Flexible operation of post-combustion CO2 capture in district heating–coupled waste-to-energy plants

Waste-to-energy plants can recover a large share of the heat released during municipal waste incineration and supply it to nearby consumers through district heating networks, thereby improving overall energy utilization. However, when post-combustion carbon capture is integrated into such district heating-coupled systems, operation is constrained by steam availability, electricity market conditions, and plant integration limits. This study develops a two-layer modeling framework to evaluate the flexible operation of a monoethanolamine-based CO 2 capture system integrated into a waste-to-energy plant supplying district heating. First, a quasi-steady-state process model is used to derive feasible operating envelopes linking steam extraction, electricity generation, and CO 2 capture. These relationships are then embedded in a year-scale mixed-integer linear programming model to determine cost-optimal hourly operation under different electricity tariff structures and flexibility options, including photovoltaic generation and battery storage. The results show that electricity tariff design strongly affects both operational economics and annual capture performance. Dynamic electricity tariffs enable more flexible operation of the capture unit during low-price periods, increasing the annual realized capture ratio compared with fixed tariffs. Additional flexibility from photovoltaic generation and battery storage further improves system performance. In the case study, using the district-heating-priority control strategy under fixed-tariff operation and without additional flexibility as the reference case, dynamic-tariff operation increased the annual realized capture ratio by about 6 percentage points, while the combined PV–battery configuration increased it by about 10 percentage points.