Obviously this is great new tech and more water purification technologies are always needed, but given the physical boundaries it's unlikely we'll be able to use desalination as the only solution to water crises. We should still be figuring out ways to be more efficient about water use.
Based on the numbers in the article, the plant runs at 38-megawatts, consumes 100,000,000 gallons of sea-water a day, and produces 1 gallon of drinkable water per 2 gallons of sea-water.
Assuming a cost of 15.2 cents/kwh  (california seems to be one of the most expensive states), this comes out to an electricity bill of $451.70/acre-foot. A non-trivial portion of the total cost, but there is plenty of room for cost savings without reducing electricity usage.
Its also worth keeping in mind that Isreal exists, relies heavily on desalination plants, and is an agricultural exporter so we know the situation is solvable 
 Although will likely involve less wasteful agricutlure.
Israel also has a lot of reclamation systems. Most of their sewage gets filtered and the fresh water reused. In most of North America, we give minimal safe treatment to sewage and then dump it back into our water sources.
That is a very expensive process, but cheaper than desalination usually. We just need to get over the ick factor.
The idea not to perfectly clean the sewage water you created, would sound irresponsible to anybody living here, as the water cycle becomes very apparent even to the craziest right wing nut when you live in the mountains.
Humans have come up with tons of interesting ways to generate and store energy. I think we'll see some truly innovation solutions combining these methods to solve our biggest problems.
A responsible desal plant does studies on how to pump and disperse it in the ocean as best possible. Sadly in the gulf the Saudis aren't doing this and have completely ruined the local ecosystem.
Doesn't mean it doesn't make economic sense. Just that it's not an easy win.
So.. can you help reconcile your optimistic and their pessimistic assumptions? Whats the difference? Gulf doesn't wash out well. Maybe the dumped water doesn't disperse?
- Locally it doesn't disperse fast enough, 2x is a lot when talking about sealife.
- They add copper (and maybe some other stuff) to prevent fouling of the pipes, which is bad for you.
Desalination, even at today's costs, is not ruinously expensive for drinking water; but it might make farming inefficient crops (i.e., almonds) nonviable in the desert.
Farming might just move geographically, or use water more efficiently. Neither of these are necessarily bad outcomes.
Their secret? Each tree has a pipe about one meter deep. Water goes into the pipe instead of being sprayed on the ground.
There are huge amounts of low-hanging fruit in California agriculture. Water is priced too low to make it worth taking advantage of.
New/increased usage gets charged the average price.
Meanwhile, new capacity is the most expensive.
So you get subsidized if you switch to a more water-intensive crop.
I think if we can find a bunch of things that can effectively use excess power but aren't time sensitive, it'll also make renewables much more attractive.
But when would that ever happen. They'd just get used up in e.g. mining $coins.
I do agree we need to be smarter how we use the land and water. E.g. California draining its natural resources to provide cheap water in LA is not sustainable. There's no excuse for that city to not have extensive desalination as its primary means of supplying water; other places in the world are managing just fine. That 25$ cost is basically about not factoring in the true cost of destroying natural resources. Also, farming practices in California are kind of wasteful and result in lots of water being wasted.
This source says we use 80-100 gallons (304-380L) per day (in the US)
That's right, $2000 per acre-foot is $0.0061 per gallon.
So even at that cost all you have to worry about is the consequences of using the energy, the cost is no problem.
Chlorination is easy: just electrolyse the water on its way in.
Not sure what impact this has on sewage treatment.
Most of the dual-use water systems I’ve read about were fresh water vs gray water.
I mean, other than the implications of your nuclear purified drinking water.
Still, it’s feasible to overcome the last two issues, but I’m pretty sure that ignorance is going to kill us.
I asked my boss about it since he was around at the time and he hadn't work on the project but did hear about it. He said the study was paid for by Saudi Arabia and that the deal killer wasn't the cost of nuclear heat but fouling of the pipes from mineral deposits in the heat ex-changer and desalination chamber. The coatings killed the thermodynamic efficiencies of the system so there would be really high maintenance costs for continually cleaning and/or replacing the pipes. Like a lot of engineering projects it was a material science problem but nobody wanted to pay for the research to solve.
Desalination plants have the advantage that, as long as you have overcapacities compared to the average needs around, they can be turned on when energy is cheap and off when it's expensive. While they are operating, they would fill reservoirs that would provide a continuous supply of water.
There might be a thermodynamic limit onto how much energy you need to desalinate water, but the limits of harvesting renewable energy are far from being reached. We might make the sahara green, in this very century.
Er, yes. All they have is an experimental membrane that won't pass salt. Lots of those exist. Can you backwash it and get the salt out? It has to handle concentrated brine in reverse. Plus whatever other crud is in the incoming water. Most of the headaches of real desalinization plants revolve around those issues. Fragile membranes are a big issue.
This is in Nature Nanotechnology, not Desalinization, which has a more practical orientation.
From 2010:  NanoH20. That actually worked. LG Chem bought the company and they sell reverse osmosis cartridges using the technology. In the end, it was about a 20% improvement.
From 2012:  Contact membrane. That worked, but doesn't seem to have reached production. Inventor developed other interesting membrane separation systems, mostly for non-seawater applications.
From 2018:  Improved membrane production process. No product on the market yet.
Actual progress tends to be in the form of improvements in the 10-20% range. 20% gets you a startup company win.
And it seems that the progress in that area is pretty slow and anemic.
The of course brine disposal is a problem.
Don't get me wrong -- I love this work -- but it's just part of the solution.
For a lot of people in poor, hot regions a simple evaporator of concrete with a glass top is surprisingly effective, both cap ex and op ex (both pretty low, though they assume a tiny cost of labor).
I read that right now the salt is just dumped somewhere being a huge burden for flora and fauna.
1. put epoxy resin on each side of the graphene membrane to prevent swelling when exposed to water (which is important because if the graphene swells, then it allows sodium chloride to pass).
2. "drill" 1 nanometer (or smaller) holes into this membrane
so, what role does the graphene really play here? i mean, as long as you can drill tiny holes into it -- could the filter be made out of other material?
Allows for a somewhat tunable pore size, with no "drilling" necessary. Graph-di-yne and graph-tri-yne are nearest the appropriate pore size for water. A series of graphyne filters with larger pore sizes would likely be needed to clear out particulates and larger ions, so that the final purification step proceeds at a reasonable flow rate.
Similar problem as graphene, in that it has not only never been outside of the lab, but also never been outside of the computer model.