Scientists from Southeastern University in China they were investigating the possibility of a connection compressed carbon dioxide (CO2) with a combined heat and power (CHP) unit for storing solar and renewable energy. The proposed solution is a closed-cycle system with a 600 MW cogeneration unit and a carbon dioxide energy storage (CCES) device. It uses heat from the return water of the heating network and operates in two stages of compression and expansion using water and carbon dioxide as working fluids, without mass exchange with the external environment. “During off-peak periods, the s-CO2 released from the low-pressure tank (LPT) is compressed in a compressor driven by the excess cogeneration production capacity,” the researchers explained. The compressed CO2 then passes through an intercooler to store the heat of compression in the water leaving the cold water tank (CWT). “After two stages of compression, the s-CO2 is stored in a high-pressure tank (HPT) and the cooling water is compressed by a pump to be stored in a hot water tank (HWT),” the researchers said. “The cooling water in the improved system absorbs additional heat from the intermediate extraction steam before entering the HWT.”

(Emiliano Bellini)