Advancing geothermal energy utilization opportunities: potential and strategies for integrating direct air capture

Abstract

Geothermal energy has been utilized for centuries. Prior to the industrial revolution, geothermal surface expressions were healing destinations in regions of Indigenous America, and geothermal energy was used to heat baths across the Roman empire and throughout Japan. Today, geothermal energy is harnessed for direct use in some industrial applications requiring low-grade heat as well as district heating systems, and for low-carbon electricity production, making up over 13 GW of worldwide electricity production. In the U.S., new legislation introduced incentives to promote geothermal energy as a baseload renewable electricity source. However, geothermal energy also has potential for CO₂ abatement beyond electricity generation. For example, low temperature geothermal resources can be used directly for residential heating systems, industrial processes or to power direct air capture (DAC) systems. This study explores the potential of geothermal resources to meet the thermal and electrical demands of DAC systems through the development of a geothermal-DAC evaluation framework. The framework examines configurations where binary geothermal power plants and DAC units are engineered to optimize geothermal resource use. These configurations are evaluated based on their CO₂ abatement potential, achieved by displacing carbon-intensive grid electricity and removing atmospheric CO₂. The framework was applied to two hypothetical geothermal resources, representing low (86 °C) and high (225 °C) temperature regimes for binary geothermal power plants, considering various organic Rankine cycle (ORC) working fluids. It was also tested on the Raft River binary geothermal combined cycle power plant. Results show that integrating geothermal energy with DAC systems improves CO₂ abatement potential compared to using geothermal resources solely for electricity. Improvements range from 5–757%, depending on the resource and configuration. Technoeconomic evaluations of each configuration determined the levelized cost of energy delivered to the DAC system (LCOE_DAC), ranging from $101–8579 per tCO₂. The geothermal-DAC evaluation framework highlights strategic decisions and constraints for integrating geothermal resources with DAC to maximize grid electricity production and CO₂ abatement.