Solar-powered desalination system requires no extra batteries

That's great news! Now if they can solve the same problem with sea water, California, Arizona and Nevada can reduce their reliance on the Colorado river and grow more crops. It is only a matter of time before it's solved. Great work, MIT!

It’s a great application, but electrodialysis on seawater takes more power—-so much that distillation is competitive. The use-case chosen is remote freshwater wells which suffer from naturally-occurring arsenic. I can only think of a few others which can’t have heavy batteries.

Here’s a state-of-the-art portable prototype with pretreatment: 0.3 l/h at 20W: https://news.ycombinator.com/item?id=31243621

Even if you could do this you'd have to pump the water back uphill to NV and AZ.

This isn't really accurate, they're targeting industrial wastewater yes but they are working with and have tested brackish water up to several thousand TDS. They had a working EDR system for drinking water installed in Gaza until relatively recently and several in India as well. I'm also skeptical they can make it work with seawater, but it absolutely works with undrinkable brackish water in many other cases too.

Getting water to heat/boil is much less impressive than coming up with a solve for the left over salt/minerals. Solve that, then I'll join in the "Great work"

Just install some additional solar powered pumps along the way

Could you save on pumping energy by sending the water to underground aquifers rather than the surface?

The amount of energy needed to pump enough water for ag uphill is insane. Well beyond "just" throwing some solar panels out there. If it was that easy we'd pump Mississippi water into west Texas (which there was a plan to do in the 60s with nuke plants, but I cannot find the name right now).

i left off the /s as to me anytime someone starts a comment off with "just ____" is usually a farcical idea. like just remove the salt from water and boom, done.

> the left over salt/minerals

There is a commercial market for salt -- and for stuff like treating roads in the winter it doesn't have to be very clean.

Otherwise, disolve it into the local waste water stream and discharge it back into the ocean.

Ok, so it's two problems to solve. Get on it MIT!

No, start with modifying the Colorado River Compact and other underlying agreements to allow more upstream retention than is currently allotted.

If this was the case, then why is the briny residue left after desalination always the thing that gets pointed back to being a big negative of desalination?

Either it's not as big of deal as people suggest, you are wildly underplaying it, or somewhere in between. I've never felt that the argument against being the cost to heat the water was a strong one since salt water pretty much means a coastline which tends to have steady wind and sun. The biggest hang up has typically been putting that brine back into the ocean.

Hah! It can be a very HN comment to "just" something especially around physical engineering.