Thermoeconomic Analysis of Subcritical and Supercritical Isobutane Cycles for Geothermal Power Generation

Andrea Arbula Blecich and Paolo Blecich ()
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Andrea Arbula Blecich: Faculty of Economics and Business, University of Rijeka, 51000 Rijeka, Croatia
Paolo Blecich: Faculty of Engineering, University of Rijeka, 51000 Rijeka, Croatia

Sustainability, 2023, vol. 15, issue 11, 1-25

Abstract: This article presents a novel and comprehensive approach for the thermoeconomic evaluation of subcritical and supercritical isobutane cycles for geothermal temperatures of T geo = 100–200 °C. The isobutane cycles are optimized with respect to the maximum net power or minimum levelized cost of electricity (LCOE). Cycle optimization is also included, using a minimum superheat temperature to avoid turbine erosion, which is usually neglected in the literature. The results show that economic optimums are found in the far superheated region, while thermal optimums are obtained with dry saturated or with slightly superheated vapor at the turbine inlet (Δ T sup < 5 °C). Supercritical cycles achieve better thermal performance than subcritical cycles for T geo = 179–200 °C. Internal heat recuperation improves the cycle performance: the net power output increases and the LCOE decreases, but specific installation costs (SICs) increase due to the additional heat exchanger. For geothermal temperatures of T geo = 120 → 150 °C, the costs are LCOE = 100 → 80 USD 2022 /MWh and SIC = 7000 → 5250 USD 2022 /kW, while for geothermal temperatures of T geo = 150 → 200 °C, the estimated costs are LCOE = 80 → 70 USD 2022 /MWh and SIC = 5250 → 4600 USD 2022 /kW.

Keywords: geothermal power plant; thermoeconomic analysis; levelized cost of electricity; specific installation costs; binary cycle optimization (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
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