A potential for climate benign direct air CO<sub>2</sub> capture with CO<sub>2</sub>-driven geothermal utilization and storage (DACCUS)
Martina Leveni, Jeffrey M. Bielicki
Abstract
Abstract To reduce the overaccumulation of carbon dioxide (CO 2 ) in the atmosphere, direct air CO 2 capture (DACC) technologies must (a) satisfy the process requirements for heat and electricity with energy that has few if any CO 2 emissions, and (b) physically isolate the CO 2 from the atmosphere after its extraction from the air. To isolate the CO 2 from the atmosphere at meaningful scale, the CO 2 will likely need to be geologically stored in deep saline aquifers. Here we propose to leverage geologic CO 2 storage (GCS) in sedimentary basin geothermal resources to produce geothermal heat and electricity for the process energy requirements of solid sorbent DACC. This sedimentary basin CO 2 -driven geothermal utilization (SB-CO 2 DGU, also known as CO 2 Plume Geothermal) circulates some of the emplaced CO 2 to extract geothermal heat in a closed loop between the subsurface reservoir and surface geothermal facility. The proposed integration of DACC and CO 2 -driven geothermal Utilization and Storage (DACCUS) adds CO 2 from the air to this closed loop system that produces renewable energy for use in the DACC process. The strategy first primes the GCS reservoir with CO 2 from large point sources, and then integrates CO 2 from DACC facility to form the DACCUS system. We focus on the process integration of DACCUS and present a case study of its potential deployment and scaling in the Gulf Coast of the United States. We combine data from prior analyses for a novel investigation of two DACCUS configurations: (1) a DACCUS heat system uses the geothermal heat to regenerate the solid sorbent in the DACC process, and (2) a DACCUS heat and power system uses the electricity generated from the produced geothermal heat for the DACC process. In general, deeper CO 2 storage reservoirs (>3.5 km) with higher geothermal temperature gradients (>35 °C km −1 ), may provide sufficient production wellhead temperatures (>100 °C), and satisfy the electric load in 93% of the combinations of reservoir characteristics we examined.