Ethanol Production from the Stem Juice of Different Sweet Sorghum Cultivars in the State of Pernambuco, Northeast of Brazil

Abstract

The decline in the use of fossil fuels in the future is due to the gradual depletion of their reserves and related environmental issues. Biofuels including ethanol are presented as a renewable alternative to fossil fuels. However, ethanol production, generally from sugarcane demands the use of agricultural land and other natural resources, with emphasis on water and other nutrients. Sorghum is tolerant to drought. The purpose of this study was to evaluate the potentiality of eight sweet sorghum cultivars in order to expand the ethanol production to areas with limited supply of water, not suitable for sugarcane which requires irrigation. The cultivars developed by breeding programs in the state of Pernambuco, Brazil, were analyzed for fermentation by industrial strain of Saccharomyces cerevisiae, at 33 °C, under static conditions for a period of 6 h. All assessed parameters showed some statistically significant differences among cultivars (p < 0.01), especially ethanol concentration (P) and the volumetric productivities (Qp) in the following order: Willey (P = 64.77 ± 4.4 g L−1 and Qp = 10.79 ± 0.74 g L−1 h−1), Wray (P = 59.10 ± 1.7 g L−1 and Qp = 9.85 ± 0.28 g L−1 h−1), BR 506 (P = 59.07 ± 1.3 g L−1 and Qp = 9.84 ± 0.21 g L−1 h−1) and SF 15 (54.40 ± 0.4 g L−1 and Qp = 9.07 ± 0.06 g L−1 h−1). The highest potentials for ethanol yield per hectare were observed for the cultivars SF 15 (3142.51 ± 428.47 L ha−1) and BR 506 (2193.95 ± 383.58 L ha−1). Therefore, the cultivars SF 15 and BR 506 seem to be very promising as an energy crop to be produced in areas with environmental conditions similar to Pernambuco.