"Clean energy" includes energy efficiency and clean energy supply options, like highly efficient combined heat and power as well as renewable energy sources. Coal is considered a nonrenewable resource because it cannot be replenished on a human time frame. Many people believe there is no such thing as "clean coal."
The activities involved in generating electricity from coal include mining, transport to power plants, and burning of the coal in power plants. Initially, coal is extracted from surface or underground mines. The coal is often cleaned or washed at the coal mine to remove impurities before it is transported to the power plant — usually by train, barge or truck. Finally, at the power plant, coal is commonly burned in a boiler to produce steam. The steam is run through a turbine to generate electricity. (Source: EPA, Photo: dgmata/iStockphoto)