Coal is a cheaper fuel source in the developing world, including India, where a worker carries coal to load onto a truck at a depot in Gauhati. India and other countries are building coal power plants to meet demand as its economy grows. (Associated Press)

Coal is a cheaper fuel source in the developing world, including India, where a worker carries coal to load onto a truck at a depot in Gauhati. India and other countries are building coal power plants to meet demand as its economy grows. (Associated Press)