| Steam Power. | Gas Power. | |||
| British thermal units. | Per cent. | British thermal units. | Per cent. | |
| Losses in exhaust, friction, etc. | 11,892 | 95.14 | 10,812 | 86.5 |
| Converted into electric energy | 608 | 4.86 | 1,688 | 13.5 |
12,500 | 100.00 | 12,500 | 100.0 | |
The ratios of the total fuel per brake-horsepower hour required by the steam plant and producer-gas plant, under full load, not counting stand-by losses, are presented below as derived from 75 coals, 6 lignites, and 1 peat (Florida).
The curves in Figure 3 show graphically the great economy secured with the producer-gas plant. The figures
for the producer-gas tests include not only the coal consumed in the gas producer, but also the coal used in the auxiliary boiler for generating the steam necessary for the pressure blast—that is, the figures given include the total coal required by the producer-gas plant.
Ratios of fuel used in steam and gas plants.
| Average ratio, coal as fired per brake-horsepower hour under boiler to coal as fired per brake-horsepower hour in producer | 2.7 |
| Maximum ratio, coal as fired per brake-horsepower hour under boiler to coal as fired per brake-horsepower hour in producer | 3.7 |
| Minimum ratio, coal as fired per brake-horsepower hour under boiler to coal as fired per brake-horsepower hour in producer | 1.8 |
| Average ratio, lignite and subbituminous coal as fired per brake-horsepower hour under boiler to lignite as fired per brake-horsepower hour in producer | 2.7 |
| Maximum ratio, lignite and subbituminous coal as fired per brake-horsepower hour under boiler to lignite as fired per brake-horsepower hour in producer | 2.9 |
| Minimum ratio, lignite and subbituminous coal as fired per brake-horsepower hour under boiler to lignite as fired per brake-horsepower hour in producer | 2.2 |
| Average ratio, peat as fired per brake-horsepower hour under boiler to peat as fired per brake-horsepower hour in producer | 2.3 |
In considering the possible increase in efficiency of the steam tests with a compound engine, as compared with the simple engine used, the fact should not be overlooked that a corresponding increase in the efficiency of the producer-gas tests may be brought about under corresponding favorable conditions. Not only is the producer passing through a transitional period, but the gas engine must still be regarded in the same light. In the larger sizes the vertical single-acting engine is being replaced by the horizontal double-acting engine. Other changes and improvements are constantly being made which tend to increase the efficiency of the gas engine, as compounding and tripling the expansions have already increased the efficiency of the steam engine.
As has already been stated, the gas engine used in the tests here reported is of a type that is rapidly becoming obsolete for this size, namely, the vertical, three-cylinder, single-acting.
A brief consideration of these points will lead at once to the conclusions that a comparison of the producer-gas plant and steam plant used in these tests is very favorable to the former, and that any increase in efficiency in the steam tests that might result from using a compound engine can be offset by the introduction of a gas engine of more modern type and a producer plant designed to handle the special kinds of fuel used.
