A great reply from a slashdot thread in response to an article discussing how bioelectricity used for battery-powered vehicles would deliver an average of 80% more miles of transportation per acre of crops:

mcrbids’ reply:

Comparing energy production density to Corn-based Ethanol is like stealing candy from a baby. Corn-fueled Ethanol has a tough time doing much better than just burning fossil fuels outright in systemic carbon footprint, and in some studies, is actually WORSE than strictly burning gasoline/oil.

Yes, the average is a net improvement of anywhere from 25% to 70% return on investment, but even then, you have to consider the value of the farmland itself! We’d probably do much better by simply growing wild grass on prime farmland, harvesting it, and burying it, when looking in terms of carbon footprint!

So saying that NNN technology is X% better than bioethanol is like saying that doing X is less painful than scraping off your penile foreskin with a cheese grater.

Truthful, but not very useful. Come back when you have something that actually works. For example, what’s the benefit of bio-electricity over Photo-voltaics? Now that the latter technology is down to (or better than) $1/watt [nytimes.com], this becomes a very, very tough technology to beat, and actually works better on craptastic, rocky soil off in the desert someplace with 3 inches of rainfall per year.

Meaning, we can get back to using farmland for growing food, and stop with this silly “let’s raid the kitchen cupboard to feed our guzzling SUVs!” craze that’s been on for the last few years.