LANZHOU, March 20 (Xinhua) -- A new study by Chinese researchers has summarized the generation mechanisms and key influencing factors of abiotic geological hydrogen, a well-concerned clean energy source amidst the global energy transition, according to the Northwest Institute of Eco-Environment and Resources (NIEER) under the Chinese Academy of Sciences.
The study also identifies promising regions for geological hydrogen exploration and development, the NIEER said. Conducted by a research team at the institute, the findings have been published in the journal Earth-Science Reviews.
Geological hydrogen plays a crucial role in Earth's energy and material cycles, significantly influencing the evolution of the planet's spheres and the formation of key mineral resources.
"Therefore, investigating the formation processes and main influencing factors of geological hydrogen is of great significance for the exploration and development of hydrogen resources, as well as for a better understanding of geochemical processes," said Li Ping, NIEER researcher.
Based on systematic review and synthesis, the study indicated that abiotic geological hydrogen is primarily generated through three pathways: hydrothermal reactions of Fe(II)-bearing minerals, water radiolysis, and radical reactions at the mineral-water interface.
According to the study, the core mechanism of hydrothermal reactions of Fe(II)-bearing minerals involves electron transfer of Fe(II) and mineral phase transitions, which are primarily controlled by temperature.
Water radiolysis generates hydrogen through the irradiation and decomposition of water by natural radioactive elements, mainly influenced by radiation type and dose.
As for the mineral-water interface radical reaction, it primarily originates from the formation of radicals through reactions of interfacial water molecules at unsaturated coordination sites, which subsequently generate hydrogen. It is mainly controlled by mineral type.
The study showed that these reactions are collectively regulated by geological environmental conditions, such as aqueous chemistry and atmospheric composition.
Based on the formation mechanisms and key influencing factors of abiotic geological hydrogen, the study team has proposed that Fe(II)-rich mafic-ultramafic rock regions, cratonic basins enriched in radionuclides, and active fault zones are more promising regions for future exploration of natural hydrogen. "It provides theoretical guidance for the exploration and development of geological hydrogen resources," said Fan Qiaohui, a NIEER researcher.
"Moreover, our study has also identified the current research gaps concerning the mechanisms, influencing factors and resource assessment of geological hydrogen, pointing out potential directions for future related studies," Fan added. ■
