Techno-economic assessment of alternative fuels in second-generation carbon capture and storage processes

Several technical methods are currently discussed to meet the objectives of the United Nations Framework Convention on Climate Change 21st Conference of the Parties, Paris, France (Paris Agreement) in terms of carbon dioxide (CO2) concentration in the Earth's atmosphere. In addition to efficiency improvements, reduction of energy consumption, and the utilization of renewable energy sources, the application of carbon capture and storage (CCS) technologies seems to be unavoidable. Whereas all these measures aim on the reduction of CO2 that is being newly released, there is the approach to remove CO2 from the atmosphere that has already been emitted. This can be achieved by the utilization of bioenergy in CCS processes. Within this paper, the utilization of alternative fuels in two second-generation CCS processes is assessed. In this regard, chemical looping combustion (CLC) and calcium looping (CaL) are two promising technologies. Both processes have proven their feasibility already in semi-industrial scale. The assessment includes three different types of fuel namely coal, biomass, and solid recovered fuel (SRF). The analysis is twofold: first, a heat and mass balance calculation reveals the specific CO2 emissions of each power system; second, a cost analysis points out the feasibility from an economic point of view. The highest CO2 removal can be achieved by a biomass-fired CLC unit (- 696 g(CO2)/kWh(e)). Furthermore, it was found that the co-combustion of SRF even at moderate co-firing rates allows for noteworthy improved economics of the CCS system. Therefore, the utilization of waste-derived fuels in the context of CCS processes should be put more into focus in future research activities.