I agree. And then you even forget the opportunity costs. Even if the value of the "thing" you're considering buying is larger than its cost, you can only spend the money once. Thus, you buy the "thing" that has the highest value for the price you pay.

Clean, as in: do you know how much greenhouse gases are emitted when getting uranium/plutonium out of the ground and processed to be able to use it in a nuclear reactor?

If you would know, you wouldn't call it clean.

Cheap is also largely untrue.

See (for example): http://www.foreignpolicy.com/story/cms.php?story_id=3250 to debunk your clean and cheap arguments.

Once oil will not be profitable enough, Shell will just buy the company with 'the good solar array network' or some other nice green energy company.

It's not just a dog; it's a _dwarf_ dog.