Sweet Sorghum as a Biofuel Crop in Nebraska.

Sweet sorghum is a potentially more energy efficient crop for ethanol production than grain crops since sugar compared with starch production by the crop requires less energy. In addition, energy use for converting starch to sugar at the ethanol plant before fermentation is avoided. Agronomic practices for rainfed sweet sorghum production were evaluated and ethanol-equivalent yields (EEY) with sweet sorghum were compared with the EEY of corn and grain sorghum at three locations in a rainfall transect across southern Nebraska. Sweet sorghum yield was not increased with N application but the grain crop yields were increased even though total N uptake was similar for the three crops. Total EEY was less with sweet sorghum compared with the grain crops but sweet sorghum net EEY was 19 to 78% more than with the grain crops. Mean estimates of energy return, as ethanol, were 3.6, 1.53 and 1.51 BTUs per BTU invested, as all fossil fuel energy, for sweet sorghum, corn, and grain sorghum, respectively. Challenges remain in the development of sweet sorghum as a bio-fuel crop, such as in harvest and processing as well as fine-tuning the agronomy and cultivar improvement. However, sweet sorghum has been found to have greater potential for energy efficient ethanol production than grain crops.