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?

  • @lowleveldata
    1•10 months ago

    What’s the cost if we pipe the hot air through a steam engine?

    • @[email protected]
      7•10 months ago

      Heat pumps (like AC units, fridges, etc) become less efficient the greater temperature difference they have to pump the heat. So pumping heat from a 25°C room to a >100°C steam engine would become terribly inefficient. It would need more energy, which creates more environmental damage and climate crisis to source, and that energy heats the cities even more.

      The only sane way to cool cities is to get rid of as much concrete and asphalt as possible (especially the vast amounts of ground that is covered for cars), and keep only narrower sealed paths for small individial transport like bikes. Plaster everything with trees and grass and other greens. They cool down the city dramatically and are able to take up the water that comes down at extreme weather events.

      Escaping the urban hellscape cannot be achieved by building more stuff and throwing more energy at it. Just visit a park in your city and observe how the temperature changes, it is that simple. Mobility cannot seal all surface area, it has the be minimal, i.e. narrow paths and trains with rails that can also run on open ground / green areas. This implies of course not building secluded areas for living, shopping, working etc… It has to be a mix, where commutes are short (i.e. like european cities, not american ones).