Power-to-X (also referred to as P2X and P2Y) is a number of electricity conversion, energy storage, and reconversion pathways that use surplus electric power, typically during periods where fluctuating renewable energy generation exceeds load. Power-to-X conversion technologies allow for the decoupling of power from the electricity sector for use in other sectors (such as transport or chemicals), possibly using power that has been provided by additional investments in generation. The term is widely used in Germany and may have originated there.

The X in the terminology can refer to one of the following: power-to-hydrogen, power-to-compressed air, power-to-ammonia, power-to-chemicals, power-to-fuel, power-to-gas, power-to-liquid, power-to-methane, power to food, power-to-power, and power-to-syngas. Electric vehicle charging, space heating and cooling, and water heating can be shifted in time to match generation, forms of demand response that some term power-to-mobility and power-to-heat.

Collectively power-to-X strategies 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. A large number of pathways and technologies are encompassed by the term.

In 2016 the German government funded a €30 million first-phase research project into power-to-X options. Since then, many large scale P2X projects have come online proving the strategy while more have entered into development. As a result, many other nations have embraced the model in their effort to participate in the emerging hydrogen economy.