Producing geothermal energy with a deep borehole heat exchanger: Exergy optimization of different applications and preliminary design criteria

C. Alimonti, P. Conti and E. Soldo

Energy, 2021, vol. 220, issue C

Abstract: This paper aims at proposing fast and plain design tools to evaluate the best energy application for deep borehole heat exchangers, exploiting geothermal resources. Exergy efficiency has been chosen as a performance index. Five possible utilization solutions have been analyzed: district heating, adsorption cooling, ORC power production, a thermal cascade system, and combined heat and power configuration. An extensive sensitivity analysis on source characteristics and well geometry has been performed to find the design criteria that ensure the maximum exergy performance. Results show that configurations involving district heating are recommended for exclusive power production. If optimized, district heating exergy efficiency can reach values in the range 40%–50% when a geothermal source at the well bottom is lower than 300 °C. For higher values, the combined heat and power production is a preferable choice, reaching an exergy efficiency of up to 60%. Design charts are also provided to read first-attempt values of the well operative temperatures and flow rate to maximize exergy efficiency for each utilization layouts.

Keywords: Geothermal energy; Exergy; ORC; District heating; Absorption cooling plant; Deep borehole heat exchanger (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:220:y:2021:i:c:s0360544220327869

DOI: 10.1016/j.energy.2020.119679

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