Published on December 14th, 2009 | by Nick Chambers
Study Finds Ethanol Use Increases Ozone and Carcinogen Pollution
In a nice reminder of the fact that we can never predict the unintended consequences of even small changes to a complex system, researchers at Stanford University have found that using high blends of ethanol fuel in vehicles will likely increase health problems related to ozone as well as increase the amount of certain cancer-causing chemicals in the air we breathe when compared to the use of gasoline.
E85 (85% ethanol, 15% gasoline) produces higher amounts of a group of chemicals known as aldehydes than gasoline when burned. In addition to likely being carcinogens, aldehydes are also a precursor to the formation of ozone. Breathing ozone has been shown to cause severe respiratory problems—which is why those ionizer air cleaners that are so pervasive these days are a complete crock; they may clean particles out of the air, but they generate ozone in the process.
In any event, while the burning of gasoline also produces ozone, the researchers found that the burning of E85 in a combustion engine produces significantly more aldehydes and ozone than gasoline—especially during the winter months when temperatures are below freezing.
Using a well-established model to run some scenarios, the team calculated that at temperatures from freezing to 105°F, E85 raised the concentration of ozone in the air by up to 7 ppb more than gasoline. At temperatures from freezing down to -52°F, they found E85 raised ozone levels by up to 39 ppb more than gasoline. The model was run using predictions about how many E85 capable vehicles will be on the road in 2020, as well as estimations that vehicle emissions would be about 60% less than today, because automotive emissions reduction technology will likely improve in the next 10 years.
The scientists were quick to point out that the model is not meant to be an absolute prediction of what might happen if gasoline is replaced with E85. “What we are saying with these results is that you see an increase,” said Diana Ginnebaugh, a doctoral candidate in civil and environmental engineering. “We are not saying that this is the exact magnitude you are going to get in a given urban area, because it is really going to vary from city to city depending on a lot of other factors such as the amount of natural vegetation, traffic levels, and local weather patterns.”
Clearly the aldehyde-ozone production aspect of ethanol use is only one small part of the all the factors that need to be weighed when considering a switch to a different system. For instance, my guess is that all the other positive aspects of ethanol use (I’m talking second generation non-corn ethanol here folks), when weighed on an overall impact scale, far outweigh the negatives of continuing to use gasoline.
Ultimately, what this study does clearly point out is that, regardless of the type of fuel you are burning, the burning of things always causes the creation of nasty chemicals. This will always be the main reason that encouraging a switch to EVs has many greater benefits than simply changing one liquid fuel for another. As I’ve said in the past, I think there is a place for biofuels—clearly our shipping industry could benefit from their use and it will take decades to switch out our current fleet of internal combustion cars. But in the end, without the switch to plug-ins, my kid will still be standing at the street corner sucking in carcinogens and ozone from that tailpipe.