Process Modeling and Optimization of Supercritical Carbon Dioxide-Enhanced Geothermal Systems in Poland

Abstract This paper presents a comprehensive analysis of supercritical carbon dioxide (sCO2)-enhanced geothermal systems (EGSs) in Poland, focusing on their energetic performance through process modeling and optimization. EGSs harness the potential of geothermal energy by utilizing supercritical carbon dioxide as the working fluid, offering promising avenues for sustainable power generation. This study investigates two distinct configurations of sCO2-EGS: one dedicated to power generation via a binary system with an organic Rankine cycle and the other for combined power and heat production through a direct sCO2 cycle. Through accurate process modeling and simulation, key parameters influencing system efficiency and performance are identified and optimized. The analysis integrates thermodynamic principles with geological and operational constraints specific to the Polish context. The results highlight the potential of sCO2-EGSs to contribute to the country’s energy transition, offering insights into the optimal design and operation of such systems for maximizing both power and thermal output while ensuring economic viability and environmental sustainability.Process Modeling and Optimization of Supercritical Carbon Dioxide-Enhanced Geothermal Systems in PolandpublishedVersio

New and accurate thermodynamic property data of CO2-EGS relevant working fluids with data

The article presents a new setup for the accurate measurements of the phase behaviour of CO2 mixtures relevant to CCS as well as a CO2-H2O working fluid for EGS, designed to cover the temperature range from -60 to 200 °C and up to 100 MPa in pressure. Included in the article are a description of the experimental setup, methodology, and results of the experimental campaign conducted in the SINTEF Energy Research labs for the EnerGizerS project. Phase equilibrium of the CO2-water system has been investigated at the temperature of 50 °C and pressures between 1 and 17.5 MPa, using the analytical isothermal technique. These measurements are compared and verified against the existing data, followed by a presentation of the fit of GERG-2008/EOS-CG for CO2 and H2O. The maximum mole fraction of water in the CO2[sbnd]H2O mixture at measured conditions should not exceed 0.35 % and even less than 0.3481 % at 7.8 MPa to maintain the vapour phase of the mixture. The accuracy with respect to GERG-2008/EOS-CG varies from 1.044 % to 10.683 % near the critical values of sCO2. The estimated uncertainty of the setup is 31 mK for temperature measurements, from 0.4 to 2.5 kPa for pressure measurements and from 0.2 to 2.1 % of total combined relative uncertainty as regards the mole fraction. Despite the fact that the EGS reservoir could reach conditions above 150 °C and 50 MPa, lower values were adopted to validate the setup at 50 °C. Knowledge gaps at higher pressure and temperature values are still in dire need of filling. © 2024New and accurate thermodynamic property data of CO2-EGS relevant working fluids with datapublishedVersio

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 energyTechno-Economic Assessment of the Supercritical Carbon Dioxide Enhanced Geothermal SystemspublishedVersio