Although the solar oven is an old idea, this new design won a $75,000 prize by holding off 300 other inventions that included a machine that turns organic material into charcoal, wheel covers that reduce a truck's drag, and a livestock feed supplement that reduces livestock's methane emission by 15 percent.
The competition was run by Forum for the Future (click the link for more on the competition) to encourage innovation to combat climate change. The winning entry consists solely of two cardboard boxes, a black painted one inside a foil lined one with an acrylic “window” on top. Incredibly simple and cheap to make ($5) it can still boil water, cook vegetables and bake bread in hotter countries. It can greatly reduce the need for people to walk many miles every day cutting and carting heavy loads of firewood and “deforesting” their neighbourhood. It can also be used to sterilise drinking water.