My prior post referenced a link that MsHedgehog (thanks mshedge!) sent me with regard to someone running the hard numbers on energy/sustainability. The guy who wrote it is David J.D. Mackay, who is also publishing a book titled "Sustainable Energy :: Without the Hot Air". Mr. Mackay is a professor in the Department of Physics at Cambridge University.
The book is actually available free, in rough draft, in the form of PDF files (color and printable black and white versions) that you can download. There is also a four page Executive Summary.
7MB Color Version :: PDF Download
Executive Summary :: 4 pages :: PDF Download
Main Website :: www.withouthotair.com
And, he's got a blog.