Comparative study of two discharge architectures for a multi-energy pumped thermal energy storage system using finite dimension thermodynamics

This study compares two discharge architectures for multi-energy pumped thermal energy storage systems. In the first architecture, all stored energy is supplied to the power block, which produces both electricity and useful heat. In the second architecture, part of the stored energy is directly recovered through heat exchangers to supply heat, while the remainder is used by the power block, which rejects heat to the external environment. The performance of both configurations was analyzed using finite dimension thermodynamics, considering key indicators such as power block efficiency, total required power, and heat exchanger conductances. This study is conducted within the context of a mining industrial facility located in northern Canada. The results show that the second architecture is more efficient when the external environment temperature is lower than the useful heat sink temperature. For given external environment and useful heat sink temperatures, the viability of each configuration mainly depends on the required powers and the storage temperature. When the system delivers the maximum required powers (12.58 MW of electrical power and 8.99 MW of useful heat), architecture A2 is more advantageous for storage temperatures below 372 °C.