Vinicius Fernandes Nunes da Silva

Scale-up Pretreatment Studies on Sugarcane Bagasse and Straw for Second-Generation Ethanol Production

Sugarcane juice-derived ethanol (1G ethanol) has been the major renewable energy source in Brazil after the inception of National Alcohol Program in 1970. The remaining part, after the processing of sugarcane and extraction of juice (sugarcane bagasse-SB and straw-SS), are the promising sugar feedstock for cellulosic ethanol (2G ethanol) due to their abundant availability round the year and high energy content. However, sugar recovery from lignocellulosic biomass is not easy and needs intensive processing. Pretreatment to overcome the recalcitrance of these feedstocks and sugar recovery constitute almost 30 % cost of 2G ethanol production. Several pretreatment methods have been studied recently aiming to either lignin removal or hemicellulose from SB/SS for the subsequent enzymatic hydrolysis for fermentable sugar production. However, steam explosion and dilute sulfuric acid have been emerged out as two successful options for the pretreatment of SB/SS. Pilot level studies at our institute (Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol—CTBE, Campinas, Brazil), for the pretreatment of SB/SS considering steam explosion and dilute acid pretreatment, have shown the promising results. Both the pretreatment strategies are scalable and reproducible at the commercial level. This chapter deals with the experiments made on SB/SS for the steam explosion and dilute acid hydrolysis and the sugar recovery after enzymatic hydrolysis. Furthermore, process configurations for saccharification of pretreated biomass and the conversion of released sugars into ethanol have also been discussed.