Carbon reduction and flexibility enhancement of the CHP-based cascade heating system with integrated electric heat pump

The energy utilization efficiency and the flexibility enhancement of the combined heat and power (CHP) plant can promote both decarbonization and renewable energy integration. In this research, we proposed a novel CHP cascade heating system by integrating it with the electric heat pump (EHP). The integration of EHP can consume power generation load and bear part of the heat load, which improves the flexible peak regulation ability of the novel heating system. Based on the detailed simulation model of a typical 2 x 300 MW subcritical CHP plant, the reference and novel systems are compared in thermodynamic and peak-load regulation performance to present the benefits of the EHP design. The results showed that, under the design condition, the heating capacity in the novel system had an increment of 6.02 % to that in the reference system, bringing out a 4.51 % improvement in electricity generation efficiency. Correspondingly, the average standard coal consumption rate for generating of the novel system reduced by 9.53 g/kWh. Under the same heat load, the peak shaving lower limit of the novel system is 59 MW lower than the reference system on average, and the load rate is reduced by 10 % of the rated power generation capacity on average. In the case study, under the typical day operation of the regional electric -thermal integrated energy system, the wind power curtailment ratio of the novel system is 10.75 % lower than that of the reference system. Meanwhile, with further waste heat recovery, the daily standard coal consumption of the novel system can be saved by 231.81 t, equivalent to a reduction of 607.34 t of CO2 emissions.