Gravity-Powered Lamp Wins Green Props

The Greener Gadgets Conference has doled out a design award to a Virgina Tech student who proposes a lamp powered by gravity. The floor lamp has a 4-foot column, down which a weighted element slowly slides, turning a rotor as it goes. That rotation produces enough juice to power 10 LEDs that produce light equivalent to a 40-watt bulb. It takes about four hours for the weight to travel all the way down the column, after which the user lifts it back to the top to start the process all over again. Says designer Clay Moulton:

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.

UPDATE: Gadget Lab reader Colin Watters writes in to question the design's feasibility:

*The maximium theoretical efficiency of any light source is 100% which
equates to 683 Lumens/W. Even if we achieved that the lamp would still weigh
1.4 tons. *

They say it produces 800L for four hours. Lets say the LED is 100% efficient
at 683 Lumens/W so that 800L for fours hours needs 1.17W for 4 hours.

So energy required = 1.17 x 4 x 60 x 60 = 16848 Joules

Energy stored energy in the weight is..

PE = mgh

m = mass in Kg
h = 1.2 meters (four foot)
g = 9.8

so m= 16848/(9.8 x 1.2) = 1432 Kg

1.4 Tons

I'm afraid it looks nice but it's not worth a prize.

*Nice work, Colin!
*

— Rob Beschizza

Lamp lit by gravity wins Greener Gadget Award[SAWF]