I just assumed they mean clean energy.

I just assumed that they mean carbon-poor electricity.

Probably not the intention of parent, but if you could mine the uranium that is released on the oceans by the earth's crust each year you would have an effectively renewable energy source that is nuclear.

We've also got enough thorium and uranium on the moon, mars, and asteroid belt to make nuclear effectively renewable for 5 or 10 earths living full-on Jetsons lifestyles for millenia to come.

I think a lot of our energy "debate" is caught up in opinionated words... "renewable" instead of "low carbon", "electricity" instead of "energy". These words frame our thinking and dialog in a manner quite favorable to entrenched primary energy interests :/

It’s a heckuva improvement on “clean” coal which produces the most greanhouse gases per BTU of any fuel. Nuclear still suffers from the distributed waste issue without a permanent storage facility or closed-loop reprocessing. Solar and wind are the ways to go long term. Solar especially, considering insolation gives a median daily recovery potential of about 1 kWh / m^2.

Intermittent character of wind and solar power production requires additional measures to build stable power system. Backup (fossil fuel) power plants, energy storage solutions. It is not so clear-cut.

Solar and wind draw their energy from a nuclear reaction as well, albeit from a substantially greater distance.

On a long enough time scale, solar power isn't renewable either.

That's why if you look up a reasonable definition of "renewable" is has the 'in a small amount of time compared to geological processes', or something of the sort.