Advisor: Dr. Jennifer Wilcox and Dr. Peter Psarras – Chemical and Biomolecular Engineering department at University of Pennsylvania

This project investigates the potential of combining geothermal energy with direct air capture (DAC) as a decarbonization strategy for large-scale CO₂ removal. The research focuses on the feasibility of using geothermal energy to meet both the low-grade heat requirements and the electricity requirements for DAC installations, while monitoring the reinjection temperatures and preventing scaling from mineral-rich brine. The methodology evaluates multiple configurations for integrating DAC with binary geothermal power plant infrastructure, including parallel and series configurations. A high-temperature (225ºC) and a low-temperature (86ºC) geothermal reservoir are investigated to provide bookend scenarios for a geothermal-DAC integration application. Furthermore, a mid-range geothermal reservoir temperature was tested in conjunction with the well-documented Raft River binary combined cycle power plant to illustrate the flexibility of DAC using high-enthalpy or low-enthalpy brine for meeting thermal energy requirements.

The key parameters that were highlighted in these studies include the total CO₂ abatement potential of each test case, in comparison to the geothermal energy power plant solely producing grid electricity and the levelized cost of energy delivered to the DAC system. The total CO₂ abatement potential was determined based on the CO₂ emissions reductions, from dispatching excess electricity to the grid, CO₂ removals, from the DAC facility, the embodied CO₂ emissions from the installation infrastructure, and the opportunity cost emissions when additional no-carbon electricity sources are required to account for the fact they could have been deployed for grid decarbonization rather than DAC.

The analysis shows that integrating DAC with geothermal energy power plants to meet both thermal and electrical requirements, improves the CO₂ abatement potential from 5% to 75o%, depending on the geothermal resource and the configuration utilized. Furthermore, the technoeconomic evaluations for each configuration determined the levelized cost of energy delivered to the DAC system ranged from $101 – 8,569/tCO₂, illustrating those at the lower end may be cost competitive with other energy sourcing strategies. Lastly, The Geothermal-DAC Evaluation Framework highlights strategic decisions and constraints for integrating geothermal resources with DAC to maximize grid electricity production, CO₂ abatement, technoeconomic performance, and has the ability to be expanded to consider community and local benefits.

Read the Blog Post Here!

Read the Full Paper Here!