The Future of Geothermal Wellbore Integrity: Geopolymer Cements for Enhanced Stability and Hydrogen Coproduction

The transition to green hydrogen powered by geothermal systems requires robust wellbore materials capable of withstanding extreme conditions including temperatures exceeding 300°C, corrosive fluids, and thermal cycling. This review critically examines geopolymer cement, amorphous aluminosilicate binders, as high-performance alternatives to Portland cement (PC), which deteriorates at temperatures above 110°C and in saline environments. Geopolymers maintain compressive strengths greater than 50 MPa, exhibit carbon dioxide (CO₂) permeability as low as 2 × 10⁻²¹ m², and demonstrate promising thermal stability, chemical resistance, and self-healing (evidenced by permeability recovery from 9.48 to 2.76 µD). These properties together suggest strong potential to mitigate fluid migration and thermal losses, which are critical factors for sustaining efficient geothermal hydrogen production. Their production also, emits up to 80% less CO₂ than PC, supporting low carbon infrastructure goals. A full-scale field trial in the Permian basin, a technically demanding hydrocarbon region, validated the operational feasibility of geopolymer slurry using conventional cementing equipment, achieving effective placement and zonal isolation. Although, conducted outside geothermal settings, this success supports the scalability and resilience of geopolymers under harsh subsurface conditions. This review highlights, geopolymer cement’s potential to ensure long term wellbore integrity, thermal efficiency, and sustainability in geothermal hydrogen production systems.