PtG

PtG, or Power-to-Gas, is a set of technologies that convert surplus electrical energy into chemically stored energy in gaseous form, primarily hydrogen or methane. It aims to enable long-duration energy storage, seasonal shifts, and cross-sector coupling by linking the electricity system with gas networks and other energy uses.

The basic concept involves two stages. First, electricity powers water electrolysis to produce hydrogen (PtH). Second, the hydrogen can be used directly, or converted with carbon dioxide in a methanation process to form methane or other synthetic gases. Methanation typically uses the Sabatier reaction to produce methane suitable for injection into natural gas grids or for use as a transport fuel. PtG can therefore provide either hydrogen or a synthetic natural gas substitute, expanding options for storing renewable energy.

Key components include electrolysers (such as PEM, alkaline, or solid oxide types), units to supply and capture CO2, methanation reactors, gas purification and compression hardware, and storage or injection systems for the produced gas. The produced gas can be stored long term underground, in tanks, or injected into existing gas infrastructure, enabling flexible use in heating, electricity generation, or transport.

Benefits of PtG include enhanced grid stability, long-term energy storage, and better utilization of renewable energy. It also supports sector coupling by providing a versatile energy carrier. Challenges involve energy losses during conversion, capital costs, CO2 sourcing and purity, gas quality standards, and safety/regulatory considerations. PtG projects are at pilot and demonstration stages in several regions, with policy support seen as crucial for large-scale deployment.