What exactly is power-to-X?

Illustration of power-to-X processes, products and applications
Illustration of power-to-X processes, products and applications, © WZB

Efforts to transform the energy sector have so far focused on increasing renewable generation capacity to lay the foundation for a future energy system. This has made the use of electricity in the heat and transportation markets all the more important, since electric power is an efficient means of generating and using renewable sources of energy.

To offer transformative solutions to address their intermittency, renewed attention has to be given to storage technologies, grid flexibility and demand side management. Power-to-X, or P2X, provides multiple options to meet the challenges ahead.

Hydrogenics

Michael Sterner, a professor at OTH Regensburg University in Regensburg, Germany, defines power-to-X as “the means to convert electricity, understood to be primary energy, into an energy carrier, heat, cold, product, or raw material. It is an umbrella term for different ways of generating energy, namely power-to-gas, power-to-liquid, power-to-fuel, power-to-chemicals and power-to-heat.” His definition shows that the X in P2X stands for a variety of products, processes, technologies and applications (see fig. 1).

Some, specifically power-to-heat and power-to-mobility, use electrical energy as a direct power source. Others, namely power-to-gas, power-to-liquid, power-to-fuel and power-to-chemicals, produce substances or materials for certain sectors of the economy. A third group of methods stores electric power in hydrogen and methane to meet demand from the public grid at some future time. Thus, P2X provides the opportunity to create long-term storage options and substitute hydrogen, methane and other synthetic fuels for fossil energy sources in transportation, chemical processing and heat production.

The relatively low efficiency of power-to-X methods producing synthetic fuels limits their employment to areas in which the direct use of renewable sources of energy is either barely possible or simply not possible at all. For example, the high energy density required in the maritime and aviation industries makes electrification difficult to achieve, whereas chemical plants use hydrogen as a base component to manufacture several kinds of goods, such as adhesives and fertilizers.

read more in H2-international April 2019

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