Southern California Gas Co (SoCalGas), Pacific Gas and Electric Company (PG&E) and Opus 12, a clean energy start-up, have developed new electrochemical technology that converts the carbon dioxide (CO2) content in raw biogas into pipeline-quality renewable natural gas (RNG).
The single-step process was designed to use renewable electricity and therefore also provides a way for the long-term storage of excess wind and solar power. The 12-month research and development effort was funded by SoCalGas and PG&E and builds on the success of an initial feasibility study in 2018.
Raw biogas produced using anaerobic digestion contains roughly 60% methane, the main component of natural gas, and 40% CO2. While current biogas upgrading technology removes the CO2 from biogas, this new technology captures the CO2 and converts it into additional renewable fuel.
The new demonstration shows that improved catalyst activity could speed reactions by five times and nearly double conversion efficiency, making the technology commercially competitive with other new biogas upgrading methods, according to the companies. The core technology was scaled up and tested using commercially available electrolyser hardware. The next step will be to test the technology for longer periods at an existing biogas facility.
Yuri Freedman, SoCalGas’ senior director of business development, said: “This cutting-edge method of using renewable electricity to convert CO2 in biogas to RNG in a single-step process is significant to SoCalGas.
“As we work to meet California’s ambitious climate goals, emissions-reducing innovations like these will help us protect the environment by providing a reliable carbon-neutral fuel.”
“PG&E is deeply committed to meeting California’s bold vision for a sustainable energy future in a reliable and cost-effective manner for customers,” added PG&E’s manager of innovation and research and development, Francois Rongere.
“We continue to work toward advancing innovation that provides new possibilities in our quest to reduce greenhouse gas emissions and find alternative sources of carbon-neutral fuel. We are very proud to be part of this collaboration with Opus 12 and SoCalGas.”
Dr Etosha Cave, Opus 12 co-founder and chief science officer, commented: “We achieved significant advances in reaction rate and demonstrated the scalability of our approach by moving from lab scale to commercial-grade components. We look forward to continuing to work with our partners at SoCalGas and PG&E toward a field demonstration of this technology.”