Popular Science Monthly/Volume 52/April 1898/The Electric Transmission of Water Power
|THE ELECTRIC TRANSMISSION OF WATER POWER.|
EVER since the electric light and power industry began to be a factor in the economic affairs of the industrial world, its adaptation to the work of transmitting the power of waterfalls to more or less distant points has been the dream of those who realize its vast possibilities, and who believe that the ingenuity of man is equal to the task of overcoming any difficulties that may be encountered in attempts to find a successful solution of the problem. For more than twenty years those who may be called electrical enthusiasts have prophesied that the day would come when the power of Niagara would be delivered at the door of the consumer in the city of New York, and capitalists have not been lacking who would have provided the means for carrying out an undertaking of this kind if they had been given the proper assurance by electrical engineers of prominence that the results sought for could be attained. Such assurance, however, could not be given; for, although it is known that there is no difficulty in the way of accomplishing such a result theoretically, the practical development of the art has not reached a stage that would render the realization of such an undertaking possible.To transmit power by means of electric currents over long distances, without suffering too great a loss in overcoming the resistance of the conducting wires, it is necessary to make use of a high electrical pressure, the effect of which is to render very difficult the perfect insulation of the line, so as to prevent the escape of the current. The greater the distance to which the current is transmitted, the greater must the pressure be to keep the loss of energy and the cost of wire within permissible limits; hence, when the pressure
Although the achievement of such stupendous results as the transmission of power over several hundred miles is not within our present reach, it is possible to bridge distances of twenty or thirty miles, and the accomplishment of this much has been considered entirely practicable for several years. It was on this account that the Niagara power plant was started, the object being to supply the city of Buffalo and other places within a radius of twenty-five or thirty miles. This undertaking, owing to the magnitude of the power available, has attracted world-wide attention, and is probably regarded by the vast majority of people as the only work of any importance in this line that has been attempted. This, however, is far from being true; it is the largest, and will undoubtedly always remain such, since the source of energy is practically unlimited, but there are several other very large installations, and in some of these the distance of transmission from a mile or so up to thirty-five miles, place being nearly double that distance.
A fair idea of the extent to which this branch of the electrical industry has been developed may be gained from a consideration of the fact that one manufacturing concern alone has sold over two hundred thousand horse power of machinery for this purpose within the last four or five years, their sales for 1896 being over seventy-five thousand horse power. The great increase in the business during the past year, in the face of a general stagnation in all other lines of industry, is a very clear indication that what has been done in the past has been entirely successful—so much so as to inspire an amount of confidence sufficient to overcome the apathy or unwillingness to embark in new undertakings so manifest in all other lines of business.The total number of water-power transmission plants in successful operation in the United States in addition to the Niagara installation is over two hundred. The amount of power transmitted ranges from less than one hundred horse power up to twelve thousand, and the distance of transmission from a mile or so up to thirty-five miles.
There is one at Springfield, Massachusetts, where about nine hundred horse power is transmitted to a distance of over six and a half miles; one at Bondsville, Massachusetts, having a capacity of about thirteen hundred horse power; and another at Fitchburg, Massachusetts, of about four hundred horse power. In this latter plant the distance of transmission is only two and a half miles, but as an offset to it, in distance as well as amount of power, may be mentioned a plant in Quebec, Canada, where over two thousand horse power is transmitted eight miles. At Concord, New Hampshire, there is an installation of several thousand horse power capacity, which is transmitted to a distance of five miles.
At Hartford, Connecticut, there is a plant of about fifteen hundred horse power, which is transmitted a distance of eleven miles; at Baltic, Connecticut, about fourteen hundred horse power, and in several places in the New England States, installations ranging from two hundred to one thousand horse power can be found. At Hookset, New Hampshire, there is a plant of three thousand horse power, which is transmitted about eleven miles. In the State of New York there are plants at Gouverneur, Canandaigua, Tonawanda, and many other places.
The plant at Baltic, Connecticut, furnishes power to operate one of the Ponemah mills at Taftville, about four miles and a half distant. The interior of this mill is shown in the illustration on page 731. In addition to operating this mill it furnishes power to run the Norwich street railway.
The Ponemah mills, two in number, were originally operated by three turbine wheels and two steam engines, the water power not being sufficient at all times of the year to meet the requirements. In 1892 the Norwich Street Railway Company was changed from horse to electric, and made a contract with the Ponemah Company to furnish the power. The road, which started in a small way, soon increased, and the extra load proved too much for the three turbines and the two engines, located at the mills, to carry. It was then decided to develop and utilize the water-power privileges owned by the Ponemah Company some distance up the Shetucket River, and transmit it by means of electricity to the mills and the railway. The old dam was enlarged, and three turbine wheels, having a combined capacity of nearly two thousand horse power, were installed. These are belted to a line shaft from which the electric generators are driven. At the end of the line the current is used to operate one of the mills, to furnish the necessary light, and to operate the railway already referred to, and, in addition to this, two locomotives used to haul freight, one being of five hundred horse power and weighing thirty tons.
The current generated at the power station is of the alternating type, and undergoes one or two transformations before being used at its destination, but the operation of the apparatus is so perfect that this power, generated four and a half miles distant, can be used in connection with the steam engines at the mills, and each one will do its proper share of the work.
A plant of twelve thousand horse power is now being built at the Lachine Rapids, about five miles from Montreal, Canada, and, although it is not larger than some of those in operation, or in process of construction in the western part of the country, it may in time become such, as the source of power is very great, and increases can be made as fast as the demand calls for them. At Trenton, Canada, there is a plant of about nine hundred horse power which is transmitted a distance of twelve miles.
Within the past few months it has been found by the investigations of engineers that a very large power can be obtained near the town of Massena, in the State of New York. At this point the St. Lawrence River descends about one hundred feet in a few miles, going over the Long Sault Rapids; but the Grass River, which runs nearly parallel with it and only about three miles distant, drops but fifty feet. As a result of this difference in the fall of the two rivers, the St. Lawrence is fifty feet higher at the head of the rapids than the Grass. By cutting a canal of sufficient size at this point the water of the St. Lawrence can be diverted to the Grass and over the fifty-foot fall, thus developing an amount of power limited only by the size of the canal. The estimates of the engineers who have surveyed the site is that as much as two hundred thousand horse power can be obtained. The work of development is under way, and if it is carried through on the scale proposed will only be surpassed in magnitude by the Niagara plant.
The largest water-power transmission in the South is probably one located at Pelzer, North Carolina. At this place nearly four thousand horse power is utilized, and transmitted a distance of about three miles, where it is used for the operation of extensive cotton mills.
There are many transmission plants in different parts of the West, the largest of which is, perhaps, at Minneapolis, where the amount of power utilized is over ten thousand horse power; but none of these is of as much interest as those to be found on the Pacific slope, owing to the fact that with few exceptions the distance of transmission is short. In the latter section, however, the possibility of using electric transmission for great distances is better demonstrated than anywhere else. At Redlands, California, there is a plant that delivers the power at a distance of over twenty miles. At Fresno, California, over two thousand horse power is transmitted about thirty-five miles. A noticeable feature of this last-named installation is the enormous height of the water fall. The head is fourteen hundred and ten feet, which is the greatest in use, commercially, in any part of the world. What such a head really means can be realized when we state that the pressure of the water amounts to over six hundred pounds to the square inch. The distance of transmission, thirty-five miles, is also the longest now in actual use, but it is less than that of the Pioneer Electric Company of Ogden, Utah, which is in process of construction. The work now under way at this latter place will transmit power to Salt Lake City, a distance of thirty-six miles, but it is intended to carry the line to mines thirty miles beyond this point; therefore, when the whole system is completed, the total distance of transmission will be sixty-six miles.
The Folsom-Sacramento power-transmission plant is one of the most noteworthy of those so far installed, as it serves to show clearly the great benefits derivable from the use of electricity. The power station is located at Folsom, on the American River, where one of the largest water powers in the State of California is available. The first attempt to utilize this power was made as far back as 1866, but owing to the conditions then existing was necessarily limited in its capacity to the demands of the immediate vicinity. The work as at first conceived embraced a dam across the river, the water to be used in part for power and in part for irrigation purposes. The plan was modest in its proportions, and remained so for many years; but the development of electric transmission has magnified it into an undertaking of vast magnitude, embracing the development and transmission of over five thousand horse power when the full capacity is reached. The dam now used is six hundred and fifty feet long and eighty-nine feet high, and has a storage capacity of about thirteen million cubic yards. The water is conveyed to the water wheels by canals two miles long and fifty feet wide by eight feet deep.The power station in which the wheels and the electric generators are located is so designed that the latter are connected direct with the former, being mounted upon the same shafts, but separated from each other by a stone wall, through which the shafts pass. The electric current developed in this station is transmitted to Sacramento, a distance of about twenty-five miles, and is there received in a substation, the interior of which is shown on page 733. The current coming into this station from the power plant is of a very high pressure, entirely too high for commercial use, and
therefore has to be reduced by being passed through the machines shown in the illustration, which are called step-down transformers, their office being to reduce the pressure of the current. These transformers in reality do not reduce the pressure of the current; what they do is to generate a second current, by the aid of the energy derived from the first, of a much lower pressure. The power of the substation is to be used for all purposes, for "arc" and incandescent lighting, for driving stationary motors, and for the operation of electric railways.
The Big Cottonwood Power Company has about completed the construction of an important plant to utilize the water power of the lakes in the Wahsatch Mountains, and distribute it in and around the vicinity of Salt Lake City. These lakes, which empty into the Big Cottonwood Canon, lie at elevations above the sea ranging between eleven thousand and thirteen thousand feet; therefore the total amount of power available is very large on account of the enormous fall. The Big Cottonwood Company controls a fall of about one thousand feet, but in the present installation will only use about four hundred feet. The water is confined in a reservoir, as shown in the topographical map on page 737, and is conveyed by pipe line to the power house, as is shown quite clearly in the illustration of the site of the latter on page 739, where the pipe is seen in the background, descending between the mountains. To guard against an accidental giving way of the reservoir, as well as to render it possible to empty it when desired without interfering with the operation of the plant, the pipe line is carried along the bottom to the upper end of the reservoir, where it connects with the main source of supply. By closing one gate and opening another, the water may be drawn from either point, as occasion may require.The capacity of this plant is about twenty-five hundred horse power, which will be distributed at a distance of about fourteen miles. The water wheels are mounted directly upon the shafts of the electric generators, as can be seen from the illustration of the interior of the power station shown on page 741. The generator in the foreground is not provided with a water wheel; the only part of this apparatus visible is the water pipe under the shaft, between the two bearings. This generator was not completely mounted when the photograph was taken, but the two machines in the background, it will be noticed, are provided with water wheels, which are mounted on the shaft in the space between the two bearings, which in the front generator is uncovered. The simplicity and solidity of this apparatus are very striking, and, being one of the latest installations, show clearly the perfection to which machinery of this class has been carried; and from the fact that the capacity of
each generator is about six hundred horse power, its compactness is also apparent.
There are any number of other power-transmission plants in this country, a description of which would prove interesting not only on account of their magnitude, or the distance to which the power is conveyed, but also on account of their revealing the vast amount of engineering skill displayed in surmounting difficulties that have been contended with; but the examples described in the foregoing are sufficient to show the enormous strides that are being made in this field, and yet the general public is almost wholly unaware that anything is being done except in an experimental way.
The electric transmission of power is not confined to this country by any means; plants of very large proportions can be found in almost every quarter of the civilized world, and in some places not specially noted for their civilization. In Mexico there are several installations, and no doubt there would be more if it were not for the fact that there is a scarcity of large streams and rivers in that country; therefore, although its mountainous conformation would lead to the conclusion that waterfalls are numerous, as a matter of fact those where the power available is sufficient to warrant its utilization are very few.
The principal installation in Mexico is at Pachuca, one of the most important mining districts in the country. The power plant is located at Regla, which is about twenty-three miles distant. The capacity of the plant is over three thousand horse power.
There are several plants in South American countries, quite a number in Africa, in Australia, in Asiatic countries, and also in Europe. The Jungfrau Mountain Railroad in Switzerland, which has been called the trolley to heaven, will be operated by power derived from the Black and White Lutschine Rivers, in Burglauenen and Lauterbrunnen. This road, which is about finished, ascends to one of the highest peaks of the Alps, one which heretofore has only been accessible to those of sufficiently vigorous constitutions to make the ascent on foot.
The Geneva water power is utilized to operate electric railways, electric lights, and to some extent for the development of power for industrial purposes. The distance of transmission at this place is about twenty miles.
Other installations in Europe of importance that may be mentioned are Rome, Italy—distance, about eighteen miles; amount of power, two thousand horse power, which is being increased to nine thousand; Davos, Switzerland; Schongeisung, Germany; Lauffen to Heilbronn, Germany; Zurich, Switzerland, and many others.
The longest transmission ever undertaken was an experimental one between Lauffen and Frankfort, during the exposition at the latter place some years ago. This distance is one hundred miles, and, although the work was experimental and only intended to show what could be done, it was entirely successful, notwithstanding that the amount of power transmitted was only three hundred horse power.
From the few examples given in the foregoing paragraphs it can be seen that the electrical transmission of water powers to points where they can be conveniently utilized has passed far beyond the
experimental stage, and that the business of supplying apparatus for such purposes has already assumed large proportions, with every prospect that before long it will be a very important, if not the most important, branch of the electrical industry.
A contemplation of the results that may follow development along this line must lead to the conclusion that manufacturing centers will be materially changed. In many kinds of industry power is used so extensively that its cost is an item of the greatest importance, and concerns engaged in work of that class will in many instances find it to their interest to locate where the energy of waterfalls may be available at low rates. The successful operation of the Niagara plant has had the effect of attracting to that section of the State several enterprises that require power in large quantities, and it is more than probable that, before many years pass by, Buffalo and the surrounding country will become an important manufacturing center. What is true of this case will be equally true of many others, and, while established enterprises may not remove from their present location, those started hereafter will undoubtedly be guided by the relative cost of power at different points, in connection with the advantages and disadvantages arising from the location of the power center. Thus, as the South is the source whence all the cotton comes, it would be natural to assume that manufactories in this line would locate in that section at points where water power can be obtained convenient to the cotton fields. That such localities can be found is quite evident, since, according to the census of 1880, the power available along the Chattanooga River is not far from one hundred thousand horse power, and along the various rivers of North and South Carolina, Georgia, and Alabama three or four times this amount can be obtained. All over the West and Northwest extensive power sites are to be found, and in time many of them will be rendered useful, and will form the centers of manufacturing districts, thus gradually augmenting this line of industry in sections of the country that at present are principally agricultural.
For several years to come it is very probable that efforts will be confined to the utilization of large units, but gradually the cost of installation and of operation will be reduced, and then smaller powers will be considered profitable. Following along this course of reasoning we may naturally conclude that, eventually, even farmers may be able to render available the energy of small streams passing through their possessions, and the future rural generations may use the electric motor to do the work around the farm that at the present time is performed by animal power.
- For the illustrations in this article we are indebted to the kindness of the General Electric Company.