Osmotic pressure increases at higher temperatures, so this device has a pipe of salt water or other mixture with one end being heated and the other end cooled. Osmotic pressure pulls in water at the hot end, which had pure water outside, with more than enough pressure left over to push it out the cold
end into another volume of pure water. The pipe loops back to allow the more concentrated mixture to flow back to the hot end.
Since I'm not planning a perpetual motion machine, I expect the process cools the hot side, requiring a heat source to maintain the temperature, and similarly needing a heat sink at the cold side.
Circulation: the cold concentrated brine/syrup needs to circulate back to the warm end. This can be done either with a low power normal pump or with gravity.
To do it with gravity, the pipe is made into a loop, the hot side membrane is just after the bottom, so the liquid becomes warm and dilute and light after that, so it rises to the top, and the cold side membrane is just after the top, so the liquid becomes cold and concentrated and dense after that and sinks top the bottom.
To reduce unnecessary heat dissipation, there's a counterflow heat exchanger. This can be left out if you don't care about efficiency. In one direction, the hot less concentrated brine/syrup moves to the cold end, and cools down. In the other direction, the cold more concentrated brine/syrup travels to the hot end, and warms up, and the unpressurised input water also travels to the hot end, and warms up, before getting sucked through the membrane into the brine/syrup.
The system can be run in reverse to use as a hydraulic powered heat pump. Push water in the cold end, cooling that end further, and let it flow out the hot end, heating that end further.
The system can be used to power a hydraulic vehicle, or to pressurised your home plumbing, or a town water supply, or a camping shower, or for circulating water in a solar hot water system.
If using gravity for circulation it should be basically silent.
When run in reverse, it may be possible to make a quieter air conditioner. You could also use it with a powered pump to heat water instead of a home hot water heater or a kettle.