Mr. G. H. Morse1 has compiled some valuable statistics regarding the cost of developing power in this way, which are abstracted in TABLE No. 67. Owing to the uncertainty of the wind, it is necessary to provide a very large margin in the battery plant, or in times of calm weather there will not be a sufficient reserve. 714. The Actual Cost of Electrical Energy. - Whether for the design of a new plant, or as a guide in the operation of an existing installation, data as to present operating costs of representative electrical plants are of the utmost value to the engineer. A collection of the best existing information has been made of practice both in this country and Europe, and will be found in TABLES Nos. 68 to 73 inclusive. TABLE NO. 68 is given by Mr. Crompton,2 and contains the actual cost of producing electricity in twenty-three of the best English plants. The costs are itemized into "Fuel," "Stores," and "Labor," thus giving a very complete sub-division of the subject. For an ideal station, yet one within the limits of present engineering skill, Mr. Crompton estimates a capital of $2,500,000 to be required for an output of 5,000,000 K. I. per annum, and that it is possible to bring the cost of production only to about 1 cent per K. W. hour. In this table there are no allowances for interest, depreciation, taxes, and management; allowing 14 cents for these items, and cent for profit, it is calculated that, under the favorable conditions of a very large plant continuously operated, electricity could be sold at a profit at 1 See Year Book Soc. Eng., University of Minnesota, 1894. Cost per kilowatt hour in cents, distributed 5.70 5.18 6.85 5.02 4.54 6.65 Mean selling price in cents per kilowatt hour, including all expenses Charge without deduction for the kilowatt hour, in cents Price per cubic foot of gas, consumption above 3,000 cubic feet, cents .11 .12 .105 .103 .081 Industrial efficiency of the accumulators, per cent Energy furnished by the discharge, in kilowatt hours 59,573 194,733 279,506 42,584 per cent Ratio of energy supplied by the accumulators to the total energy distributed, Loss in the accumulators, per cent of the total energy distributed 154,836 216,561 71.5 79.4 77.5 3 cents per K. W. hour. Present practice indicates that on the average the selling price must be about double this figure. 715. There is no doubt that improved machinery, better engineering, and a more thorough study of electrical science, are constantly tending to reduce the cost of production. This is exemplified in TABLE No. 69, collected from data given by Mr. Stevens.1 Here a comparison is given between the cost of production at six of the large English stations for the past three years. On an average, there has been a decrease of about 30 per cent in actual cost. From these figures it seems not impossible that Mr. Crompton's expectations may be realized. 716. In the Electro-technische Zeitschrift, Max Meyer1 gives an article on the operating expenses of a number of the largest stations on the Continent, from which TABLE NO. 70 is epitomized. The costs here are in the neighborhood of 5 cents per K. W. hour. In TABLE NO. 71 is a comparison of operating expenses of a large number of central stations made by H. A. Foster.2 As the data are derived from fifty-four plants, the averages would seem to be exceedingly trustworthy. The cost of production from these figures is seen to be about 5.4 cents per K. W. hour. In the same article, Mr. Foster has made a very extensive collection of data from information obtained from a hundred and fifty lighting-stations in this country. As the range of the inquiries is very broad, TABLE NO. 72 has been compiled from this source, embracing the figures thus obtained from actual practice as to the cost of installation and operation of lightingplants. The cost of plant per K. W. includes buildings and real estate, whenever owned by the operating company, and also the cost of the circuits. On the whole, the costs per K. W. hour are higher than those from European stations, but it must be remembered that the foreign data are taken from very large plants under continued operation. To select from TABLE NO. 72 stations of similar size will show a close agreement in operating costs. 717. In the Review of Reviews, February, 1893, Mr. R. J. Finley discusses "American Street Lighting," giving considerable data regarding the cost of plant and operation of municipal stations, in contrast with those of private ownership. The motive-power is not stated, an omission greatly detracting from the value of any compari1 See Electrical World, vol. xxiv., p. 206. 2 Electrical Engineer, vol. xviii, p. 188. sons that may be instituted. A summary of the data is to be found in TABLE NO. 73. All the figures apply to the operation of nominal 2,000 c.p. arc lamps. 718. Commercial Consideration of Transmission Problems. Every long-distance installation, from a constructive standpoint, must be regarded as made up of three factors. First. A generating-station, including prime movers for utilizing the source of energy, and dynamo machinery for transforming mechanical energy into electrical energy at proper potentials for economical transmission. Second. The necessary line for transferring this energy from the generating-station to the receiving-station. Third. The receiving-station, embracing such dynamo machinery as is necessary to reduce the high potentials used in the line to convenient voltage for distribution and use by customers. The vital consideration in all such installations then becomes the cost of energy delivered at the receiving-station by the transmission |
