Coal
Bituminous coal is the basic and most important source of energy in Poland. While it may have a heating value of up to 13,100 Btu per pound (7,278 kcal/kg), such as that mined in Slask (Silesia) in southwest Poland, that used at the Leg plant has a value of 8,640 Btu per pound (4,800 kcal/kg) (Krakow-Leg; Czajkowski and Dziarzawski 1988).Bituminous, or "soft," coal is a black, soft, dusty fuel and is used in large quantities for Krakow's power generation and steel making. It is also widely used for home heating and occasionally for coal gasification. It is found as a high-volatility moist coal and as a low-volatility dry coal. While it can have from 0.5% to more than 8% sulphur content, the 1988 average at the Leg plant was 0.83% (Bartok 1982).
Poland's coal mines extend as much as 1.2 miles (2,000 meters) below the surface. According to 1980 estimates, its coal reserves total 150 billion tons, located mainly in Slask (Silesia). Lignite reserves are estimated at 40 billion tons. The most effective use of this coal is to burn it in boilers located in large electrical generating stations, generally located near the Mines. It is estimated that, with these reserves and extraction of 190 million tons per year, there would be enough coal for several decades to a century, depending on the annual growth rate and future discoveries (Kamler 1979).
Coal Gas and Coke
Coal gas has been widely used in Poland. It is produced from bituminous coal by heating it in an oven to above l,832 F (l,000 C) for 10 hours or more in the absence of oxygen. The volatiles are driven off and captured. The coal gas is often employed for residential cooking. The heat output is between 400 and 600 Btu per ft3 (3,562 aad 5,343 kcal/m3). Coal gasification started in Poland in 1847 in the city of Wroclaw, then in Szczecin in 1848, Warsaw in 1856, and Krakow in 1857; today it is used by more than 400 cities and towns. At first coal gas was mainly used for lighting streets. Later it was used residentially for cooking, hot water, and home heating. The Krakow system ceased coal gas production in 1968 (Socha 1989).The coke remaining from the coal gasification process is also used as a fuel. It burns with little or no smoke and is important in metallurgical work for heating and in small residential boiler houses. Its heating value is about the same as bituminous coal, but only 1,200 to 1,400 pounds (544 to 635 kg) of coke can be obtained from a ton of coal. The conversion from coal to coke and coal gas yields about 90% of the original heating value of the coal, shown by the following formula:
where
E = [(Qcoke/Qcoal) * HVcoke] + [Qgas * HVgas]
HVcoal* 100% E = efficiency of conversion,
Qcoal = original quantity of coal,
Qcoke = quantity of coke produced,
Qgas = quantity of coal gas produced,
HVcoal = heating value of the original coal (ave. 26.2 MBtu/ton),
HVcoke = heating value of the coke produced (ave. 26.0 MBtu/ton), and
HVgas = heating value of the gas produced (avg. 500 Btu/ft3.One ton of coal (2,000 lb) normally yields an average of 1,400 lb of coke and 11,000 ft3 of coal gas (modified from Putnam 1953).
Natural Gas
The use of natural gas has risen in recent years, largely in central heating systems. Because the major quantity must be imported, a continued increase in its use depends on future discoveries, its availablity from neighboring countries, and its price. Areas of Poland, including the Krakow region, have nonetheless been abandoning coal gas and using more and more natural gas, both from domestic and foreign sources. Development of gas distribution systems in Poland progressed at an estimated annual rate of 620 miles (l,000 km) in recent years (Czajkowski and Dziarzawski 1988). Further growth in natural gas consumption is in question because of recent increases in prices charged to consunkrs and by tenfold price increases on gas imported from the Soviet Union.