Clay Moulton, a Virginia Tech student, has come up with a design with some serious environmental gravity.  An LED lamp powered by gravity to be specific.  This innovative design won him the  the runners-up honor at the Greener Gadgets Design Competition. 

The lamp, he dubs "Gravia" is powered by a falling weight.  The weight starts at the top of the cylindrical lamp and as it slowly descends it turns a highly efficient ball screw which spins the generator located at the base of the lamp, which in turn lights the LEDs.  This process take about 4 hours at which point it needs a little human power to get the weight back to the top.

He originally calculated that the lamp would produce 600-800 lumens (about a 40 watt bulb), but since winning the award there has been a lot of criticism that his calculations were not correct.  In a press release Moulton acknowledged that the currently state of the technology is not sufficient to make a working model.  But this is all part of the design process, and we look forward to seeing where this project goes. [via]