U.S. natural gas-fired combined-cycle (NGCC) capacity has surpassed annual and monthly coal-fired electricity generation capacity, according to the Energy Information Administration (EIA).

EIA said on Wednesday that the amount of generating capacity from natural gas-fired combined-cycle (NGCC) plants surpassed coal-fired plants in 2018 as the technology with the most electricity generating capacity in the United States.

As of January 2019, U.S. generating capacity at NGCC power plants totaled 264 gigawatts (GW), compared with 243 GW at coal-fired power plants.

Total capacity for generating power in the United States across all types of natural gas-fired generating technologies surpassed coal as the primary capacity resource more than 15 years ago. However, different natural gas-fired generating technologies are used differently.

Combined-cycle units heat up fuel and use the fuel-air mixture to spin gas turbines and generate electricity. The waste heat from the gas turbine is used to generate steam for a steam turbine that generates additional electricity.

As of the end of 2018, NGCC power plants accounted for about half of all U.S. natural gas-fired generating capacity, but they provided almost 90 percent of total natural gas-fired generation.

“Capacity factors for NGCC plants, which reflect their actual output as a percentage of their capacity, are nearly equivalent to those of coal plants and are typically in the 50 percent to 60 percent range, while natural gas combustion and steam turbines are much lower at about 10 percent,” EIA stated.

It is worth noting that, since the beginning of 2015, about 40 GW of coal-fired capacity retired and no new coal capacity came online in the U.S.

During that same period, NGCC net capacity has grown by about 30 GW. The electricity generation from these NGCC capacity additions as well as output from new wind and solar generators has largely offset the lost generation from coal retirements.

To remind, electricity generation from NGCC power plants first surpassed coal-fired generation on a monthly basis in December 2015 and again in the first half of 2016 during times of relatively low natural gas prices.

Higher natural gas prices reversed the crossover until February 2018 when NGCC generation again surpassed coal generation.

EIA said in its most recent Annual Energy Outlook that, as more NGCC plants come online and coal plants continue to retire, NGCC-powered electricity generation should consistently rank as the most prevalent source of electricity generation in the U.S. for the foreseeable future.