As nations install more and more renewable energy sources in pursuit of the “green revolution”, so the need increases for other sources which will ensure a steady supply of energy when the sun is not shining or the wind is not blowing. At present such backup power is commonly supplied by gas turbine generators powered by natural gas, which are quick-starting and thus more flexible than traditional coal-fired power stations. While natural gas is a fossil fuel, it burns much cleaner than coal and oil, emitting 50-60% less CO2 when used for power generation, and for this reason it is regarded as a “transition fuel”, providing backup and grid stabilisation until such a time as “greener” alternatives are available.