Scientists demonstrate that electricity may be obtainable from water with a high salt concentration

https://phys.org/news/2022-10-scientists-electricity-high-salt.html

"Using a single 20-nm-sized nanopore, the device reached a peak power efficiency of 400 kW/m2. However, the researchers found that adding too many nanopores to the membrane actually reduced the power that could be extracted. The optimal configuration of pores, 100-nm-sized nanopores arranged in a grid with a spacing of one micrometer, yielded an osmotic power density of 100 W/m2"

Related:

Producing Renewable Energy with Osmotic Power

https://www.azocleantech.com/article.aspx?ArticleID=1729

Nanofluidic device generates power with saltwater

https://www.eurekalert.org/news-releases/1002556

Nanotech Breakthrough Converts Seawater into Renewable Energy

https://www.guardianmag.us/2023/11/nanotech-breakthrough-converts-seawater.html