Harnessing the energy generated when freshwater meets saltwater | Hacker News Reader

Harnessing the energy generated when freshwater meets saltwater

phys.org

90 pointsdnetesn29 comments

There was actually already a test osmosis power plant in Norway. Unfortunately it wasn't very successful and was shut down in 2013: http://www.statkraft.com/media/news/News-archive/2013/Statkr...

The output per sq meter at 12.6W seems rather low compared to solar cells at 150-200 W/ sq meter when sunny. It's probably going to be easier to stick up a solar panel than a membrane contraption several times bigger.

The benefit of osmotic power/salinity gradient power is that it's a base load. That means it will produce power at a constant rate, regardless of the time of day, which is one of the draw backs of the more common sources of renewable sources of energy (solar, wind, etc.)

Base load is not necessarily an advantage in a future energy system. Lots of solar and wind means there will be times when all the electricity can be provided by them. So what's really needed is flexible electricity to complement that.

At that point, it's free energy. Are you really complaining?

(Yes, I do know power companies must dissipate that somehow, my own even has times whence the realtime pricing drops below zero as incentive. But a solved problem nevertheless.)

It's not not free if your power plant is free, too.

The extra energy can be dumped into pumping water up a dam. It is reasonably efficient, at 70-80%.

https://en.m.wikipedia.org/wiki/Pumped-storage_hydroelectric...

Yes, but excess solar, wind and nuclear can already do that. So introducing a new, so-called "baseload" power supplier doesn't automatically make for good economics, if anything selling it as "baseload" rather than say "cheap" is a bad sign.

Another case of the lab/field gap. So many things that work well in the lab are just terrible in the field.

In energy in particular, it seems like a good idea to increase the ratio of field to lab research.

If the membranes are anything like those in watermakers on yachts, they're pricey and gunk up easily.

This is one of those "well why didn't I think of that?" moments. It seems awesome and I hope it pans out.

But really, I came here to comment on the odd phrase I found in an image caption: "...synthetic freshwater or seawater..." I don't think I've ever heard (seen?) anyone refer to anything water-based as "synthetic" simply because the impurities were added by a human instead of by a riverbed.

And then use it in a desalination plant to make freshwater again?

If the desalination is needed at another place where the power grid extends but water pipes not - might be a useful idea.

Wires can be more effective than tubes and pumps.

A significant chunk of the world's population lives near river estuaries, so there's a further possible benefit of this by having the power source near the population and reducing transmission losses in the system.

What can be the impact of implementing it to the ecosystem?

I found nothing in the article. I hope they don't want to use it on rivers.

Not sure this is new, there are trials running in The Netherlands ( afsluitdijk )

Not being familiar with the name (though I knew the concept), "afsluitdijk" sounds like what you get when a cat swipes across the middle of your keyboard.

(Meh, why did the PC-squad downvote this? Geesh, grow up. It's okay to have fun with languages!)

As a Swede:

I also read it that way the first time.

The second time I read it as "avslutningsdike" (Swedish) or "finishing dyke" (English.) But after Googling the word it turns out afsluit is more like "tätning"/"isolation/termination".

It's more like 'closing' (something). The afsluitdijk is a bridge/dike that can be closed in case of storms.

In that case my first guess was right after all. :)

Nope, it's not. It's always (sortof) closed. It's named that way because it closed of a large part of sea, and turned it into a lake. The Oosterscheldekering does open and close.

https://en.wikipedia.org/wiki/Afsluitdijk https://en.wikipedia.org/wiki/Oosterscheldekering

(Swe) Dike = ditch

(Eng) Dyke = dam/sexual slur

https://www.merriam-webster.com/dictionary/dyke

"chiefly British spelling of dike"

The article explains that its an active research area and that there are three methods for doing this, and the new approach the article describes is combining two of them. Perhaps the Dutch system is using another method?

It looks like the Dutch system was using the PRO method.

No, the Dutch research project is investigating reverse electrodialysis (RED), not pressure-retarded osmosis (PRO)

Details : company is http://REDstack.nl

RED -> Reverse ElectroDialysis

Wow, this is so cool - seeing the place I work at on HN.

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