shaft connected double water wheel to lift water back in closed loop

Question

This is meant for mechanical closed system for hydroponics. Two wheels connected by same shaft so the wheel going down lifts the water back with the other interconnected wheel to a slight incline. I suppose the torque created by falling water should be higher and so there's should be a difference in wheel's cups volume or radius. A high reservoir also could be used to be replenished by gravity ballast lifting pulleys once a while. Any suggestions on feasibility?

Answer 1

The device you are describing is called a pressure exchanger. They are common on high pressure reverse osmosis systems and use positive displacement pump/turbine instead of wheels. The efficiency is not 100%, (no perpetual motion) so additional input is required; such as pumping additional water to keep the system going.

I would not recommend it for your application because the cost for such a system is high and the energy recovery at the low pressure would be very low.