Scholarly research and government policy have long documented the environmental benefits of sugarcane biofuels – first and foremost, significant greenhouse gas emissions reduction compared to fossil fuels.
Unfortunately, a recent report stirred controversy by ignoring key facts about the relationship between this clean fuel and air quality in São Paulo, Brazil to suggest drivers burning more gasoline than ethanol in flex fuel vehicles caused ozone pollution levels to fall 20% from 2010-2011.
Let’s look at the facts. Research by the Air Pollution Laboratory at São Paulo University’s Faculty of Medicine reported replacing gasoline and diesel in the city’s vehicle fleet with sugarcane biofuels would significantly improve air quality – saving more than 850 lives per year, preventing more than 12,000 hospital admissions, and saving Brazil more than $190 million annually. São Paulo has been doing just that, running its light vehicles on high-blends of ethanol (yes, E15+ is just fine!) and 400 buses in São Paulo are running on renewable diesel, known locally as Diesel de Cana.
So how could these researchers come up with such contradictory findings? A combination of ignoring actual air quality data, misinterpreting the sources of ozone formation, ignoring fundamental principles of photochemistry, leaving out changes in fossil fuel quality, and basing findings on a short time period.
Brazilian Experts Say Northwestern Report “Misleading”
Five Brazilian climate and environmental experts, including a coordinating lead author of the United Nations Intergovernmental Panel on Climate Change’s 5th Assessment Report, presented this rebuttal in recent correspondence, saying the report’s conclusions are “misleading.”
According to these experts, the report’s primary data set has a number of shortcomings that results in questionable claims and inconsistent with actual air pollution measurements from the São Paulo state government’s environment agency (CETESB). The actual data tells a different story for the same period in the study:
- Ozone pollution has worsened from 2009 (58.8% of year rated “good”) to 2011 (48.4% of year rated “good”)
- 57 days were above ozone maximum standard level, in 2009 compared to 96 in 2011.
Moreover, the report didn’t consider all sources of ozone precursors, mainly nitrogen oxides (NOx) and volatile organic compounds (VOCs), ignoring high emitters like motorcycles and heavy-duty vehicles that burn fossil fuels like gasoline and high-sulfur diesel, as well as an increasing number of stationary sources, such as back up power generators, which were not included in the study.
These experts countered the erroneous claims pointing out that Brazilian fuel quality is improving, namely with reductions in sulfur content due to regulatory changes. These reductions, as well as improvements in engine technology is ignored by this ill-informed report.
Finally, in their rebuttals, these experts pointed out that the report’s three-year study period is “not sufficient to draw long-term conclusions such as the preference for a given fuel,” and real gasoline share “distorted” from a modeled and confirmed 10% share to a 50% as-shown share.
As we have often said in these pages, everyone is entitled to their opinion, but not their own facts.
Ethanol: A Better Environmental Option
Add it all up, and the study’s findings about ethanol’s contribution to air quality are misleading at best. In fact, without cleaner-burning sugarcane biofuels fueling Brazilian vehicles and sugarcane field bagasse generating bioelectricity, the country’s greenhouse gas emissions from transportation and power generation would have been 22% higher in 2006 and could be 43% higher in 2020. Since March 2003, when flex fuel vehicles were first introduced in the Brazilian market, the use of ethanol has avoided over 240 million metric tons of CO2-eq in emissions, which is about what the state of Florida emits every year.
That reality is important, considering the climate change imperative. I second what these experts said in one of their comments. They warned “readers to take precautionary steps before following such recommendations for the use of fossil fuels instead of a recognizable advanced biofuel which could [be] sustainably produced and consumed in many regions throughout the world.”