Gas-fired power plant

{{See also|Thermal power station}}

A gas-fired power plant is a type of fossil fuel power station in which chemical energy stored in natural gas, which is mainly methane, is converted successively into: thermal energy, mechanical energy and, finally, electrical energy. Although they cannot exceed the Carnot cycle limit for conversion of heat energy into useful work, the excess heat, ie the difference between the chemical energy used up and the useful work generated, may be used in cogeneration plants to heat buildings, to produce hot water, or to heat materials on an industrial scale.

{{See also|Gas turbine}}

File:Gateway Generating Station rectified.jpg, a combined-cycle gas-fired power station in California, uses two GE 7F.04 combustion turbines to burn natural gas.]]

File:GE H series Gas Turbine.jpg configuration, its highest thermodynamic efficiency is 62.22%]]

Industrial gas turbines differ from aeronautical designs in that the frames, bearings, and blading are of heavier construction. They are also much more closely integrated with the devices they power—often an electric generator—and the secondary-energy equipment that is used to recover residual energy (largely heat).

They range in size from portable mobile plants to large, complex systems weighing more than a hundred tonnes housed in purpose-built buildings. When the gas turbine is used solely for shaft power, its thermal efficiency is about 30%. However, it may be cheaper to buy electricity than to generate it. Therefore, many engines are used in CHP (Combined Heat and Power) configurations that can be small enough to be integrated into portable container configurations.

Gas turbines can be particularly efficient when waste heat from the turbine is recovered by a heat recovery steam generator (HRSG) to power a conventional steam turbine in a combined cycle configuration.{{cite web |url= http://memagazineblog.org/2012/07/01/efficiency-by-the-numbers/ |archive-url= https://web.archive.org/web/20130207053320/http://memagazineblog.org/2012/07/01/efficiency-by-the-numbers/ |url-status= dead |archive-date= 7 February 2013 |title= Efficiency by the Numbers |first=Lee S. |last=Langston |date= July 2012 }} The 605 MW General Electric 9HA achieved a 62.22% efficiency rate with temperatures as high as {{convert|2800|°F|°C|order=flip}}.{{cite press release |url=http://www.gereports.com/bouchain/ |title=Here's Why The Latest Guinness World Record Will Keep France Lit Up Long After Soccer Fans Leave |first=Tomas |last=Kellner |publisher=General Electric |date=17 June 2016 |access-date=21 June 2016 |archive-date=16 June 2017 |archive-url=https://web.archive.org/web/20170616021542/http://www.gereports.com/bouchain/ |url-status=dead }}

For 2018, GE offers its 826 MW HA at over 64% efficiency in combined cycle due to advances in additive manufacturing and combustion breakthroughs, up from 63.7% in 2017 orders and on track to achieve 65% by the early 2020s.{{cite press release |url= https://www.genewsroom.com/press-releases/ha-technology-now-available-industry-first-64-percent-efficiency-284144 |title= HA technology now available at industry-first 64 percent efficiency |date=4 December 2017 |publisher= GE Power}}

In March 2018, GE Power achieved a 63.08% gross efficiency for its 7HA turbine.{{cite press release |url= https://www.ge.com/news/press-releases/ges-ha-gas-turbine-delivers-second-world-record-efficiency/ |title= GE's HA Gas Turbine Delivers Second World Record for Efficiency |publisher= GE Power |date= March 27, 2018}}

Aeroderivative gas turbines can also be used in combined cycles, leading to a higher efficiency, but it will not be as high as a specifically designed industrial gas turbine. They can also be run in a cogeneration configuration: the exhaust is used for space or water heating, or drives an absorption chiller for cooling the inlet air and increase the power output, technology known as turbine inlet air cooling.

Another significant advantage is their ability to be turned on and off within minutes, supplying power during peak, or unscheduled, demand. Since single cycle (gas turbine only) power plants are less efficient than combined cycle plants, they are usually used as peaking power plants, which operate anywhere from several hours per day to a few dozen hours per year—depending on the electricity demand and the generating capacity of the region. In areas with a shortage of base-load and load following power plant capacity or with low fuel costs, a gas turbine powerplant may regularly operate most hours of the day. A large single-cycle gas turbine typically produces 100 to 400 megawatts of electric power and has 35–40% thermodynamic efficiency.{{cite web |first1=Phil |last1=Ratliff |first2=Paul |last2=Garbett |first3=Willibald |last3=Fischer |title=The New Siemens Gas Turbine SGT5-8000H for More Customer Benefit |work=VGB PowerTech |publisher=Siemens Power Generation |date=September 2007 |url=http://www.energy.siemens.com/us/pool/hq/power-generation/gas-turbines/downloads/SGT5-8000H_benefits.pdf |access-date=17 July 2010 |archive-date=13 August 2011 |archive-url=https://web.archive.org/web/20110813030259/http://www.energy.siemens.com/us/pool/hq/power-generation/gas-turbines/downloads/SGT5-8000H_benefits.pdf |url-status=dead }}

File:Forssan varavoimala.JPG's gas turbine power plant in Forssa, Finland]]

In a simple cycle gas-turbine, also known as open-cycle gas-turbine (OCGT) generators, hot gas drives a gas turbine to generate electricity. This type of plant is relatively cheap to build and can start very quickly, but due to its lower efficiency is at most only run for a few hours a day as a peaking power plant.{{Cite web|url=https://energyeducation.ca/encyclopedia/Simple_cycle_gas_plant|title=Simple cycle gas plant - Energy Education|website=energyeducation.ca|access-date=2019-06-28}}

{{Main|Combined cycle power plant}}

CCGT power plants consist of simple cycle gas-turbines which use the Brayton cycle, followed by a heat recovery steam generator and a steam turbine which use the Rankine cycle. The most common configuration is two gas-turbines supporting one steam turbine.{{Cite web|url=https://www.eia.gov/todayinenergy/detail.php?id=38312|title=Power blocks in natural gas-fired combined-cycle plants are getting bigger - Today in Energy - U.S. Energy Information Administration (EIA)|website=www.eia.gov|access-date=2019-06-28}} They are slightly more expensive than simple cycle plants but can achieve efficiencies up to 55% and dispatch times of around half an hour.{{Cite web|url=https://energyeducation.ca/encyclopedia/Combined_cycle_gas_plant|title=Combined cycle gas plant - Energy Education|website=energyeducation.ca|access-date=2019-06-28}}

Gas-steam plants use gas to fire boilers which produce steam to turn steam turbines. Many of these types of plants were constructed through the 20th century as a direct alternative to coal plants. They lack the quick-start capabilities of simple cycle gas turbine plants, and are much less efficient than combined cycle plants. Owing to their age and deficiencies, they represent the vast majority of gas retirements in the United States, however, they still represent an option for extending the life of coal powered plants while reducing emissions by converting to gas burners.{{cite web |url=https://insight.factset.com/gas-power-plant-retirement-outlook |title=Gas Power Plant Retirement Outlook |last=Bradford |first=Andrew |date=28 October 2020 |website=FactSet |access-date=3 March 2025}}{{cite web |url=https://www.power-eng.com/environmental-emissions/oklahoma-gas-and-electric-eyes-coal-to-gas-switches-at-muskogee/ |title=Oklahoma Gas and Electric eyes coal-to-gas switches at Muskogee |last=Cassell |first=Barry |date=11 June 2014 |website=power-eng |access-date=3 March 2025}}{{cite web |url=https://www.cpsenergy.com/content/dam/corporate/en/Documents/RAC/2_Spruce2%20Gas%20Conversion%2001202022%20final%20.pdf |title=Spruce 2 Gas Conversion |last=Ethridge |first=Benjamin |date=20 January 2022 |access-date=3 March 2025}}

{{See also|Reciprocating engine}}

Reciprocating internal combustion engines tend to be under 20 MW, thus much smaller than other types of natural gas-fired electricity generator, and are typically used for emergency power or to balance variable renewable energy such as wind and solar.{{Cite web|url=https://www.eia.gov/todayinenergy/detail.php?id=37972|title=Natural gas-fired reciprocating engines are being deployed more to balance renewables - Today in Energy - U.S. Energy Information Administration (EIA)|website=www.eia.gov|access-date=2019-06-28}}

Relatively efficient gas-fired power stations – such as those based on combined cycle gas turbines – emit about {{convert|450|g|oz|0}} of {{CO2}} per kilowatt-hour of electricity generated.{{cite news |title=How sustainable is wind power? |date=2021-12-27 |first=Gero |last=Rueter |work=Deutsche Welle |url=https://m.dw.com/en/how-sustainable-is-wind-power/a-60268971 |access-date=2021-12-28 |quote=An onshore wind turbine that is newly built today produces around nine grams of CO2 for every kilowatt hour (kWh) it generates ... a new offshore plant in the sea emits seven grams of CO2 per kWh ... solar power plants emit 33 grams CO2 for every kWh generated ... natural gas produces 442 grams CO2 per kWh, power from hard coal 864 grams, and power from lignite, or brown coal, 1034 grams ... nuclear energy accounts for about 117 grams of CO2 per kWh, considering the emissions caused by uranium mining and the construction and operation of nuclear reactors. }}{{Cite journal |last1=Rosselot |first1=Kirsten S. |last2=Allen |first2=David T. |last3=Ku |first3=Anthony Y. |date=2021-07-05 |title=Comparing Greenhouse Gas Impacts from Domestic Coal and Imported Natural Gas Electricity Generation in China |url=https://pubs.acs.org/doi/10.1021/acssuschemeng.1c01517 |journal=ACS Sustainable Chemistry & Engineering |language=en |volume=9 |issue=26 |pages=8759–8769 |doi=10.1021/acssuschemeng.1c01517 |s2cid=237875562 |issn=2168-0485|doi-access=free }} This is about half that of coal-fired power stations but much more than nuclear power plants and renewable energy. However, the more flexible simple-cycle turbines have a significantly higher emissions intensity, frequently as high as {{convert|670|g|oz|0}} of CO₂ per kWh,{{Cite web |last=McConnell |first=Dylan |date=2017-02-24 |title=Our power grid is crying out for capacity, but should we open the gas valves? |url=https://theconversation.com/our-power-grid-is-crying-out-for-capacity-but-should-we-open-the-gas-valves-72355 |access-date=2024-10-25 |website=The Conversation |language=en-AU}} and some older gas turbines can have emissions intensities comparable with even the most emissions intensive coal power stations.{{Cite web |last=Gordon |first=Josh |date=2020-11-03 |title= Adam Bandt says gas is just as dirty as coal. Is he correct? |url=https://www.abc.net.au/news/2020-11-03/fact-check-is-gas-just-as-dirty-as-coal-adam-bandt/12838066 |access-date=2024-10-25 |website=RMIT ABC Fact Check |language=en-AU}}

However, full Life-cycle emissions of gas-fired power stations is increased by methane emissions from gas leaks associated with gas production and distribution pipelines as well as from significant venting of waste CO₂ after amine gas treating if carbon capture and storage is employed.https://www.nrel.gov/docs/fy00osti/27715.pdf {{Bare URL PDF|date=May 2025}}

Very few power plants have carbon capture and storage.{{Cite web |last=Chemnick |first=Jean |date=2022-05-09 |title=Why EPA might make new gas plants catch carbon |url=https://www.eenews.net/articles/why-epa-might-make-new-gas-plants-catch-carbon/ |access-date=2022-05-09 |website=E&E News |language=en-US}}

Gas-fired power plants can be modified to run on hydrogen,{{cite news |title=The plan to convert the North to run on hydrogen |url=https://utilityweek.co.uk/plan-convert-north-run-hydrogen/ |work=Utility Week |date=30 November 2018}} and according to General Electric a more economically viable option than CCS would be to use more and more hydrogen in the gas turbine fuel.{{Cite web|url=https://www.utilitydive.com/news/ge-hydrogen-trumps-ccs-in-preserving-gas-turbines-in-a-carbon-free-grid/556585/|title=GE: Hydrogen trumps carbon capture and sequestration (CCS) in preserving gas turbines in a carbon-free grid|website=Utility Dive|language=en-US|access-date=2019-06-28}} Hydrogen can at first be created from natural gas through steam reforming, or by heating to precipitate carbon, as a step towards a hydrogen economy, thus eventually reducing carbon emissions.{{cite web |title=H-vision: blue hydrogen for a green future |date=11 February 2019 |url=https://www.gasworld.com/blue-hydrogen-for-a-green-future/2016596.article |publisher=Gas World |access-date=9 May 2019}} However others think low-carbon hydrogen (such as natural hydrogen) should be used for things which are harder to decarbonize, such as making fertilizer, so there may not be enough for electricity generation.{{Cite web |title=Hydrogen could be used for nearly everything. It probably shouldn’t be. |url=https://www.technologyreview.com/2024/04/25/1091757/hydrogen-uses-ranked/ |access-date=2024-10-05 |website=MIT Technology Review |language=en}}

Sometimes a new battery storage power station together with solar power or wind power is cheaper in the long-term than building a new gas plant, as the gas plant risks becoming a stranded asset.{{Cite web|url=https://solarmagazine.com/natural-gas-power-stranded-asset-risk-reaches-a-tipping-point/|title=Natural Gas Power Stranded Asset Risk Reaches a Tipping Point|last=Andrew Burger|date=2019-10-07|website=Solar Magazine|language=en-US|access-date=2019-10-20}}

{{As of|2019}} a few gas-fired power plants are being retired because they are unable to stop and start quickly enough.{{Cite web|url=https://arstechnica.com/information-technology/2019/06/in-california-a-young-natural-gas-plant-closes-down-as-renewables-get-cheaper/|title=A 10-year-old natural gas plant in California gets the coal plant treatment|last=Geuss|first=Megan|date=2019-06-26|website=Ars Technica|language=en-us|access-date=2019-06-28}} Despite the falling cost of variable renewable energy most existing gas-fired power plants remain profitable, especially in countries without a carbon price, due to their dispatchable generation and because shale gas and liquefied natural gas prices have fallen since they were built.{{Cite web|url=https://www.livemint.com/market/mark-to-market/torrent-power-shares-make-a-powerful-leap-after-gujarat-arrangement-1561709553829.html|title=Torrent Power shares make a powerful leap after Gujarat arrangement|last=Ram|first=R. Sree|date=2019-06-28|language=en|access-date=2019-06-28}} Even in places with a carbon price, such as the EU, existing gas-fired power stations remain economically viable, partly due to increasing restrictions on coal-fired power because of its pollution.{{Cite web|url=https://www.worldoil.com/news/2019/6/11/natural-gas-price-plunge-signals-greener-start-for-2019-in-us-and-eu|title=Natural gas price plunge signals greener start for 2019 in U.S. and EU|website=www.worldoil.com|access-date=2019-06-28}}

Even when replacing coal power, the decision to build a new plant may be controversial.{{Cite news|url=https://www.bbc.com/news/business-49960817|title=UK overrules block on Drax power station plans|last=Harrabin|first=Roger|date=2019-10-07|access-date=2019-10-20|language=en-GB}}

• List of natural gas power stations

• [https://globalenergymonitor.org/projects/global-gas-plant-tracker/ Global gas plant tracker] by Global Energy Monitor

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Category:Natural gas-fired power stations

Category:Greenhouse gas emissions