A total of 121 U.S. coal-fired power plants were reused to burn other types of fuels between 2011 and 2019.

Of that total, 103 were converted or replaced by natural gas plants, the Energy Information Administration (EIA) reported.

At the end of 2010, there were 316.8 gigawatts (GW) of coal-fired capacity in the United States, but by the end of 2019, 49.2 GW of that amount was retired, 14.3 GW had the boiler converted to burn natural gas, and 15.3 GW were replaced by natural gas combined cycle.

The plants’ decision to switch from coal to natural gas was driven by stricter emission standards, low natural gas prices and new, more efficient natural gas turbine technology, according to the EIA.

Coal-fired power

In general, two different methods are used to change coal plants to natural gas.

The first method is to remove the coal-fired power plant and replace it with a new natural gas combined cycle plant (NGCC).

Meanwhile, the second method is to convert the boiler of a coal steam plant to burn other types of fuel, such as natural gas.

Between 2011 and 2019, the owners of 17 coal-fired power plants adopted the first method, replacing the old coal-fired power plants with new NGCC plants.

The new NGCC plants have a total generating capacity of 15.3 GW, 94% more than the 7.9 GW capacity of the coal-fired power plants they replaced.

The increased capacity is largely the result of advanced turbine technology installed at NGCC plants.

During this time period, 104 coal plants took the second approach, converting the steam boiler to burn other fuels, most commonly natural gas, although some were configured to burn petroleum coke (a refinery by-product), waste materials from paper and pulp production, or solid wood waste.

Coal plants in the eastern half of the country have been good candidates for conversion because they tend to be smaller capacity units and are mostly over 50 years old.