Energetic, exergetic, and carbon footprint performance assessment of a combined renewable simple and recompressed Brayton S-CO2/ORC system

The energetic, exergetic, and environmental performance of a Brayton cycle is improved through ORC bottoming cycle in order to achieve thermo sustainability operational conditions. The proposed models for Brayton S-CO 2 /ORC systems using a concentrated solar power as energy source are based on energy and exergy balances, and the environmental impact assessment is conducted through a life cycle analysis, allowed the objective to develop a parametric study involving the net power, the thermal and exergy efficiency, the exergy destruction of each component and the environmental impact of the combined system, as a function of the variation of the inlet temperature of Turbine 1 (T1), the compression ratio and the thermodynamic efficiency of the turbines and compressors, which are relevant energy and environmental performance parameters for both cycles studied. For the evaluated conditions, the Brayton SRC-CO 2 -ORC cycle using steel as construction material, shows better energetic, exergetic, and environmental results, generating a net power 42% higher than the Brayton S-CO 2 -ORC cycle at the base conditions of the study, and when increasing the temperature (T1) up to 650 °C where it obtains the maximum value of second law exergetic efficiency with 24.58%, while the cycle without recompression registers an efficiency of 19.45%. For both systems the device with the greatest potential improvement and environmental impact is the concentrated solar thermal power (CSP) system, which represents a 60% of the total exergy destroyed and 87% of the total environmental impact of both systems, while the construction phase in both systems represents 95.38% of the environmental impact, while decommissioning, maintenance and operation represent 4.52% for the materials evaluated.