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Indiana University Studies 



than steam units, the cost of power in the small oil-driven plant 

 now in use in one of the small stone mills is interesting. The 

 engine as before stated is a 40 horse-power Fairbanks-Morse 

 engine, and, according to the owners, cost approximately $1,400 

 installed. The fuel used cost 7}^ cents per gallon, and the con- 

 sumption was about 113/2 gallons per day of 10 hours. The cost 

 of power on such a basis is as follows: 



Fixed charges — 



Interest at 5 per cent $70 . 00 



Depreciation at 8 per cent 112.00 



Insurance and taxes at 2 per cent 28 . 00 



Total fixed charges $210 . 00 



Operating costs — 



Cost of fuel at 73^ cents per gallon, 113^ gallons per 



day, 200 days per year $172 . 50 



Repairs, 3 per cent on investment 42 . 00 



Supplies 25.00 



Labor of one man, part-time office work 100 . 00 



Total operating cost $339 . 50 



Total power cost $549 . 50 



A 50 per cent load factor for 200 days of 10 hours each gives 



40,000 horse-power hours, or a cost of 1.37 cents per horse-power 

 per hour. This is about 1.7 cents per kilowatt hour. 



These figures compare favorabty with figures given on a 

 20-kilowatt oil plant by R. L. Streeter in the Factory Magazine 

 where the total cost of the installation was given as $2,200 

 and total power cost as $973, giving a cost of 2.1 cents per kilowatt 

 hour. 



The same authority gives the cost of a 100-kilowatt plant as 

 $13,100, with total power cost as $3,810 or a cost of 1.69 cents per 

 kilowatt hour. 



Many of the plants are growing in size, and as the machinery 

 in use at the present time gives out, the owners are casting about 

 to determine the approximate cost of power with a larger plant 

 or trying to determine when the saving will justify scrapping 

 the machinery now in use. For this reason I will try to outline 

 roughly the cost of power plants of 250 and 500 kilowatt capacities. 



A 250-kilowatt oil engine plant can be installed for approxi- 

 mately $31,000 with a total power cost of $7,000 per year, or 

 about 1.6 cents per kilowatt hour. 



