A thorough investigation of the impacts of trigeneration-CAES off-design operation on its thermodynamics, economic and environmental effectiveness

In the category of novel energy storage systems emerging every day, a trigeneration compressed air energy storage system has received special attention. The main reasons for this are the very high overall performance efficiency it offers and the fact that this energy storage system tri-generates heating, cooling, and electricity, facilitating different energy sectors integration. This study investigates the effect of the partial-load operation of this technology on its exergetic, energetic, economic, and environmental effectiveness, considering the changes in all the important parameters such as the efficiency of the components, pressure ratios, flow rates, etc. The simulations are carried out based on the standard energy price and regulations of Denmark as a case study. The results show that the off-design operation causes a sharp collapse in its technical and economic performance metrics. For example, if a load of operation drops from 100% to an average level of 70% over a year, not only the average energy and exergy efficiencies will drop significantly, the payback period of the system would drop from 11 years to over 25 years. Similarly, the environmental benefit of the system in such conditions would decrease from about 11,000 to below 7000 tonnes of equivalent CO₂ emission reduction.