Numerical Analysis of Enhanced Conductive Deep Borehole Heat Exchangers

Theo Renaud, Lehua Pan, Hannah Doran, Gioia Falcone and Patrick G. Verdin
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Theo Renaud: Energy and Power, Cranfield University, Cranfield MK43 0AL, UK
Lehua Pan: Earth Sciences Division 90-1116, Lawrence Berkeley National Laboratory, Berkeley, CA 95720, USA
Hannah Doran: James Watt School of Engineering, University of Glasgow, Glasgow G13 8QQ, UK
Gioia Falcone: James Watt School of Engineering, University of Glasgow, Glasgow G13 8QQ, UK
Patrick G. Verdin: Energy and Power, Cranfield University, Cranfield MK43 0AL, UK

Sustainability, 2021, vol. 13, issue 12, 1-21

Abstract: Geothermal energy is a reliable and mature energy source, but it represents less than 1% of the total renewable energy mix. While the enhanced geothermal system (EGS) concept faces technical validation challenges and suffers from public acceptance issues, the development of unconventional deep-well designs can help to improve their efficiency and reliability. Modelling single-EGS-well designs is key to assessing their long-term thermal performances, particularly in unconventional geological settings. Numerical results obtained with the T2WELL/EOS1 code have been validated with available experimental data from a deep borehole heat exchanger (DBHE), where a temperature of 358 ? C has been measured at a depth of 1962 m. Based on a calibrated model, the thermal performances of two enhanced thermal conductive DBHEs with graphite were compared for high geothermal gradients. The analysis highlights the potential recovery of a variable fraction of vapour. Graphite used along the well appears to be the most suitable solution to enhance the thermal output by 5 to 8% when compared to conventional wells. The theoretical implementation of such well in the Newberry volcano field was investigated with a single and doublet DBHE. The findings provide a robust methodology to assess alternative engineering solutions to current geothermal practices.

Keywords: deep borehole heat exchanger; T2Well; unconventional geothermal energy; graphite (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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