GravityLight

thumb GravityLight was a gravity-powered lamp manufactured until 2019. It was designed by the company Deciwatt for use in developing or third-world nations, as a replacement for kerosene lamps. It uses a bag filled with rocks or earth, attached to a cord, which slowly descends similar to the weight drive in a cuckoo clock. This action was claimed to power the light for up to twenty minutes. The design never proceeded beyond a limited number of early prototypes which did not appear to be practically usable by many consumers, and the company announced a change of direction in 2020.