Solar Oven

[Whitney]

I thought this was pretty cool...well, hot.

$6 Solar Cooker Wins $75K Climate Change Prize
by Yuka Yoneda

Think humankind discovering fire was revolutionary? How about a cardboard box that uses the sun’s rays to cook without burning firewood? That’s precisely what the Kyoto Box, a cardboard solar cooker, can do. Made out of basic, 5th-grade-science-experiment type materials, the Kyoto box solar cooker offers a life-altering solution for thousands of people: the ability to cook and heat water without burning wood. So how does it work? Inventor John Bohmer says the box uses “the greenhouse effect for something good.”

The Kyoto Box consists of two cardboard boxes, one which Bohmer’s own 5-year-old daughter helped him paint black, and another covered with tin foil to help concentrate the sun’s rays. A plexiglass cover is used to trap heat inside making it possible for the box to boil and bake, but not fry, so it is arguable that it is healthy as well.  The Kyoto Box is already in production at a factory in Nairobi, and Bohmer hopes to offer a the box in a recycled plastic form in the future. The cost of the box will be a mere 5 euros.

The idea for the Kyoto Box came from Kenyan-based inventor John Bohmer’s desire to create a cooking apparatus that would eliminate the need to burn lumber, which not only leads to deforestation but also emits harmful CO2. Judges of Forum for the Future’s Climate Change Challenge were certainly impressed by the ability of the box to alleviate global warming issues, but were even more keen on the what the Kyoto Box could mean to parts of the world where finding lumber to cook with and clean water to drink is an everyday struggle.

Pictures are available if you follow the link:  http://www.inhabitat.com/2009/04/10/kyo ... challenge/

[curiosityandthecat]

Wow. Imagine the implications for humanitarian aid.  

[karadan]

I love it when people think out of the box.

 

[SallyMutant]

Hey, kids, there are lo-tech solar things you can try at home. This thread has inspired me to re-do, during the hottest part of this summer,  what we did while living in a small storage building, rigged  for cold-water only, while our "Real house" was getting ready.
Place lots of full, rinsed gallon plastic milk bottles in the sun.  Have a warm "shower" nekkid in your backyard. This does depend on your backyard foliage/privacy. Or your  attitude toward neighbors.

[AlP]

This got me thinking about applications for solar ovens. I have this silly idea that I will attempt to explain with a diagram. The idea is to use sunlight to generate electricity by boiling water with solar ovens floating in a flooded greenhouse, condensing it with a heatsink once the water vapor has risen and then extracting the potential energy using a turbine generator. It's like a miniature enclosed hydroelectric dam. I'm sure I'm breaking conservation of energy or some rule of thermodynamics. Can someone please put me out of my misery and tell me why it doesn't work? I think it probably has something to do with it being a closed system.

[templeboy]

AlP, your idea doesn't break any physical laws- however one suspects that it would be impractically inefficient.

[Ayreon]

It would have to be fairly large to generate enough energy to be profitable.

[SSY]

I have tried these, cooking in them is somewhat ambitious, though they could do things like speed up the distilation of water etc, then again, I live in England.

Also Alp, your idea is fine from a thermo point of view, but I think it would be a lot more efficent to just put a massive solar cell there or those towers that collect sunlight and boil water to make steam.

[Heretical Rants]

Can someone please put me out of my misery and tell me why it doesn't work?

It's not a closed system: light goes in, heat goes out...


It works, but it's extremely inefficient because it takes enormous amounts of energy to boil such large quantities of water, and you're essentially throwing heat away with that design.

I suggest you use steam, rather than gravity
Don't shy from steam power.  It works and it works well.

Also, the "floating solar ovens" are entirely unnecessary.
Take out the turbines, and you have a decent solar water distiller.  Almost.  The clean water would run down the wrong side and back into the dirty water!

[AlP]

Also Alp, your idea is fine from a thermo point of view, but I think it would be a lot more efficent to just put a massive solar cell there or those towers that collect sunlight and boil water to make steam.

Hell I'm amazed it would work at all! The turbine isn't drawn to scale I guess =). This idea appealed to me because its something I could actually build myself on a small scale, minus the turbine. Although I did build a motor once and I guess a turbine is basically a motor working in reverse.

Also, the "floating solar ovens" are entirely unnecessary.

Lol. This was my unscientific approach =). I imagined a flooded greenhouse and saw no steam. It didn't reach boiling point. Then I imagined dropping in floating solar ovens with insulation to allow the submerged contents to get hotter than the surrounding water and sufficiently small to reach boiling point. Then there was lots of steam (imaginary steam that is). What do I need to read to know how this stuff works?