HYDRO=ELECTRIC DEVELOPMENT.

Progress, Volume II, Issue 2, 1 December 1906, Page 64

HYDRO=ELECTRIC DEVELOPMENT.

By Fredk. Bf ack, A.M. Inst. E.E {Engineer, Wailn Water-Power Scheme)

PART 11. One of the most wide-spread views concerning hydro-electric power supply is that it must of necessity be cheap to the consumer, " because the water costs nothing." If a steam or gas-producer power station is installed to supply electricity, there is the monthly coal bill. How can any engineer justify the recommendation of a fuel-using plant if a -water power is anywhere withm transmission distance ? The hold that this fallacy has upon many intelligent people is little short of marvellous. It is a product of the popularisation of an intricate and difficult engineering subject, which forcibly appeals to the imagination of the public mmd by reason of the great results sought. It has always been an admirable thing for the progress of electrical engineering that the general public should have taken a keen interest in each notable step of its development — from telegraphy to lighting, from lighting to citypower supply and traction. Now public attention is directed to the electrification of great railway systems, and the transmission of power over wide areas of country. This interest has had a stimulating effect, both mentally and materially, thus giving to engineers higher imaginative power and the means with which to carry out big undertakings But whenever the public's ideas force the pace of development, disaster is certain to result This occurred in England m the early days of electric lighting, when the public demanded great undertakings all over the country, notwithstanding that the best technical opinion was adverse. The movement was years ahead of the times and of the state of electrical knowledge, and it ended in great failure, with much loss of capital, and a set-back to electrical development. The more alluring the possibilities, the greater is the risk of this expeuence being repeated, and I am satisfied, from personal discussion with numbers of business men in all parts of the colony, that there is a danger of hydroelectric development being seriously injured by the efforts of public opinion to employ it indiscriminately. Water does cost something It costs the whole of the capital charges upon the hydraulic works that harness it and make it available , it costs also the capital charges upon that proportion of the entire installation from turbines to selling end of transmission line — not mfrequentlv 15 or 20 per cent, of the whole — that does nothing but supply the energy dissipated in the unavoidable transmission loss. These capital charges, if the transmission is a long one, or the harnessing of the water difficult and costly, or for both reasons together, may be so heavy that the energy, when it reaches the market, has cost three or four times the money that it could have been obtained for, if generated locally from coal. Some months ago it was seriously suggested that the Huka Falls in the centre of the North Island should be harnessed and made to supply electricity to Auckland and Wellington. In an investigation that I was instructed to make of the proposal, the results of which have been published, I found that under the most favourable conditions — too favourable, in fact, to be obtained for several years to come — it would be impossible to deliver energy in Wellington in bulk for less than 6d. per horsepower hour. When retailed to the consumer the cost could not be much less than Bd. At the present moment the power user in the capital city, making his own energy from coal, often in a wretchedly uneconomical steam plant, does so for a total cost of rarely more than 3d., and if in a producer-gas plant, for id. ! Why should Huka power be so costly ? Because of the enormous cost of the water ; in other words, because capital charges would have to be paid every year on the cost of harnessing works, generating plant for supplying the energy expended in overcoming transmission line resistance, the transmission line itself, and a large amount of transforming plant — all of which sources of expense would be non-existent m the case of a steam or gas-producer installation The figures are worth a little consideration

To this annual cost must be added depreciation and maintenance, items which together would certainly not be less than 8 per cent., that is, Now we have the cost of the Huka water, viz., per annum Forty thousand pounds would buy a big lot of coal. After going to all this expense the hydro-electric energy would be landed in a city where coal of good quality is sold for 20s per ton, and where even an obsolete form of steam driven electric station offers energy to all and sundry at less than 3d. delivered. Quite recently the chief engineer of the Public Works Department,- Mr. P. S. Hay, M.1.C.E., has condemned the Huka Falls proposition, not, however, on the grounds of the excessive annual cost, but because of lack of sufficient water to furnish energy to all the chief markets of the North Island. It is significant of his sentiments that whereas he states that " Waikaremoana is the only scheme which could be considered m connection with any proposal to serve all the North Island from one power station," he does not recommend the Government to develop that power in lieu of the abandoned Huka. Everything I have said about Huka applies with equal or even greater force to Waikaremoana, which, according to Mr. Hay's valuable and interesting report on the colony's water powers, is much the better power of the two. In a word, the position of both Huka and Waikaremoana, far remote from markets, is fatal to their value. I have dealt with the case of the Huka Falls at this length because it is (or was) a specific proposition, and because also it forms a most effective illustration showing how enormous may be the cost of water to the owners of a hydro-electric transmission plant. The truth that this analysis drives home is that every hydro-electric scheme should be the subject of detailed investigation to ascertain the probable cost of the power it is to furnish by the time the consumer is reached, and that while such a scheme as the Huka one may be possibly the worst example of hydro-electric aberration in New Zealand, other propositions of lesser degree may be just as unsound commercially, because utterly incapable of meeting and overcoming competition from power derived from coal The capital cost of hydro-electric development cannot be stated in figures of general application Obviously, hydraulic works will vary enormously according to the physical surroundings. About the only constant feature they possess is great magnitude and if anyone doubts this let him turn to Mr Hay's report, already referred to, or look up the articles describing undertakings constructed during the last few years that have appeared in the technical press. A point generally overlooked is that hydraulic works are not a liquid form of asset. They cannot be transplanted if the undertaking of which they form part — usually the most expensive part — is not a financial success. Here is another important reason for exhaustively examining the prospects of every scheme The cost of turbines or, in the case of high falls, Pelton wheels, varies to a considerable degree, depending upon the volume of water to be dealt with m securing a given horse power. The greater the fall, the more substantial and massive must be the conduit line bringing the water from the intake to the penstock. In the majority of cases, the hydraulic works must be constructed, from the first, to the full size necessary for utilising the ultimate amount of power that will be required, as it is often impossible to only partially harness a river, and always much more costly to construct conduits or tunnels one after the other, as needed, than to make one of full size at the start of operations. The cost of dynamos and transformers per kilowatt is less variable than the other items, while that of the transmission line per mile is full of uncertainty until the route is surveyed and a contract made for the purchase of the copper. Here, however, is the summary of an estimate recently worked out for an undertaking to supply light and power to a city, it being clearly understood that the hydraulic-works cost is peculiar to this scheme and is absolutely no criterion for any other The power house is situated 17 miles from the city boundary the installation has to be capable of delivering 3000 h.p. to the low tension city mains, and the transmission line crosses open settled country, free from flood and landslide risks The amount of fall is 35 feet.

The two notable features in this are the low cost of the hydraulic works, due to natural suitability of the river, and the high cost of the transmission line, due to abnormal price of copper. In calculating what will be the cost of energy delivered to the consumer, it is necessary to first estimate the likely demand and its average daily character. For an industrial market of the best kind, the demand will be comparatively steady for 10 to 12 hours daily in the summer months, and for 1 2 to i s hours daily m winter, it bemg reasonable to assume that the great bulk of domestic and public lighting will be secured. A market of poor industrial character will rarely, if ever, justify a hydro-electric scheme, no matter how good the prospects of lighting may be, unless the hydraulic works can be of an extremely inexpensive character, and the transmission lme a short one. A market comprised almost entirely of electric railway supply is happily not common, for it is about the worst and most expensive of any to handle, except in cases where a frequent service of cars is run, and in this event it should — as already explained — soon become a mixed market. The actual duration and extent of demand can usually only be forecasted by a detailed investigation, including a thorough canvass of the district or districts affected ; and when this is done the personal equation still comes in, for experience, and what I can only term a trained intuition must be brought to bear upon the mathematical result. Having arrived at a conclusion, it is then comparatively a simple matter to divide the maximum supply capacity over a certain number of turbines and generators, and to fix the capacity of spare plant, it bemg of course necessary to include in the demand on the generators that amount of energy which is expended at time of full load in overcoming the resistance of the transmission line. The three great factors in determining the cost to the consumer are . First, ratio of normal load to maximum load in extent and duration , second, capital charges on the total cost of installation, and third, length of transmission lme. The importance of the first and second factors I have endeavoured to explain ; the third one is bound up with the other two as regards carrying capacity and cost, but calls for additional treatment on the score of absorption of energy. With any given size of line and given input of energy the greater the distance that energy is transmitted, the greater will b<= the transmission loss, and theiefore the smaller the output. The loss is a loss ot pressure (volts), not of quantity, just as water forced through a long length of pipe emerges with some loss of pressure (lbs. per sq. in.), but still the same quantity or number of gallons. No matter how great the pressure of input, some fraction must be absorbed in the lme by forcing over it the quantity originally put m and ultimately taken out. It is commonly spoken of as " transmission loss." but it is only a loss in the sense that it is expended in doing necessary work. Within the practicable variations of pressure it increases with the distance of transmission, proportionately increasing the cost of energy output, until a commercial limit is reached when that energy becomes too dear to compete with coal. It is this factor, which in conjunction with capital charges, kills more hydro-electric schemes at their first investigation than any other. A still further factor in determining the cost of supply is operating costs — wages, salaries, sundry materials, maintenance (including cost of patrolling line), and repairs. As a general rule, however, the influence of this item is small compared with the others mentioned, unlike the steam or gas power installation, where it is always a very material item. This being so, a detailed discussion of it may be omitted for the present, as being of more purely technical interest. The question of what constitutes a good enough market to justify a hydro-electric installation is not easily answered, yet it is the alpha and omega of the whole subject. Occasionally, as m the recent Horahora proposition of the Waihi Gold Mining Company, the market is a definitely assured one, and thus the commercial practicability of the scheme can soon be determined. But the average scheme is for a general public supply, the extent of which has to be estimated. All the qualities that make for shrewd business management with an up-to-date resourceful policy will have to be employed yet these will fail if the market is incapable of being made sufficiently large and progressive enough to give a return on the capital invested. Industrial towns are nearly always essential, but if they possess supplies of cheap coal they will not constitute a market, unless the hydro-electric plant can be economically installed within close reach. In New Zealand every town which runs a freezing works or can lay claim to having m its neighbourhcod a dozen or two flax mills or a few saw mills, and happens to be within a hundred miles of a water power, considers that it is entitled to the benefits of hydro-electric supply. The colony is not yet thickly populated enough to enable these small centres to exist m clusters. Unless, therefore, they

he upon or very near the route of a transmission line supplying one of the larger cities, they do not form adequate markets. In parts of Switzerland, where there is a waterfall of some size or other in nearly everyone's back yard, demands of this character may often be met, but until towns in this colony acquire the habit of forming themselves on the lower slopes of alps, it would be preposterous to attempt it here. The nearest approach to this that we have at present is the case of certain mining towns, and as the power requirements of these are usually considerable, they at least offer a promising field for close examination. The hard fact has got to be faced that, with occasional exceptions, the only possible markets of any value for hydro-electric energy are the cities, and some sections of the railways, while, most unfortunately, the majority of the practicable water powers are many leagues from anywhere — and good coal is only 15s. to 255. a ton in the heart of the market. To disregard this stubborn truth and expect power users to buy energy simply because it is hydro-electric energy, is foolish. Any glamour the water power may have will not last five seconds, if it turns a factory's monthly coal power bill from a sovereign into an electricity bill of a guinea, for the same output of wares. Ido not hesitate to say that the only alternative to this, m many of the hydro-electric schemes now proposed, involving long transmission distances, is to sell the energy below cost pricevery much below in most cases. If undertakings are to be run without becoming a direct burden on the general body of tax-payers (assuming there to be state ownership), long distance transmissions are inadmissable m New Zealand A 200-mile proposition might just as well be a 200,000 mile one— to the moon. There would be about as much supply done from the one as from the other Finally, a word may be said as to the possibility of taking Mahomet to the mountain, when it costs too much to take the mountain to him. Can the market be taken to the water power > I see no possibility of doing so, but by the ordinary development of the country m population and industries If the raw materials of manufacture can be obtained cheaply near the water power, and the cost of transport of the finished articles to their market is not excessive, the market may eventually go to the water power. It is a moral certainty that the manufacturing interests of the existing cities cannot be transplanted from the sea-board to far inland sites all in a hurry , I, for one, do not think they will ever be transplanted, though it is reasonable to suppose that m course of years, as the country becomes more and more developed, and coal perhaps becomes a little more expensive, and city expenses heavier, that industrial development will gravitate inland. When that day arrives, the Huka Falls and Waikaremoana may come into their glory — but it is not yet.

While some people were dining at a Wmchebtei (Eng ) hotel a salmon was put on the table and it was found to possess two distinct backbones joined at the tail.

Capital Cost for io.ooo h p Hydraulic works . . . . . . Generating plant supplying transmission losses . . 25 000 Transmission line .. . .. 150,000 Transformers . . . . . . . 35,000 ipital charges at 5 % per annum . . /i 5,500

iydrauhc works . . . . . . £46,001 \irbmes and dynamos (3600 hp capacity at turbine shafts) . . 16,001 itep-up transformers and switchgear (3450 h p capacity) . . . . 6,001 "ransmission line (1 circuit of 3 wires, each 3/10" dia.) .. .. .. 10,501 tcp down transformers and switchgear (3000 h.p. capacity) .. .. 5, 501 84,001 Suildmgs, engineering costs, and sundues . . . . . . 7,00< Total