this post was submitted on 30 Aug 2025
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Using it to run desalination is confusing.
I created a bucket of fresh water using nothing but sea water, a membrane, and a bucket of fresh water.
Fresh water doesn't mean drinkable water, it just means not salt water. The desalination plant produces drinkable water.
It sounds like they're not quite using fresh water, but waste water. I presume it's been treated, but even if it's not 100% back to potable, if this also helps solve the problem of what to do with the brine after desalination, I think it's a win all around.
This seems like a terrible use, since these plants work by mixing fresh water with seawater (or in this case the brine leftover from desalination). I guess the catch is they can use treated wastewater instead of potable water.
This method gains very little net energy compared to other renewables.
Returning to this thread long after everyone has moved on.
How do you get enough net energy out of mixing brine from desalination with fresh water to use to separate saltwater into brine and fresh water? Especially when the energy producing method is already known to have poor efficiency?
This seems like this is just terrible at converting treated wastewater into drinking water. Must have something to do with government subsidies instead.
Why do it, then?
Is this a proof of concept/MVP build, so they can iterate more efficient versions? A vanity project? A mistake?
Because osmotic power has enormous potential in the sense that millions of cubic meters of fresh water is running into oceans all over the world every minute. If we're able to get even a low-efficiency method of using the salinity gradient to generate power working then every place a river meets the sea is essentially an unlimited (albeit low-yield) power source.
This is tech that doesn't rely on elevation (like hydropower) or weather conditions (like wind/solar) it's stable and in principle possible to set up at pretty much any river outlet, which is great!
Gotta be careful about ecosystems though. River deltas are incredibly important and fragile areas.
Dams 2.0
Oh absolutely. As with all other infrastructure, there is a cost to be paid. However, when you look at an average to small river, even routing 10 % of the water via an osmosis plant before passing it to the sea is an absolutely massive volume. There's also the point that you don't want to build these things in large, meandering, flat river deltas. You want a large salinity gradient, which means relatively small, fast-running fresh water meeting the ocean more "suddenly" than what you get in a classical river delta is the optimal source here.
Turning unpotable water into potable water with little or no additional cost, while not harming the environment, isn't exactly a loss.
Finally, power at night, when everyone's asleep and we always have had excess.
Me who is up all night using up the excess power
This is a very old school and outdated mentality.
In my part of the EU this year, we had very very many days of negative sale prices and having to curtail wind parks because just solar and wind were making up more than demand during the day. Afaik we only curtailed at night one time.
Source: wrote curtailment algorithms for wind turbines
Do you mean my mentality or the one of the new technology?
It's not necessary to produce power 24/7 since demand isn't 24/7 either. Strong peaks and valleys.
Your mentality is old school. We have often more need at night than during the day for non renewable electricity right now
I see. Do you know what's using that power?
At night?
We use less power at night. We generate a LOT less power at night. Because the sun is off for the most part.
Do you go to bed at sunset?
Do you turn off your heat at sunset in the winter? Maybe you do, but most people don't.
Also, most people with an electric car and a garage to park it can just use a cheap Level 1 charger to trickle charge it whenever it's in the garage and always have plenty of range for their commute and errands. This means all of those cars are charging. .... at night while the owner sleeps.
That's when my electric car is plugged in and taking up quite a bit of power.
That's when it should be plugged in.
So, then why are you confused about what's using power at night?
The energy can be stored for use for later during the day