Coal-fired power station
[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.
Coal-fired power stations are the largest single contributor to climate change,[8] releasing approximately 12 billion tonnes of carbon dioxide annually,[2] about one-fifth of global greenhouse gas emissions.
[10] While the total number of operational coal plants began declining in 2020,[11][12] due to retirements in Europe[13] and the Americas,[14] construction continues in Asia, primarily in China.
[15] The profitability of some plants is maintained by externalities, as the health and environmental costs of coal production and use are not fully reflected in electricity prices.
Steam turbines allowed much larger plants to be built in the early 20th century and alternating current was used to serve wider areas.
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.
The heat from the burning pulverized coal converts boiler water to steam, which is then used to spin turbines that turn generators.
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.
[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.
[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.
[32] Integrated gasification combined cycle (IGCC) is a coal-based power generation technology that uses a high-pressure gasifier to convert coal (or other carbon-based fuels) into pressurized synthesis gas (syngas).
[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.
[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.
[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.
[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.
[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, sulfur 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.
[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.
[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.
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.
[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.
[72] As renewable energy technologies become cost-competitive, the economic viability of coal projects diminishes, making past fossil fuel investments less attractive.
Strengthening the policies, potentially by banning public financing of coal projects entirely, would enhance their climate efforts and credibility.
[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.
[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.
