Power-to-X

The X in the terminology can refer to one of the following: power-to-ammonia, power-to-chemicals, power-to-fuel,[3] power-to-gas (power-to-hydrogen, power-to-methane) power-to-liquid (synthetic fuel), power to food,[4] power-to-heat.

Collectively power-to-X schemes which use surplus power fall under the heading of flexibility measures and are particularly useful in energy systems with high shares of renewable generation and/or with strong decarbonization targets.

Reconversion technologies include gas turbines, combined cycle plants, reciprocating engines and fuel cells.

[1] However, while round-trip conversion efficiency of power-to-power is lower than with batteries and electrolysis can be expensive, storage of the fuels themselves is quite inexpensive.

[citation needed] This means that large amounts of energy can be stored for long periods of time with power-to-power, which is ideal for seasonal storage.

Despite it also being based fundamentally on electrolytic chemical reactions, battery storage is not normally considered a power-to-fuel concept.

The purpose of power-to-heat systems is to utilize excess electricity generated by renewable energy sources which would otherwise be wasted.

[1] Large-scale heat pumps in district heating systems with thermal energy storage are an especially attractive option for power-to-heat: they offer exceptionally high efficiency for balancing excess wind and solar power, and they can be profitable investments.