The weakness for sweet taste in human beings led to domesticated cultivation of sugarcane from which sweetener materials like crystalline sugar, jaggery and invert syrups are made. Sugar finds extensive use in almost all processed foods with sweet taste and it was only in the recent past that High Fructose Corn syrup (HFCS) became the preferred sweetener for the beverage industry due to reasons like cost, ease of use and slightly more sweetness compared to cane sugar or that from sugar beets. It is another matter that HFCS became the center of great controversy because of its alleged role in contributing to obesity in some countries where its use is widespread. Between sugar cane and sugar beets, former is the predominant sugar source world over, almost six times more, with the latter limited to some countries like the US and Europe.
Brazil is the top most country in sugar cane cultivation as its climate and land are best suited for this plant and provides an excellent example of utilizing a crop for highest returns possible. Brazil leads the world in ethanol production accounting for almost 40% of ethanol production in the world and had pioneered the concept of alternate fuel to fossil fuels through use of alcohol blended with gasoline as auto fuels. Its E25 gasohol blend runs almost all the vehicles in the country limiting the pollution caused by conventional automobile exhaust. Producing sugar cane to the extent of 540 million tons an year, 45% goes for sugar production and 55% is used for ethanol generation via the yeast fermentation. The bagasse accounts for about 35% of the energy present in sugar cane plant while 30% goes with sugar and remaining 35% remains in the leaves and the tips of the cane harvested, Using bagasse as feed stock Brazil generates electricity to the extent of 3GW currently which is likely to exceed 12.2 GW by 2014.
Bagasse is burned to generate heat which in turn produces super heated steam in high pressure boilers for driving turbines for electricity production. Out of the 360 sugar mills in Brazil 126 of them directly converts juice into ethanol and remaining produce sugar as well as alcohol from the molasses. Bagasse, the by product in these factories goes for electricity generation, sufficient to meet the energy needs of all these factories and surplus is supplied to regional grids for a price further improving the economics of sugar and alcohol production. Almost all countries in South America depend heavily on hydroelectric power, 80% contributed by this conventional source. But sugarcane bagasse, which comes during summer when water levels in many dams are at their lowest, can generate supplemental power helpful to meet the shortfall to a significant extent.
Sugar cane cultivation also leaves behind considerable agro wastes comprising leaves, tips etc which are generally burned in the field itself, wasting precious recoverable energy in them. Chinese have demonstrated how power can be generated using these waste cellulosic matters by setting up a 180 kWh/year unit using 2 lakh tons of wastes. According to them about 1 lakh tons of CO2 emission is cut, 600 tons of SO2 emission is avoided compared to an equivalent plant using coal as feedstock. CO2 emission from power stations near cane growing fields are reabsorbed by the fresh plants making it carbon neutral. Thus integrated sugarcane processing can ensure 100% utilization of the plant for producing ethanol, sugar and power. The out put to input ratio vis-à-vis energy is highly favorable, working out to 8.3 to 10.2 when integrated projects are conceived. This means that for every unit of fossil energy used, sugarcane bagasse can generate 8.3-10.2 units of energy and the energy from bagasse is much more than that required to run a typical sugar mill .
Looking at the Indian situation the 360 million tons of sugarcane grown in the country can generate more than 4 GW electricity, if all the bagasse from the mills and the agro waste from the field are harnessed. Since sugar cane is grown in 110 countries around the world, total production being 1600 million tons, the bagasse out put from the processing facilities can produce more than 17 GW of power if properly planned and organized. Considering that sugar, as a food is becoming an anathema for health reasons, there is a case for channelizing the entire sugar cane production into ethanol and power producing facilities by the producing countries that will help them to cut down on import of fossil fuels to a significant extent.
V.H.POTTY
http://vhpotty.blogspot.com/
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