The most recent issue of "The New Atlantis" contains a fascinating, and I suspect for many alarming, article about the dim prospects for our purported "hydrogen economy." Robert Zubrin - an aerospace engineer - provides impressive data and a few scientific formulae to show that hydrogen is not only wildly inconvenient as a fuel, but that its production requires the input of more energy than it would provide. In short, hydrogen is a net-energy loser.
Problematically, he concludes by recommending a government-mandated creation of a flex-fuel automobile fleet, one as capable of burning fuels containing high alcohol content (e.g. ethanol) as burning fossil fuels. He doesn't subject such alternative fuels to the same "EROEI" ("energy returned on energy invested") formula as he persuasively does in regard to hydrogen. Once you account for the amount of fossil fuels needed to produce a fuel like ethanol - in the form of fuel for farm equipment, fertilizers, pesticides processing and transportation - the energy return drops close to 1:1. This does not even account for the damage done by the production of corn crops upon the land, particularly in the form of topsoil erosion.
The conclusion that few people seem willing to face is that there will be no free lunch. We've been living on an enormous credit card account whose bill is coming due. Unless we begin seriously to face this fact, our debts will overwhelm us.