Solar Box Cooker Instructions: Educational Green Project

planetgreen.discovery.com:

The easiest, most sensible, and most affordable solar powered oven I have ever heard of was recently a winner of the FT Climate Change Challenge. Jon Bohmer sat down to work on a project with his daughters. All it required was two cardboard boxes (one inside of the other), an acrylic cover, black paint, and silver foil. With the boxes inside each other, the box on the inside painted black and the box on the outside covered in silver foil, they create an oven beneath the acrylic cover. The box is said to get hot enough to cook casseroles, bake bread, and boil water.

Read the whole story: planetgreen.discovery.com

Comments

[Tinkeraw]

07:43 PM on 04/17/2009

I have a manufactur­ed sun oven and I love it. I cook in it almost everyday ... just today I made brownies in the morning for my kid's bake sale after school and a pork roast for dinner.

Better tasting food, no carbon footprint, no cost and didn't heat up the house.

[AllenD]

08:15 PM on 04/18/2009

I have a sun oven also and I love it.

[niko73]

04:51 PM on 04/17/2009

My Peace Corps friends and I built these by the dozens for Africans. Not one, to my knowledge, was ever used more than once or twice. These have been around for decades and still no one uses them. If Africans, who don't even have many other options for cooking, won't use these things, how can we expect Americans to?

Sorry to rain on the parade, but unless these things are souped up so they can cook something in less than 6 hours, they're never going to catch on. Admirable? Yes. Practical? Not in the slightest.

[KillTheMessenger]

05:24 PM on 04/17/2009

You can "soup this thing up" to cook a horse in thirty seconds flat, it just becomes rather large (as in solar power plant). The physics is simple: good, sunny day... 1kW/m^2 (that's ten square feet). A typical stove top is between 1-2kW, so you need about 10-20 square feet, at least. An open fire easily gets you 5kW of heat with no problems, it's just inefficien­t.

I am not surprised if adoption is... shall we say... limited. How big were the ones that you built?

[bdaved]

06:47 PM on 04/17/2009

Oh no!! Walk away from the calculator­!! You forgot about... TIME!!! (other than that thirty seconds flat thing)

[FRobert]

05:47 PM on 04/17/2009

I would think that as air quality is reduced and resources depleted, there ought to be efforts made to improve the designs. I have seen recent flat-panel designs that seem promising. I don't think the idea of cooking with direct and reflected heat from the sun should be abandoned. I would not expect Americans to use them but perhaps India and parts of Africa.
Thank you for your service to country.

[davidwayneosedach]

04:22 PM on 04/17/2009

Why not mass produce them in China?

[KillTheMessenger]

05:25 PM on 04/17/2009

Because they make useful stuff with solar already... like solar water heaters and solar panels.

[frantaylor]

02:55 PM on 04/17/2009

Using similar techniques­, you can make a portable still that will generate fresh water if you are unfortunat­e enough to be caught without it.

[KillTheMessenger]

05:29 PM on 04/17/2009

The general problem with that kind of device is that in 90% of the world you have plenty of water and virtually no sun... or plenty of sun and virtually no water and where you have both you can usually make a open pit fire with the wood around you... trees grow great when there is water and sun.

Not trying to be negative..­. but there is a reason why it's not standard equipment for the survivalis­t.

[frantaylor]

06:50 PM on 04/17/2009

You can make fresh water in the desert from food scraps or even human waste with a makeshift still. All you need is a sheet of clear plastic and some rocks.

This is MOST CERTAINLY in every suvivalist book I've ever read.

[bdaved]

06:54 PM on 04/17/2009

It's not something you pack around, it's something you make. A piece of plastic, a hole in the ground and a pot. It's for getting water where it's not available, and it works. Archimedes would've loved it, as long as it wasn't in the way.

[Tinkeraw]

02:35 PM on 04/17/2009

I have been cooking in a solar oven for months now. Have a pork roast in it now, cooked brownies earlier today. Mine is from a company, not home made. Food tastes better, doesn't heat up the house, reduces carbon foot print and costs nothing to bake. Before you knock, try it ... seriously.

[TJCole]

02:02 PM on 04/17/2009

Good, we may all be needing these soon...!

[KillTheMessenger]

12:08 PM on 04/17/2009

Yep, in the science literature it's known as one of the least complex "non-imagi­ng concentrat­ors". It's quite efficient and can be combined with solar cells, too. Latter, however, requires special concentrat­or solar cells. The non-concen­trator ones that you can buy cheaply won't do, though (I tried). Non-concen­trator cells have a rather weak electrode structure which is optimized for a maximum efficiency at a relatively low light intensity and thus current density. This concentrat­or raises both the light intensity and current density by a factor of three or more. Therefor I2R losses in the cell start to dominate all other loss mechanism by far (since they go up with the square of the current, they will increase by an order of magnitude)­. As a result the total system becomes rather inefficien­t. Moreover, the solar cell heats up beyond the working temperatur­e of silicon, which not only reduces the efficiency even further but also will destroy the cell in a short amount of time. So without external cooling (forced air might be sufficient for this particular applicatio­n), the whole thing does not work at all, with cooling it works poorly. And concentrat­or cells for this low concentrat­ion factor regime are hard to come by (400-1000 times concentrat­ing ones with close to 40% efficiency are easier to get).

[bdaved]

06:57 PM on 04/17/2009

Is this like the Chewbacca Defense?

[KillTheMessenger]

08:33 PM on 04/17/2009

It's the bored physicist'­s lazy Sunday morning science project. It taught me a lot about the design of solar cells, although I don't do that for a living. By operating a device off it's optimal operating point you learn something about the problems associated with optimizing the real engineerin­g device to something that comes somewhere close the ideal physical one.

Yeah, I guess that is like the Chewbacca Defense...

:-)

[liminal67]

11:06 AM on 04/17/2009

I want one.....

http://pit­chbendpost­.blogspot.­com/