I really like an idea of gravity-based light, reminds me of a weight-driven wall clock we had as a kid. So it was somewhat sad to read that GravityLight has bee

I really like an idea of gravity-based light, reminds me of a weight-driven wall clock we had as a kid. So it was somewhat sad to read that GravityLight has been discontinued. This page has a nice, technical explanation: https://www.engineeringforchange.org/news/gravitylight-nowlight-startup-pivots-technology-improves/ https://www.engineeringforchange.org/news/gravitylight-nowli... In short, the cellphones got popular, but the gravity mechanism was only producing ~0.1 watt of electricity, which is not nearly enough to charge them.