Power-to-Gas. Technologies, Challenges and Outlook

Power-to-Gas is the process by which electrical energy is converted into chemical energy in gaseous form. Compared with electricity, the gas produced in this way has the advantage of being easily storable in large quantities over the long term. Power-to-Gas also makes it possible to decarbonize industrial hydrogen, produce low-carbon gas and create synergies between electricity and gas networks.

Power-to-Gas relies primarily on electrolysis to produce hydrogen (Power-to-H ₂ ) from electricity and water. Alkaline, proton exchange membrane (PEM) and high-temperature electrolyzers (SOEC) are described in this article, along with other emerging technologies. Electrolysis can be complemented by a methanation step, allowing hydrogen to react with carbon dioxide to produce methane (Power-to-CH ₄ ). Catalytic and biogenic methane generators are described in this article, as well as the capture and supply of CO ₂ . The following ancillary units are also presented: electrical installations, water treatment, product gas treatment, compression, storage and transport via networks.

This article also presents the challenges and prospects of Power-to-Gas in terms of technology performance (energy yields, flexibility and response time), economic balance (costs of installations and of the megawatt-hour produced, in the form of H ₂ or CH ₄ ), environmental impact (greenhouse gas emissions), reliability and durability (control of failures and degradation) and safety (control of hazardous phenomena).

This article presents the initial R&D results and feedback from Jupiter 1000, France's first megawatt-scale industrial Power-to-Gas demonstrator, using two electrolysis technologies and one methanation technology.