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."

80 US gallons

[MichaelSmith]

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.

Re:80 US gallons

[afidel]

FTFA 24 of them will fit on a C130 and provide water for "more than 10,000 people", so I'm thinking more like 500 people per large unit and that's under ideal conditions. That's as opposed to a more traditional [usbr.gov] unit about the size of a cargo container that can do 200k gallons a day or enough for 40-50k people. Personally I think for large scale disasters it makes a LOT more sense to drop 2 of those and two fuel/generator sets and supply 10x more people with fresh water since every cargo flight counts.

Try it

[Anonymous Coward]

See how long those panels remain attached once the "disadvantaged" figure out what they are worth.

Re:Boats

[TooMuchToDo]

Most commercial vessels (cruise ships, cargo/oil tankers, etc) already use evaporative systems (waste heat from engines/generators is used to flash heat water to steam, which is than condensed back into clean drinking water). A possible market would be smaller yachts and sail boats that sail around the Caribbean.

Re:Question

[L4t3r4lu5]

More's the point, why the hell isn't their a manual pump? You don't need sunlight to hand-crank a piston. Some form of centrifugal brake* will prevent exceeding the maximum pressure of the filter, and it can run indoors with a hose out to the salt water.

* - I don't know if this is the correct term. The faster you turn the crank, a set of weighted brake shoes (or similar) move out towards a high friction surface. The faster you spin, the harder it becomes to continue. Or some such.

Re:Question

[Biogenesis]

Here's a quick and dirty stab at some calculations:

Wikipedia claims that reverse osmosis requires 6kWh to produce 1000L of water, or 21.6 kJ/L.

To evaporate water already at 100C requires ~41kJ/mol, or 2.3kJ/L. To heat 1L of water from 20C to 100C requires 33.6kJ. So, by this very simplistic model it would require ~34kJ/L to desalinate water by boiling.

Now the efficiency of PV vs thermal in a solar powered system depends on the efficiencies of the collectors. PV is ~25%, at best, solar insolation -> electricity. Heating water to evaporate it is a much more difficult calculation. Basically water doesn't have to be at 100C to evaporate and the losses in a thermal system would increase as the temperature differential (system->ambient) increased but in the end I'm not really educated enough to comment accurately. Hopefully the numbers above will give you some feel for the problem though.

Re:Damn you, science jornalism.

[drinkypoo]

This is precisely what I was thinking. The water filter is neat but it is NOT solar-powered. It is electrically powered, and it is in this case coupled with a solar system which provides the power to operate it. I was excited because I would like a better, cheaper solar-powered desalinator.