Several studies suggest that CO2-based geothermal energy systems may be operated economically when added to ongoing geologic CO2 sequestration. Alternatively, we demonstrate here that CO2-Plume Geothermal (CPG) systems may be operated long-term with a finite amount of CO2. We analyze the performance of such CO2-limited CPG systems as a function of various geologic and operational parameters. We find that the amount of CO2 required increases with reservoir depth, permeability, and well spacing and decreases with larger geothermal gradients. Furthermore, the onset of reservoir heat depletion decreases for increasing geothermal gradients and for both particularly shallow and deep reservoirs.
Bibliographical noteFunding Information:
This work was supported in part by a Sustainable Energy Pathways (SEP) grant from the U.S. National Science Foundation ( NSF ) under Grant Number SEP-1230691 , by the U.S. Department of Energy ( DOE ) under Grant Number DE-EE0002764 , and by a grant from the Initiative for Renewable Energy and the Environment ( IREE ), a signature program of the Institute on the Environment (IonE) at the University of Minnesota (UMN), U.S.A. Martin Saar additionally thanks the Werner Siemens Foundation for their endowment of the Geothermal Energy and Geofluids Chair at ETH Zurich (ETHZ) and the Gibson endowment for their support of the Hydrogeology and Geofluids Research group at UMN. Any opinions, findings, conclusions, and/or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF, DOE, IREE, IonE, UMN, ETHZ, the Werner Siemens Foundation, or the Gibson Foundation. Finally, we thank the two anonymous reviewers and the Associate Editor, Dr. J.N. Moore, for their helpful comments that greatly improved this paper.
- Brine displacement
- CO geothermal
- Carbon capture and sequestration (CCS)
- Carbon capture utilization and sequestration (CCUS)
- Carbon dioxide
- Energy extraction rates
- Geothermal systems
- Reservoir simulations