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MIT Unveils Portable, Solar-Powered Water Desalination System
An anonymous reader writes "A team from the Massachusetts Institute of Technology's Field and Space Robotic Laboratory has designed a new solar-powered water desalination system to provide drinking water to disaster zones and disadvantaged parts of the planet. Desalination systems often require a lot of energy and a large infrastructure to support them, but MIT's compact system is able to cope due to its ingenious design. The system's photovoltaic panel is able to generate power for the pump, which in turn pushes undrinkable seawater through a permeable membrane. MIT's prototype can reportedly produce 80 gallons of drinking water per day, depending on weather conditions."
Thats 300 liters. Maybe enough for ten people if you are careful. Or a hundred people if you only need drinking water to keep them alive.
http://michaelsmith.id.au
Pump-fed nanofilters are sort of an old idea at this point. The summary leaves off some critical points like how much it costs and how long the filter lasts.
According to the article, it costs $8000, which is a lot for some things but probably accessible for others. Let's just say it's not going to solve the world's water problem overnight, but it might be handy for relief efforts.
Surfing through to the parent MITnews article, we get a bit more information, but it's still lacking anything about how long the system can operate or what its maintenance costs and requirements are. Does it last a week then you're out most of another $8000? Does it require a lot of technical expertise to maintain? It doesn't say...
While this design is a step up, and it certainly must have been a great engineering challenge to build and integrate, there is no groundbreaking technology that goes into this. It's a simple reverse osmosis plant, based on technology that's already being used at commercial scale. The summary is also misleading - this system also requires a lot of energy, it just has a power source with it. In fact, it's almost certainly less efficient than a conventional RO system, both in terms of energy used and embedded energy in the solar panel and equipment used up over the equipment's lifetime. Bravo for making it modular, but what went into it is pretty clearly old news.
And for about 8 more dollars, they could attach a big funnel and bucket for those days when it rains and the solar part doesn't work so well.
The obvious issue here is cost. But if they can get it low enough, they could sell this virtually anywhere to private residents, and I don't mean just 3rd world countries. Think about places like Australia where they frequently don't have enough water.
To get the price down, they need production of this. One simple way to do that, is to adopt it to boats in the western world. By doing this, the boats will be able to have clean water on-board available from offshore. Then as production increases, the costs go down. Then it allows these units to be produced CHEAPLY.
I prefer the "u" in honour as it seems to be missing these days.
See how long those panels remain attached once the "disadvantaged" figure out what they are worth.
Can someone comment on the comparative efficiencies of photovoltaic and solar thermal sources of energy? How much better is this really than using thermal-driven evaporative desalination? I mean, other than lacking in the "new and cool" factor
"Politicians and diapers must be changed often, and for the same reason."
arched over it and you get purified, distilled H2O dripping own the clear plastic dome.
You don't need to hail this as revolutionary.
You can apply the principle to a pool, pond or lake full of water (better is its running water since oxygenation helps keep moss down.)
Paint the bottom or float a black pan below the surface and you can get solar evaporation.
The arched cover can be designed with ribs in it to carry the water down.
MSBPodcast.com The opinions expressed here are my own. If you don't like 'em... Think up your own stuff.
Man, that brought back memories!
I built my first solar still in 1966 with a black garbage bag, a washed 3lb. coffee can, 4 ft. of aquarium air tubing, two rocks, and an Army surplus entrenching tool, as a Cub Scout.
I'd guess that if I could do this from a rough sketch and a basic explanation of how it worked as an 8 year old kid, then a community with adults could also manage.
Down With Slashdot BETA!!! I've been around the corner and seen the oliphant; you can only abuse me from your perspecti
A lot of these stories make the news not because of their validity, but because they're MIT.
The headline idea has a lots of flaws. For $8000 you can dig a well and install a pump that can supply the water for 250 people. Not only that, you'd have enough money left over to either cover any repair costs for a long time or to put towards another pump. A lot of African villages already have problems with more complex electric pumps, not being able to afford to pay for maintenance so the pumps sit inactive. This desalination plant will have the same issue but with the added expense of filters.
How often do you need to replace the filter? 300litres of salt water means 10kg of salt that presumably is stopped by the filter so it would quickly clog up and have to be rinsed several times a day. More problematic are the 450g of other impurities the filter would pick up that may not wash out. I can't see a filter lasting long.
My god man, your bladder must be made of steel.
Or are you that alienated from the real world that you think people in disasters zones first priority is a daily long hot shower and flushing toilets?
Yes, we use a LOT of water in the west because... well because we can. When the shit hits the fan, 3-5 liters a day can and must be enough. And that is actually a rather liberal amount. Enough to drink, do some cleaning and cook. No it won't give you a life of comfort but guess what, it isn't. It is disaster relief. Not disaster go away. That comes when the normal systems are replaced. If they ever were there in the first place.
You do know that some people have to carry their water for miles by hand? Do you REALLY think these people carry 30 liters a day for every person? What next, you are going to complain a disaster relief food package doesn't contain Ben & Jerry icecream and that just won't do? Entitled, you sure seem to think you are.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
Is reading that hard? DISASTER relief. You can't go around digging wells in a hurry. This system is designed to be put aboard an aircraft and flown to a disaster zone in a hurry to be used until normal operations can be resumed.
It is NOT a permanent solution.
Maybe if you could grasp this from the summary YOU could have gone to MIT and wouldn't be so upset.
What really is so hard to understand about the difference between disaster relief techonology and permanent solutions?
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
just kidding. great idea. could save many of us?
Sorry, but this just looks like a bog-standard boat desalinization system hooked up to some solar cells. I fail to see what is so earth-shattering about it.
We could solve a lot of problems by teaching people like you to think of big-picture logistical issues associated with real-world problems instead of jumping on the "lets bash this guy for being 'wasteful' so we can feel better about how 'socially conscious' we are" bandwagon.
30L/day/person isn't unreasonable at all for a disaster relief scenario--if anything, it might be on the low side. I know it makes you feel good to assume GP is talking about luxuries of washing cars and green lawns and long hot showers, but if you're going to try to bash him on the grounds of "not thinking about what the people really need" you really need to think outside the box of "how much water do I drink in a normal, sedentary, climate-controlled day?"
Remember, this device is planned for use in disaster relief operations. You have a lot of things to worry about, like:
Drinking water - When you have a disaster on the scale of Haiti, Katrina, etc. you're going to have a lot of people who have been trapped or otherwise isolated from fresh water, and are severely dehydrated. You will also have rescue and medical workers performing very strenuous physical activity, quite possibly in very hot and humid conditions. People like these are going to need a lot more than the "three liters a day" that some other posters have mentioned. I don't know how much experience you have doing that kind of work, but I've done some disaster cleanup and first responder work in hot and humid locations. I once went through over a gallon of water (about 4L for you metric types) on a single extrication call on the side of the highway in mid-July. All we did was pull the guy out of the car, board and collar him, take vitals, and put down absorbent pads to soak up spilled gasoline, and just doing that took a full gallon to get rid of dehydration symptoms--and I'd been well-hydrated before that point.
Cooking - In a major disaster relief effort, you'll probably see field kitchens preparing basic staple foods. Many of those foods, like rice, require clean water for preparation. You'll also need water for cleaning the cooking equipment.
Cleaning - You need clean water if you're going to be cleaning things. I'm not talking about luxurious hot showers or keeping new SUVs sparkling and shiny. Instead, I'm talking about the basic handwashing, bathing, and hygiene habits that help prevent the spread of some really nasty diseases. Or the laundering of field hospital linens and steam sterilization of surgical instruments, or irrigation of wounds to flush out debris. Or washing off days of accumulated mud, dirt, and other nastier things from people that have been trapped in buildings, or those who helped pull them out. You also have to account for some amount of vehicle cleaning and maintenance; the helicopters, aircraft, bulldozers, trucks, and other equipment do need to at least have dirt and mud washed off on occasion so they can continue to function, and except for a few special cases, you can't really do that with salt water--you'll corrode them out very quickly.
Also, bear in mind that it is sound engineering planning practice to provide some form of margin in an estimate. If you're planning for a disaster relief scenario, you don't base your plans on the absolute minimum of supplies needed for survival when things are functioning normally. Instead, you add margin to account for spillage, leaks, mechanical trouble, evaporation, and so on. It's far, far better to have extra water available than not enough.
So next time, give the poster the benefit of the doubt and try to examine his post before you accuse him of making assumptions and being narrow-minded.
The meek may inherit the earth, but the strong shall take the stars.
Is it just me or is this thing overly complex? Pumps? Solar Cells? Electricity? Why not just use the steam cycle? You have 3 reservoirs, One large one with cold salt water on the top, that feeds into a small reservoir that is heated to ~250D by a solar concentrator, steam from it is piped (insulated/non-thermally conductive pipeline) up to an enclosed area on the bottom of the large cold reservoir where it condenses back into water, the salt is left in the small heated reservoir until it is cleaned at night. It probably can't produce as much as MITs device & may require someone to check it every hour or so but its a LOT cheaper, probably $50-100, getting it to fit in a compact area for transport might be difficult but should be possible.
> MIT's prototype can reportedly produce 80 gallons of drinking water per day, depending on weather conditions.
I see it depends on a continuos supply of sunlight; but what if it rains for days in a row?
....The Third Worlders will quickly strip everything shiny off the systems and sell the metal to make a quick buck.
Not a prediction; reality. I've been there and seen it. Why do you think no-one really gives a damn about Haiti?
Regards;
What would be really impressive is a hydro-powered desalinization plant. Like you put salt water in the top and out the bottom comes fresh water, and the extract goes into a bucket which you can sell to saltwater aquarium enthusiasts.
If you are not allowed to question your government then the government has answered your question.
The photo of the unit shows what appears to be a Clark Pump as used in Spectra Watermaker systems. (http://www.spectrawatermakers.com) These are popular in recreation long distance sailboats as they require less power for a given output than traditional RO systems.
As for reliability and longevity, much depends on the design. If you keep pressures reasonable, and flow excess raw water back to its source, the RO membranes will last many years and thousands of hours of use. The key is not running pressures so high that the membrane gets clogged with solids from the raw water. Pre filtering the raw water also is critical to not fouling the membranes. We run a 30 micron then 10 micron filter before out high pressure pump. The prefilters only need to be changed when fouled so their life span depends on the turbidity of the raw water.
We live aboard our boat and run a watermaker instead of using shoreside water sources. The unit is not as energy efficient as the MIT units. We have used it for years, have over 500 hours on it, and it has had near zero maintenance. In cold water, currently seawater is about 48F, we get 15gph, at 55F+ we get 18gph which is the max rated output, and above that we need to run at lower pressures to not saturate the membrane. We can get greater throughput by adding additional membranes. Adding a second membrane would double our output. (Sorry for the non metric units.) The Clark Pump system will get lower output, but the longevity of the membranes should be comparable. Membrane prices vary, but are typically in the US$250-US$500 range.
The AC who keeps coming up with these "Duh this isn't complicated, all you have to do is $ridiculously_oversimplified_idea_that_wont_really_work" should give himself a name, like BadAnalogyGuy.
Maybe SimpleSolutionGuy or RedGreen.
"When information is power, privacy is freedom" - Jah-Wren Ryel
Isn't this what Dean Kamen made back in 1993, and has been trying to lower the production cost of ever since? (first demonstrated publicly in 2008 on Colbert) http://www.wired.com/wiredscience/2008/03/colbert-and-kam/
Need a second C-130 to bring down all the filters.
I don't know how many gallons a filter is good for and/or if they can be cleaned and recycled but it might prevent the practical deployment of these things.
I know a Brita pitcher filter is only good for about 50 gallons (different filter action I know).
The moment I read Solar PV I knew these guys had lost the plot. Why on earth do we need it to even have a pump, let alone moving parts and a costly Solar PV array to power it? If it's a big enough emergency, dump thousands of "Life Straws" into the field and let the wonder of the human mouth suck the water through the straw directly from the river, which filters it by the time it hits the lips. Solar PV? Are they trying to kill people by making this more expensive than it has to be? The Life Straw is also more flexible. People sometimes need to be on the move in emergencies. They can take their own Life Straw with them, and drink water from whatever river they find on the way.
There are also various bottle-filter versions that also use no power. They don't need it, as the hand cranks the water through the cleaning membranes.
There is also the Watercone, which again is portable, and can desalinate seawater with solar heat (but no Solar PV needed!) http://www.watercone.com/product.html But I guess when you work for MIT's space division and you have to reinvent something as basic as the wheel, one has to spend a million dollars to make a high tech space pen that will work in zero g rather than just use a pencil! The problem here, is we are talking about saving thousands of the world's poor. They can't afford the 'space-pen' version. (Or, more accurately, they can't afford the emergency relief agencies to have cost limit supply). Instead, lets dump thousands of Life Straws and Watercones, and let *people power* and sunlight provide the energy to save their own lives.