For the first time on record, the average capacity factor of natural gas-fired, combined-cycle power plants in the United States exceeded that of coal-fired power plants in 2015, according to a report issued today by the U.S. Energy Information Administration (EIA).
Capacity factor measures the actual output of a power plant, expressing that measurement as a ratio against the plant’s nameplate capacity, which is the amount of power a plant can theoretically output if run continuously, without regard for outage requirements or market conditions.
The EIA report notes that while utilization of gas-fired plants has increased, utilization of coal-fired plants has declined. With an average capacity factor of 56 percent in 2015 (up from 35 percent in 2005), gas-fired plants barely edged out coal-fired plants, which had an average capacity factor of 55 percent last year.
The report suggests natural gas-fired power plants have a competitive edge over coal-fired plants because of the way the plants are operated. While coal-fired plants primarily rely on steam-driven generating units, natural gas-fired plants rely on a variety of technologies, operating either combustion or steam turbines, or combining these two technologies into a hybridized solution via combined-cycle operation. In 2015, combustion turbines accounted for 28 percent of natural gas-fired usage, while steam turbines accounted for 17 percent of usage. Importantly, combined-cycle technologies accounted for 53 percent of natural gas-fired plant operation during the same period.
The report also attributes increased utilization of natural gas-fired power plants to the low price of natural gas in recent years.