Coal is a sedimentary rock that is readily combustible and is the largest source for electricity world-wide. It is also one of the most significant sources of carbon dioxide released into the atmosphere. Coal is extracted by mining and then pulverized and burned to heat a boiler. The steam from the boiler spins turbines, which generate electricity. Although electricity generation from coal has become more efficient and substantially cleaner in recent years and research is under way to discover new ways to sequester and reuse released carbon dioxide, the environmental impact of the mining of coal is significant in many areas. Additionally, coal is not a renewable resource, as there is a finite amount available for use.
In Missouri, 85 percent of electric power is from coal, in no small part because of the easy access to coal from both Kentucky and Western states with large amounts of coal production. Although purchased electricity is frequently from coal sources at WUSTL, the university stopped using coal in 1992 on the Danforth Campus and 2002 on the Medical Campus, switching over to natural gas.