Geothermal energy systems use the heat continually generated by the Earth as a renewable energy source. Hot geothermal fluids, mostly a mixture of water and gases that are 1–5 kilometers below the Earth’s surface, are pumped from production wells. A heat pump or similar heat exchange system extracts heat from the fluids, and the cooled fluids are returned to the subsurface via an injection well. As geothermal fluids flow from the injection well toward production wells along naturally occurring channels in the subsurface, they reabsorb geothermal energy from the surrounding rock. Some geothermal systems underperform, however, because fluids in the subsurface may flow along cooler paths that do not sufficiently reheat the fluids before they return to a production well.

A multidisciplinary team of Cornell geophysicists, chemical engineers, and materials scientists is developing a nontoxic additive for circulating geothermal fluids to improve the performance of deep-source geothermal wells. When the temperature in a particular flow path falls below a critical threshold, the additive, a silica-based particle, will swell and seal off the cooler flow path, redirecting fluids to hotter flow paths and thereby improving the system’s performance.

Geothermal energy is renewable and could decrease reliance on fossil fuels, but high drilling costs and uncertain reservoir performance have hampered the adoption of deep-source geothermal energy systems. This project supports the invention and commercialization of a nontoxic, silica-based particle to provide thermal-hydraulic control of ill-performing geothermal wells. By improving the long-term thermal performance of underperforming well pairs, this project may reduce the costs of adopting deep-source geothermal energy systems.