BY ROBERT HEYWOOD FERNALD.
[Professor of Mechanical Engineering, Case School of Applied Science.]
Official reports show that the coal placed on the market amounts annually to between 450,000,000 and 500,000,000 short tons in the United States alone. These figures, however, are somewhat misleading as they do not in any way show the tremendous wastes that are going on due to our present methods of mining and restrictions in qualities of coal that can be transported and placed on the market at a reasonable profit. Careful investigation has shown that the coal wasted or left in the mines in such form as to be inaccessible to future generations amounts each year to practically 100 per cent of that placed on the market, or in other words, at the present time some 450,000,000 tons are annually lost as far as commercial value is concerned.
If this condition is allowed to continue it is estimated by the United States Geological Survey that our available supply of bituminous coal will be exhausted within the next two hundred years.
A realization of the seriousness of this situation has led to a careful and systematic study of the present lack of efficiency in the utilization of fuels for both power and metallurgical purposes, to investigations into more efficient use of the present marketable grades of fuel, and to a consideration of methods of using the so-called low-grade fuels, lignites and peats.
The United States Geological Survey has for several years been investigating the economic value of coals and lignites as gas-producer fuel. This work, begun with tests
of coal and lignite at the coal-testing plant erected at the Louisiana Purchase Exposition, St. Louis, Mo., in 1904, was continued at St. Louis and at Norfolk, Va., and is now being carried on by the Survey at the fuel-testing plant in Pittsburg, Pa. The tests were undertaken because it was evidently desirable to determine the value of the gas producer as a means of increasing efficiency in the use of the coal supplies of the United States. The early tests proved decidedly encouraging, demonstrating that many coals now wasted or not mined because they are not satisfactory fuel for steam-power plants can, by conversion into producer-gas, be made to do from two to three times as much work as can be done by the best grades of steam coal burned in a boiler plant. In consequence, the making of producer-gas tests and the study of the processes that take place within the gas producer now form an essential part of the fuel investigations conducted at the Pittsburg plant under the provisions made by Congress for the analyzing and testing of mineral fuels.
Rapid Development of the Gas Engine.
It was not until late in the nineteenth century that the gas engine came into common use, and although many types have been devised within the last twenty or thirty years it is only within eight or nine years that large gas engines have been constructed. This development started eleven or twelve years ago in Germany, Belgium, and England, but marked progress has been limited to the last eight years.
For a long time the natural fuel of these internal-combustion engines was city gas, but this was too expensive except for engines of small capacity. It was seldom found economical to operate units of more than 75 horsepower with this fuel. Cheap gas was essential for the development of the gas engine, but the early attempts to produce cheap gas were somewhat discouraging, and for a