ETHANOL, which is often promoted as a clean-burning, alternative and renewable fuel capable of partially weaning Euro-motorists and their American counterparts off crude oil-based products such as diesel and petrol, may not be so green after all.
US research demonstrates that its use would likely worsen health problems caused by ozone-based pollution, especially in winter.
A Stanford University team says that ozone production from both petrol (gasoline in the US) and E85, which is a blend of gasoline and 85% 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 – chemicals that are precursors to ozone. As it is, some cities already suffer episodes of high ozone, so any increase would be most unwelcome.
It is at temperatures below freezing that it seems the health impacts of the E85 blend would be felt most strongly.
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 petrol, 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.
Fortunately, in Europe, the market favours bio-diesels over E85.