In 2018, 138 gigawatts (GW), or 13%, of the total operating electric generating capacity within the United States is made up of generators capable of switching between natural gas and petroleum liquid fuels, according to the U.S. Energy Information Administration’s (EIA) most recent annual survey of electric generators. Fuel switching refers to a generator’s ability to completely but temporarily replace one generation fuel source with another.

The ability to switch fuels is functionally beneficial for a generator because it allows the generators to use a less expensive fuel, reducing operating costs and improving its competitiveness. During extreme cold weather events or other supply disruptions, residential and commercial customers may use local natural gas supplies to meet increased heating demand, resulting in higher fuel prices or curtailed service for electricity generators.
For most fuel-switching generators in the United States, the primary energy source is natural gas and the secondary fuel is distillate fuel oil or residual fuel oil. Other secondary fuels include kerosene, jet fuel, and waste oil.

Most fuel-switching applications are natural gas combined-cycle systems (48 GW) or natural gas combustion turbines (57 GW) that were built after 1990 and are more likely to switch to distillate fuel. Fuel-switching applications that use natural gas steam turbine technology (33 GW) were mostly built before the 1980s and tend to use residual fuel as their secondary source.
Most fuel-switching generating capacity in the United States is located in states along the East Coast. Florida has the most fuel-switching capacity: the state’s 27 GW of fuel-switching capacity accounts for 47% of the state’s total capacity.
Most of Florida’s fuel-switching capacity is within the Florida Power & Light balancing authority. West County Energy Center, which has three natural gas-fired combined-cycle blocks that total 3.7 GW, is the nation’s largest power plant capable of switching fuels. Florida’s peninsular geography may contribute to natural gas delivery constraints if pipelines are filled to capacity or disrupted.
Extreme weather events such as the 2018 bomb cyclone and the 2014 polar vortex have demonstrated the importance of fuel switching in maintaining electricity reliability in the Northeast. The New York Independent System Operator (NYISO) has 16.3 GW of capacity that are capable of switching fuels, including the 2.3 GW Ravenswood facility, the nation’s second-largest fuel-switching facility.
The New England Independent System Operator (ISO-NE) has a natural gas and petroleum fuel-switching capacity of 8.3 GW. ISO-NE’s fuel-switching capacity is important because of its location at the end of several natural gas pipeline networks and because of the region’s competing demand for natural gas as a heating fuel in the residential and commercial sectors.