May 7, 2015

Sorghum can be used in Sugar Mills to Generate Electricity

Brazilian sugar/ethanol mills not only produce sugar and ethanol, they also generate the electricity necessary to operate the facility. The electricity is generated by the burning of the sugarcane residue left over after the juice is extracted. The electricity not only runs the mill, the excess electricity is sold back into the electrical grid. According to the Agency for the Commercialization of Electrical Energy (CCEE), the amount of electricity generated by the sugar mills and sold back into the grid increased by 34% during the first trimester of 2015.

During the summer rainy months (December through March) sugarcane is generally not harvested in southern Brazil leaving the cogeneration plants with dwindling supplies of sugarcane residue to burn. To keep generating the electricity, mill operators turn to other sources of biomass including high-biomass sorghum hybrids.

These sorghum hybrids are planted in Aug-Sept-Oct and can vary in maturity from 110 to 160 days allowing the sorghum to be harvested from November through April depending on the planting date. The sorghum is harvested using forage equipment with the ideal moisture content of 50%. New sorghum hybrids can yield 26 to 34 tons per hectare at 50% moisture and as high as 47 tons per hectare under the right conditions. The cost of the sorghum is in the range of R$ 65 to R$ 85 per ton at 50% moisture if delivered to a sugar mill within a 20 kilometer radius.

One advantage of using sorghum is that it can also be combined with other sources of biomass to keep the electricity flowing.