I work for an environmental watchdog in New Zealand. I flicked through the first few pages of "Sustainable Energy - without the hot air" as it sat on a colleague's desk, took it back to my own desk and read it for two hours straight, got online and bought my own copy. It's that good. For a start, this is how environmental science should be communicated; crystal clear text and honest graphs, with simplified theory and ballpark calculations that anyone can follow, backed up by empirical data as a check on results, real examples, frequent references, and explanations of limitations. But the thinking behind it is every bit as good. MacKay is entirely pragmatic about energy supply and demand, never preachy, and he is game enough to admit when his results surprise even himself. If he is cautiously optimistic in his conclusions, it is because he has laid out a number of justifiable options. Buy it. Better still, buy it and read it.