ABSTRACT
Crude oil-based gasoline fuels have been widely used in the transportation sector since the 1920s. However, there have been great public concerns over the adverse environmental and human impact of these fuels. Hence, biomass-based bioethanol fuels have increasingly been used in blending gasoline fuels, in fuel cells, and in biochemical production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of bioethanol prior to bioethanol fuel production from feedstocks through hydrolysis of the biomass and fermentation of the resulting hydrolysates, respectively. One of the most-studied feedstocks for bioethanol fuels has been residual starch feedstocks such as corn, wheat, rice, rye, and barley residues. The research in the field of second generation bioethanol fuels from residual starch feedstocks has intensified in this context in the key research fronts of the pretreatment and hydrolysis of residual starch feedstocks and to a lesser extent the fermentation of residual starch feedstock-based hydrolysates and the production and evaluation of second generation bioethanol fuels from residual starch feedstocks. The most prolific pretreatments have been chemical, acid, alkaline, hydrothermal, ammonia, liquid hot water, and to a lesser extent steam explosion, wet oxidation, and SO2 pretreatments. Further, corn stover and wheat straw and to a lesser extent rice straw, rye straw, and barley straw have been studied intensively in this context. However, it is essential to develop efficient incentive structures for the primary stakeholders to enhance the research in this field. Although there have been a limited number of review papers on bioethanol fuels from residual starch feedstocks, there has been no review of the 25 most-cited articles in this field. Thus, this chapter presents a review of these 25 most-cited articles. Then, it discusses the key findings of these highly influential papers and comments on future research priorities in this field.
