Power-to-X (PtX) refers to technologies that convert excess electricity from renewable energy sources into chemical energy carriers and raw materials. The key process here is electrolysis, in which water is split into hydrogen and oxygen using electricity. The green hydrogen produced in this way serves as the starting point for further conversion processes and thus acts as a link between the “world of electrons” and the “world of molecules.”
Historical Development
The concept emerged in the late 2000s under the term “power-to-gas.” In 2014, Professor Dr. Michael Sterner of OTH Regensburg coined the umbrella term “power-to-X” in a study for the think tank Agora Energiewende. Since then, it has gained widespread acceptance worldwide.
This development is part of a long tradition of hydrogen research that began as early as the 1980s with the founding of research institutes such as the Center for Solar Energy and Hydrogen Research in Stuttgart.
Technical Implementation
Hydrogen produced by electrolysis opens up various avenues for use. Three typical examples are:
- Direct use as pure hydrogen
- Combination with CO₂ to produce synthetic gas (SNG) or e-fuels
- Reaction with nitrogen to produce ammonia for the chemical industry
The Importance of Power-to-X for the Energy Transition
According to experts, 70 to 80 percent of global energy demand can be decarbonized through direct electrification. The remaining 20 to 30 percent—particularly in heavy industry and high-temperature applications—can only be made climate-neutral through hydrogen and power-to-X.
However, the rollout of these technologies faces several challenges:
- Electrolysers are relatively expensive and often cannot be mass-produced.
- The infrastructure for hydrogen transportation is still in its infancy.
- Many market participants consider the economic conditions and incentive programs to be insufficiently stable.
However, the rapid development of renewable energy—particularly photovoltaics—is creating favorable conditions for Power-to-X concepts in the future. As the cost of generating electricity declines, the conversion to molecular energy carriers is becoming increasingly attractive.
Here, Prof. Michael Sterner explains the concept in more detail.
Excess electricity (power) is converted into a variety of different energy carriers (X) via hydrogen as an intermediate step (© OTH Regensburg(
