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New Nano Desalinization Method
lbmouse writes "The Technology Review is reporting that researchers at the Lawrence Livermore National Laboratory have announced a way to use carbon nano-tube technology to reduce the cost of desalination of ocean water by 75 percent over current methods of reverse osmosis. From the article: 'The technology could potentially provide a solution to water shortages both in the United States, where populations are expected to soar in areas with few freshwater sources, and worldwide, where a lack of clean water is a major cause of disease.' The technology may also lead to new ways of eliminating carbon dioxide emitted from power plants."
Now, as sea levels rise, we can just drink it up.
Woo-Hoo!
We'd probably call it vaporware
- Do you realize what this would mean to the starving nations of the planet?
- WOW! They'd have enough salt to last forever!
Cool work nevertheless. I wish they could do something with silicon nanowires as silicon is the second most abundant element on earth.
I've heard it said that materials science is the slowest science - and it's almost certainly true. It is taking forever to get consumer products from carbon nanotubes (with a few exceptions).
But all the uses found for a new material and all the new applications discovered - in many respects it certaily seems to be the most fruitful science (at least in the engineering and day-to-day sense).
My Computer Music Tutorial Videos
I once read something about a class of fractals called >orchids.
They are the result of monitoring crowd flow dynamics and producing the formulas.
They too noticed that for a large crowd (concert, football match) crowd flow speed INCREASES with a number of small gates rather than one large gate, hence one by one through the turnstyles actually makes the process quicker.
This appears to be a similar unintuitive process.
Anyway, I know it wasn't totally on topic I just thought I would share.
liqbase
Out of curiosity, why would it be important to purify the water before separation into hydrogen/oxygen? Most of the methods I'm familiar with don't particularly care if the water is pure, the waste rate from impurities is meaningless, and cleaning just means occasional sludge removal.
"Who is the Journal of Quantum Physics going to believe?" --Stephen Hawking
Think of the other ramifications, one of the huge problems with cracking hydrogen from water is getting pure enough water to start with. If you can cut the cost of desalination significantly, you can reduce the total cost of hydrogen production.
-Rick
"Most people in the U.S. wouldn't know they live in a tyrannical state if it walked up and grabbed their junk." - MyFirs
1) Why do they bother calling it "reverse osmosis?" From a quick review of high school biology, I have come to realize "reverse osmosis" really means "pumping through a filter."
2) I saw this other method in Discover that I really liked. Basically, it proposes using deep water and methane to flash-freeze water. All you need to do is to pump methane into water of the right depth, and it instantly freezes into that flammable ice mining rigs love to dig up and play with, without like, refrigerating it. Anyways, as it freezes, all the salt gets pushed out and it floats to the top, so all you have to do is melt the ice and reuse the methane. It appealed to the recycler in me, and it seems to me some tubes and plumbing would be easier than nanotubes, eh?
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That's easy. Zoysia. That's what I've had for years and I never water. Rain is pretty irregular here in Kansas too.
Plant a lawn that works with your local climate. It's better for the environment and better for the household budget.
The obscure we see eventually. The completely obvious, it seems, takes longer. - Edward R. Murrow
Recent analysis of the test used,the methylthiazol tetrazolium (MTT) test shows that the test may have been screwed up by the fact that the MTT was binding to the nanotubes. Using a different toxicity test, NO toxicity was found.
Based on this, carbon nanotubes should probably be considered cleared of causing cell death for now.
Inconvenient for your filter, but a boon for many many other applications.
-- perl -e'print pack"H*","6e656d6f406d38792e6f7267"'
What I never understand with these kind of filters is where the waste ends up. There is quite a lot of salt in the water, so these filters should clog pretty quickly, and just rinsing them every minute does not seem to be very practical. Does anyone know how this works?
I am hard pressed that anyone living where there is normal rainfall for growing grass (i.e. Georgia) and has a water table high enough to tap with a private well isn't simply recycling the water by pumping it from below and discharging it on the surface. In fact, ground-source heat pumps are the next big thing in saving energy resources -- some of the systems are closed loop with a coil to pipe in the ground, other systems are open loop, lifting water from a well and discharging it on the surface. The various state DNR's that issue permits for such open loop systems want you to discharge on the surface -- they certainly don't want you pumping water that you have handled directly back into the aquifer without being filtered through the ground.
I agree that lawn watering is a serious use of resources in the desert Southwest U.S. You can be Fremen in your view of lawns on Arrakis, but to argue the same point on Caladan is stretching matters a bit far.
LLNL is a national laboratory. This technology will probably be available more broadly than if it was developed by a private company. This sounds like really good news for the world, especially e.g. African nations where potable water is a huge issue.
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That ocean water scheme is taking much lower grade heat, thermodynamically, than the energy in Diesel fuel, but it still requires 1000 BTU's of heat per pound of water (8000 BTU's per gallon). That is a lot of heat to take out of the environment, and a lot of heat to transfer.
Another way for more efficient desalination is to recycle that 1000 BTU/lb -- use 1000 BTU to evaporate a pound of water to purify it and then condense that water vapor to get back that heat to evaporate more water. Trouble is that water condenses at the same temperature it evaporates, and you need at least a small temperature differential to get heat to flow downhill.
There are two approaches to recycling the heat. One approach is multi-effect distillation. You evaporate at a higher temperature and pressure, and then condense at that same temperature, which you use to evaporate other water at a lower temperature and pressure in a vacuum chamber. You have a cascade of evaporators at successively lower pressures and keep reusing the same heat. This method was developed by Norbert Rillieux, the Louisiana son of a French engineer and an American former slave, and is widely used in food preparation -- sugar from cane or beets, orange juice concentrate, and so on.
The second approach is vapor compression. You boil at one temperature, but you condense at a higher temperature by compressing the vapor to a higher pressure using something akin to an automotive supercharger driven by an electric motor, and that way the heat from condensing at a slightly higher temperature and pressure is recovered by the evaporator. This requires only a single "effect" on account of the vapor pump instead of the multi-effect cascade into successively lower pressure chambers, but it needs the electric motor and vapor pump, and you need to move a lot of heat at low temperature differentials across large surface area plate heat exchangers.
Reverse osmosis is a pure mechanical process that doesn't require exchange of the 1000 BTUs per pound of water, but the osmosis membrane offers resistance to pumping in excess of the natural osmotic pressure (the pressure differential required to overcome the salinity differential, the PV work representing the true thermodynamic cost of desalinating the water, which is much less than the 1000 BTU's per pound). By the way, it is always more cost effective to desalinate slightly-salty (brackish) water from marshes or irrigation runoff or other sources than going for the highly-salty sea water on account of the energy inherent in the dissolved salt as reflected in the higher osmotic pressure).
Well, if there's salt in the water and you attempt electrolysis, you'll get chlorine gas and NaOH in solution. It's actually the modern process for producing sodium lye (aptly named the chlor-alkali process). Once you run out of chloride ions to convert to chlorine, then you start to produce hydrogen gas, but now you've got some high pH liquid in your reaction vessel, and you probably have other reactions going on that you didn't intend...
Regards,
Ross
But what would their patent be for?
...no patents should ever be granted for any general process such as filtering water, or making water filters in general.
So far what they have is a workable, small scale (no pun intended), test solution to the problem of water filtration. But there is little novel, or unobvious, in what they have done.
If there is a patent in this it will be in the process used to create commercial quantities of nanotube filters.
There are of course usually several ways of skinning your animal of choice, so in fact it is probable that there will be several patents sought for nanotube manufacturing processes - this is by and large a good thing - however...
I will leave you to draw your own analogy as regards software patents.
Could this be used to filter water from urine? That might come in handy in survival situations, or in closed environments such as habitable space modules. Or simply for weirdo geeks.