COAL -AN ENERGY RESOURCE

Contents 1.

Introduction ................................................................................................................... 3

2.

Origin of coal ................................................................................................................ 3

3.

Coalification .................................................................................................................. 4

4.

Constituents................................................................................................................... 6 4.1.

Minerals in Coal...................................................................................................... 6

4.2.

Macerals ................................................................................................................. 6

5.

Types ............................................................................................................................ 7

6.

Coal Rank ..................................................................................................................... 8

7.

Coal Reserves and Resources ........................................................................................ 9

8.

Coal Extraction/ Coal Mining: ..................................................................................... 10 8.1.

Coal Preparation ................................................................................................... 10

8.2.

Coal Transportation............................................................................................... 11

8.3.

Safety at Coal Mines ............................................................................................. 11

9.

Coal Uses .................................................................................................................... 11

10.

Coal and the Environment ........................................................................................ 12

10.1.

Coal Mining & the Environment ........................................................................ 12

10.1.1.

Land Disturbance ....................................................................................... 12

10.1.2.

Mine Subsidence ........................................................................................ 12

10.1.3.

Water Pollution .......................................................................................... 12

10.1.4.

Dust & Noise Pollution............................................................................... 13

10.1.5.

Rehabilitation ............................................................................................. 13

10.1.6.

Using Methane from Coal Mines ................................................................ 13

10.2.

Coal Use & the Environment ............................................................................. 14

10.2.1.

Technological Response ............................................................................. 14

10.2.2.

Reducing Particulate Emissions .................................................................. 14

10.2.3.

Coal Cleaning ............................................................................................. 14

10.2.4.

Electrostatic Precipitators & Fabric Filters .................................................. 15

10.2.5.

Preventing Acid Rain ................................................................................. 15

10.2.6.

Reducing Carbon Dioxide Emissions .......................................................... 16

10.2.7.

Combustion Efficiency ............................................................................... 16

10.2.8.

Carbon Capture & Storage .......................................................................... 17

10.2.9.

Coal & Renewable Energy ......................................................................... 18

10.2.10.

Overcoming Environmental Impacts ........................................................... 19

11.

World coal Activity .................................................................................................. 20

12.

Coal Reserves ........................................................................................................... 20 1

13.

Coal Production ........................................................................................................ 22

14.

Coal Consumption .................................................................................................... 24

15.

Coal Trade................................................................................................................ 26

16.

Nepal and Coal ......................................................................................................... 28

17.

Conclusion ............................................................................................................... 29

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1. Introduction Fossil fuels are derived from plant and animal matter. They formed naturally over millions of years. These energy-producing fuels are the remains of ancient life that have undergone changes due to heat and pressure. They are regarded as nonrenewable resources, which are limited in quantities and can be depleted. These resources are primarily fossil fuels: petroleum, coal and natural gas. Together they account for 85% of the world's energy consumption. Coal is a variety of solid, combustible, sedimentary, organic rocks that are composed mainly of carbon and varying amounts of other components such as hydrogen, oxygen, sulphur and moisture. Coal is formed through a process known as coalification, from plants growing primarily in swamp regions that has been consolidated between other rock strata and altered by the combined effects of pressure and heat over millions of years. Many different classifications of coal are used around the world, reflecting a broad range of ages, compositions and properties. Coal, the most abundant fossil fuel in the world, has been used for thousands of years as a valuable natural resource. There is supposed to be enough coal reserves worldwide to supply energy, at the current rate, for over a century. Coal provides 30.3% of global primary energy needs and generates 42% of the world's electricity. (IEA, 2011). It is the second source of primary energy in the world after oil, and the first source of electricity generation. Since the beginning of the 21st century, it has been the fastest-growing global energy source. In 2011 coal was the fastest growing form of energy outside renewable. Its share in global primary energy consumption increased to 30.3% - the highest since 1969 (WCA, 2012). The last decade’s growth in coal use has been driven by the economic growth of developing economies, mainly China. Irrespective of its economic benefits for the countries, the environmental impact of coal use, especially that coming from carbon dioxide emissions, should not be overlooked. Despite positive efforts to build more efficient plants, to retrofit old plants and to decommission the oldest, least efficient ones, the current pace is far from what is needed. Carbon capture and storage (CCS) is the most promising technology to reach near-zero CO2 emissions from large CO2 sources. Although it is developing it is far from the required deployment-level to keep CO2emissions at acceptable levels. Coal use has never stopped increasing and the forecasts indicate that, unless a dramatic policy action occurs, this trend will continue in the future. If this happens, then the IEA believes greater efforts are needed by governments and industry to embrace cleaner and more efficient technologies to ensure that coal becomes a much cleaner source of energy in the decades to come.

2. Origin of coal Coal is the altered remains of prehistoric vegetation that originally accumulated as plant material in swamps and peat bogs. The accumulation of silt and other sediments, together with movements in the earth's crust (tectonic movements)buried these swamps and peat bogs, often to great depth. The vegetation like of which may not be seen today but must have existed ages ago, was first submerged in a body of stagnant water. The cellulose of the plants was then subjected to bacterial attack. Peat was the product of such bacterial action on the plant material. Different types of peat were produced depending upon the original character of the vegetation and the intensity of the bacterial attack. Besides, the vegetal matter was substantially compacted to form peat, the precursor of coal. Peat is generally deposited in 3

slowly sinking basins where mineral matter input is very small and where ground water table can keep abreast with the formation of peat. Commonly two theories of accumulation of peat have been recognized, they explain the formation of coal seams. Drift Theory: As per this, coal seams are believed to be formed out of plants and trees which grew millions of years ago and fell down due to earth quake and tectonic activities, ground subsided and the plant material drifted, to considerable distances from their original site of growth and re-deposited as peat, to lakes, river valleys, etc., by flow of water, covered by sediments of sand and earth. The process of deposition continued for millions of years in layers and undergone geo-chemical changes such as heat, bacterial decay, pressure, etc., to form coal seams. Such coals are considered as all ochthonous coals, which are usually very rich in mineral matter. In-Situ Theory: the plants, where it grew, subsided under the earth, which after death formed peat, submerged in the water at the same place. The process ofdeposition continued in layers and undergone geo-chemical changes as explained above to form coal seams. Such coals are considered to be autochthonous coals, which generally have relatively much less mineral matter.

3. Coalification From the time peat is buried, it goes through a series of chemical and physical changes called “coalification,” which is the process that produces coals of increasing rank. Coalification is a continuing process involving increases in both temperature and pressure resulting from burial in the Earth. Burial is a process that may happen very slowly or relatively rapidly depending on the speed and magnitude of the geologic forces operating on the region. Of the two— increasing temperature and increasing pressure—increasing temperature is considered more important in promoting coalification. Higher temperatures eliminate moisture and volatile elements and, therefore, help produce coals of higher rank and higher heat (calorific) value. Higher temperatures are generally associated with deeper burial in the Earth, although proximity to an unusual source of heat, such as a volcano, could produce similar effects.

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When increases in depth of burial and temperature no longer occur, coalification slows and then ceases (unless another source of higher heat affects the coal). Thereafter, the coal will remain at the same rank if it is raised up again (either by tectonic uplift or erosion of overlying sediments, or both) into a region of much lower temperature or pressure. However, once the coal is exposed to weathering (oxidation), it is slowly reduced to the equivalent of ash. Coalification affects both the organic matter and the mineral matter in coal. As coalification precedes, organic matter, which is relatively rich in water, oxygen, and hydrogen, gradually loses those constituents and becomes relatively enriched in fixed carbon. Some of the hydrogen and carbon are converted to methane gas (CH4) in the process. Changes that occur to the mineral matter during coalification are less well understood. During coalification, clay minerals may become more refractory (that is, less affected by heat and chemicals), and the elements in other minerals may become rearranged, making them more crystalline. As a result, coalification processes produce complications for the study of coal quality. Although deeper burial (and, therefore, higher temperatures) imply older age, coals of approximately the same geologic age may exhibit a wide range in rank depending on their geologic histories. For example, Pennsylvanian coals in the Eastern United States range in rank from anthracite in easternmost Pennsylvania to high-volatile C bituminous coal in western Illinois and Iowa. The Pennsylvanian coal beds in what is now eastern Pennsylvania were subjected to strong mountain-building forces during the late Paleozoic, when the Appalachian Mountains were formed. During this time, the coal beds were forced deep into the Earth into zones of high heat and then were compressed into tight folds. In contrast, the Pennsylvanian coal beds to the west, in what is now western Pennsylvania, Ohio, Indiana, Illinois, and Iowa, were subjected to lesser depths of burial and relatively little or no mountain-building forces. During the process of coalification, sets of roughly parallel, closely spaced (fractions of an inch to several inches) fractures (cleat) form in the coal. Cleat tends to form in two sets at 5

right angles to one another; one set, the face cleat, is dominant, while the other set, the butt cleat, may be only poorly developed. Cleat is generally well developed in bituminous coals, whereas lignite and sub bituminous coals, both less well coalified, generally exhibit only incipient cleat. Anthracite in eastern Pennsylvania generally does not exhibit cleat because strong mountain-building forces, in effect, welded the coal into massive, solid beds.

4. Constituents Coal is composed of complex mixtures of organic and inorganic compounds. The organic compounds, inherited from the plants that live and die in the mires, number in the millions. Coals may contain as many as 76 of the 90 naturally occurring elements; however, most of those elements usually are present in only trace amounts (on the order of parts per million). Occasionally, some trace elements may be concentrated in a specific coal bed, which may make that bed a valuable resource for those elements (such as silver, zinc, or germanium). Some elements, however, have the potential to be hazardous (for example, cadmium or selenium), particularly if they are concentrated in more than trace amounts. Although as many as 120 different minerals have been identified in coal, only about 33 of them commonly are found in coal, and, of these, only about eight are abundant enough to be considered major constituents. The organic compounds in coal are composed of the elements carbon, hydrogen, oxygen, nitrogen, sulfur, and trace amounts of a variety of other elements. Although only a few elements compose the organic compounds found in coal, these compounds are extremely complex and, as a result, they are not well understood; however, research is being conducted into understanding organic structures in coal. The organic compounds in coal produce heat when coal is burned; they also may be converted to synthetic fuels or may be used to produce the organic chemicals.

4.1.

Minerals in Coal

The most common minerals in coal (for example illite clay, pyrite, quartz, and calcite) are made up of the most common elements (in rough order of abundance): oxygen, aluminum, silicon, iron, sulfur, and calcium. Minerals in coal commonly occur as single crystals or clusters of crystals that are intermixed with organic matter or that fill void spaces in the coal; sizes of mineral grains range from submicroscopic to a few inches. When coal is burned, most of the mineral matter and trace elements generally form ash. The mineral content of coal determines what kind of ash will be produced when it is burned.

4.2.

Macerals

The particles of organic matter in coal, inherited from the remains of plant parts, are called “macerals.” Many different types of macerals occur in coal. The identification of the original plants and their parts (such as bark, roots, spores, or seeds) that produced individual coal macerals is helpful in determining coal quality. However, these connections usually are difficult to make because the original plant material has been compressed or altered beyond recognition. Coal balls result when mineral matter (such as calcite, pyrite, or siderite) infuses and mineralizes (petrifies) a small volume of peat before it is compressed. Coal balls often contain coalified plant materials that have maintained their original structures because the mineral matter has prevented compression and degradation of the plants. Coal balls, therefore, can be used as an aid in connecting the degraded, compressed plant matter of a coal bed to the original plants.

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5. Types As geological processes apply pressure to dead biotic material over time, under suitable conditions it is transformed successively into: (Center for Climate and Energy Solutions, 2012) Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions, for example, Ireland and Finland. In its dehydrated form, peat is a highly effective absorbent for fuel and oil spills on land and water. It is also used as a conditioner for soil to make it more able to retain and slowly release water. Lignite, or brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Lignite coal deposits tend to be relatively young coal deposits that were not subjected to extreme heat or pressure, containing 25%-35% carbon. Lignite is crumbly and has high moisture content. Jet, a compact form of lignite, is sometimes polished and has been used as an ornamental stone since the Upper Paleolithic. Sub-bituminous coal typically contains 35-45% carbon. Its properties range from those of lignite to those of bituminous coal. it is used primarily as fuel for steam-electric power generation and is an important source of light aromatic hydrocarbons for the chemical synthesis industry. Bituminous coal is a dense sedimentary rock, usually black, but sometimes dark brown, often with well-defined bands of bright and dull material. It contains 45-86% carbon. Bituminous coal was formed under high heat and pressure. Bituminous coal in the United States is between 100 to 300 million year old. It is used primarily as fuel in steam-electric power generation, with substantial quantities used for heat and power applications in manufacturing and to make coke. Anthracite, the highest rank of coal, is a harder, glossy black coal. It contains 86-97% carbon, and generally has a heating value slightly higher than bituminous coal and is used primarily for residential and commercial space heating.

Type

Carbon

Moisture

Heating

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Ash

Sulphur Chlorine

Lignite Subbituminous Bituminous Anthracite

Content (%) 25-35

content (%)

(%)

(%)

(ppm)

30 - 60

Value (Btu/lb) 4,000-8,300

10-20

0.6 – 0.8

340 ± 40

35-45

10 - 45

8,500-13,000

3-12

0.7 - 4.0

340 ± 40

45-85 85-97

2 - 15 < 15

11,000-15,000 13,000-15,000

≤10 10-50

< 2.0 0.4 – 1.0

120 ± 20 120 ± 20

6. Coal Rank A major factor in determining coal quality is coal rank. Rank refers to steps in a slow, natural process called “coalification,” during which buried plant matter changes into an ever denser, drier, more carbon rich, and harder material. The major coal ranks, from lowest to highest, are lignite (also called “brown coal” in some parts of the world), subbituminous coal, bituminous coal, and anthracite. Each rank may be further subdivided.. The rank of coal is determined by the percentage of fixed carbon, moisture (inherent water), volatile matter, and calorific value after the content of mineral matter and sulfur have been subtracted from the total. Fixed carbon is solid, combustible matter left in coal after the lighter, volatile, hydrogen-rich compounds are driven off during coalification. Volatile matter is slowly removed from coal during coalification but may be rapidly removed during destructive distillation. The volatile matter contains the raw materials from which the organic chemicals are obtained. In general, the higher the rank of a coal, the more deeply it was buried, and, therefore, the higher the temperature it was subjected to during and after burial. Older coals tend to be of higher rank because they are more likely to have been buried more deeply for longer periods of time than younger coals.

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7. Coal Reserves and Resources Reserves are of practical relevance, not resource. The logic of distinguishing between reserves, which are defined as being proved and recoverable, and resources, which include additional discovered and undiscovered inferred/ assumed/ speculative quantities, is that over time production and exploration activities allow to reclassify some of the resources into reserves. It should be noted that resources are regarded as quantities in situ, 50 percent of which at most can eventually be recovered. In practice, such a reclassification has only occurred in two cases over the past two decades: in India and Australia. Indian hard coal reserves have been upgraded over time from 12.6 Mt in 1987 to 90 Mt in 2005. Australian hard coal reserves have been upgraded from 29 Mt in 1987 to 38.6 Mt in 2005. Classification of reserves according to the scheme of the World Energy Council (WEC): 



Proved amount in place is the resource remaining in known deposits that has been carefully measured and assessed as exploitable under present and expected local economic conditions with existing available technology. Proved recoverable reserves are the tonnage within the proved amount in place that can be recovered in the future under present and expected local economic conditions with existing available technology.

Classification of resources according to the scheme of the World Energy Council (WEC): 

Estimated additional amount in place is the indicated and inferred tonnage additional to the proved amount in place that is of foreseeable interest. It includes 9



estimates of amounts that could exist in unexplored extensions of known deposits or in undiscovered deposits in known coal-bearing areas, as well as amounts inferred through knowledge of favourable geological conditions. Speculative amounts are not included. Estimated additional reserves recoverable is the tonnage within the estimated additional amount in place that geological and engineering information indicates with reasonable certainty might be recovered in the future.

8. Coal Extraction/ Coal Mining: Most coal is buried under the ground. We must dig it out—mine it. The two main types of coal mining are surface (strip) mining and underground/Deep mining. Surface mining involves the removal of coal deposits close to earth's surface (usually no more than 100 feet from the surface). Topsoil and rocks are removed from the surface to expose the coal deposits. Explosives and heavy machinery are used to break up and remove layers of coal. Underground mining involves the removal of coal deposits, often hundreds of feet below the earth's surface. (Some mines may be close to 2,000 feet deep.) Shafts or tunnels are dug into the coal layers and widened to allow room for the miners and coal cars or conveyor belts. Additional shafts may be excavated to increase air ventilation for the miners. After the coal is mined, they put back the dirt and rock. They plant trees and grass. The land can be used again. This is called reclamation.

Surface Coal Mining The history of coal mining is rife with tragic occurrences. Mining accidents, methane gas explosions, violence fueled by labor strikes, and respiratory ailments - primarily Black Lung Disease- were common in the past. Over 100,000 miners have been killed in coal-mining accidents in the U.S. since 1900. So, several health and safety acts have been formulated setting stricter standards. New technologies in mining and safety regulations have greatly improved conditions for miners.

8.1.

Coal Preparation

Coal straight from the ground, known as runof- mine (ROM) coal, often contains unwanted impurities such as rock and dirt and comes in a mixture of different-sized fragments. However, coal users need coal of a consistent quality. Coal preparation – also known as coal beneficiation or coal washing – refers to the treatment of ROM coal to ensure a consistent quality and to enhance its suitability for particular end-uses. The treatment depends on the 10

properties of the coal and its intended use. It may require only simple crushing or it may need to go through a complex treatment process to reduce impurities. To remove impurities, the raw run-of-mine coal is crushed and then separated into various size fractions. Larger material is usually treated using ‘dense medium separation’. In this process, the coal is separated from other impurities by being floated in a tank containing a liquid of specific gravity, usually a suspension of finely ground magnetite. As the coal is lighter, it floats and can be separated off, while heavier rock and other impurities sink and are removed as waste. The smaller size fractions are treated in a number of ways, usually based on differences in mass, such as in centrifuges. A centrifuge is a machine which turns a container around very quickly, causing solids and liquids inside it to separate. Alternative methods use the different surface properties of coal and waste. In ‘froth flotation’, coal particles are removed in a froth produced by blowing air into a water bath containing chemical reagents. The bubbles attract the coal but not the waste and are skimmed off to recover the coal fines. Recent technological developments have helped increase the recovery of ultra fine coal material.

8.2.

Coal Transportation

The way that coal is transported to where it will be used depends on the distance to be covered. Coal is generally transported by conveyor or truck over short distances. Train sand barges are used for longer distances within domestic markets, or alternatively coal can be mixed with water to form a coal slurry and transported through a pipeline. Ships are commonly used for international transportation, in sizes ranging from Handymax (40-60,000 DWT), Panamax (about60-80,000 DWT) to large Capesize vessels (about 80,000+ DWT). Around 700 million tonnes (Mt) of coal was traded international lyin 2003 and around 90% of this was sea borne trade. Coal transportation can be very expensive – in some instances it accounts for up to 70% of the delivered cost of coal. Measures are taken at every stage of coal transportation and storage to minimize environmental impacts.

8.3.

Safety at Coal Mines

The coal industry takes the issue of safety very seriously. Coal mining deep underground involves a higher safety risk than coal mined in opencast pits. However, modern coal mines have rigorous safety procedures, health and safety standards and worker education and training, which have led to significant improvements in safety levels in both underground and opencast mining. There are still problems within the industry. The majority of coal mine accidents and fatalities occur in China. Most accidents are in small scale town and village mines, often illegally operated, where mining techniques are labor intensive and use very basic equipment. The Chinese government is taking steps to improve safety levels, including the forced closure of small-scale mines and those that fail to meet safety standards.

9. Coal Uses Coal is used to generate heat, produce electricity, and other several industrial processes – chiefly in metallurgical processes. It is used worldwide as a fuel, second only to petroleum as the most consumed energy resource. Simple burning of coal produces heat for homes and industries. Coal is a major fuel for producing electricity. The coal is burned to turn water into steam. The steam turns the blades of a turbine, which drives a generator to produce electricity. Coal is used for approximately 40 of the world's electricity production. (Wikipedia)

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Coke is a hard material produced when coal is heated without air at approximately 1000o C (1832o F). Coke (which is almost pure carbon) is used to smelt iron ore for the production of steel. Coal tar, a sticky black liquid derived from coke, is used for paving roads and tarring roofs. The extraction and distillation of coal tar into separate compounds produces a variety of products for making drugs, plastics, paints and synthetic fibers. Coal gas, composed of methane and hydrogen, is a by-product of burning coal. Coal gas was used in the 1940s for residential lighting and cooking, but it was phased out because it was expensive. Today, coal gasification processes are being developed to be more cost effective. Methanol is now being developed and used as a fuel for engines.

10. Coal and the Environment While coal makes an important contribution to economic and social development worldwide, its environmental impact has been a challenge. It is important to balance concerns for the environment alongside the priorities of economic and social development. ‘Sustainable development’ encapsulates all three areas and has been defined as: “…development that meets the needs of the present without compromising the ability of future generations to meet their own needs”.

10.1.

Coal Mining & the Environment

Coal mining – particularly surface mining –requires large areas of land to be temporarily disturbed. This raises a number of environmental challenges, including soil erosion, dust, noise and water pollution, and impacts on local biodiversity. Steps are taken in modern mining operations to minimise these impacts. Good planning and environmental management minimizes the impact of mining on the environment and helps to preserve biodiversity.

10.1.1. Land Disturbance In best practice, studies of the immediate environment are carried out several years before a coal mine opens in order to define the existing conditions and to identify sensitivities and potential problems. The studies look at the impact of mining on surface and ground water, soils, local land use, and native vegetation and wildlife populations. Computer simulations can be undertaken to model impacts on the local environment. The findings are then reviewed as part of the process leading to the award of mining permit by the relevant government authorities.

10.1.2. Mine Subsidence A problem that can be associated with underground coal mining is subsidence, whereby the ground level lowers as a result of coal having been mined beneath. Any land use activity that could place public or private property or valuable landscapes at risk is clearly a concern. A thorough understanding of subsistence patterns in a particular region allows the effects of underground mining on the surface to be quantified. This ensures the safe, maximum recovery of a coal resource, while providing protection to other land uses.

10.1.3. Water Pollution Acid mine drainage (AMD) is metal-rich water formed from the chemical reaction between water and rocks containing sulphur-bearing minerals. The runoff formed is usually acidic and frequently comes from areas where ore- or coal mining activities have exposed rocks containing pyrite, a sulphur-bearing mineral. However, metal-rich drainage can also occur in mineralised areas that have not been mined. AMD is formed when the pyrite reacts with air and water to form sulphuric acid and dissolved iron. This acid run-off dissolves heavy metals such as copper, lead and mercury into ground and surface water. There are mine management 12

methods that can minimize the problem of AMD, and effective mine design can keep water away from acid generating materials and help prevent AMD occurring. AMD can be treated actively or passively. Active treatment involves installing a water treatment plant, where the AMD is first dosed with lime to neutralize the acid and then passed through settling tanks to remove the sediment and particulate metals. Passive treatment aims to develop a selfoperating system that can treat the effluent without constant human intervention.

10.1.4. Dust & Noise Pollution During mining operations, the impact of air and noise pollution on workers and local communities can be minimized by modern mine planning techniques and specialized equipment. Dust at mining operations can be caused by trucks being driven on unsealed roads, coal crushing operations, drilling operations and wind blowing over areas disturbed by mining. Dust levels can be controlled by spraying water on roads, stockpiles and conveyors. Other steps can also be taken, including fitting drills with dust collection systems and purchasing additional land surrounding the mine to act as a buffer zone between the mine and its neighbors. Trees planted in these buffer zones can also minimize the visual impact of mining operations on local communities. Noise can be controlled through the careful selection of equipment and insulation and sound enclosures around machinery. In best practice, each site has noise and vibration monitoring equipment installed, so that noise levels can be measured to ensure the mine is within specified limits.

10.1.5. Rehabilitation Coal mining is only a temporary use of land, so it’s vital that rehabilitation of land takes place once mining operations have ceased. In best practice a detailed rehabilitation or reclamation plan is designed and approved for each coalmine, covering the period from the start of operations until well after mining has finished. Land reclamation is an integral part of modern mining operations around the world and the cost of rehabilitating the land once mining has ceased is factored into the mine’s operating costs. Mine reclamation activities are undertaken gradually – with the shaping and contouring of spoil piles, replacement of topsoil, seeding with grasses and planting of trees taking place on the mined-out areas. Care is taken to relocate streams, wildlife, and other valuable resources. Reclaimed land can have many uses, including agriculture, forestry, wildlife habitation and recreation.

10.1.6. Using Methane from Coal Mines Methane (CH4) is a gas formed as part of the process of coal formation. It is released from the coal seam and the surrounding disturbed strata during mining operations. Methane is a potent greenhouse gas – it is estimated to account for 18% of the overall global warming effect arising from human activities (CO2 is estimated to contribute50%). While coal is not the only source of methane emissions – production of rice in wet paddy fields and other agricultural activities are major emitters – methane from coal seams can be utilized rather than released tithe atmosphere with a significant environmental benefit. Coal mine methane (CMM) is methane released from coal seams during coal mining. Coal bed methane (CBM) is methane trapped within coal seams that have not, or will not, be mined. Methane is highly explosive and has to be drained during mining operations to keep working conditions safe. At active underground mines, large-scale ventilation systems move massive quantities of air through the mine, keeping the mine safe but also releasing methane into the atmosphere at very low concentrations. Some active and abandoned mines produce

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methane from degasification systems, also known as gas drainage systems, which use wells to recover methane. As well as improving safety at coal mines, the use of CMM improves the environmental performance of a coal mining operation and can have a commercial benefit. Coal mine methane has a variety of uses, including onsite or off-site electricity production, use in industrial processes and fuel for cofiring boilers. Coal bed methane can be extracted by drilling into and mechanically fracturing unworked coal seams. While the CBM is utilized, the coal itself remains unmined.

10.2.

Coal Use & the Environment

Global consumption of energy raises a number of environmental concerns. For coal, the release of pollutants, such as oxides of sulphur and nitrogen (SOx and NOx), and particulate and trace elements, such as mercury, have been a challenge. Technologies have been developed and deployed to minimize these emissions. A more recent challenge has been that of carbon dioxide emissions (CO2). The release ofCO2 into the atmosphere from human activities – often referred to as anthropogenic emissions – has been linked to global warming. The combustion of fossil fuels is a major source of anthropogenic emissions worldwide. While the use of oil in the transportation sector is the major source of energy-relatedCO2 emissions, coal is also a significant source. As a result, the industry has been researching and developing technological options to meet this new environmental challenge.

10.2.1. Technological Response Clean coal technologies (CCTs) are a range of technological options which improve the environmental performance of coal. These technologies reduce emissions, reduce waste, and increase the amount of energy gained from each tons of coal. Different technologies suit different types of coal and tackle different environmental problems. The choice of technologies can also depend on a country’s level of economic development. More expensive, highly advanced technologies may not be suitable in developing countries, for example, where cheaper readily available options can have a larger and more affordable environmental benefit.

10.2.2. Reducing Particulate Emissions Emissions of particulates, such as ash, have been one of the more visible side-effects of coal combustion in the past. They can impact local visibility, cause dust problems and affect people’s respiratory systems. Technologies are available to reduce and, in some cases, almost eliminate particulate emissions.

10.2.3. Coal Cleaning Coal cleaning, also known as coal beneficiation or coal preparation, increases the heating value and the quality of the coal by lowering levels of sulphur and mineral matter (see Section 2 for a description of coal preparation techniques). The ash content of coal can be reduced by over 50%, helping to cut waste from coal combustion. This is particularly important in countries where coal is transported long distances prior to use, since it improves the economics of transportation by removing most of the noncombustible material. Coal cleaning can also improve the efficiency of coal-fired power stations, which leads to a reduction in emissions of carbon dioxide.

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10.2.4. Electrostatic Precipitators & Fabric Filters Particulates from coal combustion can be controlled by electrostatic precipitators (ESP) and fabric filters. Both can remove over 99.5%of particulate emissions and are widely applied in both developed and developing countries. In electrostatic precipitators, particulate-laden flue gases pass between collecting plates, where an electrical field creates a charge on the particles. This attracts the particles towards the collecting plates, where they accumulate and can be disposed of. Fabric filters, also known as ‘bag houses’, are an alternative approach and collect particles from the flue gas on a tightly woven fabric primarily by sieving. The use of particulate control equipment has major impact on the environmental performance of coal-fired power stations. At the Lethabo power station in South Africa, electrostatic precipitators remove 99.8% of fly ash, some of which is sold to the cement industry. For Eskom, the plant operator, the use of ESPs has had a major impact on the environmental performance of its power stations. Between 1988 and 2003, it reduced particulate emissions by almost 85% while power generated increased by over 56%.

10.2.5. Preventing Acid Rain Acid rain came to global attention during the latter part of the last century, when acidification of lakes and tree damage in parts of Europe and North America was discovered. Acid rain was attributed to a number of factors, including acid drainage from deforested areas and emissions from fossil fuel combustion in transportation and power stations. Oxides of sulphur (SOx) and nitrogen (NOx) are emitted to varying degrees during the combustion of fossil fuels. These gases react chemically with water vapor and other substances in the atmosphere to form acids, which are then deposited in rainfall. Steps have been taken to significantly reduces SOx and NOx emissions from coal-fired power stations. Certain approaches also have the additional benefit of reducing other emissions, such as mercury. Sulphur is present in coal as an impurity and reacts with air when coal is burned to form SOx. In contrast, NOx is formed when any fossil fuel is burned. In many circumstances, the use of low sulphur coal is the most economical way to control sulphur dioxide. An alternative approach has been the development of flue gas desulphurisation (FGD) systems for use in coal fired power stations.

A Flue Gas Desulphurisation System FGD systems are sometimes referred to as ‘scrubbers’ and can remove as much as 99% of SOx emissions. In the USA, for example, sulphur emissions from coal-fired power plants 15

decreased by 61% between 1980 and2000 – even though coal use by utilities increased by 74%.Oxides of nitrogen can contribute to the development of smog as well as acid rain. NOx emissions from coal combustion can be reduced by the use of ‘low NOx’ burners, improving burner design and applying technologies that treat NOx in the exhaust gas stream. Selective catalytic reduction (SCR) and selective no catalytic reduction (SNCR) technologies can reduce NOx emissions by around 80-90% by treating the NOx post-combustion. Fluidized bed combustion (FBC) is a high efficiency, advanced technological approach to reducing both NOx and SOx emissions. FBC is able to achieve reductions of 90% or more. In FBC systems, coal is burned in a bed of heated particles suspended in flowing air. At high air velocities, the bed acts as a fluid resulting in the rapid mixing of the particles. This fluidising action allows complete coal combustion at relatively low temperatures.

10.2.6. Reducing Carbon Dioxide Emissions A major environmental challenge facing the world today is the risk of ‘global warming’. Naturally occurring gases in the atmosphere help to regulate the earth’s temperature by trapping other radiation - this is known as the green house effect. Human activities, such as the combustion of fossil fuels, produce additional greenhouse gases (GHG) which accumulate in the atmosphere. Scientists believe that the buildup of these gases is causing an enhanced greenhouse effect, which could cause global warming and climate change. The major greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, per fluorocarbons and sulphur hexafluoride. Coal is one of many sources of greenhouse gas emissions generated by human activities and the industry is committed to minimizing its emissions. Greenhouse gases associated with coal include methane, carbon dioxide (CO2) and nitrous oxide (N2O). Methane is released from deep coal mining (see earlier section). CO2 and N2Oare released when coal is used in electricity generation or industrial processes, such as steel production and cement manufacture.

10.2.7. Combustion Efficiency An important step in reducing CO2 emissions from coal combustion has been improvements in the thermal efficiencies of coal-fired power stations. Thermal efficiency is a measure of the overall fuel conversion efficiency for the electricity generation process. The higher the efficiency levels, the greater the energy being produced from the fuel. The global average thermal efficiency of coal fired power stations is around 30%, with the OECD average at around 38%. In comparison, China has an average thermal efficiency of all its installed coal-fired capacity of some 27%(though newer stations with significantly improved efficiencies are increasingly being installed).New ‘supercritical’ technology allows coal-fired power plants to achieve overall thermal efficiencies of 43-45%. These higher levels are possible because supercritical plant operate at higher steam temperatures and pressures than conventional plant. Ultra super critical power plants can achieve efficiency levels of up to50% by operating at even higher temperatures and pressures. More than 400 supercritical plant are operating worldwide, including a number in developing countries. An alternative approach is to produce a gas from coal – this is achieved in integrated gasification combined cycle (IGCC) systems. In IGCC, coal is not combusted directly but reacted with oxygen and steam to produce a ‘syngas’ composed mainly of hydrogen and carbon monoxide. This syngas is cleaned of impurities and then burnt in a gas turbine to generate electricity and to produce steam for a steam power cycle. IGCC systems operate at high efficiencies, typically in the mid-40s but plant designs offering close to 50% efficiencies are available. They also remove 95-99% of NOx and SOx emissions. Work is being undertaken to make further gains 16

in efficiency levels, with the prospect of net efficiencies of 56% in the future. There are around 160 IGCC plants worldwide. IGCC systems also offer future potential for hydrogen production linked with carbon capture and storage technologies (described in more detail in the next section).

An Integrated Gasification Combined Cycle Unit

10.2.8. Carbon Capture & Storage An important factor in the future use of coal will be the level to which CO2 emissions can be reduced. Much has been done to achieve this, such as the improvements in efficiency levels. One of the most promising options for the future is carbon capture and storage (CCS).Carbon capture and storage technologies allow emissions of carbon dioxide to be stripped out of the exhaust stream from coal combustion or gasification and disposed of in such a way that they do not enter the atmosphere. Technologies that allow CO2 to be captured from emission streams have been used for many years to produce pure CO2 for use in the food processing and chemicals industry. Petroleum companies often separate CO2from natural gas before it is transported to market by pipeline. Some have even started permanently storing CO2 deep underground in saline aquifers. While further development is needed to demonstrate the viability of separating out CO2from high volume, low CO2 concentration flue gases from coal-fired power stations, carbon capture is a realistic option for the future. Once the CO2 has been captured, it is essential that it can be safely and permanently stored. There are a number of storage options at various stages of development and application. Carbon dioxide can be injected into the earth’s subsurface, a technique known as geological storage. This technology allows large quantities of CO2 to be permanently stored and is the most comprehensively studied storage option. As long as the site is carefully chosen, the CO2 can be stored for very long periods of time and monitored to ensure there is no leakage. Depleted oil and gas reservoirs are an important option for geological storage. Latest estimates suggest that depleted oilfields have a total capacity of some 126Gigatonnes (Gt) of CO2. Depleted natural gas reservoirs have a considerably larger storage capacity of some 800 Gt of CO2. Unmineable coal beds are estimated to have a storage capacity of some 150 Gt of CO2.Large amounts of CO2 can also be stored in deep saline water-saturated reservoir rocks, allowing countries to store their CO2emissions for many hundreds of years. Firm estimates of 17

the CO2 storage capacity in deep saline formations have not yet been fully developed, though it has been estimated that it could range between 400 and 10,000 Gt. There are a number of projects demonstrating the effectiveness of CO2 storage in saline aquifers. The Norwegian company Statoil is undertaking a project at the Sleipner field located in the Norwegian section of the

Underground Storage Options for CO2 The storage of CO2 can also have an economic benefit by allowing increased production of oil and coal bed methane. These techniques are referred to as Enhanced Oil Recovery (EOR) and Enhanced Coal Bed Methane recovery (ECBM). The CO2 can be used to ‘push’ oil out of underground strata and is already widely used in the oil industry. The Weyburn Enhanced Oil Recovery project uses CO2 from a lignite-fired power station in the USA and transports it through a 205 mile pipeline to the Weyburn oilfield in Canada to boost oil production. Around 5000 ton or 2.7 m3 of CO2 per day are injected into the oilfield, an amount which would otherwise have been released into the atmosphere. ECBM allows CO2 to be stored in unmineable coal seams and improves the production of coal bed methane as a valuable byproduct. Carbon capture and storage offers the potential for the large-scale CO2 reductions needed to stabilize atmospheric concentrations of CO2.

10.2.9. Coal & Renewable Energy The continued development and deployment of renewable energy will play an important role in improving the environmental performance of future energy production. However, there are a number of significant practical and economic barriers that limit the projected rate of growth of renewable energy. Renewable energy can be intermittent or unpredictable and ‘site-dependent’, which means they are only available at specific locations. Wind energy, for example, depends on whether and how strongly the wind is blowing and even the best wind farms do not normally operate for more than about one third of the time. Many forms of biomass are seasonal and can be difficult to transport. Coal-fired electricity can help support the growth of renewable energy by balancing out their intermittencies in power supply. Coal can provide convenient, cheap 18

base-load power while renewable can be used to meet peak demand. The economics and efficiency of biomass renewable can also be improved by co-firing with coal. While clean coal technologies are improving the environmental performance of coal-fired power stations, its role as an affordable and readily available energy source offers wider environmental benefits by supporting the development of renewable.

10.2.10.

Overcoming Environmental Impacts

The environmental impact of our energy consumption is a concern for us all. Limiting the negative effects of coal production and use is a priority for the coal industry and one which has been the focus of research, development and investment. Much has been achieved – technologies have been developed and are widely used to limit particulate emissions, NOx and SOx and trace elements. Improvements in the efficiency of coal combustion have already achieved significant reductions in carbon dioxide emissions. The wider use of technologies to improve the environmental performance of coal will be essential, particularly in developing countries where coal use is set to markedly increase. Technological innovation and advancement, such as carbon capture and storage, offers many future prospects for tackling CO2emissions from coal use in the future.

19

11. World coal Activity Coal provides 30.3% of global primary energy needs and generates 42% of the world's electricity. (IEA, 2011). It is the second source of primary energy in the world after oil, and the first source of electricity generation. Since the beginning of the 21st century, it has been the fastest-growing global energy source. In 2011 coal was the fastest growing form of energy outside renewable. Its share in global primary energy consumption increased to 30.3% - the highest since 1969 (WCA, 2012).

Consumption by fuel - 2011 2% 6% Oil

5% 33%

Natural gas Coal Nuclear energy

30%

Hydro electricity Renew- ables

24%

Energy Consumption growth 2009-2011

12. Coal Reserves There are two internationally recognized methods for assessing world coal reserves. The first one is produced by the German Federal Institute for Geosciences and Natural Resources (BGR) and is used by the IEA as the main source of information about coal reserves. The second one is produced by the World Energy Council (WEC) and is used by the BP Statistical Review of World Energy. According to BGR there are 1004 billion tonnes of coal 20

reserves left, equivalent to 130 years of global coal output in 2011. Coal reserves reported by WEC are much lower - 861 billion ton, equivalent to 112 years of coal output. Coal reserve is available in almost every country worldwide, with recoverable reserves in almost 80 countries and is actively mined in more than 70 countries. Six countries dominate coal globally 85 percent of global coal reserves are concentrated in six countries (in descending order of reserves): USA, Russia, India, China, Australia, and South Africa. The USA alone holds 30 percent of all reserves and is the second largest producer. China is by far the largest producer but possesses only half the reserves of the USA. Therefore, the outlook for coal production in these two countries will dominate the future of global coal production. Largest coal producers in descending order are: China, USA (half of Chinese production), India, , Australia, South Africa, and Russia. These countries account for over 80 percent of global coal production.

Million tonnesCoal: Proved Reserves at end 2011

Coal: Proved Reserves at end 2011 250000 200000 150000 100000 50000 0

Anthraciteand bituminus

Sub-bituminousand lignite

The current estimates of hard coal reserves, based on what is known about worldwide economically recoverable reserves are in the range of 723 billion tonnes or approximately 620 billion tonnes of coal equivalent. This latest estimate comes from the German Federal Institute for Geosciences and Natural Resources (BGR). BGR estimates hard coal resources in 2010 at 17,167 billion tonnes. The ratio between resources and reserves is approximately 23.7:1 and has substantially improved since the previous BGR estimate (21:1), because the volume of resources has risen dramatically. The world’s coal resources are nowhere near as well documented as oil and gas resources. Coal reserves currently have a remaining life of approximately 120 years based on an output of 6.1 billion tonnes using 2009 data. Hard coal has a share of approximately 53% of the total energy reserves of approximately 1,360 billion tonnes of coal equivalent including all fossil sources of energy and uranium. With resources of 14,591 billion tonnes of coal equivalent, coal has ever greater share of resources – 75% of the 19,332 billion tonnes of coal equivalent total. Compared to hard coal, oil reserves (24% of total reserves) are adequate for 40-45 years and gas reserves for 60-65 years at current production levels. 21

13. Coal Production

Coal Production History 9000.0 8000.0 7000.0 US

5000.0

Total World

4000.0

China

3000.0

India

2000.0

Total Europe & Eurasia

1000.0

Coal: Production *

Million tonnes US Canada Germany Kazakhstan Russian Federation United Kingdom South Africa Australia China India Japan Total World

2010

2011

2009

Change 2011 over 2010 2011

983.7 992.8 69.0 68.2 182.3 188.6 110.9 115.9 321.6 333.5 18.4 18.3 254.3 255.1 424.0 415.5 3235.0 3520.0 573.8 588.5 0.9 1.3 7254.6 7695.4

22

2007

2005

2003

2001

1999

1997

1995

1993

1991

1989

1987

1985

1983

0.0 1981

Mt

6000.0

2011 share of total

0.9% 14.1% -1.2% 0.9% 2.1% 1.1% 4.5% 1.5% 4.1% 4.0% -0.4% 0.3% 0.3% 3.6% -2.2% 5.8% 8.8% 49.5% 2.3% 5.6% 38.7% 6.1% 100.0%

Coal Production 4000.0 3500.0 3000.0 2500.0 2000.0 1500.0 1000.0 500.0 0.0

2010 2011

Coal consumption mainly takes place in the country of origin. Only 15 percent of production is exported, 85 percent of produced coal is consumed domestically. Largest net coal exporters in descending order are: Australia, Indonesia (40 percent of Australian export), South Africa, Colombia, China, and Russia. These countries account for 85 percent of all exports with Australia providing almost 40 percent of all exports. The fastest reserves depletion worldwide is taking place in China with 1.9 percent of reserves produced annually. (World Coal Web site, 2013)

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14. Coal Consumption

Coal Consumption History 4000.0 3500.0

2500.0

US

2000.0

China India

1500.0

Total World 1000.0

Total Europe & Eurasia

500.0

Coal: Consumption *

Million tonnes oil equivalent US Canada Germany Kazakhstan Russian Federation United Kingdom South Africa Australia Bangladesh China China Hong Kong SAR India Japan Total World

2010

2011

526.1 501.9 24.0 21.8 76.6 77.6 31.6 30.2 90.2 90.9 31.0 30.8 91.3 92.9 43.8 49.8 0.9 1.0 1676.2 1839.4 6.3 7.7 270.8 295.6 123.7 117.7 3532.0 3724.3

24

2011

2009

2007

2005

2003

2001

1999

1997

1995

1993

1991

1989

1987

1985

1983

0.0 1981

Mtoe

3000.0

Change 2011 over

2011 share

2010

of total

-4.6% 13.5% -9.1% 0.6% 1.2% 2.1% -4.5% 0.8% 0.8% 2.4% -0.7% 0.8% 1.7% 2.5% 13.6% 1.3% 6.1% 9.7% 49.4% 21.4% 0.2% 9.2% 7.9% -4.8% 3.2% 5.4% 100.0%

Mtoe

Coal Consumption 2011 2000.0 1800.0 1600.0 1400.0 1200.0 1000.0 800.0 600.0 400.0 200.0 0.0

25

15. Coal Trade Most coal is consumed domestically and only 15% is traded internationally. In a number of countries coal is also the only domestically available energy fuel and its use is motivated by both economic and energy security considerations. This is the case in countries and regions such as Europe, China and India, where coal reserves are much higher than oil or gas reserves. Most of the world’s coal exports originate from countries which are considered to be politically stable – a characteristic which reduces the risks of supply interruptions. The world market for hard coal globally grew by 15% in 2010, reflecting recovery from the world economic crisis. World coal trade developed as follows: (EIA, 2015) World Output / Seaborne World Trade 2000

2010

World Output

3800 Mt

6720 Mt

World Trade

530 Mt

963 Mt

Share of world trade in output

13.9 %

14.3 %

Hard Coal

The world market for hard coal was therefore stable in 2010. Because of economic recovery in the steel industry of OECD countries, seaborne trade included a distinct increase of coking coal exports. The market for steam coal also continued to grow. Overland trade increased sharply, by approximately 33 million ton. The share of the world trade in total production has risen slightly since 2000. However, most coal output is consumed in the country where it is produced. The seaborne traded volume breaks down into a coking coal market and a steam coal market. The steam coal market in turn comprises the Pacific and Atlantic markets, characterized by different supply structures. The quantities, exchanged between both market, Amounted in 2010 to approximately 8% or 79 million ton of the steam coal market. About 12% of global steam coal production was delivered to consumers by sea. The coking coal market, in contrast, is a more uniform global market due to the small number of supply countries on the one hand, and to the worldwide distribution of demand on the 26

other hand. About 28% of world production was traded internationally in 2010, a significantly greater share than for steam coal. Differences in trends were observed in the two segments of world coal trade. The following comments refer only to seaborne hard coal trade. The major import countries are found mainly in Southeast Asia. In addition to Japan, South Korea and Taiwan, China has also become a major coal importer. India also pushed its way further up the ranking. In Europe, Germany and the United Kingdom imported most coal.

Seaborne trade 2010

Coal Prices 700.00

Japan steam coal import cif price

$US per tonne

600.00 500.00

Japan coking coal import cif price

400.00

US Central Appalachian coal spot price index Northwest Europe marker price

300.00 200.00 100.00 0.00 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

It is seen that the coal price over the decade is fairly stable. It is due to widespread distribution of coal deposits around the globe which are being discovered one after another. However, with increased consumption and the increased global trade, coal prices, like much of the energy commodity complex, began a run-up in both volatility and value in 2004. The 27

price increased for both coking and steam coal were in line with the increase seen in other commodities such as crude oil and crude products, which is reflective of coal's status as a highly traded and valued energy commodity. Though prices outside of the Asian markets had moderated considerably from the highs of 2008, a number of competing factors are at play, the outcome of which is most certainly going to be higher prices. Though the IEA reports a possible tripling of prices over the next 5 years, that forecast is based upon a large number of variables whose outcomes are less than certain. There is little doubt however that if:   

China's economic growth results in continued ramping up of coal demand in line with current trends, and India's growth in demand cannot be at least partially offset through the opening of new production due to environmental regulation, and The continuing global economic recovery results in significantly increased demand for both electricity and steel,

But local market dynamics can be assumed to persist. Thermal coal prices have fallen steadily in the past 10 months but price volatility remains a key feature of coal markets and companies will need expertise and technology to help manage it.

16. Nepal and Coal In Nepal low to medium grade coal occurrences/ deposits are known in four stratigraphic positions e.g. (i) Quaternary lignite (ii) Siwalik coal (iii) Eocene Coal and (iv) Gondwana coal. Peat/ lignite in Kathmandu valley is mined and used mainly in brick burning. Siwalik coal is not economically attractive because of scattered small lenses. Eocene Coal occurs as irregular seams confined to orthoquartzite in Tosh, Siuja, Azimara and Abidhara in Dang, Sallyan, Rolpa, Pyuthan and Palpa districts. Small scale 20 coal mines are in operation in these districts. In addition to that 49 prospecting license are also issued by DMG. Present Coal production in Nepal is insignificantly small (150 -250mt/day).

28

Primary production and import of coal resources in Nepal

17. Conclusion In Nepal, coal is present in scattered amount in most of the areas. Therefore, Nepal is not able to generate sufficient energy from coal, an energy resource. Coal is a non renewable energy, and can’t be used again once its finish. Therefore we think about developing and promoting renewable energy which can be used again and again. Coal have greater impact to the environment too as they release heavy carbon dioxide when they burn. So, people think about environment friendly coal burning and consumption. So, that they can be consume with less effect to the environment.

29

Bibliography (2012). Retrieved from Center http://www.c2es.org/energy/source/coal

for

Climate

and

Energy

Solutions:

(2013). Retrieved from World Coal Web site: http://www.worldcoal.org/coal/coal-mining/ EIA. (2015, 1 20). Retrieved http://www.eia.gov/coal/annual/

from

Independent

Statistics

IEA. (2011). WCA. (2012). World Coal Association. Wikipedia. (n.d.). Retrieved from http://en.wikipedia.org/wiki/Coal

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and

Analysis: