Determination of Cellulosic Bioethanol Yield of Sweet Sorghum Genotypes Grown Under Cukurova Conditions

Abstract

Sweet sorghum and its bagasse of sweet sorghum plant which is left after extracting of its juice is used for various purposes such as first generation bioethanol, animal feed, fertilizer, biofuel and cellulosic bioethanol production and it has gained significance because of its broad use areas day by day. In this study, it was aimed to determine the theoretical cellulosic bioethanol potential of the remaining stalks (bagasse) of different sweet sorghum genotypes after extraction of its juice. For this reason, 21 different sweet sorghum (Sorghum bicolor var. saccharatum (L.) Mohlenbr.) genotypes obtained from different domestic and foreign sources were used as material. Field trials were carried out under second crop conditions in Cukurova (Adana) region in 2016 and 2017. The plants were harvested on dates that coincided with the milk-dough period of the grains in the cluster. After the leaves and inflorescences of the harvested plants were removed, the stalks were extracted and the juice was taken. Theoretical cellulosic bioethanol yields were calculated on the basis of dry matter (DM) in L ton(-1) and L da(-1) by performing cellulose and hemicellulose analyzes after the stalks (bagasse) was dried. As a result of the study, according to the two-year averages; it was determined that the cellulose content and hemicellulose content of sweet sorghum genotypes and theoretical cellulosic bioethanol yield ranged from 33.21% to 45.13%, from 20.63 to 25.36%, from 183.7 to 231.0 L ton(-1) dry matter (DM) and from 297.4 to 767.6 L da(-1) (DM), respectively. In the research, it is seen that the remaining bagasse after the removal of juice can be used for cellulosic bioethanol production and Grass1, Tracy, UNL-Hyb-3 and No91 genotypes are prominent genotypes having the capacity to produce cellulosic bioethanol over 600 L da(-1) per unit area. It is concluded that if bioethanol is obtained from the juice of sweet sorghum plant and also cellulosic bioethanol is produced from its bagasse remaining after extraction of its juice more bioethanol can be supplied from the unit area by using the whole plant having a high biomass potential and thus it can be provided advantages in terms of different aspects such as sustainability, environment and economy as a renewable energy source.