Why can't we turn heat into energy by layering hundreds

No amount of finnicking will break the law of conservation of energy. Assuming you have a perfect thermal to electricity converter, you will only be able harvest the total amount of thermal energy you have.

Second, black body radiation will always escape into space and cool down your object till it's in equilibrium with incoming rays. So if you aren't getting light, you quickly lose the ability to give off black body radiation.

Also, there's the photovoltaic effect limitations. It's impossible to produce a current with a stream of photons below a threshold energy per photon, regardless of the amount of photons. As your object cools down, photons given off will dip below this limit and all energy will cease.

You also have to deal with entropy, which pretty much stops you from using energy in a useful way an infinite amount of times.

>>7943833
I wasn't thinking about this as a way of violating entropy, just as a way of making a somewhat passive cold region by liberating thermal energy.

Is that threshold energy the only limitation for actually getting a setup as described to operate?

>>7943833
im pretty sure he means he wants to throw a block into his campfire and make it create enough charge to power his house.

RIP OP, was prob assassinated by exxon

>>7943956
Not into a campfire, just anywhere that there's no significant heat gradient but a significant amount of undesired heat, in the 0'C to several hundred degrees range.

>>7943968
> no heat gradient
That's a perpetual motion machine of the second kind

Read the Clasuis (or was it the kelvin Planck) statement for the second law

>>7943998
That doesn't explain why the machine described in the OP doesn't work though.
If it violates conservation of energy, of course it doesn't work, but using that as your sole point of reasoning isn't good because it doesn't make anything clearer; and sometimes it may be only apparent that it violates conservation of energy but rather than not working energy is balanced in an unexpected way.

>>7944080
The first law is conservation of energy
The campfire scenario described directly violates one of the FORMULATIONS of the second law.
Did you need a proof from first principles?

Kelvin statement for reference:
> It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects.

>>7944094
Kelvin's statement doesn't work as neatly when you look at the quantum scale.
Uniform heat is perfectly uniform and unmoving on a large scale, so of course nothing can be done with it, but on the small scale there are large chunks of energy flying about in the form of black body radiation.
If you have a photovoltaic plate sensitive enough, there doesn't seem to be any reason you can't use it to turn black body radiation into usable energy.

>>7944100
I wouldn't know :)
The campfire scenario just sounded very familiar

Does /sci/ play risk of rain?

>>7944681
we don't play primitive videogames like inferior unemployed NEETS here and we despise whoever wastes their life doing so.

>>7944684
>we
I despise you

>>7944681
I only play it because it's a good game for if you've got a small amount of spare time.
But it's a really shitty game. Wouldn't be half as shitty if it was moddable though.

>>7944681
>>>/v/

>thread derailed with question still not answered
Good job, /sci/.

The more I think about this, the more it seems evident that the reason this isn't done isn't because it's impossible, but because it's impractical.
Except in certain situations that don't currently exist or we don't have the technology for, it is far more practical to use a solar photovoltaic cell rather than a thermal one.

The technology for turning heat energy into electrical energy currently exists in the form of thermoelectrics (see Seebeck Effect). Thermoelectrics rely on the temperature gradient to force energetic electrons from the hot side to the cold side, allowing for electrical energy to be captured in the movement of the charge. For this reason, thermoelectrics with low thermal conductivity and high electrical conductivity are ideal.

Since the blackbody thermal radiation is primarily in the infrared region, optical region solar cells are not as effective as thermo electrics for capturing electrical energy from a thermal gradient. Ideally, you could have a very thermally absorbtive surface on the hot side of your thermoelectric and a heat dissipator on the cold side.

>>7943676
its like, why dont we capture exhaust from car engines and use the heated gas to drive a turbine for more power, there is just so little energy involved it isnt worthless

or more crudely, 'why dont hungry people just eat their own poop'

>>7946103
>>7946107
Both of these rely on a temperature gradient.
What I'm describing isn't based on the flow of heat, as it is made to work in a system of uniform temperature.

>>7946112
that's not the point of my analogy - the trace amounts of black body radiation you are picking up are so low intensity that you gain barely any efficiency at all, at a high manufacturing cost, a lot of added systematic complexity and maintenance/wear costs that likely outweigh all the gains alone

>>7946119
I'm not taking an interest in the engineering aspects of it, just whether it's physically possible.