Nearly 130 years after Thomas Edison created the first
marketable incandescent light bulb, nearly two billion people
around the globe still live their lives without a steady supply
of electric light. The problem is not light bulbs, of course,
but living off the grid. To generate light, these people do what
those without electricity have always done: burn something,
mostly kerosene. But kerosene is a dirty fuel: studies show that
breathing fumes from indoor kerosene use is the equivalent of
smoking two packs a day. The cost of producing light, when
compared to electricity from the grid in any American city, is
also astronomical: $3 to $11 per kilowatt hour. Aggressively
expanding the electric grid in Africa, Asia and South America
would solve the problem, but that is unrealistic, at least in
the near future. Yet there is another solution: decentralized
renewable electricity systems. For lighting, solar panels can
charge batteries and power conventional lamps. But there are
other solutions, too, like a solar li