I recently had a discussion about ACs and how they heat up cities.

Then I found an article about theoretical increase of efficiency of acs by using the heat pulled from a room to run a thermoelectric device and getting some of the energy back that was used in the ac.

I‘ve had this downstream thought many times already: since hot air is basically just energy stored. Could we theoretically pull (all?) the energy from the air (depending on desired temp) to cool it and casually fuel our society’s energy needs?

  • Haui@discuss.tchncs.deOP
    1·
    1 year ago

    Thats an awesome explanation! Thank your very much!

    So, from this and many other comments and some independent reading on my side, we‘re technically just walking batteries getting fed by the sun, being buried under ground after dying and becoming coal so to speak.

    So, theoretically, we would need to build some way to exhaust the excess heat into space (and could also get work done in the form of electricity) if we wanted to use the current overheating earth to our advantage while cooling it off. Thinking of a giant ac at this point. :D

    But jokes aside, this means that the average laypersons idea about „energy“ is false. We need „work“, not energy. Because the dissipated energy can not perform work anymore. Correct?

    • Hacksaw@lemmy.ca
      1·
      1 year ago

      Sounds like you’re on the right track there. As far as energy goes, you’re right, when things are dissipated, or all the same, you can’t extract anything. You need a differential, like a hot place and a cold one, a high voltage and a low one, a fast object and a slow/stopped one, a high object and a low one. The higher the differential the more you’re going to be able to extract. If it’s too small you might not be able to get any useful work out at all.