The by-product of sorghum ethanol production is distillers’ grains. Table 9 presents the available nutritional information for wet and dry sorghum distillers’ grains, and dry grains plus solubles. Distiller’s dried grains with solubles contain all fermentation residues, including yeast, remaining after ethanol is removed by distillation (Shurson, 2009).

2. Conclusion

It is clear that biomass production for biofuel from sweet sorghum is the best choice to be implement under hot and dry climatic conditions regarding both economic and environmental considerations. Because, sweet sorghum has higher tolerance to drought (Tesso et al., 2005), water logging, and salt (Almodares et al., 2008a, 2008b), alkali, and aluminum soils; It may be harvested 3-4 month after planting and planted 1-2 times a year (in tropical areas); Its energy output/fossil energy input is higher than sugarcane, sugar beet, corn, wheat and etc… specially in temperate areas; It is more water use efficient (1/3 of water used by sugarcane at equal sugar production); Its production can be completely mechanized and Its bagasse has higher nutritional value than the bagasse from sugarcane, when used for animal feeding. Also, by implementing agricultural practices such as adequate water and fertilizers, suitable cultivars or hybrids, crop rotation, pest management and etc. can increase productivity with focus on biofuel production from its biomass (Reddy et al., 2005). In addition, sweet sorghum has high amount of sucrose (Almodares and Sepahi, 1996) and invert sugar (Almodares et al., 2008c) which are easily converted to ethanol (Prasad et al., 2007). Therefore, it seems that sweet sorghum biomass is the most suitable raw material for biofuel production in arid regions of the world. This awareness should push government of the countries with such climatic conditions to promote the development of projects for fuel ethanol production from sweet sorghum biomass.