[Update: I probably should have included this disclaimer originally, if you have a solid understanding of physics this will probably be redundant] I just finished reading this post by Boing Boing guest blogger Saul Griffith, and it is an absolute must read for anyone who is interested in energy, efficiency, sustainability, going green, or the way things work in general.
I recommend that you have a little spare time when you read this, so that you can follow the links and really get into what he is talking about. It is not light reading (I would call it medium) and gets a little technical, but mostly puts the information into plain English that anyone (English speaking, that is) can understand.
Mr. Griffith is clearly a person who both understands the realities of the situation and is not at all deterred by the complexity (which he shouldn't be, he has a PhD from MIT). Even when talking about trade-offs and the difficulties of alternative energy sources (like electricity for cars) there is no hint of despair or defeat, just the kind of straightforward analysis that leads to better problem solving.