ORIGIN AND Nature OF COAL Coal is a fossil fuel composed essentially of compressed altered plant remains. Under circumstances which have been replicated in many places on the planet over the past 350 to 400 million years, plant tissue has been buried under anoxic (oxygen- free) conditions, allowing plant tissue to be incompletely decomposed by anaerobic bacteria. Economically viable coal deposits form when remains of entire forests are buried and preserved by later sediments. Over millennia,such buried plant tissue may be converted through a series of stages involving microbial activity, pressure,and heat into peat, lignite, sub-bituminous, and bituminous coal,or the rarest coal, anthracite, the form of coal with the highest amount of energy per kilogram. Coal is composed predominantly of the element carbon ( C ) along with hydrogen ( H ) and nitrogen ( N ) . Carbon content of coal ranges from 45 percent up to as much as 98 percent in rare anthracite. Most coal used to produce electricity contains between 50 and 70 percent carbon. Buming coal,therefore, produces large amounts of , themain agent of global climate change. Question 4: Burning 1 kilogram of C produces about 3.7 kilograms of CO 2 . Assume typical coal contains 60 percent C . How much CO 2 is released per tonne of coal burned? Question 5: Recall that the United States produces about 1,100 million tons of coal each year-equal to 1,000 million tonnes. How much CO 2 would be released each year? Question 6: Slightly more than 4,000 million tonnes of coal were burned globally in 2003. How much CO 2 was produced, assuming 60 percent C content? Question 7: According to the World Coal Institute, the world is expected to consume 7,000 million tonnes of coal each year by 2030, with China accounting for half the projected increase. How much CO 2 would be produced by coal burning in 2030 ? Question 8: How can global CO 2 emissions be controlled, in your view, if these forecasts prove accurate? Discuss the implications if they are not controlled. DAL BED METHANE When plant matter is converted into coal,methane is also formed,the main ingredient in natural gas. The methane may be trapped in the sedimentary rock containing the coal. Some of this trapped gas is released when coal is mined, which can lead to dangerous explosions. These explosions are the reason for most miners' deaths in underground mines. Large mines may release up to 1 million cubic feet per day of methane. This can be a significant souree of atmospheric methanc, a powerful greenhouse gas. It is also a potentially valuable energy resource. OXIDAtion of Pyrite and Water PolLUTION One of the most widespread and polluting reactions is that of the oxidation of the minetn): pyrite, illes galled "fool's gold." Pyrite is found in virtually all coals as well as in the When the coal is stripped away,the pyrite-bearing sediment is exposed to oxidation fossil soils immediately below the coal seams: and hydration,producing sulfaric acid. The.

1. ORIGIN AND Nature OF COAL Coal is a fossil fuel composed essentially of compressed
altered plant remains. Under circumstances which have been replicated in many places on the
planet over the past 350 to 400 million years, plant tissue has been buried under anoxic (oxygen-
free) conditions, allowing plant tissue to be incompletely decomposed by anaerobic bacteria.
Economically viable coal deposits form when remains of entire forests are buried and preserved
by later sediments. Over millennia,such buried plant tissue may be converted through a series of
stages involving microbial activity, pressure,and heat into peat, lignite, sub-bituminous, and
bituminous coal,or the rarest coal, anthracite, the form of coal with the highest amount of energy
per kilogram. Coal is composed predominantly of the element carbon ( C ) along with hydrogen (
H ) and nitrogen ( N ) . Carbon content of coal ranges from 45 percent up to as much as 98
percent in rare anthracite. Most coal used to produce electricity contains between 50 and 70
percent carbon. Buming coal,therefore, produces large amounts of , themain agent of global
climate change. Question 4: Burning 1 kilogram of C produces about 3.7 kilograms of CO 2 .
Assume typical coal contains 60 percent C . How much CO 2 is released per tonne of coal
burned? Question 5: Recall that the United States produces about 1,100 million tons of coal each
year-equal to 1,000 million tonnes. How much CO 2 would be released each year? Question 6:
Slightly more than 4,000 million tonnes of coal were burned globally in 2003. How much CO 2
was produced, assuming 60 percent C content? Question 7: According to the World Coal
Institute, the world is expected to consume 7,000 million tonnes of coal each year by 2030, with
China accounting for half the projected increase. How much CO 2 would be produced by coal
burning in 2030 ? Question 8: How can global CO 2 emissions be controlled, in your view, if
these forecasts prove accurate? Discuss the implications if they are not controlled. DAL BED
METHANE When plant matter is converted into coal,methane is also formed,the main ingredient
in natural gas. The methane may be trapped in the sedimentary rock containing the coal. Some of
this trapped gas is released when coal is mined, which can lead to dangerous explosions. These
explosions are the reason for most miners' deaths in underground mines. Large mines may
release up to 1 million cubic feet per day of methane. This can be a significant souree of
atmospheric methanc, a powerful greenhouse gas. It is also a potentially valuable energy
resource. OXIDAtion of Pyrite and Water PolLUTION One of the most widespread and
polluting reactions is that of the oxidation of the minetn): pyrite, illes galled "fool's gold." Pyrite
is found in virtually all coals as well as in the When the coal is stripped away,the pyrite-bearing
sediment is exposed to oxidation fossil soils immediately below the coal seams: and
hydration,producing sulfaric acid. The shale above coal seams also contains a lot of pyrite,and
shales are often left on "spoil heaps"to oxidize. Strip-mining coal may thes lend to extensive
acidification of surface water. AIR POLLUTION FROM COAL COMBUSTION In addition to
Galkurning can produce (I) high levels of toxic sulfur oxide gases (SOx),(2) appreciable
quantities of toxic heavy metals such as mercury,uranium, and chromium,and (3) oxides of
nitrogen (NOx). SOx and NOx can contribute to stnog and acid precipitation, which can damage
buildings and cause pulmonary problems. Heavy metals can build up in plant tissue and the
tissue of aquatic organisms. Coal burning is a major contributor of mercury ( Hg ) to the
environment. Mercury les. els in freshwater and marine fish in many states are high enough to
trigger health waming Levels of methylmercury, the most toxic form, that might not ham an
adult can damage a child's developing brain,lead to deficiencies in IQ,cause attention deficit, and
impair motor function. Fetuses and infants are especially vulnerable. Figurelais a map of the
United States showing fish advisories due to methylmercury contamination. Atmospheric
mereury concentration is shown in Figurelb. About two-thirds of SOx and about onefourth of

2. NOx is from coal-burning power plants. Question 9: What regions of the United States are most
susceptible to atmospheric merciry contamination? FIGURE la Map of the United States
showing fish advisories related to methylmercury contamination (USGS). FIGURE 1b Modeled
Atmospherie Mercury Deposition (2005, from USGS). An "average"500-megawatt coal-burning
power plant each year emits pollutants as shown in Tablel. TABLE I Emissions of an average
500 -megawatt coal-fired power plant (EPA). COAL AS A RESOURCE At this juncture you
might be asking yourself (1) if coal mining is so hazardous to miners and produces significant
levels of water pollution.(2) if levols are rising appreciably due in large part to coal buming,and
(3) if coal burning is responsible for much if not most of the air pollution in developing
countries, why is there such a demand for coal? In spite of these issues,coal is a critically
important resource. This is due to four major factors:(1) the relative ease and low cost with
which coal may be mined and transported (and these costs are even lower when externalities are
ignored),(2) the energy readily made available when coal is burned,(3) the lack, or
nonenforcement,of environmental laws in many developing countries, and (4) the strides made in
most industrialized countries to improve mine safety and control certain coal emissions.
GLOBAL COAL USE Figure2shows global coal consumption. According to oil giant BP,coal
accounts for onefourth of global energy. FIGURE 2 Global coal consumption(World Coal
Institute,www.worldcoal.org). Question 10: Which four countries account for most coal use
worldwide? Figure3shows global recoverable coal reserves, Question 11: The United States' total
coal production is approximately 1,100 million short tonnes annually. 2 How many years supply
at this rate will domestic supplies last? Question 12: Chinese annual coal use is about 1.5 billion
metric tons a year. How many years at this rate will domestic supplies last? FIGURE 3 Global
recoverable coal reserves(Stuart Staniford,The Oil Drum, as compiled from the 2005 BP
Statistical Report on Energy). Question 13: Naturalist and writer Edward Abbey once said, "We
will run out of air before we run out of oil." His words are perhaps even more applicable to coal.
What do you think the quote means, as applied to coal? Question 14: How is increasing global
use of coal related to issues of sustainability?