¬Estimating Microbial Hydrogen Consumption in Hydrogen Storage in Porous Media as a Basis for Site Selection

Subsurface storage of hydrogen, e.g. in depleted gas or oil fields (DOGF), is suggested as a means to overcome imbalances between supply and demand in the renewable energy sector. However, hydrogen is an electron donor for subsurface microbial processes, which may have important implications for hydrogen recovery, gas injectivity and corrosion. Here, we review the controls on the three major hydrogen consuming processes in the subsurface, methanogenesis, homoacetogenesis, and sulfate reduction, as a basis to develop a hydrogen storage site selection tool. Testing our tool on 42 DOGF showed that ten of the fields may be considered sterile with respect to hydrogen-consuming microbiota due to either temperatures >122 °C or salinities >4.4 M NaCl. Only three fields can sustain all of the hydrogen consuming processes, due to either temperature, salinity or pressure constraints in the remaining fields. We calculated a potential microbial growth in the order of 1-17*107 cells ml-1 for these fields. The associated hydrogen consumption is negligible to small (<0.01-3.2 % of the stored hydrogen). Our results can help inform decisions about where hydrogen will be stored in the future.