# Thread: Thermal expansion -> pressure -> piezoelectricity -> cooling

1. Hello all, this is my first post here.
OK I was never very good with physics and have only a dictionary-level understanding of what piezoelectricity and thermal expansion are, so if this is a naive question, I beg all your pardon in advance.

So I've been thinking that it's a bummer that we use huge amounts of energy to cool ourselves off in the summer when there ought to be some way to suck the thermal energy out of the air and either use it or at least turn it into energy that is not heat. So here's my idea:

1) Tightly sandwich layers of a material with high thermal expansion in the high-room temperature range with a piezoelectric material.
2) When the ambient heat causes thermal expansion, it will be stopped by the piezoelectric material, exerting pressure, which will be turned into electricity.
3) Will the thermal expansion and mechanical stress to electricity conversion act as a heat sink, cooling as expansion happens, and then being replenished by further ambient heat? I suspect this may be where my idea falls apart..

Anyway I was just wondering if the idea might work (I was thinking cooling panels for ceilings), or if anything similar has been proposed (capture ambient heat and convert it into other energy that is either useful or at least not offensive to the senses). My other idea is some sort of reversible chemical reaction that is endothermic at room temp and then on exothermic reversal releases the energy as something other than heat... but that's for another thread.

2.

3. Originally Posted by Enkephalos
1) Tightly sandwich layers of a material with high thermal expansion in the high-room temperature range with a piezoelectric material.
2) When the ambient heat causes thermal expansion, it will be stopped by the piezoelectric material, exerting pressure, which will be turned into electricity.
3) Will the thermal expansion and mechanical stress to electricity conversion act as a heat sink, cooling as expansion happens, and then being replenished by further ambient heat? I suspect this may be where my idea falls apart..
You hit it. Realistically, the effect would be so slight, the heat from the room you are trying to cool would quickly overwhelm the temperature of the device... except... moving on to your next point:
Originally Posted by Enkephalos
(I was thinking cooling panels for ceilings)
With enough of them, you may be able to create enough of a heat transfer to pull the heat from the room-but it would be enormously cost prohibitive.

Your intent is valid. It seems like an odd waste that the standard air conditioning unit dumps so much hot air outside. This obsevation is what led to the Heat Pump that many homes are now equipped with.

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