Determine the replenishment rate of naturally occurring underground hydrogen

Determine at what rate geological processes produce naturally occurring underground hydrogen and whether those processes can replenish a hydrogen reservoir as it is exploited.

Background

The paper considers naturally occurring underground hydrogen as a potentially low-carbon energy reserve for periods when renewable generation and batteries are insufficient. Unlike manufactured green hydrogen, natural hydrogen would not require electrolysis, but its sustainability depends on the rate at which geological processes generate it and whether extraction can be maintained without depleting the resource. The authors explicitly identify both the production rate and the possibility of reservoir replenishment as unknowns.