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It's not just Pimental. I've been keeping up on this since the '70s and until recently all of the studies have shown net energy loss of at best break even. Now all of a sudden there are claims that there is a net energy gain. It's kind of like the global warming stuff. First the tree huggers were claiming global cooling now it's global warming, and no real evidence for either. The underlying thermodynamics of the ethanol production process hasn't changed and will remain unchanged for the life of the universe. So what's changed is the assumptions.

If I'm allowed to change my assumptions at will I can make a model predict anything I want from net energy loss to net energy gain, so I'm suspicious when all of a sudden there are tax dollars to be garnered at the net energy gain position and nothing to be gained at the net energy loss assumption. Call it natural cynicism at work when the academic and business community sees a way to get a share of the pelf that the government plunders from the taxpayers.

In addition I know Pimental - took a course from him long ago(or rather knew him since I haven't seen him in decades), and at the time he struck me as pretty sharp.

Those tractors would be made anyway whether there was an ethanol industry or not and those workers would have to eat anyway whether they were working on a farm raising ethanol feedstocks or at an ethanol plant or not.

Yes, but if you're looking at energy production then the balance has to take into account every input. Just like business determining profit or loss - you have to take into account all expenses. You can't just determine it by price of goods sold minus cost of goods. You have to take into account taxes leases, etc. to determing the true output.

On coal gassification and liquid synfuel I read an article that stated there was a steady supply, but now when I google it, I can't find the article. I know the process has been around since the turn of the previous century - the Nazis used it during WWII when their petroleum supplies were cut off and they lost Ploesti. I also know that the southern company (bunch of dickheads management wise, but not bad at routine engineering) has been sucking at the government trough on making cheap and more efficient liquid synfuel since the early '80s. They havd a demo plant that was cranking out quite a few barrels, but when gas prices got cheaper, then they stopped pursuing it. I understand that they've got a quarter billion dollar grant of our tax money to restart this process.

Frankly I see a lot more benefit in this than in ethanol since we have such huge coal reserves, and there isn't any way to fudge the energy output predictions by changing the assumptions to fit what you want the results to be like you can with ethanol.

The car and driver expose on ethanol/e85 that was posted here a few weeks ago was one of the most objective looks at the stuff. If you haven't read it you should.

So you are saying nothing has changed since the 1970's except for the assumptions? That's just not true. Since the 1970's the average bushel per acre yield for corn has risen quite a bit. Also, the average number of gallons of ethanol made per bushel of corn has increased. This isn't all about thermodynamics. Distillation of alcohol is most efficient at about 172 degrees, give or take a little depending on altitude and some other factors. Distilling under a vacuum lowers the temperature required considerably, but none of that has changed since the 1970's. Yields have changed though, both in terms of per acre bushel yields and per bushel ethanol yields. Corn used in the process has been modified some, and yeasts and enzymes used in the process have been improved. They've learned a lot in the past 36 years and efficiency of the whole process from planting the corn to distilling it has improved. It probably could be improved even further. I don't really see how you can totally discount the fact that efficiency in the processes used can and have been improved, especially given that it is clear from published statistics that average per acre corn yields have improved a little just about every year in the last few decade and you have no doubt read that per bushel ethanol yields have improved as well, with modern ethanol plants now averaging about 2.8 gallons per bushel of corn.

"Yes, but if you're looking at energy production then the balance has to take into account every input. Just like business determining profit or loss - you have to take into account all expenses."

Are the calories your farm workers burn a business expense of yours? Of course not. Look, Pimentel says that gasoline is a net energy loser, that it takes 10% more energy to produce it than you end up with in the final product. The authors of the other article you linked me to went along with a positive energy balance for ethanol ranging from somewhere between 5% and 26%, saying even at the high end it wasn't very good and at the low end it was a "make work program only a politician could love" (paraphrase from memory). If it takes 10% more energy than you get in the final product to make gasoline is the oil industry worse than a make work program only a politician could love? Pimentel goes too far in assessing energy costs regardless of which fuel he is talking about. He uses old and incorrect data with respect to yields, and he makes a lot of false assumptions along the way. In the Pimentel article you linked us to for instance he claims that ethanol will in many cases take three different distillations, which is nonsense. If you use an old pot still and don't control temperature it might take three runs through the still to get rid of enough water to run the product through a molecular sieve to get the alcohol content high enough to mix it with gasoline, but no ethanol plants use such crappy old technology. They use modern column stills that produce alcohol of sufficient purity the first run every time. He and his buddy Tad Patzek all sorts of bogus assumptions in this study we were talking about and his their studies on biodiesel, seemingly believing for instance that you can't grow soybeans unless you clear cut some forrests first. The biodiesel guys also complain that the amount of lye Pimentel and Patzek claim is used in the process is about tens times that actually used. The ethanol guys claim these two don't give proper credit for the energy value of the animal feed and liquid CO2 produced in the process. Their assumptions and conclusions have been refuted again and again, and those two are about the only researchers doing studies since the mid nineties who still claim ethanol has a negative energy balance.

Maybe part of the problem is Pimentel is an entomologist and not an engineer or an economist. He's so old he's probably getting a little senile too. Patzek was a longtime employee of Shell Oil Company and founder of the UC Oil Consortium and is also a member of the Society of Petroleum Engineers, so he's probably a little biased toward alternative fuels. These guys don't publish their entire studies in peer reviewed journals. They often cite themselves as sources for data. They don't clearly state where their data or their assumptions come from. What they do spell out is easy to refute, so maybe that's why they don't believe in letting everyone in on the secrets of how they reach their wild conclusions, showing where their data came from, etc.

I'm not going to worry about this. You can believe what you want to believe. For better or worse, ethanol is here to stay.