Environmental and economic assessment of borehole thermal energy storage in district heating systems

Welsch, Bastian; Göllner-Völker, Laura; Schulte, Daniel O.; Bär, Kristian; Sass, Ingo; Schebek, Liselotte

doi:10.1016/j.apenergy.2018.02.011

Cited by 96 publications

(39 citation statements)

References 58 publications

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“…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. McDaniel et al [34] have shown the improvement in the flexibility of operating a CHP plant (combination of a gas turbine, a high-pressure steam turbine, and a low-pressure steam turbine) by coupling with a BTES system where it has replaced burning fossil fuel for heating purposes.…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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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“…Further reviews of the state of the art of BTES have been extensively published by [31][32][33][34][35][36][37][38][39][40][41][42][43].…”

Section: Introduction and Terminologymentioning

confidence: 99%

Design Considerations for Borehole Thermal Energy Storage (BTES): A Review with Emphasis on Convective Heat Transfer

et al. 2019

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Borehole thermal energy storage (BTES) exploits the high volumetric heat capacity of rock-forming minerals and pore water to store large quantities of heat (or cold) on a seasonal basis in the geological environment. The BTES is a volume of rock or sediment accessed via an array of borehole heat exchangers (BHE). Even well-designed BTES arrays will lose a significant quantity of heat to the adjacent and subjacent rocks/sediments and to the surface; both theoretical calculations and empirical observations suggest that seasonal thermal recovery factors in excess of 50% are difficult to obtain. Storage efficiency may be dramatically reduced in cases where (i) natural groundwater advection through the BTES removes stored heat, (ii) extensive free convection cells (thermosiphons) are allowed to form, and (iii) poor BTES design results in a high surface area/volume ratio of the array shape, allowing high conductive heat losses. The most efficient array shape will typically be a cylinder with similar dimensions of diameter and depth, preferably with an insulated top surface. Despite the potential for moderate thermal recovery, the sheer volume of thermal storage that the natural geological environment offers can still make BTES a very attractive strategy for seasonal thermal energy storage within a “smart” district heat network, especially when coupled with more efficient surficial engineered dynamic thermal energy stores (DTES).

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“…The tank TES and pit TES are built independently from the aquifer geological conditions and unaffected by the groundwater flow due to an insulation layer bounded outside of the container. The borehole TES is a closed‐loop system to store energy via the ground heat exchangers in the aquifer and supply buildings for heating or cooling (Bayer et al, 2016; Beier et al, 2013; Beier & Spitler, 2016; Rivera et al, 2016; Welsch et al, 2018). The ATES is an open loop system and known for its potential for the large‐scale and long‐term energy storages.…”

Section: Introductionmentioning

confidence: 99%

Analytical Model for Heat Transfer Accounting for Both Conduction and Dispersion in Aquifers With a Robin‐Type Boundary Condition at the Injection Well

Lin

Yeh

2019

Water Resources Research

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In the past, the analytical model developed for a radially divergent heat flow in an aquifer thermal energy storage (ATES) system considers only the process of either thermal conduction or thermal dispersion. In addition, the existing models commonly regarded the inner boundary at the injection well as the constant‐temperature condition, which does not meet the continuity condition of heat flux at the wellbore. We herein propose an analytical model for a realistic representation of heat flow in an ATES system by considering the effects of both thermal conduction and thermal dispersion in the heat transfer equation and a Robin‐type boundary condition at the injection well. The model consists of three heat flow equations depicting the temperature distributions in the confined aquifer and its underlying and overlying rocks. The Laplace transform method is applied to solve the proposed model. The solutions for the cases of dispersion‐ and conduction‐dominant flow fields are also developed and discussed. Comparisons between the present solutions with five existing solutions developed for similar heated water injection problems are made. A global sensitivity method is also performed to analyze the thermal response to the change in each of the aquifer parameters. Finally, our solution is validated through the comparison with the finite difference solution and observed data from an ATES experiment site in Mobile, Alabama.

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Environmental and economic assessment of borehole thermal energy storage in district heating systems

Cited by 96 publications

References 58 publications

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

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

Design Considerations for Borehole Thermal Energy Storage (BTES): A Review with Emphasis on Convective Heat Transfer

Analytical Model for Heat Transfer Accounting for Both Conduction and Dispersion in Aquifers With a Robin‐Type Boundary Condition at the Injection Well

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