3208 



Chapter 26 



Fuel cells can produce electricity at 38 to 40 percent efficiency, a rate about 

 equal to the best combustion power plant. It is expected that by 1985 fuel cell 

 efficiency may be 50 to 55 percent. Fuel cell emissions are well within environ- 

 mental limits (Energy Research and Development Administration 1976.) 



ELECTRON FLOW 



2H. 



> 



(FROM 

 HYDROGEN- 

 RICH FUEL) 



(-) 



(-I-) 



20 



<C 



(FROM AIR) 



ZHgO (WATER) 



Figure 26-28. — The basic principles of fuel cell operation (Energy Research and Devel- 

 opment Administration 1976). The fuel cell consists of an anode, cathode, and elec- 

 trolyte, much as in a battery. Hydrogen rich fuel is fed down the anode side of the cell. 

 Here the hydrogen leaves its electrons giving the anode a negative charge. Air enters 

 the fuel cell on the cathode side. Here oxygen accepts electrons from the cell giving 

 the cathode a positive charge. Electrical power is generated by the flow of electrons 

 from the anode to the cathode. Hydrogen ions formed at the anode and oxygen ions 

 formed at the cathode migrate through the electrolyte to combine and form water. 

 Heat is also liberated in the process. The overall simplified process is shown in 

 equation 26-12. (Drawing from Department of Energy.) 



