Whether it be for everyday carry, outdoor adventure, or disaster preparation, flashlights tend to be found towards the top of must-have items. But one common aspect of these luminescent devices is that they're only as good as the batteries inside. If you've ever switched on a flashlight only to experience a flood of frustrated disappointment, you might appreciate owning an "eternal flashlight." Lumen is designed to be powered by body heat, never needing batteries.
Sunlight can be used to generate electricity either through a
photovoltaic effect, or by harnessing the heat produced by the light.
There are already hybrid systems that combine both, but scientists at
Korea's Yonsei University have now developed a type of hybrid setup that
they claim works better.
While many of us may enjoy grilling food over an open fire, the fact is that cooking fires are a major source of health problems for millions of people in developing nations, who use them on a daily basis. The main problem is the smoke, which causes respiratory problems – not to mention air pollution. In an effort to address the problem, research group RTI International has developed a cook stove that burns cleaner … and that powers gadgets.