Comments on: Ethanol Falsehood Examined

By: jane

jane — Wed, 11 Sep 2013 23:58:06 +0000

I went back to check again, because “complicated picture” made it sound like I might have missed a figure. Nope. The essay only indicates that with the investment of one gallon of gasoline, you get out more than one gallon of ethanol – presumably enough more to exceed the energy in a gallon of gasoline – so the EROEI is greater than 1. However, it doesn’t say whether to expect an EROEI of 3 or 1.2. Either way, it really does not supply an effective energy source for a high-energy society. Petroleum’s EROEI used to be as much as 100 in the easy fields – spend a barrel to get 100 barrels – and until recently was at least 20. It has been suggested by some that an EROEI of 5 is the minimum necessary to run a society like ours – if you have to start pouring more than 20% of your energy production just into producing energy, the amount that’s left to do other things with will plummet intolerably. You could maybe get away with that if you could increase gross energy production at will indefinitely, without causing a pollution crisis, but it doesn’t appear that either of those conditions holds true.

By: Greg Laden

Greg Laden — Wed, 11 Sep 2013 22:47:46 +0000

Jane, the paper does not provide an easily cited number, but shows a rather more complicated picture. You should put a comment on john’s post asking him about this.

By: jane

jane — Wed, 11 Sep 2013 21:56:27 +0000

The post to which you link does not actually say how many gallons of gasoline are used to produce a gallon of ethanol; it only says that the quantity is less than one gallon. It says the ratio of energy returned to energy invested is 5.5 to 1 for perennial ethanol – but corn isn’t a perennial, so he’s talking about something else there. The post does provide a link to the published study, but the study costs $44, so I’m limiting my reading to the abstract, which says explicitly: “[I]t is apparent that corn ethanol is not viable for replacing petroleum fuels.” Nevertheless, if you have the full study and would be willing to post their estimate of the EROEI, that would be of interest.