State-of-Charge (SoC) Management of PTES Coupled Industrial Cogeneration Systems

We present a novel optimization-based state-of-charge (SoC) management solution for pumped-thermal energy storage (PTES) systems capable of charging and discharging with electrical power and discharging high temperature heat – for integration with industrial processes. The considered PTES system in the study uses a supercritical CO2 recuperative Brayton cycle (SCBC) utilizing molten salt and water as hot and cold storage materials respectively. A SoC balancing heat exchanger is integrated along with a utility heat exchanger to the base design to accommodate withdrawal of high temperature heat. The study builds on a detailed part-load study to extract the SoC dynamics as a function of the electrical power as well as the heat withdrawal rate. These functions are used for modelling SoC management as an optimization problem considering three case studies; a base case for only electrical operation given an electricity price profile, a flexible operation study with electrical and heat price profiles, and a continuous heat supply case where the system delivers heat to a process. The results indicate that the proposed approach can enable optimized operation while respecting SoC constraints under different scenarios and illustrate the potential for the integration of PTES systems with industrial processes for the decarbonization of heat provision.