Fuel cells hydrogen

The Hydrogen Fuel cell is a developing technology that will allow great amounts of electrical power to be obtained using a source of hyrogen gas. 

Even in a simple hydrogen fuel cell system, capital cost reduction requires improvements in many diverse areas, such as catalyst loadings, air pressuriza-... 

Moore, R. M. Gottesfeld, S. and Zelenay, P. (1999). A Comparison Between Direct-Methanol and Direct Hydrogen Fuel Cell Vehicles. SAE Future Transportation Technologies Conference. Paper 99FTT-48 (August). 

While hydrogen engines have some advantages over natural-gas engines, the hydrogen fuel cell offers a true quantum leap in both emissions and efficiency. 

The rationale for using a hydrogen fuel cell is that the cell reaction produces only water. 

This automobile is powered by a hydrogen fuel cell with a proton exchange membrane. Its operation is pollution free, because the onl product of the combustion is water. 

In the United States so many vehicles operate on hydrogen fuel cells (sec Box 12.1) that hydrogen refueling stations have opened in many cities, including Washington, DC. 

Currently there is an urgent need to develop hydrogen storage materials for mobile and stationary appHcations. This trend is accelerated by the hydrogen fuel cell technology that could, within the next decades, replace fossil fuel resources such as oil and gas. 

Another important task will be to provide society with professional guidance and advice about the feasibility and merit of proposed technological solutions. It is our duty to point out when proposed processes create unrealistic expectations. An example of such guidance is the recent article by Shinnar [6] that motivated a discussion of the feasibility of use of hydrogen fuel cells in automobiles. 

The transient response of DMFC is inherently slower and consequently the performance is worse than that of the hydrogen fuel cell, since the electrochemical oxidation kinetics of methanol are inherently slower due to intermediates formed during methanol oxidation [3]. Since the methanol solution should penetrate a diffusion layer toward the anode catalyst layer for oxidation, it is inevitable for the DMFC to experience the hi mass transport resistance. The carbon dioxide produced as the result of the oxidation reaction of methanol could also partly block the narrow flow path to be more difScult for the methanol to diflhise toward the catalyst. All these resistances and limitations can alter the cell characteristics and the power output when the cell is operated under variable load conditions. Especially when the DMFC stack is considered, the fluid dynamics inside the fuel cell stack is more complicated and so the transient stack performance could be more dependent of the variable load conditions. 

The authors appreciate the support by research grants from the Korea Energy Management Corporation (KEMCO), SK Corporation, and National RD D Organization for Hydrogen Fuel Cell. 

Although the principle was first proposed in 1839, making a practical fuel cell eluded scientists for a centuiy and a half The concept is simple, but the chemistry is difficult. A hydrogen fuel cell must cleanly convert H2 into H3 O at one electrode and cleanly convert O2 into OH at the other electrode. In addition, the fuel cell must contain a medium that allows these ions to diffuse and combine stoichiometrically. 

In a hydrogen fuel cell, oxidation of H2 at the anode releases electrons into the circuit and produces aqueous H3 O ". Reduction of O2 at the cathode consumes electrons and generates OH , which combines with H3 O " to produce H2 O. The schematic diagram shows these processes. 

A hydrogen fuel cell is environmentally friendly, but H2 is much more difficult to store than liquid fuels. The production, distribution, and storage of hydrogen present major difficulties, so researchers are working on fuel cells that use liquid hydrocarbon fuels. One such fuel cell is composed of layers of yttria-stabilized zirconia (YSZ), which is solid Zr02 containing around 5% Y2 O3. This cell uses the combustion of a... 

Today s society asks for technology that has a minimum impact on the environment. Ideally, chemical processes should be clean in that harmful byproducts or waste are avoided. Moreover, the products, e.g. fuels, should not generate environmental problems when they are used. The hydrogen fuel cell (Chapter 8) and the hydrodesulfurization process (Chapter 9) are good examples of such technologies where catalysts play an essential role. However, harmful emissions cannot always be avoided, e.g. in power generation and automotive traffic, and here catalytic clean-up technology helps to abate environmental pollution. This is the subject of this chapter. 

Jacobson MZ, Colella WG, Golden DM. 2005. Cleaning the air and improving health with hydrogen fuel-cell vehicles. Science 308 1901-1905. 

Source Adapted from Hydrogen Fuel Cell Engines and Related Technologies, College of the Desert, Palm Desert, CA, 2001. 

Ahluwalia, R.K. and X. Wang, Direct hydrogen fuel cell systems for hybrid vehicles. /. Power Sources, 139(1-2), 152-164,2005. 

Hydrogen Fuel Cell, http //wwwl.eere.energy.gov/hydrogenandfuelcells/mypp/pdfs/ production.pdf, May 2000. 

Avchi, A., Onsan, I., and Trimm, Dv On-board fuel conversion for hydrogen fuel cells Comparison of different fuels by computer simulations, Appl. Catal. A General, 216, 243, 2001. 

Lehmann J., Luschtinetz T., Menzl F., The wind-hydrogen-fuel cell chain, Proceedings of the 14th World Hydrogen Energy Conference, Montreal, Canada, 2002. 

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