Ethanol perhaps not so clean after all

Ethanol’s big appeal is supposed to be that it’s clean-burning, compared to gasoline. It still emits greenhouse gases, but doesn’t contribute to urban smog in the same way as traditional out-of-the-ground hydrocarbons when burned in a vehicle engine.

Well, I guess that’s technically true. According to researchers at Stanford, it contributes to smog in a different way. The New Scientist reports:

Mark Jacobson at Stanford University in California, US, modelled emissions for cars expected to be on the road in 2020. An E85-fuelled fleet would cause 185 more pollution-related deaths per year than a petrol one across the US the model predicted – most of them in smoggy Los Angeles, California.

The findings run counter to the idea that ethanol is a cleaner-burning fuel. Cars running on gasoline emit a number of pollutants – including nitrogen dioxide and organic molecules like acetaldehyde – that react with sunlight to form ozone.

However, ethanol is an even bigger culprit. Along with many of the same pollutants as gasoline, a large amount of unburned ethanol gas escapes into the atmosphere. That vapour readily breaks down in sunlight to form acetaldehyde, which can send ozone levels soaring.

This is only one study (here’s the summary at the Journal of Environmental Science and Technology, where Jacobson’s study is published; the full thing requires a subscription), but here we see the clearest example yet of the problem with governments’ “picking winners” among new technologies. Governments in the U.S. and Canada are pushing automakers to produce engines that comfortably burn high-ethanol blends of fuel, and legally requiring the inclusion of smaller amounts in the stuff that comes out of every pump.

The journal notes this very problem:

[R]ushing ahead to fix one problem can create another, cautions Hadi Dowlatabadi of the University of British Columbia (Canada). In a previous ES&T study, he found that a U.K. policy designed to reduce carbon emissions created air-quality problems by encouraging particulate-spewing diesel vehicles. He praised the new paper for “trying to point out an issue ahead of time”.

Incidentally, the New Scientist account includes a frankly bizarre passage near the end:

However, the small potential increase in pollution-related deaths predicted in the study could be a risk worth taking for a renewable fuel, environmentalists may argue.

Huh? Economists concerned with our very-long-term prospects might make that argument, or geo-strategy thinkers looking to wean the West off its dependence on a non-renewable substance whose production occurs (the Alberta oilsands notwithstanding) in unstable semi-hostile regimes abroad, but renewability in itself isn’t something I can imagine many environmentalists would be willing to pay some human lives for.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s