Techno-Economic Assessment of the Supercritical Carbon Dioxide Enhanced Geothermal Systems

Enhanced geothermal systems distinguish themselves among other technologies that utilize renewable energy sources by their possibility of the partial sequestration of carbon dioxide (CO₂). Thus, CO₂ in its supercritical form in such units may be considered as better working fluid for heat transfer than conventionally used water. The main goal of the study was to perform the techno-economic analysis of different configurations of supercritical carbon dioxide-enhanced geothermal systems (sCO2-EGSs). The energy performance as well as economic evaluation including heat and power generation, capital and operational expenditures, and levelized cost of electricity and heat were investigated based on the results of mathematical modeling and process simulations. The results indicated that sCO2 mass flow rates and injection temperature have a significant impact on energetic results and also cost estimation. In relation to financial assessment, the highest levelized cost of electricity was obtained for the indirect sCO2 cycle (219.5 EUR/MWh) mainly due to the lower electricity production (in comparison with systems using Organic Rankine Cycle) and high investment costs. Both energy and economic assessments in this study provide a systematic approach to compare the sCO2-EGS variants.
Keywords: enhanced geothermal systems; CO₂-EGS; supercritical carbon dioxide cycles; Organic Rankine Cycle; combined heat and power; geothermal energy