CO₂ capture costs of chemical looping combustion of biomass: A comparison of natural and synthetic oxygen carrier

Abstract

Chemical looping combustion has the potential to be an efficient and low-cost technology capable of con-tributing to the reduction of the atmospheric concentration of CO2 in order to reach the 1.5/2 C goal and mitigate climate change. In this process, a metal oxide is used as oxygen carrier in a dual fluidized bed to generate clean CO2 via combustion of biomass. Most commonly, natural ores or synthetic materials are used as oxygen carrier whereas both must meet special requirements for the conversion of solid fuels. Synthetic oxygen carriers are characterized by higher reactivity at the expense of higher costs versus the lower-cost natural ores. To determine the viability of both possibilities, a techno-economic compar-ison of a synthetic material based on manganese, iron, and copper to the natural ore ilmenite was con-ducted. The synthetic oxygen carrier was characterized and tested in a pilot plant, where high combustion efficiencies up to 98.4% and carbon capture rates up to 98.5% were reached. The techno-economic assessment resulted in CO2 capture costs of 75 and 40 €/tCO2 for the synthetic and natural ore route respectively, whereas a sensitivity analysis showed the high impact of production costs and attrition rates of the synthetic material. The synthetic oxygen carrier could break even with the natural ore in case of lower production costs and attrition rates, which could be reached by adapting the produc-tion process and recycling material. By comparison to state-of-the-art technologies, it is demonstrated that both routes are viable and the capture cost of CO2 could be reduced by implementing the chemical looping combustion technology.