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The use of geologically stored CO2 as a geothermal heat extraction fluid can take advantage of the beneficial thermophysical characteristics of CO2 that can render it a more effective heat extraction fluid than the brine that exists in the aquifers. Some of these characteristics include a higher mobility (inverse kinematic viscosity) in reservoir conditions and a highly temperature-dependent density that can result in a naturally self-convecting thermosiphon between injection and production wells. This thermosiphon may reduce or eliminate the need for subsurface pumps—and the associated parasitic pumping power—for fluid circulation. Part of the utility of such a CO2 capture, utilization, and storage (CCUS) system is the possibility to generate baseload or dispatchable electricity with levelized costs of electricity (LCOEs) that are on par with the LCOEs of other energy technologies of regional electricity systems.
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Analytical Solutions to Evaluate the Geothermal Energy Generation Potential from Sedimentary-Basin Reservoirs
Sedimentary basins are attractive for geothermal development due to their ubiquitous presence, high perme ability, and extensive lateral extent. Geothermal energy from sedimentary basins has mostly been used for direct heating purposes due to their relatively low temperatures, compared to conventional hydrothermal systems. However, there is an increasing interest in using sedimentary geothermal energy for electric power generation due to the advances in conversion technologies using binary cycles that allow electricity generation from reservoir temperatures as low as 80 ◦C. This work develops and implements analytical solutions for calculating reservoir impedance, reservoir heat depletion, and wellbore heat loss in sedimentary reservoirs that are laterally extensive, homogeneous, horizontally isotropic and have uniform thickness. Reservoir impedance and wellbore heat loss solutions are combined with a power cycle model to estimate the electricity generation potential. Results from the analytical solutions are in good agreement with numerically computed reservoir models. Our results suggest that wellbore heat loss can be neglected in many cases of electricity generation calculations, depending on the reservoir transmissivity. The reservoir heat depletion solution shows how reservoir tempera ture and useful lifetime behave as a function of flow rate, initial heat within the reservoir, and heat conduction from the surroundings to the reservoir. Overall, our results suggest that in an exploratory sedimentary geothermal field, these analytical solutions can provide reliable first order estimations without incurring intensive computational costs.
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- Award ID(s):
- 1922666
- PAR ID:
- 10469755
- Publisher / Repository:
- Geothermics
- Date Published:
- Journal Name:
- Geothermics
- Volume:
- 116
- Issue:
- C
- ISSN:
- 0375-6505
- Page Range / eLocation ID:
- 102843
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.geothermics.2023.102843
