The big idea that's "light on technology"

[Beverleyh]

A far cry from the usual tech-advancements, but utterly brilliant! Sometimes, it's the simple things that solve the biggest problems - enjoy!

http://www.youtube.com/watch?v=o-Fpsw_yYPg

[djr33]

That's pretty cool. Simple, but it works. The end result is interesting looking too, oddly similar to a light bulb.

[molendijk]

Faith in homo sapiens restored.
Thanks.

[traq]

I saw that last year. It's awesome.

[jscheuer1]

I think it's a great idea! And a sad commentary or a number of things, including the ubiquitousness of the discarded 1 liter beverage bottle.

By following the links I found another video where they were making banks of collectors from these bottles, enough to heat the hot water for a good sized building.