Valorizing Waste Derived Fuels for Climate Change Mitigation: Techno-Economic Comparison of CCS and CCU Approaches based on the Carbonate Looping Process

Abstract

It is common understanding that a reduction of anthropogenic CO2 emissions is undispensible. Furthermore, already emitted CO2 has to be removed from the atmosphere. To meet these objectives, novel processes must be developed and applied. Besides the utilization of renewable energy sources and a reduction of energy intensity, the application of carbon capture and storage/utilization (CCS/U) technologies is required. In a waste-to-energy (WtE) plant, the carbon contained in the waste is largely converted to CO2 and released to the environment. Thereby, heat and power are produced as valuable by-products of waste treatment. The carbon is partly of biogenic origin (e.g. wood and food waste) and of fossil origin (e.g. plastics derived from mineral oil). By separation, storage or utilization of the CO2 contained in the WtE plant flue gas, municipal solid waste (MSW) is utilized as a resource for clean energy and net negative CO2 emissions. The carbonate looping (CaL) process represents an efficient option for post-combustion CO2 capture from WtE plants. In this process, the heat for sorbent regeneration can be supplied by solid recovered fuels (SRF), which are sourced of pretreated MSW. Based on the results of experimental investigations in an SRF-fueled CaL pilot plant at 1 MWth scale, this study focuses on the techno-economic assessment and comparison of two valorization pathways for captured CO2, namely i) long term storage and ii) utilization to produce methanol. Key performance indicators (KPI) of the process chain, such as production costs of methanol and levelized costs of electricity (LCOE) are calculated and compared. Based on a steady-state process model for the CaL process, investment costs are determined according to a bottom-up approach for each component. Operational costs are derived from relevant material and product streams. The economic analysis takes various investment and operation scenarios into account to assess techno-economic characteristics in light of the future energy market. Factors such as negative emissions credits, low electricity cost, increased gate fees or plant size are considered.