On the limitations of closed-loop geothermal systems for electricity generation outside high-geothermal gradient fields

• Published in: Communications engineering Vol. 4; no. 1; pp. 116 - 11
• Main Authors: Tangirala, Sri Kalyan, Vilarrasa, Víctor
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2025; Springer Nature B.V; Nature Portfolio
• Subjects: 704/242; 706/4066/4080; Boreholes; Closed loops; Conduction heating; Costs; Drilling; Efficiency; Electric rates; Electricity generation; Energy; Engineering; Flow velocity; Geothermal power; Heat; Heat exchange; Permeability; Power plants; Temperature; Working fluids
• ISSN: 2731-3395; 2731-3395
• DOI: 10.1038/s44172-025-00458-7

Closed-Loop Geothermal Systems (CLGS) involve connecting the injection and production wells through several borehole-sized parallel laterals instead of circulating a working fluid through a fracture network. Companies have garnered millions of dollars in investments on the claim that CLGS is truly scalable for both heating and electricity generation purposes. We show that high flow rates in the laterals lead to a steep drop in production temperatures because of a rapid cooling of the rock matrix surrounding the wells. Overcoming this physical limitation of CLGS demands an expensive task of drilling several multilaterals to reduce the lateral flow rate. Yet, simulation results indicate that, for a reservoir temperature of 180 °C, the total revenue of these systems fail to recover the lifetime costs incurred, even with 30 multilaterals and a production rate of 75 kg/s, which clearly indicates that CLGS are not scalable for solely electricity generation. Sri Kalyan Tangirala and Víctor Vilarrasa report that limited conduction heat exchange and high drilling costs result in poor economic returns for electricity generation in closed-loop geothermal systems outside high geothermal gradient fields. This questions industry claims of scalability.