Dynamics of Thermal Energy Storage in Integrated Energy Systems With On-Site Power Generation

Integrated energy systems (IES) incorporating on-site power generation provide opportunities for improving reliability in energy supply, maximizing fuel efficiency, and enhancing environmental quality. To fully realize these attributes, optimum design and dynamic performance of integrated systems for a given application have to be pursued. Whether referred to as cogeneration, combined heat and power (CHP) or building cooling, heating, and power (BCHP), integrated energy systems manifest effective energy management aimed at closing spatial and temporal gaps between demand and supply of electrical and thermal energy. This is accomplished by on-site power production and utilization of the resulting thermal energy availability for thermally-driven technologies including desiccant dehumidification, absorption cooling, and space heating. The notion that the demands for thermal and electrical energy are not always congruent and in phase signifies the importance of considering thermal energy storage (TES) for integration. This paper explores the potential impact of implementing TES technology on the overall performance of integrated energy systems from the first- and second-law perspectives. In doing so, the dynamics of packed bed thermal energy storage systems for potential energy recovery from the exhaust gas of microturbines are investigated. Using a validated simulation model, the transient thermal response of these TES systems is examined via parametric analyses that allow variation in the thermal energy availability and physical characteristics of the packed beds. The parasitic electrical energy requirement associated with the pressure losses in the packed beds is included in the performance assessment. The results of this study are indicative of the promising role of TES in integrated energy systems.