They used to make swamp coolers that you would put in your car window and it would blow cool air into the car. I always thought those were really cool. Completely unpowered, no electricity. It's such a simple design compared to AC units.
You draw the liquid into a tube from the source [1] and drag the outlet to a lower point. Then, as if by magic, the higher pool gets sucked through the outlet until it's drained, without any mechanical pump.
https://en.wikipedia.org/wiki/Siphon
[1] you can do it by sucking it in like a straw, but there are less gross ways like using a flexible bottle to provide pumping action