Please use this identifier to cite or link to this item: https://doi.org/10.21256/zhaw-23155
Publication type: Article in scientific journal
Type of review: Peer review (publication)
Title: Control-oriented modelling and operational optimization of a borehole thermal energy storage
Authors: Fiorentini, Massimo
Baldini, Luca
et. al: No
DOI: 10.1016/j.applthermaleng.2021.117518
10.21256/zhaw-23155
Published in: Applied Thermal Engineering
Volume(Issue): 199
Issue: 117518
Issue Date: 25-Nov-2021
Publisher / Ed. Institution: Elsevier
ISSN: 1359-4311
1873-5606
Language: English
Subjects: Seasonal thermal energy storage; Energy optimization; Multi-energy systems; Renewable energy; CO2 emission reduction
Subject (DDC): 621.04: Energy engineering
Abstract: Seasonal thermal energy storage is an effective measure to enable a low carbon future through the integration of renewables into the energy system. Borehole thermal energy storage (BTES) provides a solution for long-term thermal energy storage and its operational optimization is crucial for fully exploiting its potential. This paper presents a novel linearized control-oriented model of a BTES, describing the storage temperature dynamics under varying operating conditions, such as inlet temperature, mass-flow rate and borehole connection layouts (e.g. in-series, in-parallel or mixed). It supports an optimization framework, which was employed to determine the best operating conditions for a heat pump-driven BTES, subject to different  intensity profiles of the electricity. It was demonstrated that this boundary condition, due to its seasonal variation, is critical for the optimal operation of the system, as increasing heat pump efficiency in winter while accepting a lower one in summer can be beneficial. Results for an exemplary district case, subject to two different  intensity profiles, show that a lower relative intensity in summer compared to the one in winter leads to a higher optimal operating temperature of the storage. The district system studied is heating-dominated, effectively enabling the BTES to cover only 20% of the total heat demand, leading to limited total yearly CO2 emissions savings of 2.2% to 4.3%. When calculating the benefits associated with the heating and cooling demand handled by the BTES, a higher  emission reduction in the range of 12.8%–19.9% was found. This highlights the BTES potential when subject to more balanced loads. 
URI: https://digitalcollection.zhaw.ch/handle/11475/23155
Fulltext version: Published version
License (according to publishing contract): CC BY 4.0: Attribution 4.0 International
Departement: Architecture, Design and Civil Engineering
Organisational Unit: Centre for Building Technologies and Processes (ZBP)
Appears in collections:Publikationen Architektur, Gestaltung und Bauingenieurwesen

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