February 20, 2008 It’s the environmentally friendly lamp with gravitas. Clay Moulton, a Virginia Tech student, has created a 58-inch tall floor lamp powered entirely by gravity. Gravia uses a slowly sinking weight to charge 10 high-output LEDs, which fire into the acrylic lens and create a diffuse light output of 600-800 lumens, roughly equal to a 40-watt incandescent bulb.
The column contains five ten-pound brass weights that rest on a sled; when set in place by the user, they drift to the bottom of the lamp over the course of four hours. A high efficiency ball-screw converts the downward motion into torque, which is used to power a rotor. The rotor, housed in the base of the lamp, powers the light. The LEDs are activated only a few seconds after the process begins, and the entire operation is silent.
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Moulton said, “It’s more complicated than flipping a switch but can be an acceptable, even enjoyable routine, like winding a beautiful clock or making good coffee.”
If used for eight hours a day, 365 days a year, Gravia’s mechanisms will last for over 200 years. However, 10 to 15 years into their ownership, Gravia users can enjoy an interesting side effect. “As the acrylic ages, it becomes slightly yellowed and crazed through exposure to ultraviolet light,” Moulton said. “The yellowing and crazing will tend to mitigate the unnatural blue hue of the LED light. Thus, Gravia will produce a more natural color of light with age.”
Gravia won second prize at the Greener Gadgets Design Competition, which was judged by representatives from Endgadget, IDEO & The Designers Accord, and Inhabitat.
The first prize went to the EnerJar, a DIY kit that allows people to easily measure and monitor the energy output of their appliances, hopefully encouraging them to be more responsible with power use. Other notable entries included a plan to charge, swap and distribute green batteries through vending machines; a kinetically powered mobile phone; a charger based on elastic energy; and a method of harnessing the pedal power from exercise bikes.