Ethanol Industry in the United States and in Brazil: Sustainability Considerations

In the past thirty years the ethanol industry in the United States (US with corn) and the Brazilian (sugarcane) made significant technological improvements both in the feedstock production, conversion technologies, and their systems' integration. , Improvements in energy efficiency occurred in both countries with the learning experience and increasingly in Brazil with the production of electricity for sale to the grid in long term contracts. Also improved in both countries were conversion yields and system efficiency and production practices in the field to enhanced production capacity. Greenhouse gas emissions (GHG) have decreased following these improvements with Brazilian ethanol GHG emissions being reduced to a greater degree as more electricity is generated from bagasse and high amounts of thrash from mechanical harvest of sugarcane. Corn ethanol production using a biomass residue (e.g., corn stover) as a source of heat, power and export electricity could also reduce GHG of corn systems further (see figure 1). The semi-perennial culture growing in a tropical environment has a superior performance over an annual crop grown in temperate zones. However, this disadvantage for corn is projected to decrease if lignocellulosic biomass ethanol becomes commercially viable in the US.

Figure1. Lifecycle Greenhouse Gas Emissions Associated with Different Feeds/Processes

Acknowledgments: This work was sponsored by the U.S. Department of Energy, Office of the Biomass Program and by the Brazilian Council for Scientific Research (CNPq) as part of the bilateral collaboration between the governments of the two countries on advanced biofuels