clean coal

Any technology that may mitigate emissions of carbon dioxide and other greenhouse gasses that arise from the burning of coal for electrical power.

(dated) anthracite (a cleaner burning variety of coal, which is usually hard and bluish, with fewer impurities; making it acceptable for uses needing cleaner coal)

(dated) coke (a coked version of coal, that has been cleaned of many of its impurities, making it acceptable for use in steel-making and other uses needing cleaner coal)