Fuel Cells are a little-known technology that date from 1838. The basic principle is that they reverse electrolysis of water. In electrolysis, we place electrodes in water and when we apply a voltage the water starts splitting and we collect different gases at each electrode. Bubbles of oxygen at the anode and bubbles of hydrogen at the cathode. We can recombine oxygen and hydrogen explosively with a flame (see video below) or we can recombine them slowly and produce a flow of electricity. So a fuel cell allows us to produce electricity from stored hydrogen (and oxygen from the air). This means we don’t need a battery if we have a tank of hydrogen. Of course the tank of hydrogen would need to be made through electrolysis some time earlier!

We can use renewable electricity to produce hydrogen during times of high wind or bright sunlight and we will have only to store hydrogen as an energy carrier for later use in a fuel cell.

Fuel cells can be found in a few Fuel Cell Electric Vehicles today but they are not as popular as battery electric cars because they are more expensive and there are very few hydrogen filling stations. Also the hydrogen fuel is more easily made from natural gas (a fossil fuel) at present and that means the carbon footprint of fuel cell vehicles is still quite high. An area of active research and development is fuel cells for industry. Eventually they will help decarbonise (remove carbon from) industry when they use hydrogen from electrolysis.

Did you know that fuel cells were used on the NASA Apollo missions to the Moon some 50 years ago? The oxygen tanks that exploded in Apollo 13 were to power the spacecraft’s fuel cells!

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