In the U.S. and other countries today, the coal industry has come under siege from both regulators and environmentalists. It has also become a regular talking point among politicians who either raise it as a jobs issue or as a climate change/public health flashpoint. Yet coal has always been and is today a staple in the world’s energy diet. It’s abundant and relatively cheap. About 40 percent of today’s power generated in the United States is still produced in coal-fired plants.