Utilizing solar energy to substitute fossil fuels or industrial waste heat as an auxiliary source for liquid CO2 energy storage (LCES) systems not only ensures a clean energy supply but also enhances solar energy accommodation and the power output of the storage system. However, existing research on solar-assisted LCES predominantly focuses on standalone power generation or combined cooling, heating, and power (CCHP) configurations, with limited attention paid to coupling with desalination processes. Furthermore, conventional strategies typically involve storing compression heat for reuse during the discharge phase, which inevitably incurs additional thermal storage costs. To address these gaps, this paper proposes a novel solar-integrated LCES system featuring a multi-generation output of cooling, heating, power, and freshwater, governed by a novel compression heat utilization strategy. Based on the principle of cascaded energy utilization, the proposed system efficiently integrates compression heat and solar thermal energy to simultaneously drive the multi-generation processes and boost the CO2 turbine inlet temperature. Under design conditions, the proposed system achieves an electric round-trip efficiency of 113.32%, an exergy efficiency of 35.88%, and an overall energy efficiency of 59.99%. Notably, the advanced MED configuration attains a heat-based gained output ratio of 7.19, significantly outperforming the 2.06 observed in traditional MED units. Sensitivity analyses reveal that increasing the CO2 turbine inlet temperature or the number of turbine stages improves the system's energy, exergy, and electrical efficiencies. While higher pump outlet pressures and compressor isentropic efficiencies enhance both exergy and electrical efficiencies, they result in a decline in overall energy efficiency. Furthermore, reducing feed seawater salinity or increasing outlet brine salinity optimizes the thermodynamic performance of both the MED unit and the integrated system. These findings provide valuable theoretical insights and technical guidance for the development and performance optimization of solar-coupled LCES systems.
Design and thermodynamic analysis of a multi-generation solar-assisted liquid carbon dioxide energy storage system with a new compression heat utilization method
Desideri U.
2026-01-01
Abstract
Utilizing solar energy to substitute fossil fuels or industrial waste heat as an auxiliary source for liquid CO2 energy storage (LCES) systems not only ensures a clean energy supply but also enhances solar energy accommodation and the power output of the storage system. However, existing research on solar-assisted LCES predominantly focuses on standalone power generation or combined cooling, heating, and power (CCHP) configurations, with limited attention paid to coupling with desalination processes. Furthermore, conventional strategies typically involve storing compression heat for reuse during the discharge phase, which inevitably incurs additional thermal storage costs. To address these gaps, this paper proposes a novel solar-integrated LCES system featuring a multi-generation output of cooling, heating, power, and freshwater, governed by a novel compression heat utilization strategy. Based on the principle of cascaded energy utilization, the proposed system efficiently integrates compression heat and solar thermal energy to simultaneously drive the multi-generation processes and boost the CO2 turbine inlet temperature. Under design conditions, the proposed system achieves an electric round-trip efficiency of 113.32%, an exergy efficiency of 35.88%, and an overall energy efficiency of 59.99%. Notably, the advanced MED configuration attains a heat-based gained output ratio of 7.19, significantly outperforming the 2.06 observed in traditional MED units. Sensitivity analyses reveal that increasing the CO2 turbine inlet temperature or the number of turbine stages improves the system's energy, exergy, and electrical efficiencies. While higher pump outlet pressures and compressor isentropic efficiencies enhance both exergy and electrical efficiencies, they result in a decline in overall energy efficiency. Furthermore, reducing feed seawater salinity or increasing outlet brine salinity optimizes the thermodynamic performance of both the MED unit and the integrated system. These findings provide valuable theoretical insights and technical guidance for the development and performance optimization of solar-coupled LCES systems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
