Renewable and nuclear power today, consume more energy in the making of them, then they produce (over 10 to 20 years).

Subsidizing them won't help - there isn't enough energy available.

If you take the long view, more then 20 years, the picture changes, but few renewables last that long. Only nuclear does.

But since no bank wants to loan money with a payout of longer than 20 years, nuclear doesn't get built. That's why they talk about loan guarantees for nuclear power.

There is no free-rider or tragedy-of-the-commons going on here.

I don't think that's true. [1]

> But since no bank wants to loan money with a payout of longer than 20 years, nuclear doesn't get built.

That's an oversimplification. There are numerous reasons why nuclear isn't being built, not the least of which are the various NIMBY and other environmental concerns, and the fact that things like Thorium reactors have yet to regain popularity due to the push for weapons-grade-yielding nuclear technology over the last several decades.

[1]: http://www.eoearth.org/article/Energy_return_on_investment_%...