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DOE and SoCalGas funding LLNL and Stanford in new power-to-gas research: microbial electromethanogenesis

The US Department of Energy (DOE) and Southern California Gas Co. (SoCalGas) have awarded funding to Lawrence Livermore National Laboratory (LLNL) and Stanford School of Engineering’s Spormann Laboratory to conduct new power-to-gas research. LLNL and Stanford will receive $800,000 from the US Department of Energy (DOE). SoCalGas will provide co-funding of $400,000 in addition to $125,000 of seed funding it provided in 2017.

The initiative will research the use of microbes to convert CO2 directly to methane using renewable electricity, a process known as microbial electromethanogenesis (ME). Methanogens are single-celled organisms that use electrons to convert CO2 into methane. Methane can directly be produced using a biocathode containing methanogens in electrochemical systems (abiotic anode) or microbial electrolysis cells (MEMCs; biotic anode) by electromethanogenesis.

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 renewable natural gas less expensive and more plentiful.

The research will continue past research by Spormann Laboratory on microbes that create methane, as well as advances in 3D-printed carbon aerogel electrode materials made by LLNL, which will be assessed for their viability in reactors.

(The LLNL researchers also have developed a new class of materials, microencapsulated carbon dioxide sorbents, that have the potential for removing carbon dioxide from mixed gas streams. The new materials could provide a more economical route for small facilities to upgrade bio-gas to purity levels that are suitable for injection into the natural gas pipeline network.)

Biogas will be supplied by Delta Diablo, a Livermore, Calif., wastewater treatment plant. 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.

—Yuri Freedman, SoCalGas senior director of business development

SoCalGas provided funding to this research to further develop the technologies known as power-to-gas (P2G), which stores excess renewable electricity as 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.

—LLNL chemist Sarah Baker

Between 3,300 and 7,800 gigawatt-hours 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 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.

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 emissions. A recent analysis found that California could achieve the same greenhouse gas reductions as electrifying buildings at a much lower cost by replacing just a fraction of the natural gas delivered through its pipelines with renewable natural gas.

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

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.

Resources

  • Shaoan Cheng, Defeng Xing, Douglas F. Call, and Bruce E. Logan (2009) “Direct biological conversion of electrical current into methane by electromethanogenesis.” 43(10) doi: 10.1021/es803531g

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