Towards standardized microbial hydrogen consumption testing in the subsurface: harmonized field sampling and...

Area of Science:

• Geosciences
• Microbiology
• Energy Storage

Background:

• Hydrogen (H₂) is vital for Europe's green energy transition, requiring secure underground storage.
• Microbial H₂ consumption in storage sites poses risks to stability and safety, but is poorly understood.

Purpose of the Study:

• To develop and standardize a protocol for measuring microbial H₂ consumption in subsurface brines.
• To assess the reliability and identify challenges in quantifying microbial H₂ uptake in laboratory settings.

Main Methods:

• A novel brine sampling protocol for field operators was created.
• A standardized laboratory procedure combining gas, chemical, and genetic analyses was tested.
• A round-robin test with four labs used artificial brine and a reference sulfate-reducer strain.

Main Results:

• The protocol consistently detected microbial H₂ consumption and associated pH increases across laboratories.
• Significant inter-laboratory variability (19.8-61%) in H₂ consumption was observed, linked to metabolic activity and analytical methods.
• Abiotic hydrogen loss, especially leakage, was identified as a critical factor influencing accurate measurements.

Conclusions:

• The developed protocol is robust for studying microbial activity in underground H₂ storage systems.
• Standardization and careful control of abiotic losses are crucial for reliable H₂ consumption data.
• Understanding biological variability is essential for accurate assessment of microbial impacts on H₂ storage.