Closed-loop geothermal system is a potential source of low-carbon renewable energy.

Abstract

Decarbonizing the energy sector requires renewable sources that are economic and responsive to demand. Intermittency and seasonal variability, therefore, limit the potential of wind and solar. Geothermal energy can potentially provide low-carbon renewable power that is dispatchable and responsive to demand. However, conventional geothermal methods require high permeability in high-temperature subsurface zones, which restricts their application. Here, we assess the global potential of the closed-loop geothermal system (CLGS), an emerging technology that does not require high permeability. Using thermodynamic, process, and technoeconomic modeling, we analyze the potential for CLGS in 12,000 candidate regions to estimate global viability. With the base case of water as the working fluid in a Rankine cycle, we estimate the global potential to be 9 TWe, equivalent to 70% of current electricity production. We assess using phase change working fluids to broaden applicability and improve efficiency, and evaluate the remaining technological barriers to closed-loop geothermal energy production.