Expansion of sugarcane cultivation in Brazil for ethanol production in areas not under environmental protection or reserved for food production could potentially replace up to 13.7% of world crude oil consumption and reduce global emissions of carbon dioxide (CO2) by as much as 5.6% by 2045. These estimates come from an international study with Brazilian participation, whose results were published in the journal Nature Climate Change.
The study set out to investigate how expansion of sugarcane ethanol could help limit the rise in average global temperatures to less than 2°C by reducing CO2 emissions from the combustion of fossil fuels, as agreed by the 196 countries that signed the Paris Climate Agreement in December 2015.
The study was conducted as part of a project supported by FAPESP and by the National Institute of Science and Technology for Bioethanol (INCT Bioethanol). The participating researchers are affiliated with the University of Campinas’s Agricultural Engineering School (FEAGRI-UNICAMP) and the University of São Paulo’s Bioscience Institute (IB-USP) and Luiz de Queiroz College of Agriculture (ESALQ-USP).
They collaborated with colleagues at the University of Illinois Urbana-Champaign (UIUC), Iowa State University and the National Center for Supercomputing Applications in the United States, the University of Copenhagen and Danish Energy Association in Denmark, and Lancaster University in the United Kingdom.
The researchers used software developed at UIUC to simulate the growth of plants such as sugarcane hour by hour based on soil composition, temperature, rainfall and drought, among other parameters.
They used three different environmental policy scenarios to simulate sugarcane expansion in the context of climate change projected for 2040 and 2050 by the five main global circulation models.
Under Scenario 1, sugarcane expansion was limited to existing pasturelands that could be replaced with the crop according to the Sugarcane Agroecological Zoning Plan (ZAE Cana) established in 2009 by EMBRAPA, the Brazilian Agricultural Research Corporation.
Under Scenario 2, sugarcane production was expanded not only to areas available for the crop identified by ZAE Cana but also to areas that will not be needed to grow food crops and animal feed, even assuming a rise in demand for food in the coming decades due to population growth.
Scenario 3 was the same except that it included natural and semi-natural vegetation that can be legally converted to cropland. All three scenarios excluded environmentally sensitive areas such as the Amazon and Pantanal, which cannot be used for agricultural or industrial activities.
The analysis showed that sugarcane cultivation for ethanol production could expand to between 37.5 million and 116 million hectares under the three scenarios and that sugarcane ethanol could supply the equivalent of between 3.63 million and 12.77 million barrels of oil per day in 2045 given the projected climate change, while at the same time ensuring conservation of forests and areas reserved for food production.
As a result, it would be possible to reduce oil consumption by 3.8%-13.7% and net global emissions of CO2 by 1.5%-5.6% by 2045 compared with data for 2014.
“Our findings show it’s possible to reconcile the two key goals to which Brazil committed as part of the Paris accord: conservation of natural environments, especially the Amazon, and increasing use of renewable energy,” said Marcos Buckeridge, a professor at IB-USP and one of the authors of the article.
“The study highlights Brazil’s courage in inventing sugarcane ethanol as a biofuel and implementing it as a nationwide solution,” Buckeridge told Agência FAPESP. “This potential expansion of sugarcane wouldn’t work without integration between the agricultural and industrial segments, and this in turn underscores the importance of concentrating strongly on the science and technology of sugarcane in the coming years. We must complete the job we began, which means second-generation ethanol.”
The authors of the study note that sugarcane ethanol is a near-term scalable solution to the problem of reducing CO2 emissions in the global transportation sector.
Production of fuel ethanol from sugarcane in Brazil is far more efficient than corn ethanol production, they argue. Its CO2 emissions correspond to only 14% of oil’s. Moreover, emissions resulting from land-use change to sugarcane cultivation can be offset in just two to eight years.
“Rapid scalability is fundamental: this is what’s needed to accelerate society’s responses to climate change,” Buckeridge said. “All the evidence suggests the average global temperature rise will exceed 1.5°C in 2030. That’s not far off. Brazilian ethanol can be a great help to the planet.”