Cheaper, cleverer desalination | Hacker News Reader

Cheaper, cleverer desalination

economist.com

62 points10ren14 comments

What little energy is needed for pumping could also be supplied in-situ from solar power. What about solar thermal driving turbines or steam engines? This has the disadvantage of requiring high-pressure pipes. Solar Stirling?

An even better idea: if possible, use tides to fill the normal-conentration seawater tank at a higher elevation, and let water flow naturally downstream. Use the same tidal basin to generate the process electricity. This would require a lot more infrastructure investment up-front, but that would pay off in the form of much lower expenses for inputs afterwards.

Or they could hire a boy to carry water with a bucket.

Or they could use a horse/mule/camel/water buffalo/elephant to push a wheel and run the pump.

Plants -> Big dumb animals -> Labor: the original solar energy.

I'd rather the community/polity got a grant so that boy could be engaged in an activity with greater economic leverage. Or better still, be in school.

Such infrastructure would be in the "hand-up, not hand-out" category to me. Also, the availability of fresh water on industrial scales would be an economic enabler in itself.

It doesn't have to be a boy. There are many poor communities around the world where fully grown men would be thankful for any job.

I'll wait for the evidence that this actually works (and with efficiency relative to the other schemes).

I remember when they won a province wide business plan contest in Vancouver, BC, and it was noted that a key reason they won (the 100k prize) was that they had an engineering review indicating their process was feasible.

I think I might just have to try it out at home sometime.

Anyone know what would make a good salt bridge that's semi permeable to na/cl (or how to treat the polystyrene)? Would an U shaped jello mixed with acid/base work?

How long before the ion bridges were clogged with biofilms, sediment, and other detritus normally present in sea water?

Ion bridge replacement is another energy input.

Very cool idea.

I'm reminded of the setup at Chena Hot Springs Resort (east of Fairbanks, Alaska), where the temperature difference between a hot spring and a normal stream, is used to run an air conditioner that keeps the interior of an "ice museum" frozen year-round. It's a very different process, of course, but it seems to me to involve similar thinking.

It's kind of like dialysis, but for seawater. Sweet.

Great idea! Instead of trying to fight osmosis, use it. It's one of those "why didn't I think of that" inventions.

Can the left over streams be mixed and reused? Since they will have higher salinity and used as a new input?

The "cleaner" streams are heavily charged with ions - the high-sodium stream with chlorine, the high-chlorine with sodium. It would probably take more energy to charge them higher than using "neutral" seawater.

Reply on news.ycombinator.com