On the importance of the thermosiphon effect in CPG (CO2 plume geothermal) power systems

Adams, Benjamin M.; Kuehn, Thomas H.; Bielicki, Jeffrey M.; Randolph, Jimmy B.; Saar, Martin O.

doi:10.1016/j.energy.2014.03.032

Cited by 116 publications

(70 citation statements)

References 18 publications

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“…Therefore, systems with low pore-fluid pressure drops between the wells imply high mobility of CO2. This results in a strong thermosiphon and reduces pumping power requirements [6]. The pore-fluid pressure drop between the wells in systems with low-permeability layers at the top of the reservoir is greater than in systems with highpermeability layers at the top.…”

Section: Discussionmentioning

confidence: 98%

“…This detriment, however, is likely overcome by the large accessible volume of natural reservoirs, allowing the total heat energy output of natural reservoirs to potentially surpass that of artificial basins. Furthermore, supercritical CO2 has a high mobility (i.e., low kinematic viscosity) and high thermal expansibility compared to water, resulting in the formation of a strong thermosiphon [6,9,10] that typically eliminates parasitic pumping requirements. Both effects tend to significantly increase electricity production efficiency.…”

Section: Introductionmentioning

confidence: 99%

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CO2-Plume Geothermal (CPG) Heat Extraction in Multi-layered Geologic Reservoirs

et al. 2014

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CO2-Plume Geothermal (CPG) technology involves injecting CO2 into natural, highly permeable geologic units to extract energy. The subsurface CO2 absorbs heat from the reservoir, buoyantly rises to the surface, and drives a power generation system. The CO2 is then cooled and reinjected underground. Here, we analyze the effects of multi-layered geologic reservoirs on CPG system performance by examining the CO2 mass fraction in the produced fluid, pore-fluid pressure buildup during operation, and heat energy extraction rates. The produced CO2 mass fraction depends on the stratigraphic positions of highly permeable layers which also affect the pore-fluid pressure drop across the reservoir.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

CO2-Plume Geothermal (CPG) Heat Extraction in Multi-layered Geologic Reservoirs

et al. 2014

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“…The artificially enhanced permeability needs to be high enough to reach flow rates that are commercially relevant for power production, depending on the subsurface working fluid. Larger permeability enhancements are required for water or brine than for CO 2 , as the latter can utilize lower temperatures and lower permeabilities for economic geothermal power generation, due to its higher energy conversion efficiency (Brown, 2000;Pruess, 2006Pruess, , 2007Randolph and Saar, 2011a, b;Adams et al, 2014Adams et al, , 2015Garapati et al, 2015;Buscheck et al, 2016). Moreover, fluid flow should occur within a large number of permeable fracture pathways that sweep a large surface area of the rock, thereby providing longevity to the system and avoiding early thermal breakthrough, such as occurred at the Rosemanowes Project (Parker, 1999) and the Hijiori Project (Tenma et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

The seismo-hydromechanical behavior during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in situ stimulation experiment

et al. 2018

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Abstract. In this contribution, we present a review of scientific research results that address seismo-hydromechanically coupled processes relevant for the development of a sustainable heat exchanger in low-permeability crystalline rock and introduce the design of the In situ Stimulation and Circulation (ISC) experiment at the Grimsel Test Site dedicated to studying such processes under controlled conditions. The review shows that research on reservoir stimulation for deep geothermal energy exploitation has been largely based on laboratory observations, large-scale projects and numerical models. Observations of full-scale reservoir stimulations have yielded important results. However, the limited access to the reservoir and limitations in the control on the experimental conditions during deep reservoir stimulations is insufficient to resolve the details of the hydromechanical processes that would enhance process understanding in a way that aids future stimulation design. Small-scale laboratory experiments provide fundamental insights into various processes relevant for enhanced geothermal energy, but suffer from (1) difficulties and uncertainties in upscaling the results to the field scale and (2) relatively homogeneous material and stress conditions that lead to an oversimplistic fracture flow and/or hydraulic fracture propagation behavior that is not representative of a heterogeneous reservoir. Thus, there is a need for intermediate-scale hydraulic stimulation experiments with high experimental control that bridge the various scales and for which access to the target rock mass with a comprehensive monitoring system is possible. The ISC experiment is designed to address open research questions in a naturally fractured and faulted crystalline rock mass at the Grimsel Test Site (Switzerland). Two hydraulic injection phases were executed to enhance the permeability of the rock mass. During the injection phases the rock mass deformation across fractures and within intact rock, the pore pressure distribution and propagation, and the microseismic response were monitored at a high spatial and temporal resolution.

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“…brine or hydrocarbons). In this so-called CO 2 -plume geothermal (CPG) approach (Randolph and Saar 2011a, b;Adams et al 2014;Ganjdanesh et al 2015) the working fluid is not necessarily CO 2 only, and contrary to the first application, a key objective is to provide simultaneous CO 2 -injection-induced pressure relief by producing hot brine with consumptive beneficial uses (Buscheck et al 2012b). The purpose also shifts to maximise brine production (i.e.…”

Section: Introductionmentioning

confidence: 99%

Integrated Carbon Sequestration–Geothermal Heat Recovery: Performance Comparison Between Open and Close Systems

Babaei

2018

Transp Porous Med

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In this paper, the lateral boundaries for a theoretical homogeneous, isotropic, horizontal, 3-dimensional sedimentary hot aquifer were prescribed by either unhindered open to fluid and heat flow, or compartmentalised fully close boundary conditions. CO 2 injection was administered through three well patterns of varying well spacing and numbers: 3 × 3 (5 injection wells and 4 production wells, 750-m well spacing), 5 × 5 (13 injection wells and 12 production wells, 500-m well spacing), and 7 × 7 (25 injection wells and 24 production wells, 375-m well spacing). To assess the effects of boundary conditions and well spacing on a combined carbon sequestration-geothermal heat recovery process, number of output metrics such as net cumulative CO 2 stored, volumetric storage efficiency, geothermal heat recovery and pressure build-up were quantified in 54 simulation runs. Based on the assumption made and conditions that the simulation, it was shown that for a typical and more common fewer well number cases, the open versus close boundaries have critical role in determining the effectiveness of operation. (a) Open boundary conditions may counter-intuitively lead to heat recovery relative deficiencies if the pressure gradient stays largely towards the outside of the system (pressure of system > pressure of surrounding). This, however, will benefit CO 2 injectivity and storage efficiency by providing escape paths for fluids (CO 2 and brine). (b) Close boundary conditions will universally be beneficial for fluid and heat production purposes; however, the excessive pressure build-up can significantly affect the operation duration length. For economically unjustifiable cases with high number of wells, the effects of boundary conditions were shown to be reduced by effective fluid extraction from the medium, thereby enhancing the geothermal heat recovery and avoiding pressure build-up. The research delineated no significant effect of boundary conditions on salt precipitation.Keywords Carbon sequestration in geothermal aquifers · Geothermal heat recovery · Open and close boundary conditions · CO 2 -plume geothermal · CO 2 storage efficiency · Thermal numerical simulation B Masoud Babaei

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On the importance of the thermosiphon effect in CPG (CO2 plume geothermal) power systems

Cited by 116 publications

References 18 publications

CO2-Plume Geothermal (CPG) Heat Extraction in Multi-layered Geologic Reservoirs

CO2-Plume Geothermal (CPG) Heat Extraction in Multi-layered Geologic Reservoirs

The seismo-hydromechanical behavior during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in situ stimulation experiment

Integrated Carbon Sequestration–Geothermal Heat Recovery: Performance Comparison Between Open and Close Systems

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