Design and performance evaluation of a shared energy storage system integrated within combined heat and power plants in an energy network

The green power curtailments in energy networks are serious due to the increasing penetration of green power and the inflexibility of combined heat and power (CHP) plants. CHP plants integrated with shared energy storage systems (CHP-SES) are feasible to reduce distributed green power curtailments while meeting power and heat demands due to their potential to increase the dispatchable range and load response rate of the energy network. However, the system design and thermo-economic assessment of CHP-SES have not been systemically studied. Therefore, this paper proposes two CHP-SES design modes involving shared electrical energy storage and shared thermal energy storage, including three system configurations to store distributed green power curtailments during charging processes and convert them to available power or heat during discharging processes. Then, the exergy and economic analysis models are developed to reveal the thermo-economic feasibilities of the proposed modes. Besides, the design procedures of charging-discharging cycles and the impacts of key parameters on the thermo-economic performance of proposed modes are determined. Results show that the proposed three CHP-SES configurations can achieve the effective reuse of distributed green power curtailments, with round-trip exergy efficiencies of 78.98 %, 54.34 %, and 43.36 %, respectively. They are also economically feasible, with additional daily profits of 2096 USD, 5617 USD, and 5152 USD, respectively.