Carbon-Neutral Polygeneration in Waste-to-Energy Plants: Techno-Economic Study Using Carbon Capture and Utilization

Abstract

Waste-to-energy (WtE) plants play a key role in waste management worldwide by providing a solution for the waste disposal, generating electric power, and supplying heat for district heating and industrial processes. Efficient CO2 capture solutions are required to abate the CO2 emissions from WtE facilities. Nevertheless, most capture processes entail high economic penalties. In this work, we introduce two highly integrated concepts for avoiding CO2 emissions. One concept uses carbon capture and storage (CCS), while the other consists of carbon capture, storage, and utilization (CCUS). CO2 capture is performed using a carbonate looping (CaL) process and utilization involves direct methanol synthesis. The CCUS concepts are analyzed for retrofitting a German WtE plant, which treats 200 kt of waste per year. We perform a techno-economic assessment that includes process modeling using the software Aspen Plus. The results show that the retrofitting concepts with polygeneration have the potential to reduce CO2 emissions in a cost-efficient manner. The solutions can be retrofitted with lower footprint than other capture technologies due to the combustion of pretreated waste in the capture unit. The cost of CO2 transport and storage is a main driver for the project costs. Producing methanol from captured CO2 and H2 is only feasible in scenarios with very low electricity costs (< 25 €/MWh). In other scenarios, it is more profitable to transport and store CO2 in geological sites (CCS). The avoidance costs of the CCS concept, including transport and storage, are approximately 65 €/tCO2,av, making it competitive with the current price of CO2 certificates in the European Union.

Keywords: polygeneration, methanol from CO2, e-methanol, waste-to-energy, techno-economic analysis, carbonate looping, carbon capture and utilization (CCU)