fuel cells

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What are Fuel Cells?

Fuel cells are an electrochemical energy conversion device. Fuel cells are similar to batteries except that the chemicals they require can be replenished. In effect, fuel cells do not have a finite life (like batteries) and will continue to produce energy unless the device breaks down or the chemicals required are no longer available

How Fuel Cells Work
The most promising model of fuel cell technology is called the proton exchange membrane fuel cell (PEMFC) which uses hydrogen and oxygen to produce electrical energy and water. It has four main parts: an anode (a negatively charged material through which hydrogen gas is pumped); a cathode (a positively-charged material through which oxygen gas is pushed); a catalyst (situated between the cathode and anode and facilitates the reaction of oxygen and hydrogen); and the proton exchange member (conducts positively charged ions and blocks negatively charged ions).
Pressurized hydrogen (H2) enters the fuel cell through the anode side and is pushed through the catalyst which forms two positively charged hydrogen ions (H+) and two negatively charged electrons. The anode 'transfers' the electrons through an external circuit (this forms an electrical charge) which then transfers it back to the cathode side, where they interact with negatively-charged oxygen atoms.

The oxygen atoms are formed when oxygen gas (O2) is pushed through the cathode and catalyst, where they are 'split' to form two negatively-charged oxygen atoms. They will attract two positively charged hydrogen ions (H2) and they will combine to form water (H2O).

The reaction in a single fuel cell produces around 0.7 volts of electricity. A combination of PEMFCs (called a fuel-cell stack) combines the output of several PEMFCs to produce useful electricity.