This idea came to me while rechecking the basics of reverse osmosis for desalination. It was noted that seawater has around 27-30 bar of natural osmotic pressure that must be overcome to generate freshwater. This corresponds to a 300m tall water column, so I imagined using the oceans' own depth to desalinate seawater with a reduced energy demand.

The two systems presented here use this principle in different ways, with their own strengths and limitations. The noria variant came first , but was more difficult to iron out.