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A key challenge in the 21st century is the successful implementation of the energy transition, which hinges on the development of sustainable (energy) resources. In this context, hydrogen gas (H2) generated by natural processes is a promising source of clean energy. However, we urgently need to develop the concepts and exploration strategies for this promise of natural H2 energy to become a reality.The most likely mechanism of large-scale natural H2 generation in nature is the serpentinization of ultramafic mantle rocks during their chemical reaction with water. In order to predict the bulk serpentinization and natural H2 generation that may lead to the development of exploitable H2 deposits, we consider the following “recipe” for efficient serpentinization, which involves three main ingredients: (1) (fresh) mantle rocks that need to be at (2) optimal temperatures between ca. 200-350˚C (the serpentinization window), and (3) in contact with ample water for the reaction to take place. The serpentinization window can be expected at 8-12 kilometers below the Earth’s surface. However, mantle rocks are normally found at much greater depth; thus these rocks must be brought closer to the surface (exhumed) through geodynamic processes. Moreover, water needs to reach such depths along large faults or other structures that cut into the exhumed mantle. The challenge we are faced with is to understand where (and when) these ingredients may come together in nature, and how much natural H2 may be generated.Numerical geodynamic modelling is an ideal means to tackle this issue since it allows us not only to test how mantle rocks can be exhumed, but also to trace the temperature conditions and potential water availabilitiy (Zwaan et al. 2025). By combining this information, we assess favorable settings and timing of bulk natural H2 generation in different geodynamic systems. Subsequently, we consider where the natural H2 could be exploited. The serpentinizing mantle source rocks at 8-12 km depth cannot be directly targeted. Ideally, the natural H2 would instead migrate and accumulate in sedimentary reservoir rocks at depths of only a couple of kilometers that are connected with the mantle source rocks via migration pathways (e.g., faults). Importantly, all key elements need to be in place for the system to work.Our first-order modelling work and the development of natural H2 system concepts greatly helps to direct natural H2 resource exploration efforts, for example in the Alps and Pyrenees. Moreover, substantial opportunity lies in refining both the geodynamic modelling and natural H2 system analysis, in field- and laboratory testing of our H2 system concepts, and in extending such a “mineral system” modelling approach to other types of natural resources that are crucial to the energy transition. Reference:Zwaan, F., Brune, S., Glerum, A.C., Vasey, D.A., Naliboff, J.B., Manatschal, G., & Gaucher, E.C. 2025: Rift-inversion orogens are potential hot spots for natural H2 generation, Science Advances, 11, eadr3418. https://doi.org/10.1126/sciadv.adr3418