Natural gas-fired generation, the backbone of U.S. electricity generation, varies by region
Energize Weekly, February 28, 2024
Natural gas generation is the largest source of electricity in the U.S. and is used across the country, but the scale and efficiency of that generation varies region by region, according to an analysis by the federal Energy Information Administration (EIA).
In 2023, natural gas accounted for 43 percent of electricity generation, and utilities added nearly 9.3 gigawatts (GW) of new capacity. That was second largest additions last year after solar, which added 40 GW.
“Combined with increasing domestic supply and relatively low natural gas prices, the versatility of natural gas-fired power plants to meet a wide range of requirements across many U.S. markets is one of the main reasons for their growth,” the agency said.
However, the efficiency, ability to ramp up quickly, so-called dispatchability and the share of generation natural gas plants have varied significantly by region. “Decades of advancements in natural gas turbine efficiency mean that the age of natural gas-fired plants affects how those plants are used,” the EIA said.
There are four basic types of technology, which dictate efficiency and offer flexibility: combined-cycle gas turbines (CCGT), simple-cycle gas turbines (SCGT), steam turbines (ST) and internal combustion engines (ICE).
In 2022, CCGT plants made up the largest part of the natural gas fleet, 58 percent, followed by SCGT, 26 percent, ST, 15 percent and ICE, 1 percent.
CCGT plants are highly efficient, allowing them to generate low-cost power over extended periods, enabling them to be used for base and intermediate loads.
The three other plant types are used mostly to meet peak demand on the electric grid and run less frequently. “These three sources can start and ramp up to full power quickly, which is critical in markets with an increasing concentration of intermittent renewable generation,” the EIA said.
Of the 9.2 GW of new capacity added in 2023, 80 percent was CCGT and a little less than 20 percent was SCGT. There were also 142 MW of ICE plants added.
CCGT plants, with higher efficiency, typically run more than half of the time and had a fleetwide capacity factor of approximately 56 percent in 2022. The newest plants – those placed in service since 2014 – have a capacity factor of about 66 percent.
The average capacity factor for the oldest plants – which went into operation between the early 1980s and 1989 – is only 36 percent.
“SCGT, ST, and ICE natural gas-fired generating facilities all had average capacity factors below 20 percent in 2022 because they usually are only called on to operate when power demand is at its highest or when intermittent renewable energy sources need backup,” the analysis said.
All 11 major electricity regions depend on natural gas to provide a substantial amount of their power load ranging from 73 percent, 46.5 GW, for the Florida Reliability Coordinating Council to 23 percent, or 24.8 GW, in the Pacific Northwest.
The regions with the largest concentration of natural-gas fired capacity are in the eastern half of the U.S. where natural gas production from shale and tight geological formations in Pennsylvania, Ohio and West Virgnia has increased in the last 10 years.
“Natural gas production growth from the Marcellus shale region has boosted natural gas generation in PJM, the Midcontinent Independent System Operator and parts of SERC,” which covers the Southeast and the South, the EIA said.
Natural gas-fired capacity in the Electric Reliability Council of Texas also has been bolstered by increased natural gas production in that state.
The capacity factors also differ markedly from region to region with the Southeast CCGT plants posting an average 70 percent capacity factor, while those in the Independent System Operator-New England have an average of about 40 percent.
