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?
some AC/ heat pump models pull the heat in the air and put it into water. those have existed for quite some time. look for “air to water heat pump”.
of course, there is some residual heat from the operation of the machine itself. and once the water is hot enough it will continue to release the heat into the air, but they do release way less heat into the air than regular AC units.
Could we run a water line through it from the water heater and use it as a supplemental water heater? At least we would be using that energy for something then.
Yes
https://www.energy.gov/energysaver/heat-pump-water-heaters
they already sell appliances that do that. Daikin Altherma line, for example, can combine A/C, sanitary hot water and home heating.
In summer it takes heat from the inside of your house an puts it in the water tank. In winter, it takes heat from the air in the atmosphere and puts it both inside your home and water tank.