The earth already does that, we just call it our ecosystem. It's why we have clean water, carrots, coal and, and the end the chain, the internet to talk about it.
We're actually getting a bit more than we'd like. If we could get the sun to turn it down a smidge for a few hundred years while we get the gas mix in our atmosphere right it would be most helpful.
No, we need more. The main barrier to achieving the dreams of science fiction is a lack of energy to accelerate human-scale amounts of material to high speeds (then slow them down later).
Not just that even more mundane stuff becomes much easier if you have more energy - clean water (desalination), trash (vaporize & collect fractions), raw materials (can trade energy for lower input concentration in ore), polution & greenhouse gases (capture back from th atmosphere and convert to something usable or inert).
All this becomes relatively easy if you have a lot of cheap power. And you would not get it just by power saving and eficiency improvements, only with research and building of new sources.
I'd add that we not only want, but need, space travel in order to maintain the species. Once our sun or planet dies we go with it, unless we're on a different one.
No, we need to use more of what we get. We don't use hardly any of what hits the earth. I believe I read that the Sun supplies 50X the amount of energy we consume (if of course we could capture it as energy).
You are off by a few orders of magnitude, the amount of sunlight hitting just new mexico (after taking into account the losses of converting it to electricity) is about 50x the energy we consume.
