Researchers are exploring a dual-benefit process that captures carbon dioxide by storing it in rocks while simultaneously extracting hydrogen gas, creating potential climate and energy advantages in a single operation.

The process exploits the chemical reactions that occur when CO2 interacts with certain rock types underground. When carbon dioxide is injected into geological formations, it reacts with minerals in the rock, becoming permanently sequestered while releasing hydrogen as a byproduct. This approach addresses two pressing challenges simultaneously: removing greenhouse gases from the atmosphere and generating clean hydrogen fuel.

Multiple research groups are advancing this technology toward commercial viability. The hydrogen produced can be used as a zero-carbon energy source for industrial applications, transportation, or electricity generation. Some teams report that the geological heat from deep rock formations could generate geothermal power as an additional benefit, making the overall process triply advantageous.

The chemistry relies on specific rock types, particularly ultramafic rocks rich in iron and magnesium minerals, though researchers continue investigating other geological candidates. When pressurized CO2 contacts these minerals at depth, oxidation-reduction reactions occur that break molecular bonds, liberating hydrogen while the carbon becomes locked in mineral form.

The approach differs from conventional carbon capture and storage, which simply sequesters CO2 without generating useful products. By creating hydrogen alongside permanent carbon storage, the process improves economic viability and reduces reliance on hydrogen production methods that currently depend on fossil fuels.

Scaling challenges remain substantial. The process requires injecting large CO2 volumes into suitable geological formations at precise depths and temperatures. Identifying appropriate rock formations with adequate permeability and volume presents logistical hurdles. Engineers must also optimize reaction kinetics to ensure commercially viable timescales for hydrogen recovery.

If successfully deployed at scale, this technology could transform how society addresses climate change while developing alternative energy sources. Several pilot projects are currently testing the concept in different geological