Power-to-X is an umbrella term for technologies capable of utilising or storing a future oversupply of electricity from renewables such as wind and solar energy or hydropower. This is a way to turn fluctuating generation from renewables into controllable energy. Depending on the application in each case, a distinction can be made between Power-to-X, Power-to-Gas, Power-to-Liquid and Power-to-Heat.
The Power-to-Gas process (PtG, P-t-G or P2G) uses water electrolysis to produce a gas using surplus electricity and CO2, as appropriate. This gas (e.g. hydrogen or methane) can either be stored or used as a chemical raw material. Stored gas can be reconverted into electricity in gas-fired power stations later when the infeed of renewables is insufficient. The gas network is an ideal candidate for storage purposes. However, the gas can also be converted into liquid energy sources. In this case we refer to Power-to-Liquid.
The Power-to-Liquid process (PtL, P-t-L or P2L) aims to produce fuels in liquid form. Compared to the gas that is produced, fuels in liquid form are easier to store. The use of P-t-L fuels makes particular sense in situations where direct electrification with renewable electricity would be difficult to achieve. Examples are heavy goods traffic (rail, goods vehicles, ships) and air transport.