U.S. coal-fired plants have been converted to burn other fuels or replaced, especially by natural gas, as pipeline projects are completed to meet demand for natural gas in North America.
According to data from the U.S. Energy Information Administration (EIA), 121 U.S. coal-fired power plants were repurposed to burn other types of fuels between 2011 and 2019. Of those, 103 were converted to or replaced by natural gas-fired plants. At the end of 2010, the United States had 316.8 gigawatts of coal-fired capacity, but by the end of 2019, 49.2 gigawatts of this amount had been retired, 14.3 gigawatts had the boiler converted to burn natural gas and 15.3 gigawatts were replaced with natural gas combined cycle. The decision for plants to switch from coal to natural gas could be attributed to stricter emission standards, low natural gas prices and more efficient new natural gas turbine technology.
Two methods are used to switch coal-fired plants to natural gas. The first is to retire the coal-fired plant and replace it with a new natural gas-fired combined-cycle plant. The second is to convert the boiler of a coal-fired steam plant to burn other types of fuel, such as natural gas.
Between 2011 and 2019, owners of 17 coal-fired plants adopted the first method, replacing old coal-fired power plants with new natural gas-fired combined-cycle plants. These new plants have a total generating capacity of 15.3 gigawatts, and this is 94% more than the 7.9 gigawatts of capacity of the coal-fired power plants they replaced. The rise in capacity is a result of the advanced turbine technology installed in the new plants.
Over the same period, 104 coal-fired plants converted the steam boiler to burn other fuels, most commonly natural gas, but some were configured to burn petroleum coke (a refinery byproduct), waste materials from paper and pulp production or wood waste solids.
Coal-fired plants in the eastern half of the United States have been good for conversion because they have smaller-capacity units and most are over 50 years old. Of the 104 coal-fired plants in this age range, 86 have converted their boilers to burn natural gas, representing 14.3 gigawatts of capacity. Most have been converted to exclusively burn natural gas, but some can still burn coal. This allows the plant to burn whichever fuel is most economically efficient.
Alabama Power Co. was the utility with the most conversions between 2011 and 2019. It converted 10 generators at four coal-fired plants, and they comprised 1.9 gigawatts of capacity. The conversions took place between 2015 and 2016 and were completed to comply with the Mercury and Air Toxics Standards required by the U.S. Environmental Protection Agency.
More of these conversions are expected to take place as the plants face challenges related to emissions standards and low natural gas prices. The majority of the conversions are expected to take place in the Midwest and Southeast. The EIA has been notified of eight projects to build natural gas-fired combined-cycle plants. Five are under construction, and these plants will replace existing coal-fired plants.
Between January and early July, about 5 billion cubic feet per day of new natural gas pipeline capacity started operating in the United States. Several of these projects could increase the ability to deliver natural gas to meet rising demand in North America.
In late June, Tallgrass Energy completed the 70-mile Cheyenne Connector Pipeline and Cheyenne Hub Enhancement Project, adding 1.6 billion cubic feet per day of natural gas capacity. The projects span northeastern Colorado and to near the Wyoming border. In April, Cheniere completed the 233-mile greenfield MIDSHIP Pipeline, adding 1.1 billion cubic feet per day of natural gas capacity. The project runs from central to southern Oklahoma, near the Texas border. Three projects that connect the Waha hub in western Texas near Permian Basin production areas comprise more than 1 billion cubic feet per day of natural gas capacity. These three projects were completed in February, May and July.
While nearly 5 billion cubic feet per day of new natural gas pipeline capacity started operating in the first half of the year, almost 8.7 billion cubic feet per day of pipeline projects have been canceled in 2020. The South Central region had the most capacity canceled, at 3.5 billion cubic feet per day, with the cancellations of the Permian to Katy Pipeline and the Creole Trail Expansion Project 2.