photo: Elaine via flickr
You may have seen a recent report coming out of the University of Minnesota which suggests that corn-based ethanol may be more harmful to the environment than gasoline. The health and climate change impacts are such that any green claims corn ethanol makes, are just that, claims. That's just a nutshell interpretation; check out the full report (Climate change and health costs of air emissions from biofuels and gasoline) for more detail. In any case, and rather predictably, the Renewable Fuels Association has released a rebuttal of that U.Minn. report. Here's why the RFA says ethanol is getting knocked down unfairly: Land Use Change Effect of Climate Change Based on 'Uncertain Analysis'
The rebuttal opens by asserting that this, and other recent studies on ethanol that take into account land use changes in calculating carbon emissions, are "based almost entirely upon insufficient and extremely uncertain analysis of potential land use changes."
There is not a shred of empirical, peer reviewed evidence existing today that positively links increased corn ethanol production to conversion of non agricultural lands such as grassland or forest. Increased demand for corn so far has been met largely through higher productivity per unit of land; this trend is expected to continue at an accelerated rate in the future.
I'm pretty sure that the Proceedings of the National Academy of Sciences is considered a peer-reviewed publication, but moving on...
Corn Ethanol Displaces Marginal Sources of Oil
After pointing out that there are even worse source of oil, in terms of carbon emission intensity, than gasoline (tar sands, coal-to-liquids), RFA says that,
Modern corn ethanol is displacing some of the need for gasoline from marginal sources of oil with high carbon intensity (this will be especially true for future ethanol from all sources). Thus, the climate impacts of modern and future ethanol should be compared to the climate impacts of gasoline refined from today's marginal sources of oil (such as Canadian tar sands, Venezuelan heavy crude, etc.) as well as future marginal sources. In simpler terms, the paper fails to consider that, as the GHG impacts of ethanol continue to improve, the impacts of gasoline will continue to worsen.
This is a half-truth at best. Yes, in the future if more fuel was coming from tar sands, or other non-conventional fossil fuel sources, then you could argue that ethanol was displacing some of the demand for these fuels and emissions comparisons should be made against those, rather than conventional gasoline. Currently though, this is an empty argument. As a percentage of overall oil demand, unconventional sources coming from Canada or Colorado or cooked up in coal-to-liquids plant (which aren't exactly common in the US at the moment) don't factor heavily. A comparison against conventionally-produced gasoline seems perfectly appropriate to me.
Other Reasons: Uncertain Methods, Selectivity With Data
Without going over each additional point, the rebuttal goes on to say that the original report makes errors regarding the certainty of modeling the costs of carbon mitigation; the report "ignores ethanol's ability to reduce vehicular particulate matter"; and is "selective in its discussion of ethanol's impact on air quality".
So, what do readers think? Has ethanol been unfairly treated? Or is this sort of rebuttal just a reflexive move by a lobbying organization who's had its product's reputation tarnished (once again)?
More: Renewable Fuels Association
New Study Finds Corn-Based Ethanol More Harmful Than Oil-Based Gasoline
Corn Ethanol's Greenhouse Gas Emission Reduction Better Than Thought, New Study Shows
USDA Ready to Approve GMO Corn for Ethanol Production