Expansion of sugarcane ethanol in Brazil could cut GHG emissions

By Lisa Gibson | November 07, 2017

A massive expansion of land use for sugar cane growth in Brazil, and a subsequent increase in ethanol production with the feedstock could reduce global carbon dioxide emissions in the transportation sector by up to 86 percent of 2014 levels, according to research published in the October issue of the journal Nature Climate Change. Overall net global emissions could be offset by up to 5.6 percent, according to the research. And, it can be done without impeding upon environmentally sensitive areas.

The report “Brazilian sugarcane ethanol as an expandable green alternative to crude oil use,” examines three scenarios of sugar cane production expansion possible by 2045, ranging from 37.5 million hectares to 116 million hectares (144,788 to 447,879 square miles). If expanded by 116 million hectares, the Brazilian sugar cane ethanol system could offset 86 percent of 2014 CO2 emissions from oil use, and emissions resulting from land-use change to sugar cane are paid back in two to eight years, the report states. None of the land expansion scenarios include any illegal land, and the 86 percent includes potential cellulosic ethanol production from bagasse and leaves.

“Our scenarios assume a displacement of the cattle production on intensive stocking production, which will ‘open’ land for sugar cane production,” said Amanda P. de Souza, a postdoc researcher for the Institute for Genomic Biology at the University of Illinois Urbana-Champaign. “Scenario 3 also considers the conversion of natural and semi-natural vegetation that can be legally converted to cropland and the use of privately held land.”

Scenario 1, an expansion of 41.9 million hectares, includes only pastureland and assumes displacement of cattle production would be compensated by intensification on pastureland not legally usable for sugar cane growth. Scenario 2, 37.5 million hectares, considers also privately held land and accounts for the additional land that will be needed for crops and animal feeds. It assumes land in pasture will decrease as intensification reduces its footprint. Scenario 3, 116 million hectares, is similar to scenario 2, but it includes natural and semi-natural vegetation that can be legally converted to cropland.

The research uses a unique approach to model the behavior of the sugar cane crops. The mechanical model stimulates plant growth hour by hour on the basis of underlying biophysical and biochemical mechanisms, using site-specific soil properties, according to the report. Traditional methods rely on empirical relationships between yield and the individual climate variables.

The research also takes into account the competition for sugar cane to produce power, and sugar cane ethanol’s ability to compete with oil in the free market.

Brazil represents the greatest potential for the expansion and ethanol production because it has the “best and the most developed system of bioethanol production from sugar cane in the world,” de Souza said.

“Of the renewable liquid fuels produced at scale, sugar cane ethanol in Brazil is arguably the most sustainable, and among these provides the greatest offset in fossil fuel carbon emissions,” according to the report.