Meeting Net-Zero America Direct Air Capture Targets with Sedimentary Basin Geothermal Heat While Considering Environmental Justice

Abstract

Sedimentary basins are ubiquitous, naturally porous and permeable, but the geothermal heat in these basins is understudied because it is generally regarded as too cold for cost-competitive electricity generation. Here, we investigate the potential of using this heat resource to drive solid-sorbent (a.k.a. “low-temperature”) direct air capture (DAC). DAC removes CO2 from the air using machines built for that purpose, and capturing and storing hundreds of millions of tonnes of CO2 via DAC may be required to reach a net-zero emission economy in the USA. We estimate the capacity of solid-sorbent DAC in the United States that could be driven by sedimentary basin heat in three steps: 1) we modify the generalizable GEOthermal techno-economic simulator (genGEO) for direct-use geothermal applications; 2) apply direct-use genGEO results across the Sequestration of CO2 Tool (SCO2T) geodatabase of sedimentary basin properties; and 3) integrate those heat results with a previously published model of a solid-sorbet DAC system. We then estimate the total cost of sedimentary-basin-driven DAC geospatially across the United States using 2050 projected electricity prices from the Low-Carbon Resource Initiative Net-Zero America Study, and the cost of CO2 storage estimated with SCO2T. Lastly, we consider the implications that considering environmental justice may have on reaching net-zero DAC targets by varying the portion of the sedimentary basin geothermal resource that may be used based on the location of disadvantaged communities. We find that the cost and capacity of DAC can change geospatially depending on the cost and quantity of sedimentary basin heat, but that this heat resource can provide sufficient thermal energy to meet net-zero capacity targets. Depending on how environmental justice is considered, the cost of sedimentary-basin-driven DAC could increase by tens to thousands of dollars per tonne of CO2.