While ethanol has been hailed as a renewable fuel that is better for the environment than traditional gasoline, a recent study found that in at least one measurement it led to more pollution.
Published in Nature Geosciences, Alberto Salvo, an economist at National University of Singapore, and Franz Geiger, a physical chemist at Northwestern University, studied the environmental impacts of both fuels in Sao Paulo, Brazil, and found ethanol can lead to more ground ozone pollution.
Salvo told Nature that Sao Paulo was a good test bed as it's the largest city in the Southern Hemisphere and it had price fluctuations in ethanol between 2009 and 2011, while gasoline's price remained constant, driving more users -- up to 68 percent -- to choose the traditional fuel over ethanol.
“Our study is the only one where you have a large switch over a relatively short timescale,” Salvo said.
Using data from air monitoring systems in the city and other metrics, such as traffic and weather information, the researchers saw that the increased use of gasoline caused a 15 micrograms per cubic meter drop in ground-level ozone.
Even still, the study authors pointed out that gasoline produced worse levels of nitrogen oxides, which can cause respiratory problems. What's more, they also said that different cities could see different results when comparing the different types of fuel.
But, Salvo told Nature that the study at least shows “ethanol is not a panacea.”
Another study recently found that cellulosic biofuel was actually worse for the environment compared to gasoline, emitting 7 percent more greenhouse gas emissions.