Interesting question - how much will end up as sound, or in the ever smaller tail of things like storing a bit in flash memory?

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Workaccount2 2 days ago | parent | next [-]

Heat is the graveyard of energy. Everything that uses energy, or is energy, is actually just energy on it's way to the graveyard.

The energy of the universe is a pool of water a top a cliff. Water running off this cliff is used to do stuff (work), and the pool at the bottom is heat.

The "heat death of the universe" is referring to this water fall running dry, and all the energy being in this useless pool of "heat".

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devsda 2 days ago | parent [-]

Do thermophotovoltaic cells operate on different kind of heat?

Is it impossible to convert heat into other forms of energy without "consuming" materials like in the case of steam, geothermal or even the ones that need a cold body to utilize thermoelectric effect.

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LiamPowell 2 days ago | parent | next [-]

TPVs don't rely solely on the temperature of an object being high, they instead rely on two objects on either side having different temperatures. As heat moves[1] from one side to the other some of the energy from that movement is turned in to electricity.

[1]: Technically the movement itself is heat, the objects don't contain heat, rather they contain internal energy, but the two get mixed up more often than not.

	▲	supermatt 2 days ago \| parent [-]
		That movement is effectively “consuming” the differential.

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ajuc 2 days ago | parent | prev [-]

What thermal energy sources actually exploit is temperature difference, not heat. And in the end that difference averages out.

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phil21 2 days ago | parent | prev | next [-]

Almost none. A long time ago a friend and I did the math for sound, photons (status LEDs), etc and it was a rounding error of 1% or something silly like that.

And that’s ignoring that sound and photon emissions typically hit a wall or other physical surface and get converted back to heat.

It all ends up as heat in the end, just depends on where that heat is dumped and if you need to cool it or not. Most watts end up being even more than the theoretical heat per watt due to said cooling needs.

There is literally no way around the fact that every watt you burn for compute ends up as a watt of waste heat. The only factor you can control is how many units of compute you can achieve with that same watt.

	▲	Terr_ 2 days ago \| parent [-]
		Well, at least until somebody devises a system that transports or projects it so that the heat ends up somewhere not-Earth. It'd still be heating the universe in general, of course, even in the form of sprays of neutrinos. That reminds me of a sci-fi book, Sundiver by David Brin, where a ship is exploring the sun by firing a "refrigerator laser" to somehow pump-away excess heat and balance on the thrust.

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mrDmrTmrJ 2 days ago | parent | prev [-]

All sound will end up as heat.