8 BULLETIN 1203, U. S. DEPARTMENT OE AGRICULTURE. 
.V general comparison can be made with the cost of the ordinary 
fuels with which t lie straw gas produced in this plant would have to 
compete. The number of British thermal units per unit for each fuel 
Or source of energy considered forms the basis of comparison. The 
approximate heating value (in British thermal units) of straw gas 
is considered to be 400 per cubic foot; that of gasoline, 108.000 per 
gallon; that of kerosene, 128,000 per gallon: that of anthracite 
coal. 15,100 per pound of combustible, or 12,250 per pound of coal; 
that of bituminous coal (high grade), 15,200 per pound of com- 
bustible, or 13,600 per pound of coal; that of wood (air dried), 
6,000 per pound: and that of electricity. 3,415 per kilowatt hour. 
On the basis of heating units produced, straw gas, as a fuel for 
heating, cooking, and stationary power purposes, costs at least 1 
cent per 1,690 British thermal units. 6 Wood selling for $10 a cord, 
sawed and split, costs 1 cent per 18,000 British thermal units: anthra- 
cite coal at $15 a short ton costs 1 cent per 16.335 British thermal 
units; bituminous coal (high grade) at $14 a short ton costs 1 cent 
per 19.430 British thermal units: gasoline at 25 cents a gallon costs 
1 cent per 4,320 British thermal units ; and kerosene at 18 cents a gal- 
lon costs 1 cent per 7,110 British thermal units. 
When wood and coal are burned for home-heating purposes a large 
quantity of heat is lost and wasted. It has been estimated that in the 
neighborhood of 30 per cent of the heating units pass up the chimney 
with the flue gases. The aggregate loss is still greater when these 
fuels are used for cooking jutrposes, since much heat is also wasted 
during the preparation of a hot fire and after the completion of the 
cooking. These losses do not occur when gas is burned. Considering 
these heat losses, wood selling ;it $10 per cord would cost 1 cent per 
12,600 British thermal units, anthracite coal at $15 a ton, 1 cent per 
11,435 British thermal units, and bituminous coal at $14 a ton, 1 cent 
per 13,600 British thermal units, when used for heating the home. 
These figures would be somewhat higher when these fuels were used 
for cooking purposes. The cost of straw gas produced in the experi- 
ment ;il plant, then, is very high as compared with the cost of ordi- 
nary fuel-. 
The cost of straw gas as a source of light for farms is about half 
again as great as that of electricity supplied by an individual electric 
lighting plant. Assuming the yearly consumption to be 432 kilowatt 
hours, the cost of electricity produced by a good farm electric plant 
of approximately out 1 kilowatt output for the average farm varies 
from $0.36 t<» $0.46 per kilowatt hour. 7 For the sake of comparison, 
a cost of $0.40 per kilowatt hour will be taken. When burned in an 
inverted gas-mantle lamp at the rate of 1 cubic feet per hour, straw 
gas produces a light of about 14.4 candlepower. Considering a 
tungsten incandescent (vacuum) electric lamp to average about 1 
candlepower f<»r each watt, and allowing appropriate charges for 
the necessary gas pipe and gas-lighting fixtures, straw gas would 
cost aboul 67 cents per l.ood candlepower hours, or 1 kilowatt hour. 
8 Round numbers are used in all these calculations. ^ , ^ 
■r ogle, F*. i ni.- Farm Electric riant. Michigan Agricultural College Quarterly 
BuUetin \ (1921), pp. 119-121. 
