Researchers are investigating whether naturally occurring underground hydrogen can be captured and used as a zero-carbon fuel source.

Geochemists and startups are exploring the potential of "geologic hydrogen," a gas produced deep within the Earth's crust through chemical reactions with iron-rich rock or radioactive decay. While the US Geological Survey estimates trillions of tons of hydrogen exist underground, researchers are currently working to determine if these reservoirs can be tapped economically and reliably at a commercial scale.

Evaluating Underground Potential

At the Kidd Creek mine in Ontario, researchers Barbara Sherwood Lollar and Oliver Warr analyzed data from 35 boreholes collected over more than a decade. They found that each borehole released an average of eight kilograms of hydrogen annually. Extrapolating this to the mine's 14,000 boreholes suggests approximately 140 metric tons of hydrogen flow from the mine each year. While not a global solution, researchers suggest this could power a portion of the mine's operations as a demonstration of the technology. Similar findings have been reported elsewhere, including at the Bulqizë chromium mine in Albania, where researchers identified an annual flow of at least 200 metric tons of hydrogen. Experts note that these findings confirm natural hydrogen generation is a genuine geological process, though the challenge of commercial viability remains.

Stimulation and Exploration Efforts

Beyond searching for existing reservoirs, researchers are testing methods to stimulate hydrogen production by injecting water, heat, or catalysts into reactive rocks. ARPA-E is currently funding over a dozen projects with the goal of accelerating natural hydrogen-producing reactions by a factor of 10,000. In a recent test in Oman, researchers injected 50,000 cubic meters of water into a one-kilometer borehole. When the well was opened months later, the gas released was 90% hydrogen. Scientists are now working to determine if this hydrogen was produced by the stimulation process or if it was already present in the rock.