Energy and exergy analyses of a solar-based multi-generation energy plant integrated with heat recovery and thermal energy storage systems

Abstract

By the depletion of natural resources, the utilization of solar energy to provide the required needs of societies attracted many researchers across the globe. An innovative multigeneration energy system driven by solar energy is proposed in this paper. The proposed system utilizes a pressurized cavity-based solar power tower and latent thermal energy storage (TES) to continuously harness the solar energy. Considering the high-temperature nature of solar tower technology, a four-step Copper-Chlorine (Cu-Cl) thermochemical cycle is used to produce hydrogen, oxygen, and steam. Using an unfired gas turbine unit, air is used as the heat transfer fluid of the solar tower unit, instead of molten salt, to supply the required heat for the thermolysis and hydrolysis reactions of the Cu-Cl cycle. Therefore, the deficiencies of molten salts are eliminated. Moreover, recovering heat within the integrated system improves the performance of the system significantly. Also, By utilization of a high-temperature ternary eutectic phase change material (PCM), a dynamic model is developed to deal with the intermittency of solar energy. Using energy and exergy approaches, the proposed system is investigated to assess exergy destruction rates and the overall system performance. A parametric study is performed to investigate the influence of design parameters such as the number of heliostats, pressure ratio of GT, and temperatures of reactions on the system performance. The results show that the system produces electricity, steam, hydrogen, and oxygen at a rate of 41.9 MW, 12.6 kg/s, 0.19 kg/s, and 0.76 kg/s, respectively. Energy and exergy efficiencies of the integrated system are found to be 49.9%, and 44.9%, respectively. The proposed system is compared with other alternative systems available in the literature and shows the best performance among others.