Combined-Cycle Natural Gas Generators Are the Electric Work Horses

Tom Shepstone
Shepstone Management Company, Inc.

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The EIA details just how important electricity generation from combined-cycle natural gas plants really is to our economy and future.

The following post was authored by David Manowitz at the Energy Information Information (EIA). You can look at these stats and not realize just how integral natural gas is to electricity generation, our energy security, our economy and our future. It’s yet another marvelous summary of the facts illustrating how fracking and the shale revolution changed everything. So nice to find a bureaucracy that is productive in sorting out the facts!

combined-cycle

Source: U.S. Energy Information Administration, Annual Electric Generator Inventory

Based on the U.S. Energy Information Administration’s (EIA) annual survey of electric generators, natural gas-fired generators accounted for 43% of operating U.S. electricity generating capacity in 2019. These natural gas-fired generators provided 39% of electricity generation in 2019, more than any other source. Most of the natural gas-fired capacity added in recent decades uses combined-cycle technology, which surpassed coal-fired generators in 2018 to become the technology with the most electricity generating capacity in the United States.

Technological improvements have led to improved efficiency of natural gas generators since the mid-1980s, when combined-cycle plants began replacing older, less efficient steam turbines. For steam turbines, boilers combust fuel to generate steam that drives a turbine to generate electricity. Combustion turbines use a fuel-air mixture to spin a gas turbine. Combined-cycle units, as their name implies, combine these technologies: a fuel-air mixture spins gas turbines to generate electricity, and the excess heat from the gas turbine is used to generate steam for a steam turbine that generates additional electricity.

Combined-cycle generators generally operate for extended periods; combustion turbines and steam turbines are typically only used at times of peak load. Relatively few steam turbines have been installed since the late 1970s, and many steam turbines have been retired in recent years.

Not only are combined-cycle systems more efficient than steam or combustion turbines alone, the combined-cycle systems installed more recently are more efficient than the combined-cycle units installed more than a decade ago. These changes in efficiency have reduced the amount of natural gas needed to produce the same amount of electricity. Combined-cycle generators consume 80% of the natural gas used to generate electric power but provide 85% of total natural gas-fired electricity.

Combined-Cycle

Source: U.S. Energy Information Administration, Annual Electric Generator Inventory

Every U.S. state, except Vermont and Hawaii, has at least one utility-scale natural gas electric power plant. Texas, Florida, and California—the three states with the most electricity consumption in 2019—each have more than 35 gigawatts of natural gas-fired capacity. In many states, the majority of this capacity is combined-cycle technology, but 44% of New York’s natural gas capacity is steam turbines and 67% of Illinois’s natural gas capacity is combustion turbines.

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2 thoughts on “Combined-Cycle Natural Gas Generators Are the Electric Work Horses

  1. Great concept and very efficient. The good thing is that a good portion of Upstate NY Utility loads are located over prime Marcellus / Utica resources. Supporting the unit to be mounted and fueled directly on the site from the site. It would be great if the Department of Energy and local utility providers teamed up to implement this throughout Upstate NY. And its a reliable consent source.

  2. All this above information is true and STILL barely scratches the surface of what is unfolding with these CCGPs (Combined Cycle Gas Plants).
    These power stations are being increasingly pre-fabricated, shipped to remote locales, and then assembled onsite.
    Furthermore, the fuel (natgas) to power these generators has – historically – been restricted to areas where pipelines exist.

    No more.

    Employing inexpensive, quick to install Floating Storage and Regasification Units (FSRUs), locations such as the Indonesian archipelago, remote Philippine islands, Amazonian Brazil, and many, many more places/populations will soon enjoy inexpensive and reliable electricity 24/7.

    The ferocious pace of downsizing the cost to produce natgas (your Appalachian Basin operators are leading the way), construct LNG plants, even building/operating the ships used to transport the product ensures that American, Russian, and Qatari natgas will provide abundant fuel by which these CCGPs will provide electricity to a global audience for decades to come.

    This is still the early innings of this ‘Shale Revolution’.

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