Sugarcane-based ethanol has an energy balance that is 7 times greater than that of corn-based ethanol. Energy balance is the difference between the energy expended to convert the crop into ethanol and the amount of energy released from its consumption. There are several reasons why this occurs. First, unlike sugar, only 50% of the dry mass of corn kettles (the starch) can be converted into ethanol. Once this is done, that starch must me converted into sugar before it can be distilled into ethanol. There is no need for these first steps when using sugarcane-based ethanol, for obvious reasons. This significantly reduces the operation costs of sugar-based ethanol compared to corn-based ethanol. The chart below shows the total costs of producing a cubic meter of ethanol in both Brazil and the United States. At the current exchange rate of R$1.91 for every dollar, the total domestic costs to produce a cubic meter of ethanol in Brazil is $450. This is $80 less than the costs to produce a cubic meter of ethanol in the United States, which was calculated to be $530 without the co-product credit. I decided not to count the co-product credit for the U.S. because Brazil has a similar co-product credit (bagasse), which is not accounted for in this study.
In addition to Brazil’s lower operating costs, sugarcane-based ethanol is also more productive. On average, an acre of sugarcane-based ethanol produces about twice as much ethanol as its corn-based counterpart.
Aurelie Mejean & Chris Hope. “Modeling the Costs of Energy Crops: A Case Study of US Corn and Brazilian Sugarcane”. Energy Policy 38 (2010) 547-561.