Fuel Cells

19 Pages 4739 Words

Fuel Cell Background Information

1. INTRODUCTION
Petroleum, the worlds most prolific fuel, is becoming more scarce and its burning produces emissions which shoulder much of the responsibility for air pollution (Fig. 1). Contributions also come from deforestation, carbon dioxide from the burning of coal, and methane release. In order to reverse the trend of destroying the environment, a change to a more ecologically mundane resource, or method of producing energy such as hydrodynamic, wind, geothermal, solar and tidal is desirable. These methods are presently employed in a somewhat small scale, but require specific environments in order to work effectively. Fuel cells need no particular environment to work well (other than a heat sink) and is highly efficient both electrically and physically (without sound and with far fewer harmful air pollutants).
A fuel cell is an electrochemical device which brings together hydrogen and oxygen, or air in the midst of a catalyst to produce electricity, heat and water. (Fig. 2) or (Fig. 2a) The single cell fixture consists a single electrolyte sandwiched between electrodes. This inner sandwich is then placed in-between current collectors which usually serve as the poles of the cell. A fuel cell generates current by transforming (usually by using the catalyst in the electrodes) hydrogen gas into a mixture of hydrogen ions and electrons on the anode side of the cell. Because of the insulating nature of the electrolyte, the anions transfer through the electrolyte to the cathode side of the cell while the electrons are conducted to the current collectors and through a load to do work. The electrons then travel to the cathode side current collector where they disperse onto the electrodes to combine with incoming hydrogen anions, oxygen, or air in the presence of a catalyst to form water completing the circuit.
This process occurs in all types of fuel cells (alkaline, solid polymer, phosphoric acid ...