Fuel hydrogen/methanol

Bipolar plates are integrating the functions of reactant distribution, current collection, and thermal management for each cell. For this purpose, the bipolar plates are containing distribution zones (flow fields) for fuel (hydrogen/methanol), oxidant (air) and coolant. The design of the flow fields must ensure spatially homogeneous reactant distribution across the active area as well as reliable and homogeneous removal of product water. 

Fuel cells can continuously convert the chemical energy of a fuel (hydrogen, methanol, methane, etc.) and an oxidant into electrical energy at up to 70% efficiency with very low pollutant emissions. Depending on the type of electrolyte used in a fuel cell, one can distinguish five main types ... 

Impermeability of fuels (hydrogen, methanol) and oxidants (air, oxygen)... 

The performance of a fuel cell is affected by many factors such as PEM conductivity, catalyst (Pt) loading level, membrane electrode assembly (MEA) fabrication techniques, fuel (hydrogen, methanol, etc.) and its feeding conditions (pressure, flow rate, humidification, etc.), oxygen/air feeding conditions (partial pressure, flow rate, humidification, etc.), and operation temperature. The fabrication techniques of MEA... 

Under the National Energy PoHcy Act of 1992 nonpetroleum-based transportation fuels are to be introduced in the United States. Such fuels include natural gas (see Gas, natural), Hquefied petroleum gas (qv) (LPG), methanol (qv), ethanol (qv), and hydrogen (qv), although hydrogen fuels are not expected to be a factor until after the year 2000 (see also Alcohol fuels Hydrogen energy). 

See also Efficiency of Energy Use, Economic Concerns and Engines Fuel Cells Fuel Cell Vehicles Hydrogen Methanol Synthetic Fuel. 

Ogden, J. Steinbugler, M. and Kreutz, T. (1999). A Comparison of Hydrogen, Methanol, and Gasoline as Fuels for Fuel Cell Vehicles. Journal of Power Sources 79 143-168. 

Until these materials have been developed, one attractive fuel is methanol, which is easy to handle and is rich in hydrogen atoms ... 

A major problem with the new sustainable energy sources is their reliability. Inherently they will produce electricity as the wind blows and the sun shines. The need for power is not constant either, with peak demands during the day. Hence, ways are needed to store energy that enable release on demand. Synthetic fuels and methanol are candidates, but the most important will be hydrogen. It can be produced conveniently from water and electricity with a reasonably high efficiency of 70 %. Hydrogen is the ideal fuel for fuel cells. 

Fuel cells are electrochemical devices transforming the heat of combustion of a fuel (hydrogen, natural gas, methanol, ethanol, hydrocarbons, etc.) directly into electricity. The fuel is electrochemically oxidized at the anode, whereas the oxidant (oxygen from the air) is reduced at the cathode. This process does not follow Carnot s theorem, so that higher energy efficiencies are expected up to 40-50% in electrical energy and 80-85% in total energy (heat production in addition to electricity). 

Thomas, C. et al., Fuel options for the fuel cell vehicle Hydrogen, methanol or gasoline, Int. J. Hydrogen Energ., 25, 551, 2000. 

Alternative fuel programs is the theme of Chapter three. Subjects include hydrogen, methanol, syn gas, biofuels, fueling methods, safety and storage. The chapter ends with a discussion of cost issues. 

Other hydride systems do not have such weight penalties and include magnesium nickel alloys, non-metallic polymers, or liquid hydride systems that use engine heat to disassociate fuels like methanol into a mixture of hydrogen and carbon monoxide. 

J. Yeom, G. Z. Mozsgai, B. R. Flachsbart, et al. Microfabrication and characterization of a silicon-based millimeter scale, PEM fuel cell operating with hydrogen, methanol, or formic acid. Sensors Actuators B 107 (2005) 882-891. 

From the operational point of view, the major challenge is to understand the versatile role of water for structure and processes in fuel cells. As the main product of the reaction, the presence of water is unavoidable in any type of fuel cell running on hydrogen, methanol, or other hydrocarbon-based fuels. In PEFCs in particular, water molecules determine the interactions between molecular... 

Figure 26. Schematic of a polymer electrolyte membrane (PEM) fuel cell. The fuel cell stacks operate at 30—180 °C with 30—60% efficiency. Fuel options include pure hydrogen, methanol, natural gas, and gasoline.

A direct-methanol fuel cell is very similar to the hydrogen fuel cells in this review, with the exception of the fuel. In a direct-methanol fuel cell, methanol is fed instead of hydrogen and reacts according to the reaction... 

Most fuel cells are powered by hydrogen, which can be fed to the fuel cell system directly or can be generated within the fuel cell system by reforming hydrogen-rich fuels such as methanol, ethanol, and hydrocarbon fuels. Direct methanol fuel cells (DMFCs), however, are powered by pure methanol. 

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