Bioelectricity: the new frontier

By Marcos Sawaya Jank

Ethanol is not the only energy output obtained from sugarcane. Bioelectricity is also produced by burning the bagasse that remains after sugarcane is processed. However, much more energy could be produced if all the bagasse, as well as the straw removed from sugarcane stalks, were utilized. Because they are not, approximately two thirds of the plant’s energy potential is still underused. The composition of sugarcane is one-third juice, one-third bagasse and one-third straw. Until recently, the juice was being used to produce sugar and ethanol while only part of the bagasse was burned to generate bioelectricity. With technology improvements, ethanol will soon be produced also from the bagasse and straw though hydrolysis, both of which will also be used to generate additional bioelectricity.
In many sugarcane plantations, the straw is burned before the cane is cut to facilitate the harvest. This is a source of pollution for rural workers as well as towns and cities in the vicinity of sugarcane fields. To remedy this inconvenience, many sugar mills have subscribed to the “Green Protocol” sponsored by the Government of São Paulo state and UNICA. The protocol calls for the eradication of straw burnings by 2014 in areas where mechanized harvesting methods can be introduced and by 2017 where mechanized harvest is currently not feasible. With the harvest fully mechanized, the straw will no longer be wasted. Instead, it will be used in high efficiency boilers, along with the bagasse, allowing a growing number of sugar and ethanol plants to become bioelectricity providers to the national grid.
Today, electricity supplied by sugar and ethanol plants totals 1,800 megawatts, a modest 3% of Brazil’s overall needs. With increased use of biomass from sugarcane, it is estimated that it would be feasible to expand the use of bioelectricity to 15 percent of the country’s needs by 2015, or 11,500 megawatts. Bioenergy from sugarcane is a particularly relevant option for Brazil because the harvesting period, when more biomass is available, occurs during the dry season, when water levels are lower and hydroelectric facilities can produce less electricity. This makes the two sources of electricity complementary.
Obviously, this technological revolution based on sugarcane demands significant investments, especially to retrofit older plants with new high-pressure boilers. Still, the industry is strongly committed to expanding this new and potentially very profitable market. The sugarcane industry and the federal government are currently discussing conditions under which plants will be connected to the grids and prices to be paid for surplus electricity they produce.
A date has been set, in late April, for the first auction dedicated to bioelectricity, which should confirm its status as one of the most significant frontiers still to be explored in Brazil’s sugar and ethanol industry – one that can lead to a revolution similar in magnitude to that brought about by ethanol. Bioelectricity can strongly reduce the need to build new hydroelectric projects in environmentally sensitive regions, while helping to do away with costly and potentially harmful options like expanding nuclear power or gas, fuel oil and coal-fired thermoelectric facilities.
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