Here’s a great, great Slashdot comment someone posted to Reddit about the relatively “safety” of energy systems.
Nothing that involves a high concentration of energy and a low concentration can ever be completely safe. Energy is the ability to do work, and it may end up doing work you don’t want it to do.
[…] Read up on ‘loss of blade’ accidents for windmills [read this, in fact — Deane], dam failures for hydro, and how coal releases radiation (lots of it) and other toxins (lots of them). Read up on what chemical compounds are used in solar cells, or just how hot a commercial sterling solar engine is at the mirror’s focal point.