Cheap energy in a bottle lights up Kenyan slums

NAIROBI, KENYA - JULY 27: (Filed) People in Kenyan slums are seen in Nairobi, Kenya on 27 July 2014. Some residents are taking old plastic bottles and adding a dose of water, bleach and sunlight and fitted into a hole made on a rooftop to create a new light source inside dank tin shacks. This innovative light source is being a cheaper alternative to electric light bulbs in slums and schools in Kenya. (Photo by Recep Canik/Anadolu Agency/Getty Images)