Solid sorbent direct air capture using geothermal energy resources (S-DAC-GT) – Region specific analysis

Abstract

This paper reviews the potential use of low temperature geothermal resources for thermal energy necessary for CO2 direct air capture (DAC) processes (geothermal DAC or S-DAC-GT). The paper includes a literature review of DAC processes and exiting techno-economic analyses on the subject. It also provides a list of global geothermal resources, maps, and databases that would be useful in finding areas of high favorability for S-DAC-GT deployment across the world. Finally, it concludes with a techno-economic analysis of four specific regions within the United States and one European region that may potentially be attractive S-DAC-GT sites: Texas Gulf Coast, Los Angeles Basin, Alaska's Cook Inlet, and Netherlands Groningen Gas Field.The objective of this paper is to provide region specific techno-economic analyses of DAC using geothermal resources. Existing DAC techno-economic analyses of DAC are region agnostic and include a breadth of energy sources. This paper provides a deeper technical and economic analysis using geothermal energy as the thermal resource for the DAC process, and the results of this paper differentiate S-DAC-GT costs and carbon intensity by region.There remains a substantial amount of uncertainty in forecasting DAC costs when deployed at scale. The goal of this paper is not to determine a precise S-DAC-GT cost. Rather, our goal is to provide indicative savings from using geothermal resources coupled with DAC, and to provide relative S-DAC-GT costs by region.Reflecting the uncertainty around the cost of DAC, our analysis suggests a S-DAC-GT cost range of $200 to $1040 per tonne CO2 captured, depending on the underlying cost model and the region of the S-DAC-GT facility. However, the savings calculated from using geothermal resources to provide the thermal energy are more consistent (Figure 1).We also analyze the relative carbon intensity of S-DAC-GT within each region. In our model, we rely on geothermal resources to provide only thermal energy for the DAC regenerative process. The carbon intensity of S-DAC-GT by region is captured in Figure 2.