Storage of Solar Thermal Energy in Borehole Thermal Energy Storage Systems

McCartney, John S.; Başer, Tuğçe; Zhan, Nan; Lu, Ning; Ge, Shemin; Smits, Kathleen M.

doi:10.22488/okstate.17.000512

Cited by 8 publications

(9 citation statements)

References 6 publications

(10 reference statements)

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“…This heat flux was converted to a volumetric heat source to obtain the value of Q in Equation (6). Although the magnitude of heat flux used in this study is representative of average value in geothermal energy storage systems (Acuña et al 2012;Welsch et al 2015;McCartney et al 2017), a constant heat flux is not expected in a system where solar thermal panels are the heat source. In these cases, the input temperature from the solar thermal panels will remain relatively constant, which means that the heat flux will decrease with time as the subsurface warms (Welsch et al 2015).…”

Section: Scenario Consideredmentioning

confidence: 99%

“…One such application is the storage of heat collected from solar thermal panels in the subsurface so that it can be harvested later (Claesson and Hellström 1981;Nordell and Hellström 2000;Chapuis and Bernier 2009). A practical mode of heat injection into the subsurface involves circulation of a heated carrier fluid through a closely-spaced array of closed-loop geothermal heat exchangers in boreholes to reach ground temperatures ranging from 35 to 80 °C (Sibbitt et al 2012;Başer et al 2016a;McCartney et al 2017). Unsaturated soils in the vadose zone are ideal thermal energy storage media because low heat losses can be expected due to the low thermal conductivity of unsaturated soils (McCartney et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Role of Nonequilibrium Water Vapor Diffusion in Thermal Energy Storage Systems in the Vadose Zone

Başer

Dong

Moradi

et al. 2018

J. Geotech. Geoenviron. Eng.

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Although siting of geothermal energy storage systems in the vadose zone may be beneficial due to the low heat losses associated with the low thermal conductivity of unsaturated soils, water phase change and vapor diffusion in soils surrounding geothermal heat exchangers may play important roles in both the heat injection and retention processes that are not considered in established design models for these systems. This study incorporates recently-developed coupled thermo-hydraulic constitutive relationships for unsaturated soils into a coupled heat transfer and water flow model that considers time-dependent, nonequilibrium water phase change and enhanced vapor diffusion to study the behavior of geothermal energy storage systems in the vadose zone. After calibration of key parameters using a tank-scale heating test on compacted silt, the ground response during 90 days of heat injection from a vertical geothermal heat exchanger

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Section: Scenario Consideredmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Nonequilibrium Water Vapor Diffusion in Thermal Energy Storage Systems in the Vadose Zone

Başer

Dong

Moradi

et al. 2018

J. Geotech. Geoenviron. Eng.

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“…Groundwater (seepage) flows can also lead to the loss of thermal energy. The studies of Xu et al [30] and Pavlov and Olesen [31] can be used to better understand the impact of advection (i.e., groundwater With an operational perspective, ideally, in BTES systems, water is used as the circulating fluid. Additionally, to have more effective heat transfer between the circulating fluid and the ground, the boreholes are usually filled with grout after U-tubes are installed.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Groundwater (seepage) flows can also lead to the loss of thermal energy. The studies of Xu et al [30] and Pavlov and Olesen [31] can be used to better understand the impact of advection (i.e., groundwater movement) and whether it should be included or not. In this study, ground water movement is assumed to be insignificant, and therefore, its advective effects are neglected.…”

Section: Model Descriptionmentioning

confidence: 99%

“…A study from solar heating collectors such as a full-scale system employed on a district heating network in Okotoks, Alberta, Canada [28]. The solar heating application has also been extensively studied both numerically [29,30] and experimentally [31,32]. Besides that, Welsch et al [33] have shown over 40% reduction in greenhouse gas emission by attaching combined heat and power (CHP) plants and/or solar thermal collectors to BTES systems.…”

Section: Introductionmentioning

confidence: 99%

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Application of Borehole Thermal Energy Storage in Waste Heat Recovery from Diesel Generators in Remote Cold Climate Locations

et al. 2019

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Remote communities that have limited or no access to the power grid commonly employ diesel generators for communal electricity provision. Nearly 65% of the overall thermal energy input of diesel generators is wasted through exhaust and other mechanical components such as water-jackets, intercoolers, aftercoolers, and friction. If recovered, this waste heat could help address the energy demands of such communities. A viable solution would be to recover this heat and use it for direct heating applications, as conversion to mechanical power comes with significant efficiency losses. Despite a few examples of waste heat recovery from water-jackets during winter, this valuable thermal energy is often discarded into the atmosphere during the summer season. However, seasonal thermal energy storage techniques can mitigate this issue with reliable performance. Storing the recovered heat from diesel generators during low heat demand periods and reusing it when the demand peaks can be a promising alternative. At this point, seasonal thermal storage in shallow geothermal reserves can be an economically feasible method. This paper proposes the novel concept of coupling the heat recovery unit of diesel generators to a borehole seasonal thermal storage system to store discarded heat during summer and provide upgraded heat when required during the winter season on a cold, remote Canadian community. The performance of the proposed ground-coupled thermal storage system is investigated by developing a Computational Fluid Dynamics and Heat Transfer model.

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Review of borehole thermal energy storage systems in unsaturated soils: Materials, mechanism, and future development

Zeng,

Cheng,

Yang

2024

Energy Storage

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Borehole thermal energy storage (BTES) is an innovative renewable energy technology for building heating and cooling. The lack of studies about BTES in unsaturated soils acts as a barrier to further implementation. In this study, the research obstacles, progress, hotspots, and differences between countries of BTES systems in unsaturated soils were described in detail based on a literature review, bibliometric analysis, technology roadmap, and data visualizations. The results show that the process of coupled heat and moisture transfer has been a research hotspot in recent years, and the thermo‐hydraulic properties increase the complexity of analysis. There are few studies on experimental data and engineering practices of BTES systems in unsaturated soils. China is leading in publications number, but European and North American countries perform better in international cooperation and policy incentives. Technology development will be directly driven by policy momentum, followed by the gradual establishment of a complete research, design, and evaluation system, which helps accelerate the replacement of traditional fossil energy with renewable energy. In an attempt to improve society's awareness and move forward with scientific foresight of BTES systems in unsaturated soils, this review has revealed the evolutionary process, identified its current status, and depicted the future development from political, economic, social, and other dimensions.

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Storage of Solar Thermal Energy in Borehole Thermal Energy Storage Systems

Abstract: This study focuses on the evaluation of solar thermal energy storage in a medium-scale soil-borehole thermal energy storage (SBTES) system installed in

Cited by 8 publications

References 6 publications

Role of Nonequilibrium Water Vapor Diffusion in Thermal Energy Storage Systems in the Vadose Zone

Role of Nonequilibrium Water Vapor Diffusion in Thermal Energy Storage Systems in the Vadose Zone

Application of Borehole Thermal Energy Storage in Waste Heat Recovery from Diesel Generators in Remote Cold Climate Locations

Review of borehole thermal energy storage systems in unsaturated soils: Materials, mechanism, and future development

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