In partnership with the US Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy’s (EERE) Bioenergy Technologies and Fuel Cell Technologies Offices (BETO), National Renewable Energy Laboratory (NREL) and utility Southern California Gas Co. (SoCalGas) are running a new pilot-scale bioreactor that uses a microorganism to biologically convert hydrogen (H2), produced via electrolysis, and carbon dioxide (CO2) into biomethane.
According to a statement, this “Power-to-Gas” (PtG) technology can be used to upgrade biogas to “pipeline quality” natural gas – called biomethane or renewable natural gas (RNG) – and distributed to users through existing natural gas distribution pipelines.
The microorganism, Methanothermobacter thermautotrophicus, was discovered in a hot spring in Iceland and was modified to become more efficient at producing methane from carbon dioxide. NREL’s goal is to improve the economics of methane production by increasing the pressure in the bioconversion reactor.
The process is a way to recycle carbon dioxide in biomethane and to store the energy in low-cost renewable electricity as biomethane in the natural gas grid. This approach can also be a key stepping stone to synthetic liquid fuels in the future.