The hydrogen economy.

Being able to store surplus energy would reduce the problems of relying on intermittent energy resources. Hydrogen can be produced by using surplus electricity to electrolyse water.

There are several ways to store hydrogen:

• As compressed gas, but energy must be used to run the compressor.
• Liquefied under high pressure at very low temperature, but energy is used to run the compressor and refrigeration system.
• Metal hydrides allows the storage of gas at low pressure as the hydrogen absorbs onto the surface of the metal matrix. The storage tanks are larger and heavier than a petrol tank that stores the…