Coal-fired power station: Difference between revisions
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{{hatnote|This page is about the specifics of power stations which burn coal. To compare with power stations which burn fuels such as natural gas see [[fossil fuel power station]], and for information common to all power stations which convert heat into electricity see [[thermal power station]].}} |
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#REDIRECT [[Fossil fuel power station]] |
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{{short description|One or more generators which convert coal into electricity}} |
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[[File:NTPL Tuticorin NLCIL.jpg|thumb|Subcritical coal-fired power stations such as this one in [[Tuticorin]],[[India]] are the least efficient type]] |
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[[File:Coal fired power plant diagram.svg|thumb|Coal-fired power station diagram]] |
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A '''coal-fired power station''' or '''coal power plant''' is a [[thermal power station]] which burns [[coal]] to [[electricity generation|generate electricity]]. [[List of coal power stations|Coal-fired power stations]] generate over a third of the world's electricity but cause hundreds of thousands of early deaths each year, mainly from [[air pollution]].<ref name=NRDC/> |
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Coal-fired power stations emit over 10 [[gigatonne|Gt]] of [[carbon dioxide]] each year,<ref name="IEA Emissions"/> so are the single largest source of the [[greenhouse gas]]es which are causing [[global warming]].<ref name=NRDC/> They are being retired in Europe and America; but {{as of|2019|lc=y}} still being built in Asia, funded by China. |
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==Basic concepts: heat into mechanical energy into electrical energy== |
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{{see also|Thermal power station}} |
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[[File:Coal-fired plant animation.ogv|thumb|Coal-fired power station animation]] |
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A coal-fired power station is a type of [[fossil fuel power station]]. The coal is usually pulverized and then burned in a [[furnace]] with a [[boiler]]. The furnace heat converts boiler water to [[steam]], which is then used to spin [[turbine]]s which turn [[electrical generator|generators]]. Thus chemical energy stored in [[coal]] is converted successively into [[thermal energy]], [[mechanical energy]] and, finally, [[electrical energy]]. |
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===Flexibility=== |
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A well-designed [[energy policy]], [[energy law]] and [[electricity market]] are critical for flexibility.<ref>{{Cite web|url=https://webstore.iea.org/status-of-power-system-transformation-2018-summary-for-policy-makers|title=Status of Power System Transformation 2018: Summary for Policy Makers|website=IEA Webstore|access-date=2019-07-03}}</ref> Although technically the flexibility of some coal-fired power stations could be improved they are less able to provide [[dispatchable generation]] than most [[gas-fired power plant]]s. The most important flexibility is low minimum load,<ref>{{Cite web|url=https://www.vgb.org/en/flexibility_toolbox.html?dfid=90943|title=Flexibility Toolbox|website=www.vgb.org|access-date=2019-07-03}}</ref> however some flexibility improvements may be more expensive than [[renewable energy]] with [[Rechargeable battery|batteries]].<ref>{{Cite web|url=https://about.bnef.com/blog/battery-powers-latest-plunge-costs-threatens-coal-gas/|title=Battery Power's Latest Plunge in Costs Threatens Coal, Gas|date=2019-03-26|website=BloombergNEF|language=en-US|access-date=2019-07-03}}</ref> |
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==Share of generation and generating countries== |
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{{As of|2018}} coal was the largest source of electricity at 38%, the same share as 20 years previously:<ref>{{Cite web|url=https://www.bp.com/en/global/corporate/energy-economics/statistical-review-of-world-energy/electricity.html|title=Electricity {{!}} Energy economics {{!}} Home|website=BP global|language=en|access-date=2019-07-03}}</ref> the only countries generating over 350 TWh in 2018 being [[Electricity_sector_in_China#Coal_power|China]](4732), [[Coal_mining_in_India#Electricity_generation|India]](1176) and the [[Coal power in the United States|USA]](1246).<ref>{{Cite web|url=https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2019-full-report.pdf|title=BP Statistical Review of World Energy 2019|last=|first=|date=|website=|archive-url=|archive-date=|dead-url=|access-date=}}</ref> |
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===Construction and retirement=== |
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{{As of|2018}} coal power under construction was 236 GW, planned 339 GW, and 50 GW was commissioned and 31 GW retired.<ref>{{Cite web|url=https://endcoal.org/wp-content/uploads/2019/03/BoomAndBust_2019_r6.pdf|title=Boom and Bust 2019: TRACKING THE GLOBAL COAL PLANT PIPELINE|last=|first=|date=|website=|archive-url=|archive-date=|dead-url=|access-date=}}</ref> |
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==Carbon dioxide emissions causing global warming== |
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{{See also|Fossil_fuel_power_station#Carbon_dioxide}} |
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As coal is mainly [[carbon]] coal-fired power stations have a high [[carbon intensity]]. [[Life-cycle greenhouse-gas emissions of energy sources|Compared with other energy sources]] on average they emit far more [[greenhouse gas]] per unit electricity generated. In 2018 coal burnt to generate electricity emitted over 10 Gt {{CO2}}<ref name="IEA Emissions">{{Cite web|url=https://www.iea.org/geco/emissions/|title=Emissions|website=www.iea.org|access-date=2019-07-04}}</ref> of the 34 Gt total from fuel combustion.<ref>{{Cite web|url=https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2019-full-report.pdf|title=BP Statistical Review of World Energy 2019|last=|first=|date=|website=|archive-url=|archive-date=|dead-url=|access-date=}}</ref> |
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===Mitigation=== |
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====Phase out==== |
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{{See also|Fossil fuel phase-out|Coal#Transition_away_from_coal}} |
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The most cost effective way to limit global warming to 1.5°C, a target of the [[Paris Agreement]], includes EU and OECD countries closing all coal-fired power stations by 2030, China by 2040 and the rest of the world by 2050.<ref>{{Cite web|url=https://climateanalytics.org/briefings/coal-phase-out/|title=Coal Phase Out|website=climateanalytics.org|language=en|access-date=2019-07-04}}</ref> |
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====Conversion==== |
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Some power stations are being converted to burn gas, [[biomass]] or waste.<ref>{{Cite web|url=https://simecatlantis.com/2018/11/05/uskmouth-power-station-conversion-project-update-and-epp-contract-award/|title=Uskmouth Power Station Conversion Project Update and EPP Contract Award|date=2018-11-05|website=SIMEC Atlantis Energy|language=en-GB|access-date=2019-07-04}}</ref> |
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====Carbon capture==== |
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{{As of|2019}} retrofitting existing coal-fired power stations with [[carbon capture and storage]] is being trialled, for example in China, but this reduces the energy output and for some plants may not be technically or economically feasible:<ref>{{Cite web|url=https://ukccsrc.ac.uk/news-events/blog/post-combustion-capture-retrofit-evolving-current-infrastructure-cleaner-energy|title=Post-Combustion Capture Retrofit: Evolving Current Infrastructure for Cleaner Energy {{!}} UKCCS Research Centre|website=ukccsrc.ac.uk|access-date=2019-07-04}}</ref> the economics of retrofit in China are still being researched.<ref>{{Cite web|url=https://www.kth.se/en/itm/inst/energiteknik/forskning/ecs/projects/carbon-capture-storage-ccs-in-china-s-power-plants-1.882169|title=Carbon Capture Storage (CCS) in China’s power plants|website=KTH|language=en-UK|access-date=2019-07-04}}</ref> |
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==Local pollution== |
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{{Main|Environmental impact of the coal industry}} |
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[[File:Coal power plant wastestreams - EPA.png|thumb|Coal power plant wastestreams]] |
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In some countries pollution is controlled by [[best available techniques]], for example those in the [[EU]]<ref>{{Citation|title=Commission Implementing Decision (EU) 2017/1442 of 31 July 2017 establishing best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for large combustion plants (notified under document C(2017) 5225) (Text with EEA relevance. )|date=2017-08-17|url=http://data.europa.eu/eli/dec_impl/2017/1442/oj/eng|issue=32017D1442|language=en|access-date=2019-07-05}}</ref> through its [[Industrial Emissions Directive]]. However coal-fired power stations pollute countries such as the Western [[Balkans|Balkans,]]<ref>{{Cite web|url=https://bankwatch.org/publication/chronic-coal-pollution|title=Chronic coal pollution|website=Bankwatch|language=en-US|access-date=2019-07-05}}</ref> [[India]], [[Russia]] and [[South Africa]],<ref name=ETH>{{Cite web|url=https://ethz.ch/en/news-and-events/eth-news/news/2019/02/global-impact-coal-power.html|title=The global impact of coal power|website=ethz.ch|language=en|access-date=2019-07-05}}</ref> causing hundreds of thousands of early deaths each year.<ref name=NRDC/> |
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===Local Air Pollution=== |
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Damage to heath from [[particulates]], [[sulphur dioxide]] and [[nitrogen oxide]] occurs mainly in Asia and is often due to burning low quality coal, such as [[lignite]], in plants lacking modern [[flue gas]] treatment.<ref name=ETH/> |
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===Water Pollution=== |
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Pollutants such as [[heavy metals]] leaching into ground water from unlined [[coal ash]] storage pollute water, possibly for decades or centuries.<ref>{{Cite news|url=https://www.theguardian.com/environment/2019/mar/04/us-coal-plants-contaminating-groundwater-toxins-analysis|title=Most US coal plants are contaminating groundwater with toxins, analysis finds|last=Milman|first=Oliver|date=2019-03-04|work=The Guardian|access-date=2019-07-05|language=en-GB|issn=0261-3077}}</ref> |
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===Mitigation of local pollution=== |
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{{Main|Coal pollution mitigation}} |
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{{As of|2018}} local pollution in China, which has by far the most coal-fired power stations, is forecast to be reduced further in the 2020s and 2030s, especially if small and low efficiency plants are retired early.<ref>{{Cite journal|last=Tong|first=Dan|last2=Zhang|first2=Qiang|last3=Liu|first3=Fei|last4=Geng|first4=Guannan|last5=Zheng|first5=Yixuan|last6=Xue|first6=Tao|last7=Hong|first7=Chaopeng|last8=Wu|first8=Ruili|last9=Qin|first9=Yu|date=2018-11-06|title=Current Emissions and Future Mitigation Pathways of Coal-Fired Power Plants in China from 2010 to 2030|url=https://doi.org/10.1021/acs.est.8b02919|journal=Environmental Science & Technology|volume=52|issue=21|pages=12905–12914|doi=10.1021/acs.est.8b02919|issn=0013-936X}}</ref> |
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==Transport and delivery of coal== |
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[[File:Grand Junction Trip 92007 098.JPG|thumb|[[Carbon Power Plant|Castle Gate Plant]] near [[Helper, Utah]].]] |
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Coal is delivered by highway [[truck]], [[railroad|rail]], [[barge]], [[Collier (ship type)|collier]] ship or [[coal slurry pipeline]]. Generating stations are sometimes built next to a mine; especially one mining coal, such as [[lignite]], which is not valuable enough to transport long-distance; so may receive coal by [[conveyor belt]] or massive [[diesel-electric]]-drive [[haul truck|trucks]]. A large coal [[train]] called a "unit train" may be 2 km long, containing 130-140 cars with around 100 tonnes of coal in each one, for a total load of over 10000 tonnes. A large plant under full load requires at least one coal delivery this size every day. Plants may get as many as three to five trains a day, especially in "peak season" during the hottest summer or coldest winter months (depending on local climate) when power consumption is high. |
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Modern unloaders use rotary dump devices, which eliminate problems with coal freezing in bottom dump cars. The unloader includes a train positioner arm that pulls the entire train to position each car over a coal hopper. The dumper clamps an individual car against a platform that swivels the car upside down to dump the coal. Swiveling couplers enable the entire operation to occur while the cars are still coupled together. Unloading a unit train takes about three hours. |
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Shorter trains may use railcars with an "air-dump", which relies on air pressure from the engine plus a "hot shoe" on each car. This "hot shoe" when it comes into contact with a "hot rail" at the unloading trestle, shoots an electric charge through the air dump apparatus and causes the doors on the bottom of the car to open, dumping the coal through the opening in the trestle. Unloading one of these trains takes anywhere from an hour to an hour and a half. Older unloaders may still use manually operated bottom-dump rail cars and a "shaker" attached to dump the coal. |
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A collier (cargo ship carrying coal) may hold 40,000 long tons of coal and takes several days to unload. Some colliers carry their own conveying equipment to unload their own bunkers; others depend on equipment at the plant. For transporting coal in calmer waters, such as rivers and lakes, flat-bottomed [[barge]]s are often used. Barges are usually unpowered and must be moved by [[tugboat]]s or [[towboat]]s. |
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For start up or auxiliary purposes, the plant may use fuel oil as well. Fuel oil can be delivered to plants by [[Pipeline transport|pipeline]], [[Tanker (ship)|tanker]], [[tank car]] or truck. Oil is stored in vertical cylindrical steel tanks with capacities as high as {{convert|90000|oilbbl}}' worth. The [[viscosity|heavier]] no. 5 "bunker" and no. 6 fuels are typically steam-heated before pumping in cold climates. |
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==Components== |
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[[File:PowerStation3.svg|thumb|Components of a coal-fired power station]] |
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As well as the normal components of any [[thermal power station]] coal specific fuel processing and ash disposal is required. |
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===Fuel processing=== |
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Coal is prepared for use by crushing the rough coal to pieces less than 5 cm in size. The coal is then transported from the storage yard to in-plant storage silos by [[conveyor belt]]s at rates up to 4,000 tonnes per hour. |
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In plants that burn pulverized coal, silos feed coal to [[pulverizer]]s (coal mills) that take the larger 5 cm pieces, grind them to the consistency of [[talcum powder]], sort them, and mix them with primary combustion air which transports the coal to the boiler furnace and preheats the coal in order to drive off excess moisture content. A 500 MWe plant may have six such pulverizers, five of which can supply coal to the furnace at 250 tons per hour under full load. |
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In plants that do not burn pulverized coal, the larger 5 cm pieces may be directly fed into the silos which then feed either mechanical distributors that drop the coal on a traveling grate or the [[Cyclone furnace|cyclone]] burners, a specific kind of combustor that can efficiently burn larger pieces of fuel. |
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===Ash disposal=== |
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{{main|Bottom ash|Fly ash}} |
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The ash is often stored in [[ash pond]]s. |
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==Efficiency== |
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The 4 main types of coal-fired power station in increasing order of efficiency are: subcritical, [[Supercritical steam generator|supercritical]], ultra-supercritical and [[cogeneration]] (also called combined heat and power or CHP). Subcritical plants are incompatible with [[sustainable development]].<ref>{{Cite web|url=https://www.iea.org/tcep/power/coal/|title=Coal|website=www.iea.org|access-date=2019-07-05}}</ref> |
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==Economics== |
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===Subsidies=== |
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[[G20]] governments alone subsidize coal by at least US$63.9 billion per year, almost three-quarters of which is for coal-fired power.<ref name=NRDC>{{Cite web|url=https://www.odi.org/sites/odi.org.uk/files/resource-documents/12745.pdf|title=G20 coal subsidies|last=|first=|date=|website=|archive-url=|archive-date=|dead-url=|access-date=}}</ref> |
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===Finance=== |
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{{See also|Fossil fuel divestment}} |
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{{As of|2019}} the largest backers are Chinese banks under the [[Belt and Road Initiative]] (BRI).<ref>{{Cite web|url=https://www.ft.com/content/1efe4e16-9b61-11e9-b8ce-8b459ed04726|title=The week in energy: China’s coal-fired outreach|last=Crooks|first=Ed|date=2019-06-30|website=Financial Times|language=en-GB|access-date=2019-07-06}}</ref> |
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===Stranded assets=== |
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In 2018 the head of the [[International Monetary Fund]] said it would look into what risk coal plants becoming [[Stranded asset|stranded assets]] posed to the economies of [[Southeast Asia]].<ref>{{Cite web|url=https://energytransition.org/2018/11/coal-assets-stranded-in-southeast-asia/|title=Coal assets stranded in Southeast Asia|date=2018-11-30|website=Energy Transition|language=en-US|access-date=2019-07-06}}</ref> |
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==Politics== |
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[[File:Protest of Greenpeace with coal in front of the German Chancellery 03.jpg|thumb|[[Greenpeace]] protesting against coal at the [[German Chancellery]]]] |
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{{See also|Energy_policy_of_China#Coal}} |
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In [[democracies]] coal power investment follows an [[environmental Kuznets curve]].<ref>{{Cite journal|last=Urpelainen|first=Johannes|last2=Zucker|first2=Noah|last3=Clark|first3=Richard|date=2019-04-11|title=Political Institutions and Pollution: Evidence from Coal-Fired Power Generation|url=https://papers.ssrn.com/abstract=3370276|language=en|location=Rochester, NY}}</ref> The [[Energy_policy_of_India#Coal|energy policy of India regarding coal]] is forecast to result in half of the country's electricity still being generated by coal in 2030.<ref>{{Cite news|url=https://economictimes.indiatimes.com/industry/energy/power/coal-to-dominate-india-power-to-2030-despite-renewables-boost/articleshow/70040887.cms|title=Coal to dominate India power to 2030 despite renewables boost|date=2019-07-02|work=The Economic Times|access-date=2019-07-06}}</ref> |
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In China according to one analysis local officials overinvested in coal-fired power in the mid-2010s because central government guaranteed operating hours and set a high wholesale electricity price.<ref>{{Cite web|url=https://voxeu.org/article/china-overinvested-coal-power-here-s-why|title=China overinvested in coal power: Here’s why|last=Ren|first=Mengjia|last2=Branstetter|first2=Lee|date=2019-03-16|website=VoxEU.org|access-date=2019-07-06|last3=Kovak|first3=Brian|last4=Armanios|first4=Daniel|last5=Yuan|first5=Jiahai}}</ref> {{As of|2019}} BRI investment may be to keep skilled people employed<ref>{{Cite web|url=https://www.npr.org/2019/04/29/716347646/why-is-china-placing-a-global-bet-on-coal|title=Why Is China Placing A Global Bet On Coal?|website=NPR.org|language=en|access-date=2019-07-06}}</ref> and because banks and [[state owned enterprises]] need somewhere to place their capital and expertise.<ref>{{Cite web|url=https://sites.duke.edu/policy360/2019/06/03/ep-93-china-coal/|title=Ep. 93 China’s Investment in Coal Around the World – Policy 360 podcast|language=en-US|access-date=2019-07-06}}</ref> |
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===Protests=== |
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Protests have often been at mining sites<ref>{{Cite web|url=http://climatetracker.org/successful-protest-indias-coal-industry/|title=Successful Protests Against India's Coal Industry|last=Ch|first=Aruna|last2=rasekar|date=2017-09-26|website=Climate Tracker|language=en-US|access-date=2019-07-06}}</ref><ref>{{Cite web|url=https://www.cnn.com/2019/06/23/europe/germany-climate-protest-garzweiler-coal-mine-intl-scli-grm/index.html|title=Hundreds of climate protesters stage blockade in German coal mine|last=CNN|first=Matthew Robinson|website=CNN|access-date=2019-07-06}}</ref> and at sites of proposed new plants.<ref>{{Cite news|url=https://www.bbc.com/news/uk-48503020|title=Row over Kenya World Heritage site coal plant|last=Leithead|first=Alastair|date=2019-06-05|access-date=2019-07-06|language=en-GB}}</ref> |
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==History== |
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[[File:Edison Electric Light Station, Holborn Viaduct, London.jpg|thumb|[[Holborn Viaduct power station]] in [[London]], the world's first public steam-driven coal power station, opened in 1882]] |
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{{See also|Power_station#History}} |
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The first coal-fired power stations were built in the late 19th century and used [[reciprocating engine]]s to generate [[direct current]]. [[Steam turbine]]s allowed much larger plants to be built in the early 20th century and [[alternating current]] was used to serve wider areas. |
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==See also== |
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[[Global Energy Monitor]] |
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==External links== |
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https://energyeducation.ca/encyclopedia/Coal_fired_power_plant |
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https://www.tva.com/Energy/Our-Power-System/Coal/How-a-Coal-Plant-Works |
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https://www.youtube.com/watch?v=SeXG8K5_UvU how works another vid |
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https://www.worldcoal.org/coal/uses-coal/coal-electricity |
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https://www.carbonbrief.org/mapped-worlds-coal-power-plants |
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https://poweringpastcoal.org/ |
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https://endcoal.org |
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https://www.iea.org/tcep/power/coal/ |
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https://www.carbontracker-coal-economics-portal.com/ |
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==References== |
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{{Reflist}} |
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Revision as of 12:18, 6 July 2019
A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Coal-fired power stations generate over a third of the world's electricity but cause hundreds of thousands of early deaths each year, mainly from air pollution.[1]
Coal-fired power stations emit over 10 Gt of carbon dioxide each year,[2] so are the single largest source of the greenhouse gases which are causing global warming.[1] They are being retired in Europe and America; but as of 2019[update] still being built in Asia, funded by China.
Basic concepts: heat into mechanical energy into electrical energy
A coal-fired power station is a type of fossil fuel power station. The coal is usually pulverized and then burned in a furnace with a boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines which turn generators. Thus chemical energy stored in coal is converted successively into thermal energy, mechanical energy and, finally, electrical energy.
Flexibility
A well-designed energy policy, energy law and electricity market are critical for flexibility.[3] Although technically the flexibility of some coal-fired power stations could be improved they are less able to provide dispatchable generation than most gas-fired power plants. The most important flexibility is low minimum load,[4] however some flexibility improvements may be more expensive than renewable energy with batteries.[5]
Share of generation and generating countries
As of 2018[update] coal was the largest source of electricity at 38%, the same share as 20 years previously:[6] the only countries generating over 350 TWh in 2018 being China(4732), India(1176) and the USA(1246).[7]
Construction and retirement
As of 2018[update] coal power under construction was 236 GW, planned 339 GW, and 50 GW was commissioned and 31 GW retired.[8]
Carbon dioxide emissions causing global warming
As coal is mainly carbon coal-fired power stations have a high carbon intensity. Compared with other energy sources on average they emit far more greenhouse gas per unit electricity generated. In 2018 coal burnt to generate electricity emitted over 10 Gt CO2[2] of the 34 Gt total from fuel combustion.[9]
Mitigation
Phase out
The most cost effective way to limit global warming to 1.5°C, a target of the Paris Agreement, includes EU and OECD countries closing all coal-fired power stations by 2030, China by 2040 and the rest of the world by 2050.[10]
Conversion
Some power stations are being converted to burn gas, biomass or waste.[11]
Carbon capture
As of 2019[update] retrofitting existing coal-fired power stations with carbon capture and storage is being trialled, for example in China, but this reduces the energy output and for some plants may not be technically or economically feasible:[12] the economics of retrofit in China are still being researched.[13]
Local pollution
In some countries pollution is controlled by best available techniques, for example those in the EU[14] through its Industrial Emissions Directive. However coal-fired power stations pollute countries such as the Western Balkans,[15] India, Russia and South Africa,[16] causing hundreds of thousands of early deaths each year.[1]
Local Air Pollution
Damage to heath from particulates, sulphur dioxide and nitrogen oxide occurs mainly in Asia and is often due to burning low quality coal, such as lignite, in plants lacking modern flue gas treatment.[16]
Water Pollution
Pollutants such as heavy metals leaching into ground water from unlined coal ash storage pollute water, possibly for decades or centuries.[17]
Mitigation of local pollution
As of 2018[update] local pollution in China, which has by far the most coal-fired power stations, is forecast to be reduced further in the 2020s and 2030s, especially if small and low efficiency plants are retired early.[18]
Transport and delivery of coal
Coal is delivered by highway truck, rail, barge, collier ship or coal slurry pipeline. Generating stations are sometimes built next to a mine; especially one mining coal, such as lignite, which is not valuable enough to transport long-distance; so may receive coal by conveyor belt or massive diesel-electric-drive trucks. A large coal train called a "unit train" may be 2 km long, containing 130-140 cars with around 100 tonnes of coal in each one, for a total load of over 10000 tonnes. A large plant under full load requires at least one coal delivery this size every day. Plants may get as many as three to five trains a day, especially in "peak season" during the hottest summer or coldest winter months (depending on local climate) when power consumption is high.
Modern unloaders use rotary dump devices, which eliminate problems with coal freezing in bottom dump cars. The unloader includes a train positioner arm that pulls the entire train to position each car over a coal hopper. The dumper clamps an individual car against a platform that swivels the car upside down to dump the coal. Swiveling couplers enable the entire operation to occur while the cars are still coupled together. Unloading a unit train takes about three hours.
Shorter trains may use railcars with an "air-dump", which relies on air pressure from the engine plus a "hot shoe" on each car. This "hot shoe" when it comes into contact with a "hot rail" at the unloading trestle, shoots an electric charge through the air dump apparatus and causes the doors on the bottom of the car to open, dumping the coal through the opening in the trestle. Unloading one of these trains takes anywhere from an hour to an hour and a half. Older unloaders may still use manually operated bottom-dump rail cars and a "shaker" attached to dump the coal.
A collier (cargo ship carrying coal) may hold 40,000 long tons of coal and takes several days to unload. Some colliers carry their own conveying equipment to unload their own bunkers; others depend on equipment at the plant. For transporting coal in calmer waters, such as rivers and lakes, flat-bottomed barges are often used. Barges are usually unpowered and must be moved by tugboats or towboats.
For start up or auxiliary purposes, the plant may use fuel oil as well. Fuel oil can be delivered to plants by pipeline, tanker, tank car or truck. Oil is stored in vertical cylindrical steel tanks with capacities as high as 90,000 barrels (14,000 m3)' worth. The heavier no. 5 "bunker" and no. 6 fuels are typically steam-heated before pumping in cold climates.
Components
As well as the normal components of any thermal power station coal specific fuel processing and ash disposal is required.
Fuel processing
Coal is prepared for use by crushing the rough coal to pieces less than 5 cm in size. The coal is then transported from the storage yard to in-plant storage silos by conveyor belts at rates up to 4,000 tonnes per hour.
In plants that burn pulverized coal, silos feed coal to pulverizers (coal mills) that take the larger 5 cm pieces, grind them to the consistency of talcum powder, sort them, and mix them with primary combustion air which transports the coal to the boiler furnace and preheats the coal in order to drive off excess moisture content. A 500 MWe plant may have six such pulverizers, five of which can supply coal to the furnace at 250 tons per hour under full load.
In plants that do not burn pulverized coal, the larger 5 cm pieces may be directly fed into the silos which then feed either mechanical distributors that drop the coal on a traveling grate or the cyclone burners, a specific kind of combustor that can efficiently burn larger pieces of fuel.
Ash disposal
The ash is often stored in ash ponds.
Efficiency
The 4 main types of coal-fired power station in increasing order of efficiency are: subcritical, supercritical, ultra-supercritical and cogeneration (also called combined heat and power or CHP). Subcritical plants are incompatible with sustainable development.[19]
Economics
Subsidies
G20 governments alone subsidize coal by at least US$63.9 billion per year, almost three-quarters of which is for coal-fired power.[1]
Finance
As of 2019[update] the largest backers are Chinese banks under the Belt and Road Initiative (BRI).[20]
Stranded assets
In 2018 the head of the International Monetary Fund said it would look into what risk coal plants becoming stranded assets posed to the economies of Southeast Asia.[21]
Politics
In democracies coal power investment follows an environmental Kuznets curve.[22] The energy policy of India regarding coal is forecast to result in half of the country's electricity still being generated by coal in 2030.[23]
In China according to one analysis local officials overinvested in coal-fired power in the mid-2010s because central government guaranteed operating hours and set a high wholesale electricity price.[24] As of 2019[update] BRI investment may be to keep skilled people employed[25] and because banks and state owned enterprises need somewhere to place their capital and expertise.[26]
Protests
Protests have often been at mining sites[27][28] and at sites of proposed new plants.[29]
History
The first coal-fired power stations were built in the late 19th century and used reciprocating engines to generate direct current. Steam turbines allowed much larger plants to be built in the early 20th century and alternating current was used to serve wider areas.
See also
External links
https://energyeducation.ca/encyclopedia/Coal_fired_power_plant
https://www.tva.com/Energy/Our-Power-System/Coal/How-a-Coal-Plant-Works
https://www.youtube.com/watch?v=SeXG8K5_UvU how works another vid
https://www.worldcoal.org/coal/uses-coal/coal-electricity
https://www.carbonbrief.org/mapped-worlds-coal-power-plants
https://www.iea.org/tcep/power/coal/
https://www.carbontracker-coal-economics-portal.com/
References
- ^ a b c d "G20 coal subsidies" (PDF).
{{cite web}}: Cite has empty unknown parameter:|dead-url=(help) - ^ a b "Emissions". www.iea.org. Retrieved 2019-07-04.
- ^ "Status of Power System Transformation 2018: Summary for Policy Makers". IEA Webstore. Retrieved 2019-07-03.
- ^ "Flexibility Toolbox". www.vgb.org. Retrieved 2019-07-03.
- ^ "Battery Power's Latest Plunge in Costs Threatens Coal, Gas". BloombergNEF. 2019-03-26. Retrieved 2019-07-03.
- ^ "Electricity | Energy economics | Home". BP global. Retrieved 2019-07-03.
- ^ "BP Statistical Review of World Energy 2019" (PDF).
{{cite web}}: Cite has empty unknown parameter:|dead-url=(help) - ^ "Boom and Bust 2019: TRACKING THE GLOBAL COAL PLANT PIPELINE" (PDF).
{{cite web}}: Cite has empty unknown parameter:|dead-url=(help) - ^ "BP Statistical Review of World Energy 2019" (PDF).
{{cite web}}: Cite has empty unknown parameter:|dead-url=(help) - ^ "Coal Phase Out". climateanalytics.org. Retrieved 2019-07-04.
- ^ "Uskmouth Power Station Conversion Project Update and EPP Contract Award". SIMEC Atlantis Energy. 2018-11-05. Retrieved 2019-07-04.
- ^ "Post-Combustion Capture Retrofit: Evolving Current Infrastructure for Cleaner Energy | UKCCS Research Centre". ukccsrc.ac.uk. Retrieved 2019-07-04.
- ^ "Carbon Capture Storage (CCS) in China's power plants". KTH. Retrieved 2019-07-04.
- ^ Commission Implementing Decision (EU) 2017/1442 of 31 July 2017 establishing best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for large combustion plants (notified under document C(2017) 5225) (Text with EEA relevance. ), 2017-08-17, retrieved 2019-07-05
- ^ "Chronic coal pollution". Bankwatch. Retrieved 2019-07-05.
- ^ a b "The global impact of coal power". ethz.ch. Retrieved 2019-07-05.
- ^ Milman, Oliver (2019-03-04). "Most US coal plants are contaminating groundwater with toxins, analysis finds". The Guardian. ISSN 0261-3077. Retrieved 2019-07-05.
- ^ Tong, Dan; Zhang, Qiang; Liu, Fei; Geng, Guannan; Zheng, Yixuan; Xue, Tao; Hong, Chaopeng; Wu, Ruili; Qin, Yu (2018-11-06). "Current Emissions and Future Mitigation Pathways of Coal-Fired Power Plants in China from 2010 to 2030". Environmental Science & Technology. 52 (21): 12905–12914. doi:10.1021/acs.est.8b02919. ISSN 0013-936X.
- ^ "Coal". www.iea.org. Retrieved 2019-07-05.
- ^ Crooks, Ed (2019-06-30). "The week in energy: China's coal-fired outreach". Financial Times. Retrieved 2019-07-06.
- ^ "Coal assets stranded in Southeast Asia". Energy Transition. 2018-11-30. Retrieved 2019-07-06.
- ^ Urpelainen, Johannes; Zucker, Noah; Clark, Richard (2019-04-11). "Political Institutions and Pollution: Evidence from Coal-Fired Power Generation". Rochester, NY.
{{cite journal}}: Cite journal requires|journal=(help) - ^ "Coal to dominate India power to 2030 despite renewables boost". The Economic Times. 2019-07-02. Retrieved 2019-07-06.
- ^ Ren, Mengjia; Branstetter, Lee; Kovak, Brian; Armanios, Daniel; Yuan, Jiahai (2019-03-16). "China overinvested in coal power: Here's why". VoxEU.org. Retrieved 2019-07-06.
- ^ "Why Is China Placing A Global Bet On Coal?". NPR.org. Retrieved 2019-07-06.
- ^ "Ep. 93 China's Investment in Coal Around the World – Policy 360 podcast". Retrieved 2019-07-06.
- ^ Ch, Aruna; rasekar (2017-09-26). "Successful Protests Against India's Coal Industry". Climate Tracker. Retrieved 2019-07-06.
- ^ CNN, Matthew Robinson. "Hundreds of climate protesters stage blockade in German coal mine". CNN. Retrieved 2019-07-06.
{{cite web}}:|last=has generic name (help) - ^ Leithead, Alastair (2019-06-05). "Row over Kenya World Heritage site coal plant". Retrieved 2019-07-06.