when freshwater meets seawater... blue the new green

[butters]

https://www.thelondoneconomic.com/news/environment/new-battery-is-powered-by-seawater-152757/

seawater-powered batteries, only taken more than half a century, first introduced by British engineer R E Pattle in the prestigious science journal Nature – in 1954.

If scaled up the technology could provide adequate voltage and current for any coastal treatment plant, said Dr Dubrawski.

Surplus power production could even be diverted to a nearby industrial operation, such as a desalination plant.

Added Dr Dubrawski: “It is a scientifically elegant solution to a complex problem.

“It needs to be tested at scale, and it doesn’t address the challenge of tapping blue energy at the global scale – rivers running into the ocean.

“But it is a good starting point that could spur these advances.”

To assess its full potential in municipal wastewater plants, the researchers are now seeing how the system functions with multiple batteries working simultaneously.

Blue energy, or ‘salinity gradient power’ to give it the scientific term, was estimated in the 1970s to have the potential of up to 2.6TW (terawatts) a year.

This would be enough to meet almost the entire global electricity demand. When the mouth of a river meets the sea, huge volumes of fresh and salty water meet.

During the mixing they diffuse quickly to reach an equilibrium – releasing as much energy as the same volume of water falling from a 250 metre hydroelectric dam.

Experts say the phenomenon is one of the most under-exploited sources of green energy.