Making use of fuel cells to generate electricity is one way to create a renewable source of energy. At the end of the 20th century fuel cells were used for the first time to provide electricity and water aboard spacecraft. Now this technology has come down to earth! Fuel cells can be used to generate electricity to power vehicles, homes and industry.
As long as a renewable source of hydrogen is used to power the fuel cells it is considered a renewable form of energy. In California, fuel cell systems can qualify for funding under the state's Renewable Energy Buy-Down Program as long as a renewable source of hydrogen is used. Unlike fossil fuels the fuel of such cells is not burned. Instead it is combined in a chemical reaction.
Fuel cells are made up of two electrodes sandwiched around an electrolyte. When oxygen passes over one electrode and hydrogen over the other electricity, heat and water are produced. Hydrogen is fed into the fuel cell’s anode. Oxygen enters the cell via it’s cathode. A catalyst is used to cause the hydrogen atom to split into a proton and an electron. Each of these takes a different route to reach the cathode.
Fuel cells can obtain hydrogen from any hydrocarbon fuel. Some possibilities are natural gas, methanol, gasoline, propane, hydrogen, anaerobic digester gas from waste water treatment facilities, and landfill gas. Fuel cells may be used to power stationary electric power plants.
In this case they offer a source of electricity that is clean, reliable and of good quality. Smaller systems can act as a back up power source for hotels, hospitals, manufacturing facilities, and retail shopping centers. At some point smaller fuel cell systems will be sold for private use. Fuel cells might become more and more commonplace as a source of clean energy.
The good thing about fuel cells is that they can supply high quality consistent power. There are no disruptions or voltage distortions such as with conventional sources of electricity. Heat is also produced by fuel cells and this can be used as hot water, heating and cooling and many industrial functions.
There are several different types of fuel cells:
1) Proton Exchange Membrane (PEM) fuel cells – These were used in the "Gemini" space craft missions. A solid polymer ion exchange membrane acts as an electrolyte and Platinum Ruthenium is the catalyst in this type of fuel cell. These cells are under examination for use in buses and smaller vehicles.
2) Phosphoric Acid fuel cells – These fuel cells use platinum as a catalyst. The cells need aqueous phosphoric acid as an electrolyte.)
3) Alkaline fuel cells – These are an older type of fuel cell. They use platinum or palladium as the catalyst for a potassium hydroxide electrolyte.
4) Molten carbonate fuel cells – These cells use nickel-based catalysts and molten carbonates as electrolytes. They are able to function at higher temperatures. The fuel can be reformed into hydrogen inside cell. This kind of cell is used to power many larger fuel cell systems.
5) Solid oxide fuel cells use a coated zirconia ceramic as the electrolyte. This means the cells can function at very high temperatures. This type of cell does not need a catalyst. This is a newer fuel cell technology and may offer cheaper energy and greater quantities in the future.
