An additional point about nuclear energy that I neglected to make yesterday.
Any future is which nuclear energy plays a large role is going to be more dangerous than a future in which nuclear is slowly fazed out. This is because of a very simple reason - the line between acceptable civilian uses of nuclear power and unacceptable uses is very small, and a lot greyer than you might imagine. The founding mission of the IAEA was originally to spread civilian nuclear technologies. Later, with the non-proliferation treaty, the IAEA was also given the duty of restricting nuclear weapons technology. That these goals are contradictory is not often stated, but they really are.
The problem with our current non-proliferation regime is not countries like North Korea, Pakistan, or even Iran. The problem with our policies is countries like Japan. Japan is a signatory to the NPT, is vocally in favour of nuclear disarmament, and despite living next to three nuclear-armed states with a history of hostilities, Japan hasn't yet succumbed and devised it's own nuclear deterrent. But if they wanted to, Japan could have nuclear weapons within a year.
This is precisely because of our nuclear regime, not in spite of it.
Now, I'm not saying Japan is going to go nuts and start threatening the US with nuclear hellfire. But the point is, so long as we accept a legitimate role for nuclear power, a country can get 90-95% of the way towards a weapons program within existing treaties. Iran, despite the US's claims, has not yet violated the NPT. Indeed, when Iran was run by the Shah, the US was enthusiastically in support of it's developing nuclear power. One wonders what the US would think of Saudi Arabia developing nuclear power today. How dangerous a world would we live in if Saudi Arabia were - possibly with US assistance - to develop 90% of the infrastructure necessary for a nuclear weapons program, only to have a coup place hardcore bin Ladenites in power? Seeing as Pakistan is already tottering on the edge, this is something we need to be serious about.
Any future in which nuclear plays a role will encourage proliferation. It's that simple.