If you have an average of MWh a city needs, having MWh is a helpful metric, as well as kW to make sure you can power the city on peak consumption. No?

See also, "Power is not Energy": https://youtu.be/OOK5xkFijPc

thanks

It's making desalination more efficient and the effluent a bit easier on the ecosystem.

They do hint at it at end:

> “It is also noteworthy that the Japanese plant uses concentrated seawater, the brine left after removal of fresh water in a desalination plant, as the feed, which increases the difference in salt concentrations and thus the energy available.”

And the "fresh" water is also "treated wastewater". That could mean a bunch of things but in most cases it's water that's released into the environment by the water treatment plant. Its quality can be as good as clean water, but most municipalities wouldn't feed that right back to the consumer, they dump in a river or lake instead.

The article also doesn't say if it produces more power than the attached desalination plant requires. I doubt it as you'd be getting close to a perpetual motion machine if so. In which case basically what you've got is a very energy efficient desalination plant, more than a power plant.

In fact, it almost seems that you could simple pull in sea water as the “low salt” water and still have a large enough delta against a brine solution.

Really interesting that it also solves the brining issue.

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.

I imagine someone out there does a cost-benefit analysis to compare this system to just fully treating and reusing the wastewater and thus needing to desalinate less saltwater.

The concentrated waste probably gets disposed of rather than trying to get the remaining water. You treat it like the results of a waste treatment plant. You might dehydrate it a bit, just so you don't have to ship the water, but you probably won't try to recover any more water than you already have.

1) It's expensive. Very very expensive.

2) It's dangerous when not operated properly, and I don't trust commercial interests operating hundreds of these due to this reason.

3) It's bad for the environment, both the mining to get the uranium and all of the processes to turn it into fuel.

4) There is no answer for spent fuel.

Whereas with solar or wind you can basically remove #1, #2, and #4, however you still have to mine and process the materials.

Anyways, nuclear will be great for some niche uses, I am sure, but it isn't the answer to our green energy prayers.

As an imperfect car analogy, the way a turbocharger uses energy from the exhaust to inject energy into the intake, in the form of compressed air.

Neither is a perpetual motion engine, but both make the useful work more energy efficient.

The region is humid and rainy for over half the year and it's only particularly dry for about a quarter of the year. And they have a comprehensive system for evacuating stormwater during the rainy season as well.

So I'd reason a guess that they have a waste water excess 1/2 to 3/4 of the year but still need the baseload capacity of the desalination plant for the remaining chunk of the year. And while you could probably switch over to plain seawater for the portion where you are running negative, it may not be worth the added maintenance/cleanup cost of having to deal with salt or brackish water for only a small portion of the year. So instead you just eat the losses for that window in exchange for the increased efficiency/lower complexity/lower operating costs.