How much hydrogen awaits us underground? Researchers are still sorting out the numbers. In the 1990s, Barbara Sherwood Lollar found water confined for over a billion years in the Kidd Creek mine, which turned out to be a habitat for living microbes fueled by the hydrogen produced from reactions between water and rock.

Decades later, her team revisited this data. Each of 35 boreholes consistently released an average of eight kilograms of hydrogen per year. Extrapolating that finding to over 14,000 boreholes could yield around 140 metric tons of unused gas annually. This isn’t a world-changing amount, but it’s enough to power the mine’s operations.

Other researchers have reported similar findings. Laurent Truche found at least 200 metric tons of hydrogen flowing out of the Bulqizë chromium mine in Albania each year. The challenge now is proving that this natural hydrogen can be produced economically and reliably at commercial scale, rather than just proving its existence.

Meanwhile, researchers are exploring the possibility of stimulating hydrogen production by injecting water, heat, or catalysts into reactive rocks. This could accelerate the rate of hydrogen generation by a factor of 10,000—making it commercially viable. An indication that this could work came from Oman, where gas was found to be 90% hydrogen after injecting water into rock.

The most crucial question remains: is the hydrogen rising up out of the well made through stimulation or had it been there all along?