Underground Bio-methanation Technology Holds Promise for Renewable Energy and Carbon Utilization

Researchers from the Clausthal University of Technology in Germany have made significant findings on the emerging technology of underground bio-methanation, which enables the production of renewable natural gas, large-scale renewable energy storage, and carbon utilization and sequestration. However, the study reveals that microbial competition during the UBM process can affect methane production. The research team developed a microbial kinetic model to investigate this competition, providing valuable insights for site selection and optimal design in the implementation of UBM.

Key Takeaways:

• The study revealed that sulfate-reducing bacteria's H2 consumption is primarily limited by sulfate availability in formation water, whereas acetogen metabolism can significantly affect conversion efficiency.
• In the absence of carbonate minerals, pH reduction from acetogen metabolism may even halt the conversion process.
• Increased salinity, particularly above 90 g/L, along with a higher CO2/H2 ratio, can inhibit methanogen activity, potentially leading to more substrate being converted into acetate.
• The injection ratio for fully consuming both CO2 and H2, accounting for C/H needs in biomass synthesis, is 1:3.78.
• A larger maximum biomass capacity enables methanogens to quickly consume all CO2 and H2, reducing competition from other microbes.
• The study's findings provide valuable insights for site selection and optimal design in the implementation of UBM.
• The research concluded that UBM has the potential to enable renewable natural gas production, large-scale renewable energy storage, and carbon utilization and sequestration.

Statistics:

• The study found that the injection ratio for fully consuming both CO2 and H2 is 1:3.78.
• The maximum biomass capacity is crucial for methanogens to quickly consume all CO2 and H2, reducing competition from other microbes.
• The research showed that increased salinity above 90 g/L can inhibit methanogen activity by 10-15%.

Sources:

• Impacts of Microbial Competition On Underground Bio-methanation of Hydrogen and Carbon Dioxide: Insights From Biogeochemical Simulations. Renewable Energy, 2025;251.
• Clausthal University of Technology, Inst Subsurface Energy Syst, D-38678 Clausthal Zellerfeld, Germany.
• European Union (EU).
• China Scholarship Council.