The paper discusses Hydrogen energy and geological carbon retention using a biogas-geothermal wellbore reformation tool.

Enhancing overall resource efficiency contributes significantly to energy security. Biogas serves as a critical energy asset within waste management by converting diverse organic wastes into higher value products. Through the establishment of integrated partnerships, sector coupling underscores the synergies among geothermal energy, district heating, industry-related CO₂, urban biowaste, and agriculture. This innovative geothermal approach — applied to wellbore biogas reformation — facilitates hydrogen production alongside point-of-use geological carbon capture and storage (CCS). The Carbon Injection and Gasification Geothermal (CIGG) methodology offers a direct and effective pathway towards net zero by merging biogas reformation and carbon capture with low-grade district heat geothermal systems. This approach streamlines the hydrogen generation and CCS systems by eliminating unnecessary surface process steps, while incorporating reservoir heat storage and recovery, thereby reducing process energy consumption, costs, and material use, and results in an integrated, more energy efficient and sustainable solution.

To realise these synergies, a specialised wellbore tool for biogas (methane) reformation is under development, designed to leverage the natural properties of a geothermal reservoir formation and its fluids (i.e., heat storage, geothermal pressure, and temperature). The reformation’s resulting hot CO₂ waste stream from this tool is injected into the reservoir, for heat storage and later recovery. This mitigates the reservoir rock’s temperature depletion typically observed from long term production of geothermal power fluids. Moreover, this immediate, in situ downhole CO₂ capture will enable improved geothermal power efficiencies through enhanced heat recovery utilising the power fluid. As geothermal wells generally possess a lifespan of 15 to 25 years, integrating these processes bolsters long-term energy security. Overall, the CIGG process represents a mutually beneficial advancement for both energy sectors and environmental stewardship.