Coal plays an important role as a primary and an inexpensive source for power generation. In 2003, the USA produced 1,069 million short tons of coal and consumed during the same period 1,090 million short tons.
The electric power sector accounted for over 90 per cent of the US coal consumption. In 2003, the USA generated 3,691 billion kwh of electricity from electric power sector, out of which coal-fired plants accounted for 53 per cent of generation, nuclear 21, natural gas 15, hydroelectricity seven and oil three per cent.
In many other developed countries coal is being used as the primary source for power generation. In Pakistan, coal currently makes up merely one per cent of the electric power generation.
Coal is primarily classified into four major categories, or 'ranks': lignite, sub-bituminous, bituminous and anthracite. One of the most valuable content of coal is its carbon content which supplies most of its heating value.
However, various other factors as moisture content, ash content and sulphur are also important in determining the rank of a particular coal. Anthracite, is top ranked coal, with highest carbon content that ranges between 86-98 per cent and has a heat value of nearly 15,000 BTUs (British thermal units) per pound.
Bituminous and sub-bituminous 'ranks' of coal are inferior to anthracite. The bituminous variety is used primarily to generate electricity and to make coke for the steel industry.
The discovery of coal in Balochistan during the late 18th century led to its commercial utilization mainly by the North-Western Railways during the colonial regime. At present, our total coal reserves are estimated around 184.5 billion tonnes. which include the lately discovered deposits of low sulphur coal at Thar.
The local coal falls in the lignite and sub-bituminous categories. Coal from Lakhra and Sonda fields of Sindh has relatively higher moisture, sulphur and ash contents.
As opposed to this, Thar coal having an estimated reserves of 184.6 billion tonnes is much superior in quality due to low sulphur content and higher heating value. Well-developed coal-fields are located in Punjab, Balochistan and Sindh.
SINDH: The Sindh province has total coal resources of 184 billion tonnes. The quality of coal is mostly lignite-B to sub-bituminous A-C. Brief description of two major deposits is given as under:
THAR: A large coal-field, having a resource potential of about 175 billion tonnes, has been discovered at Thar in the eastern part of the province, about 400 km South East of Karachi.
The coal-field extends over 9,000 sq km area out of which 356 sq km area has been studied in detail by the Geological Survey of Pakistan proving nine billion tonnes coal in four blocks.
The main coal bed thickness ranges from 12 to 21 meters at an average depth of 170 meters, upper 50 meters being loose sand. The quality of coal has been determined on the basis of chemical analyses of more than 2,000 samples. The rank of the coal ranges from lignite-B to sub-bituminous-A.
LAKHRA: The Lakhra coal-field in Dadu District, lies 16 km to the west of Khanot railway station on the Kotri-Dadu section of the Pakistan Railways. It covers approximately an area of about 200 sq km. It is well connected with Karachi and Hyderabad through roads and railways. Mining in the area is done underground.
Three coal seams are established in the field but generally only the middle seam is known, as Lailian bed possesses the necessary persistence and thickness for consideration in large-scale mining. It shows a variation in thickness from 0.75 meter to 2.5 meters.
Average thickness is 1.5 meter. Coal from Lakhra has an apparent rank of lignite A to sub-bituminous C. The coal is dull black and contains amber resin flakes and about 30 per cent moisture. Although it can be extracted in large lumps, it dries to a moisture content of about 8 per cent when brought to surface.
It tends to crumble on longer exposure to atmosphere and is often susceptible to spontaneous combustion. Based essentially on the results of the initial exploratory work done by the GSP, more detailed exploration has been subsequently undertaken by PMDC, JICA, Wapda and the USAID.
The total reserves of the deposit have been estimated to be 1328 million tonnes with 244 million tonnes measured, 629 indicated and 455 tonnes inferred. Average annual production of coal from Lakhra is over one million tonnes. Most of this production is used in the WAPDA power plant at Khanote, Sindh and in brick kiln industry.
SONDA-JHERRUCK: Over one billion tonnes reserves of lignite quality coal have been assessed in Sonda- Jherruck coal-field. Owing to favourable location and developed infrastructure, two Chinese companies have expressed interest to conduct feasibility study for commissioning of 500 mw power generation units.
In case the feasibility study justifies commissioning of project, an investment of $500 million would be made by the Chinese consortium for establishment of coal fired power project of 500 mw. A quantity of two million tonnes coal annually would be mined to cater for the requirements of power generation units.
Balochistan: The coal seams in Balochistan are found in Ghazig formation of Eocene age. The quality of the coal is sub-bituminous A to high volatile B bituminous. The coal-fields mostly lie around Quetta in Balochistan however the following are significant:
SOR-RANGE; DEGARI; SINJIDI: Sor-Range-Degari coal-field lies 13 to 25 km south east of Quetta covering an area of about 50 sq km and is easily accessible through metalled road from Quetta.
The northern half of the field is known as Sor Range, Degari is situated at the southern end of the field. The thickness of the coal seam varies from 1.0 meter to 2.0 meters but in Sor-Range seam sections up to 5.0 meters have been encountered. The coal is of better quality with low ash and sulphur content. The quality of the coal is high sub-bituminous A to high volatile B bituminous.
CHAMALANG: These are the newly discovered coal-fields which need development. Preliminary work done by GSP in these areas has indicated that it has a good potential.
The quality of coal is also better as compared to the rest of Balochistan. The rank of the coal ranges from high volatile C bituminous to high Volatile A-bituminous with a total resource of 6 million tonne. Its heating value is +12000 BTU/lb.
PUNJAB: The Punjab's coal fields comprise the eastern, central and western Salt Range between Khushab, Dandot and Khewra while Makerwal coal-field lies in Trans-Indus Range (Sanghar Range). The rank of the coal is sub-bituminous A to high volatile bituminous.
SALT RANGE: The Salt Range coal-field covers an area of about 260 sq km, between Khushab, Dandot and Khewra. The entire coal producing area is well connected with roads and railways.
The top seam varies in thickness from 0.22 meter to 0.30 meter while the middle seam is up to 0.60 meter thick. The lower seam is up to one meter thick and is relatively of better quality.
It is being mined in Dandot, Choa-Saiden Shah and adjoining areas. The Punjab Mineral Development Corporation and several private companies are operating the mines in the area. Reserve of the deposit is 235 million tonnes.
MAKERWAL/GULLAKHEL: Makerwal/Gullakhel coal-field is situated in Sarghar Range (Trans-Indus Range). The coal-field extends from about 3.2 km west of Makerwal to about 13 km West of Kalabagh covering an area of about 75 sq km, in Mianwali district. The quality of Makerwal/Gullakhel coal is better than that of Salt Range coal and is preferred by the consumers. Total reserves of the deposit are 22 million tonnes.
Lignite, the indigenous coal mostly found in Pakistan is a comparatively young coal geologically speaking and has the lowest carbon content of just 25-35 per cent and also the lowest heat value of only 6,000-10,000 BTUs per pound.
However, lignite, which is called 'brown coal', can be used for electric power generation. Lignite found in Thar has comparatively lower sulphur content, makes it more suitable for power generation after the washing process and an appropriate plant design.
The local production of coal is estimated at 3.21 million tons out of which presently over 80 per cent is being utilized by bricks makers, while the rest are being consumed by the cement industry to blend it with the imported coal to reduce the production cost, and only one per cent by the coal-based power stations.
It is reported that around 85 per cent of the cement industry has shifted on low-priced coal from relatively more expensive natural gas and furnace oil. The conversion has small impact on the local coal production because cement units are using high rank imported coal as the indigenous coal is of low quality.
Indigenous coal is blended with imported coal in small proportion, which is necessary for smooth operation of the plant. During the 2002, the cement industry utilized one million tons of imported coal from South Africa, Austria and Indonesia. Imported coal cost Rs3150 to Rs3510 per ton while local coal cost Rs1300 to Rs2500 per ton.
Use of coal as fuel in sugar industry can save around 9 million tons bagasse, which can be utilized to produce medium density fibreboard, excellent replacement of furniture-making wood and consequently saving our fast depleting forests.
Coal is also an important raw material for the production of several chemicals. Refined coal tar can be used in the manufacture of a range of chemicals including pitch, creosote oil, naphthalene, phenol, pyridine, benzene, toluene, xylene, ethylene, propylene, polyesters, plastics, synthesis gas, acetic acid, acetic anhydride.
Numerous chemicals and fuels can be manufactured from the gasification of coal. In late 1950's, Pak-American Fertilizers, Iskandarabad, Daudkhel was based on gasification technology supplied by Lurgi to produce ammonia and ammonium sulfate fertiliser.
Sasol of South Africa has developed the processes for production of petrochemicals from coal, with high ash content by gasification. Coal under pressure and high temperature, in the presence of steam and oxygen is converted to raw gas.
Condensation and subsequent cooling of gas, yields co-products such as tar and oil. Nitrogenous compounds (Ammonia), sulfur and phenolic compound are also recovered. The purified synthesis gas after cooling is made available for conversion to synthetic fuels and or chemical production. Sasol acquired the technology from Lurgi (Germany).
South African coal reserves are largely bituminous with relatively high ash content (about 45%) and low sulfur content (1%). The advantage of SASOL process is that it can process low-grade coal and a number of high value chemicals are produced along with synthetic fuels. It is understood that Sasol or similar technology can be adopted for our coal reserves.
It's time to explore coal and develop coal-fired power plants to not only lessen dependence on imported fuel but also to cut the cost of power production for the benefit of the industries, trade and individual consumers.
The government should also consider the utilization of indigenous coal for coal gasification, to produce high value petrochemicals, for which suitable technologies are available in the world.
|Table - 1
Coal Production (Thousand Tonnes)
|Pir Ismail Ziarat||02||02||08||-||12|
|Eastern Salt Range||21||16||02||145||235|
|Central Salt Range||29||-||-|