Is Gravity-powered Light Possible?
Most recent answer: 04/10/2014
- Adam Contra (age 48)
Odessa, Ukraine
Your friend is no doubt concerned about where the energy comes from to power this light. The energy is supplied via the muscles of whoever lifts up the rocks etc. to put in the bag. Then that gravitational potential energy is gradually converted to (mostly) electrical energy as the bag slowly falls, driving the generator. The LED does an efficient job of converting a good fraction of the energy to light.
Your muscles get the energy from food or from stored body fat. Whether that's more convenient than carrying around some batteries depends completely on the situation.
What surprises me is that the site says the device cost $300,000 to develop. Small electrical generators and LED lights are standard inexpensive commercial products. A bag, a pole, some pulleys and gears don't seem like they would cost all that much to develop. Maybe that cost includes manufacturing and distributing the first 7000 units, in which case it sounds about right.
Mike W.
(published on 04/10/2014)