Speaker
Description
Underground hydrogen storage (UHS) in porous geological formations represents a promising solution for large-scale energy buffering in renewable-based energy systems. However, interactions between injected hydrogen (H₂) and the subsurface environment can significantly influence storage integrity and efficiency through coupled biogeochemical processes involving native microorganisms.
H₂ acts as a strong electron donor, stimulating microbial activity and modifying redox conditions within the reservoir. These changes can trigger both abiotic (mineral–chemical) and biotic (microbially mediated) reactions in subsurface systems. In particular, sulfate-reducing bacteria (SRB), methanogens, acetogenic bacteria, and iron-reducing bacteria (IRB) play a key role in these processes. Microbial consumption of H₂ may lead to the formation of byproducts such as hydrogen sulfide and methane, posing risks related to corrosion and gas contamination. In parallel, hydrogen-driven reactions can promote cycles of mineral dissolution and precipitation, potentially altering the initial petrophysical properties of the porous medium. The extent of these interactions is strongly controlled by site-specific factors, including mineralogical composition and microbial community structure.
This study investigates how mineralogical composition influences hydrogen-driven microbial processes relevant to UHS using an experimental setup based on a microfluidic system. The micromodel is functionalized with representative mineral phases to isolate the roles of surface reactivity and electron-acceptor availability during H2 and bacterial exposure. Three mineralogical configurations are examined under identical operating conditions (P ≈ 10.2 bar, T ≈ 38 °C): (i) a carbonate-functionalized system, where CaCO₃ is present as the dominant mineral phase; (ii) a sulfate-functionalized system, where CaSO₄ provides sulfate as an electron acceptor for sulfate-reducing bacteria; and (iii) a mixed carbonate–sulfate system combining CaCO₃ and CaSO₄. Following mineral functionalization, the porous micromodel is saturated with H₂ and subsequently inoculated with a strain of SRB (Oleidesulfovibrio alaskensis) as biotic component. System evolution is monitored through timelapse micrograph acquisition over a seven-day period.
The combined presence of an electron donor (H₂) and mineral-based electron acceptors can modify microbial spatial organization and activity within the porous medium, resulting in variable hydrogen consumption and the formation of secondary mineral phases that affect flow behavior. Overall, this work highlights the need for advanced experimental frameworks capable of capturing the complexity of biogeochemical interactions in UHS systems using multimineral micromodel platforms.
| Country | Norway |
|---|---|
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