system
Given the following post, respond as if you're commenting on Reddit:
human
What forms of renewable energy are available to us in space, other than solar energy?

On Earth we can utilize geothermal, hydroelectric, solar cell, and wind turbine technologies to generate some of our energy needs. Would there be any practical use with similar technologies applied towards all the radiation and other forces more prevalent in open space, particularly near-Earth?

Edit:Thanks for the responses! I'm still going through them all and it seems I left the assumption that I'm asking about propulsion and used "renewable energy" as an ambiguous term. I should have just said "energy sources". I'm not so much asking about space travel, but maintaining a sustainable energy source off-planet (not on Earth), but within our solar system-say anywhere between Earth and Jupiter respectively. The application in mind for the energy source would be anything from exploratory probes to colonization structures.

This is for a paper. I'm taking a COM 102 course and am assigned to write a paper on "sustainability". Sustainability of what? That wasn't defined to us. Many of my peers are writing about environmental conservation, while I'm going a different direction in arguing that environmental conservation will only effective as long a Earth is able to sustain our population. In my argument, so long as mass euthanasia, genocide, and global disaster are ruled out, sustaining human civilization in the long game will only be possible if a part of our collected population ups and leaves the planet, and a large portion of current resources being applied to environmental conservation should be directed towards colonization. To support my thesis, I'm looking for ongoing research on energy and food production that could be applied to making extraterrestrial colonization a practical real life solution. I came here to see if I can be pointed in the right direction on ongoing research.
gpt
Most forms of energy available to us on Earth are indirectly solar, which comes from nuclear fusion. Wind power comes from a small fraction of solar heat that results in air currents. Fossil fuels give us access to chemical energy from plants that have been building up for millions of years.

Geothermal and fission both come from unstable heavy isotopes that originate from the previous generation of stars that formed the matter from our solar system. These isotopes exist throughout the Earth, and cause heating that we extract as geothermal. If collected together, certain isotopes can produce a sustained fission reaction, which is vastly more power and energy dense then passive decay.

If by renewable you mean that you would like to collect energy "on the way" as you travel the universe, nuclear fusion is a good bet. Deuterium can be found throughout the universe, mixed in with normal hydrogen. If you can hang out by a gas giant, or catch some icy comets, you can get Hydrogen.