Hydrogen (H₂) will play a crucial role in Europe's green energy transition, necessitating efficient storage solutions such as underground storage in salt caverns or porous media. However, the potentia Show more
Hydrogen (H₂) will play a crucial role in Europe's green energy transition, necessitating efficient storage solutions such as underground storage in salt caverns or porous media. However, the potential microbial H₂ consumption in these subsurface environments poses risks to storage stability and safety, and its magnitude remains relatively unexplored. Within the HyLife-CETP project, we developed a brine sampling protocol for the field operators and tested a standardized laboratory procedure for estimating microbial hydrogen consumption rates in these original brine samples, combining precise gas, chemical, and genetic analyses. Four labs tested and compared the developed enrichment protocol in a round-robin-like test using artificial brine and the hydrogen-consuming, sulfate-reducer Oleidesulfovibrio alaskensis as a reference strain. This test revealed consistent trends in microbial hydrogen consumption and corresponding pH increase across labs, indicating that the developed protocol effectively captures the overall microbial activity. However, inter-laboratory variability in the reported H Show less