Capturing CO2 from waste-fired CHP plants at low marginal cost

Capturing CO 2 from waste-fired combined heat and power (w-CHP) plants has attracted increasing attention. However, there has been no method that can guide the operation of CO 2 capture for w-CHP plants to attain economic feasibility. To bridge this knowledge gap, this paper proposes a novel method based on the marginal cost of CO 2 capture (MCoC) for the operation planning of w-CHP plants at different time scales. Two operating rules (ORs) are considered, which are based on the hourly MCoCs (OR1) and monthly MCoCs (OR2), and a real w-CHP plant is used as a case study. Results reveal that, under the electricity price of 2020 and with a carbon allowance price of 25 €/tonne, the integration of CO 2 capture decreased the net revenue by 7.3 million Euro (M€) and 5.4 M€ under OR1 and OR2, respectively, compared to the reference plant without CO 2 capture. Although OR2 could lead to a lower revenue loss, more CO 2 could be captured under OR1. Key factors affecting CO 2 capture include the electricity price, the fossil share of waste, the transport and storage cost, the price of carbon allowances, and the price of waste. Higher electricity prices can benefit the w-CHP plant under OR1, while increases in the fossil share of waste, transport and storage costs, and prices of waste decrease the plant's revenue under both ORs. To achieve net revenue from CO 2 capture, the price of carbon allowances must exceed the thresholds of 58 €/tonne and 49 €/tonne under OR1 and OR2, respectively. • The marginal cost of CO 2 capture (MCoC) is proposed to estimate the dynamic cost of CO 2 capture. • Two operating rules are developed based on the hourly MCoC and monthly MCoC for the operation of CO 2 capture. • Operating rules are tested for a waste-fired CHP plant based on real data. • The features of using MCoC based operating rules to determine the operation of CO 2 capture are investigated.