“This new research advances our understanding of suitable environments for natural hydrogen generation,” said Sascha Brune, section chief of the Geodynamic Modelling Section at GFZ, in a statement that captures a swelling sense of possibility among geoscientists and energy planners. By 2025, the idea that mountain ranges may be gigantic, untapped reservoirs of natural hydrogen is no longer the stuff of science fiction but a diligently modeled scientific hypothesis, with the Pyrenees, Alps, and Himalayas standing out as targets for investigation.
The science is founded on the geodynamics of plate tectonics and the geochemical alchemy of serpentinization. Essentially, serpentinization is the reaction of ultramafic mantle rocks that are rich in olivine and pyroxene with water, which result in serpentine minerals and the release of molecular hydrogen. The efficacy of the reaction depends on temperature, water content, and rock composition. As outlined in a recent paper in Science Advances, the most efficient “serpentinization window” is between 200°C and 350°C, a temperature regime more typical of mountain-building orogenic belts than rift basins or mid-ocean ridges.
Geodynamic modeling, utilizing high-end software such as ASPECT and FastScape, has allowed scientists to model the tectonic evolution of rift-inversion orogens areas where ancient rift basins are compressed and pushed upwards to form mountains. These models follow the exhumation of the mantle rocks, the development of fault networks, and the thermal evolution of the crust, identifying where and when the mantle material is both exposed and ready for serpentinization. Based on such simulations, the potential for hydrogen production in mountain belts is potentially 20 times larger than in rift settings, due to a combination of geotherms which are cooler, the presence of plentiful meteoric water, and widespread faulting that allows water-rock interactions.
The Pyrenees, for instance, have a well-documented exhumed mantle mass exposed over the Mauléon Basin, where active serpentinization is suspected to produce significant amounts of hydrogen. Modeling indicates that such a body, 10 kilometers long along strike, might generate as much as 3 × 1011 moles of hydrogen per year a caloric equivalent to satisfy annual energy requirements of a mid-European city. Comparable geological arrangements occur in the Alps and the western Himalayas, where exhumed mantle wedges and thick sedimentary covers form both the source and the trap for hydrogen entrapment.
The geochemical specifics are equally compelling. Laboratory and field studies have established that serpentinization of mantle peridotite can yield between 100 and 300 millimoles of hydrogen per kilogram of rock, depending on the degree of iron oxidation and the presence of minerals such as magnetite and cronstedtite. In mountain environments, the interaction of tectonic uplift, erosion, and sedimentation provides a dynamic system in which new mantle rocks are constantly exposed to percolating water, maintaining hydrogen generation over millions of years. In addition, the occurrence of thick sequences of sediments sandstones and clays offers both reservoir and seal, allowing development of drillable subsurface hydrogen accumulations similar to conventional petroleum systems.
The technological implications are significant. “Crucial to the success of these efforts will be the development of novel concepts and exploration strategies. Of particular importance is how the formation of economic natural H2 accumulations is controlled by the tectonic history of a given exploration site,” stressed GFZ study lead author Frank Zwaan. The following front, then, is not so much to affirm the existence of hydrogen but to chart its migration routes, evaluate reservoir potential, and work out ways of safe and effective extraction.
This paradigm shift is already shaping exploration campaigns. Initial indications of natural hydrogen have been found in the Pyrenees, Alps, and Balkans, with the result that a rush of interest has been gained both from public research consortia and private clean-tech investors. The analogy with the early days of the oil industry is not lost on experts; as Zwaan put it, “we could be witnessing the birth of a new natural hydrogen industry.”
The wider geoscientific framework underlines the importance of these results. Although rifted margins and mid-ocean ridges have been known to be areas of serpentinization and hydrogen flux, their deep-water, offshore environments present stern tests for economic recovery. Mountain belts, on the other hand, provide accessible, onshore targets where the convergence of geodynamic modeling, geochemical analysis, and advanced drilling technology may open up a new era of sustainable energy production. As the pace of demand for green hydrogen quickens, the world’s orogenic belts might soon be seen not only as beautiful vistas, but as essential drivers in the world energy transition.
