CA Gas Utilities Produce Cutting Edge Clean Biogas

23 Jun 2020

SoCal Gas and Pacific Gas & Electric announced June 22 a significant breakthrough in a new electrochemical technology that converts carbon dioxide in raw biogas to renewable natural gas that can be put into pipelines.

It is a “critical improvement in the science of upgrading waste emissions to renewable gas,” according to the utilities. This technology also is commercially competitive.

The utilities collaborated with Opus 12, a clean-energy startup that began at Stanford University.

“Our vision for deploying this technology in California is to recycle CO2 emissions from industry and agriculture before they reach the air, and create valuable products such as renewable natural gas and feedstocks,” Etosha Cave, Opus 12 co-founder and chief science officer, said.

The raw gas used is from landfill waste, sewage and/or dairies. It is about 60% methane and 40% carbon dioxide.

Renewable gas supplies to date have been sourced from captured methane produced by dumps and dairies. Methane is a far more powerful greenhouse gas than CO2. To date, biogas upgrading technology has only removed the CO2.

“This cutting-edge method of using renewable electricity to convert carbon dioxide in biogas to renewable natural gas in a single-step process is significant to SoCalGas,” said Yuri Freedman, utility senior director of business development.

PG&E Manager of Innovation and Research and Development, Francois Rongere, added the emerging technology may help the company “find alternative sources of carbon-neutral fuel.”

The companies said that improved catalyst activity could speed reactions by up to five times, nearly doubling conversion efficiency. That makes the technology commercially competitive with other new biogas methods. The next step will be to test this technology for longer periods at an existing biogas facility.

The next day, microgrids fueled by renewable natural gas and standard gas were touted as being far less polluting than the diesel generators used for backup during power shutoffs and other outages. That is according to speakers at a webinar organized by the news site Microgrid Knowledge.

Earlier this month, state utility regulators approved PG&E’s plan to install diesel backup systems at its substations in high fire risk zones to keep power flowing to critical agencies and vulnerable customers. Many complained about the serious air quality and health impacts from the resulting toxic pollution from these microgrids.

Gas-fueled backup is not only relatively cleaner, it also can be more cost effective. They can fuel the distribution system and participate in the grid operator’s market, including supplying resource adequacy. These generators also can provide voltage and frequency control when disconnected from the main grid, speakers at a June 23 Microgrid Knowledge webcast said.

“The natural gas microgrid could nearly break even over its lifetime, in addition to providing highly valuable resilience to a local distribution substation,” according to a new report, Decarbonizing Resilience, Assessing Alternatives to Diesel Backup. It was written by the Brattle Group and released at the Tuesday webinar.

But so-called renewable gas, which can come from landfills or livestock operations, is more expensive than natural gas, thus microgrids fueled with it run less, generating less market revenue. At the same time, use of renewable gas slashes greenhouse gases.

In California and other states pushing to decarbonize their power sectors, fueling microgrids with renewable gas transported by pipelines, allows for a nearly decarbonized system.

“By burning the captured methane in a generator and converting it to CO2 as a result, GHG emissions can be reduced relative to the baseline scenario in which the gas is not captured or flared,” according to the Decarbonizing Resilience report.

Elizabeth McCarthy

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