COAL IS BURIED SUNSHINE
Coal, quite literally, is energy from the sun - energy that has been trapped and buried under pressure for millions of years within the earth.
More than 300 million years ago - during the Carboniferous Period - tropic-like forests of giant ferns and reeds covered vast areas of the earth. The climate was hot; the atmosphere, damp; and the terrain, swampy.
These giant plants stored up radiant energy from the sun. They lived, died and accumulated - layer on layer - in the surrounding swamp water. Here they decomposed and formed peat.
Slowly the surface of the earth changed. The seas advanced and receded in cycles, depositing on top of the accumulated peat heavy layers of material which became sandstone, shale and other rock. Thousands of heat and pressure cycles over millions of years compressed, dried and hardened the peat to form coal.
Peat - while essential to the development of coal - is not classified as a coal itself. The four classifications of coal are: lignite, subbituminous, bituminous and anthracite.
THERE ARE FOUR KINDS OF COAL
Lignite is the lowest classification of coal. Often called brown coal because of its color, lignite is the initial form of all higher grades of coal. It has a high moisture content, relatively low heat value and tends to disintegrate when exposed to weather.- Subbituminous has about half as much moisture as lignite, slightly higher heat value and weathering characteristics similar to lignite. Both lignite and subbituminous coal are used in some areas as fuels for the generation of electricity.
- Bituminous has a higher percentage of fixed carbon, less moisture, greater heat value and better weathering characteristics than lignite and subbituminous coals. It is the most useful and abundant kind of coal. According to geological estimates, seven feet or more of compacted plant life was required to form one foot of bituminous coal. All of the grades of coking coal used for metallurgical purposes fall within the bituminous classification. Most of the non metallurgical grades of bituminous coal are burned in boilers or furnaces to obtain thermal energy for generating electricity.
- Anthracite has a higher percentage of fixed carbon and a lower percentage of volatile matter* than all other coals. It was subjected to the highest pressures and temperatures, making it the hardest and highest carbon of all types of coals. While the use of anthracite as a fuel for heating has declined over the years, its high carbon and low sulfur content have increased its use for chemical and metallurgical purposes. (*Organic matter that is driven off as a gas when the coal is heated. Volatile matter and fixed carbon produce heat energy when coal is burned.)
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THE HISTORY OF COAL IN AMERICA
Although coal was known to the American Indians and to the early colonists, relatively little use of this fuel was made until the steam engine was developed in the late 1700s. Prior to that time, American heat and power came largely from firewood. The steam engine, however, required fuel that would burn longer than wood and give a more intense heat. Coal met those requirements.
A two-fold impetus to increase coal usage occurred in the mid-1800s: first, the expansion of America's railroad system, and, second, the growing use of coke in replacing charcoal and anthracite to make iron by America's emerging steel industry. The growing scarcity of wood was also a major factor in the switch to coal. About one acre of woodland was required in order to maintain one ton of annual iron production. Since then, rising demands for steel, industrial facilities, and electricity have vastly increased the demand for coal.
In those early times and until about the 1940s, coal was mined by pick and shovel. Miners worked in underground seams and dug the coal away from the walls with picks.
Coal mining has changed significantly since then. Today coal is mined safely and efficiently by skilled miners using modern machinery and methods. In addition to an ongoing Bethlehem safety program, state and federal agencies make routine inspections to insure that mandatory safety standards are followed.
In general, the coal miner in the United States produces more coal per day than does the average miner of any other country in the world. The amount of coal mined in a year in the United States (nearly 700 million tons) would fill a train long enough to reach around the earth three times at the equator. In fact, one of every six freight cars used by the railroad hauls coal.
Coal was the primary energy fuel for trains in the 1800s.
Nearly 70% of the coal produced in the United States is transported to customers in open-top rail cars called hopper cars.
COAL: AN ABUNDANT FUEL RESOURCE
At present, there are four fuels that provide most of the energy used in the United States: coal, oil, natural gas and uranium. Of these, our domestic supply of coal is by far the most abundant.
On a BTU basis, coal represents 82% of the nation’s proven reserves of all fuels and about 76% of their ultimately recoverable reserves. By contrast, proven reserves for oil are estimated to be 3%; 4% for natural gas; 4% for uranium (used to generate nuclear power); and 7% for oil shale.
According to the World Energy Conference Survey in 1977, the United States has the largest proven recoverable coal reserves in the world – about 31% of the world’s total. Russia has 23% and China about 13% of the worlds proven reserves.
Known or proven reserves in this country – reserves that can be recovered with present mining methods – amount to 218 billion tons. The nation’s ultimately recoverable reserves are estimated at 1.7 trillion tons. That is more than half of the 3.2 trillion tons of the total estimated coal reserves in the United States. Approximately one-eighth of the area of the United States is underlain by coal-bearing strata, and these strata are known to occur in 37 states.
In short, coal is available now and is more than sufficiently plentiful to meet growing energy demands for hundreds of years. Greater reliance on coal will allow us to develop the technology needed to install productive facilities to make a significant contribution to our energy supply.
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