What does ‘clean coal’ mean and can it save the planet

In the developed world, we have been working on ever cleaner ways to burn coal since the first coal-fired generator began running in England back in the late 1800s. First, we moved away from burning coal inside our homes, concentrating the production of soot into a few large power plants and moving the soot plumes outside of cities. Then we began to make our smokestacks taller, so that pollution plumes would be lofted higher and distributed more broadly downwind of power plants. This reduced the immediate problem of inhaling soot, but generated the new problem of acid rain over large areas of the industrialized world.To deal with this new problem, we began outfitting our power plants with filters to retain particulates and scrubbers to trap the sulfur gases that were generating acid rain. The newest technological innovations go further, with one U.S. coal plant now able to capture CO2 and prevent its release into the atmosphere.Achieving cleaner emissions from the smokestacks of coal-fired power plants requires trapping ever larger quantities of coal combustion residues. These byproducts of coal combustion are one of the dirty truths about clean coal. The trace metals, sulfur, and carbon dioxide that are not being emitted to the atmosphere have to be disposed of. We have reduced regional acid rain problems through the concentration of coal waste into metal and trace element enriched fly ash and gypsum.