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Japan has opened its first osmotic power plant

(www.theguardian.com)
301 points pseudolus | 1 comments | 25 Aug 25 02:53 UTC | HN request time: 0.382s | source
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elil17 ◴[26 Aug 25 17:55 UTC] No.45029999[source]▶
They really fail to explain a key point here. The reason you colocate this with a desalination plant is because you use the super-salty wastewater from desalination as the salty side of the osmosis power plant. Then you find some wastewater which is low in salt (such as semi-treated sewage), and use that as the fresh side of the osmosis power plant.

The end result is that the salty wastewater is partially diluted, which means it has a lower environmental impact when it is discharged to the ocean.

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1. kulahan ◴[31 Aug 25 05:12 UTC] No.45080536[source]▶
Wow, missing this point in the article is pretty silly - thanks for pointing that out, that’s a pretty cool aspect.

But, if it’s in any way efficient, why not just use some of the fresh water you produce? Doesn’t that kinda become free power in a sense?

Using fresh water to power a desalinization plant just seems counterintuitive to me, I guess, but maybe (certainly) I’m misunderstanding something