Identifying and Understanding Microbial Methanogenesis in CO₂ Storage

Area of Science:

• Geological storage of carbon dioxide (CO2)
• Subsurface biogeochemistry
• Microbial impacts on energy storage

Background:

• Carbon capture and storage (CCS) is vital for net-zero strategies, relying on safe geological storage.
• Current CCS research primarily addresses CO2 physiochemical behavior, overlooking microbial impacts.
• Subsurface microbial processes, like methanogenesis, can significantly affect CO2 storage.

Purpose of the Study:

• To review the impact of microbial methanogenesis on CO2 storage in geological systems.
• To assess the scale and geological settings of methanogenesis relevant to CO2 storage.
• To identify knowledge gaps and suggest future research directions.

Main Methods:

• Literature review of microbial methanogenesis in geological CO2 storage.
• Analysis of factors influencing methanogenesis kinetics and energetics (e.g., H2 availability).
• Evaluation of methanogenesis potential across different geological storage types.

Main Results:

• Methanogenesis is possible in all geological CO2 storage types, but often limited by hydrogen (H2) generation.
• Hydrogen bioavailability, and thus methanogenesis potential, is highest in depleted hydrocarbon fields and lowest in saline aquifers.
• Microbial activity can alter fluid composition and dynamics, potentially reducing storage capacity and changing CO2 mobility.

Conclusions:

• Microbial methanogenesis poses a potential risk to the efficacy and safety of geological CO2 storage.
• Integrated monitoring for biogeochemical processes is essential for effective CO2 storage management.
• Further research is required to fully understand and mitigate the impacts of microbial methanogenesis on CO2 storage sites.