Lighting is something that we take for granted in the developed world, but there are still many areas around the globe where people lack reliable access to light at night. Around one-fifth of the world’s population has no access to electricity. They often use kerosene lamps, which contribute to indoor pollution and have to be refilled with oil regularly. Also they are bad for the environment and human health. To solve this problem, an engineering start-up called SALt(Sustainable Alternative Ligh...

Old laptop batteries still have enough life in them to power homes in slums, researchers have said. An IBM study analyzed a sample of discarded batteries and found 70% had enough power to keep an LED light on more than four hours a day for a year. Researchers said using discarded batteries is cheaper than existing power options, and also helps deal with the mounting e-waste problem. The IBM team created what they called an UrJar, a device that uses lithium-ion cells from the old batteries to ...