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US DOE and SoCalGas fund microbial Power-to-Gas project

In the United States (US), Southern California Gas Co. (SoCalGas) has announced that grant funding has been awarded to Lawrence Livermore National Laboratory (LLNL) and Stanford School of Engineering's Spormann Laboratory to conduct new power-to-gas research using microbes. The two entities will receive US$800 000 from the US Department of Energy (DOE) and SoCalGas will provide co-funding of US$400 000 in addition to US$125 000 of seed funding that was provided in 2017.

US-based clean-tech startup Opus 12 has demonstrated carbon dioxide (CO₂) conversion to 16 different products with its modular and scalable electrochemical technology including power-to-gas with SoCalGas (photo courtesy Opus12).

According to Los Angeles headed Southern California Gas Co. (SoCalGas), a subsidiary of San Diego headed holding company Sempra Energy, Lawrence Livermore National Labs (LLNL) and Stanford School of Engineering’s Spormann Laboratory will study new technology with the potential to significantly reduce the cost of producing renewable natural gas (RNG) and reduce carbon dioxide (CO2) emissions.

In a statement August 1, SolGasCo said that the initiative will “research the use of microbes” to convert CO2 directly to methane (CH4) using renewable electricity, a process known as microbial electromethanogenesis (ME). If developed as envisioned, ME could become a highly efficient, large-scale storage technology for excess wind and solar energy.  This would, in turn, make both renewable electricity and RNG less expensive and more plentiful.

The research will continue past research by Spormann Laboratory on microbes that create CH4, as well as advances in 3D-printed carbon aerogel electrode materials made by LLNL, which will be assessed for their viability in reactors. Biogas will be supplied by Delta Diablo, a Livermore, California, wastewater treatment plant (WWTP). Raw biogas is mostly methane, but also contains about 30 to 40 percent CO2, which is typically vented to the atmosphere in a biogas production facility.

This technology has the potential to cut the cost of processing biogas, while nearly doubling the amount of this easily-stored renewable energy and reducing carbon dioxide emissions. It could make a big difference for small-scale biogas producers like dairy farms and feedlots, which collectively make up the majority of California’s renewable natural gas potential, said Yuri Freedman, Senior Director of Business Development at SoCalGas.

Power-to-gas offers storage advantages

SoCalGas provided funding to this research to further develop power-to-gas (P2G) technologies, which stores excess renewable electricity as a renewable gas rather than in conventional batteries. Power-to-gas has two distinct advantages over batteries: nearly unlimited amounts of electricity can be easily stored for very long periods of time, and it can be stored and used with existing infrastructure.

Through this project, we intend to devise scalable, efficient prototype reactors that enable both economical upgrading of biogas and storage of renewable electricity as methane. To do this, we will leverage recent advances in materials synthesis and manufacturing to fabricate reactors tailored to the requirements of the microbes and the overall process, said LLNL chemist Sarah Baker.

Between 3.3 and 7.8 TWh of excess solar and wind energy will be curtailed in California by 2025 due to time-of-day supply/demand mismatches, according to a recent Lawrence Berkley National Lab study. If that excess solar and wind energy were converted to methane and stored as RNG, 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.

Capturing methane and carbon dioxide from farms, wastewater treatment plants and landfills and then delivering it through existing pipelines is a cost-effective option to reduce greenhouse gas (GHG) emissions. A recent analysis found that California could achieve the same GHG as electrifying buildings at a much lower cost by replacing just a fraction of the natural gas delivered through its pipelines with RNG.

Consumers prefer gas over electricity

The University of California at Davis estimates that the natural gas needs of around 2.4 million California homes could be fueled with RNG derived from the state’s existing organic waste.  Already, 60 percent of the fuel used in natural gas vehicles in California is renewable, and SoCalGas expects that to increase to 90 percent by 2019.

Technological advances like P2G and RNG can reduce GHG emissions while providing energy resiliency and meeting consumers’ fuel preferences. According to SoCalGas, people across Southern California prefer natural gas four to one over electricity because it is more affordable and reliable, and more than 90 percent of residents use natural gas in their homes.

The research will be conducted at both LLNL and Stanford School of Engineering beginning in August and is expected to be complete by mid-2020.

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