Although not yet a mature technology, biomass energy with carbon capture and storage (BECCS) is expected to be the leading negative emissions technology deployed over the 21st century to reduce greenhouse gas (GHG) emissions. In this paper, a novel BECCS cycle using exhaust gas recycling (EGR)-enhanced biomass gasification is described and analysed. This cycle combines an atmospheric gasifier and an Otto cycle engine operating under an oxy-gasification/combustion CCS scheme. Exhaust gasses from the Otto cycle, rich in CO2 and at high temperature, are recycled to the gasifier to enhance syngas production. Analysis of a representative numerical model illustrates how EGR creates higher system efficiency and lower specific CO2 emissions while allowing for lower gasifier O2 equivalence ratios (E/R). Compared to a similar power cycle without EGR, the proposed cycle improved system efficiency from 21.7% to 28.8% while reducing specific CO2 emissions from the cycle by 25%.
Keywords Biomass gasification, BECCS, CO2 gasification, Integrated gasification power cycle, Negative emissions