Ensuring Baseload Power Delivery by Complementing Two Independent Energy Sources: Solar Energy and Wellbore Closed-Loop Thermal Energy

Summary For this study, we explored solutions to revive inactive wells for power generation. Accordingly, in this article, we show a method that involves circulating an efficient heat-preserving refrigerant down the well’s annulus and up through the tubing in actual field settings. This closed-loop process generates steam or hot water at the wellhead, enabling power production independent of the usual geothermal source. Among the working fluids analyzed, R-134a and R-1234yf refrigerants demonstrated superior performance over a 20-year production period compared with pentane and water. The method combines closed-loop fluid circulation to harness thermal heat at night with solar energy generation during the day for electricity production. Together, these two energy sources provide a reliable baseload power supply, addressing the intermittent nature of solar energy while extending the productive use of geothermal resources. In this system, geothermal and solar energy are used independently but complement each other to ensure continuous power delivery. At night, thermal energy generates electricity via a closed-loop system that circulates a working fluid through the wellbore, extracting heat from the surrounding formation. During the day, solar energy supplies electricity, reducing reliance on thermal resources and enabling heat recovery for subsequent nighttime operations. The geothermal wells in the studied area contain many noncondensable gases produced in the geothermal brine, ranging from 0.5% to 3% mass content. The proposed method is noncondensable gases-free and environmentally friendly. In addition, geothermal power plants exhibit higher efficiency during the nighttime due to the enhanced performance of the cooling system under nocturnal conditions. Key metrics, including net present value (NPV) and levelized cost of energy (LCOE), support the economic viability of this method. Specifically, four field examples from two geothermal fields provide the overall value proposition. We applied the hybrid thermal/solar approach to various well depths and geothermal gradient conditions and found that it produces between 52 MWh and 138 MWh of electricity per well over a 20-year period, which is sufficient to power 226–730 homes in Türkiye.