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98-429: Drywall (also called plasterboard , dry lining , wallboard , sheet rock , gib board , gypsum board , buster board , turtles board , slap board , custard board , gypsum panel and gyprock) is a panel made of calcium sulfate dihydrate ( gypsum ), with or without additives, typically extruded between thick sheets of facer and backer paper , used in the construction of interior walls and ceilings. The plaster

196-468: A building material . Drying chambers typically use natural gas today. To dry 1,000 square feet (93 m) of wallboard, between 1,750,000 and 2,490,000 BTU (1.85–2.63 GJ) is required. Organic dispersants and plasticizers are used so that the slurry will flow during manufacture and to reduce the water and hence the drying time. Coal-fired power stations include devices called scrubbers to remove sulfur from their exhaust emissions. The sulfur

294-489: A coagulant in products such as tofu . For the FDA , it is permitted in cheese and related cheese products; cereal flours; bakery products; frozen desserts; artificial sweeteners for jelly & preserves; condiment vegetables; and condiment tomatoes and some candies. It is known in the E number series as E516 , and the UN's FAO knows it as a firming agent, a flour treatment agent,

392-484: A gigawatt each. They generate about a third of the world's electricity , but cause many illnesses and the most early deaths per unit of energy produced, mainly from air pollution . World installed capacity doubled from 2000 to 2023 and increased 2% in 2023. 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

490-417: 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

588-586: A better finish, the entire wall may be given a skim coat, a thin layer (about 1 mm or 1 ⁄ 32  in) of finishing compound, to minimize the visual differences between the paper and mudded areas after painting. Another similar skim coating process is called veneer plastering, although it is done slightly thicker (about 2 mm or 3 ⁄ 32  in). Veneering uses a slightly different specialized setting compound ("finish plaster") that contains gypsum and lime putty . This application uses blueboard, which has specially treated paper to accelerate

686-418: A fire, the structure behind a sheet of drywall will remain relatively cool as water is lost from the gypsum, thus preventing (or substantially retarding) damage to the framing (through combustion of wood members or loss of strength of steel at high temperatures) and consequent structural collapse. But at higher temperatures, calcium sulfate will release oxygen and act as an oxidizing agent . This property

784-413: A retarder, and various additives that may increase mildew and fire resistance, lower water absorption ( wax emulsion or silanes ), reduce creep (tartaric or boric acid). The board is then formed by sandwiching a core of the wet mixture between two sheets of heavy paper or fiberglass mats. When the core sets, it is dried in a large drying chamber, and the sandwich becomes rigid and strong enough for use as

882-405: A sequestrant, and a leavening agent. Calcium sulfate has a long history of use in dentistry. It has been used in bone regeneration as a graft material and graft binder (or extender) and as a barrier in guided bone tissue regeneration. It is a biocompatible material and is completely resorbed following implantation. It does not evoke a significant host response and creates a calcium-rich milieu in

980-528: A substantial reduction in coal-related activities. Studies, including finance-based accounting of coal emissions, have revealed a misalignment of coal financing with climate objectives. Major nations, such as China, Japan, and the U.S., have extended financial support to overseas coal power infrastructure. The largest backers are Chinese banks under the Belt and Road Initiative (BRI). This support has led to significant long-term climate and financial risks and harms

1078-481: 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

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1176-428: 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

1274-439: A week-long plaster application, an entire house can be drywalled in one or two days by two experienced drywallers , and drywall is easy enough to be installed by many amateur home carpenters. In large-scale commercial construction, the work of installing and finishing drywall is often split between drywall mechanics, or hangers , who install the wallboard, and tapers (also known as finishers, mud men , or float crew) who finish

1372-513: Is exothermic and is responsible for the ease with which gypsum can be cast into various shapes including sheets (for drywall ), sticks (for blackboard chalk), and molds (to immobilize broken bones, or for metal casting). Mixed with polymers, it has been used as a bone repair cement. Small amounts of calcined gypsum are added to earth to create strong structures directly from cast earth , an alternative to adobe (which loses its strength when wet). The conditions of dehydration can be changed to adjust

1470-492: Is 48 inches; however, 54-inch-wide panels are becoming more popular as 9-foot (2.7 m) ceiling heights become more common. Lengths up to 16 feet (4.9 m) are common; the most common is 8 feet (2.4 m). Common thicknesses are 1 ⁄ 2 and 5 ⁄ 8 inch (13 and 16 mm); thicknesses of 1 ⁄ 4 ,  3 ⁄ 8 ,  3 ⁄ 4 , and 1 inch (6, 10, 19, and 25 mm) are used in specific applications. In many parts of Canada, drywall

1568-413: 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

1666-408: Is a growing call for stricter policies regarding overseas coal financing. 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

1764-513: Is absorbed by powdered limestone in a process called flue-gas desulfurization (FGD), which produces several new substances. One is called "FGD gypsum". This is commonly used in drywall construction in the United States and elsewhere. In 2020, 8.4 billion square meters of drywall were sold around the world. The term plasterboard is used in Australia and New Zealand . In Australia, the product

1862-466: Is also a common component of fouling deposits in industrial heat exchangers, because its solubility decreases with increasing temperature (see the specific section on the retrograde solubility). The solubility of calcium sulfate decreases as temperature increases. This behaviour ("retrograde solubility") is uncommon: dissolution of most of the salts is endothermic and their solubility increases with temperature.The retrograde solubility of calcium sulfate

1960-564: Is also responsible for its precipitation in the hottest zone of heating systems and for its contribution to the formation of scale in boilers along with the precipitation of calcium carbonate whose solubility also decreases when CO 2 degasses from hot water or can escape out of the system. Coal-fired power station 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, on average capable of generating

2058-402: 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. 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. In Japan, the first major four-year test project

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2156-504: Is an intermediate style step between full multi-coat "wet" plaster and the limited joint-treatment-only given "dry" wall. The method of installation and type of drywall can reduce sound transmission through walls and ceilings. Several builders' books state that thicker drywall reduces sound transmission, but engineering manuals recommend using multiple layers of drywall, sometimes of different thicknesses and glued together, or special types of drywall designed to reduce noise. Also important are

2254-417: Is around 127 million tonnes per annum. In addition to natural sources, calcium sulfate is produced as a by-product in a number of processes: Related sulfur-trapping methods use lime and some produces an impure calcium sulfite , which oxidizes on storage to calcium sulfate. These precipitation processes tend to concentrate radioactive elements in the calcium sulfate product. This issue is particular with

2352-456: 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

2450-502: Is commonly made with one of three edge treatments: tapered edge, where the long edges of the board are tapered with a wide bevel at the front to allow jointing materials to be finished flush with the main board face; plain edge, used where the whole surface will receive a thin coating (skim coat) of finishing plaster; and beveled on all four sides, used in products specialized for roofing. Major UK manufacturers do not offer four-sided chamfered drywall for general use. As an alternative to

2548-556: Is commonly referred to as Gyproc. In Europe , most plasterboard is made in sheets 120 centimetres (47 in) wide; sheets 60 and 90 centimetres (24 and 35 in) wide are also made. Plasterboard 120 centimetres (47 in) wide is most commonly made in 240-centimetre (94 in) lengths; sheets of 250, 260, 270, 280, and 300 centimetres (98, 102, 106, 110, and 118 in) and longer also are common. Thicknesses of plasterboard available are 9.5 to 25 millimetres ( 3 ⁄ 8 to 1 in). Plasterboard

2646-427: 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 CO 2 of

2744-908: Is crucial for evaluating their environmental impacts. In India capacity factors are below 60%. 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. 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. 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. As of 2020 about half of China's coal power companies are losing money and old and small power plants "have no hope of making profits". As of 2021 India

2842-631: Is cut to size by scoring the paper on the finished side (usually white) with a utility knife , breaking the sheet along the cut, and cutting the paper backing. Small features such as holes for outlets and light switches are usually cut using a keyhole saw , oscillating multi-tool or a tiny high-speed bit in a rotary tool. Drywall is then fixed to the structure with nails or drywall screws and often glue. Drywall fasteners , also referred to as drywall clips or stops , are gaining popularity in residential and commercial construction. Drywall fasteners are used for supporting interior drywall corners and replacing

2940-399: 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

3038-575: Is mixed with fiber (typically paper, glass wool , or a combination of these materials); plasticizer , foaming agent ; and additives that can reduce mildew , flammability , and water absorption. In the mid-20th century, drywall construction became prevalent in North America as a time- and labor-saving alternative to lath and plaster . Sackett Board was invented in 1890 by New York Coal Tar Chemical Company employees Augustine Sackett and Fred L. Kane, graduates of Rensselaer Polytechnic Institute . It

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3136-727: Is often called Gyprock , the name of the largest plasterboard manufacturer. In New Zealand it is also called Gibraltar and Gib board , genericised from the registered trademark ("GIB") of the locally made product that dominates the local market. A specific type of Gibraltar board for use in wet conditions (such as bathrooms and kitchens) is known as AquaGib . It is made in thicknesses of 10 mm, 13 mm, and 16 mm, and sometimes other thicknesses up to 25 mm. Panels are commonly sold in 1200 mm-wide sheets, which may be 1800, 2400, 3000, 4800, or 6000 mm in length. Sheets are usually secured to either timber or cold-formed steel frames anywhere from 150 to 300 mm centres along

3234-949: Is often due to burning low quality coal, such as lignite , in plants lacking modern flue gas treatment. 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. Evidence indicates that exposure to sulfur, sulfates, or PM 2.5 from coal emissions may be associated with higher relative morbidity or mortality risk than that to other PM 2.5 constituents or PM 2.5 from other sources per unit concentration. Pollutants such as heavy metals leaching into ground water from unlined coal ash storage ponds or landfills pollute water, possibly for decades or centuries. Pollutant discharges from ash ponds to rivers (or other surface water bodies) typically include arsenic , lead, mercury , selenium , chromium , and cadmium . Mercury emissions from coal-fired power plants can fall back onto

3332-504: Is potential for using crushed drywall to amend certain soils at building sites, such as sodic clay and silt mixtures ( bay mud ), as well as using it in compost. As of 2016, industry standards are being developed to ensure that when and if wallboard is taken back for recycling, quality and composition are maintained. Calcium sulfate The compound exists in three levels of hydration corresponding to different crystallographic structures and to minerals: The main use of calcium sulfate

3430-476: 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

3528-402: Is the risk newer plants may become stranded assets . 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. 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

3626-414: 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, about one fifth of world greenhouse gas emissions , so are the single largest cause of climate change . More than half of all

3724-429: Is to produce plaster of Paris and stucco . These applications exploit the fact that calcium sulfate which has been powdered and calcined forms a moldable paste upon hydration and hardens as crystalline calcium sulfate dihydrate. It is also convenient that calcium sulfate is poorly soluble in water and does not readily dissolve in contact with water after its solidification. With judicious heating, gypsum converts to

3822-697: Is unable to be sold in the US. Some fire barrier walls are constructed of Type X drywall as a passive fire protection item. Gypsum contains the water of crystallization bound in the form of hydrates . When exposed to heat or fire , this water is vaporized, which retards heat transfer until the water in the gypsum is gone. The fire-resistance rating of the fire barrier assembly is increased with additional layers of drywall, up to four hours for walls and three hours for floor/ceiling assemblies. Fire-rated assemblies constructed of drywall are documented in design or certification listing catalogues, including DIN 4102 Part 4 and

3920-405: Is used in aluminothermy . In contrast to most minerals, which when rehydrated simply form liquid or semi-liquid pastes, or remain powdery, calcined gypsum has an unusual property: when mixed with water at normal (ambient) temperatures, it quickly reverts chemically to the preferred dihydrate form, while physically "setting" to form a rigid and relatively strong gypsum crystal lattice: This reaction

4018-444: Is wasted during the manufacturing and installation processes and the drywall material is frequently not reused, disposal can become a problem. Some landfill sites have banned the dumping of drywall. Some manufacturers take back waste wallboard from construction sites and recycle them into new wallboard. Recycled paper is typically used during manufacturing. More recently, recycling at the construction site itself has been researched. There

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4116-723: The Mercury and Air Toxics Standards (MATS) regulation, by effluent guidelines for water pollution , and by solid waste regulations under the Resource Conservation and Recovery Act (RCRA). Coal-fired power stations continue to pollute in lightly regulated countries; such as the Western Balkans , India, Russia and South Africa; causing over a hundred thousand early deaths each year. Damage to health from particulates , sulphur dioxide and nitrogen oxide occurs mainly in Asia and

4214-408: The gypsum part of sheetrock are easily chewed out by honeybees when they are setting up a stray nest in a building, and they want to enlarge their nest area. A substantial amount of defective drywall was imported into the United States from China and incorporated into tens of thousands of homes during rebuilding in 2006 and 2007 following Hurricane Katrina and in other places. Complaints included

4312-568: The 34 Gt total from fuel combustion (the overall total greenhouse gas emissions for 2018 was 55 Gt CO 2 e ). From 2015 to 2020, although coal generation hardly fell in absolute terms, some of its market share was taken by wind and solar. In 2020 only China increased coal power generation, and globally it fell by 4%. However, in 2021, China declared that it limited coal generation until 2025 and subsequently phase it out over time. The UN Secretary General has said that OECD countries should stop generating electricity from coal by 2030 and

4410-476: The Canadian Building Code, Underwriters Laboratories and Underwriters Laboratories of Canada (ULC). Tests result in code-recognized designs with assigned fire-resistance ratings. The resulting designs become part of the code and are not limited to use by any manufacturer. However, individual manufacturers may also have proprietary designs that they have had third-party tested and approved, provided that

4508-634: The Global Coal to Clean Power pledge. However, intricate challenges remain, particularly in developing countries such as Indonesia and Vietnam. 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). 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. Integrated gasification combined cycle (IGCC)

4606-493: The U.S. alone, such particulates, known as PM 2.5 (particulates with a diameter of 2.5 μm or less), caused at least 460,000 excess deaths over two decades. In some countries pollution is somewhat controlled by best available techniques , for example those in the EU through its Industrial Emissions Directive . In the United States, coal-fired plants are governed at the national level by several air pollution regulations, including

4704-648: The UK, Germany and the Benelux countries. A wallboard panel consists of a layer of gypsum plaster sandwiched between two layers of paper . The raw gypsum , CaSO 4 ·2H 2 O , is heated to drive off the water and then slightly rehydrated to produce the hemihydrate of calcium sulfate ( CaSO 4 · ⁠ 1 / 2 ⁠ H 2 O ). The plaster is mixed with fiber (typically paper and/or glass fiber ), plasticizer , foaming agent , finely ground gypsum crystal as an accelerator, EDTA , starch or other chelate as

4802-458: The affected drywall. They use rapid drying techniques that eliminate the elements required to support microbial activity while restoring most or all of the drywall. It is for these reasons that greenboard , a type of drywall with an outer face that is wax- and/or chemically coated to resist mold growth, and ideally cement board are used for rooms expected to have high humidity, primarily kitchens, bathrooms, and laundry rooms. Foam insulation and

4900-440: The area of implantation. When sold at the anhydrous state as a desiccant with a color-indicating agent under the name Drierite , it appears blue (anhydrous) or pink (hydrated) due to impregnation with cobalt(II) chloride , which functions as a moisture indicator. Up to the 1970s, commercial quantities of sulfuric acid were produced from anhydrous calcium sulfate. Upon being mixed with shale or marl , and roasted at 1400°C,

4998-448: The beam and 400 to 600 mm across members. In both countries, plasterboard has become a widely used replacement for scrim and sarking walls in renovating 19th- and early 20th-century buildings. Drywall panels in Canada and the United States are made in widths of 48, 54, and 96 inches (1.2, 1.4, and 2.4 m) and varying lengths to suit the application. The most common width

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5096-458: The board—introduced during manufacturing to reduce the board's weight, lowering construction time and transportation costs—enables water to rapidly reach the core through capillary action , where mold can grow inside. Water that enters a room from overhead may cause ceiling drywall tape to separate from the ceiling as a result of the grooves immediately behind the tape where the drywall pieces meet becoming saturated. The drywall may also soften around

5194-529: 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. Although technically

5292-485: The calcination of the gypsum in the core, allowing the core of the Type C panels to remain dimensionally stable in a fire. North America is one of the largest gypsum board users in the world, with a total wallboard plant capacity of 42 billion square feet (3.9 billion square metres) per year, roughly half of the worldwide annual production capacity of 85 billion square feet (7.9 billion square metres). Moreover,

5390-421: 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

5488-641: 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

5586-469: 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

5684-406: The coal to the boiler furnace and preheats the coal in order to drive off excess moisture content. A 500 MW e 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

5782-450: The coal-fired electricity in the world is generated in China. In 2020 the total number of plants started falling as they are being retired in Europe and America although still being built in Asia, almost all in China. 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, but there

5880-543: The collapse of fish and invertebrate populations. 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. 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

5978-495: The completely anhydrous form called β-anhydrite or "natural" anhydrite is formed. Natural anhydrite does not react with water, even over geological timescales, unless very finely ground. The variable composition of the hemihydrate and γ-anhydrite, and their easy inter-conversion, is due to their nearly identical crystal structures containing "channels" that can accommodate variable amounts of water, or other small molecules such as methanol . The calcium sulfate hydrates are used as

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6076-428: The construction details of the framing with steel studs, wider stud spacing, double studding, insulation, and other details reducing sound transmission. Sound transmission class (STC) ratings can be increased from 33 for an ordinary stud-wall to as high as 59 with double 1 ⁄ 2 -inch (13 mm) drywall on both sides of a wood stud wall with resilient channels on one side and glass wool batt insulation between

6174-425: The conventional conical countersunk head; this compresses the drywall surface rather than cutting into it and so avoids tearing the paper. Screws for light-gauge steel framing have a sharp point and finely spaced threads. If the steel framing is heavier than 20- gauge , self-drilling screws with finely spaced threads must be used. In some applications, the drywall may be attached to the wall with adhesives . After

6272-446: 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

6370-402: 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; however, some flexibility improvements may be more expensive than renewable energy with batteries . As of 2020 two-thirds of coal burned is to generate electricity. In 2020 coal was

6468-445: 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. Power utility companies have often built

6566-407: 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. 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

6664-431: The gypsum at this time (the heat of hydration) tends to go into driving off water (as water vapor) rather than increasing the temperature of the mineral, which rises slowly until the water is gone, then increases more rapidly. The equation for the partial dehydration is: The endothermic property of this reaction is relevant to the performance of drywall , conferring fire resistance to residential and other structures. In

6762-403: The gypsum panels resist fire without failure. Type C gypsum panels provide stronger fire resistance than Type X. The core of Type C panels contains a higher density of glass fibers. The core of Type C panels also contains vermiculite which acts as a shrinkage-compensating additive that expands when exposed to elevated temperatures of a fire. This expansion occurs at roughly the same temperature as

6860-732: The homebuilding and remodeling markets in North America in the late 1990s and early 2000s increased demand. The gypsum board market was one of the biggest beneficiaries of the housing boom as "an average new American home contains more than 7.31 metric tons of gypsum." The introduction in March 2005 of the Clean Air Interstate Rule by the United States Environmental Protection Agency requires fossil-fuel power plants to "cut sulfur dioxide emissions by 73%" by 2018. The Clean Air Interstate Rule also requested that

6958-434: The joints and cover the fastener heads with drywall compound . Drywall can be finished anywhere from a level 0 to a level 5, where 0 is not finished in any fashion, and five is the most pristine. Depending on how significant the finish is to the customer, the extra steps in the finish may or may not be necessary, though priming and painting of drywall are recommended in any location where it may be exposed to any wear. Drywall

7056-402: The land and water in rain, and then be converted into methylmercury by bacteria. Through biomagnification , this mercury can then reach dangerously high levels in fish. More than half of atmospheric mercury comes from coal-fired power plants. Coal-fired power plants also emit sulfur dioxide and nitrogen . These emissions lead to acid rain , which can restructure food webs and lead to

7154-560: The largest source of electricity at 34%. Over half coal generation in 2020 was in China. About 60% of electricity in China, India and Indonesia is from coal. 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). In 2023, global coal power capacity increased to 2,130 GW, driven by China adding 47.4 GW. At COP26 2021, countries have joined

7252-454: 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. In 2020 the coal industry was subsidized $ US18 billion. Coal financing is the financial support provided for coal-related projects, encompassing coal mining and coal-fired power stations. Its role in shaping

7350-406: The material used in the field configuration can be demonstrated to meet the minimum requirements of Type X drywall and that sufficient layers and thicknesses are used. In the Type X gypsum board, special glass fibers are intermixed with the gypsum to reinforce the core of the panels. These fibers reduce the size of the cracks that form as the water is driven off, thereby extending the length of time

7448-446: The materials that constitute it: gypsum, paper, and organic additives and binders. Gypsum will soften with exposure to moisture and eventually turn into a gooey paste with prolonged immersion, such as during a flood. During such incidents, some, or all, of the drywall in an entire building will need to be removed and replaced. Furthermore, the paper facings and organic additives mixed with the gypsum core are food for mold. The porosity of

7546-426: The necessity of patching the damaged surface and repainting, if enough of the paper has been eaten, the gypsum core can easily crack or crumble without it, and the drywall must be removed and replaced. In many circumstances, especially when the drywall has been exposed to water or moisture for less than 48 hours, professional restoration experts can avoid the cost, inconvenience, and difficulty of removing and replacing

7644-417: The non-structural wood or metal blocking that traditionally was used to install drywall. Their function saves material and labor costs, minimizes call-backs due to truss uplift , increases energy efficiency , and makes plumbing and electrical installation simpler. When driven fully home, drywall screws countersink their heads slightly into the drywall. They use a 'bugle head', a concave taper, rather than

7742-611: 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 CO 2 emissions is anticipated to occur after 2019. Coal financing poses challenges to the global decarbonization of the power generation sector. As renewable energy technologies become cost-competitive, the economic viability of coal projects diminishes, making past fossil fuel investments less attractive. To address these concerns and align with climate goals, there

7840-508: The partially dehydrated mineral called bassanite or plaster of Paris . This material has the formula CaSO 4 ·( n H 2 O), where 0.5 ≤ n ≤ 0.8. Temperatures between 100 and 150 °C (212–302 °F) are required to drive off the water within its structure. The details of the temperature and time depend on ambient humidity. Temperatures as high as 170 °C (338 °F) are used in industrial calcination, but at these temperatures γ-anhydrite begins to form. The heat energy delivered to

7938-428: The phosphate by-product, since phosphate ores naturally contain uranium and its decay products such as radium-226 , lead-210 and polonium-210 . Extraction of uranium from phosphorus ores can be economical on its own depending on prices on the uranium market or the separation of uranium can be mandated by environmental legislation and its sale is used to recover part of the cost of the process. Calcium sulfate

8036-573: 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

8134-491: The ponds without liners , especially in the United States, and therefore chemicals in the ash can leach into groundwater and surface waters. 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. Dry ash may also be recycled into products such as concrete, structural fills for road construction and grout. Fly ash

8232-431: The porosity of the hemihydrate, resulting in the so-called α- and β-hemihydrates (which are more or less chemically identical). On heating to 180 °C (356 °F), the nearly water-free form, called γ-anhydrite (CaSO 4 · n H 2 O where n = 0 to 0.05) is produced. γ-Anhydrite reacts slowly with water to return to the dihydrate state, a property exploited in some commercial desiccants . On heating above 250 °C,

8330-479: The power plants install new scrubbers (industrial pollution control devices) to remove sulfur dioxide present in the output waste gas. Scrubbers use the technique of flue-gas desulfurization (FGD), which produces synthetic gypsum as a usable by-product. In response to the new supply of this raw material, the gypsum board market was predicted to shift significantly. However, issues such as mercury release during calcining need to be resolved. Because up to 12% of drywall

8428-441: 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. A 2024 analysis by The Economist concluded that financing phase-out would be cheaper than carbon offsets . However phasing out in Asia can be a financial challenge as plants there are relatively young: in China the co-benefits of closing a plant vary greatly depending on its location. Vietnam

8526-407: The screws holding the drywall in place, and with the aid of gravity, the weight of the water may cause the drywall to sag and eventually collapse, requiring replacement. Drywall's paper facings are edible to termites, which can eat the paper if they infest a wall cavity covered with drywall. This causes the painted surface to crumble to the touch, its paper backing material being eaten. In addition to

8624-427: The setting of the gypsum plaster component. This setting has far less shrinkage than the air-dry compounds normally used in drywall, so it only requires one coat. Blueboard also has square edges rather than tapered-edge drywall boards. The tapered drywall boards are used to countersink the tape in taped jointing, whereas the tape in veneer plastering is buried beneath a level surface. One coat veneer plaster over dry board

8722-416: The sheets are secured to the wall studs or ceiling joists , the installer conceals the seams between drywall sheets with joint tape or fiber mesh. Layers of joint compound, sometimes called mud, are typically spread with a drywall trowel or knife. This compound is also applied to any screw holes or defects. The compound is allowed to air dry and then typically sanded smooth before painting. Alternatively, for

8820-625: The sheets of drywall are simply marked "Made in China", thus making the manufacturer's identification difficult. An investigation by the Consumer Product Safety Commission , CPSC, was underway in 2009. In November 2009, the CPSC reported a "strong association" between Chinese drywall and corrosion of pipes and wires reported by thousands of homeowners in the United States. The issue was resolved in 2011, and now all drywall must be tested for volatile sulfur, and any containing more than ten ppm

8918-542: The structure's foul odour, health effects, and metal corrosion. The emission of sulfurous gases causes this. The same drywall was sold in Asia without problems resulting, but US homes are built much more tightly than homes in China, with less ventilation. Volatile sulfur compounds, including hydrogen sulfide , have been detected as emissions from the imported drywall and may be linked to health problems. These compounds are emitted from many different types of drywall. Several lawsuits are underway in many jurisdictions, but many of

9016-410: The studs. Sound transmission may be slightly reduced using regular 5 ⁄ 8 -inch (16 mm) panels (with or without light-gauge resilient metal channels and/or insulation), but it is more effective to use two layers of drywall, sometimes in combination with other factors, or specially designed, sound-resistant drywall. Drywall is highly vulnerable to moisture due to the inherent properties of

9114-466: The sulfate liberates sulfur dioxide gas, a precursor to sulfuric acid . The reaction also produces calcium silicate , used in cement clinker production. Some component reactions pertaining to calcium sulfate: The main sources of calcium sulfate are naturally occurring gypsum and anhydrite , which occur at many locations worldwide as evaporites . These may be extracted by open-cast quarrying or by deep mining. World production of natural gypsum

9212-452: Was being considered in China in 2020, but this is very expensive, reduces the energy output and for some plants is not technically feasible. 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

9310-455: Was developed additionally as a measure of fire resistance. Later air entrainment technology made boards lighter and less brittle, and joint treatment materials and systems also evolved. Gypsum lath was an early substrate for plaster. An alternative to traditional wood or metal lath was a panel made up of compressed gypsum plaster board that was sometimes grooved or punched with holes to allow wet plaster to key into its surface. As it evolved, it

9408-510: Was faced with paper impregnated with gypsum crystals that bonded with the applied facing layer of plaster. In 1936, US Gypsum trademarked ROCKLATH for their gypsum lath product. In 2002 the European Commission imposed fines totaling €420 million on the companies Lafarge , BPB , Knauf and Gyproc Benelux, which had operated a cartel on the market which affected 80% of consumers in France ,

9506-523: Was made by layering plaster within four plies of wool felt paper. Sheets were 36 by 36 by 1 ⁄ 4 inch (914 mm × 914 mm × 6 mm) thick with open (untaped) edges. Gypsum board evolved between 1910 and 1930, beginning with wrapped board edges and the elimination of the two inner layers of felt paper in favor of paper-based facings. In 1910 United States Gypsum Corporation bought Sackett Plaster Board Company and by 1917 introduced Sheetrock . Providing installation efficiency, it

9604-568: 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. However low-carbon hydrogen and ammonia is in demand for sustainable shipping , which unlike electricity generation, has few other clean options. Some power stations are being converted to burn gas, biomass or waste, and conversion to thermal storage will be trialled in 2023. Retrofitting some existing coal-fired power stations with carbon capture and storage

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