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."

Re:80 US gallons

[kurokame]

Longer, if they don't like their kids much.

Re:Damn you, science jornalism.

[wagnerrp]

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.

Exactly. The panels and pump are probably going to last several years without significant maintenance, but they will need a steady supply of filters to keep the thing going. They could extend the lifetime of them by running them in reverse for some amount of time to clean them out, but you can't do that indefinitely, and the system isn't usable while being back-flushed.

Sigh...

[SmallFurryCreature]

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?

Re:Boats

[rmccoy]

Small reverse osmosis systems have been available for personal cruising boats for years. From units powered from the 12 volt battery system down to hand-pumped emergency units.

Longevity and Recreational Marine Use

[JimMcc]

The photo of the unit shows what appears to be a Clark Pump as used in Spectra Watermaker systems. (http://www.spectrawatermakers.com [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.

Solar PV?

[Eclipse-now]

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" [vestergaard-frandsen.com] 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 [watercone.com] 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.