Sweet Sorghum as Feedstock for Biofuel Production: A Review

Fossil energy resources, the primary source of transport fuel in the world is depleting dramatically to meet the ever-increasing energy demands globally. Crop plants are one of the best sources of renewable energy which can be used as feedstock for biofuel production. Sweet sorghum [Sorghum bicolor (L.) Moench], a C4 Graminaceous crop which has sugar-rich stalks and which is a water-use efficient crop has a very good potential as an alternative feed stock for ethanol production. It is the only crop that provides grain and stem that can be used for sugar, alcohol, syrup, jaggery, fodder, fuel, bedding, roofing, fencing, paper and chewing. Sweet sorghum juices usually contain approximately 16–18% fermentable sugar, which can be directly fermented into ethanol by yeast. Technical challenges of using sweet sorghum for biofuels are a short harvest period for highest sugar content and fast sugar degradation during storage. Various review works based on the problems of sweet sorghum were described in this review. Some studies are on the genetic potential of sweet sorghum for higher green cane yield and juice extractability where as some studies are purely on the shelf life of the juice how to preserve the juice with low cost against bacterial contamination. Studies also involve testing the potential of genotypes for superior yields of cane during post rainy and summer seasons also to make the cane available for maximum period in a year. Studies on fermentation and hydrolysis of lignocellulose are also addressed in this review.