Japan has opened its first osmotic power plant

They really fail to explain a key point here. The reason you colocate this with a desalination plant is because you use the super-salty wastewater from desalination as the salty side of the osmosis power plant. Then you find some wastewater which is low in salt (such as semi-treated sewage), and use that as the fresh side of the osmosis power plant.

The end result is that the salty wastewater is partially diluted, which means it has a lower environmental impact when it is discharged to the ocean.

This sounds pretty awesome, recycling the waterwaste in a sort of feedback loop resulting in drinking water and power.

I am kind of curious on how much you can/should optimize this process until it becomes dangerous or unmaintainable. And can we do this on more places on this planet? For instance somewhere on a desert coast or something? Could be cool to build some of those between Sahara desert and the ocean, combined with solar panels or something.