Suchergebnisse

Rural communities in the North West Province of South Africa are among the poorest in the world with an average income of less than ZAR 8.75 (EU 0.875) per day. The South African government has committed itself to upliftment of these communities through job creation and joining of the first and second economies of the country. The Thusanang community project concept was initiated to stimulate job creation and skills development in our local communities through biofuels production. Water is scares in the North West Province with less than 200 mm of rain annually. Crops that do not threaten food security and require little water for energy production is thus favored for use as ethanol feedstock in this area. Sugar beet had been used as a source for sugar production for some time, but its development as a large scale agricultural crop in South Africa has been limited by the large production of sugarcane in tropical areas. Recent trials on tropical sugar beet production in the Eastern Cape and North Western regions of South Africa has shown promise for large scale production of tropical sugar beet for ethanol production. Sweetstem sorghum has attracted the attention of the biofuels world because of the potential of producing both food and ethanol in a single crop. The picture is not that simple though, since the plants usually contain large amounts of fermentable sugar during the flowering period, when the grains for food have not yet been formed, and then the sugar content steadily declines towards the time for harvesting of the grain. A trade­off thus needs to be found between food and energy production. The influence of various process parameters such as pH, initial sugar concentration, yeast concentration and nutrient addition on the ethanol yield obtained from sweet stem sorghum juice and tropical sugar beet juice was studied and the results is reported in this paper. The initial Brix index of the tropical sugar beet used was 21.8 wt% and 40.1wt% for the tropical sugar beet juice and the sweetstem sorghum juice respectively. All juice was fermented without prior filtering or sterilization. The highest initial sugar content was observed for the USA1 sweetstem sorghum cultivar harvested at 3 months (only energy production) and for the Hunni green sweetstem sorghum cultivar harvested at 6 months (food and energy production)