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Comment by sadness2 | Hacker News Reader

> thermodynamic limits impose a cap to energy growth lest we cook ourselves .. I’m talking about radiating the spent energy into space

Huh? This seems to be a critical premise for establishing a crisis, yet it's incoherent and essentially imaginary.

Ok, some ways we use energy have poor thermal efficiency. Light bulbs are the classic example, but look at the improvement from incandescent bulbs to LED's. Most uses of energy just move heat around within the environment, and if anything that would tend towards thermal equilibrium (a sort of microcosmic 'heat death'?), not "cooking".

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No, it's basic thermodynamics : https://www.sciencealert.com/scientists-have-developed-a-sol...

This is really cool, so there's a way to radiate heat to the space much more efficiently than the sun does, which destroys the argument of the physicist.

I think you meant "much more efficiently than the Earth does" ? It weakens the argument... but I'm uncertain whether fatally or not. You still need to radiate exponentially increasing amounts of power to outer space ! This is going to mess with surface temperature sooner or later...

All uses of energy create heat. That's practically what it means to use energy: convert it into heat. If you create more heat than can be radiated away from Earth, then you're going to create a very unsustainable situation.

There aren't any devices that operate by moving heat around unless they create additional heat to do so, or they do no work. If you're just shuffling heat around, you're not increasing entropy, and you're not achieving any observable mechanical objective, which is pretty much the whole reason we consume energy.

Is that true?

My physics is admittedly not great. However I though a 100% efficient lightbulb generates just as much heat, but at the place where the photons land (walls, floor, etc) rather than at the bulb.

I think basically any time we use energy, whether by running current through a lightbulb it by respiration after eating food, it ultimately ends up as heat.

The energy we use starts out as kinetic (wind, water), or heat (solar, thermal), or chemical, etc. We then use and it get it to do work, which in most cases converts much of it back into kinetic energy, and where there is inefficiency, heat, but even that part can end up in sinks which can find themselves ultimately back in places where heat already resided.

> which in most cases converts much of it back into kinetic energy

Are you thinking of transportation here? We burn fuel to add kinetic energy to a car or airplane but, by the time the vehicle has stopped moving, all of that energy has been converted into diffuse heat in the wheels, brake pads, atmosphere, etc, never to be harnessed again for the mostpart.

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