reboundnd effect
Further information: Rebound effect (conservation) and Jevons' paradox
If the demand for energy services remains constant, improving energy efficiency will reduce energy consumption and carbon emissions. However, many efficiency improvements do not reduce energy consumption by the amount predicted by simple engineering models. This is because they make energy services cheaper, and so consumption of those services increase. For example, since fuel efficient vehicles make travel cheaper, consumers may choose to drive further and/or faster, thereby offsetting some of the potential energy savings. This is an example of the direct rebound effect.[20]
Estimates of the size of the rebound effect range from roughly 5% to 40%.[21][22][23] Rebound effects are smaller in mature markets where demand is saturated. The rebound effect is likely to be less than 30% at the household level and may be closer to 10% for transport.[20] A rebound effect of 30% implies that improvements in energy efficiency should achieve 70% of the reduction in energy consumption projected using engineering models.
Thursday, November 12, 2009
Sustainable energy
: Sustainable energy
Energy efficiency and renewable energy are said to be the “twin pillars” of a sustainable energy policy. Both strategies must be developed concurrently in order to stabilize and reduce carbon dioxide emissions. Efficient energy use is essential to slowing the energy demand growth so that rising clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too rapidly, renewable energy development will chase a receding target. Likewise, unless clean energy supplies come online rapidly, slowing demand growth will only begin to reduce total carbon emissions; a reduction in the carbon content of energy sources is also needed. A sustainable energy economy thus requires major commitments to both efficiency and renewables.[19
Energy efficiency and renewable energy are said to be the “twin pillars” of a sustainable energy policy. Both strategies must be developed concurrently in order to stabilize and reduce carbon dioxide emissions. Efficient energy use is essential to slowing the energy demand growth so that rising clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too rapidly, renewable energy development will chase a receding target. Likewise, unless clean energy supplies come online rapidly, slowing demand growth will only begin to reduce total carbon emissions; a reduction in the carbon content of energy sources is also needed. A sustainable energy economy thus requires major commitments to both efficiency and renewables.[19
Energy conservation
Energy conservation
Energy conservation is broader than energy efficiency in that it encompasses using less energy to achieve a lesser energy service, for example through behavioural change, as well as encompassing energy efficiency. Examples of conservation without efficiency improvements would be heating a room less in winter, driving less, or working in a less brightly lit room. As with other definitions, the boundary between efficient energy use and energy conservation can be fuzzy, but both are important in environmental and economic terms. This is especially the case when actions are directed at the saving of fossil fuels.[1
Energy conservation is broader than energy efficiency in that it encompasses using less energy to achieve a lesser energy service, for example through behavioural change, as well as encompassing energy efficiency. Examples of conservation without efficiency improvements would be heating a room less in winter, driving less, or working in a less brightly lit room. As with other definitions, the boundary between efficient energy use and energy conservation can be fuzzy, but both are important in environmental and economic terms. This is especially the case when actions are directed at the saving of fossil fuels.[1
fuel energy
Fuel efficient vehicles may reach twice the fuel efficiency of the average automobile. Cutting-edge designs, such as the diesel Mercedes-Benz Bionic concept vehicle have achieved a fuel efficiency as high as 84 miles per US gallon (2.8 L/100 km; 101 mpg-imp), four times the current conventional automotive average.[16].
Another growing trend in automotive efficiency is the rise of hybrid and electric cars. Hybrids, like the Toyota Prius, use regenerative braking to recapture energy that would dissipate in normal cars; the effect is especially pronounced in city driving. plug-in hybrids also have increased battery capacity, which makes it possible to drive for limited distances without burning any gasoline; in this case, energy efficiency is dictated by whatever process (coal-burning, hydroelectric, etc) created the power. Plug-ins can typically drive for around 40 mile purely on electricity without recharging; if the battery runs low, a gas engine kicks in allowing for extended range. Finally, all-electric cars are also growing in popularity; the Tesla Roadster sports car is
Another growing trend in automotive efficiency is the rise of hybrid and electric cars. Hybrids, like the Toyota Prius, use regenerative braking to recapture energy that would dissipate in normal cars; the effect is especially pronounced in city driving. plug-in hybrids also have increased battery capacity, which makes it possible to drive for limited distances without burning any gasoline; in this case, energy efficiency is dictated by whatever process (coal-burning, hydroelectric, etc) created the power. Plug-ins can typically drive for around 40 mile purely on electricity without recharging; if the battery runs low, a gas engine kicks in allowing for extended range. Finally, all-electric cars are also growing in popularity; the Tesla Roadster sports car is
modern energy
The impact of energy efficiency on peak demand depends on when the appliance is used.[12] For example, an air conditioner uses more energy during the afternoon when it is hot. Therefore, an energy efficient air conditioner will have a larger impact on peak demand than off-peak demand. An energy efficient dishwasher, on the other hand, uses more energy during the late evening when people do their dishes. This appliance may have little to no impact on peak demand.
eu energy
EU energy label.png
See also: green computing, solar lamp, energy saving lamp, and power usage effectiveness
Modern energy-efficient appliances, such as refrigerators, freezers, ovens, stoves, dishwashers, and clothes washers and dryers, use significantly less energy than older appliances. Current energy efficient refrigerators, for example, use 40 percent less energy than conventional models did in 2001. Following this, if all households in Europe changed their more than ten year old appliances into new ones, 20 billion kWh of electricity would be saved annually, hence reducing CO2 emissions by almost 18 billion kg.[8] In the US, the corresponding figures would be 17 billion kWh of electricity and 27,000,000,000 lb (1.2×1010 kg) CO2.[9] According to a 2009 study from McKinsey & Company the replacement of old appliances is one of the most efficient global measures to reduce emissions of greenhouse gases.[10] Modern power management systems also reduce energy usage by idle appliances by turning them off or putting them into a low-energy mode after a certain time. Many countries identify energy-efficient appliances using an Energy Star label.[11]
See also: green computing, solar lamp, energy saving lamp, and power usage effectiveness
Modern energy-efficient appliances, such as refrigerators, freezers, ovens, stoves, dishwashers, and clothes washers and dryers, use significantly less energy than older appliances. Current energy efficient refrigerators, for example, use 40 percent less energy than conventional models did in 2001. Following this, if all households in Europe changed their more than ten year old appliances into new ones, 20 billion kWh of electricity would be saved annually, hence reducing CO2 emissions by almost 18 billion kg.[8] In the US, the corresponding figures would be 17 billion kWh of electricity and 27,000,000,000 lb (1.2×1010 kg) CO2.[9] According to a 2009 study from McKinsey & Company the replacement of old appliances is one of the most efficient global measures to reduce emissions of greenhouse gases.[10] Modern power management systems also reduce energy usage by idle appliances by turning them off or putting them into a low-energy mode after a certain time. Many countries identify energy-efficient appliances using an Energy Star label.[11]
Saturday, November 7, 2009
Opencast coal mine at Cerrejón
Opencast coal mine at Cerrejón
Some of the world's largest coal reserves are located in South America, and an opencast mine at Cerrejón in Colombia is one of the world's largest open pit mines. Output of the mine in 2004 was 24.9 million tons (compared to total global hard coal production of 4,600 million tons). Cerrejón contributed about half of Colombia's coal exports of 52 million tons that year, with Colombia ranked sixth among major coal exporting nations. The company planned to expand production to 32 million tons by 2008.
Some of the world's largest coal reserves are located in South America, and an opencast mine at Cerrejón in Colombia is one of the world's largest open pit mines. Output of the mine in 2004 was 24.9 million tons (compared to total global hard coal production of 4,600 million tons). Cerrejón contributed about half of Colombia's coal exports of 52 million tons that year, with Colombia ranked sixth among major coal exporting nations. The company planned to expand production to 32 million tons by 2008.
coal-loading
The company has its own 150 km standard-gauge railroad, connecting the mine to its coal-loading terminal at Puerto Bolívar on the Caribbean coast. There are two 120-car unit trains, each carrying 12,000 tons of coal per trip. The round-trip time for each train, including loading and unloading, is about 12 hours. The coal facilities at the port are capable of loading 4,800 tons per hour on to vessels of up to 175,000 tons of dead weight. The mine, railroad and port operate 24 hours per day. Cerrejón directly employs 4,600 workers, with a further 3,800 employed by contractors. The reserves at Cerrejón are low-sulfur, low-ash, bituminous coal. The coal is mostly used for electric power generation, with some also used in steel manufacture. The surface mineable reserves for the current contract are 330 million tons. However, total proven reserves to a depth of 300 metres are 3,000 million
economic and technical
The limitations on contour strip mining are both economic and technical. When the operation reaches a predetermined stripping ratio (tons of overburden/tons of coal), it is not profitable to continue. Depending on the equipment available, it may not be technically feasible to exceed a certain height of highwall. At this point, it is possible to produce more coal with the augering method in which spiral drills bore tunnels into a highwall laterally from the bench to extract coal without removing the overburden.[4] Mountaintop removal mining
Main article: Mountaintop removal
Mountaintop coal mining is a surface mining practice involving removal of mountaintops to expose coal seams, and disposing of associated mining overburden in adjacent "valley fills." Valley fills occur in steep terrain where there are limited disposal alternatives. Mountaintop removal combines area and contour strip mining methods. In areas with rolling or steep terrain with a coal seam occurring near the top of a ridge or hill, the entire top is removed in a series of parallel cuts. Overburden is deposited in nearby valleys and hollows. This method usually leaves ridge and hill tops as flattened plateaus.[4] The process is highly controversial for the drastic changes in topography, the practice of creating head-of-hollow-fills, or filling in valleys with mining debris, and for covering streams and disrupting ecosystems.[9][10]
Spoil is placed at the head of a narrow, steep-sided valley or hollow. In preparation for filling this area, vegetation and soil are removed and a rock drain constructed down the middle of the area to be filled, Underground mining
Main article: Underground mining (soft rock)
Coal wash plant in Clay County, Kentucky.
Most coal seams are too deep underground for opencast mining and require underground mining, which method currently accounts for about 60% of world coal production.[13] In deep mining, the room and pillar or bord and pillar method progresses along the seam, while pillars and timber are left standing to support the mine roof. Once room and pillar mines have been developed to a stopping point (limited by geology, ventilation, or economics), a supplementary version of room and pillar mining, termed second mining or retreat mining, is commonly started. Miners remove the coal in the pillars, thereby recovering as much coal from the coal seam as possible. A work area involved in pillar extraction is called a pillar section. Modern pillar sections use remote-controlled equipment, including large hydraulic mobile roof-supports, which can prevent cave-ins until the miners and their equipment have left a work area. The mobile roof supports are similar to a large dining-room table, but with hydraulic jacks for legs. After the large pillars of coal have been mined away, the mobile roof support's legs shorten and it is withdrawn to a safe area. The mine roof typically collapses once the mobile roof supports leave an area.
There are five principal methods of underground mining:
* Longwall mining accounts for about 50% of underground production. The longwall shearer has a face of 1,000 feet (300 m) or more. It is a sophisticated machine with a rotating drum that moves mechanically back and forth across a wide coal seam. The loosened coal falls on to a pan line that takes the coal to the conveyor belt for removal from the work area. Longwall systems have their own hydraulic roof supports which advance with the machine as mining progresses. As the longwall mining equipment moves forward, overlying rock that is no longer supported by coal is allowed to fall behind the operation in a controlled manner. The supports make possible high levels of production and safety. Sensors detect how much coal remains in the seam while robotic controls enhance efficiency. Longwall systems allow a 60-to-100% coal recovery rate when surrounding geology allows their use. Once the coal is removed, usually 75 percent of the section, the roof is allowed to collapse in a safe manner.[14]
* Continuous mining utilizes a machine with a large rotating steel drum equipped with tungsten carbide teeth that scrape coal from the seam. Operating in a “room and pillar” (also known as “bord and pillar”) system—where the mine is divided into a series of 20-to-30 foot “rooms” or work areas cut into the coalbed—it can mine as much as five tons of coal a minute, more than a non-mechanised miner of the 1920s would produce in an entire day. Continuous miners account for about 45% of underground coal production. Conveyors transport the removed coal from the seam. Remote-controlled continuous miners are used to work in a variety of difficult seams and conditions, and robotic versions controlled by computers are becoming increasingly common.
* Blast mining is an older practice that uses explosives such as dynamite to break up the coal seam, after which the coal is gathered and loaded on to shuttle cars or conveyors for removal to a central loading area. This process consists of a series of operations that begins with “cutting” the coalbed so it will break easily when blasted with explosives. This type of mining accounts for less than 5% of total underground production in the U.S. today.
* Shortwall mining, a method currently accounting for less than 1% of deep coal production, involves the use of a continuous mining machine with movable roof supports, similar to longwall. The continuous miner shears coal panels 150-200 feet wide and more than a half-mile long, having regard to factors such as geological strata.
* Retreat mining is a method in which the pillars or coal ribs used to hold up the mine roof are extracted; allowing the mine roof to collapse as the mining works back towards the entrance. This is one of the most dangerous forms of mining owing to imperfect predictability of when the ceiling will collapse and possibly crush or trap workers in the mine.
where a natural drainage course previously existed. When the fill is completed, this underdrain will form a continuous water runoff system from the upper end of the valley to the lower end of the fill. Typical head-of-hollow fills are graded and terraced to create permanently stable slopes.[11]
angers to miners
Historically, coal mining has been a very dangerous activity and the list of historical coal mining disasters is a long one. Open cut hazards are principally mine wall failures and vehicle collisions; underground mining hazards include suffocation, gas poisoning, roof collapse and gas explosions. Most of these risks can be greatly reduced in modern mines, and multiple fatality incidents are now rare in some parts of the developed world.[19]
However, in lesser developed countries and some developed countries, many miners continue to die annually, either through direct accidents in coal mines or through adverse health consequences from working under poor conditions. China, in particular, has the highest number of coal mining related deaths in the world, with official statistic 6,027 deaths in 2004.[20] To compare, 28 deaths were reported in the U.S. in the same year.[21] Coal production in China is twice that in the U.S.,[22] while the number of coal miners is around 50 times that of the USA, making deaths in coal mines in China 4 times as common per worker (108 times as common per unit output) as in the USA.
When compared to industrial countries such as China, the fatality rate is low in the U.S.[specify] However, in 2006, fatal work injuries among miners in the U.S. doubled from the previous year, totaling 47.[23] These figures can in part be attributed to the Sago Mine disaster. The recent mine accident in Utah's Crandall Canyon Mine, where nine miners were killed and six entombed, speaks to the increase in occupational risks faced by U.S. miners.[24]
Chronic lung diseases, such as pneumoconiosis (black lung) were once common in miners, leading to reduced life expectancy. In some mining countries black lung is still common, with 4000 new cases of black lung every year in the USA (4% of workers annually) and 10 000 new cases every year in China (0.2% of workers).[25] Rates may be higher than reported in some regions.
Build-ups of a hazardous gas are known as damps, possibly from the German word "Dampf" which means steam or vapor:
* Black damp: a mixture of carbon dioxide and nitrogen in a mine can cause suffocation.
* After damp: similar to black damp, an after damp consists of carbon dioxide and nitrogen and forms after a mine explosion.
* Fire damp: consists of mostly methane, a flammable gas. China
Wiki letter w.svg This section requires expansion.
Main article: Coal power in China
The People's Republic of China is by far the largest producer of coal in the world, producing over 2.8 billion tons of coal in 2007, or approximately 39.8 percent of all coal produced in the world during that year.[15] For comparison, the second largest producer, the United States, produced more than 1.1 billion tons in 2007. An estimated 5 million people work in China's coal-mining industry. As many as 20,000 miners die in accidents each year.[30]
Most Chinese mines are deep underground and do not produce the surface disruption typical of strip mines. Although there is some evidence of reclamation of mined land for use as parks, China does not require extensive reclamation and is creating significant acreages of abandoned mined land which is unsuitable for agriculture or other human uses, and inhospitable to indigenous wildlife. Chinese underground mines often experience severe surface subsidence (6-12 meters), negatively impacting farmland because it no longer drains well. China uses some subsidence areas for aquaculture ponds but has more than they need for that purpose. Reclamation of subsided ground is a significant problem in China.
Because most Chinese coal is for domestic consumption and is burned with little or no air pollution control equipment, it contributes greatly to visible smoke and severe air pollution in industrial areas using coal for fuel. Air pollution control equipment is being installed on some plants, but there are unconfirmed reports it is only turned on when inspectors visit. China's carbon dioxide emissions may increase 30% in 2008 due to increased coal combustion.[citation needed]
Main article: Mountaintop removal
Mountaintop coal mining is a surface mining practice involving removal of mountaintops to expose coal seams, and disposing of associated mining overburden in adjacent "valley fills." Valley fills occur in steep terrain where there are limited disposal alternatives. Mountaintop removal combines area and contour strip mining methods. In areas with rolling or steep terrain with a coal seam occurring near the top of a ridge or hill, the entire top is removed in a series of parallel cuts. Overburden is deposited in nearby valleys and hollows. This method usually leaves ridge and hill tops as flattened plateaus.[4] The process is highly controversial for the drastic changes in topography, the practice of creating head-of-hollow-fills, or filling in valleys with mining debris, and for covering streams and disrupting ecosystems.[9][10]
Spoil is placed at the head of a narrow, steep-sided valley or hollow. In preparation for filling this area, vegetation and soil are removed and a rock drain constructed down the middle of the area to be filled, Underground mining
Main article: Underground mining (soft rock)
Coal wash plant in Clay County, Kentucky.
Most coal seams are too deep underground for opencast mining and require underground mining, which method currently accounts for about 60% of world coal production.[13] In deep mining, the room and pillar or bord and pillar method progresses along the seam, while pillars and timber are left standing to support the mine roof. Once room and pillar mines have been developed to a stopping point (limited by geology, ventilation, or economics), a supplementary version of room and pillar mining, termed second mining or retreat mining, is commonly started. Miners remove the coal in the pillars, thereby recovering as much coal from the coal seam as possible. A work area involved in pillar extraction is called a pillar section. Modern pillar sections use remote-controlled equipment, including large hydraulic mobile roof-supports, which can prevent cave-ins until the miners and their equipment have left a work area. The mobile roof supports are similar to a large dining-room table, but with hydraulic jacks for legs. After the large pillars of coal have been mined away, the mobile roof support's legs shorten and it is withdrawn to a safe area. The mine roof typically collapses once the mobile roof supports leave an area.
There are five principal methods of underground mining:
* Longwall mining accounts for about 50% of underground production. The longwall shearer has a face of 1,000 feet (300 m) or more. It is a sophisticated machine with a rotating drum that moves mechanically back and forth across a wide coal seam. The loosened coal falls on to a pan line that takes the coal to the conveyor belt for removal from the work area. Longwall systems have their own hydraulic roof supports which advance with the machine as mining progresses. As the longwall mining equipment moves forward, overlying rock that is no longer supported by coal is allowed to fall behind the operation in a controlled manner. The supports make possible high levels of production and safety. Sensors detect how much coal remains in the seam while robotic controls enhance efficiency. Longwall systems allow a 60-to-100% coal recovery rate when surrounding geology allows their use. Once the coal is removed, usually 75 percent of the section, the roof is allowed to collapse in a safe manner.[14]
* Continuous mining utilizes a machine with a large rotating steel drum equipped with tungsten carbide teeth that scrape coal from the seam. Operating in a “room and pillar” (also known as “bord and pillar”) system—where the mine is divided into a series of 20-to-30 foot “rooms” or work areas cut into the coalbed—it can mine as much as five tons of coal a minute, more than a non-mechanised miner of the 1920s would produce in an entire day. Continuous miners account for about 45% of underground coal production. Conveyors transport the removed coal from the seam. Remote-controlled continuous miners are used to work in a variety of difficult seams and conditions, and robotic versions controlled by computers are becoming increasingly common.
* Blast mining is an older practice that uses explosives such as dynamite to break up the coal seam, after which the coal is gathered and loaded on to shuttle cars or conveyors for removal to a central loading area. This process consists of a series of operations that begins with “cutting” the coalbed so it will break easily when blasted with explosives. This type of mining accounts for less than 5% of total underground production in the U.S. today.
* Shortwall mining, a method currently accounting for less than 1% of deep coal production, involves the use of a continuous mining machine with movable roof supports, similar to longwall. The continuous miner shears coal panels 150-200 feet wide and more than a half-mile long, having regard to factors such as geological strata.
* Retreat mining is a method in which the pillars or coal ribs used to hold up the mine roof are extracted; allowing the mine roof to collapse as the mining works back towards the entrance. This is one of the most dangerous forms of mining owing to imperfect predictability of when the ceiling will collapse and possibly crush or trap workers in the mine.
where a natural drainage course previously existed. When the fill is completed, this underdrain will form a continuous water runoff system from the upper end of the valley to the lower end of the fill. Typical head-of-hollow fills are graded and terraced to create permanently stable slopes.[11]
angers to miners
Historically, coal mining has been a very dangerous activity and the list of historical coal mining disasters is a long one. Open cut hazards are principally mine wall failures and vehicle collisions; underground mining hazards include suffocation, gas poisoning, roof collapse and gas explosions. Most of these risks can be greatly reduced in modern mines, and multiple fatality incidents are now rare in some parts of the developed world.[19]
However, in lesser developed countries and some developed countries, many miners continue to die annually, either through direct accidents in coal mines or through adverse health consequences from working under poor conditions. China, in particular, has the highest number of coal mining related deaths in the world, with official statistic 6,027 deaths in 2004.[20] To compare, 28 deaths were reported in the U.S. in the same year.[21] Coal production in China is twice that in the U.S.,[22] while the number of coal miners is around 50 times that of the USA, making deaths in coal mines in China 4 times as common per worker (108 times as common per unit output) as in the USA.
When compared to industrial countries such as China, the fatality rate is low in the U.S.[specify] However, in 2006, fatal work injuries among miners in the U.S. doubled from the previous year, totaling 47.[23] These figures can in part be attributed to the Sago Mine disaster. The recent mine accident in Utah's Crandall Canyon Mine, where nine miners were killed and six entombed, speaks to the increase in occupational risks faced by U.S. miners.[24]
Chronic lung diseases, such as pneumoconiosis (black lung) were once common in miners, leading to reduced life expectancy. In some mining countries black lung is still common, with 4000 new cases of black lung every year in the USA (4% of workers annually) and 10 000 new cases every year in China (0.2% of workers).[25] Rates may be higher than reported in some regions.
Build-ups of a hazardous gas are known as damps, possibly from the German word "Dampf" which means steam or vapor:
* Black damp: a mixture of carbon dioxide and nitrogen in a mine can cause suffocation.
* After damp: similar to black damp, an after damp consists of carbon dioxide and nitrogen and forms after a mine explosion.
* Fire damp: consists of mostly methane, a flammable gas. China
Wiki letter w.svg This section requires expansion.
Main article: Coal power in China
The People's Republic of China is by far the largest producer of coal in the world, producing over 2.8 billion tons of coal in 2007, or approximately 39.8 percent of all coal produced in the world during that year.[15] For comparison, the second largest producer, the United States, produced more than 1.1 billion tons in 2007. An estimated 5 million people work in China's coal-mining industry. As many as 20,000 miners die in accidents each year.[30]
Most Chinese mines are deep underground and do not produce the surface disruption typical of strip mines. Although there is some evidence of reclamation of mined land for use as parks, China does not require extensive reclamation and is creating significant acreages of abandoned mined land which is unsuitable for agriculture or other human uses, and inhospitable to indigenous wildlife. Chinese underground mines often experience severe surface subsidence (6-12 meters), negatively impacting farmland because it no longer drains well. China uses some subsidence areas for aquaculture ponds but has more than they need for that purpose. Reclamation of subsided ground is a significant problem in China.
Because most Chinese coal is for domestic consumption and is burned with little or no air pollution control equipment, it contributes greatly to visible smoke and severe air pollution in industrial areas using coal for fuel. Air pollution control equipment is being installed on some plants, but there are unconfirmed reports it is only turned on when inspectors visit. China's carbon dioxide emissions may increase 30% in 2008 due to increased coal combustion.[citation needed]
geologic conditions
Equipment to be used depends on geologic conditions. For example, to remove overburden that is loose or unconsolidated, a bucket wheel excavator might be the most productive. The life of some area mines may be more than 50 years. [7]
[edit] Contour mining
Contour mining
The contour mining method consists of removing overburden from the seam in a pattern following the contours along a ridge or around a hillside. This method is most commonly used in areas with rolling to steep terrain. It was once common to deposit the spoil on the downslope side of the bench thus created, but this method of spoil disposal consumed much additional land and created severe landslide and erosion problems. To alleviate these problems, a variety of methods were devised to use freshly cut overburden to refill mined-out areas. These haul-back or lateral movement methods generally consist of an initial cut with the spoil deposited downslope or at some other site and spoil from the second cut refilling the first. A ridge of undisturbed natural material 15 to 20 feet (6.1 m) wide is often intentionally left at the outer edge of the mined area. This barrier adds stability to the reclaimed slope by preventing spoil from slumping or sliding downhill.[8]
[edit] Contour mining
Contour mining
The contour mining method consists of removing overburden from the seam in a pattern following the contours along a ridge or around a hillside. This method is most commonly used in areas with rolling to steep terrain. It was once common to deposit the spoil on the downslope side of the bench thus created, but this method of spoil disposal consumed much additional land and created severe landslide and erosion problems. To alleviate these problems, a variety of methods were devised to use freshly cut overburden to refill mined-out areas. These haul-back or lateral movement methods generally consist of an initial cut with the spoil deposited downslope or at some other site and spoil from the second cut refilling the first. A ridge of undisturbed natural material 15 to 20 feet (6.1 m) wide is often intentionally left at the outer edge of the mined area. This barrier adds stability to the reclaimed slope by preventing spoil from slumping or sliding downhill.[8]
Strip mining
Strip mining exposes the coal by removing the overburden (the earth above the coal seam(s)) in long cuts or strips. The spoil from the first strip is deposited in an area outside the planned mining area. Spoil from subsequent cuts is deposited as fill in the previous cut after coal has been removed. Usually, the process is to drill the strip of overburden next to the previously mined strip. The drill holes are filled with explosives and blasted. The overburden is then removed using large earthmoving equipment such as draglines, shovel and trucks, excavator and trucks, or bucket-wheels and conveyors. This overburden is put into the previously mined (and now empty) strip. When all the overburden is removed, the underlying coal seam will be exposed (a 'block' of coal). This block of coal may be drilled and blasted (if hard) or otherwise loaded onto trucks or conveyors for transport to the coal preparation (or wash) plant. Once this strip is empty of coal, the process is repeated with a new strip being created next to it. This method is most suitable for areas with flat terrain.
Area mining
In this mining method, explosives are first use in order to break through the surface of the mining area. The coal is then removed by draglines or by shovel and truck. Once the coal seam is exposed, it is drilled, fractured and thoroughly mined in strips. The coal is then loaded on to large trucks or conveyors for transport to either the coal preparation plant or direct to where it will be used[5].
Most open cast mines in the United States extract bituminous coal. In Australia and South Africa open cast mining is used for both thermal and metallurgical coals. In South Wales open casting for steam coal and anthracite is practiced. Surface mining accounts for around 80% of pr
Area mining
Most open cast mines in the United States extract bituminous coal. In Australia and South Africa open cast mining is used for both thermal and metallurgical coals. In South Wales open casting for steam coal and anthracite is practiced. Surface mining accounts for around 80% of pr
Area mining
colambia mines
When coal seams are near the surface, it may be economical to extract the coal using open cut (also referred to as open cast, open pit, or strip) mining methods. Open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited. Large Open Cast mines can cover an area of many square kilometers and use very large pieces of equipment. This equipment can include the following: Draglines which operate by removing the overburden, power shovels, large trucks in which transport overburden and coal, bucket wheel excavators, and conveyors.
Surface mining
Surface mining and deep underground mining are the two basic methods of mining. The choice of mining method depends primarily on depth of burial and thickness of the coal seam. Seams relatively close to the surface, at depths less than approximately 180 feet (55 m), are usually surface mined. Coals that occur at depths of 180 to 300 feet (91 m) are usually deep mined but, in some cases, surface mining techniques can be used. For example, some western U.S. coals that occur at depths in excess of 200 feet (61 m) are mined by open pit methods, due to thickness of the seam (60-90 feet). Coals occurring below 300 feet (91 m) are usually deep mined.[4]
Modern surface mining
Modern surface mining
metod of coal
The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, and also the geology and environmental factors of the area being mined. Coal mining processes are generally differentiated by whether they operate on the surface or underground. Many coals extracted from both surface and underground mines require washing in a coal preparation plant.
Coal is mined only where mining is technically feasible and economically justifiable. Technical and economic feasibility are evaluated on several factors: regional geologic conditions; overburden characteristics; coal seam continuity, thickness, structure, quality, and depth; strength of materials above and below the seam for roof and floor conditions; topography (especially altitude and slope); climate; land ownership as it affects the availability of land for mining and access; surface drainage patterns; ground water conditions; availability of labor and materials; coal purchaser requirements in terms of tonnage, quality, and destination; and capital investment requirements.
Coal is mined only where mining is technically feasible and economically justifiable. Technical and economic feasibility are evaluated on several factors: regional geologic conditions; overburden characteristics; coal seam continuity, thickness, structure, quality, and depth; strength of materials above and below the seam for roof and floor conditions; topography (especially altitude and slope); climate; land ownership as it affects the availability of land for mining and access; surface drainage patterns; ground water conditions; availability of labor and materials; coal purchaser requirements in terms of tonnage, quality, and destination; and capital investment requirements.
coal mine
Coal mining is the extraction or removal of coal from the earth by mining. When coal is used for fuel in power generation it is referred to as steaming or thermal coal. Coal that is used to create coke for steel manufacturing is referred to as coking or metallurgical coal.[1] Coal is also an important source of Methanol which resides in binding resin, plywood, and acetic acid, plastic bottles. Coal is the means of producing more than half of the United States of America's electricity.[2]. In the United States, United Kingdom, and South Africa, a coal mine and its accompanying structures are collectively known as a colliery. In Australia, 'colliery' usually only refers to an underground coal mine. Methods of extraction
Tuesday, October 27, 2009
coal shortage
The impact of the coal shortage is already being felt. There have been record power shortfalls in Shanxi Province, where the government had to ration power supplies, hurting energy-intensive plants such as aluminium smelters. China's top 20 aluminium smelters, including Aluminium Corp of China Ltd (Chalco), will cut production by up to 10% to reduce power consumption. Other industrial provinces, such as Shandong in the north and Guangdong in the south, have forecast deep power deficits. “Beijing froze the price miners are paid for thermal coal until the end of the year as it seeks to cap power prices.” Henan, another big aluminium producing province and one of the nation's most popular, has started to restrict power to industrial users in eight regions and cities, while Shanxi province on Thursday said it had begun to ration power supplies as power plants ran short of coal. Some of the power shortfall can be met by diesel generators, and in fact during the last major power crisis in 2004 China's diesel demand surged by 15%, helping oil prices' first ascent above $50 a barrel. The ultimate solution, though, would be to allow markets to set power tariffs, but Beijing would be reluctant to make such a move when inflation is already near a 12-year high. "If the power tariff is opened up, all problems will be solved but its possible impact on the economy is still in question," said Lin of Xiamen University. ($1=6.860 Yuan). |   Expand Image Miners understand if they don't dig out all the coal now, they can sell later for a better price. |
 Expand Image Chinese producer prices for coal and power since the start of 2007. |
china small coal
China has failed to meet demand to reopen thousands small coal mines, which has worsened the country’s current power shortage. Also, local officials still fear Beijing's wrath if they suffer more high-profile disasters.
Weeks after the central government urged miners to reopen the mines, effectively reversing a years-old policy of shutting them in order to improve safety in the world's deadliest coal industry, local officials are proving reluctant. And Beijing's freeze on coal prices has lowered the incentive for miners.
failure to boost domestic coal supplies spells trouble for coal-fired electricity generators who produce four fifths of China's power, and could add to this summer's emerging power crisis, which has already forced aluminium smelters to cut output by up to a tenth and could stoke demand for oil.
"Local government officials are more concerned about personal interest. They are afraid of the punishment a mine accident could bring to them," said Li Chaolin, a coal analyst at an industry body based in Beijing.
“China's small coal mines are eight times more deadly per ton of coal than larger mines.”
They are right to be concerned. Six government officials in the Luliang region of Shanxi were sacked after a blast at a small mine, approved to re-open just a month earlier, killed 34 in June, the state-run Xinhua news agency reported.
China has been pushing forward a safety campaign for three years, shutting down the kind of small, inefficient and often dangerous mines that provided 38% of its coal last year.
Around 90% of China's coal mines are classified as small, but they are eight times more deadly per ton of coal produced than the larger mines.
From 1995 to early 2008, the number of coal mines in China had fallen around 80% to about 16,000. Over the same period the death toll is down 40% to 3,786 in 2007, according to the State Administration of Coal Mine Safety.
Beijing's goal is to reduce the number of small mines to under 10,000 by 2010, and to eliminate them by 2015.
But in late May, when coal stocks in the country's key power plants had fallen to critical levels and summer power shortages loomed, China's premier Wen Jiabao called for an increase in coal output, while the country's cabinet asked local governments to speed up approvals for restarting small coal mines.
Some have returned to production in Shanxi, China's top coal producing province, but many are still closed or performing maintenance, traders and analysts said.
And in late June, the Shanxi provincial government ordered local governments to shut down illegal coal mines, highlighting the conflicting signals that have kept officials cautious.
"How can local officials re-open small mines? They want to keep their jobs," said a trader based in Shanxi, who declined to be named.
Diamonds in China
Diamonds in China
China Diamond Corp., reported a 108 percent increase in production results from the 701 Changma Diamond Mine located in Shandong Province, China. China Diamond is headquartered in London, Ontario, Canada, and is engaged in mining for diamonds and the exploration and advancement of diamond and gold prospects in China.
The 701 Changma Diamond Mine is the company’s principal mining operation the company said in a press release on July 14. Total carats produced from January through March 2005 were 9,240.50, but from April through June total carats produced hit 19,221.20.
Operations were carried out in a higher grade area of the deposit, namely the Small Pipe, which returned an average monthly grade of 1.23 carats per ton. This area is expected to continue to be in production well into August 2005.
china coal
A gas explosion at a coal mine in China's central Henan province early on Tuesday killed 35 people and 44 others were missing, the
government's work safety watchdog said.
Another 14 workers had escaped the mine, which was a small, locally operated venture, at the time of the accident, the State Administration of Work Safety said in a statement on its website (www.chinasafety.gov.cn).
The report said rescue teams were still searching for the missing miners and safety officials would investigate the cause of the blast, but it gave no further details.
The official Xinhua news agency said the pit was being upgraded, and the local government had not given permission to resume production there.
Lax safety standards and strong demand for resources have made China's mines the deadliest in the world, despite a government drive to clamp down on the tiny, unsafe operations that are the site of most accidents.
More than 3,000 people died in mine floods, explosions, collapses and other accidents in 2008 alone.
Another 14 workers had escaped the mine, which was a small, locally operated venture, at the time of the accident, the State Administration of Work Safety said in a statement on its website (www.chinasafety.gov.cn).
The report said rescue teams were still searching for the missing miners and safety officials would investigate the cause of the blast, but it gave no further details.
The official Xinhua news agency said the pit was being upgraded, and the local government had not given permission to resume production there.
Lax safety standards and strong demand for resources have made China's mines the deadliest in the world, despite a government drive to clamp down on the tiny, unsafe operations that are the site of most accidents.
More than 3,000 people died in mine floods, explosions, collapses and other accidents in 2008 alone.
Thursday, October 15, 2009
History
History
Please help improve this article by expanding it. Further information might be found on the talk page. (October 2008)
Main article: History of coal mining
The oldest continuously worked deep-mine in the United Kingdom and possibly in the world is Tower Colliery in South Wales valleys in the heart of the South Wales coalfield. This colliery was first developed in 1805, and its miners bought it out at the end of the 20th century, to prevent it from being closed. Tower Colliery was finally closed on January 25, 2008, although production continues at the Aberpergwym drift mine nearby.
Coal was mined in colonial America in the early 1700s, and commercial mining first occurred around 1730 in Midlothian, Virginia.[3]
Coal-cutting machines were invented in the 1880s. Before the invention, coal was mined from underground with a pick and shovel.
By 1912, surface mining was conducted with steam shovels designed for coal mining.
Please help improve this article by expanding it. Further information might be found on the talk page. (October 2008)
Main article: History of coal mining
The oldest continuously worked deep-mine in the United Kingdom and possibly in the world is Tower Colliery in South Wales valleys in the heart of the South Wales coalfield. This colliery was first developed in 1805, and its miners bought it out at the end of the 20th century, to prevent it from being closed. Tower Colliery was finally closed on January 25, 2008, although production continues at the Aberpergwym drift mine nearby.
Coal was mined in colonial America in the early 1700s, and commercial mining first occurred around 1730 in Midlothian, Virginia.[3]
Coal-cutting machines were invented in the 1880s. Before the invention, coal was mined from underground with a pick and shovel.
By 1912, surface mining was conducted with steam shovels designed for coal mining.
Major coal producers
Major coal producers
The reserve life is an estimate based only on current production levels for the countries shown, and makes no assumptions of future production or even current production trends.
Production of Coal by Country and year (million tonnes)[55]
Country
2003
2004
2005
2006
Share
Reserve Life (years)
China
1722.0
1992.3
2204.7
2380.0
38.4 %
48
USA
972.3
1008.9
1026.5
1053.6
17.0 %
234
India
375.4
407.7
428.4
447.3
7.2 %
207
Australia
351.5
366.1
378.8
373.8
6.0 %
210
Russia
276.7
281.7
298.5
309.2
5.0 %
508
South Africa
237.9
243.4
244.4
256.9
4.1 %
190
Germany
204.9
207.8
202.8
197.2
3.2 %
34
Indonesia
114.3
132.4
146.9
195.0
3.1 %
25
Poland
163.8
162.4
159.5
156.1
2.5 %
90
Total World
5187.6
5585.3
5886.7
6195.1
100 %
142
The reserve life is an estimate based only on current production levels for the countries shown, and makes no assumptions of future production or even current production trends.
Production of Coal by Country and year (million tonnes)[55]
Country
2003
2004
2005
2006
Share
Reserve Life (years)
China
1722.0
1992.3
2204.7
2380.0
38.4 %
48
USA
972.3
1008.9
1026.5
1053.6
17.0 %
234
India
375.4
407.7
428.4
447.3
7.2 %
207
Australia
351.5
366.1
378.8
373.8
6.0 %
210
Russia
276.7
281.7
298.5
309.2
5.0 %
508
South Africa
237.9
243.4
244.4
256.9
4.1 %
190
Germany
204.9
207.8
202.8
197.2
3.2 %
34
Indonesia
114.3
132.4
146.9
195.0
3.1 %
25
Poland
163.8
162.4
159.5
156.1
2.5 %
90
Total World
5187.6
5585.3
5886.7
6195.1
100 %
142
Production trends
Production trends
Coal output in 2005
A coal mine in Wyoming, United States. The United States has the world's largest coal reserves.
In 2006, China was the top producer of coal with 38% share followed by the USA and India, reports the British Geological Survey.
World coal reserves
At the end of 2006 the recoverable coal reserves amounted around 800 or 900 gigatons. The United States Energy Information Administration gives world reserves as 930 billion short tons[50] (equal to 843 gigatons) as of 2006. At the current extraction rate, this would last 132 years.[51] However, the rate of coal consumption is annually increasing at 2-3% per year and, setting the growth rate to 2.5% yields an exponential depletion time of 56 years (in 2065).[52] At the current global total energy consumption of 15.7 terawatts,[53] there is enough coal to provide the entire planet with all of its energy for 37 years (assuming 0% growth in demand and ignoring transportation's need for liquid fuels).[original research?]
The 930 billion short tons of recoverable coal reserves estimated by the Energy Information Administration are equal to about 4,116 BBOE (billion barrels of oil equivalent).[citation needed] The amount of coal burned during 2007 was estimated at 7.075 billion short tons, or 133.179 quadrillion BTU's.[54] In terms of heat content, this is about 57 million barrels of oil equivalent per day. By comparison in 2007, natural gas provided 51 million barrels of oil equivalent per day, while oil provided 85.8 million barrels per day.
British Petroleum, in its annual report 2007, estimated at 2006 end, there were 909,064 million tons of proven coal reserves worldwide, or 147 years reserves-to-production ratio. This figure only includes reserves classified as "proven"; exploration drilling programs by mining companies, particularly in under-explored areas, are continually providing new reserves. In many cases, companies are aware of coal deposits that have not been sufficiently drilled to qualify as "proven". However, some nations haven't updated their information and assume reserves remain at the same levels even with withdrawals.
Coal output in 2005
A coal mine in Wyoming, United States. The United States has the world's largest coal reserves.
In 2006, China was the top producer of coal with 38% share followed by the USA and India, reports the British Geological Survey.
World coal reserves
At the end of 2006 the recoverable coal reserves amounted around 800 or 900 gigatons. The United States Energy Information Administration gives world reserves as 930 billion short tons[50] (equal to 843 gigatons) as of 2006. At the current extraction rate, this would last 132 years.[51] However, the rate of coal consumption is annually increasing at 2-3% per year and, setting the growth rate to 2.5% yields an exponential depletion time of 56 years (in 2065).[52] At the current global total energy consumption of 15.7 terawatts,[53] there is enough coal to provide the entire planet with all of its energy for 37 years (assuming 0% growth in demand and ignoring transportation's need for liquid fuels).[original research?]
The 930 billion short tons of recoverable coal reserves estimated by the Energy Information Administration are equal to about 4,116 BBOE (billion barrels of oil equivalent).[citation needed] The amount of coal burned during 2007 was estimated at 7.075 billion short tons, or 133.179 quadrillion BTU's.[54] In terms of heat content, this is about 57 million barrels of oil equivalent per day. By comparison in 2007, natural gas provided 51 million barrels of oil equivalent per day, while oil provided 85.8 million barrels per day.
British Petroleum, in its annual report 2007, estimated at 2006 end, there were 909,064 million tons of proven coal reserves worldwide, or 147 years reserves-to-production ratio. This figure only includes reserves classified as "proven"; exploration drilling programs by mining companies, particularly in under-explored areas, are continually providing new reserves. In many cases, companies are aware of coal deposits that have not been sufficiently drilled to qualify as "proven". However, some nations haven't updated their information and assume reserves remain at the same levels even with withdrawals.
Underground fires
Underground fires
Main article: Coal seam fire
Most underground fires are caused by the mineral marcasite.[citation needed] chemical formula FeS2, it is chemically, the same as pyrite (fool's gold) but structurally complex. Marcasite and pyrite very commonly occur in association with coal beds. these minerals form the source of the sulphur which occurs within the coal. Marcasite is highly unstable at pressures and temperatures close to the earths surface. due to its unstable nature, it may react spontaneously, consuming itself and releasing heat. In the event that sufficient heat is generated and coal occurs close by, the coal may be set alight underground and such a blaze may go on burning for tens to hundreds of years.
There are hundreds of coal fires burning around the world.[41] Those burning underground can be difficult to locate and many cannot be extinguished. Fires can cause the ground above to subside, their combustion gases are dangerous to life, and breaking out to the surface can initiate surface wildfires. Coal seams can be set on fire by spontaneous combustion or contact with a mine fire or surface fire. A grass fire in a coal area can set dozens of coal seams on fire.[42][43] Coal fires in China burn 109 million tons of coal a year, emitting 360 million metric tons of CO2. This contradicts the ratio of 1:1.83 given earlier, but it amounts to 2-3% of the annual worldwide production of CO2 from fossil fuels, or as much as emitted from all of the cars and light trucks in the United States.[44][45] In Centralia, Pennsylvania (a borough located in the Coal Region of the United States) an exposed vein of coal ignited in 1962 due to a trash fire in the borough landfill, located in an abandoned anthracite strip mine pit. Attempts to extinguish the fire were unsuccessful, and it continues to burn underground to this day. The Australian Burning Mountain was originally believed to be a volcano, but the smoke and ash comes from a coal fire which may have been burning for over 5,500 years.[46]
At Kuh i Malik in Yagnob Valley, Tajikistan, coal deposits have been burning for thousands of years, creating vast underground labyrinths full of unique minerals, some of them very beautiful. Local people once used this method to mine ammoniac. This place has been well-known since the time of Herodotus, but European geographers misinterpreted the Ancient Greek descriptions as the evidence of active volcanism in Turkestan (up to the 19th century, when the Russian army invaded the area).
The reddish siltstone rock that caps many ridges and buttes in the Powder River Basin (Wyoming), and in western North Dakota is called porcelanite, which also may resemble the coal burning waste "clinker" or volcanic "scoria".[47] Clinker is rock that has been fused by the natural burning of coal. In the Powder River Basin approximately 27 to 54 billion tons of coal burned within the past three million years.[48] Wild coal fires in the area were reported by the Lewis and Clark Expedition as well as explorers and settlers in the area.[49]
Main article: Coal seam fire
Most underground fires are caused by the mineral marcasite.[citation needed] chemical formula FeS2, it is chemically, the same as pyrite (fool's gold) but structurally complex. Marcasite and pyrite very commonly occur in association with coal beds. these minerals form the source of the sulphur which occurs within the coal. Marcasite is highly unstable at pressures and temperatures close to the earths surface. due to its unstable nature, it may react spontaneously, consuming itself and releasing heat. In the event that sufficient heat is generated and coal occurs close by, the coal may be set alight underground and such a blaze may go on burning for tens to hundreds of years.
There are hundreds of coal fires burning around the world.[41] Those burning underground can be difficult to locate and many cannot be extinguished. Fires can cause the ground above to subside, their combustion gases are dangerous to life, and breaking out to the surface can initiate surface wildfires. Coal seams can be set on fire by spontaneous combustion or contact with a mine fire or surface fire. A grass fire in a coal area can set dozens of coal seams on fire.[42][43] Coal fires in China burn 109 million tons of coal a year, emitting 360 million metric tons of CO2. This contradicts the ratio of 1:1.83 given earlier, but it amounts to 2-3% of the annual worldwide production of CO2 from fossil fuels, or as much as emitted from all of the cars and light trucks in the United States.[44][45] In Centralia, Pennsylvania (a borough located in the Coal Region of the United States) an exposed vein of coal ignited in 1962 due to a trash fire in the borough landfill, located in an abandoned anthracite strip mine pit. Attempts to extinguish the fire were unsuccessful, and it continues to burn underground to this day. The Australian Burning Mountain was originally believed to be a volcano, but the smoke and ash comes from a coal fire which may have been burning for over 5,500 years.[46]
At Kuh i Malik in Yagnob Valley, Tajikistan, coal deposits have been burning for thousands of years, creating vast underground labyrinths full of unique minerals, some of them very beautiful. Local people once used this method to mine ammoniac. This place has been well-known since the time of Herodotus, but European geographers misinterpreted the Ancient Greek descriptions as the evidence of active volcanism in Turkestan (up to the 19th century, when the Russian army invaded the area).
The reddish siltstone rock that caps many ridges and buttes in the Powder River Basin (Wyoming), and in western North Dakota is called porcelanite, which also may resemble the coal burning waste "clinker" or volcanic "scoria".[47] Clinker is rock that has been fused by the natural burning of coal. In the Powder River Basin approximately 27 to 54 billion tons of coal burned within the past three million years.[48] Wild coal fires in the area were reported by the Lewis and Clark Expedition as well as explorers and settlers in the area.[49]
Energy density
] Energy density
Main article: Energy value of coal
The energy density of coal, i.e. its heating value, is roughly 24 megajoules per kilogram.[38]
The energy density of coal can also be expressed in kilowatt-hours for some unit of mass, the units that electricity is most commonly sold in, to estimate how much coal is required to power electrical appliances. One kilowatt-hour is 3.6 MJ, so the energy density of coal is 6.67 kW·h/kg. The typical thermodynamic efficiency of coal power plants is about 30%, so of the 6.67 kW·h of energy per kilogram of coal, 30% of that—2.0 kW·h/kg—can successfully be turned into electricity; the rest is waste heat. So coal power plants obtain approximately 2.0 kW·h per kilogram of burned coal.
As an example, running one 100 watt lightbulb for one year requires 876 kW·h (100 W × 24 h/day × 365 {days in a year} = 876000 W·h = 876 kW·h). Converting this power usage into physical coal consumption:
It takes 438 kg (966 lb) of coal to power a computer for one full year.[39] One should also take into account transmission and distribution losses caused by resistance and heating in the power lines, which is in the order of 5–10%, depending on distance from the power station and other factors.
Main article: Energy value of coal
The energy density of coal, i.e. its heating value, is roughly 24 megajoules per kilogram.[38]
The energy density of coal can also be expressed in kilowatt-hours for some unit of mass, the units that electricity is most commonly sold in, to estimate how much coal is required to power electrical appliances. One kilowatt-hour is 3.6 MJ, so the energy density of coal is 6.67 kW·h/kg. The typical thermodynamic efficiency of coal power plants is about 30%, so of the 6.67 kW·h of energy per kilogram of coal, 30% of that—2.0 kW·h/kg—can successfully be turned into electricity; the rest is waste heat. So coal power plants obtain approximately 2.0 kW·h per kilogram of burned coal.
As an example, running one 100 watt lightbulb for one year requires 876 kW·h (100 W × 24 h/day × 365 {days in a year} = 876000 W·h = 876 kW·h). Converting this power usage into physical coal consumption:
It takes 438 kg (966 lb) of coal to power a computer for one full year.[39] One should also take into account transmission and distribution losses caused by resistance and heating in the power lines, which is in the order of 5–10%, depending on distance from the power station and other factors.
Environmental
Environmental effects
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
Economic aspects
Environmental effects
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
] Economic aspects] Environmental effects
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
[Economic aspects
Environmental effects
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
Economic aspects
Environmental effects
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
] Economic aspects] Environmental effects
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
[Economic aspects
Environmental effects
Main article: Environmental effects of coal
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event
There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.[32]
Generation of hundred of millions of tons of waste products, including fly ash, bottom ash, flue gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals
Acid rain from high sulfur coal
Interference with groundwater and water table levels
Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
Impact of water use on flows of rivers and consequential impact on other land-uses
Dust nuisance
Subsidence above tunnels, sometimes damaging infrastructure[citation needed]
Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
Coal-fired power plants shorten nearly 24,000 lives a year in the United States, including 2,800 from lung cancer.[33]
Coal-fired power plant releases emissions including mercury, selenium, and arsenic which are harmful to human health and the environment.[34]
Gasification
[Gasification
Main articles: Coal gasification and Underground coal gasification
Coal gasification can be used to produce syngas, a mixture of carbon monoxide (CO) and hydrogen (H2) gas. This syngas can then be converted into transportation fuels like gasoline and diesel through the Fischer-Tropsch process. Currently, this technology is being used by the Sasol chemical company of South Africa to make gasoline from coal and natural gas. Alternatively, the hydrogen obtained from gasification can be used for various purposes such as powering a hydrogen economy, making ammonia, or upgrading fossil fuels.
During gasification, the coal is mixed with oxygen and steam (water vapor) while also being heated and pressurized. During the reaction, oxygen and water molecules oxidize the coal into carbon monoxide (CO) while also releasing hydrogen (H2) gas. This process has been conducted in both underground coal mines and in coal refineries.
(Coal) + O2 + H2O → H2 + CO
If the refiner wants to produce gasoline, the syngas is collected at this state and routed into a Fischer-Tropsch reaction. If hydrogen is the desired end-product, however, the syngas is fed into the water gas shift reaction where more hydrogen is liberated.
CO + H2O → CO2 + H2
High prices of oil and natural gas are leading to increased interest in "BTU Conversion" technologies such as gasification, methanation and liquefaction. The Synthetic Fuels Corporation was a U.S. government-funded corporation established in 1980 to create a market for alternatives to imported fossil fuels (such as coal gasification). The corporation was discontinued in 1985.
In the past, coal was converted to make coal gas, which was piped to customers to burn for illumination, heating, and cooking. At present, the safer natural gas is used instead.
Main articles: Coal gasification and Underground coal gasification
Coal gasification can be used to produce syngas, a mixture of carbon monoxide (CO) and hydrogen (H2) gas. This syngas can then be converted into transportation fuels like gasoline and diesel through the Fischer-Tropsch process. Currently, this technology is being used by the Sasol chemical company of South Africa to make gasoline from coal and natural gas. Alternatively, the hydrogen obtained from gasification can be used for various purposes such as powering a hydrogen economy, making ammonia, or upgrading fossil fuels.
During gasification, the coal is mixed with oxygen and steam (water vapor) while also being heated and pressurized. During the reaction, oxygen and water molecules oxidize the coal into carbon monoxide (CO) while also releasing hydrogen (H2) gas. This process has been conducted in both underground coal mines and in coal refineries.
(Coal) + O2 + H2O → H2 + CO
If the refiner wants to produce gasoline, the syngas is collected at this state and routed into a Fischer-Tropsch reaction. If hydrogen is the desired end-product, however, the syngas is fed into the water gas shift reaction where more hydrogen is liberated.
CO + H2O → CO2 + H2
High prices of oil and natural gas are leading to increased interest in "BTU Conversion" technologies such as gasification, methanation and liquefaction. The Synthetic Fuels Corporation was a U.S. government-funded corporation established in 1980 to create a market for alternatives to imported fossil fuels (such as coal gasification). The corporation was discontinued in 1985.
In the past, coal was converted to make coal gas, which was piped to customers to burn for illumination, heating, and cooking. At present, the safer natural gas is used instead.
Ethanol production
Ethanol production
The reaction of coal and natural gas was used by a German manufacturer for Buna rubber: Chemische Werke Huls, at Marl, Germany, and AVCO Corp in the US. Consequently several references had described both Huls Arc Process and AVCO rotating arc reactor.[18][19] Both reactors are of cylindrical shape and have a rotating electric arc. The cathode is at the cylinder axis, while the anode is on the circumference. As methane gas provided the highest yield, then it is forced with coal powder into a vortex passing through the electric arc for few milliseconds.
Huls Arc Process[20] produced a mixture of acetylene and ethylene gases. The reaction conditions can be varied to determine the needed product. Increasing the Specific Energy Requirement (SER) favor acetylene production, and lower SER is for ethylene:
Enthalpy Change for Ethylene:[21] = 127.34 kJ/mol, while for acetylene: = 301.4 kJ/mol. As a consequence, recent production processes are using conventional heating instead of electric arc.
Hydration of ethylene gas producing ethanol is the most important process for ethanol production. Vapor phase process is the preferred one[22] in which ethylene and steam pass over a catalyst. One of the most accepted catalyst is diatomite impregnated with phosphoric acid.
The reaction of coal and natural gas was used by a German manufacturer for Buna rubber: Chemische Werke Huls, at Marl, Germany, and AVCO Corp in the US. Consequently several references had described both Huls Arc Process and AVCO rotating arc reactor.[18][19] Both reactors are of cylindrical shape and have a rotating electric arc. The cathode is at the cylinder axis, while the anode is on the circumference. As methane gas provided the highest yield, then it is forced with coal powder into a vortex passing through the electric arc for few milliseconds.
Huls Arc Process[20] produced a mixture of acetylene and ethylene gases. The reaction conditions can be varied to determine the needed product. Increasing the Specific Energy Requirement (SER) favor acetylene production, and lower SER is for ethylene:
Enthalpy Change for Ethylene:[21] = 127.34 kJ/mol, while for acetylene: = 301.4 kJ/mol. As a consequence, recent production processes are using conventional heating instead of electric arc.
Hydration of ethylene gas producing ethanol is the most important process for ethanol production. Vapor phase process is the preferred one[22] in which ethylene and steam pass over a catalyst. One of the most accepted catalyst is diatomite impregnated with phosphoric acid.
cooking
Coking and use of coke
Main article: Coke (fuel)
Coke oven at smokeless fuel plant, South Wales
Coke is a solid carbonaceous residue derived from low-ash, low-sulfur bituminous coal from which the volatile constituents are driven off by baking in an oven without oxygen at temperatures as high as 1,000 °C (1,832 °F) so that the fixed carbon and residual ash are fused together. Metallurgical coke is used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. The product is too rich in dissolved carbon, and must be treated further to make steel. The coke must be strong enough to resist the weight of overburden in the blast furnace, which is why coking coal is so important in making steel by the conventional route. However, the alternative route to is direct reduced iron, where any carbonaceous fuel can be used to make sponge or pelletised iron. Coke from coal is grey, hard, and porous and has a heating value of 24.8 million Btu/ton (29.6 MJ/kg). Some cokemaking processes produce valuable by-products that include coal tar, ammonia, light oils, and "coal gas".
Petroleum coke is the solid residue obtained in oil refining, which resembles coke but contains too many impurities to be useful in metallurgical applications
Main article: Coke (fuel)
Coke oven at smokeless fuel plant, South Wales
Coke is a solid carbonaceous residue derived from low-ash, low-sulfur bituminous coal from which the volatile constituents are driven off by baking in an oven without oxygen at temperatures as high as 1,000 °C (1,832 °F) so that the fixed carbon and residual ash are fused together. Metallurgical coke is used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. The product is too rich in dissolved carbon, and must be treated further to make steel. The coke must be strong enough to resist the weight of overburden in the blast furnace, which is why coking coal is so important in making steel by the conventional route. However, the alternative route to is direct reduced iron, where any carbonaceous fuel can be used to make sponge or pelletised iron. Coke from coal is grey, hard, and porous and has a heating value of 24.8 million Btu/ton (29.6 MJ/kg). Some cokemaking processes produce valuable by-products that include coal tar, ammonia, light oils, and "coal gas".
Petroleum coke is the solid residue obtained in oil refining, which resembles coke but contains too many impurities to be useful in metallurgical applications
coal of use
[edit] Coal as fuel
Further information: Electricity generation, Clean coal technology, Coal electricity, and Global warming
Coal is primarily used as a solid fuel to produce electricity and heat through combustion. World coal consumption was about 6,743,786,000 short tons in 2006[10] and is expected to increase 48% to 9.98 billion short tons by 2030.[11] China produced 2.38 billion tons in 2006. India produced about 447.3 million tons in 2006. 68.7% of China's electricity comes from coal. The USA consumes about 14% of the world total, using 90% of it for generation of electricity.[12]
When coal is used for electricity generation, it 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 and create electricity. The thermodynamic efficiency of this process has been improved over time. "Standard" steam turbines have topped out with some of the most advanced reaching about 35% thermodynamic efficiency for the entire process, although newer combined cycle plants can reach efficiencies as high as 58%. Increasing the combustion temperature can boost this efficiency even further.[13] Old coal power plants, especially "grandfathered" plants, are significantly less efficient and produce higher levels of waste heat. About 40% of the world's electricity comes from coal,[14] and approximately 49% of the United States electricity comes from coal.[15]
Fuels for heating
Heating oilWood pelletKerosenePropaneNatural gasElectricityWoodCoal
The emergence of the supercritical turbine concept envisions running a boiler at extremely high temperatures and pressures with projected efficiencies of 46%, with further theorized increases in temperature and pressure perhaps resulting in even higher efficiencies.[16]
Other efficient ways to use coal are combined cycle power plants, combined heat and power cogeneration, and an MHD topping cycle.
Approximately 40% of the world electricity production uses coal. The total known deposits recoverable by current technologies, including highly polluting, low energy content types of coal (i.e., lignite, bituminous), is sufficient for many years. However, consumption is increasing and maximal production could be reached within decades (see World Coal Reserves, below).
A more energy-efficient way of using coal for electricity production would be via solid-oxide fuel cells or molten-carbonate fuel cells (or any oxygen ion transport based fuel cells that do not discriminate between fuels, as long as they consume oxygen), which would be able to get 60%–85% combined efficiency (direct electricity + waste heat steam turbine).[citation needed] Currently these fuel cell technologies can only process gaseous fuels, and they are also sensitive to sulfur poisoning, issues which would first have to be worked out before large scale commercial success is possible with coal. As far as gaseous fuels go, one idea is pulverized coal in a gas carrier, such as nitrogen. Another option is coal gasification with water, which may lower fuel cell voltage by introducing oxygen to the fuel side of the electrolyte, but may also greatly simplify carbon sequestration. However, this technology has been criticised as being inefficient, slow, risky and costly, while doing nothing about total emissions from mining, processing and combustion.[17] Another efficient and clean
Further information: Electricity generation, Clean coal technology, Coal electricity, and Global warming
Coal is primarily used as a solid fuel to produce electricity and heat through combustion. World coal consumption was about 6,743,786,000 short tons in 2006[10] and is expected to increase 48% to 9.98 billion short tons by 2030.[11] China produced 2.38 billion tons in 2006. India produced about 447.3 million tons in 2006. 68.7% of China's electricity comes from coal. The USA consumes about 14% of the world total, using 90% of it for generation of electricity.[12]
When coal is used for electricity generation, it 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 and create electricity. The thermodynamic efficiency of this process has been improved over time. "Standard" steam turbines have topped out with some of the most advanced reaching about 35% thermodynamic efficiency for the entire process, although newer combined cycle plants can reach efficiencies as high as 58%. Increasing the combustion temperature can boost this efficiency even further.[13] Old coal power plants, especially "grandfathered" plants, are significantly less efficient and produce higher levels of waste heat. About 40% of the world's electricity comes from coal,[14] and approximately 49% of the United States electricity comes from coal.[15]
Fuels for heating
Heating oilWood pelletKerosenePropaneNatural gasElectricityWoodCoal
The emergence of the supercritical turbine concept envisions running a boiler at extremely high temperatures and pressures with projected efficiencies of 46%, with further theorized increases in temperature and pressure perhaps resulting in even higher efficiencies.[16]
Other efficient ways to use coal are combined cycle power plants, combined heat and power cogeneration, and an MHD topping cycle.
Approximately 40% of the world electricity production uses coal. The total known deposits recoverable by current technologies, including highly polluting, low energy content types of coal (i.e., lignite, bituminous), is sufficient for many years. However, consumption is increasing and maximal production could be reached within decades (see World Coal Reserves, below).
A more energy-efficient way of using coal for electricity production would be via solid-oxide fuel cells or molten-carbonate fuel cells (or any oxygen ion transport based fuel cells that do not discriminate between fuels, as long as they consume oxygen), which would be able to get 60%–85% combined efficiency (direct electricity + waste heat steam turbine).[citation needed] Currently these fuel cell technologies can only process gaseous fuels, and they are also sensitive to sulfur poisoning, issues which would first have to be worked out before large scale commercial success is possible with coal. As far as gaseous fuels go, one idea is pulverized coal in a gas carrier, such as nitrogen. Another option is coal gasification with water, which may lower fuel cell voltage by introducing oxygen to the fuel side of the electrolyte, but may also greatly simplify carbon sequestration. However, this technology has been criticised as being inefficient, slow, risky and costly, while doing nothing about total emissions from mining, processing and combustion.[17] Another efficient and clean
type of coal
As geological processes apply pressure to dead biotic matter over time, under suitable conditions it is transformed successively into
Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions, for example, Ireland and Finland.
Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Iron Age.
Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal are used primarily as fuel for steam-electric power generation. Additionally, it is an important source of light aromatic hydrocarbons for the chemical synthesis industry.
Bituminous coal, dense mineral, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke.
Anthracite, the highest rank; a harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically altered bituminous coal and petrified oil, as from the deposits in Pennsylvania.
Graphite, technically the highest rank, but difficult to ignite and is not so commonly used as fuel: it is mostly used in pencils and, when powdered, as a lubricant.
The classification of coal is generally based on the content of volatiles. However, the exact classification varies between countries. According to the German classification, coal is classified as follows:[2]
Name
Volatiles %
C Carbon %
H Hydrogen %
O Oxygen %
S Sulfur %
Heat content kJ/kg
Braunkohle (Lignite)
45-65
60-75
6.0-5.8
34-17
0.5-3
<28470
Flammkohle (Flame coal)
40-45
75-82
6.0-5.8
>9.8
~1
<32870
Gasflammkohle (Gas flame coal)
35-40
82-85
5.8-5.6
9.8-7.3
~1
<33910
Gaskohle (Gas coal)
28-35
85-87.5
5.6-5.0
7.3-4.5
~1
<34960
Fettkohle (Fat coal)
19-28
87.5-89.5
5.0-4.5
4.5-3.2
~1
<35380
Esskohle (Forge coal)
14-19
89.5-90.5
4.5-4.0
3.2-2.8
~1
<35380
Magerkohle (Non baking coal)
10-14
90.5-91.5
4.0-3.75
2.8-3.5
~1
35380
Anthrazit (Anthracite)
7-12
>91.5
<3.75
<2.5
~1
<35300
Percent by weight
Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions, for example, Ireland and Finland.
Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Iron Age.
Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal are used primarily as fuel for steam-electric power generation. Additionally, it is an important source of light aromatic hydrocarbons for the chemical synthesis industry.
Bituminous coal, dense mineral, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke.
Anthracite, the highest rank; a harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically altered bituminous coal and petrified oil, as from the deposits in Pennsylvania.
Graphite, technically the highest rank, but difficult to ignite and is not so commonly used as fuel: it is mostly used in pencils and, when powdered, as a lubricant.
The classification of coal is generally based on the content of volatiles. However, the exact classification varies between countries. According to the German classification, coal is classified as follows:[2]
Name
Volatiles %
C Carbon %
H Hydrogen %
O Oxygen %
S Sulfur %
Heat content kJ/kg
Braunkohle (Lignite)
45-65
60-75
6.0-5.8
34-17
0.5-3
<28470
Flammkohle (Flame coal)
40-45
75-82
6.0-5.8
>9.8
~1
<32870
Gasflammkohle (Gas flame coal)
35-40
82-85
5.8-5.6
9.8-7.3
~1
<33910
Gaskohle (Gas coal)
28-35
85-87.5
5.6-5.0
7.3-4.5
~1
<34960
Fettkohle (Fat coal)
19-28
87.5-89.5
5.0-4.5
4.5-3.2
~1
<35380
Esskohle (Forge coal)
14-19
89.5-90.5
4.5-4.0
3.2-2.8
~1
<35380
Magerkohle (Non baking coal)
10-14
90.5-91.5
4.0-3.75
2.8-3.5
~1
35380
Anthrazit (Anthracite)
7-12
>91.5
<3.75
<2.5
~1
<35300
Percent by weight
Friday, August 28, 2009
coalmine
Coal India May Invest $1.5 Billion in Overseas Mines (Update1)
By Pratik Parija
Aug. 27 (Bloomberg) -- Coal India Ltd. may invest as much as $1.5 billion to acquire mines overseas to help overcome a shortage of the fuel as the country plans to almost double power generation capacity by 2012.
The state monopoly is seeking mines in Australia, South Africa, the U.S., Indonesia and Mozambique with an annual capacity of 10 million to 15 million metric tons, Chairman Partha S. Bhattacharyya told reporters in New Delhi today.
Companies including NTPC Ltd., Reliance Power Ltd. and Tata Power Co. plan to boost generation to meet demand in the world’s second fastest-growing major economy. Coal India estimates a shortage of about 228 million tons a year by March 2012.
“Power companies will be the greatest beneficiaries,” said Girish Solanki, an analyst with Angel Broking Ltd. “The perennial coal shortage problem will be alleviated to an extent once they acquire a mine. Also, it is a good time to scout as coal prices have fallen.”
Coal India secured two blocks in Mozambique that may hold a combined 1 billion metric tons of thermal coal, along with some coking coal, Bhattacharyya said in an interview June 4.
Demand for coal is estimated to reach 731 million tons a year by March 2012, J. Goel, chief general manager of sales and marketing at Coal India, said on Feb. 24. The company wants local mining approvals sped up to boost domestic output.
To contact the reporter on this story: Pratik Parija in New Delhi at
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