Assessment evaluation of a trigeneration system incorporated with an underwater compressed air energy storage

This paper is aiming at stably satisfying the diverse energy requirement of users by using intermittent renewable energies. A novel trigeneration system incorporating with an eco-friendly high temperature underwater compressed air energy storage and an ejector refrigeration cycle is thus developed and analyzed. The mathematical model for the system is established and verified by comparing with the data in open literature. A series of energy and exergy analyses are carried out to find both the qualitative and quantitative links between key properties and the system performance indicators. Results demonstrate that the unit increase of the storage pressure improves significantly the heating energy and net power (27.73 kW and 35.53 kW) while has a positive influence on cooling energy. The cooling energy and net power generation increase as the turbine inlet temperature increases. An increase in temperature has no impact on the heat produced for the end-user. The ambient temperature has positive, negative, and negligible effects on the heating, cooling energy, and the net power, in respective. Aiming to find the best performance of the system, a multi-objective optimization study is conducted to a maximal overall exergy efficiency but minimal capital cost for the novel trigeneration system. The optimized design can produce 55.85% overall exergy efficiency with $296,288 capital investment cost.