A new study by Chinese researchers has summarized the generation mechanisms and key influencing factors of abiotic geological hydrogen, a clean energy source. The study also identifies promising regions for geological hydrogen exploration and development. The findings were published in the journal Earth-Science Reviews by a research team at the Northwest Institute of Eco-Environment and Resources (NIEER) under the Chinese Academy of Sciences.
Geological hydrogen plays a significant role in Earth's energy and material cycles, influencing planetary evolution and mineral resource formation.
Unpacking Generation Pathways
The study indicates that abiotic geological hydrogen is primarily generated through three distinct pathways:
- Hydrothermal reactions of Fe(II)-bearing minerals: This mechanism involves electron transfer of Fe(II) and mineral phase transitions, controlled mainly by temperature.
- Water radiolysis: Hydrogen is generated through the irradiation and decomposition of water by natural radioactive elements, influenced primarily by radiation type and dose.
- Radical reactions at the mineral-water interface: These reactions originate from the formation of radicals through interfacial water molecules at unsaturated coordination sites, subsequently generating hydrogen. This is mainly controlled by mineral type.
These reactions are collectively regulated by geological environmental conditions, including aqueous chemistry and atmospheric composition.
Identifying Promising Exploration Regions
Based on these findings, the study proposes that certain areas hold significant potential for natural hydrogen exploration:
- Fe(II)-rich mafic-ultramafic rock regions
- Cratonic basins enriched in radionuclides
- Active fault zones
The study also identified current research gaps regarding mechanisms, influencing factors, and resource assessment of geological hydrogen, suggesting directions for future studies.