Underground Hydrogen: New Pilots and Big Questions

Geologic hydrogen is molecular hydrogen that forms and accumulates within the Earth’s crust through processes such as serpentinization, radiolysis and mantle degassing, yet the scale of recoverable resources remains uncertain. Estimates of annual natural hydrogen generation across onshore crust average about 5,630 million cubic metres, while the portion that may be trapped in accumulations is estimated at roughly 22.5 million cubic metres per year. These figures suggest potential but also underline large gaps in spatial knowledge and longevity of flows, since most measured occurrences show low concentrations and variable flow rates.

Industry and research teams have moved quickly from theoretical studies to field pilots. GeoKiln, backed by Breakthrough Energy Fellows, has contracted Getech to map prospective sites in Minnesota for a stimulated-production pilot; modelling from early-stage projects suggests the possibility of production costs near $1.50 per kilogram of hydrogen. In the United States, HyTerra and Prometheus have agreed a 2026 demonstration in Kansas that aims to deliver purified natural hydrogen to a commercial customer. Other firms and consortia are exploring sites in Oman and elsewhere.

National laboratories and DOE-led efforts such as SHASTA are being mobilised to evaluate storage, regulatory frameworks and environmental risks, and peer-reviewed reviews have called for more field trials, techno-economic analysis and life-cycle assessment. If long-term production tests confirm stable high flow rates and if environmental impacts can be mitigated, geologic hydrogen could become a complementary, lower-emission pathway for some industrial uses.

Nevertheless, significant scientific and engineering work remains; where uncertainties persist, collaborations between private companies, national labs and academic groups will be essential to test methods, monitor subsurface impacts and build regulatory best practice before large-scale commercialisation proceeds.