A solar-assisted metal oxide redox system for peak-load shifting in coal-fired power plants

摘要

This study is concerned with a solar-assisted metal oxide redox system integrated with a 500 MWe coal-fired power plant for peak-load shifting applications. The integrated system is a thermochemical energy storage system which stores energy from both the excess electricity and solar irradiance during off-peak hours and recover them during peak hours. The analysis was conducted using the simulation packages Aspen Plus v8.8 and with Co_3O_4/CoO as the metal oxides. The results demonstrate that such energy storage system can achieve an energy storage density of 821 kJ/kg and an optimum round-trip efficiency of 32-46% depending on whether waste heat recovery is implemented. In addition, a dynamic-state case study was conducted for the integrated system operating under the demand profile of a typical Australian summer day. Its preliminary design parameters and operating performances were determined. It was confirmed that the peak electricity demand can be fully met by the energy stored from the off-peak surplus electricity and solar heat, which accounts for 92% and 8% of the total energy input, respectively. The load shifting achieved by the integrated system offers the coal-fired power plant a great flexibility in meeting varied electricity demands.