The problem is that the cheapest source of lighting for many poor communities is hazardous biomass fuels like kerosene. And unfortunately good alternatives like

The problem is that the cheapest source of lighting for many poor communities is hazardous biomass fuels like kerosene. And unfortunately good alternatives like solar may not be a viable option for everybody. Sure there are many parts of Africa with good infrastructure, but just because you are living in Africa in the 21st century does not mean you are now surrounded by power lines! The nearest power socket might be a few dozen or even hundreds of miles away. How are you going to get there and back? If you don't succeed in charging your battery today because of floods or storms, will you go without lighting? And there is also cost and access to credit to account for. The GravityLight is targeting $5 price point, whereas a basic solar charging pack in Uganda costs approximately $150 USD on finance [1]. Compared to batteries, GravityLight has no operating costs. It also does not degrade over time, lose charge when it is unused, or unexpectedly stop working when the battery runs out. This might be an important consideration for some. As for whether the device can produce adequate lighting. A candle or simple kerosene wick lamp will produce around 8 lumens of light output [2] compared with the 16 lumens of the GravityLight. So this is pretty good. Each community has different needs and circumstances. Providing people with more alternatives to kerosene fuel will allow them to choose the solution that is right for them. [1] http://www.fenixintl.com/uganda/ http://www.fenixintl.com/uganda/ [2] http://evanmills.lbl.gov/pubs/pdf/offgrid-lighting.pdf http://evanmills.lbl.gov/pubs/pdf/offgrid-lighting.pdf