This power is making me thirsty!

When you think about the forces that drive the world and everything on it, you can realize how much untapped power there is everywhere. However, the problem tends to be a good way to harness it all. Even popular natural energy sources like solar and wind are limited by time and weather conditions.

But salt is one source of energy that researchers have been increasingly looking into. We all know “desalinization” as the energy-consuming work done to remove salt from seawater for human or agricultural use. However, the opposite is an energy-rich natural process in which fresh water is drawn into saltwater by osmosis to balance the concentration.

A typical power-generating setup that uses this phenomenon is a pressure retarded osmosis (PRO) system. This is where a tank of fresh water is separated by a tank of saltwater by a membrane that only allows water to pass through. This way the fresh water constantly passes into the salt water because the membrane stops equilibrium from ever being achieved. This movement of water creates pressure in the saltwater tank which moves a turbine and generates power, all through natural forces.

▼ It’s very similar to how a hydroelectric dam uses gravity to make power, but without the massive structures that can only be made in very specific locations.

Image: Wikipedia/ccfarmer (Prst)

This system can also very efficiently use both the highly salty brine byproduct of typical desalinization or salt mining and treated wastewater from human use to make an even stronger PRO power generator. Such plants are already in the works, with the first one ever built by Danish company SaltPower in 2023.

▼ SaltPower’s explanation of how it works

A PRO power plant is also nearing completion in Fukuoka City and is expected to output 100 kilowatts, which is similar to SaltPower’s current output and probably enough to run 100 or so homes, depending on consumption. However, this is really just the tip of the salt deposit when it comes to what this method can accomplish.

These artificial power generators require construction and securing of the needed water types to operate, but another type of osmosis happens nonstop on a massive scale all around the world, anywhere a river meets an ocean. A research team looked into the feasibility of setting up PRO generators at these estuaries and their findings were even better than expected.

They looked at 109 large rivers in Japan and found that they could generate an average of six megawatts per power plant. This is comparable to the current outputs of solar and wind power. They also estimated that the total energy generated by the osmotic pressure of rivers feeding into oceans around the world would be over one terawatt of electricity or one-fifth of the global demand.

The next steps in research would be to better understand how much of that can be realistically harnessed and at what cost. Still, there appears to be a lot of pros and considerably few cons for making salt a major source of clean and renewable energy — and it tastes great too!

Source: The Sankei Shimbun, Hachima Kiko, Fukuoka Now, What is green living?, SaltPower
Featured image: Pakotasu
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