If the gas is to be used for heating ovens or furnaces in connection with the generation of power, the character of the fuel will be determined to a great extent by the requirements of the ovens and by the type of producer used, as each fuel will give the gas certain properties. Thus gas used for firing crockery will not be suitable for use in open hearth steel furnaces, as the impurities in the various fuels may have an injurious effect on the manufactured product. The cost of the fuel, cost of transportation, heat value, purity, and ease of handling are all factors in the selection of a fuel.
The size and condition of a fuel is also of importance. Exceedingly large lumps and fine dust are both objectionable.
Wet fuel reduces the efficiency of the producer, as the water must be evaporated, this causing a serious heat loss.
With careful attention a producer gas engine will develop a horse-power hour on from 1 to 1¼ pounds of anthracite pea coal, and in many instances the consumption has been less than this figure. The efficiency in dropping from full load to half load varies by little, one test showing a consumption of 1.1 pounds of coal per horse-power hour at full load and 1.6 pounds of coal at half load. Producer gas power is nearly as cheap as water power, in fact the producer gas engine has displaced at least two water plants to the writer’s knowledge. According to an estimate made by a well known authority, Mr. Bingham, it is possible for a producer gas engine to generate power for only .1 of one cent more per K.W. hour than it is generated at Niagara Falls.
According to the United States Bureau of Mines,
“The tests in the gas producer have shown that many fuels of so low grade as to be practically valueless for steaming purposes, such as slack coal, bone coal and lignite, may be economically converted into producer gas and may thus generate sufficient power to render them of high commercial value.
“It is estimated that on an average each coal tested in the producer-gas plant developed two and one-half times the power that it would develop in the ordinary steam-boiler plant.
“It was found that the low-grade lignite of North Dakota developed as much power when converted into producer gas as did the best West Virginia bituminous coals burned under the steam boiler.
“Investigations into the waste of coal in mining have shown that it probably aggregates 250,000,000 to 300,000,000 tons yearly, of which at least one-half might be saved. It has been demonstrated that the low-grade coals, high in sulphur and ash, now left underground, can be used economically in the gas producer for the ultimate production of power, heat and light, and should, therefore, be mined at the same time as the high-grade coal.
“As a smoke preventer, the gas producer is one of the most efficient devices on the market, and furthermore, it reduces the fuel consumption not 10 to 15 per cent, as claimed for the ordinary smoke preventing device offered for use in steam plants, but 50 to 60 per cent.”