A U.S. graduate student won second place in a “Greener Gadgets Conference” competition inventing a floor lamp powered by gravity.
The LED lamp, named Gravia, is an acrylic column a little more than 4 feet high. The entire column glows when activated by electricity generated by the slow, silent fall of a mass that spins a rotor.
The light output of 600-800 lumens lasts about four hours.
To “turn on” the lamp, the user moves weights from the bottom to the top of the lamp and into a mass sled near the top. The sled begins its gentle glide down and, within a few seconds, the LEDs are illuminated.
“It’s more complicated than flipping a switch,” said Moulton, “but can be an acceptable, even enjoyable routine, like winding a beautiful clock or making good coffee.”
Moulton estimates Gravia’s mechanisms will last more than 200 years.
A patent is pending on the Gravia lamp.
Source: Physorg
From the CRC reference book:
1 watt = 680 lumens is the maximum effeciency possible for production of light energy.
Assuming the gravia lamp operates at one watt to produce the claimed 600 - 800 lumens makes for an estamate of how long the lamp can operate. Placing 25 Kilograms of mass at the top and having it fall through a distance of 1.5 meters makes less than 400 joules of energy. here is the calculation:
mass * acceleration * distance
= 25kg * 9.8m/sec^2 * 1.5 meters
This would allow the lamp to run for less than 400 seconds or about 6 to 7 minutes.
the claim that the lamp would run for 4 hours is a fraud.