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Brooks Wilson's Economics Blog: Another Reaction to Ethanol as an Additive

Saturday, December 19, 2009

Another Reaction to Ethanol as an Additive

I feel for those who comment on posts; they often have insufficient room to fully articulate their thoughts.  At least this has been my experience responding to comments with comments on my blog.  Another reader made valuable comments to, "Ethanol as a Gas Additive," and I wish to respond in a post.

Anonymous said... You're assuming the only difference between your fuels was the ethanol content. Gas composition can vary quite drastically. I assume the research that has been done on this makes sure that they have consistent products. Was everything else consistent? Did you add or subtract weight from the vehicle? Speeds? Weather or temperature? Or maybe there's something goofy with your car. I believe that anecdotally this could happen from time to time, but what you're saying is not a claim that even the scientists opposed to ethanol production are claiming. That leads me to believe there's a factor that you've failed to realize.

Let me begin with an apology.  In my post, I correctly limit my conclusions by stating, "if my experience is typical."  This disclaimer should have been written in my first paragraph, not buried in the middle.  In, "Responding to Comments about Ethanol," I again limit my conclusions writing, "If my experience is the average."  Although I have found evidence that others have shared my experience, the sample size if very small and conclusions should be modest.It was my skepticism that my experience was typical that drove my search for others who shared it.  I cited "Drivers avoiding ethanol additive," written by the AP and published in the  and "Waco's Reaction to Ethanol," written by J. B. Smith for the Waco Tribune-Herald.  Both articles reference drivers who have had bad results using ethanol.  We may not be representative drivers, but my guess is that we represent a significant subset.

Anon makes a very good point suggesting that other variables than ethanol content might explain the difference in mileage.  This is called the omitted variable problem.  I do believe that the drive constituted a decent experiment.  I did consider several variables which I omitted because they were controlled or tended to favor the ethanol blend to gasoline.  For example, the weight of the load of the vehicle didn't change.  The weather got warmer but wetter as I drove south, but it was in a modest band of about 20 degrees Fahrenheit; because it was warmer, I used the air conditioning, but only in Texas and only when using gasoline.  If anything, this should favor E10 to gasoline.  The biggest omitted variable was traffic, which grows heavier driving south.  I was caught in stop and go traffic for about one hour at the merger of I35E and I35W while driving with gasoline.  I did not check tire pressure assuming that if it changed, it would have lowered again adversely affecting mileage.

Smith interviewed David Derosier who appears to be the general manager of Freddie Kish’s Complete Car Care Center and he suggests that minor mechanical problems due to ethanol use that his mechanics have encountered might be caused by inadequately blended ethanol. If correct, this is a strike against ethanol. It also raises questions about the stability of the blend.  How long does ethanol stay blended to gasoline once mixed?  I don't have a clue, but I assume that others have considered the problem.

I don't have an inherent problem with ethanol as a fuel.  For example, I don't mind food being converted to fuel.  If it is not subsidized by taxpayers, and it delivers more miles per dollar than gasoline without harming my car, I'll buy it.  But the burden of proof should be on the seller to demonstrate that ethanol is a superior product.  The government should not mandate its use. 

I have avoided environmental issues intentionally, but will make one point.  Other additives oxygenate gasoline, producing the same environmental gains.  I am willing to pay a little more for that benefit but I should be free to choose the additive I consume.   

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