The Economic Aspect of Geology

by C. K. Leith

CONSERVATION OF COAL

In the sections on mineral resources, there are many casual references to conservation of specific minerals. Here we shall not go further than to introduce a brief discussion of the conservation of coal as illustrative of the general problem of conservation of mineral resources.

It has been estimated that the United States possesses, to a depth of 3,000 feet, in beds 14 inches or over, 3,538,554,000,000 tons of coal, and an additional reserve between 3,000 and 6,000 feet of 666,600,000,000 tons.[42] If all the unmined coal to a depth of 3,000 feet could be placed in one great cubic pile, the pile would be 18 miles long, 18 miles wide, and 18 miles high. Of the original amount of coal to this depth only about 0.4 of 1 per cent has been mined or wasted in mining. The wastage is estimated at about 50 per cent. If the annual production of coal were to remain the same as in recent years, the total life of the coal reserves (to a depth of 3,000 feet) would be between 4,000 and 6,000 years; but if the acceleration of production of recent years were to be maintained in the future, the life would be but little over 100 years, and the life of the highest-grade coal now being mined might not be over 50 years. All agree that the acceleration of production is not likely to continue indefinitely, which will mean that the life of coal reserves to 3,000 feet will be somewhere between the two extremes named. It seems clear that actual shortage of coal will not be felt for some hundreds of years; but this period of years is short as compared with the probable life of the race.

Measures Introduced or Proposed to Conserve Coal

The following list of measures for conservation of coal is taken from several sources. The exhaustive report of the British Coal Commission,[43] published in 1905, contains a considerable number of specific recommendations for conservation of the coal of Great Britain. The reports of the National Conservation Commission[44] of the United States, published in 1909, treat of the conservation of the coal of the United States and naturally follow some of the recommendations of the British report. The coal section of the National Conservation report was prepared by M. R. Campbell and E. W. Parker of the U. S. Geological Survey, and is contained in U. S. Geological Survey Bulletin 394. The recommendations there given are amplified and developed by Van Hise[45] in his book on Conservation, published in 1910. Since that time the subject has been discussed by Smith, Chance, Burrows, Haas,[46] and others, and certain additional conservational methods have been proposed. A considerable number of men have also discussed the sociologic and economic aspects of the question. The report of the Conservation Commission of Canada,[47] published in 1915, treats rather fully of the conservation of mineral resources.

It will suit our purpose, and avoid some repetition, if we group most of these recommendations without regard to authorship. In general, these recommendations can be grouped under the heads: (A) Methods of mining and preparation of coal; (B) Improvement of labor and living conditions at the mines; (C) Introduction or modification of laws to regulate or to remove certain restrictions on the coal industry; (D) Distribution and transportation of coal; (E) Utilization of coal; (F) Substitutes for coal as a source of power.

(A) Mining and preparation of coal. Under this heading may be included a large number of proposals which concern primarily the engineering treatment of the coal underground and in the mine plants. Some of the more important measures are:

1. Introduction of the long-wall system of mining in places where the conditions allow it, in order to minimize the waste underground.

2. Modification of the room-and-pillar system of mining, by which larger pillars are left while the mine advances, and are recovered in the retreat,—thereby recovering a larger percentage of coal than under the old system, where small, thin pillars were left, which failed and were permanently lost.

It has been argued that the great loss of coal by leaving it in pillars could be saved by using other material to support the roof; but an elementary calculation of the cost of this procedure shows that it is cheaper to use the coal. Chance[48] says: