Assessment and optimization of a novel combined heat and power system through an energy nexus approach: Enhancing energy storage and sustainability

Traditional energy systems often suffer from significant energy losses and environmental impacts, highlighting the urgency for advanced technologies that can effectively harness and utilize waste heat while integrating renewable sources. This paper presents a novel hybrid combined heat and power system, termed solid oxide fuel cells (SOFC), supercritical CO2 power cycle (SCO2) and Brayton pumped thermal electricity storage (PTES). The high-temperature exhaust gas is utilized to heat CO2 within the SCO2 power cycle, enabling a secondary energy recovery. To fully capitalize on waste heat and minimize environmental impacts, a Brayton PTES system is integrated, storing residual heat for low-cost power supply during non-operational periods. The exhaust gas from the SOFC enhances the heating of the fuel, maximizing energy utilization and contributing to energy conservation. An innovative energy nexus assessment integrating energy, exergy, exergoeconomic, exergoenvironment, emergoeconomic, and emergoenvironment designed to analyze and optimize the comprehensive performance of the proposed system. The comprehensive optimization results of the system show that when the fuel flow rate is 0.42 mol/s and the steam carbon ratio is 1.5, the energy efficiency is 70.47 % and the effective energy efficiency is 43.89 %. Compared to its initial state, the exergy efficiency and energy efficiency of the system have increased by 2.05 % and 5.1 %, respectively.