Exergy-economic analysis and multi-objective optimization of a multi-generation system based on efficient waste heat recovery of combined wind turbine and compressed CO2 energy storage system

Abstract

Due to the intermittent feature of renewable energies, their combination with energy storage systems seems efficient and profitable. In this regard, a wind turbine system is coupled with a compressed CO2 energy storage (CCES) system for multi-generation propose. This combination has not been done yet and seems very attractive and efficient with the present popularity of wind energy and energy storage systems. A fraction of the output power of the wind turbine is sent to the compressor and electric heater of the CCES layout in the charging and discharging period. In the CCES system, a thermoelectric generator (TEG 1), an absorption chiller, and a domestic hot water heat exchanger are used to waste energy elimination and the waste energy of the wind turbine is recovered by a trilateral cycle (TLC). The produced power of the TEG 1 and TLC is transmitted to a reverse osmosis desalination unit and an alkaline electrolyzer for freshwater and hydrogen production. Hence, the considered system is converted to a multi-product one. Energy, exergy, and exergy-economic (3E) studies are done on the whole layout through parametric analysis and multi-objective optimization. Exergy round trip efficiency and unit cost of products are obtained as 37.027% and 30.41 $/GJ in the optimization process. The considered system can produce 1960 kW of power, 336.1 kW of heating, 183.3 kW of cooling, 1.077 kg/s of freshwater, and 0.0138 kg/h of hydrogen in this case.