Power to gas is a concept that concerns the conversion of surplus electricity, either from renewable or conventional sources, to chemical energy. There are two major processes in power to gas: the electrolysis process and the methanation process. From this, there are three types of electrolysis process, namely, alkaline, proton exchange membrane (PEM) and solid-oxide electrolysis. And, there are two types of methanation process: thermocatalytic and biological methanation.
The hopes for power to gas technology are immensely high, as it may provide a clean method to store excess generated electricity, stabilise the power grid or redirect excess electricity toward other useful applications. With serious research and development (R&D) efforts all over the world, the technology readiness level (TRL) of power to gas is expected to rapidly increase, thus, establishing a complete system in the near future.
The main purposes of the conversion, from electricity to gas, are to store excess generated electricity, stabilise the power grid, or redirect excess electricity toward other useful applications.
The two major processes in power to gas conversion are the electrolysis process and the methanation process. The electrolysis process is to convert electricity to hydrogen, while the methanation process is a method to produce synthetic methane (by combining hydrogen generated from the electrolysis process with carbon dioxide).
There are three types of electrolysis process, namely, alkaline, proton exchange membrane (PEM) and solid-oxide electrolysis. Alkaline and PEM electrolysis processes are already commercialised, but the solid-oxide process is still in the R&D phase. R&D trends for electrolysis is shifting towards building a high performance and low cost process by creating advanced electrocatalysts and thermally stable materials at high temperatures.
The methanation process consists of, mainly, two types: thermocatalytic and biological methanation. Thermocatalytic methanation is already commercialised while biological methanation is still in the pilot stage. The major R&D theme for the methanation process is to develop a high performance catalyst.
Hydrogen or methane produced from the electrolysis or methanation process in power to gas systems can be converted back to usable power by stationary fuel cells, internal combustion engines or a combined heat power (CHP) system.
Adapted from press release by Francesca Brindle
Read the article online at: https://www.hydrocarbonengineering.com/gas-processing/01042016/surplus-electricity-converted-to-usable-hydrogen-methane-gas-2916/