ABSTRACT
The 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 the fuel cells, and in the biochemical production in a biorefinery context. However, it is necessary to pretreat the biomass to enhance the yield of the bioethanol prior to the bioethanol production through the hydrolysis and fermentation of the biomass. The research in the fields of hydrothermal pretreatments of the biomass has also intensified in recent years. Steam explosion- and liquid hot water (LHW)-based hydrothermal treatments such as LHW, hot compressed water (HCW), and autohydrolysis pretreatments of the biomass have been widely researched to increase the sugar and bioethanol yield in this context. Further, the most prolific primary types of the biomass have been biomass constituents, wood, agricultural residues, and to a lesser extent biomass in general. Further, the most prolific individual biomass have been lignin, cellulose, hemicellulose, wood, corn stover, wheat straw, hardwood, and to a lesser extent softwood, sugarcane bagasse, corncobs, lignocellulosic biomass, and poplar. 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 number of review papers on the hydrothermal pretreatment of the biomass, there has been no updated review of the most-cited 25 articles in this field. Thus, this book chapter presents a review of the most-cited 25 articles in the field of the hydrothermal pretreatments of the biomass. Then, it discusses the key findings of these highly influential papers and comments on the future research priorities in this field.
