The coal fleet has been the backbone of the U.S. electricity supply system for decades because the fleet is critical to maintaining affordable electricity prices and a reliable and resilient electricity grid. Currently, the fleet is responsible for supplying roughly one-third of U.S. electricity needs.  Also, the coal fleet provides baseload electricity on a 24/7 basis.  At the beginning of 2017, the coal fleet was comprised of more than 900 electric generating units.  These electric generating units are responsible for providing electricity to consumers in 48 states.