cathode: Electrode in which the reduction (gain of electrons) occurs. For fuel cells and other galvanic cells the cathode is the positive terminal; For electrolytic batteries the cathode is the negative terminal.[147].
• - Electrolyte: A substance that conducts charged ions from one electrode to another in a fuel cell, battery, or electrolyzer.[147].
• - Stacking: Individual fuel cells connected in series. Fuel cells are stacked to increase voltage.[147].
• - Solution: A: a process by which a solid, liquid, or gaseous substance is mixed homogeneously with a liquid or, sometimes with a gas or with a solid; B: a homogeneous mixture formed by this process; C: the condition of being dissolved[148].
• - Catalyst: A chemical substance that increases the speed of a reaction without being consumed.[147].
• - Matrix: place from which or within which something originates, develops or takes shape.[149].
• - Membrane&action=edit&redlink=1 "Membrane (selective barrier) (not yet drafted)"): The separation layer in a fuel cell that acts as an electrolyte and as a barrier film that separates gases in the anodic and cathodic compartments of the fuel cell.[147].
Videos about fuel cells
En esta sección se resumirán los principales aspectos referidos a treinta y cinco videos seleccionados y se hará breve una reseña de los mismos. La selección se ha centrado en videos de carácter divulgativo y sobre todo, en los que tratan los aspectos científicos y técnicos de las pilas de combustible. Sin embargo, con el fin de complementar el rigor científico de los otros videos, también se han seleccionado videos cuyas explicaciones son escuetas pero que nos ofrecen una perspectiva visual del dispositivo que estamos tratando y de sus aplicaciones. La lista consta de 11 videos en español y 24 en inglés. El enlace directo a la lista de reproducción es el siguiente:.
Pilas de Combustible.
Videos in Spanish
1º Fuel cells..
• - Direct link.
• - Author: University of Vigo, Prof. Anxo Sánchez Bermúdez.
• - Duration: 19:55 minutes.
• - Description: introduction to fuel cells. It clearly defines this type of device and talks about its different aspects in a general way and without delving into details. However, it must be taken into account that when talking about the characteristics, advantages and disadvantages, he is mainly referring to the hydrogen fuel cell. It is therefore a video of an informative nature and very useful for a first approach to the subject.
2nd Video Series: Hydrogen Energy..
• - Direct link.
• - Author: Polytechnic University of Madrid, made by students.
• - Duration: 1:58 hours.
• - Description: these are nine presentations made by UPM students about hydrogen fuel cells and their different applications; Each presentation focuses on a different aspect. The interest of these videos lies in the fact that they show and analyze a large number of applications that these devices can have. Although they focus on specific aspects and applications, they can generally be understandable for the non-specialized public since very technical details are not usually presented and some of the presentations begin with a short introduction about fuel cells. Below is a description of each of the videos that make up the series:
Stationary applications of the various types of fuel cells: The main characteristics of the different types of fuel cells and their applications in stationary power generation are described.
Automotive applications: The prototypes manufactured by different automobile companies are described: the state of the commercial implementation of automobiles powered by fuel cells is presented.
Portable applications of fuel cells: The choice of fuel in the case of fuel cells used in portable applications is discussed and some prototypes are shown.
Use of hydrogen in aerospace vehicles 1: The scope of application and use of fuel cells in space shuttles and manned and unmanned aircraft is explained.
Use of hydrogen in aerospace vehicles 2: Continues where the previous video ends, complementing it. The types of propulsion of aerospace vehicles using hydrogen are explained: fuel cells, internal combustion engines and hybrid systems. The "Aviazor Project" is detailed.
Projects that develop propulsion of aerospace vehicles with hydrogen: The theme of video 5 continues, describing the different stages and characteristics of the projects, some projects such as: "Ion Tiger", "Solareagle", "Phantom Eye" and "Global Observer".
Applications of fuel cells in the marine environment: An overview is given of what a fuel cell is, its classification and its main advantages. A brief overview of the possible applications of the different types of fuel cells in the marine environment is offered.
Applications of fuel cells in underwater devices: Existing submarines that have fuel cells in their propulsion are described. It explains what an AIP (Air Independent Propulsion) system is. In particular, the S-80 submarine is explained, which will use hydrogen from reformed bioethanol to power PEMFC fuel cells. Unmanned autonomous underwater devices are also described.
Applications of fuel cells in surface ships: Surface vessel projects that incorporate fuel cells in their main propulsion system or to meet electrical consumption or as auxiliary power units are described. The effect of reducing emissions as a consequence of the use of fuel cells in the marine world is studied.
3rd Hydrogen cell..
• - Direct link.
• - Author: Tecnópolis. Presented by Vicente López.
• - Duration: 1:40 minutes.
• - Description: Brief but concise explanation about the hydrogen fuel cell vehicle and the viability of hydrogen as an energy vector, highlighting the environmental advantages of its use.
• - Direct link.
4º Buses with fuel cells..
• - Direct link.
• - Author: CEER Courses.
• - Duration: 1:53 minutes.
• - Description: dynamic explanation with figures and text about the operation of a PEM type fuel cell. The main components are described and their specific location in the stack is shown. Finally, its application is seen in a transport vehicle (bus).
5º Produce electricity through plants..
• - Direct link.
• - Author: Euronews.
• - Duration: 1:58 minutes.
• - Description: This video shows how green plants generate electricity. This is the Plant-e project of Wageningen University in the Netherlands. The microbial plant fuel cell generates electricity from the natural interaction between plant roots and soil bacteria. It works by taking advantage of up to 70% of organic material produced through photosynthesis that is not used by the plant and is secreted by the roots. The bacteria that are next to the roots interact with the organic waste, releasing electrons. And this is how electricity is generated: by placing an electrode that absorbs the released electrons.
6º Fuel cells..
• - Direct link.
• - Author: Polytechnic University of Valencia, Javier Orozco Messana.
• - Duration: 11:01 minutes.
• - Description: This is an introduction to fuel cells. It starts with a brief definition. Continue with a historical tour. Subsequently, it focuses on operation, taking a hydrogen cell as an example and then talks about the other types of batteries.
Videos in English
1º How does a fuel cell work?.
• - Direct link.
• - Author: Naked Science Scrapbook.
• - Duration: 4:01 min.
• - Description: Introduction to fuel cells. The explanations are made through drawings in a notebook accompanied by a voice-over. It begins by announcing them as the possible technology of the future and refers to their possible applications on different devices. It explains its operating principles using a hydrogen cell as an example and then explains the operation and applications of PEMFCs, AFCs and SOFCs. He repeatedly alludes to the advantages that these devices offer over traditional methods of obtaining electricity.
2º How a fuel cell works?.
• - Direct link.
• - Author: University of Waterloo Alternative Fuel Cell Team.
• - Duration: 1:51 minutes.
• - Description: informative explanation about the operation of the hydrogen fuel cell car. Its location inside the vehicle is shown, as well as that of the fuel. The operation is explained, what happens within an individual cell through an animation.
3ºBuilding a Fuel Cell Stack..
• - Direct link.
• - Author: Schatz Energy Research Center.
• - Duration: 11:05 minutes.
• - Description: this video shows the assembly process of a PEM type fuel cell stack. It begins by briefly explaining the operating mechanism of a fuel cell of this type. Finally, we are shown how to assemble it step by step, all accompanied by the relevant explanations.
4th OWI's Salt Water Fuel Cell Car..
• - Direct link.
• - Author: ABC News.
• - Duration: 1:45 minutes.
• - Description: The video shows a toy car whose fuel is salt water that can run continuously for 5 to 7 hours. This car gives both children and adults the opportunity to learn about forms of clean energy.
5th Toyota's Fuel Cell Vehicle: A Zero-Emission Car Coming 2015!.
• - Direct link.
• - Author: DNews.
• - : 3:27 minutes.
General
Literature
• - Gregor Hoogers, Hoogers Hoogers - Fuel Cell Technology Handbook - Publisher:CRC Press January 2003 - ISBN 0-8493-0877-1.
• - Venkatachalapathy, R., G. P. Davila, et al. (1999). "Catalytic decomposition of hydrogen peroxide in alkaline solutions." Electrochemistry Communications 1:614-617.
• - Wikimedia Commons hosts a multimedia gallery on Fuel Cell.
• - Fuel Cells (animations).
• - Fuel Cells.
• - Fuel Cell or Cell, Short video from the Discovery Channel.
[2] ↑ Life cycle assessment of PEM FC applications: electric mobility and μ-CHP. Dominic A. Notter,*a Katerina Kouravelou,b Theodoros Karachalios,b Maria K. Daletouc and Nara Tudela Haberlandad; Energy Environ. Sci., 2015,8, 1969-1985 DOI: 10.1039/C5EE01082A.
[3] ↑ Fuel Cell Hand Book. EG&G Technical Services, Inc. 2004. ISBN 9780442319267.
[4] ↑ Enciclopedia de los niños. Printer Latinoamérica, LTDA. 1990. ISBN ISBN 958-28-0193-X (Colección) / ISBN 958-28-0195-6 (Tomo 2) |isbn= incorrecto (ayuda).
[7] ↑ Pilas de combustible: una alternativa limpia de producción de energía Ricardo Escudero-Cid, Enrique Fatás, Juan Carlos Pérez-Flores y Pilar Ocón,2013.
[9] ↑ Grove, William Robert. "On Voltaic Series and the Combination of Gases by Platinum", Philosophical Magazine and Journal of Science vol. XIV (1839), pp. 127–130.
[10] ↑ a b Fuel Cell Technology Handbook. CRC Press. 2002. ISBN 9781420041552.
[11] ↑ Bacon, F.T., Research into the properties of the hydrogen-oxygen fuel cell, BEAMA Journal, 61, 6–12, 1954.
[18] ↑ CORPORATION, TOYOTA MOTOR. «Toyota Launches the New Mirai | Toyota | Global Newsroom». Toyota Motor Corporation Official Global Website (en inglés). Consultado el 23 de octubre de 2025.: https://global.toyota/en/newsroom/toyota/33558148.html
[21] ↑ A.J. Appleby, F.R. Foulkes, Fuel Cell Handbook, Van Nostrand Reinhold, New York, NY,1989.
[22] ↑ Performance of non-porous graphite and titanium-based anodes in microbial fuel cells Annemiek ter Heijne, Hubertus V.M. Hamelers, Michel Saakes, Cees J.N. Buisman. 2008.
[23] ↑ REVIEWS ON SOLID OXIDE FUEL CELL TECHNOLOGY,Navadol Laosiripojanaa, Wisitsree Wiyaratnb,Worapon Kiatkittipongc, Arnornchai Arpornwichanopd,Apinan Soottitantawatd, and Suttichai Assabumrungratd,2009.
[24] ↑ a b c d e f g h i Fuel Cell HandBook, Seventh Edition, EG&G Technical Services, Inc., 2004.
[27] ↑ Gottesfeld, S. and Pafford, J., A new approach to the problem of carbon monoxide poisoning in fuel cells operating at low temperatures, Journal of the Electrochemical Society, 135, 2651–2652, 1988.
[28] ↑ Pilas de combustible: una alternativa limpia de producción de energía Ricardo Escudero-Cid, Enrique Fatás, Juan Carlos Pérez-Flores y Pilar Ocón,2013.
[34] ↑ a b S.N. Simons, R.B. King and P.R. Prokopius, in Symposium Proceedings Fuel Cells Technology Status and Applications, Figure 1, p. 46, Edited by E.H. Camara, Institute of Gas Technology, Chicago, IL, 45, 1982.
[35] ↑ a b c d e F. Barbir, PEM fuel cell, ELSEVIER, 2005.
[36] ↑ Fundamentos de transferencia de calor, Frank P.Incropera, David P. DeWitt, Pearson Educación, 1999.
[37] ↑ Fuchs, M. and F. Barbir, Development of Advanced, Low-Cost PEM Fuel Cell Stack and System Design for Operation on Reformate Used in Vehicle Power Systems, Transportation Fuel Cell Power Systems, 2000 Annual Progress Report (U.S. Department of Energy, Office of Advanced Automotive Technologies, Washington, D.C., October 2000) pp. 79-84.
[40] ↑ "Fuel Cell Basics: Applications" Archivado el 15 de mayo de 2011 en Wayback Machine. Fuel Cells 2000. Accessed 2 August 2011.: http://www.fuelcells.org/basics/apps.html
[41] ↑ a b c "Types of Fuel Cells". Department of Energy EERE website, accessed 4 August 2011 http://energy.gov/eere/fuelcells/fuel-cells.: http://energy.gov/eere/fuelcells/fuel-cells
[43] ↑ "2008 Fuel Cell Technologies Market Report" Archivado el 4 de septiembre de 2012 en Wayback Machine.. Bill Vincent of the Breakthrough Technologies Institute, Jennifer Gangi, Sandra Curtin, and Elizabeth Delmont. Department of Energy Energy Efficiency and Renewable Energy. June 2010.: http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/48219.pdf
[44] ↑ U.S. Fuel Cell Council Industry Overview 2010, p. 12. U.S. Fuel Cell Council. 2010.
[57] ↑ H.I. Onovwiona and V.I. Ugursal. Residential cogeneration systems: review of the current technology. Renewable and Sustainable Energy Reviews, 10(5):389 – 431, 2006.
[58] ↑ AD. Hawkes, L. Exarchakos, D. Hart, MA. Leach, D. Haeseldonckx, L. Cosijns and W. D’haeseleer. EUSUSTEL work package 3: Fuell cells, 2006.
[61] ↑ Wipke, Keith, Sam Sprik, Jennifer Kurtz and Todd Ramsden. "Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project" Archivado el 16 de octubre de 2011 en Wayback Machine.. National Renewable Energy Laboratory, 11 September 2009, accessed on 2 August 2011.: http://www.nrel.gov/hydrogen/pdfs/46679.pdf
[63] ↑ Wipke, Keith, Sam Sprik, Jennifer Kurtz and Todd Ramsden. "National FCEV Learning Demonstration" Archivado el 19 de octubre de 2011 en Wayback Machine.. National Renewable Energy Laboratory, April 2011, accessed 2 August 2011.: http://www.nrel.gov/hydrogen/pdfs/51564.pdf
[65] ↑ Brinkman, Norma, Michael Wang, Trudy Weber and Thomas Darlington. "Well-To-Wheels Analysis of Advanced Fuel/Vehicle Systems – A North American Study of Energy Use, Greenhouse Gas Emissions, and Criteria Pollutant Emissions". General Motors Corporation, Argonne National Laboratory and Air Improvement Resource, Inc., May 2005, accessed 9 August 2011.: http://www.transportation.anl.gov/pdfs/TA/339.pdf
[72] ↑ Brian Warshay, Brian. "The Great Compression: the Future of the Hydrogen Economy", Lux Research, Inc. January 2013.
[73] ↑ Bossel, Ulf. "Does a Hydrogen Economy Make Sense? Proceedings of the IEEE Vol. 94, No. 10, October 2006.
[74] ↑ Meyers, Jeremy P. "Getting Back Into Gear: Fuel Cell Development After the Hype". The Electrochemical Society Interface, Winter 2008, pp. 36–39, accessed 7 August 2011.
[75] ↑ Eberle, Ulrich and Rittmar von Helmolt. "Sustainable transportation based on electric vehicle concepts: a brief overview". Energy & Environmental Science, Royal Society of Chemistry, 14 May 2010, accessed 2 August 2011.
[76] ↑ Zyga, Lisa. "Why a hydrogen economy doesn't make sense". physorg.com, 11 December 2006, accessed 2 August 2011, citing Bossel, Ulf. "Does a Hydrogen Economy Make Sense?" Proceedings of the IEEE. Vol. 94, No. 10, October 2006.
[77] ↑ Kubota, Yoko. "Toyota says slashes fuel cell costs by nearly $1 million for new hydrogen car". Reuters, Oct 10, 2013.
[78] ↑ Lienert, Anita. "Mercedes-Benz Fuel-Cell Car Ready for Market in 2014". Edmunds Inside Line, 21 June 2011.
[79] ↑ Korzeniewski, Jeremy (27 September 2012). "Hyundai ix35 lays claim to world's first production fuel cell vehicle title". autoblog.com. Retrieved 2012-10-07.
[80] ↑ "GM's Fuel Cell System Shrinks in Size, Weight, Cost". General Motors. 16 March 2010. Retrieved 5 March 2012.
[81] ↑ "Honda unveils FCX Clarity advanced fuel cell electric vehicle at motor show in US". Honda Worldwide. Retrieved 5 March 2012.
[82] ↑ "Environmental Activities: Nissan Green Program 2016". Nissan. Retrieved 5 March 2012.
[83] ↑ Chu, Steven. "Winning the Future with a Responsible Budget". U.S. Dept. of Energy, 11 February 2011.
[84] ↑ Matthew L. Wald (7 May 2009). "U.S. Drops Research into Fuel Cells for Cars". The New York Times. Retrieved 2009-05-09.
[85] ↑ Bullis, Kevin. "Q & A: Steven Chu", Technology Review, 14 May 2009.
[86] ↑ Steven Chu turns out to be a supporter of Hydrogen Technologies – on 2.10 min.
[87] ↑ Motavalli, Jim. "Cheap Natural Gas Prompts Energy Department to Soften Its Line on Fuel Cells", The New York Times, 29 May 2012.
[88] ↑ "Transportation Fleet Vehicles: Overview". UTC Power. Accessed 2 August 2011.
[89] ↑ "FY 2010 annual progress report: VIII.0 Technology Validation Sub-Program Overview".John Garbak. Department of Energy Hydrogen Program.
[90] ↑ a b "National Fuel Cell Bus Program Awards". Calstart. Accessed 12 August 2011.
[91] ↑ "Fuel cell buses". Transport for London. Archived from the original on 13 May 2007. Retrieved 2007-04-01.
[92] ↑ "Ônibus brasileiro movido a hidrogênio começa a rodar em São Paulo" (in Portuguese). Inovação Tecnológica. 8 April 2009. Retrieved 2009-05-03.
[147] ↑ a b c d e f "Fuel Cell Technologies Program: Glossary" Archivado el 23 de febrero de 2014 en Wayback Machine.. Department of Energy Energy Efficiency and Renewable Energy Fuel Cell Technologies Program. 7 July 2011. Accessed 3 August 2011.: http://www1.eere.energy.gov/hydrogenandfuelcells/glossary.html#c
One of the first practical applications of fuel cells was in space vehicles, based on the reaction of hydrogen and oxygen, resulting in water, which can be used by astronauts for drinking, or to cool the ship's systems.[4].
The fuel cell market is growing. Pike Research estimated that in 2020 stationary fuel cells will be commercialized, all of them reaching a combined power of 50 Gw.[5].
The Japanese automobile manufacturer Honda, the only firm that has obtained approval in Japan and the United States to market its vehicle powered by this system, the FCX Clarity, has also developed the (HES) Home Energy Station") (in:")), an autonomous and domestic system that allows obtaining hydrogen from natural gas to refuel fuel cell vehicles and takes advantage of the process to generate electricity and hot water for the home.
History
Contenido
Aunque parezca algo muy reciente, la historia de las pilas de combustible comenzó hace casi dos siglos, en 1838,[6] con los primeros estudios del científico Christian Friedrich Schönbein en Suiza y, paralelamente, con los del físico y jurista galés Sir William Robert Grove sobre baterías gaseosas, cuyos resultados publicaría en 1843. Hoy en día, se continúa con el empleo de estas células en diversas aplicaciones, tanto portátiles (ejemplo: teléfonos móviles) como estacionarias (ejemplo: generación de energía para edificios), así como en diversos medios de transporte (desde submarinos hasta vehículos particulares). Sin embargo, su desarrollo ha atravesado periodos de olvido, debido a las numerosas dificultades técnicas que presentan en comparación con otros métodos de obtención de electricidad. El interés por las células de combustible, y por tanto su desarrollo, se ha dado en periodos de escasez de recursos energéticos - por ejemplo, la crisis del petróleo de 1973 que precipita el desarrollo de tecnologías alternativas de energía, incluyendo las células de combustible[7] -. Esto se debe a que estas células, comparadas con otros dispositivos, tienen mayor eficiencia energética y por tanto necesitan menos combustible para producir la misma energía.
1843
The figure shows the device presented to the scientific community by William Robert Grove in his publication "On the Gas Voltaic Battery".[8][9] For its preparation, he used two platinum electrodes immersed in sulfuric acid, which he fed with oxygen and hydrogen, respectively. From the dissociation of H2SO4, the reduction took place at the electrode fed with O2 (cathode), which reacted with the H+ ions forming water. Electrons were involved in this reaction, which were generated at the anode during the oxidation of H2, which reacted with the SO42- ion to form sulfuric acid[2]. Grove electrically connected fifty of these cells, generating enough potential to produce the water electrolysis reaction.
1882
The British physicist Lord Rayleigh improved this original configuration. Rayleigh became interested in Grove's work and in 1882 presented a new, more efficient version, due to the increase in the contact surface between the platinum, the reactive gases and the electrolyte.[10].
Ludwig Mond and Charles Langer first used the term "fuel cell" to refer to this type of device. In 1889, these two scientists made a breakthrough, solving the problem associated with the immersion of the electrodes in the liquid electrolyte and therefore, the difficulty of access of the reactive gases to the active points. Its prototype allowed the electrolyte to be retained in a solid non-conductive matrix, whose surface was covered by a thin layer of Platinum or Gold.[10].
1950s and 1960s
In the middle of the century, the technological development of these devices experienced great progress. In 1954, English scientist Francis Thomas Bacon built a 5 kW power plant using an alkaline fuel cell. The cell consisted of a nickel anode, a lithium nickel oxide cathode, and an 85% concentrated potassium hydroxide electrolyte. It was fueled with hydrogen and oxygen.[11] This battery was capable of powering a welding machine. In the 1960s, Bacon's patents (licensed by Pratt and Whitney in the United States - at least the original idea) were used in the United States space program to provide astronauts with electricity and drinking water, from the hydrogen and oxygen available in the spacecraft's tanks.
In 1959, a team led by Harry Ihrig built a 15 kW fuel cell-based tractor for Allis-Chalmers. It was exhibited in the US at state fairs. This system used potassium hydroxide as the electrolyte and compressed hydrogen and oxygen as reactants.[12].
In parallel with Pratt & Whitney Aircraft, General Electric developed the first proton exchange membrane stack (PEMFCs) for NASA's Gemini space missions. The first mission to use PEFCs was Gemini V. However, the Apollo Program missions and the subsequent Apollo-Soyuz, Skylab and shuttle missions used fuel cells based on the Bacon design, developed by Pratt & Whitney Aircraft.[13].
1970s and 1980s
Between 1970 and 1980, as a consequence of the oil crisis and the search for alternative energy technologies, research was carried out on the development of the necessary materials, the identification of optimal fuel sources and the drastic reduction in the cost of the technology associated with fuel cells.
During the 1980s, the use of fuel cells began to be tested in utilities and was also attempted in automobile manufacturing. In the 1990s, large stationary (fixed) fuel cells were developed for commercial and industrial premises.
1993 and 2007
In 1993, the Canadian company Ballard developed the first commercial fuel cell vehicle, using PEM technology.
In 2007, fuel cells are marketed for stationary and auxiliary applications. In 2008, Honda begins sales of a fuel cell-based electric vehicle, FCX Clarity. That same year, the Nobel Prize in Chemistry was awarded to Gerhard Ertl, whose studies revealed how fuel cells work.
Panasonic was the first company in the world to sell the fuel cell for home use. From its launch (May 2009) to September 2013, it sold 31,000 units in Japan.[15].
2013
In 2013, a fuel cell is presented that could represent the transition to affordable batteries. The British company "ACAL Energy" has developed a fuel cell that has achieved a run time of 10,000 hours in fuel cell endurance tests[16] using its FlowCath technology. Unlike a conventional hydrogen fuel cell design, ACAL's FlowCath technology does not rely on platinum as a catalyst, offering a potentially lower cost alternative. It has replaced platinum with a patented liquid catalyst, which acts as a coolant and catalyst for the cells and radically improves the durability of the fuel cell, while reducing the cost of the system.[17].
2014 - Present
The last decade has seen commercial consolidation of the technology and a critical focus on sustainability. Fuel cell vehicles (FCEVs), such as the Toyota Mirai (2014) and Hyundai Nexo (2018), have established a niche market, albeit with modest volumes compared to battery electric vehicles.[18].
The greatest conceptual advance has been the turn towards green hydrogen, produced with renewable energy, recognized as essential for the technology to be truly clean. This has driven national strategies in the EU, Japan and South Korea.[19].
The most promising applications are now in heavy transport. Trucks, city buses and the first fuel cell passenger trains, such as Alstom's Coradia iLint in Germany, are being deployed, replacing diesel fleets on non-electrified lines.[20].
Technology
El funcionamiento de la pila de combustible es similar al de una batería. Se obtiene electricidad a partir de sustancias que reaccionan químicamente entre sí. Sin embargo, mientras que las baterías tienen una capacidad limitada de almacenamiento de energía, la pila de combustible está diseñada para permitir un abastecimiento continuo de los reactivos. Además, los electrodos de la pila de combustible actúan también como catalizadores de las reacciones químicas de oxidación/reducción.
Existen tipos muy distintos de pilas de combustibles. Para explicar su funcionamiento básico, se toma como ejemplo una de las más comunes, la denominada PEM (de membrana de intercambio protónico, en inglés Proton Exchange Membrane). El esquema básico de la celda unitaria de una pila PEM se muestra en la figura de la derecha. Consta de dos electrodos: el ánodo (donde se oxida el combustible) y el cátodo (donde el oxidante o comburente se reduce). El electrolito actúa simultáneamente como aislante eléctrico, conductor protónico y separador de las reacciones que tienen lugar en el cátodo respecto a las que tienen lugar en el ánodo. Debido a lo anterior, los electrones viajan desde el ánodo hasta el cátodo a través de un circuito externo, generando una corriente eléctrica, mientras que los protones lo hacen a través del electrolito. En el cátodo, los electrones, protones y el comburente se reducen, dando lugar a los productos. La reacción es exotérmica y, aunque es espontánea, suele ser muy lenta como para ser operativa sin la presencia de catalizadores. De hecho, lo más común es que los propios electrodos se utilicen como catalizadores. En este tipo de pilas se suele utilizar hidrógeno como agente reductor y oxígeno como oxidante.
Es importante mencionar que, para que los protones puedan atravesar la membrana, esta debe estar convenientemente humidificada, porque la conductividad protónica de las membranas poliméricas utilizadas en este tipo de pilas depende de la humedad de la membrana. Por lo tanto, es habitual humidificar los gases previamente al ingreso a la pila.
Además de hidrógeno puro, también se tiene el hidrógeno contenido en otras moléculas de combustibles incluyendo el diésel, metanol (véase DMFC")) y los hidruros químicos. El residuo producido por este tipo de combustibles además de agua es dióxido de carbono, entre otros.
Las pilas de combustible se pueden clasificar en función del electrolito y del combustible elegido, lo que a su vez determina el tipo de reacciones que se llevarán a cabo en los electrodos y los tipos de iones que la corriente transportará a través del electrolito.
Hoy en día, la mayoría de las células de combustible en desarrollo utilizan hidrógeno o gases sintéticos ricos en hidrógeno. El hidrógeno tiene una alta reactividad y puede obtenerse de formas muy diversas tanto a partir de combustibles fósiles o renovables, como a partir de un proceso electrolítico. Por razones prácticas, el oxidante más común es el oxígeno gaseoso, debido a su alta disponibilidad. Una ventaja de utilizar la combinación de hidrógeno con oxígeno, es que el único producto de la reacción es agua. Por esto, esta combinación es muy utilizada en aplicaciones espaciales. Además, oxígeno y el hidrógeno pueden almacenarse criogénicamente de forma compacta.
La diferencia de potencial generada por una sola unidad o monocelda es inferior a un voltio, por lo que hay que conectar en serie varias mono-pilas para obtener las tensiones adecuadas para las aplicaciones más comunes. Por lo tanto, en la práctica se utilizan sistemas de pilas de combustible.
Strain
The cell voltage depends on the charging current. In open circuit, it is 1.2 volts. To create sufficient voltage, the cells are grouped by combining them in series and parallel, in what in English is called a "Fuel Cell Stack". Generally, more than 45 are used, although they vary depending on the design.
Materials
The materials used in fuel cells vary depending on the type. See Types of fuel cells.
Electrode/bipolar plates are generally made of metal, nickel or carbon nanotubes, and are covered by a catalyst (such as platinum or palladium) to achieve higher efficiency.
The electrolyte can be ceramic or a hybrid polymer electrolyte membrane. This consists of two different polymers. They are arranged in such a way that both constitute a structure where one of the polymers (which is a siloxane polymer) acts as a perforated base so that the other (a polymeric electrolyte) can distribute the perforations in the form of channels.
Design considerations in fuel cells
• - Costs. In 2002, typical cells had a cost due to the catalyst of €850 (approx. 1000 USD) per kilowatt of useful electrical energy; however, it is expected that before 2007, it will be reduced to about €25 (approx. $30) per kilowatt [3]. Using a catalyst enhanced with carbon silk, Ballard has achieved a 30% reduction (1 mg/cm² to 0.7 mg/cm²) in the amount of platinum, without reducing its performance (information from 2005)[4].
• - Water management in PEMFCs. In this type of fuel cell, the membrane must be hydrated, requiring water to evaporate at exactly the same rate as it is produced. If the water evaporates too quickly, the membrane dries out, the resistance across it increases, and 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 evaporates too slowly, the electrodes will flood, preventing the reactants from reaching the catalyst and the reaction will stop. One of the most important objectives in fuel cell research is proper water management.
• - Temperature management. The same temperature must be maintained throughout the cell to avoid destroying the cell due to thermal fatigue.
• - Flow control. As in a combustion engine, a constant ratio between reactant and oxygen must be maintained for the cell to function efficiently.
• - Durability, life, and special requirements for certain cell types. Stationary uses typically require more than 40,000 hours of reliable operation at -35°C to 40°C, while automotive fuel cells require at least 5,000 hours (the equivalent of about 200,000 kilometers) under extreme temperatures. (See: Hydrogen vehicle). Additionally, automotive applications must allow cold starting down to -30°C and have high power per unit volume (typically 2.5 kW per liter).
• - Limited tolerance to CO (carbon monoxide).
Fuel cell systems
Unit cell
The unit cell or mono-cell is the basic element of a fuel cell-based system. The elements that make it up are described below:
• - Electrolyte. It is at the same time ionic conductor, electrical insulator and separator of the cathode and anode. Depending on the state of aggregation of the electrolyte, we can find two types of fuel. Thus, according to Appleby and Foulkes,[21] we have:
Liquid electrolyte fuel cells. In this type, the electrodes are porous and the electrolyte is in contact with them, soaking small areas. The gaseous reactants diffuse through a thin layer of electrolyte and react electrochemically on the electrode surfaces. The amount of electrolyte that the electrode can contain is limited. Therefore, an excess of liquid could prevent the transport of gaseous species and also the reactions necessary to obtain energy.
Solid electrolyte fuel cells. This type contains a high number of catalysts at the interface, which must be electrically and ionically connected to the electrodes and the electrolyte respectively, and which are also efficiently exposed to the gaseous reagents.
• - Electrodes. Electrochemical reactions take place on the surface of the electrodes. Fuel is oxidized at the anode and oxygen is reduced at the cathode. The electrodes are usually porous, to allow gaseous diffusion (although there are some non-porous ones[22]). In this way, good contact can be established between the three phases that participate in the reaction (the solid phase of the electrode, the gaseous phase of the fuel, and the liquid or solid phase of the electrolyte). The main functions of the electrodes are:
Conduct or dislodge ions from the ternary interface.
Ensure that the gaseous reactants are evenly distributed in the electrolyte.
Ensure that the reaction products are efficiently carried into the gas phase.
Stacks
Since the potential difference generated by a single fuel cell is small (approximately 0.7 volts), in practice several are combined in series to achieve the appropriate output voltage for the desired application. Logically, the interconnections between the unit cells are made using materials with high electrical conductivity. Among the numerous types of possible stacks, the most common are those with a flat structure, although there are also tubular ones.
In flat structure stacks, elements known as "bipolar plates" are normally included (see Fuel Cells (animations)). They consist of two separator plates located at the ends of the system. through which connections are made. One acts as an anode and another as a cathode. Additionally, these plates separate the fuel and oxidant from adjacent cells, in turn providing an excellent means for supplying these reactants. In many designs, the plates include channels (see figure to the right) that allow uniform distribution of gas flow over the cells. This design is quite simple electrically: the path that the electric current travels is relatively short and, therefore, offers little resistance to the passage of electrons, and consequently little voltage drop.
Another type of stacking, especially indicated for fuel cells that work at high temperatures (such as solid oxide-SOFC), consists of a tubular configuration (figure on the left). These types of batteries usually use a solid ceramic material, such as zirconium oxide stabilized with yttrium oxide, as the electrolyte, instead of a liquid or an exchange membrane.
Systems based on fuel cells
While the fuel cell itself is the key component, a fuel cell-based system must include other subsystems and components, known as balance of plant (BOP). A fuel cell-based system is then formed by a stack of fuel cells and a BOP, properly combined.
There is a wide variety of configurations for this type of system. Indeed, the precise composition and arrangement of the BOP elements depends largely on the type of fuel cell, the operating temperature, the fuel chosen and the application for which it is used. Additionally, the specific operating conditions and requirements of the individual cell and stack design determine the characteristics of the BOP.
However, even taking into account the diversity and flexibility of these systems, it is advisable to show at least one example of the components (or stages) that make up a system based on fuel cells. The figure shows a schematic of a generic system based on fuel cells. As can be seen, in the first stage, the fuel (hydrogen, natural gas, methane, etc.) is introduced into the reformer in which, through a chemical transformation, a gas rich in hydrogen known as "reformed" is produced and as a by-product, carbon monoxide with a concentration level of less than 50 ppm.
The next stage takes place in the gas purification system, where any impurities that the reformed product may have are eliminated. Once the hydrogen is purified, it is ready to be introduced into the fuel cell. In this stage, electrical energy is generated through the electrochemical reaction with oxygen. The heat generated in the reaction can be used to preheat the fuel. In the case of fuel cells that operate at high temperatures (between 600-1000 °C), the heat generated could be invested in cogeneration, that is, it can be used to drive gas turbines and generate more electricity, for desulfurization units, generation of chemical products, etc.[23].
Types of fuel cells
Actualmente existe una gran variedad de pilas de combustible en diferentes etapas de desarrollo. Por ello, se pueden clasificar atendiendo a numerosas características. Las más comunes son las siguientes:[24].
Según el tipo de combinación de combustible y oxidante. Los combustibles típicos son el hidrógeno molecular y el metanol, y normalmente oxígeno o aire como oxidante. Pero como se ha visto en la figura 2.4, se pueden alimentar con una amplia variedad de combustibles, como hidrógeno, metanol, biomasa, gasolina, carbón, etc.
Según el tipo de electrolito usado. Por ejemplo: ácido fosfórico, membrana de polímero sólido, solución alcalina, etc.
Según la temperatura de operación. Por un lado, tenemos pilas de combustible de baja o media temperatura (con temperaturas inferiores a 200 °C), como las PEM, las AFC y las PAFC. Por otro, las de alta temperatura, que sobrepasan los 600 °C, como las MCFC y las SOFC. Según la fuente que se consulte, los rangos son ligeramente distintos, por lo que esta clasificación no es estricta.
Según su eficiencia. En este caso, el rango es distinto dependiendo del tipo de pila y del tipo de aplicación en la que se utilice. Por ejemplo, para una PEM tiene una eficiencia en torno a un 40%[24] en aplicaciones estacionarias y en torno a un 60% en aplicaciones para el transporte.
Según el tipo de uso. Aplicaciones portátiles, estacionarias, de transporte, militares, espaciales, etc.
Según su potencia. Pilas de baja potencia (alrededor de 5 kW en el caso de las DMFC, por ejemplo) y de alta potencia (100 kW a 2 MW en las SOFC, por ejemplo).[25].
Según el catalizador utilizado. Típicamente, platino, metales no preciosos o el propio material de los electrodos. También pueden ser de paladio.[26].
La forma más usual de clasificación es por el tipo de electrolito que utilizan. Se pueden entonces establecer,[24] cinco tipos principales de pilas, que se describen a continuación.
Proton Exchange Membrane (PEM) Fuel Cell
• - Electrolyte: solid polymer membrane.
• - Catalyst: platinum.
• - Operating temperature: around 80-95 °C.
• - Electrical efficiency: 40-60%.
PEMs operate at relatively low temperatures, have high power density, and can rapidly vary their power output to adapt to energy demand. There are PEMs with powers that vary between a few watts and several kilowatts, so they can be used in a multitude of systems. Thus, until 2013 the maximum power achieved with a stationary power plant (fixed energy installation) type PEM is 1 MW, and was installed by the Japanese company Honda[6].
PEM type fuel cell systems are suitable for applications requiring rapid operating response. Thus, they are used in a wide variety of systems that focus on the telecommunications market (both industrial and home) and in vehicles for transporting materials, such as forklifts. They are also used in buses and it is expected that between 2014-2016 passenger vehicles (passenger cars like the one shown in the figure) from PEM can be marketed. PEMs can use hydrogen, methanol or reformed fuels as fuel.
In PEMs, the electrolyte is a solid polymer membrane containing perfluorinated sulfonic acids, and must be kept fully hydrated during operation to promote proton conduction. This requirement limits the operating temperature to below 100 °C and is essential to obtain good efficiency. Since water is the only liquid used, corrosion problems are minimal.[25].
The main current challenges in the development of this type of batteries are: reducing cost and increasing efficiency (which translates into reducing the thickness of the platinum catalytic layer and optimizing the dispersion of the catalyst); improve the performance of the polymeric membrane (increase ionic conductivity and water retention capacity); and find an alternative material to graphite for the bipolar plate that is high in electrical and thermal conductivity, resistant to corrosion, lighter and cheaper.[25].
High-temperature proton exchange membrane (High-temperature PEM or HT-PEM).
HT-PEMs are, in essence, PEMs that can operate at high temperatures, between 120 °C and 200 °C. They are usually used in vehicles and, less commonly, to supply energy to buildings. HT-PEMs often integrate a reformer (that is, a device capable of reforming fossil fuels or alcohols into synthetic gas consisting mainly of hydrogen and carbon monoxide), which allows them to be fed with a greater variety of fuels.
Methanol Fuel Cell (DMFC)
• - Electrolyte: solid polymer membrane.
• - Catalyst: Platinum.
• - Operating temperature: around 50-120 °C.
• - Electrical efficiency: above 40%.
Like PEMs, DMFCs use a polymer membrane as electrolyte. However, in DMFC systems it is not necessary for the fuel to pass through a reformer, since the catalyst anode itself extracts hydrogen from liquid methanol. Since the minimum operating temperature of this type of battery is low, DMFC can be used in small applications, such as mobile phones (see figure on the right), laptop computers and battery chargers for other electronic products [7] Archived on July 14 2014 on the Wayback Machine., and also in medium-sized applications to power the electronics of boats or cabins.
In this type of batteries, the challenge is to find a membrane that allows working at temperatures above 130 °C and that does not present "crossover" problems (passage of the anodic reactant to the cathode compartment through the membrane) and to find a more active anodic catalyst for the direct oxidation of methanol.[25].
Alkaline Fuel Cells (AFC)
• - Electrolyte: a solution of potassium hydroxide in water.
• - Catalyst: a wide variety of non-precious metals can be used.
• - Operating temperature: between 105-245⁰C.
• - Electrical efficiency: 60-70%.
The fuel and oxidizer used in AFCs must be pure hydrogen and oxygen. Indeed, CO2 (or CO) reacts with KOH and potassium carbonate is formed, which greatly reduces the efficiency of the fuel cell.[25] Even with small concentrations (10 to 100 ppm) "poisoning" of the cell by carbon monoxide or dioxide occurs.[27] For this reason, they are mainly used in the aerospace sector and underwater environments, figure 2.15.
The electrolyte concentration is around 35-50% for operating temperatures below 120 °C, and can operate at 250 °C when the concentration is 85%.[25].
These batteries are the ones that offer the highest performance. It is one of the reasons why they are used in space exploration, since the fuel must be put into orbit and the mass to be lifted has to be optimal. NASA has used hydrogen-powered AFCs on space missions since 1960 to provide electricity and drinking water.[28].
Phosphoric Acid Fuel Cell (PAFC)
• - Electrolyte: Liquid phosphoric acid.
• - Catalyst: Platinum based on carbon.
• - Operating temperature: between 180-205⁰C.
• - Electrical efficiency: 36-42%.
PAFCs can use hydrocarbons or biogas as fuel. The reactions at the cathode and anode are similar to those that occur in PEMs, but the operating temperature is higher and they also tolerate impurities that the fuel may have better.
PAFCs are frequently used in cogeneration. Today, the commercialization of PAFCs is widespread. They are frequently used to provide electricity to buildings with high energy demand, both public and private.
In 1991, UTC put the first power generation plant based on this fuel cell technology on the market. The PureCell power system, see figure, supplies 200 kW of power and about 850 J of energy every hour. The accumulated operating time for all units sold exceeds 6 million hours.[25].
Molten Carbonate Fuel Cell (MCFC)
• - Electrolyte: alkaline carbonates on a ceramic matrix.
• - Catalyst: from the electrodes (not platinum).
• - Operating temperature: around 650 °C.
• - Electrical efficiency: 50-60%.
In this type of cells, the high operating temperature allows the internal reforming of the fuel, that is, the conversion of fuel to hydrogen is done within the cell itself. Since MCFCs are not prone to contamination with CO or CO2, they can even use carbon oxides as fuel, something that makes them especially suitable for feeding them with gases from coal. MCFCs are used in stationary applications and in cogeneration, to provide energy to public or private buildings.
This technology has been in development for a long time. The following link shows a photo of a 100 W power system based on MCFC technology and manufactured by Texas Instruments in 1966. The greatest exponents in the development of this technology have been the German MTU, and its American partner, Fuel Cell Energy.[25].
Solid Oxide Fuel Cell (SOFC)
• - Electrolyte: ceramic solid or non-porous metal oxide.
• - Catalyst: electrode material (not platinum).
• - Operating temperature: 800-1000 °C.
• - Electrical efficiency: 50-60%.
These types of high-temperature cells are designed to reform light hydrocarbons (such as natural gas) internally. Therefore, if heavier hydrocarbons (such as gasoline) were to be used, an external reformer would be required.
Its shape can be flat or tubular. These types of batteries are used in a long list of stationary applications throughout the world.[29].
Given that these types of batteries currently operate between 800-1000 °C, the challenge is to go down to 600-800 °C (IT-SOFC, "Intermediate Temperature Solid Oxide Fuel Cell"). Research focuses on reducing the thickness of the electrolyte layer and on the search for new materials, based on lanthanide oxides or with a perovskite structure, that present high ionic conductivity at low temperature.[25].
Comparison between the different types
As a summary, the following table compares the main types of fuel cell in Marketing/research status.
Other types of fuel cells
The following table presents other types of fuel cells that are based on the main types, but that have their own characteristics that make them interesting for both general and specific applications.
Behavior
The Gibbs function and the Nernst potential
In a fuel cell, an electrochemical reaction occurs at constant temperature and pressure that will never reach equilibrium. The work that can be obtained under these conditions is called non-expansion work[30] and its maximum value coincides with the Gibbs free energy variation. In the case of an electrochemical reaction, this work is the electrical energy necessary to release the electrons, W, and is given by the change in the Gibbs function, ΔG, of the chemical reaction (it is also called reaction free energy):[30].
This expression is particularly useful for evaluating the electrical work that occurs in fuel cells and electrochemical cells. The electrical work is obtained by taking into account the number n of electrons released by each molecule produced in the chemical reaction, and the potential difference E that they acquire when released. This work is equal to –neE, e being the charge of the electron. If we want to express the reaction per mole instead of per molecule, we will have to multiply n by Avogadro's number, which will give us nN electrons for each mole produced. Therefore, the work associated with the generation of nN electrons, with a potential difference E, is:[24].
The product eN, which is the electric charge of one mole of electrons, is called Faraday's constant and is designated by the letter F. Therefore:.
being .[31].
The potential E is known as the Nernst potential[24] and gives the electrical voltage that can be obtained when an electrochemical reaction occurs reversibly. This potential is also known as electromotive force and is the one obtained under open circuit conditions, that is, in the absence of electric current.
It is usual to find the reaction free energy, or the data necessary to calculate it, (such as enthalpies and entropies) tabulated for the standard state "Standard conditions (chemistry)") of T = 298.15 K and P = 1 atm.[32] Said reaction energy in the standard state is denoted as ΔG. For a reaction that does not occur under these standard conditions it can be written [32].
where Q is the reaction quotient.
Dividing the previous equation by nF we obtain the so-called Nernst Equation:.
where E is known as the standard cell potential, which is nothing more than the standard Gibbs reaction energy expressed in Volts.
As in fuel cells it is normal to have the reactants and products in a gaseous state, then Q is obtained from the partial pressures:[24][30].
where ν and ν are the stoichiometric coefficients of the chemical reaction. So Nernst's potential in this case will be:
The Nernst potential is the equivalent of the “electromotive force” or “cell potential” of a battery, which is the potential difference observed in an open-circuit battery.
Performance
The ideal performance or efficiency of the chemical to electrical conversion is defined as the quotient between the electrical energy obtained in the case in which the current is infinitely small, W or as we saw in the first section of this section, ΔG, and the chemical energy put into play ∆H, we can write it as:.
As an example, the calculation of the ideal performance under standard conditions (T=298.15 K and P = 1 atm), η, can be made for a cell based on the reaction of hydrogen with oxygen:.
where the water produced is liquid. Under these conditions:[24].
therefore,.
For other electrochemical reactions the procedure would be analogous.
The performance of fuel cells, unlike combustion engines (internal and external), is not limited by the Carnot cycle since they do not follow a thermodynamic cycle. Therefore, its performance is very high in comparison, converting chemical energy into electrical energy directly.
The potential difference across the cell's electrodes decreases when current exists. For convenience, the performance of a fuel cell is often expressed in terms of the ratio between the ideal voltage and the actual voltage (at which the fuel cell operates), the latter being lower than the former due to ohmic losses and those associated with polarization mechanisms within the cell. The expression of the efficiency of the fuel cell is as follows:.
where V is the voltage measured between the electrodes in real operating conditions, and I is the current intensity that circulates through the external circuit. This efficiency is also known as voltage efficiency.[33] In this expression it is considered that all the fuel is being used, since this is the case in most combustion engines. However, in fuel cells the complete conversion of fuel is not usually carried out and it is necessary, to calculate the efficiency in real voltage, to multiply the previous equation by a factor that indicates how much fuel is being used.
Therefore, although the ideal performance seems very high, it is reduced by actual operating conditions.
A fuel cell typically converts the chemical energy of fuel into electricity with an efficiency of approximately 50%. The performance however depends largely on the current flowing through the fuel cell: the higher the current, the lower the performance.
Losses due to production, transportation and storage must also be considered. Fuel cell vehicles running on compressed hydrogen have an efficiency of 22% if the hydrogen is stored as a high-pressure gas, and 17% if it is stored as liquid hydrogen (these figures should justify your calculation methodology).
Fuel cells cannot store energy like a battery, but in some uses, such as stand-alone power plants based on "discontinuous" sources (solar, wind energy), they are combined with electrolyzers and storage systems to form an assembly to store this energy. The efficiency of the reversible process (from electricity to hydrogen and back to electricity) of such plants is between 30 and 40%.
Actual behavior
As indicated in previous sections, the Nernst potential gives the “electromotive force” of the fuel cell, that is, the potential difference between its electrodes in the absence of electric current. Once the circuit is closed and current begins to flow, potential losses appear related to charge conduction within the electrolyte and polarization phenomena. As a consequence, the potential difference measured between the electrodes is less than the ideal (Nernst potential) calculated in the previous section.
To clearly visualize the difference between both potentials, the potential is usually represented against the current density, giving rise to the so-called operating curve, also called polarization curve. This curve, as shown in the figure on the right, presents three main regions of operation.
As shown in parentheses, each of the regions shown in the previous graph has an associated source of efficiency loss:[24].
• - Activation losses: due to the low rate of reactions in the activation polarization region.
• - Ohmic (resistive) losses: related to the flow of electrons through the electrode material, as well as the resistance to the flow of ions through the electrolyte in the ohmic polarization region.
• - Concentration losses: changes in gas concentration or mass transport in the polarization region due to concentration.
Below we will see in more detail the types of losses mentioned.
These types of losses are due to the slowness of the reactions in the electrodes. For electrochemical reactions to begin, as in common chemical reactions, the reactants must exceed the activation energy. In reality, not a single reaction occurs in the electrodes but several, each with its own speed and activation energy. Thus, activation losses are the result of the losses due to each of these successive reactions.
Activation losses are expressed mathematically by the Tafel equation"):[34].
R≡ideal gas constant measured in J/molK.
T≡operating temperature in K.
α≡electron transport coefficient (dimensionalless).
n≡number of electrons per molecule (dimensionalless).
F≡Faraday constant in C/mol.
i≡current generated in A.
i≡exchange current (depends on the type of material), measured in A.
This equation is valid for values of ΔE≥(50-100)mV.[34].
According to Barbir[35] the factors that reduce activation losses are:
• - Increase in operating temperature.
• - Effective catalysts.
• - Use of pure oxygen as an oxidizing agent instead of air.
Variables that affect operation
The output potential of fuel cells is affected by the operating conditions (temperature, pressure, gas composition, use of reagents, current density), by the design of the cell and by other factors (impurities, durability of the device) that cause it to move away from the ideal value previously calculated. For more information about this type of losses, consult the following references.[24][35][37][38].
Fuel cell applications
Energy
Fuel cells are very useful as power sources in remote locations, such as spacecraft, remote weather stations, large parks, rural locations, and in certain military uses. A fuel cell system that runs on hydrogen can be compact, lightweight, and have no major moving parts. Because fuel cells have no moving parts and do not involve combustion, under ideal conditions they can reach up to 99.9999% reliability.[39] This is equivalent to less than one minute of downtime over a six-year period.[39].
Cogeneration applications (combined use of heat and electricity) for homes, office buildings and factories. This type of system generates electrical energy constantly (selling excess energy to the grid when it is not consumed), and at the same time produces air and hot water thanks to the heat it gives off. Phosphoric-Acid Fuel Cells (PAFC) comprise the largest segment of cogeneration applications worldwide and can provide combined efficiencies close to 80% (45-50% electrical + the rest as thermal). The largest manufacturer of PAFC fuel cells is UTC Power", a division of United Technologies Corporation. Molten Carbonate Fuel Cells (MCFCs) are also used for identical purposes, and prototypes of Solid-Oxide Fuel Cells (SOFCs) exist.
Electrolyzer systems do not store fuel themselves, so they require external storage units, which is why they are usually used in rural areas.[40] In this case, the batteries have to be large in size to meet the storage demand, but this still represents savings compared to conventional electrical devices.
There are many different types of stationary fuel cells so efficiencies vary, but most are between 40% and 60% energy efficient.[41] However, when waste heat from the fuel cell is used to heat a building in a cogeneration system this efficiency can increase to 85%,[41] i.e. almost three times more efficient than traditional coal plants.[42] Therefore, in large-scale production, fuel cells could save 20-40% in energy costs when used in cogeneration systems.[43] Fuel cells are much cleaner than traditional power plants; A fuel cell-based power plant using natural gas as a hydrogen source could generate less than one ounce (approximately 28.35 grams) of pollutants (other than CO2), for each kW/h produced, while conventional combustion systems would generate 25 ounces (708 grams).[44].
There is an experimental program on Stuart Island in Washington state,[45] where the Stuart Island Energy Initiative company has built a complete system in which solar panels generate the current to operate several electrolyzers that produce hydrogen. Said hydrogen is stored in a 1900 liter tank, at a pressure of 10 to 80 bar. This fuel is ultimately used to power a ReliOn brand 48V hydrogen fuel cell that provides enough electrical power for residential purposes on the island (see link external to SIEI.ORG). Another system of this type was installed in 2011 Hempstead, NY.[46].
Fuel cells can be used with low-quality gas from landfills or wastewater treatment plants to generate energy and reduce methane emissions. The largest fuel cell-based power plant is a 2.8 MW plant located in California.[47].
Protium, a rock band formed at Ponaganset High School in Glocester, was the first musical group in the world to use hydrogen fuel cells to provide energy. The band used a 1kW Ballard Power systems Airgen Fuelcell. The ensemble has played at numerous fuel cell related events including the CEP in Connecticut, and the 2003 Fuel Cell Seminar in Miami Beach.
Plug Power Inc. is another major company in the design, development and manufacturing of PEM fuel cells for stationary applications, including products aimed at telecommunications, basic power, and cogeneration applications.
Cogeneration
Combined fuel cell heat and power (CHP) systems, including micro combined heat and power (MicroCHP) systems, are used to provide heat and power to homes, office buildings and factories. These systems constantly generate electrical energy (selling excess to the grid when not consumed) and, at the same time, produce hot air and water with waste heat. As a result CHP systems have the potential to save primary energy as they can make use of waste heat, which is normally rejected by thermal energy conversion systems.[48] The typical power range of a domestic fuel cell is 1–3 kWel / 4–8 kWth.[49][50] CHP systems connected to absorption chillers use waste heat for cooling.[51].
The waste heat from the fuel cells can be diverted in summer directly to the ground for additional cooling while in winter the waste heat can be pumped directly into the building. The University of Minnesota owns the patent rights for this type of systems.[52][53].
Cogeneration systems can reach 85% efficiency (40-60% electrical and the rest thermal).[41] Phosphoric acid fuel cells (PAFC) are the most widely used in CHP products in the world and can achieve combined efficiencies close to 90%.[54][55] Molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC) are also used for combined heat and power production systems and They have an electrical efficiency close to 60%.[56] The disadvantages of these cogeneration systems include high costs and short duration.[57][58] In addition, their need to have a tank to store hot water to soften heat production represents a serious problem for the domestic market since space in homes represents a great cost.[59].
Fuel cell vehicles
Although there are currently no fuel cell-equipped vehicles available for large-scale sale, more than 20 fuel cell vehicle (FECV) prototypes and demonstration cars have been launched since 2009. Demonstration models include the Honda FCX Clarity, Toyota FCHV, Fiat Phyllis and Mercedes-Benz F-Cell.[60] Since 2011, FECV demonstration cars have traveled more than 4,800,000 km, with more than 27,000 recharges.[61] A range of 400 km between recharges has been achieved.[62] They can also be recharged in less than 5 minutes.[63] The Fuel Cell Technology Program of the US Department of Energy ensures that, as of 2011, fuel cells are achieving an efficiency between 53% and 59% at a quarter of its power and between 42% and 53% at full power[64] with a durability of 120,000 km with a degradation of less than 10%.[62] In a complete "well-to-wheel" analysis), which does not take into account economic or market restrictions, General Motors and its partners estimated that, per mile traveled, a vehicle powered by compressed gaseous hydrogen used about one 40% less energy and emitted 45% less greenhouse gases than an internal combustion vehicle.[65] A chief engineer at the Department of Energy whose team is testing fuel cell cars said in 2011 “that their attractive potential lies in the fact that they are fully functional vehicles with no recharging limit and therefore are a direct replacement for any vehicle. For example, if you are driving a maximum-size SUV and want to drag a boat up the mountain, it can be done with this technology and it cannot be done with current vehicles that run only on batteries, which are more designed for urban driving.”[66].
Some experts believe, however, that fuel cell cars will never become economically competitive with other technologies[67][68] or that it will take decades until they become profitable.[69][70] In July 2011, General Motors Chairman and CEO Daniel Akerson said: “The car is still too expensive and probably won't be practical until later in 2020, I don't know” although fuel cell car prices of hydrogen fuel were decreasing.[71].
In 2012, Lux Research, Inc., published an article stating: “The dream of a hydrogen economy…is no closer.” It concluded by saying: “The cost of capital… will limit its adoption to no more than 5.9 GW” in 2030 with an almost “insurmountable barrier to adoption except in very limited market areas.” The analysis concluded by saying that in 2030 the stationary PEM market would reach one trillion dollars while the market for vehicles, including forklifts, a total of two trillion.[72] Other analyzes cite the lack of an extensive hydrogen infrastructure in United States as a challenge for the commercialization of electric fuel cell vehicles. In 2006, a study for IEEE showed that, for hydrogen produced by the electrolysis of water: "Approximately, only 25% of wind, hydro or solar energy has practical use." The study, later, mentioned that: "it appears that the energy obtained from hydrogen fuel cells is four times more expensive than the energy obtained from the grid... Because the high energy losses (hydrogen) cannot compete with electricity" (95). Furthermore, the study stated: The modification of natural gas is not a sustainable solution.”[73] The large amount of energy needed to isolate hydrogen from other natural components (water, natural gas, biomass), store the gas by compression or liquefaction, transfer the energy to the user, plus the loss of energy when it is converted into usable electrical energy through fuel cells leaves around 25% for practical use.[74][75][76].
Portable power systems
Portable power systems based on fuel cells can be used in the leisure sector (e.g. caravans, cabins, boats), the industrial sector (e.g. to power remote gas or oil wells, communication towers, security, weather stations, etc.) and the military sector.[126][127].
Other possible uses
• - Base power plants").
• - Auxiliary Energy Systems[128].
• - Provide power for base radio stations[129].
• - Energy centralization systems").
• - Emergency power systems"), which include lighting, generators and other devices that provide support in critical situations or when normal systems fail. They can be used in many places, from homes to hospitals, research centers and data centers.[130].
• - Telecommunications equipment and modern naval equipment.[131].
• - Uninterruptible power supply system UPS (uninterruptible power supply), provides power in case of emergency and, depending on the topology, regulates the line in addition to the equipment providing power from a separate source when the other is not available. Unlike a standby generator, it provides instant protection against a momentary line interruption.
• - Solar hydrogen fuel cells for water heating.[132].
• - Hybrid vehicles, using, for example, a fuel cell and a battery.
• - Support systems for the electrical network.
• - Portable ports for small electronic instruments (e.g., a belt clip that charges your cell phone or PDA).
• - Smartphones, laptops and tablets.
• - Small heating devices[133].
• - Food preservation, achieved by eliminating oxygen and automatically maintaining the absence of oxygen in a container containing, for example, fresh fish.
• - Breathalyzers, where the voltage generated by the battery is used to determine the concentration of fuel in the sample (alcohol)[134].
Currently, the biggest problems lie in the support and catalysis materials. According to various authors (Venkatachalapathy, Davila et al. 1999), (Hoogers 2003), an electrocatalyst material must satisfy several requirements. It needs, first of all, high efficiency in the electrochemical oxidation of the fuel at the anode, (e.g. H or CH) and for the reduction of O at the cathode. High durability is also a fundamental requirement: PEMFCs are expected to operate for at least 10,000 hours. It is necessary for an electrocatalyst to have good electrical conductivity to minimize resistance losses in the catalyst layer. It must finally have a low production cost.
Economy and Environment
In 2012, fuel cell industry revenues surpassed $1 trillion on the stock market worldwide.[135] However, as late as October 2013, no public company in the industry was yet profitable.[136]140,000 fuel cell stacks were shipped globally in 2010, 11,000 more than in 2007, and since From 2011 to 2012 the shipment growth rate was 85%.[137] Tanaka Kikinzoku Kogyo K.K") increased its facilities for the production of fuel cell catalysts to respond to anticipated demand as Japanese ENE Farm expected to install 50,000 units in 2013[138] and the company is experiencing rapid market growth.
About 50% of fuel cell shipments in 2010 were fuel cells, up from one-third in 2009, and the four dominant producers in the Fuel Cell Industry were the United States, Germany, Japan, and South Korea.[139] The Department of Solid State Energy and the Energy Conversion Alliance found that, as of June 2011, stationary fuel cells generated power at a price of $774 – $775 per installed kilowatt.[140] In 2011, Bloom Energy, a large fuel cell supplier, said its fuel cells generated power at 9-11 cents per kilowatt-hour, including the price of fuel, maintenance and equipment.[141].
Industry groups predict that there are sufficient reserves of platinum for future demand,[142] and in 2007, research conducted at Brookhaven National Laboratory suggested that platinum could be replaced by a coating of gold and palladium, which could be less susceptible to poisoning and therefore lengthen the life of the fuel cell.[143] Another approach could be to use iron and sulfur instead of platinum. This would lower the cost of the batteries (since the platinum in a typical fuel cell costs around US$1,500 and the required iron would cost US$1.50). The concept was being developed by a coalition formed by the John Innes Center and the University of Milan-Bicocca").[144] PEDOT cathodes are immune to monoxide poisoning.[145].
Fuel cells are very attractive for advanced uses due to their high efficiency and ideally (see renewable energies) because they have zero emissions, in contrast to the most common current fuels, such as methane or natural gas, which always generate carbon dioxide. Almost 50% of all electricity produced in the United States comes from coal, which is a highly dirty energy source. If electrolysis is used to create hydrogen using energy from power plants, hydrogen is actually created from coal. Although the fuel cell only emits heat and water as waste, the pollution problem will continue to be present in power plants.
A global approach must consider the impacts caused by the entire hydrogen scenario, including production, use, infrastructure and energy converters. Fuel cells today are oversized with catalyst, to compensate for their own deterioration [8]. The limitation in platinum mineral reserves has led to the search for other solutions, for example the synthesis of an inorganic complex very similar to the iron-sulfide catalytic base of hydrogenase bacteria [9]. The world's platinum reserves would be insufficient (one quarter) of what is needed to allow a complete conversion of vehicles to fuel cells: a significant introduction of vehicles with current technology would therefore cause a large increase in the price of platinum and a significant decrease in its reserves. However, recent work has managed to design iron and nitrogen catalysts as efficient as platinum ones, but with a shorter useful life (100 hours) [10].
Glossary of terms
• - Electrode: End of a conductive body in contact with a medium from which it receives or to which it transmits an electric current[146].
• - Anode: Electrode in which oxidation occurs. For fuel cells and other galvanic cells the anode is the negative terminal; For electrolytic cells (in which electrolysis occurs) the anode is the positive terminal.[147].
• - Cathode: Electrode in which the reduction (gain of electrons) occurs. For fuel cells and other galvanic cells the cathode is the positive terminal; For electrolytic batteries the cathode is the negative terminal.[147].
• - Electrolyte: A substance that conducts charged ions from one electrode to another in a fuel cell, battery, or electrolyzer.[147].
• - Stacking: Individual fuel cells connected in series. Fuel cells are stacked to increase voltage.[147].
• - Solution: A: a process by which a solid, liquid, or gaseous substance is mixed homogeneously with a liquid or, sometimes with a gas or with a solid; B: a homogeneous mixture formed by this process; C: the condition of being dissolved[148].
• - Catalyst: A chemical substance that increases the speed of a reaction without being consumed.[147].
• - Matrix: place from which or within which something originates, develops or takes shape.[149].
• - Membrane&action=edit&redlink=1 "Membrane (selective barrier) (not yet drafted)"): The separation layer in a fuel cell that acts as an electrolyte and as a barrier film that separates gases in the anodic and cathodic compartments of the fuel cell.[147].
Videos about fuel cells
En esta sección se resumirán los principales aspectos referidos a treinta y cinco videos seleccionados y se hará breve una reseña de los mismos. La selección se ha centrado en videos de carácter divulgativo y sobre todo, en los que tratan los aspectos científicos y técnicos de las pilas de combustible. Sin embargo, con el fin de complementar el rigor científico de los otros videos, también se han seleccionado videos cuyas explicaciones son escuetas pero que nos ofrecen una perspectiva visual del dispositivo que estamos tratando y de sus aplicaciones. La lista consta de 11 videos en español y 24 en inglés. El enlace directo a la lista de reproducción es el siguiente:.
Pilas de Combustible.
Videos in Spanish
1º Fuel cells..
• - Direct link.
• - Author: University of Vigo, Prof. Anxo Sánchez Bermúdez.
• - Duration: 19:55 minutes.
• - Description: introduction to fuel cells. It clearly defines this type of device and talks about its different aspects in a general way and without delving into details. However, it must be taken into account that when talking about the characteristics, advantages and disadvantages, he is mainly referring to the hydrogen fuel cell. It is therefore a video of an informative nature and very useful for a first approach to the subject.
2nd Video Series: Hydrogen Energy..
• - Direct link.
• - Author: Polytechnic University of Madrid, made by students.
• - Duration: 1:58 hours.
• - Description: these are nine presentations made by UPM students about hydrogen fuel cells and their different applications; Each presentation focuses on a different aspect. The interest of these videos lies in the fact that they show and analyze a large number of applications that these devices can have. Although they focus on specific aspects and applications, they can generally be understandable for the non-specialized public since very technical details are not usually presented and some of the presentations begin with a short introduction about fuel cells. Below is a description of each of the videos that make up the series:
Stationary applications of the various types of fuel cells: The main characteristics of the different types of fuel cells and their applications in stationary power generation are described.
Automotive applications: The prototypes manufactured by different automobile companies are described: the state of the commercial implementation of automobiles powered by fuel cells is presented.
Portable applications of fuel cells: The choice of fuel in the case of fuel cells used in portable applications is discussed and some prototypes are shown.
Use of hydrogen in aerospace vehicles 1: The scope of application and use of fuel cells in space shuttles and manned and unmanned aircraft is explained.
Use of hydrogen in aerospace vehicles 2: Continues where the previous video ends, complementing it. The types of propulsion of aerospace vehicles using hydrogen are explained: fuel cells, internal combustion engines and hybrid systems. The "Aviazor Project" is detailed.
Projects that develop propulsion of aerospace vehicles with hydrogen: The theme of video 5 continues, describing the different stages and characteristics of the projects, some projects such as: "Ion Tiger", "Solareagle", "Phantom Eye" and "Global Observer".
Applications of fuel cells in the marine environment: An overview is given of what a fuel cell is, its classification and its main advantages. A brief overview of the possible applications of the different types of fuel cells in the marine environment is offered.
Applications of fuel cells in underwater devices: Existing submarines that have fuel cells in their propulsion are described. It explains what an AIP (Air Independent Propulsion) system is. In particular, the S-80 submarine is explained, which will use hydrogen from reformed bioethanol to power PEMFC fuel cells. Unmanned autonomous underwater devices are also described.
Applications of fuel cells in surface ships: Surface vessel projects that incorporate fuel cells in their main propulsion system or to meet electrical consumption or as auxiliary power units are described. The effect of reducing emissions as a consequence of the use of fuel cells in the marine world is studied.
3rd Hydrogen cell..
• - Direct link.
• - Author: Tecnópolis. Presented by Vicente López.
• - Duration: 1:40 minutes.
• - Description: Brief but concise explanation about the hydrogen fuel cell vehicle and the viability of hydrogen as an energy vector, highlighting the environmental advantages of its use.
• - Direct link.
4º Buses with fuel cells..
• - Direct link.
• - Author: CEER Courses.
• - Duration: 1:53 minutes.
• - Description: dynamic explanation with figures and text about the operation of a PEM type fuel cell. The main components are described and their specific location in the stack is shown. Finally, its application is seen in a transport vehicle (bus).
5º Produce electricity through plants..
• - Direct link.
• - Author: Euronews.
• - Duration: 1:58 minutes.
• - Description: This video shows how green plants generate electricity. This is the Plant-e project of Wageningen University in the Netherlands. The microbial plant fuel cell generates electricity from the natural interaction between plant roots and soil bacteria. It works by taking advantage of up to 70% of organic material produced through photosynthesis that is not used by the plant and is secreted by the roots. The bacteria that are next to the roots interact with the organic waste, releasing electrons. And this is how electricity is generated: by placing an electrode that absorbs the released electrons.
6º Fuel cells..
• - Direct link.
• - Author: Polytechnic University of Valencia, Javier Orozco Messana.
• - Duration: 11:01 minutes.
• - Description: This is an introduction to fuel cells. It starts with a brief definition. Continue with a historical tour. Subsequently, it focuses on operation, taking a hydrogen cell as an example and then talks about the other types of batteries.
Videos in English
1º How does a fuel cell work?.
• - Direct link.
• - Author: Naked Science Scrapbook.
• - Duration: 4:01 min.
• - Description: Introduction to fuel cells. The explanations are made through drawings in a notebook accompanied by a voice-over. It begins by announcing them as the possible technology of the future and refers to their possible applications on different devices. It explains its operating principles using a hydrogen cell as an example and then explains the operation and applications of PEMFCs, AFCs and SOFCs. He repeatedly alludes to the advantages that these devices offer over traditional methods of obtaining electricity.
2º How a fuel cell works?.
• - Direct link.
• - Author: University of Waterloo Alternative Fuel Cell Team.
• - Duration: 1:51 minutes.
• - Description: informative explanation about the operation of the hydrogen fuel cell car. Its location inside the vehicle is shown, as well as that of the fuel. The operation is explained, what happens within an individual cell through an animation.
3ºBuilding a Fuel Cell Stack..
• - Direct link.
• - Author: Schatz Energy Research Center.
• - Duration: 11:05 minutes.
• - Description: this video shows the assembly process of a PEM type fuel cell stack. It begins by briefly explaining the operating mechanism of a fuel cell of this type. Finally, we are shown how to assemble it step by step, all accompanied by the relevant explanations.
4th OWI's Salt Water Fuel Cell Car..
• - Direct link.
• - Author: ABC News.
• - Duration: 1:45 minutes.
• - Description: The video shows a toy car whose fuel is salt water that can run continuously for 5 to 7 hours. This car gives both children and adults the opportunity to learn about forms of clean energy.
5th Toyota's Fuel Cell Vehicle: A Zero-Emission Car Coming 2015!.
• - Direct link.
• - Author: DNews.
• - : 3:27 minutes.
General
Literature
• - Gregor Hoogers, Hoogers Hoogers - Fuel Cell Technology Handbook - Publisher:CRC Press January 2003 - ISBN 0-8493-0877-1.
• - Venkatachalapathy, R., G. P. Davila, et al. (1999). "Catalytic decomposition of hydrogen peroxide in alkaline solutions." Electrochemistry Communications 1:614-617.
• - Wikimedia Commons hosts a multimedia gallery on Fuel Cell.
• - Fuel Cells (animations).
• - Fuel Cells.
• - Fuel Cell or Cell, Short video from the Discovery Channel.
[2] ↑ Life cycle assessment of PEM FC applications: electric mobility and μ-CHP. Dominic A. Notter,*a Katerina Kouravelou,b Theodoros Karachalios,b Maria K. Daletouc and Nara Tudela Haberlandad; Energy Environ. Sci., 2015,8, 1969-1985 DOI: 10.1039/C5EE01082A.
[3] ↑ Fuel Cell Hand Book. EG&G Technical Services, Inc. 2004. ISBN 9780442319267.
[4] ↑ Enciclopedia de los niños. Printer Latinoamérica, LTDA. 1990. ISBN ISBN 958-28-0193-X (Colección) / ISBN 958-28-0195-6 (Tomo 2) |isbn= incorrecto (ayuda).
[7] ↑ Pilas de combustible: una alternativa limpia de producción de energía Ricardo Escudero-Cid, Enrique Fatás, Juan Carlos Pérez-Flores y Pilar Ocón,2013.
[9] ↑ Grove, William Robert. "On Voltaic Series and the Combination of Gases by Platinum", Philosophical Magazine and Journal of Science vol. XIV (1839), pp. 127–130.
[10] ↑ a b Fuel Cell Technology Handbook. CRC Press. 2002. ISBN 9781420041552.
[11] ↑ Bacon, F.T., Research into the properties of the hydrogen-oxygen fuel cell, BEAMA Journal, 61, 6–12, 1954.
[18] ↑ CORPORATION, TOYOTA MOTOR. «Toyota Launches the New Mirai | Toyota | Global Newsroom». Toyota Motor Corporation Official Global Website (en inglés). Consultado el 23 de octubre de 2025.: https://global.toyota/en/newsroom/toyota/33558148.html
[21] ↑ A.J. Appleby, F.R. Foulkes, Fuel Cell Handbook, Van Nostrand Reinhold, New York, NY,1989.
[22] ↑ Performance of non-porous graphite and titanium-based anodes in microbial fuel cells Annemiek ter Heijne, Hubertus V.M. Hamelers, Michel Saakes, Cees J.N. Buisman. 2008.
[23] ↑ REVIEWS ON SOLID OXIDE FUEL CELL TECHNOLOGY,Navadol Laosiripojanaa, Wisitsree Wiyaratnb,Worapon Kiatkittipongc, Arnornchai Arpornwichanopd,Apinan Soottitantawatd, and Suttichai Assabumrungratd,2009.
[24] ↑ a b c d e f g h i Fuel Cell HandBook, Seventh Edition, EG&G Technical Services, Inc., 2004.
[27] ↑ Gottesfeld, S. and Pafford, J., A new approach to the problem of carbon monoxide poisoning in fuel cells operating at low temperatures, Journal of the Electrochemical Society, 135, 2651–2652, 1988.
[28] ↑ Pilas de combustible: una alternativa limpia de producción de energía Ricardo Escudero-Cid, Enrique Fatás, Juan Carlos Pérez-Flores y Pilar Ocón,2013.
[34] ↑ a b S.N. Simons, R.B. King and P.R. Prokopius, in Symposium Proceedings Fuel Cells Technology Status and Applications, Figure 1, p. 46, Edited by E.H. Camara, Institute of Gas Technology, Chicago, IL, 45, 1982.
[35] ↑ a b c d e F. Barbir, PEM fuel cell, ELSEVIER, 2005.
[36] ↑ Fundamentos de transferencia de calor, Frank P.Incropera, David P. DeWitt, Pearson Educación, 1999.
[37] ↑ Fuchs, M. and F. Barbir, Development of Advanced, Low-Cost PEM Fuel Cell Stack and System Design for Operation on Reformate Used in Vehicle Power Systems, Transportation Fuel Cell Power Systems, 2000 Annual Progress Report (U.S. Department of Energy, Office of Advanced Automotive Technologies, Washington, D.C., October 2000) pp. 79-84.
[40] ↑ "Fuel Cell Basics: Applications" Archivado el 15 de mayo de 2011 en Wayback Machine. Fuel Cells 2000. Accessed 2 August 2011.: http://www.fuelcells.org/basics/apps.html
[41] ↑ a b c "Types of Fuel Cells". Department of Energy EERE website, accessed 4 August 2011 http://energy.gov/eere/fuelcells/fuel-cells.: http://energy.gov/eere/fuelcells/fuel-cells
[43] ↑ "2008 Fuel Cell Technologies Market Report" Archivado el 4 de septiembre de 2012 en Wayback Machine.. Bill Vincent of the Breakthrough Technologies Institute, Jennifer Gangi, Sandra Curtin, and Elizabeth Delmont. Department of Energy Energy Efficiency and Renewable Energy. June 2010.: http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/48219.pdf
[44] ↑ U.S. Fuel Cell Council Industry Overview 2010, p. 12. U.S. Fuel Cell Council. 2010.
[57] ↑ H.I. Onovwiona and V.I. Ugursal. Residential cogeneration systems: review of the current technology. Renewable and Sustainable Energy Reviews, 10(5):389 – 431, 2006.
[58] ↑ AD. Hawkes, L. Exarchakos, D. Hart, MA. Leach, D. Haeseldonckx, L. Cosijns and W. D’haeseleer. EUSUSTEL work package 3: Fuell cells, 2006.
[61] ↑ Wipke, Keith, Sam Sprik, Jennifer Kurtz and Todd Ramsden. "Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project" Archivado el 16 de octubre de 2011 en Wayback Machine.. National Renewable Energy Laboratory, 11 September 2009, accessed on 2 August 2011.: http://www.nrel.gov/hydrogen/pdfs/46679.pdf
[63] ↑ Wipke, Keith, Sam Sprik, Jennifer Kurtz and Todd Ramsden. "National FCEV Learning Demonstration" Archivado el 19 de octubre de 2011 en Wayback Machine.. National Renewable Energy Laboratory, April 2011, accessed 2 August 2011.: http://www.nrel.gov/hydrogen/pdfs/51564.pdf
[65] ↑ Brinkman, Norma, Michael Wang, Trudy Weber and Thomas Darlington. "Well-To-Wheels Analysis of Advanced Fuel/Vehicle Systems – A North American Study of Energy Use, Greenhouse Gas Emissions, and Criteria Pollutant Emissions". General Motors Corporation, Argonne National Laboratory and Air Improvement Resource, Inc., May 2005, accessed 9 August 2011.: http://www.transportation.anl.gov/pdfs/TA/339.pdf
[72] ↑ Brian Warshay, Brian. "The Great Compression: the Future of the Hydrogen Economy", Lux Research, Inc. January 2013.
[73] ↑ Bossel, Ulf. "Does a Hydrogen Economy Make Sense? Proceedings of the IEEE Vol. 94, No. 10, October 2006.
[74] ↑ Meyers, Jeremy P. "Getting Back Into Gear: Fuel Cell Development After the Hype". The Electrochemical Society Interface, Winter 2008, pp. 36–39, accessed 7 August 2011.
[75] ↑ Eberle, Ulrich and Rittmar von Helmolt. "Sustainable transportation based on electric vehicle concepts: a brief overview". Energy & Environmental Science, Royal Society of Chemistry, 14 May 2010, accessed 2 August 2011.
[76] ↑ Zyga, Lisa. "Why a hydrogen economy doesn't make sense". physorg.com, 11 December 2006, accessed 2 August 2011, citing Bossel, Ulf. "Does a Hydrogen Economy Make Sense?" Proceedings of the IEEE. Vol. 94, No. 10, October 2006.
[77] ↑ Kubota, Yoko. "Toyota says slashes fuel cell costs by nearly $1 million for new hydrogen car". Reuters, Oct 10, 2013.
[78] ↑ Lienert, Anita. "Mercedes-Benz Fuel-Cell Car Ready for Market in 2014". Edmunds Inside Line, 21 June 2011.
[79] ↑ Korzeniewski, Jeremy (27 September 2012). "Hyundai ix35 lays claim to world's first production fuel cell vehicle title". autoblog.com. Retrieved 2012-10-07.
[80] ↑ "GM's Fuel Cell System Shrinks in Size, Weight, Cost". General Motors. 16 March 2010. Retrieved 5 March 2012.
[81] ↑ "Honda unveils FCX Clarity advanced fuel cell electric vehicle at motor show in US". Honda Worldwide. Retrieved 5 March 2012.
[82] ↑ "Environmental Activities: Nissan Green Program 2016". Nissan. Retrieved 5 March 2012.
[83] ↑ Chu, Steven. "Winning the Future with a Responsible Budget". U.S. Dept. of Energy, 11 February 2011.
[84] ↑ Matthew L. Wald (7 May 2009). "U.S. Drops Research into Fuel Cells for Cars". The New York Times. Retrieved 2009-05-09.
[85] ↑ Bullis, Kevin. "Q & A: Steven Chu", Technology Review, 14 May 2009.
[86] ↑ Steven Chu turns out to be a supporter of Hydrogen Technologies – on 2.10 min.
[87] ↑ Motavalli, Jim. "Cheap Natural Gas Prompts Energy Department to Soften Its Line on Fuel Cells", The New York Times, 29 May 2012.
[88] ↑ "Transportation Fleet Vehicles: Overview". UTC Power. Accessed 2 August 2011.
[89] ↑ "FY 2010 annual progress report: VIII.0 Technology Validation Sub-Program Overview".John Garbak. Department of Energy Hydrogen Program.
[90] ↑ a b "National Fuel Cell Bus Program Awards". Calstart. Accessed 12 August 2011.
[91] ↑ "Fuel cell buses". Transport for London. Archived from the original on 13 May 2007. Retrieved 2007-04-01.
[92] ↑ "Ônibus brasileiro movido a hidrogênio começa a rodar em São Paulo" (in Portuguese). Inovação Tecnológica. 8 April 2009. Retrieved 2009-05-03.
[147] ↑ a b c d e f "Fuel Cell Technologies Program: Glossary" Archivado el 23 de febrero de 2014 en Wayback Machine.. Department of Energy Energy Efficiency and Renewable Energy Fuel Cell Technologies Program. 7 July 2011. Accessed 3 August 2011.: http://www1.eere.energy.gov/hydrogenandfuelcells/glossary.html#c
In "combined heat and power uses" (cogeneration), for applications where heat energy is also required, a lower fuel-to-electricity conversion efficiency is accepted (typically 15-20%), because most of the energy not converted to electricity is used as heat. Some heat is lost with the gases leaving the cell as occurs in any conventional boiler, so with this combined production of thermal energy and electrical energy the efficiency is still lower than 100%, normally around 80%. In terms of energy however, the process is inefficient, and better energy results would be obtained by maximizing the electricity generated and then using the electricity to run a heat pump.
• - Increase in the concentration of the reactants.
• - Higher operating pressures.
Ohmic losses are due to resistance to the flow of ions in the electrolyte and resistance to the flow of electrons traveling through the electrode. The electrodes and electrolyte are usually fundamentally ohmic materials, that is, materials in which the linear behavior of voltage versus current intensity predominates. Therefore, ohmic losses can be expressed through Ohm's law:.
where I is the current flowing through the cell and R is the total resistance, which includes that due to electrons, that due to ions and that due to contact terminals and connections:.
Depending on the geometry of the fuel cell, the contribution to the total resistance of each of these resistances varies.[35] Thus, in a SOFC-type fuel cell with a flat structure, the ionic resistance dominates, while in a tubular-type SOFC, that due to the passage of electrons dominates.
The factors that reduce ohmic losses are, according to Barbir:[35].
• - Use electrodes made of a material with high electrical conductivity.
• - Carry out a good structural design, minimizing current paths.
• - Use of thin ionic membranes.
When mass transport occurs at a finite speed in the electrode, the entry of reactive gas and the correct evacuation of the products are limited, therefore, it often happens that the gas inside is consumed, diluting itself in the products. As a consequence, a concentration gradient is created between the electrode surface and the supply inputs, which negatively contributes to the output potential.
The rate of mass transport to the surface of an electrode can be described by Fick's diffusion law:[36].
Where D is the diffusion coefficient of the reactants, C its maximum concentration, C its surface concentration and δ is the thickness of the diffusion layer. The limiting current, I, is a measure of the maximum rate at which the reagent can be delivered to the electrode and this occurs when C=0. Therefore:.
Then we can express the concentrations in the following way:.
Therefore, the Nernst equation for chemical species under equilibrium conditions, or in open circuit, is:
When there is current flow, the surface concentration is less than the maximum concentration, and the Nernst equation becomes.
The potential difference that is produced by a change in concentration at the electrode, ΔE, is known as concentration polarization:.
or depending on the limit current:.
To reduce this type of losses Barbir[35] gives the following indications:
• - Frequently purify the water content in the cathode so that the gases can diffuse properly.
• - Increase the operating temperature so that the accumulated water evaporates and thus reduces the blocking of the gases that are supplied.
Despite this, several major car manufacturers have announced plans to introduce production of a fuel cell car model in 2015. In 2013, Toyota has stated that it plans to introduce such a vehicle for a price under $100,000.[77] Mercedes-Benz announced that it will move the scheduled production date for its fuel cell car from 2015 to 2014, stating that: "the vehicle is technically ready for the market….the problem is one of infrastructure.”[78] At the Paris Motor Show in September 2012, Hyundai announced that it planned to begin commercial production of a fuel cell model (based on the ix35) in December 2012 and that it expected to deliver 1,000 units in 2015.[79] Other manufacturers that plan to have fuel cell vehicles ready by 2016 or earlier are General Motors,[80] Honda[81] in Japan and Nissan.[82].
Former President Obama's Administration reduced funding for the development of fuel cell vehicles, arguing that other automotive technologies would achieve greater emissions reductions in less time.[83] Steven Chu, United States Secretary of Energy, announced in 2009 that hydrogen vehicles “will not be practical for the next 10 to 20 years.”[84][85] However, in 2012, Chu stated that he saw fuel cell cars. more viable fuel as natural gas prices had fallen and hydrogen modification technologies had improved.[86][87].
As of 2011 there are a total of approximately 100 fuel cell powered buses distributed around the world. Most buses are manufactured by UTC Power, Toyota, Ballard, Hydrogenics, and Proton Motor. UTC buses have since traveled 970,000 km.[88] Fuel cell buses improve fuel efficiency over diesel and natural gas buses by around 39%-141%.[89] Fuel cell buses have been distributed in places such as: Whistler, Canada; San Francisco, United States; Hamburg, Germany; Shanghai, China; London, England; Sao Paulo, Brazil; and elsewhere[90] The Fuel Cell Bus Club is a global cooperative effort to test fuel cell buses. Other notable projects include:.
• - 12 buses have been distributed in Oakland and the San Francisco Bay area in California[90].
• - Daimler AG, with 36 experimental buses powered by Ballard Fuel Cell Energy Systems, successfully completed a three-year trial in 11 cities in June 2007.[91].
The first Brazilian bus prototype with hydrogen fuel cells was used in Sao Paulo. It was manufactured in Caxias do Sul and hydrogen produced in Sao Bernardo do Campo from water through electrolysis. The program, called "Ônibus Brasileiro a Hidrogênio", includes three additional buses.[92].
A fuel cell forklift (also called a fuel cell lift truck) is an industrial forklift powered by a fuel cell used to lift and transport materials. Most batteries used for materials handling are powered by PEM fuel cells.
In 2013, more than 4,000 such forklifts were in use in the United States,[93] of which only 500 received funding from the DOE (2012).[94] Fuel cell fleets are operated by a large number of companies, including: Sysco Foods"), Fedex Freight"), GENCO (Wegmans"), Coca-Cola, Kimberly Clark, and Whole Foods), and H-E-B). Grocers"). 30 Hylift fuel cell forklifts were operating in Europe. This number rose to 200 units with HyLIFT-EUROPE"),[95] with projects in France[96][97] and Austria.[98] Pike Research announced in 2011 that fuel cell-powered forklifts would be the largest driver of hydrogen demand in 2020.[99].
Forklifts powered by PEM fuel cells have important advantages over those powered by oil and batteries since they do not produce local emissions, can work an 8-hour shift in a row with a single tank of hydrogen, can be recharged in 3 minutes and have a lifespan of 8-10 years. They are usually used in refrigerated warehouses since their performance is not affected by low temperatures. Many companies are not using oil-powered forklifts as these vehicles are used indoors where emissions must be controlled and are instead moving to electric forklifts.[100] By design the fuel cells are manufactured so that they can be replaced immediately.[101][102].
In 2005, an English hydrogen fuel cell manufacturer, Intelligent Energy" (IE), produced the first hydrogen-powered motorcycle, called the ENV" (Neutral Emission Vehicle). The motorcycle stores enough fuel to run for 4 hours and travel 160 km in an urban area, at a maximum speed of 80 km/h.[103] In 2004, Honda developed a fuel cell-based motorcycle that used a stack of Honda fuel cells.[104][105].
Other examples of motorcycles[106] and bicycles[107] that use hydrogen fuel cells are the scooter from Taiwanese company APFCT") which uses the fuel system from Italy's Acta Spa")[108] and Suzuki's Burgman scooter with an IE fuel cell") which received EU Whole Vehicle Type Approval") in 2011.[109] Suzuki Motor Corp and IE have announced a joint venture to accelerate commercialization of zero emission vehicles.[110].
In 2003, the first (unmanned) aircraft powered entirely by fuel cells made its first flight. The fuel cell was a single flatstack design, which allowed it to be integrated into the aerodynamic surfaces of the aircraft.[111]
There have been several fuel cell unmanned aerial vehicles (UAVs). A Horizon Fuel Cell UAV set the flight distance record for a small UAV in 2007.[112].
Researchers at Boeing and other business partners in Europe conducted test flights in February 2008 with a manned aircraft powered solely by a fuel cell and light batteries. The so-called "fuel cell demonstrator aircraft" used a hybrid system composed of a PEM fuel cell and a lithium ion battery to propel an electric motor coupled to a conventional propeller. In April 2008, in Toledo (Spain), the Boeing company flew the first aircraft powered by a hydrogen cell.
The military is especially interested in this application because of its low noise, low heat output, and its ability to reach high altitudes. In 2009, the Naval Research Laboratory's (NRL) Ion Tiger made a 23-hour, 17-minute flight using a hydrogen fuel cell.[115] Fuel cells are also being used to provide additional power in aircraft, replacing the fossil fuel generators previously used to power engines and provide on-board power.[116] Aircraft powered by fuel cells can help reduce polluting emissions and of noise.[117].
The first HYDRA fuel cell ship used an AFC system with a net power output of 6.5 kW. Iceland has committed to converting its vast fleet of fishing boats to boats that use fuel cells to provide auxiliary power by 2015 and eventually to provide primary power. Amsterdam has recently introduced the first fuel cell-powered passenger ferry that runs along the city's famous canals.[118].
Currently, a team of university students called Energy-Quest is preparing a boat powered by this technology to make a trip around the world, as well as other projects using more efficient or renewable fuels. His company is called Triton.
The Type 212A submarines, an advanced German non-nuclear submarine design, use fuel cells (developed by Siemens) to power nine thrusters and can remain submerged for weeks without having to surface.[119] The system consists of 9 PEM fuel cells, providing between 30 kW and 50 kW each. It is silent, which gives it an advantage in detecting other submarines.[120].
A similar hydrogen fuel cell propulsion system, although improved, has the Spanish S-80 submarines developed by Abengoa.
The first hydrogen fueling station was opened in Reykjavík, Iceland in April 2003. This station supplies three buses built by DaimlerChrysler and serving the Reykjavík public transport network. The station itself produces the hydrogen it needs, thanks to an electrolyser unit (manufactured by Norsk Hydro), and does not need to be supplied externally: the only supplies needed are electricity and water. Shell is also involved in the project. The station does not have a cover, so that in case of danger the hydrogen can escape freely into the atmosphere.
In 2010 there were 85 hydrogen plants in the United States.[121] In 2012, California had 23 hydrogen plants in operation.[121][122] Honda announced, in March 2011, that it planned to open the first station that would generate hydrogen through electrolysis produced by solar energy. South Carolina also has two hydrogen stations, in Aike and Columbia respectively. The University of South Carolina, a founding member of the South Carolina Hydrogen and Fuel Cell Alliance, received $12.5 million from the U.S. Department of Energy for its Future Fuels Program.[123]
The 14 German stations are planned to reach 50 by 2015[124] through their public-private collaboration Now-GMBH.[125] Japan has a hydrogen highway, as part of the Japanese Hydrogen Fuel Cell Project.
Duration
• - Description: This video shows a hydrogen fuel cell vehicle that will be on the market in 2015. The senior engineer at Toyota Fuel Cell Group is interviewed, who gives a brief explanation of what a hydrogen fuel cell is and briefly describes the operation of a hydrogen vehicle and the difference between it and hybrid vehicles. It is emphasized that it is a clean technology. from the environmental point of view.
6th Virtual Fuel Cell Interactive Visualization..
• - Direct link.
• - Author: NASA Glenn Graphics and Visualization Lab.
• - Duration: 1:36 minutes.
• - Description: video made from a simulation program for a tubular configuration fuel cell. The simulation allows us to control the amount of impurities in the fuel, thus showing how a high amount of these directly affects the operation of the cell. You can also control the speed of the simulation and the output power of the stack.
7th Video Series: Introduction to the Fuel Cell..
• - Direct link.
• - Author: Polytechnic University of Valencia: María Desamparados Ribes Greus.
• - Duration:1:59:41 hours.
• - Description: in this series of videos there is a complete analysis of the operation of fuel cells. Practically all the topics presented in this report are covered from a scientific-technical point of view, the explanations are made in a clear and, to the extent that the specialization of the topic allows it, informative. This is a complete introductory guide, which is why the entire series has been included.
Main Aspect: the fundamental aspects and properties of fuel cells are presented; focuses on its role in the renewable energy environment. Several general aspects of fuel cells are discussed as an introduction: their electrochemistry, their basic structure, their main characteristics and their applications. The following videos will delve into the aforementioned topics.
Electrochemical Basis of Fuel Cells: they deal, in greater depth, with the electrochemical foundations of the operation of fuel cells and electric batteries and the bases for solving problems for the calculation of electrical potential.
Main Components of a Fuel Cell: This video shows the main components (in your opinion) of a fuel cell, the electrode and the electrolyte, and describes their functions. Finally, it talks about the other components found in these devices.
General criteria for the classification of fuel cells: This video has a different name in the playlist: "Power Plants". However, the name of the presentation is what has been put at the beginning. Fuel cells are classified by their operating temperature and then the types of electrolyte they can use are discussed.
Fuels: as its name indicates, this video presents the fuels most commonly used in fuel cells.
Proton exchange membrane fuel cells: the basic characteristics of PEMFCs, their components and their operation are explained.
Transport in PEMFC: the transport phenomena that take place inside a fuel cell are explained. The passage of the fuel through the anode (and the oxidizer through the cathode) where we have platinum particles (catalyst) and through the electrolyte is seen. Subsequently, the phenomena that take place in the polymeric membrane are described.
Fuel cell power plant: a brief review of the operation of an individual cell is given and then gives way to explaining what a stack is and its inclusion in a power plant.
Fuels. Hydrogen: describes the main characteristics of hydrogen as a fuel, highlighting those that make it environmentally attractive. It also points out the inconveniences associated with its extraction, transportation and danger of explosion.
Applications of fuel cells: as its name indicates, the video is about the different applications in which fuel cells are used. It starts by talking about the general features and then gives way to the fixed applications. Finally, we talk about portable applications.
Deviations from ideal Behavior: the phenomena that cause the reduction in efficiency that occurs in fuel cells in operation are explained, comparing their operation with the ideal. The expressions that allow describing and predicting its behavior are presented.
Overpotential: describes the different types of losses, activation, resistive and concentration, associated with the different regions of the fuel cell polarization curve.
Direct Methanol Fuel Cells: methanol fuel cells (DMFC) and ethanol fuel cells are presented. Its foundations and the advantages and limitations of its use compared to other fuel cells are discussed, mostly comparing it with PEM.
Alkaline Fuel Cell: describes the operation of the alkaline fuel cell. It talks about their advantages and disadvantages and compares them with other types of fuel cells. Its most common applications are also presented.
8º Compact, high-power hydrogen fuel cell for release in spring 2013.
• - Direct link.
• - Author: Digiinfo TV.
• - Duration: 2:46 minutes.
• - Description: the video shows us different types of fuel cells designed by Kyoto University applicable to both devices with low power requirements (mobile phones, laptops, etc.) and media (plasma televisions) and even with high powers that allow powering several devices simultaneously or generating electricity for a home.
• - Hydrogen.
• - Hydrogen.
• - Hydrogen economy.
• - Methanol (fuel) "Methanol (fuel)").
• - Methanol.
• - Ethanol (fuel) "Ethanol (fuel)").
• - Ethanol.
• - Biofuel
Biodiesel
Bioethanol
Hemp.
In "combined heat and power uses" (cogeneration), for applications where heat energy is also required, a lower fuel-to-electricity conversion efficiency is accepted (typically 15-20%), because most of the energy not converted to electricity is used as heat. Some heat is lost with the gases leaving the cell as occurs in any conventional boiler, so with this combined production of thermal energy and electrical energy the efficiency is still lower than 100%, normally around 80%. In terms of energy however, the process is inefficient, and better energy results would be obtained by maximizing the electricity generated and then using the electricity to run a heat pump.
• - Increase in the concentration of the reactants.
• - Higher operating pressures.
Ohmic losses are due to resistance to the flow of ions in the electrolyte and resistance to the flow of electrons traveling through the electrode. The electrodes and electrolyte are usually fundamentally ohmic materials, that is, materials in which the linear behavior of voltage versus current intensity predominates. Therefore, ohmic losses can be expressed through Ohm's law:.
where I is the current flowing through the cell and R is the total resistance, which includes that due to electrons, that due to ions and that due to contact terminals and connections:.
Depending on the geometry of the fuel cell, the contribution to the total resistance of each of these resistances varies.[35] Thus, in a SOFC-type fuel cell with a flat structure, the ionic resistance dominates, while in a tubular-type SOFC, that due to the passage of electrons dominates.
The factors that reduce ohmic losses are, according to Barbir:[35].
• - Use electrodes made of a material with high electrical conductivity.
• - Carry out a good structural design, minimizing current paths.
• - Use of thin ionic membranes.
When mass transport occurs at a finite speed in the electrode, the entry of reactive gas and the correct evacuation of the products are limited, therefore, it often happens that the gas inside is consumed, diluting itself in the products. As a consequence, a concentration gradient is created between the electrode surface and the supply inputs, which negatively contributes to the output potential.
The rate of mass transport to the surface of an electrode can be described by Fick's diffusion law:[36].
Where D is the diffusion coefficient of the reactants, C its maximum concentration, C its surface concentration and δ is the thickness of the diffusion layer. The limiting current, I, is a measure of the maximum rate at which the reagent can be delivered to the electrode and this occurs when C=0. Therefore:.
Then we can express the concentrations in the following way:.
Therefore, the Nernst equation for chemical species under equilibrium conditions, or in open circuit, is:
When there is current flow, the surface concentration is less than the maximum concentration, and the Nernst equation becomes.
The potential difference that is produced by a change in concentration at the electrode, ΔE, is known as concentration polarization:.
or depending on the limit current:.
To reduce this type of losses Barbir[35] gives the following indications:
• - Frequently purify the water content in the cathode so that the gases can diffuse properly.
• - Increase the operating temperature so that the accumulated water evaporates and thus reduces the blocking of the gases that are supplied.
Despite this, several major car manufacturers have announced plans to introduce production of a fuel cell car model in 2015. In 2013, Toyota has stated that it plans to introduce such a vehicle for a price under $100,000.[77] Mercedes-Benz announced that it will move the scheduled production date for its fuel cell car from 2015 to 2014, stating that: "the vehicle is technically ready for the market….the problem is one of infrastructure.”[78] At the Paris Motor Show in September 2012, Hyundai announced that it planned to begin commercial production of a fuel cell model (based on the ix35) in December 2012 and that it expected to deliver 1,000 units in 2015.[79] Other manufacturers that plan to have fuel cell vehicles ready by 2016 or earlier are General Motors,[80] Honda[81] in Japan and Nissan.[82].
Former President Obama's Administration reduced funding for the development of fuel cell vehicles, arguing that other automotive technologies would achieve greater emissions reductions in less time.[83] Steven Chu, United States Secretary of Energy, announced in 2009 that hydrogen vehicles “will not be practical for the next 10 to 20 years.”[84][85] However, in 2012, Chu stated that he saw fuel cell cars. more viable fuel as natural gas prices had fallen and hydrogen modification technologies had improved.[86][87].
As of 2011 there are a total of approximately 100 fuel cell powered buses distributed around the world. Most buses are manufactured by UTC Power, Toyota, Ballard, Hydrogenics, and Proton Motor. UTC buses have since traveled 970,000 km.[88] Fuel cell buses improve fuel efficiency over diesel and natural gas buses by around 39%-141%.[89] Fuel cell buses have been distributed in places such as: Whistler, Canada; San Francisco, United States; Hamburg, Germany; Shanghai, China; London, England; Sao Paulo, Brazil; and elsewhere[90] The Fuel Cell Bus Club is a global cooperative effort to test fuel cell buses. Other notable projects include:.
• - 12 buses have been distributed in Oakland and the San Francisco Bay area in California[90].
• - Daimler AG, with 36 experimental buses powered by Ballard Fuel Cell Energy Systems, successfully completed a three-year trial in 11 cities in June 2007.[91].
The first Brazilian bus prototype with hydrogen fuel cells was used in Sao Paulo. It was manufactured in Caxias do Sul and hydrogen produced in Sao Bernardo do Campo from water through electrolysis. The program, called "Ônibus Brasileiro a Hidrogênio", includes three additional buses.[92].
A fuel cell forklift (also called a fuel cell lift truck) is an industrial forklift powered by a fuel cell used to lift and transport materials. Most batteries used for materials handling are powered by PEM fuel cells.
In 2013, more than 4,000 such forklifts were in use in the United States,[93] of which only 500 received funding from the DOE (2012).[94] Fuel cell fleets are operated by a large number of companies, including: Sysco Foods"), Fedex Freight"), GENCO (Wegmans"), Coca-Cola, Kimberly Clark, and Whole Foods), and H-E-B). Grocers"). 30 Hylift fuel cell forklifts were operating in Europe. This number rose to 200 units with HyLIFT-EUROPE"),[95] with projects in France[96][97] and Austria.[98] Pike Research announced in 2011 that fuel cell-powered forklifts would be the largest driver of hydrogen demand in 2020.[99].
Forklifts powered by PEM fuel cells have important advantages over those powered by oil and batteries since they do not produce local emissions, can work an 8-hour shift in a row with a single tank of hydrogen, can be recharged in 3 minutes and have a lifespan of 8-10 years. They are usually used in refrigerated warehouses since their performance is not affected by low temperatures. Many companies are not using oil-powered forklifts as these vehicles are used indoors where emissions must be controlled and are instead moving to electric forklifts.[100] By design the fuel cells are manufactured so that they can be replaced immediately.[101][102].
In 2005, an English hydrogen fuel cell manufacturer, Intelligent Energy" (IE), produced the first hydrogen-powered motorcycle, called the ENV" (Neutral Emission Vehicle). The motorcycle stores enough fuel to run for 4 hours and travel 160 km in an urban area, at a maximum speed of 80 km/h.[103] In 2004, Honda developed a fuel cell-based motorcycle that used a stack of Honda fuel cells.[104][105].
Other examples of motorcycles[106] and bicycles[107] that use hydrogen fuel cells are the scooter from Taiwanese company APFCT") which uses the fuel system from Italy's Acta Spa")[108] and Suzuki's Burgman scooter with an IE fuel cell") which received EU Whole Vehicle Type Approval") in 2011.[109] Suzuki Motor Corp and IE have announced a joint venture to accelerate commercialization of zero emission vehicles.[110].
In 2003, the first (unmanned) aircraft powered entirely by fuel cells made its first flight. The fuel cell was a single flatstack design, which allowed it to be integrated into the aerodynamic surfaces of the aircraft.[111]
There have been several fuel cell unmanned aerial vehicles (UAVs). A Horizon Fuel Cell UAV set the flight distance record for a small UAV in 2007.[112].
Researchers at Boeing and other business partners in Europe conducted test flights in February 2008 with a manned aircraft powered solely by a fuel cell and light batteries. The so-called "fuel cell demonstrator aircraft" used a hybrid system composed of a PEM fuel cell and a lithium ion battery to propel an electric motor coupled to a conventional propeller. In April 2008, in Toledo (Spain), the Boeing company flew the first aircraft powered by a hydrogen cell.
The military is especially interested in this application because of its low noise, low heat output, and its ability to reach high altitudes. In 2009, the Naval Research Laboratory's (NRL) Ion Tiger made a 23-hour, 17-minute flight using a hydrogen fuel cell.[115] Fuel cells are also being used to provide additional power in aircraft, replacing the fossil fuel generators previously used to power engines and provide on-board power.[116] Aircraft powered by fuel cells can help reduce polluting emissions and of noise.[117].
The first HYDRA fuel cell ship used an AFC system with a net power output of 6.5 kW. Iceland has committed to converting its vast fleet of fishing boats to boats that use fuel cells to provide auxiliary power by 2015 and eventually to provide primary power. Amsterdam has recently introduced the first fuel cell-powered passenger ferry that runs along the city's famous canals.[118].
Currently, a team of university students called Energy-Quest is preparing a boat powered by this technology to make a trip around the world, as well as other projects using more efficient or renewable fuels. His company is called Triton.
The Type 212A submarines, an advanced German non-nuclear submarine design, use fuel cells (developed by Siemens) to power nine thrusters and can remain submerged for weeks without having to surface.[119] The system consists of 9 PEM fuel cells, providing between 30 kW and 50 kW each. It is silent, which gives it an advantage in detecting other submarines.[120].
A similar hydrogen fuel cell propulsion system, although improved, has the Spanish S-80 submarines developed by Abengoa.
The first hydrogen fueling station was opened in Reykjavík, Iceland in April 2003. This station supplies three buses built by DaimlerChrysler and serving the Reykjavík public transport network. The station itself produces the hydrogen it needs, thanks to an electrolyser unit (manufactured by Norsk Hydro), and does not need to be supplied externally: the only supplies needed are electricity and water. Shell is also involved in the project. The station does not have a cover, so that in case of danger the hydrogen can escape freely into the atmosphere.
In 2010 there were 85 hydrogen plants in the United States.[121] In 2012, California had 23 hydrogen plants in operation.[121][122] Honda announced, in March 2011, that it planned to open the first station that would generate hydrogen through electrolysis produced by solar energy. South Carolina also has two hydrogen stations, in Aike and Columbia respectively. The University of South Carolina, a founding member of the South Carolina Hydrogen and Fuel Cell Alliance, received $12.5 million from the U.S. Department of Energy for its Future Fuels Program.[123]
The 14 German stations are planned to reach 50 by 2015[124] through their public-private collaboration Now-GMBH.[125] Japan has a hydrogen highway, as part of the Japanese Hydrogen Fuel Cell Project.
Duration
• - Description: This video shows a hydrogen fuel cell vehicle that will be on the market in 2015. The senior engineer at Toyota Fuel Cell Group is interviewed, who gives a brief explanation of what a hydrogen fuel cell is and briefly describes the operation of a hydrogen vehicle and the difference between it and hybrid vehicles. It is emphasized that it is a clean technology. from the environmental point of view.
6th Virtual Fuel Cell Interactive Visualization..
• - Direct link.
• - Author: NASA Glenn Graphics and Visualization Lab.
• - Duration: 1:36 minutes.
• - Description: video made from a simulation program for a tubular configuration fuel cell. The simulation allows us to control the amount of impurities in the fuel, thus showing how a high amount of these directly affects the operation of the cell. You can also control the speed of the simulation and the output power of the stack.
7th Video Series: Introduction to the Fuel Cell..
• - Direct link.
• - Author: Polytechnic University of Valencia: María Desamparados Ribes Greus.
• - Duration:1:59:41 hours.
• - Description: in this series of videos there is a complete analysis of the operation of fuel cells. Practically all the topics presented in this report are covered from a scientific-technical point of view, the explanations are made in a clear and, to the extent that the specialization of the topic allows it, informative. This is a complete introductory guide, which is why the entire series has been included.
Main Aspect: the fundamental aspects and properties of fuel cells are presented; focuses on its role in the renewable energy environment. Several general aspects of fuel cells are discussed as an introduction: their electrochemistry, their basic structure, their main characteristics and their applications. The following videos will delve into the aforementioned topics.
Electrochemical Basis of Fuel Cells: they deal, in greater depth, with the electrochemical foundations of the operation of fuel cells and electric batteries and the bases for solving problems for the calculation of electrical potential.
Main Components of a Fuel Cell: This video shows the main components (in your opinion) of a fuel cell, the electrode and the electrolyte, and describes their functions. Finally, it talks about the other components found in these devices.
General criteria for the classification of fuel cells: This video has a different name in the playlist: "Power Plants". However, the name of the presentation is what has been put at the beginning. Fuel cells are classified by their operating temperature and then the types of electrolyte they can use are discussed.
Fuels: as its name indicates, this video presents the fuels most commonly used in fuel cells.
Proton exchange membrane fuel cells: the basic characteristics of PEMFCs, their components and their operation are explained.
Transport in PEMFC: the transport phenomena that take place inside a fuel cell are explained. The passage of the fuel through the anode (and the oxidizer through the cathode) where we have platinum particles (catalyst) and through the electrolyte is seen. Subsequently, the phenomena that take place in the polymeric membrane are described.
Fuel cell power plant: a brief review of the operation of an individual cell is given and then gives way to explaining what a stack is and its inclusion in a power plant.
Fuels. Hydrogen: describes the main characteristics of hydrogen as a fuel, highlighting those that make it environmentally attractive. It also points out the inconveniences associated with its extraction, transportation and danger of explosion.
Applications of fuel cells: as its name indicates, the video is about the different applications in which fuel cells are used. It starts by talking about the general features and then gives way to the fixed applications. Finally, we talk about portable applications.
Deviations from ideal Behavior: the phenomena that cause the reduction in efficiency that occurs in fuel cells in operation are explained, comparing their operation with the ideal. The expressions that allow describing and predicting its behavior are presented.
Overpotential: describes the different types of losses, activation, resistive and concentration, associated with the different regions of the fuel cell polarization curve.
Direct Methanol Fuel Cells: methanol fuel cells (DMFC) and ethanol fuel cells are presented. Its foundations and the advantages and limitations of its use compared to other fuel cells are discussed, mostly comparing it with PEM.
Alkaline Fuel Cell: describes the operation of the alkaline fuel cell. It talks about their advantages and disadvantages and compares them with other types of fuel cells. Its most common applications are also presented.
8º Compact, high-power hydrogen fuel cell for release in spring 2013.
• - Direct link.
• - Author: Digiinfo TV.
• - Duration: 2:46 minutes.
• - Description: the video shows us different types of fuel cells designed by Kyoto University applicable to both devices with low power requirements (mobile phones, laptops, etc.) and media (plasma televisions) and even with high powers that allow powering several devices simultaneously or generating electricity for a home.