Southern California Gas Co. has partnered with a German company to research the commercial viability of technology capable of converting renewable electricity into pipeline quality natural gas.

The company has joined Electrochaea, which has patented the technology, to commission the nation’s first scalable biomethanation reactor system at the U.S. Department of Energy’s National Renewable Energy Laboratory facility in Golden, CO. The project, SoCalGas said, would assess the technology’s potential for MW-scale system designs.

The process builds on power-to-gas technology, which has increasingly gained traction as a way to help decarbonize the energy sector along with batteries, advanced nuclear power and other emerging technologies. It’s also viewed as a way to capture the excess renewable energy in places like in California that is generated in abundance when demand is lower.

“In order to achieve our climate goals, we need to find solutions to the difficult problem faced with renewables like wind and solar -- the issue of intermittency, and extensive mismatches between the periods of renewable energy generation and consumer demand,” said SoCalGas’s Yuri Freedman, who oversees business development. “This project shows our existing natural gas pipeline infrastructure can store excess renewable energy for periods of time ranging from seconds to months.”

In California, where carbon-free power sources account for more than half of the state’s total electricity mix, natural gas has increasingly found a secondary role to backup variable output renewables. 

Power-to-gas uses renewable energy to convert water into hydrogen through the process of electrolysis. The hydrogen can then be mixed into the natural gas stream and stored in pipelines for later use. The biomethanation reactor system researched in Colorado adds another step after the electrolysis process. The hydrogen is combined with carbon dioxide and fed into the reactor where single-celled microorganisms ingest the hydrogen and carbon dioxide and emit methane to produce renewable natural gas (RNG) that can be used downstream.

The system is also capable of recycling carbon dioxide, which would prevent greenhouse gas emissions and help reduce the consumption of fossil methane if proved on a commercial scale. The methanation system was designed by Electrochea and demonstrated in Europe.

SoCalGas said the research project would focus on improving the technology’s efficiency, automating plant operations, reducing capital costs and identifying locations in the West, including California, where grid-scale storage would be most beneficial and cost-effective.

California is among the largest of the energy consumers in the country. However, SoCalGas noted that over the next decade the state is expected to waste enough renewable energy each year to power Los Angeles County, the nation’s most populous.  The company is also grappling with California’s aggressive policies to decarbonize the economy, curb emissions and generate more energy with renewable sources.

SoCalGas, which has more than 21 million customers in Central and Southern California, aims to replace 20% of its natural gas supply with RNG, typically produced by dairy farms, landfills and wastewater treatment plants, by 2030.