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Solar stills
"Some have predicted that, as with oil, the world will face drinking-water shortages in the coming decades. Dean Kamen, inventor of the Segway scooter, has come up with a system, based on a Stirling engine, that can create potable water. "

I'm betting on solar stills, Read the thread on "solar stills" (it starts at the bottom of the page and works up):
http://nigeljohnstone.com/

The claims for current solar stills are that they're 60% efficiency but thats rubbish, thats the percentage of energy they collect to boil off the water. But boiling off the water isn't the intent of a solar still. The intent of a solar still is to boil AND RECONDENSE the water.

Crunch these numbers: if you start with pure water, heated it, boiled it off, condensed it, cooled it down and collected all the energy involved in that conversion in a 100% efficient system then you would use 0 joules. Nothing, zero.

If you did the same with salt water you would use energy because the energy to boil salt water is more than the energy to boil pure water, so when you condense the pure water you get less energy back than the boiling of the salt water.

But overall its very small. I was quite amazed when I crunched the numbers.

1m2 of surface normal to the sun, is enough make 1 litre of 100 degrees C water in 5 minutes near the equator.

So with a solar still I can turn seawater into freshwater, not just impure water.
Posted by: Nigel Johnstone   Posted on: 10/24/05 You are currently: a Guest | Members login | Terms of Use

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Solar stills  Nigel Johnstone | 10/24/05

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