Global Issues
BRAZIL: Science and Sugar Cane Produce Versatile Harvest
For nearly five hundred years, sugar cane was used almost exclusively for making sugar, with a handful of by-products like rum, alcohol and molasses. Now, in Brazil, it has become a source of multiple derivatives, and the focus of much scientific and technological research.
Ethanol, or fuel alcohol, has become a major product, rivalling sugar, over the last three decades. But recently, the waste materials, like bagasse (the fibrous residue after sugar cane is crushed), straw and vinasse have grown in importance.
Vinasse, the liquid residue left over from ethanol distillation, can be used to feed the growth of microscopic algae that can produce biodiesel, a process being developed over the next few years by researchers at the Agricultural Sciences Centre (CCA) of the Federal University of São Carlos in Araras, 170 kilometres from São Paulo, the largest city in Brazil.
The nutrients in the vinasse accelerate proliferation of the algae, which are rich in fatty acids that in turn can be used to produce biofuels. Fertilisers will also be produced, as 'the algae capture up to 64 percent of the potassium present in the vinasse,' the head of the CCA's Department of Agro-Industrial Technology, Octavio Valsechi, told IPS.
Using algae to produce biodiesel has the advantage that it avoids the monoculture of oilseed crops on extensive areas of land. However, it is still not clear whether the cost of biodiesel made from algae will be higher than that made from vegetable oils. Bagasse is increasingly used to generate electricity in the sugar mills themselves. But a biomass Gasification Centre being built over the next three years in Piracicaba, 160 kilometres from São Paulo, offers even more promising prospects.
Synthetic gas, or syngas, produced at this pilot plant will generate three times the electricity currently generated from bagasse, and can also be converted into liquid fuel or a precursor material for plastics, according to the Institute for Technological Research (IPT), the São Paulo state government agency that set the project in motion and forged partnerships with several public and private bodies to make it a reality.
Syngas is normally produced from coal, but the technology to gasify biomass is only now being tested on an industrial scale. The potential for electricity generation from bagasse with current technology, by burning it directly in furnaces, is equivalent to 'one Itaipú,' a reference to the 14,000 megawatt hydroelectric complex shared by Brazil and Paraguay, according to the Brazilian Sugarcane Industry Association (UNICA) which represents the largest companies.
But using this traditional method, 'we are losing half the potential energy of the cane,' because of the humidity content of the bagasse when it is burned, Valsechi pointed out.
Increasing mechanisation of harvesting, which by 2014 will extend to the whole sugar cane crop in the state of São Paulo, that accounts for 60 percent of national production, will do away with the practice of burning the cane fields. Studies are still under way to determine the best way of collecting the straw.
© Inter Press Service (2011) — All Rights Reserved. Original source: Inter Press Service