Has anyone seen the Colbert Report with the Dean Kamen interview? He talks about some kind of “vapor compression” water distillation that will revolutionize the availability of water, especially in the third world. Any clue as to the technology behind this invention?
Here is a link to the interview, but you have to wade through about 20 min of other stuff to get to it.
http://www.comedycentral.com/colbertreport/videos.jhtml?episodeId=164042
The patent application for the thing is given here:
The skinny - it’s a high-tech still. Fuel is burnt to run a stirling engine, which generates electricity, which runs a vapour-compression still. (More on this in a moment.) Waste heat from the stirling engine is used to pre-heat the water, which makes the vapour-compression still work with less energy input.
Distilling water by heat is a simple process - boil your dirty water to make nice clean steam, and condense the steam to make nice clean water. But you don’t have to heat water to make it boil. You can reduce the pressure on it instead.
E.g. have a cylinder and piston. Have only a small space at one side of the piston and fill it with dirty water. Withdraw the piston to create 10 times the volume. You don’t end up with a puddle of water with a vacuum above it! Instead the water boils and fills the extra space with water vapour. Then you shift the water-vapour to a second “clean” cylinder and re-compress it with a second piston to make clean water.
The advantage of mechanical distillation is that it’s cyclic, so you can have a high distillation rate from a small unit, and also it’s easy to reclaim the work that’s put in. Pulling the piston out of the dirty cylinder takes work, but the re-compressing in the clean cylinder does work. By linking the two cylinders, e.g. with a crank, you can have very efficient distillation.
That’s not to say heat distillation can’t reclaim energy. With heat distillation, you can use the cold dirty water coming in to condense the hot clean steam coming out. With a decent heat-exchanger you can do quite well. The mechanical system may be more efficient overall, especially on a small scale, but it’s not particularly revolutionary in concept.
If I had to guess, this is marketing spin. The technology might work, but Dean Kamen comes off as a legend in his own mind. Segway was supposed to revolutionize urban transport. I guess the real question is “is it significantly cheaper than traditional forms of desalinization”?
Does this technology condense water from the air or does it filter liquid water? Desalinating the water is only half the problem for interior, landlocked areas. You also have to pump the water (a lot of water) uphill. Apparently, this is a very non-trivial problem. I find it hard to believe that a technology that condensed water could produce enough to revolutionize anything.
Stranger on a Train is much more eloquent on this subject. Hepefully, he (or she) will chime in.
FWIW,
Rob
Generating electricity from the Stirling engine seems a superfluous and wasteful step - why not just use the mechanical output from the Stirling engine to drive the compressor directly?
By the way, here’s the YouTube video so you don’t have to wade through all the Colbert stuff:
http://www.youtube.com/watch?v=D5FKtvxU7c0
I wondered that myself. The patent site has links to drawings and diagrams but they aren’t working for me, so no clues there. Maybe an electrical system is more adaptable, e.g. the valve timing can alter for different operating conditions. Just a guess!
It purifies liquids, but supposedly without any filters.
How is it better than, say, reverse osmosis? Is it supposed to use much less energy? It doesn’t get around the problem of having water in the first place.
Thanks,
Rob
Yes, I saw the program and the interview and the preliminary to the demo in which Steve dumped a bag of his favorite sponsorial chips into the dirty water bucket so it could be proven that the system would un-Tostito it. All while he had pointedly turned on the faucet in the bathroom sink and let it flow for the entire program to "prove? that we did not have a water shortage.
But, I did not see the show the next day. Did they do a followup to “prove” that the Tostitoed water got thru the system as clean water?
If it works on a large scale and is competitive with osmosis it might mean that Australia will not need to spend another US$290 million on another reverse osmosis desalination plant like the one under construction in Perth.
By the way it’s desalination, not desalinization. The latter implies that you first salinated unsalinated water and then removed the salt.
I don’t know how they compare energetically. Reverse osmosis uses a membrane that needs periodic replacement, and it’s probably less compact for the same water output.
All I really know is what I understood from the patent, and they’re always irritating, generalised catch-all documents that try to claim all sorts of tangential applications and aspects. I didn’t see any claims of superior energy efficiency or comparisons to reverse osmosis, but then I was only skimming to find the technical bits.
I guess that is OK for Australia where most people live on the coasts, but it wouldn’t do much for, say, areas serviced by the Oglalla Aquifer.
I stand corrected.
Thanks,
Rob
From what I understand it generates several hundred more watts than it uses for the water, and so is a combination power generator and still.
I don’t think his claim (on the youtube clip) that ‘nothing from there gets through to here’ can be true. Anything moderately miscible with water and sufficiently volatile is going to be evaporated and condensed along with the water.
True, but for where this is designed to be used the water isn’t likely to have volatiles in it.
What a great explanation; thanks.
It will work well in situations where the problem is parasites or pathogens or salts in the water - which, yes, is most of the problem drinking water scenarios. Although industrial pollution is not an insignificant concern, and this machine won’t be able to help in all of those cases.
I mean, I think it’s a great idea, and I just hope it lives up to the hype - because there’s quite a bit of it, The Segway didn’t.
I think the whole thing is a scam. I looked for “prettygirlsmovingheavythings.com” and it wasn’t there.
The water purifier might work however.
He’s got a rather extensive list of patents–all my diabetic friends know his work on insulin pumps, for example.
Of course, there is a quick easy way to purify water contaminated by your standard paracites and bacteria- boil it. The problem is convincing people that it is a neccesary step (I often can’t be bothered myself, and have paid for it dearly pretty often) and making sure they have the firewood and time to do this.
Kamen suffers from being around too much hype, not all of it from his own creation. He made Cubic Metric Buttloads of money in medical invention, created a balancing wheelchair that let the operator ‘stand up’ (which has tremendous value in a society where everything’s 4 foot off the floor or higher), and translated that balancing tech to a consumer product that couldn’t possibly live up to the hype that was generated for it. Not necessarily of his making.
You should see his work in prosthetic limbs.
The point of THIS particular invention isn’t what it does…it’s what it does without a support structure. ANYTHING that burns can power it. There IS no big pile of replaceables necessary for it’s operation. Electricity is an offshoot of the water production. So now where you need clean water, you also have power generation.
Ever given any thought to what exactly it takes to have always clean, always available water coming out of the tap? Ever thought about how you’d feel if you couldn’t trust it?
Dija know he sponsors High School kids learning robotics? (google Kamen and FIRST)
Kamen excells in creating truely new stuff, which mostly concerns with improving the human condition.
If you do a little digging, you’ll find VERY LITTLE he does is hype. I wish there were more folks out there with his ethics and record of successes.