Then solar and wind aren't technically renewable either, because the sun is going to eventually consume the earth and explode.

Geothermal is renewable.

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Mordisquitos 2 days ago | parent | next [-]

However much solar or wind energy we use, the Sun will last exactly as long. This is not a matter of scale. Even if we were to build a photovoltaic Dyson sphere around the Sun, it would have the same lifespan.

That is not the case for geothermal. It could in theory be cooled down if exploited at a massive scale.

Saying geothermal is not renewable is not an indictment nor a criticism. Geothermal is great and we should use it more. It's just technically not renewable, but that doesn't matter.

	▲	ahhhhnoooo a day ago \| parent [-]
		I guess there's a point where that's arguably true. But it's not correct universally, and it's certainly not true if you look at earth and the sun. The heat generated within the earth comes from nuclear decay and the energy radiates out from the planet. It would do that no matter what. Humans can tap into it and it would have the same lifespan. If humans somehow started extracting the heat leftover from the planets formation, then yeah, that is exhaustible. There's about 100,000,000,000 times our total annual energy (not electricity) use in there. Planet only has 5 billion years left, and only about 1 billion livable years. That time gets considerably shorter if we start pumping that energy to the surface, because we cook the surface with the waste heat. So even assuming it was technologically possible to access the heat there, you could not draw enough to exhaust it in the time frame you have remaining to do so without killing the biosphere.

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delichon 2 days ago | parent | prev [-]

And a new star will eventually form from the debris, so "renewable" is a function of time scale.

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direwolf20 2 days ago | parent [-]

And after a hundred generations of this there will be no fusible material left. We can extract energy from rotating black holes until they stop, and then the universe is dead.

	▲	delichon 2 days ago \| parent [-]
		So solar energy is renewable over a human lifetime, not renewable over a stellar lifetime, renewable over a stellar formation cycle, not renewable over the lifetime of a universe, and renewable if universes turn out to be cyclical. And all but the first are pendantry in the context of renewable energy conversations.