it takes a lot of space and makes very little energy

That’s not true of renewable energy, so your analogy has already fallen apart. It’s an untrue stereotype concocted by people trying to hold on to their fossil fuel profits.

if the energy throughput generated by renewables is less than our consumption

It isn’t.

then we still need a different source.

And thus we don’t.

And what will we do when all the space is used to and we still need more energy?

Well for one thing, most sources of renewable energy can be built places where a huge nuclear power plant can’t, such as in the ocean, lakes, on hills or even mountains. In deserts. On a slight incline. Somewhere without a cold stream.

If anything, renewable energy is much MORE space efficient since it doesn’t need a huge flat area and the aforementioned rarer and rarer stream.

That’s literally the opposite of true. What do you think the word “renewable” means? 🤦

Let’s say a perpetual motion machine exists and you can create infinite energy from it, but it takes a lot of space and makes very little energy (let’s say 400wh) Would it solve the energy question? The answer is not really. Theoretical you have infinite energy, but in practice you’re still making a finite amount of energy at any given time. If our energy consumption exceeds what the infinite energy source creates then it doesn’t solve the energy question. You can make “infinite” amount of energy from renewables, that’s what renewable means. However if the energy throughput generated by renewables is less than our consumption then we still need a different source.

Which is not a problem when done on a larger scale by now.

And what will we do when all the space is used to and we still need more energy?

Only if we keep doing half measures like now rather than go all in. Wind, solar, thermal and wave energy combined can more than cover the world’s energy needs in perpetuity.

We will run out of space. One nuclear reactor will generate more energy than multiple parks combined.

Nope. Which parts of “already made less effective and safe by climate change that will have become fat worse by the time we build just one nuclear plant, let alone replace all fossil fuel power” did you not understand?

By that time, nuclear power will be rendered all but useless by the necessary conditions no longer existing. Renewables aren’t so fragile.

Less effective is roughly 1% less effective per 1 degree of ambient temperature rise. We will dead before it’s going to have a significant impact.

It really is not. By the time the thorium reactors that have been 10 years away for 30 years arrive, it’ll be too late. The very problem they were supposed to fix will have rendered them inoperable.

You’re thinking only in terms of the current century, I’m thinking beyond the current century. We most likely need renewables to quickly get away from fossil fuels, but eventually we will also move away from renewables because unless we build a Dyson sphere renewables are not enough to meet our future energy demands.

Edit: I don’t know what fucked up my precious edit but I’m not going to fix that on mobile.