Demand for electricity will continue to increase as the economy grows.
Much of the projected increase in demand for electricity will be supplied by existing coal-fired power plants because they possess excess capacity that can be utilized at low incremental costs.  In order to meet the projected increase in demand for electricity, demand for coal by electricity generators is expected to increase through 2020.
Source: Energy Information Administration

Coal prices have historically been lower and more stable than natural gas prices.
While new natural gas-fired power plants generally are less expensive to construct than new coal-fired plants, we believe that the higher prices and volatility will continue to make natural gas a less attractive energy source than coal for many utilities, particularly for baseload electricity generation.
Source: Energy Information Administration

There is an abundant supply of coal.
Coal makes up approximately 95% of fossil fuel reserves in the United States, with an estimated 250-year supply of coal based on current usage rates.
Source: American Coal Foundation

Coal is increasingly less polluting.
As a result of improved technology and coal consumption trends to lower sulfur coal, sulfur dioxide emissions from U.S. coal-fired power plants have declined by more than 20% since 1970, even as coal consumption for domestic electric power has almost tripled.
Source: Coalition for Affordable and Reliable Electricity