SoCalGas and NREL Install Nation's First Biomethanation Reactor System

Southern California Gas Co. (SoCalGas) announced the successful installation of a novel bioreactor system that will be used to test power-to-gas technology at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) in Golden, Colorado. Power-to-gas technology is a cutting-edge method of storing excess renewable energy. The project is the first of its kind in the United States converting hydrogen generated from excess renewable power into pipeline quality methane for use in homes, businesses and in transportation.

“Power-to-gas technology can significantly increase the overall amount of renewable energy we use, by providing an economical method of storing excess solar-and wind-generated electricity,” said Jeff Reed, director of business strategy and advanced technology at SoCalGas. “And this technology takes advantage of existing infrastructure, and can hold excess renewables for days, weeks or months to shift solar from day to night, address weather patterns and even seasonal patterns.”

According to a 2017 Lawrence Berkley National Lab study, by 2025, between 3,300 and 7,800 gigawatt-hours of excess solar and wind energy will be curtailed in California. If all that excess solar and wind energy were converted to methane through the biomethanation process and stored as renewable natural gas, it would provide enough renewable energy to heat 158,000 to 370,000 homes or provide renewable electricity to 80,000 to 187,000 homes.

Power-to-gas technology uses renewable electricity when prices are low—including times when renewable supply exceeds demand and would otherwise be wasted—to power an electrolyzer, which splits water to produce hydrogen. The hydrogen is then combined with carbon dioxide and fed to a biomethanation reactor where it is converted into RNG by special micro-organisms. RNG can be used in any application currently served by natural gas, from home appliances to natural gas-powered vehicles.

The research will also test how effectively the microbes convert hydrogen to methane and how efficiently the storable methane can be converted back to electricity. Tests will also examine the potential of power-to-gas technology to store large quantities of renewable energy for up to an entire year and how it compares in performance and cost to battery storage. Initial reports are expected beginning in 2018. The study will continue for several years.