A thermal battery assisted by proton exchange membrane fuel cell waste heat for coordinated heat and power supply in green industrial parks

Low-temperature proton exchange membrane fuel cell waste-heat recovery is generally investigated through separate heat-supply, heat-pump, storage, or power-recovery routes, leaving the potential of a shared thermal inventory for time-shifted heat–power coordination insufficiently addressed. This study proposes a waste-heat-assisted, multi-output thermal battery for green industrial parks. Under baseline conditions, a 1 MW proton exchange membrane fuel cell with an electrical efficiency of 0.50 yields 850 kW of recoverable liquid-cooling waste heat at 60–65 °C while continuously supplying electricity. The system couples a heat-pump charging cycle with two-tank thermal-oil storage and parallel organic Rankine cycle and direct-steam discharge branches, enabling stored heat to be allocated between additional electricity and saturated process steam. Working-fluid screening combines thermodynamic performance with operating pressure, toxicity, flammability, and regulatory constraints. Although toluene and benzene maximize heat-pump coefficient of performance and organic Rankine cycle efficiency, respectively, cyclopentane provides a balanced engineering compromise and is adopted for the integrated analysis. As the hot-tank temperature increases from 160 to 200 °C, the heat-pump coefficient of performance decreases from 2.730 to 2.114, whereas the energy stored during two hours of charging increases from 2.575 to 3.097 MWh th ; the electricity generated by the organic Rankine cycle during a full-tank discharge simultaneously increases from 247.5 to 370.0 kWh. For the representative 180 °C design supplying 135 °C saturated steam with an organic Rankine cycle oil-flow fraction of 0.5, the thermal-battery-pathway exergy efficiency is 21.325 %; park-level net electricity supply is 0.384 MW during charging and 1.075 MW during discharging, accompanied by 0.294 MW th of steam heat. Over the rated four-hour cycle, net electricity and steam-heat supplies are 2.919 MWh e and 0.588 MWh th , respectively. The thermal battery therefore does not primarily deliver a net increase in cycle electricity; its central value is upgrading low-grade proton exchange membrane fuel cell waste heat and enabling time-decoupled, flexible allocation of heat and electricity through a shared thermal inventory.