Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

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

15.12.2009
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.

uis Bergeron | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Ecology, The Environment and Conservation:

nachricht 5000 tons of plastic released into the environment every year
12.07.2019 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

nachricht Climate impact of clouds made from airplane contrails may triple by 2050
27.06.2019 | European Geosciences Union

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Heat flow through single molecules detected

19.07.2019 | Physics and Astronomy

Heat transport through single molecules

19.07.2019 | Physics and Astronomy

Welcome Committee for Comets

19.07.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>