Solar ovens aren't a new phenomenon, but with the worldwide interest in alternative energy growing, new attention is being focused on them. NGOs are distributing them to impoverished villages where deforestation and desertification are a problem, and they're also popular in places where fire risk is extremely high (for instance, with campers inside particularly dry national parks). One interesting fact about solar cookers is that many of them use the greenhouse effect to cook food: solar rays are reflected and concentrated inside a glass box, which traps increasingly hot air inside. As the temperature builds, your food cooks, and even the humblest of solar ovens can reach 350 degrees in about 30 minutes. The main problem with these contraptions is that they function best during the hottest parts of the day -- when people are the least likely to want a hot meal. But a Colorado company has found an ingenious way to use the midday cooking power of the sun to their advantage: by roasting coffee.
Solar Roast Coffee has invented (and continues to refine) a specialized array of focusing mirrors, which swivel to follow the arc of the sun during the day, and can roast a drum of coffee beans at up to 600 degrees Fahrenheit. (You can watch it in action here.) The beans may be brown, but this is one green coffee.