Some readers here may start thinking that I have something against ethanol (for my other posts, see: here, here, here, here, and here). That is not true. While I do have questions on the net energy balance on the production and shipment of ethanol, the potential with technologies such as cellulosic ethanol can be huge. Additionally, I am becoming more and more convinced that more interesting and useful than ethanol would be butanol. It does not mix readily with water, can be transported in regular pipelines, and has higher energy density than ethanol. Dupont and BP are working on a biofuels alliance that is looking at bio- butanol. There are some very interesting studies that have also emerged recently around the conversion of synthesis gas (syn-gas, i.e. a mixture of CO, CO2 and H2) to biofuels, including biobutanol, via the use of certain enzymatic species in a fermentation reactor. I will write on that topic as soon as I have read a bit more on it.
But here’s a recent paper from the journal Environmental Science & Technology which caught my attention. Thank you to K- for sending it to me. Reader’s beware that its a modeling study, and much like all modeling studies, there are tons of assumptions built into it, but at least I was not expecting this kind of an impact from the use of E-85 ethanol. Here’s an interesting question for scientists working in this field: Are there any public health/epidemeological studies available from Brazil where ethanol is much more widely in use and has been for some time now?
Environ. Sci. Technol., ASAP Article 10.1021/es062085v
Web Release Date: April 18,
Copyright © 2007 American Chemical Society
Effects of Ethanol (E85) versus Gasoline Vehicles on Cancer and Mortality in the United States
Mark Z. Jacobson*
Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020
Received for review August 31, 2006
Revised manuscript received February 19, 2007
Accepted March 14, 2007
Ethanol use in vehicle fuel is increasing worldwide, but the potential cancer risk and ozone-related health consequences of a large-scale conversion from gasoline to ethanol have not been examined. Here, a nested global-through-urban air pollution/weather forecast model is combined with high-resolution future emission inventories, population data, and health effects data to examine the effect of converting from gasoline to E85 on cancer, mortality, and hospitalization in the United States as a whole and Los Angeles in particular. Under the base-case emission scenario derived, which accounted for projected improvements in gasoline and E85 vehicle emission controls, it was found that E85 (85% ethanol fuel, 15% gasoline) may increase ozone-related mortality, hospitalization, and asthma by about 9% in Los Angeles and 4% in the United States as a whole relative to 100% gasoline. Ozone increases in Los Angeles and the northeast were partially offset by decreases in the southeast. E85 also increased peroxyacetyl nitrate (PAN) in the U.S. but was estimated to cause little change in cancer risk. Due to its ozone effects, future E85 may be a greater overall public health risk than gasoline. However, because of the uncertainty in future emission regulations, it can be concluded with confidence only that E85 is unlikely to improve air quality over future gasoline vehicles. Unburned ethanol emissions from E85 may result in a global-scale source of acetaldehyde larger than that of direct emissions.
Additional resources on butanol:
See links at: http://en.wikipedia.org/wiki/Butanol