A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide there are about 2,500 coal-fired power stations, [1] on average capable of generating a gigawatt each. [2] [a] They generate about a third of the world's electricity, [3] but cause many illnesses and the most early deaths per unit of energy produced, [4] mainly from air pollution. [5] [6] World installed capacity doubled from 2000 to 2023 and increased 2% in 2023. [7]
A coal-fired power station is a type of fossil fuel power station. The coal is usually pulverized and then burned in a pulverized coal-fired boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines that turn generators. Thus chemical energy stored in coal is converted successively into thermal energy, mechanical energy and, finally, electrical energy.
Coal-fired power stations emit about 12 billion tonnes of carbon dioxide each year, [2] about one fifth of world greenhouse gas emissions, [8] so are the single largest cause of climate change. [9] More than half of all the coal-fired electricity in the world is generated in China. [10] In 2020 the total number of plants started falling [11] [12] as they are being retired in Europe [13] and America [14] although still being built in Asia, almost all in China. [15] Some remain profitable because costs to other people due to the health and environmental impact of the coal industry are not priced into the cost of generation, [16] [17] but there is the risk newer plants may become stranded assets. [18] The UN Secretary General has said that OECD countries should stop generating electricity from coal by 2030, and the rest of the world by 2040. [19]
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.
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 10,000 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 41,000 tonnes (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 14,000 cubic metres (90,000 bbl). The heavier no. 5 "bunker" and no. 6 fuels are typically steam-heated before pumping in cold climates.
As a type of thermal power station, a coal-fired power station converts chemical energy stored in coal successively into thermal energy, mechanical energy and, finally, electrical energy. The coal is usually pulverized and then burned in a pulverized coal-fired boiler. The heat from the burning pulverized coal converts boiler water to steam, which is then used to spin turbines that turn generators. Compared to a thermal power station burning other fuel types, coal specific fuel processing and ash disposal is required.
For units over about 200 MW capacity, redundancy of key components is provided by installing duplicates of the forced and induced draft fans, air preheaters, and fly ash collectors. On some units of about 60 MW, two boilers per unit may instead be provided. The hundred largest coal power stations range in size from 3,000 MW to 6,700 MW.
Coal is prepared for use by crushing the rough coal to pieces less than 5 cm (2 in) 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 tonnes 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.
Plants designed for lignite (brown coal) are used in locations as varied as Germany, Victoria, Australia, and North Dakota. Lignite is a much younger form of coal than black coal. It has a lower energy density than black coal and requires a much larger furnace for equivalent heat output. Such coals may contain up to 70% water and ash, yielding lower furnace temperatures and requiring larger induced-draft fans. The firing systems also differ from black coal and typically draw hot gas from the furnace-exit level and mix it with the incoming coal in fan-type mills that inject the pulverized coal and hot gas mixture into the boiler.
The ash is often stored in ash ponds. Although the use of ash ponds in combination with air pollution controls (such as wet scrubbers) decreases the amount of airborne pollutants, the structures pose serious health risks for the surrounding environment. [20] Power utility companies have often built the ponds without liners, especially in the United States, and therefore chemicals in the ash can leach into groundwater and surface waters. [21]
Since the 1990s, power utilities in the U.S. have designed many of their new plants with dry ash handling systems. The dry ash is disposed in landfills, which typically include liners and groundwater monitoring systems. [22] Dry ash may also be recycled into products such as concrete, structural fills for road construction and grout. [23]
Fly ash is captured and removed from the flue gas by electrostatic precipitators or fabric bag filters (or sometimes both) located at the outlet of the furnace and before the induced draft fan. The fly ash is periodically removed from the collection hoppers below the precipitators or bag filters. Generally, the fly ash is pneumatically transported to storage silos and stored on site in ash ponds, or transported by trucks or railroad cars to landfills.
At the bottom of the furnace, there is a hopper for collection of bottom ash. This hopper is kept filled with water to quench the ash and clinkers falling down from the furnace. Arrangements are included to crush the clinkers and convey the crushed clinkers and bottom ash to on-site ash ponds, or off-site to landfills. Ash extractors are used to discharge ash from municipal solid waste–fired boilers.
A well-designed energy policy, energy law and electricity market are critical for flexibility. [24] 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; [25] however, some flexibility improvements may be more expensive than renewable energy with batteries. [26]
As of 2020 [update] two-thirds of coal burned is to generate electricity. [12] In 2020 coal was the largest source of electricity at 34%. [27] Over half coal generation in 2020 was in China. [27] About 60% of electricity in China, India and Indonesia is from coal. [3]
In 2020 worldwide 2,059 GW of coal power was operational, 50 GW was commissioned, and 25 GW started construction (most of these three in China); and 38 GW retired (mostly USA and EU). [28]
In 2023, global coal power capacity increased to 2,130 GW, driven by China adding 47.4 GW. [29] : 7–64
At COP26 2021, countries have joined the Global Coal to Clean Power pledge. However, intricate challenges remain, particularly in developing countries such as Indonesia and Vietnam. [30]
There are 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). [31] Subcritical is the least efficient type, however recent innovations have allowed retrofits to older subcritical plants to meet or even exceed efficiency of supercritical plants. [32]
Integrated gasification combined cycle (IGCC) is a coal power generation technology that uses a high pressure gasifier to turn coal (or other carbon based fuels) into pressurized gas—synthesis gas (syngas). Converting the coal to gas enables the use of a combined cycle generator, typically achieving high efficiency. The IGCC process can also enable removal of some pollutants from the syngas prior to the power generation cycle. However, the technology is costly compared with conventional coal-fired power stations.
As coal is mainly carbon, coal-fired power stations have a high carbon intensity. On average, coal power stations emit far more greenhouse gas per unit electricity generated compared with other energy sources (see also life-cycle greenhouse-gas emissions of energy sources). In 2018 coal burnt to generate electricity emitted over 10 Gt CO2 [33] of the 34 Gt total from fuel combustion [34] (the overall total greenhouse gas emissions for 2018 was 55 Gt CO2e [35] ).
From 2015 to 2020, although coal generation hardly fell in absolute terms, some of its market share was taken by wind and solar. [27] In 2020 only China increased coal power generation, and globally it fell by 4%. [27] However, in 2021, China declared that it limited coal generation until 2025 and subsequently phase it out over time. [39] The UN Secretary General has said that OECD countries should stop generating electricity from coal by 2030 and the rest of the world by 2040, otherwise limiting global warming to 1.5 °C, a target of the Paris Agreement, would be extremely difficult. [19] A 2024 analysis by The Economist concluded that financing phase-out would be cheaper than carbon offsets. [2] However phasing out in Asia can be a financial challenge as plants there are relatively young: [3] in China the co-benefits of closing a plant vary greatly depending on its location. [40] Vietnam is among the few coal-dependent fast developing countries that fully pledged to phase out unbated coal power by the 2040s or as soon as possible thereafter. [41]
Ammonia has a high hydrogen density and is easy to handle. It can be used as storing carbon-free fuel in gas turbine power generation and help significantly reduce CO₂ emissions as a fuel. [42]
In Japan, the first major four-year test project was started in June 2021 to develop technology to enable co-firing a significant amount of ammonia at a large-scale commercial coal-fired plant. [43] [44] However low-carbon hydrogen and ammonia is in demand for sustainable shipping, which unlike electricity generation, has few other clean options. [45]
Some power stations are being converted to burn gas, biomass or waste, [46] and conversion to thermal storage will be trialled in 2023. [47]
Retrofitting some existing coal-fired power stations with carbon capture and storage was being considered in China in 2020, [48] but this is very expensive, [12] reduces the energy output and for some plants is not technically feasible. [49]
Coal burning power plants kill many thousands of people every year with their emissions of particulates, microscopic air pollutants that enter human lungs and other human organs and induce a variety of adverse medical conditions, including asthma, heart disease, low birth weight and cancers. In the U.S. alone, such particulates, known as PM2.5 (particulates with a diameter of 2.5 μm or less), caused at least 460,000 excess deaths over two decades. [50]
In some countries pollution is somewhat controlled by best available techniques, for example those in the EU [51] through its Industrial Emissions Directive. In the United States, coal-fired plants are governed at the national level by several air pollution regulations, including the Mercury and Air Toxics Standards (MATS) regulation, [52] by effluent guidelines for water pollution, [53] and by solid waste regulations under the Resource Conservation and Recovery Act (RCRA). [54]
Coal-fired power stations continue to pollute in lightly regulated countries; such as the Western Balkans, [55] India, Russia and South Africa; [56] causing over a hundred thousand early deaths each year. [5] [57] [58]
Damage to health 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. [56] Early deaths due to air pollution have been estimated at 200 per GW-year, however they may be higher around power plants where scrubbers are not used or lower if they are far from cities. [59] Evidence indicates that exposure to sulfur, sulfates, or PM2.5 from coal emissions may be associated with higher relative morbidity or mortality risk than that to other PM2.5 constituents or PM2.5 from other sources per unit concentration. [60]
Pollutants such as heavy metals leaching into ground water from unlined coal ash storage ponds or landfills pollute water, possibly for decades or centuries. [61] Pollutant discharges from ash ponds to rivers (or other surface water bodies) typically include arsenic, lead, mercury, selenium, chromium, and cadmium. [53]
Mercury emissions from coal-fired power plants can fall back onto the land and water in rain, and then be converted into methylmercury by bacteria. [62] Through biomagnification, this mercury can then reach dangerously high levels in fish. [63] More than half of atmospheric mercury comes from coal-fired power plants. [64]
Coal-fired power plants also emit sulfur dioxide and nitrogen. [65] These emissions lead to acid rain, which can restructure food webs and lead to the collapse of fish and invertebrate populations. [65] [66]
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. [67]
Coal power plants tend to serve as base load technology, as they have high availability factors, and are relatively difficult and expensive to ramp up and down. As such, they perform poorly in real-time energy markets, where they are unable to respond to changes in the locational marginal price. In the United States, this has been especially true in light of the advent of cheap natural gas, which can serve as a fuel in dispatchable power plants that substitute the role of baseload on the grid. [68]
In 2020 the coal industry was subsidized $US18 billion. [3]
Coal financing is the financial support provided for coal-related projects, encompassing coal mining and coal-fired power stations. [69] Its role in shaping the global energy landscape and its environmental and climate impacts have made it a subject of concern. The misalignment of coal financing with international climate objectives, particularly the Paris Agreement, has garnered attention. [70]
The Paris Agreement aims to restrict global warming to well below 2 degrees Celsius and ideally limit it to 1.5 degrees Celsius. Achieving these goals necessitates a substantial reduction in coal-related activities. [71]
Studies, including finance-based accounting of coal emissions, have revealed a misalignment of coal financing with climate objectives. [70] Major nations, such as China, Japan, and the U.S., have extended financial support to overseas coal power infrastructure. [69] [72] The largest backers are Chinese banks under the Belt and Road Initiative (BRI). [73] [69] This support has led to significant long-term climate and financial risks and harms the objectives of reducing CO2 emissions set by the Paris Agreement, of which China, the United States and Japan are signatories. A substantial portion of the associated CO2 emissions is anticipated to occur after 2019. [70]
Coal financing poses challenges to the global decarbonization of the power generation sector. [72] As renewable energy technologies become cost-competitive, the economic viability of coal projects diminishes, making past fossil fuel investments less attractive. [74] To address these concerns and align with climate goals, there is a growing call for stricter policies regarding overseas coal financing. [69] [70] Countries, including Japan and the U.S., have faced criticism for permitting the financing of certain coal projects. Strengthening the policies, potentially by banning public financing of coal projects entirely, would enhance their climate efforts and credibility. In addition, Enhanced transparency in disclosing financing details is crucial for evaluating their environmental impacts. [70]
In India capacity factors are below 60%. [75] In 2020 coal-fired power stations in the United States had an overall capacity factor of 40%; that is, they operated at a little less than half of their cumulative nameplate capacity. [76]
If global warming is limited to well below 2 °C as specified in the Paris Agreement, coal plant stranded assets of over US$500 billion are forecast by 2050, mostly in China. [77] In 2020 think tank Carbon Tracker estimated that 39% of coal-fired plants were already more expensive than new renewables and storage and that 73% would be by 2025. [78] As of 2020 [update] about half of China's coal power companies are losing money and old and small power plants "have no hope of making profits". [79] As of 2021 [update] India is keeping potential stranded assets operating by subsidizing them. [80] [81] [82]
In May 2021, the G7 committed to end support for coal-fired power stations within the year. [83] The G7's commitment to end coal support is significant as their coal capacity decreased from 23% (443 GW) in 2015 to 15% (310 GW) in 2023, reflecting a shift towards greener policies. This contrasts with China and India, where coal remains central to energy policy. [29] : 11
As of 2023, the Group of Twenty (G20) holds 92% of the world's operating coal capacity (1,968 GW) and 88% of pre-construction capacity (336 GW). [29] : 11
The energy policy of China regarding coal and coal in China are the most important factors regarding the future of coal-fired power stations, because the country has so many. [84] 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. [85]
In democracies coal power investment follows an environmental Kuznets curve. [86] The energy policy of India about coal is an issue in the politics of India. [87] [88]
In the 21st century people have often protested against opencast mining, for example at Hambach Forest, Akbelen Forest and Ffos-y-fran; [89] [90] and at sites of proposed new plants, such as in Kenya [91] and China. [92]
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is a type of fossil fuel, formed when dead plant matter decays into peat which is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits of coal originate in former wetlands called coal forests that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times.
Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery to end users or its storage, using for example, the pumped-storage method.
A fossil fuel power station is a thermal power station which burns a fossil fuel, such as coal, oil, or natural gas, to produce electricity. Fossil fuel power stations have machinery to convert the heat energy of combustion into mechanical energy, which then operates an electrical generator. The prime mover may be a steam turbine, a gas turbine or, in small plants, a reciprocating gas engine. All plants use the energy extracted from the expansion of a hot gas, either steam or combustion gases. Although different energy conversion methods exist, all thermal power station conversion methods have their efficiency limited by the Carnot efficiency and therefore produce waste heat.
Coal pollution mitigation is a series of systems and technologies that seek to mitigate health and environmental impact of burning coal for energy. Burning coal releases harmful substances that contribute to air pollution, acid rain, and greenhouse gas emissions. Mitigation includes precombustion approaches, such as cleaning coal, and post combustion approaches, include flue-gas desulfurization, selective catalytic reduction, electrostatic precipitators, and fly ash reduction. These measures aim to reduce coal's impact on human health and the environment.
The energy policy of India is to increase the locally produced energy in India and reduce energy poverty, with more focus on developing alternative sources of energy, particularly nuclear, solar and wind energy. Net energy import dependency was 40.9% in 2021-22. The primary energy consumption in India grew by 13.3% in FY2022-23 and is the third biggest with 6% global share after China and USA. The total primary energy consumption from coal, crude oil, natural gas, nuclear energy, hydroelectricity and renewable power is 809.2 Mtoe in the calendar year 2018. In 2018, India's net imports are nearly 205.3 million tons of crude oil and its products, 26.3 Mtoe of LNG and 141.7 Mtoe coal totaling to 373.3 Mtoe of primary energy which is equal to 46.13% of total primary energy consumption. India is largely dependent on fossil fuel imports to meet its energy demands – by 2030, India's dependence on energy imports is expected to exceed 53% of the country's total energy consumption.
China is both the world's largest energy consumer and the largest industrial country, and ensuring adequate energy supply to sustain economic growth has been a core concern of the Chinese Government since the founding of the People's Republic of China in 1949. Since the country's industrialization in the 1960s, China is currently the world's largest emitter of greenhouse gases, and coal in China is a major cause of global warming. China is also the world's largest renewable energy producer, and the largest producer of hydroelectricity, solar power and wind power in the world. The energy policy of China is connected to its industrial policy, where the goals of China's industrial production dictate its energy demand managements.
A gas-fired power plant, sometimes referred to as gas-fired power station, natural gas power plant, or methane gas power plant, is a thermal power station that burns natural gas to generate electricity. Gas-fired power plants generate almost a quarter of world electricity and are significant sources of greenhouse gas emissions. However, they can provide seasonal, dispatchable energy generation to compensate for variable renewable energy deficits, where hydropower or interconnectors are not available. In the early 2020s batteries became competitive with gas peaker plants.
Fossil fuel phase-out is the gradual reduction of the use and production of fossil fuels to zero, to reduce deaths and illness from air pollution, limit climate change, and strengthen energy independence. It is part of the ongoing renewable energy transition, but is being hindered by fossil fuel subsidies.
Coal generated about 19.5% of the electricity at utility-scale facilities in the United States in 2022, down from 38.6% in 2014 and 51% in 2001. In 2021, coal supplied 9.5 quadrillion British thermal units (2,800 TWh) of primary energy to electric power plants, which made up 90% of coal's contribution to U.S. energy supply. Utilities buy more than 90% of the coal consumed in the United States. There were over 200 coal powered units across the United States in 2024. Coal plants have been closing since the 2010s due to cheaper and cleaner natural gas and renewables. Due to measures such as scrubbers air pollution from the plants kills far fewer people nowadays, but deaths in 2020 from PM25 have been estimated at 1600. Environmentalists say that political action is needed to close them faster, to also reduce greenhouse gas emissions by the United States and better limit climate change.
Since 2013, the total primary energy consumption in India has been the third greatest in the world after China and the United States. Having the largest national population of over 1.4 billion people, though, its per capita energy consumption is still in the lower half of all nations'. India was a net energy importer to meet nearly 47% of its total primary energy in 2019.
Low-carbon electricity or low-carbon power is electricity produced with substantially lower greenhouse gas emissions over the entire lifecycle than power generation using fossil fuels. The energy transition to low-carbon power is one of the most important actions required to limit climate change.
China is the largest producer and consumer of coal and coal power in the world. The share of coal in the Chinese energy mix declined to 55% in 2021 according to the US Energy Information Agency.
China is the world's largest electricity producer, having overtaken the United States in 2011 after rapid growth since the early 1990s. In 2021, China produced 8.5 petawatt-hour (PWh) of electricity, approximately 30% of the world's electricity production.
Coal phase-out is an environmental policy intended to stop burning coal in coal-fired power plants and elsewhere, and is part of fossil fuel phase-out. Coal is the most carbon-intensive fossil fuel, therefore phasing it out is critical to limiting climate change as laid out in the Paris Agreement. The International Energy Agency (IEA) estimates that coal is responsible for over 30% of the global average temperature increase above pre-industrial levels. Some countries in the Powering Past Coal Alliance have already stopped.
Energy consumption per person in Turkey is similar to the world average, and over 85 per cent is from fossil fuels. From 1990 to 2017 annual primary energy supply tripled, but then remained constant to 2019. In 2019, Turkey's primary energy supply included around 30 per cent oil, 30 per cent coal, and 25 per cent gas. These fossil fuels contribute to Turkey's air pollution and its above average greenhouse gas emissions. Turkey mines its own lignite but imports three-quarters of its energy, including half the coal and almost all the oil and gas it requires, and its energy policy prioritises reducing imports.
Coal, cars and lorries vent more than a third of Turkey's five hundred million tonnes of annual greenhouse gas emissions. They are mostly carbon dioxide and part of the cause of climate change in Turkey. A quarter of the emissions are from electricity generation.
The Afşin-Elbistan power stations are two coal-fired power stations in Turkey, in Afşin District in Kahramanmaraş Province. Both Afşin-Elbistan A, built in the 1980s, and the newer Afşin-Elbistan B burn lignite from the nearby Elbistan coalfield.
İsken Sugözü power station is a 1320 MW operational coal fired power station in Turkey.
Coal in Turkey generated a third of the nation's electricity in 2023. There are 55 active coal-fired power stations with a total capacity of 21 gigawatts (GW). In 2023 coal imports for electricity generation cost 3.7 billion USD.
2% annual increase in the global operating coal fleet, which currently stands at 2,130 GW […] Figure 16: Global coal power capacity continues steady growth despite Paris Agreement, with a 2% uptick in 2023
China generated 53% of the world's total coal-fired power in 2020, nine percentage points more that five years earlier
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