A deep reservoir for hydrogen drives intense degassing in the Bulqizë ophiolite.

Deep crustal production of hydrogen (H) is a potential source of primary energy if recoverable accumulations in geological formations are sufficiently large. We report direct measurements of an elevated outgassing rate of 84% (by volume) of H from the deep underground Bulqizë chromite mine in Albania. A minimum of 200 tons of H is vented annually from the mine's galleries, making it one of the largest recorded H flow rates to date. We cannot attribute the flux solely to the release of paleo-fluids trapped within the rocks or to present-day active and pervasive serpentinization of ultramafic rocks; rather, our results demonstrate the presence of a faulted reservoir deeply rooted in the Jurassic ophiolite massif. This discovery suggests that certain ophiolites may host economically useful accumulations of H gas.