[solarguy]

To really have a meaningful discussion about the merits of ethanol as motor fuel, you have to talk about where the ethanol came from. In north america, that mostly means corn.

Do a google search for +corn +ethanol +eroei

You will get a huge discussion and many viewpoints. But a few facts will filter out. EROEI stands for:

Energy
Returned
On
Energy
Invested

It's a way to calculate if you get more energy out than you invested to make it. For a long time, the eroei for corn-based ethanol was 1:1 at best, meaning it took one unit of fossil energy to produce one unit of ethanol energy. This was true probably up until the late 80's. Now, best case scenario, it's 1.3:1. That means you get 30% more energy out than you invested in fossil fuel.

The problem is, you have to count every scrap of energy value of the byproducts like cattle feed to make it look even as good as 1.2 or 1.3 to one. Other independent analysts say it's still pretty close to 1:1 if you count the soil erosion and non-sustainable corn growing practices. So, realistically, you're not not saving a lick of CO2 by using ethanol. If you're home distilling ethanol, you're almost certainly at 0.8:1 or worse, meaning you get less energy out than you put in. The one possible up-side to home brew is that you might be able to use wood or other biomass to provide the process heat, so at least you're not using up more petroleum energy than you're getting out in alcohol.

Just for comparison, the eroei for biodiesel from virgin soybean oil is 2.5:1 or 3:1 depending on who you talk to. The eroei for biodiesel from waste veggie oil (fryer oil) can run as high as 6:1

Ethanol from sugar cane has a much better eroei, for a couple of reasons. One, sugar cane is a nitrogen fixer. It sucks nitrogen right out of the air so it doesn't need any (or not much) petroleum derived fertilizer. Two, sugar cane plants are almost universally designed to use waste biomass as part of the process heat, further improving the eroei. That's why Brazil has been so successful in their ethanol program.

Ethanol has been so "successful" in this country because:

1. Corn farmers have pretty good and pretty powerful lobbiests.

2. Congress critters are not that smart, and not that motivated to do what's right for the country.

It has not had ANY significant impact on our use of foreign oil.

HTH,

troy