Greenhouse Gas Emission Analysis of Biomass Moving-bed Pyrolytic Polygeneration Systems based on Aspen Plus and Hybrid LCA in China

Abstract

Under the existing scenario of greenhouse gas (GHG) emission reduction technologies, it is difficult to make the global temperature rise within 2°C in 2100. Thus, bio-energy with carbon capture and storage (BECCS) technology, as one of primary negative carbon emission methods, is urgent to deploy. In order to correctly recognize the development potential of bio-energy, the biomass pyrolytic polygeneration system, as the second novel bio-energy technology, should be carefully investigated in terms of GHG emission intensity and GHG emission reduction firstly. In this study, the material and energy flow in the process was carefully studied, and its environmental benefits was further researched. Based on the biomass pyrolysis mechanism and components pyrolysis property, the model of biomass pyrolytic polygeneration system was built on the Aspen Plus simulator, which is used to make an analysis of the life cycle greenhouse gas emission reduction. Results indicated that the agriculture process as the largest contributor to total GHG emissions with 86.03% of the total plant GHG emissions. In the entire pyrolysis temperature range, the intensity of GHG emissions from moving bed pyrolytic polygeneration system is from 4.15 to 6.12 g CO2-eq/MJ. Compared with other pyrolysis products, bio-char has a greater impact on the GHG emission reduction benefits of pyrolytic system. For the same system capacity, the system has the largest emissions reduction at a reaction temperature of 250°C, where also the bio-char yields is largest. If all of the bio-char returns to the field, the system can lead to negative carbon emission, which is 22 times larger than the system GHG emission when pyrolysis temperature is 250°C.