Definition: Power to gas systems, or P2G for short, makes use of surplus electricity produced by wind farms rather than let it go to waste otherwise. The surplus electricity goes back into the electric grid and to the power station, where it is converted to gas instead of electricity. To do this, the surplus electricity is passed through water where it is split into oxygen and hydrogen. The hydrogen is combined with carbon dioxide to make methane gas, which can be used for cooking and heating.