By using seawater to dry salt, humans discovered that the place where seawater and freshwater meet contains a kind of magical energy. A new idea then appeared: using differences in ocean salinity to produce electricity.
The energy generated by the difference in ocean salinity is calculated from osmosis. Osmosis is the process that allows a liquid to pass through a selective semi-permeable membrane. People did an experiment and placed a translucent membrane in the tank, adding salt water to one side and fresh water to the other. Salt ions present in seawater are "blocked" by the translucent membrane and cannot pass through, and only fresh water is released. In this way, fresh water enters the salt water through the translucent membrane. If another water tower is built, then under the action of osmotic pressure, the levelwater can rise up to 250 meters, or about 25 atmospheres, and the osmotic pressure of sea water and fresh water can be balanced. These high waters descend from a height of 250 meters, and the force is quite strong, enough to turn the turbine and produce electricity.
Land rivers discharge fresh water into the sea day and night. You can imagine how much energy from the salinity difference is contained at the mouths of rivers! The global salinity differential energy is estimated to be approximately 2.6 billion kilowatts.
Salinity difference energy is a kind of miraculous energy. People understand it relatively late, and it needs to be explored more deeply from basic theory. At present, many difficulties remain before the large-scale development of differential salinity energy.