I know you all cringed at the word "bag," assuming it was plastic as I did, but it's not. It's like a tea cozy for your cooking pot, and apparently extremely effective because it traps the initial heat and continues the cooking process for up to five hours (like a crockpot, but without electricity). Apparently it's making a huge difference in Africa, where fuel shortages are likely and untended cooking pots are a danger.
I have heard of these. At one point I did a lot of research regarding lowering cooking energy, and found this idea intriguing. Similar to the old idea of putting your food "to bed" -- i.e., sticking the pot under a quilt for a while, or the Hay Box Cooker.
I have a thermal cooker, and would imagine they work similarly: great for rice, poaching, even bread making [kinda] but if you need any turbulence/browning in the cooking process, obviously wouldn't do. Can't burn the food, that's for sure!
Great idea in areas with limited energy sources for cooking.
I really like the concept of the Wonderbag, but I wonder;) if you could achieve similar results by transferring the cooking pot into a pre-warmed oven or an insulated cooler. I can see how the Wonderbag would come in handy when making homemade yogurt (when you are "incubating" the yogurt culture and milk mixture).
Agreed -- it might be redundant here, where we have ovens that are already well insulated. I also keep a baking stone in my oven, which holds heat quite well -- so you're probably right that just putting it in the oven might accomplish the same thing...
We also have these in The Netherlands, this is a video that shows how it works http://www.youtube.com/watch?v=E44z-uE4HMc&hd=1 (never mind the voice over).
I read in a magazine that you can make a 'hay box' yourself, by using styrofoam for example, or just old (woolen) blankets. Anything that insulates will work. It's a good way to recycle and save energy in the process!