Investigating scalability of deep borehole heat exchangers: numerical modelling of arrays with varied modes of operation

Brown, C. S. , Kolo, I. , Falcone, G. and Banks, D. (2023) Investigating scalability of deep borehole heat exchangers: numerical modelling of arrays with varied modes of operation. Renewable Energy, 202, pp. 442-452. (doi: 10.1016/j.renene.2022.11.100)

Abstract

Deep Borehole Heat Exchangers (DBHEs) are a potentially important method of developing geothermal resources through closed-loop systems for carbon neutral, spatial heating. Past research has primarily focused on single-well systems, with few investigating arrays of multiple DBHEs as a method of extracting more thermal energy. In this study, a series of arrays were modelled using OpenGeoSys software, with the aim of understanding the influence of array geometry, inter-borehole spacing and the mode of operation on the thermal performance and system efficiency. OpenGeoSys software is a finite-element model which solves thermal fluxes through the wellbore and surrounding rock using the dual-continuum method. Simulations were undertaken for the lifetime of an array (20 years) with modes of operation testing 1) long-term constant heat load application and 2) intermittent operation with 6 months of extraction followed by a recovery period. Results indicate geometry and mode of operation had a significant impact on inter-borehole spacing and system performance. For long term constant heat load application of 50 kW per DBHE, the minimal spacing required for line and square arrays should be 40 and 30 m. When considering intermittent operation, recovery periods allow replenishment of heat around the borehole, meaning smaller spacing can be utilised.

• Item Type: Articles
• Additional Information: The authors would like to show appreciation to the UKRI EPSRC (grant reference numbers EPSRC EP/T022825/1 and EPSRC EP/T023112/1) for funding this research. The funding sources are for the NetZero GeoRDIE (Net Zero Geothermal Research for District Infrastructure Engineering) and INTEGRATE (Integrating seasoNal Thermal storagE with multiple enerGy souRces to decArobonise Thermal Energy) projects, respectively.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Banks, Mr David and Kolo, Dr Isa and Brown, Dr Christopher and Falcone, Professor Gioia
• Authors: Brown, C. S., Kolo, I., Falcone, G., and Banks, D.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Renewable Energy
• Publisher: Elsevier
• ISSN: 0960-1481
• ISSN (Online): 1879-0682
• Published Online: 23 November 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Renewable Energy 202: 442-452
• Publisher Policy: Reproduced under a Creative Commons License