Featured Research

from universities, journals, and other organizations

Ethanol-powered vehicles generate more ozone than gas-powered ones

Date:
December 14, 2009
Source:
Stanford University
Summary:
Vehicles running on ethanol will generate higher concentrations of ozone than those using gasoline, especially in the winter, researchers have found. That could create new health concerns in areas where ozone hasn't been a significant problem before.

New research shows that ethanol would likely worsen health problems caused by ozone, compared with gasoline, especially in winter.
Credit: iStockphoto/Jim Parkin

Ethanol -- often promoted as a clean-burning, renewable fuel that could help wean the nation from oil -- would likely worsen health problems caused by ozone, compared with gasoline, especially in winter, according to a new study led by Stanford researchers.

Ozone production from both gasoline and E85, a blend of gasoline and ethanol that is 85 percent ethanol, is greater in warm sunny weather than during the cold weather and short days of winter, because heat and sunlight contribute to ozone formation. But E85 produces different byproducts of combustion than gasoline and generates substantially more aldehydes, which are precursors to ozone.

"What we found is that at the warmer temperatures, with E85, there is a slight increase in ozone compared to what gasoline would produce," said Diana Ginnebaugh, a doctoral candidate in civil and environmental engineering, who worked on the study. She will present the results of the study on Tuesday, Dec. 15, at the American Geophysical Union meeting in San Francisco. "But even a slight increase is a concern, especially in a place like Los Angeles, because you already have episodes of high ozone that you have to be concerned about, so you don't want any increase."

But it was at colder temperatures, below freezing, that it appeared the health impacts of E85 would be felt most strongly.

"We found a pretty substantial increase in ozone production from E85 at cold temperatures, relative to gasoline when emissions and atmospheric chemistry alone were considered," Ginnebaugh said. Although ozone is generally lower under cold-temperature winter conditions, "If you switched to E85, suddenly you could have a place like Denver exceeding ozone health-effects limits and then they would have a health concern that they don't have now."

The problem with cold weather emissions arises because the catalytic converters used on vehicles have to warm up before they reach full efficiency. So until they get warm, a larger proportion of pollutants escapes from the tailpipe into the air.

There are other pollutants that would increase in the atmosphere from burning E85 instead of gasoline, some of which are irritants to eyes, throats and lungs, and can also damage crops, but the aldehydes are the biggest contributors to ozone production, as well as being carcinogenic.

Ginnebaugh worked with Mark Z. Jacobson, professor of civil and environmental engineering, using vehicle emissions data from some earlier studies and applying it to the Los Angeles area to model the likely output of pollutants from vehicles.

Because E85 is only now beginning to be used in mass-produced vehicles, the researchers projected for the year 2020, when more "flex fuel" vehicles, which can run on E85, will likely be in use. They estimated that vehicle emissions would be about 60 percent less than today, because automotive technology will likely continue to become cleaner over time. They investigated two scenarios, one that had all the vehicles running on E85 and another in which the vehicles all ran on gasoline.

Running a widely used, complex model involving over 13,000 chemical reactions, they did repeated simulations at different ambient temperatures for the two scenarios, each time simulating a 48-hour period. They used the average ozone concentrations during each of those periods for comparison.

They found that at warm temperatures, from freezing up to 41 degrees Celsius (give F conversion), in bright sunlight, E85 raised the concentration of ozone in the air by up to 7 parts per billion more than produced by gasoline. At cold temperatures, from freezing down to minus 37 degrees Celsius, they found E85 raised ozone concentrations by up to 39 parts per billion more than gasoline.

"What we are saying with these results is that you see an increase," Ginnebaugh said. "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."

Ginnebaugh said the results of the study represent a preliminary analysis of the impact of E85. More data from studies of the emissions of flex fuel vehicles at various temperatures would help refine the estimates, she said.

Paul Livingstone contributed to the study while he was a postdoctoral researcher in civil and environmental engineering. He now works for the California Air Resources Board.


Story Source:

The above story is based on materials provided by Stanford University. Note: Materials may be edited for content and length.


Cite This Page:

Stanford University. "Ethanol-powered vehicles generate more ozone than gas-powered ones." ScienceDaily. ScienceDaily, 14 December 2009. <www.sciencedaily.com/releases/2009/12/091214101408.htm>.
Stanford University. (2009, December 14). Ethanol-powered vehicles generate more ozone than gas-powered ones. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2009/12/091214101408.htm
Stanford University. "Ethanol-powered vehicles generate more ozone than gas-powered ones." ScienceDaily. www.sciencedaily.com/releases/2009/12/091214101408.htm (accessed October 23, 2014).

Share This



More Earth & Climate News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) — The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Trick-or-Treating Banned Because of Polar Bears

Trick-or-Treating Banned Because of Polar Bears

Buzz60 (Oct. 21, 2014) — Mother Nature is pulling a trick on the kids of Arviat, Canada. As Mara Montalbano (@maramontalbano) tells us, the effects of global warming caused the town to ban trick-or-treating this Halloween. Video provided by Buzz60
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) — He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) — The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins