James Cropper - Fuel Cells

Although fuel cell technology has enormous and exciting implications for the generation of energy in the future it is not a "new" technology. In fact it was developed in the middle of the nineteenth century by William Grove. Fuel cells work by "reverse electrolysis". Electrolysis is the process by which water can be split into its constituent elements, hydrogen and oxygen by the application of an electric current.

A fuel cell is a catalytic device that uses hydrogen and oxygen to produce a direct electric current by means of an electro-chemical reaction. Hydrogen molecules are ionised at the anode. The resultant "freed" electrons pass through a circuit to the cathode creating the current. The positively charged hydrogen ion passes through an electrolyte medium to the cathode. The electro chemical reaction produces heat. At the cathode the hydrogen combines with oxygen from air to produce water in vapour form as the exhaust. Fuel cells contain no moving parts and there is no combustion. Hence the resultant exhaust is very clean and noise levels low.

Hydrogen is the most common element on our planet. Hydrogen can be produced from water using renewable solar, wind, hydro or geothermal energy. Hydrogen is also found in hydrocarbon substances such as petroleum, natural gas, methanol, methane and coal gas. To extract hydrogen from the hydrocarbon requires a reforming process. The reforming process does generate emissions but to a much lesser extent than combusting fossil fuels.

For practical applications fuel cells are arranged in "stacks" to produce the necessary voltage. This will vary depending on the application, which will range from small portable units to houses, larger buildings, utilities, automobiles and locomotives. In addition to producing electricity, fuel cell stacks will be able to provide buildings with their heating and water needs. The power generating capacity of stationary sources can be readily increased by adding further stacks. Fuel cells require a continuous supply of hydrogen to operate. This necessitates infra-structure which will not only vary from application to application but may also be dependent on geography. Clearly mobile units will require an on-board supply whilst static applications can be fed from a grid network or stand alone source. The latter could be a finite/replaceable or renewable source.