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Like fossil fuels come from organic matter that grew because of the sun. Is there any form of energy on that cannot be traced back to the sun in some way?

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[–] [email protected] 99 points 2 months ago* (last edited 2 months ago) (4 children)

Almost.

  • Nuclear energy comes from natural materials of the earth that arrived in their current form (it is basically recycled supernova energy from long long ago)
  • Geothermal comes ultimately from the gravitational energy of the earth itself compressing and heating it

Literally every other energy source (edit: aside from tidal and some others that people pointed out) is some form of modified and stored sunlight, in some way or another.

[–] [email protected] 3 points 2 months ago

To add to this most of the suns energy leaves the planet. Very little is retained. What the sun provides is a source of low entropy.

[–] [email protected] 18 points 2 months ago (1 children)

There is also kinetic energy when objects in space crash into the earth. RIP 🦖🦕

[–] [email protected] -1 points 2 months ago (2 children)

Hypothetically those would average to O as they strike randomly though right?

[–] [email protected] 3 points 2 months ago

This guy doesn't have numbers on their keyboard.

[–] [email protected] 1 points 2 months ago* (last edited 2 months ago) (2 children)

Well it's still incoming energy, and it's a scalar quantity. One could argue that average velocity/momentum incoming from the strikes might be zero, but I don't think that's the case either

[–] [email protected] 3 points 2 months ago* (last edited 2 months ago)

Yeah, AFAIK the big meteor showers all come from the "oncoming" direction as Earth orbits the sun. That actually might average out to zero linear momentum, depending on how they're spaced, but it definitely is reducing the Earth's angular momentum around the sun.

[–] [email protected] 1 points 2 months ago

Oh yeah that's what I was thinking of, so it would still add heat to our system ok

[–] [email protected] 10 points 2 months ago (1 children)

Geothermal comes ultimately from the gravitational energy of the earth itself compressing and heating it

One thing that’s at least 97-percent certain is that radioactive decay supplies only about half the Earth’s heat. Other sources – primordial heat left over from the planet’s formation, and possibly others as well – must account for the rest.

https://newscenter.lbl.gov/2011/07/17/kamland-geoneutrinos/

A surprising amount of geothermal energy comes from radioactive decay. Gravitational binding energy is indeed very large, but much of that heat has already radiated away before a solid crust formed.

[–] [email protected] 2 points 2 months ago (1 children)

But it sounds like, based on other comments, those things are from stars too, right? Like the sun caused the formation of our planet. It also contributes to tidal forces. And radioactive materials also came from other stars if not our own star. Right?

[–] [email protected] 0 points 2 months ago (1 children)

If main sequence stars were candles, supernova would be a nuclear bomb. Elements heavier than iron are only produced in events that are so energetic, the luminosity can exceed that of the entire galaxy they are in. What was a star becomes a neutron star or black hole afrer the supernova. Main sequence stars do not produce heavy elements until they die.

So if you want to say that radionucleotides come from stars, I won't play semantics police, but that is reductive to the point of missing out on how incredibly unique supernovae are as a stellar phenomenon.

[–] [email protected] 2 points 2 months ago

That’s so rad actually. Thank you for enlightening me. Isn’t that amazing that the elements on our planet came from those events

[–] [email protected] 22 points 2 months ago* (last edited 2 months ago) (1 children)

Although geothermal could be because of the rotation of the earth compared to its core along with tidal forces.

Although I’m not sure how much of that is from the sun or just in general.

Not sunlight though. Just the sun’s gravitational affect on the earth as well. But nuclear is definitely extrasolar

[–] [email protected] 6 points 2 months ago

It could be, but it's not. A big part is nuclear decay, strangely enough. Some is from primordial heat, and some is from the motion of the core, but mostly from regions rising and falling, not rotation.