Underground Hydrogen: New Pilots and Big Questions

Natural or geologic hydrogen has been discussed as a low-carbon energy option for industries that are hard to electrify. It is produced when water reacts with iron-rich rocks or by processes such as serpentinization, radiolysis, or mantle degassing. Interest has grown in the past two years and many start-ups have been formed; some firms have hired geoscience companies to map subsurface rock and plan pilots. One well-known commercial example is Bourakébougou in Mali, where natural hydrogen has been produced for local use.

Pilots are now being planned and tested in different regions. GeoKiln has hired Getech to map sites in Minnesota for a stimulated production pilot, and HyTerra has agreements to test gas in Kansas with a downstream partner to purify and deliver hydrogen. At the same time, national laboratories and programmes have been assembled to study underground hydrogen storage and production. Although the resource shows promise, scientists have identified major knowledge gaps about flow rates, reservoir behaviour and long-term viability since few long-term production tests exist. More field trials and life-cycle studies are required to assess costs and emissions.