Hydrogen-PEM fuel cell

Cost component distribution for a direct hydrogen PEM fuel cell system. (From B. D. James and J. A. KaHnoski. Annual progress report, DOE Hydrogen Program, 700-704. Washingtoiv D.C. U.S. Department of Energy, 2007.)... 

PV via electrolysis. In Canada, the National Research Council in Vancouver is also demonstrating the combination of hydrogen PEM fuel cells with photovoltaic and electrolyser powering systems as a back up power for buildings. 

The electro-catalytic oxidation of hydrogen, and reduction of oxygen, at carbon supported platinum based catalysts remain essential surface processes on which the hydrogen PEM fuel cell relies. The particle size (surface structure) and promoting component (as adsorbate or alloy phases) influence the activity and tolerance of the catalyst. The surface chemical behavior of platinum for hydrogen, oxygen, and CO adsorption is considered, in particular with respect to the influence of metal adsorbate and alloy components on close packed and stepped (defect) platinum surfaces. Dynamical measurements (employing supersonic molecular beams) of the... 

Develop realistic and internally consistent detailed designs for automotive gasoline fuel processors and direct hydrogen PEM fuel cell systems based on current-year technology. 

A direct methanol fuel cell has been developed that is similar to the hydrogen-PEM fuel cell. The reactions in the cell are... 

Borup RL, Inbody MA, Wood DL, Pacheco SD, Guidry DR, Xie J, Tafoya JI, Blom D (2003) Fuel cell reformer and stack durability gasoline reformate hydrogen - PEM fuel cell durability, Fuel Cell Seminar, Nov 2003, Miami... 

Fuel cells are often named for either the fuel or the electrolyte used. In the hydrogen-PEM fuel cell (the acronym PEM stands for either proton-exchange membrane or polymer-electrolyte membrane), the anode and cathode are separated by a membrane that is permeable to protons but not to electrons (T Figure 20.24). The membrane therefore acts as the salt bridge. The electrodes are typically made from graphite. 

The hydrogen-PEM cell operates at around 80 °C. At this temperature the electrochemical reactions would normally occur very slowly, and so small islands of platinum are deposited on each electrode to catalyze the reactions. The high cost and relative scarcity of platinum is one factor that limits wider use of hydrogen-PEM fuel cells. 

A Figure 20.24 A hydrogen-PEM fuel cell. The proton-exchange membrane (PEM) allows generated by H2 oxidation at the anode to migrate to the cathode, where EI2O is formed. 

Figure 15.27 Polarization characteristics of pure hydrogen PEM fuel cell compressor at 60 °C. Reprinted with permission from Onda et al. (2007).

Figure 15.28 Polarization characteristics of hydrogen PEM fuel cell separator with a H2—N2 anode feed.

Hydrogen PEM Fuel Cells A Market Need Provides Research Opportunities... 

It has been said that necessity is the mother of invention. Another way this can be stated is market demands create research opportunities. Because of a globally increasing demand for oil, which is a depleting (not renewable) energy source, the market also demands alternate sources of energy that are competitive in cost and use. This market demand offers opportunities for investment in hydrogen PEM fuel cell research. 

The cost of an 80-kW hydrogen PEM fuel cell has been reduced substantially over the past several years. Figure 2 below depicts the projected reduction in total system cost. (These projected costs are based upon the manufacture of 500,000 units per year.)... 

Carbon monoxide is one of the most common impurities in hydrogen fuel streams that can cause significant performance degradation of a hydrogen PEM fuel cell. When carbon-based feedstock is used for the production of hydrogen, the CO impurity in the hydrogen stream is unavoidable. To illustrate this fact. Table 9.8 lists the compositions of hydrogen feed streams produced from carbon-based feedstocks [42]. 

The catalyst loading tends to be as much as ten times higher than with hydrogen PEM fuel cells, 2 mg cm or more (Havranek et al., 2001 and Dohle et al., 2002), compared to 0.2 mg cmfor standard hydrogen PEMFCs. There are three main reasons for this ... 

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