Energy, exergy, and exergo-economic analysis of a novel combined power system using the cold energy of liquified natural gas (LNG)

This study proposed a novel combined power system that uses the cold energy of liquefied natural gas (LNG) for the BOTAS LNG receiving terminal located in Marmara Eregli in Turkey. In the proposed system, the main cycle was a Brayton cycle (BC), while the subcycles consisted of a supercritical CO2 cycle (S-CO2) and an organic Rankine cycle (ORC). The combined power system was analyzed based on energy, exergy, and exergo-economic. The effects of the determined decision variables (Compressor-II input temperature, Compressor-I-II and Turbine-I-III isentropic efficiencies, CO2 cycle pressure rate, Turbine-III input pressure, ORC pressure rate, and propane mass flow rate) on the exergo-economic performance of the system were discussed, and the optimal points of the system were found. The base state of the system that had operational conditions and assumed design inputs was compared to the working conditions that were determined as a result of optimization, and a cost reduction of 67% was calculated.