What did you do when the sun went down? If you’re reading this, chances are you switched on a light. But for the 1.3 billion people around the world who lack access to electricity, darkness is a reality. There is no electric light for children to do their homework by, no power to run refrigerators that keep perishables or needed medicine cold, no power for cooking stoves or microwaves. What light they have mostly comes from the same sources that humans have relied on forever–firewood, charcoal or dung–and the resulting smoke turns into indoor pollution that contributes to more than 3.5 million deaths a year. “For us, life does not stop after dark,” says Michael Elliott, president and CEO of the development nonprofit ONE. “For 550 million people in sub-Saharan Africa and many more than that around the rest of the world, it does.”