Integrated Production Technology And Life Cycle Assessment Of Bioethanol From Whole Plant Cassava

Bioethanol is an important renewable energy source.It can be used as the vehicle liquid fuel and plays a different role from renewable energy sources such as wind and solar energy.The production of ethanol from cassava and other crops carries the risk of land use.The production of ethanol from lignocellulose such as cassava straw has the disadvantages of high production cost,low product competitiveness and high environmental impacts.It is necessary to develop a low-carbon,clean cellulose ethanol production technology.This study proposed the integrated technology of whole plant cassava bioethanol,and the life cycle assessment method was used to evaluate its energy efficiency,environmental impact and development potential.Firstly,different production scenarios of cassava ethanol,cassava straw ethanol and whole plant cassava ethanol were set up,and Aspen Plus and Ga Bi were employed for process simulation and life cycle assessment（LCA）.The innovation direction of bioethanol production technology for cassava and cassava straws was preliminarily determined.Compared with production technology for cassava ethanol or cassava straw ethanol,integrated technology was a cleaner method to produce ethanol with whole plant cassava.Based on the low-carbon utilization of cassava straw,it could effectively reduce the planting area,raw material input and energy consumption in the planting stage.It could also significantly improve ethanol renewability and reduce greenhouse gas emissions.The planting area required to produce 1000 L whole plant cassava ethanol was 0.29～0.31 hm².The non-renewable energy input(E_inf)of whole plant cassava ethanol was 7832～10217 MJ,the total net energy input(E_in)was 14264～15002MJ,the net energy yield（NER）was 1.41～1.49,the reproducibility（Rn）was 2.07～2.71,and the global warming potential（GWP）was 1325～1642 kg CO₂ eq.The whole plant cassava ethanol integration technology was optimized,and the bioethanol production and utilization scheme were analyzed and screened from three angles of raw material selection,production process and product configuration.It could be found that WPC-I with the technical characteristic of producing biogas from C5sugar was a more suitable scheme for producing whole plant cassava ethanol.Its emission reduction effect was remarkable,and its reproducibility was high.Meanwhile,the GWP（1553～1569 kg CO₂ eq.）and NER（1.35～1.45）were less affected by the change of fermentation efficiency.Besides,the higher straw utilization rate helped to improve the reproducibility and reduce environmental emissions.It was more appropriate to use ethanol produced by the WPC-I to prepare ethanol-gasoline E85 for vehicles.For 1000 L E85（WPC-I）,the E_inf=13202 MJ,Rn=1.722,GWP=79.01 g CO₂eq./MJ.It means that whole plant cassava ethanol was superior to cassava ethanol.Compared with gasoline,E85（WPC-I）could reduce GWP by about 22%,and it could significantly improve net energy yield and reproducibility.This study provides a new idea for the high-value utilization of waste cellulose materials such as cassava straw.It helps guide the further innovation of bioethanol production,and it can also guide the suggestions for the development of related bioethanol industry.