HYDRO-ELECTRIC POWER

Dominion, Volume 10, Issue 3010, 22 February 1917, Page 6

HYDRO-ELECTRIC POWER

BIG SCHEME FOR NORTH ISLAND THREE CENTRES FOR POWER SUPPLY TO COST A MILLION A document of great public interest was the interim report by Mr. Evan Parry, the Government's expert in hydro-electrics, which was presented by the Minister of Public Works (Hon W Eraser) to the Mayor (Mr. J. P. Luke) and a deputation of representatives of local bodies in the course of an interview' yesterday morning. Mr. Parry has been investigating schemes for sup. plying the whole of the North Island with electrical power. Modern Idea—Great Common Power Centre.

The fundamental principle involved.,- he says, "is that, of centralising the power-generating plant and concentrating it into a few large units where the energy can he generated under more economical conditions than in small units, and transmitting the power so generated to the individual powerusers. By this means both labour and iuel are economised even where the centralised power plant ttepends on fuel for its motive power, and much' more so where water is available as a motive power. It is quite possible ana mI? t supply the whole o f the Aorth Island from one single source, more or less centrally situated, but there is no single source of power in the North Island which can .be regarded as sufficient for all time-even if one- source were to be selected for the time being, sooner or later it would require to be supplemented by the development of other sources. Again, the distances of transmission resulting tram tho development of a single source, whilst not excessive, are yet somewhat great for the amount of power at present to be transmitted. This objection is not a vital one. lie determining factor in tho question is the nature of the country through which a great deal of the transmission lines would require to be brought. A single source of supply would involve the erection of some hundreds of miles of transmission lines over broken country of suoh a nature as to offer a serious obstacle in tho way of repair and maintenance, and having in view the importance of maintaining a continuous and uninterrupted supply, it i 3 an essential condition that the transmission lines should be as accessible as possible." Mr. Parry insists 'that small water power supply systems of less than about 10,0UU horse-power cannot be economically developed for a general supply to a large district which carries with it the necessity of adequate storage to maintain the supply at all times. The capital cost of head works, power station, and plant, including everything up to the point of transmission, should not exceed £20 per horse-power, 'otherwise, when account is taken of the cost of transmission, the extent of the capital expenditure will tend to swamp the advantages to be derived from substituting waterpower tor fuel. A Triple-Headed Scheme. The scheme which best satisfies all requirements is one in which at the outset three waterpower sources would be deve oped for supplying respectively the Auckland district, the Hawke's Bav district, and the Wellington district ihese sources would in the ordinary course of development bo linked up together, and by reinforcing each other provide additional guarantee of continuity of supply. The best source of power for Hawke's Bay district is undoubtedly Waikaremoana. The amount or power obtainable from this source is greatly in excess of the requirements ot this district, and it should be regarded as a supplementary source for supplying the Wellington district. Very complete surveys have been carried out during.last year, and accurate measurements made of the flow, and all tie necessary information obtained to enable the most economical method of development to be prepared and carried out. f,

'Tor the Auckland district, consider, ation was given to the plan of taking over the Hora Hora works of the Waihi Company, winch the Government has power to do under the license, but " says Mr Parry, "the best source so far !'? fou " -m- 10 he th . e Arapuni Gorge, on the Waikato River, where 120,000 horse-power can be obtained on tho basis of a 50 per cent, load factor, based upon the minimum observed flow of the W-aikato Eiver during a phenomenally dry season, which occurred in 1915 The gorge is about eight miles from Hora Hora, and complete surveys have been made during last year to enable a scheme of development to be planned.' J-ins scheme involves the construction of a dam on the Waikato Eiver, and before coming to a final conclusion it will be necessary to take prospeots to prove the suitability of tlie foundations. One objection to this scheme is that whilst the scheme is. an exceptionally economical one for the full development, the initial cost of the large hydraulic works required makes it unduly expensive, for partial development of wider 40,000 horse-power, but ir it can be found that within reasonable time there is a prospective market tor this amount, the development of this scheme would be justified on an economical basis. Some further investigation is necessary .before a final decision can be come to regarding the best source of supply for the district. As tor the initial installation of power and works, I would propose for the Auckland district a power plant of 30,000 horse-power, with trunk lines to Auckland on the north and! To Kiiiti and Hotonia on the south, with depots at intervals, and a system of primary distribution to serve tho intermediate towns and surrounding districts In order to provide for this plant and equipment a sum of £1.200.000 will be required. The Wellington Scheme. "As regards a source of supply lor the Wellington district, considerable difficulty has been encountered in finding :1 source much satisfies all the requirements because, although tiie rivers are numerous, they do not lend themselves to economical development, and as a rule the power to be derived from any I one source is small compared with the i requirements. It has been, suggested ! that the Hutt .River would iorm a suit- j able source for supplying the southern \ end of the Wellington district. The ] amount of water is barely adequate for the needs of Wellington' City, if pro- i vision is to be made for natural growth and progress, whilst for the amount of power available the cost of development is excessive. In any case, the amount of powor obtainable is not large enough to supply an extended district, whilst a power station in the Manawatti district isAvell situated for supplying Wellington, Wairarapa, and parts of the Hawke's Bay and Taraiiaki districts, having regard to the distances and the power to be supplied in each hr-ality. The most suitable source for Uie supply of the southern district is found to be tho Mangahao River. This river rises on the slopes of Mount Dundas on the

I Tararua. llanges, and flows into tlio Mauawatu near Woodville, and it is , found that by diverting through the hills for a total distance of three miles there is made available a fall of 1040 feet in the sixty-five miles of tivor between tlio Mangahao and the •• loop of the Manawatu, near Shannon. Tc is proposed to develop this source by tunnelling through the range from the Mangahao into the Tokomaru Vulley, there diverting a part of the Tokomaru, and then from the Tokomaru Valley R through into the valley of the Mangaore, with a power station situated ■within three miles of the railway at Shannon. Observations of fee flow v.-c-re made during last season, which was exceptionally dry, and arc also being made during the present season, and based upon the dry season How ib is possible to obtain 25,000 horse-power s jj on aSO per cent, load factor r.::sis, by n impounding the waters nnd inking nd•n vantage of the natural features of the country for the purpose. This is suftir cient to satisfy the power leq'ihements a of the district which it is intended to p serve for some time to come. Imt will ' require to be supplemented in due '" course as the country develops. The • natural extensions of the transmission *". lines from three sources will ultimately link them together, so that bv this means security will lie obtained, and also additional supply obtained for the Wellington district ~from the other sources. It is possible, however, that '- in course of time the requirements vill g be so great as to require another dei- volopmenfc in the Taranaki district, 0 where there is more than one promising t source. n A New Principle. , r ''In the design of this scheme I pro--2 pose to adopt a new principle in regard to the provision for a stand-by. It is ft necessary to provide an additional 1 • power unit over and above the power obtainable from this source so as to , permit of the overhaul and repair of machinery. The usual method is to instal an extra unit of water plant in £ the power-house. In the present inj stance I propose that the stand-by unit should he a complete steam set. £ The advantage of a steam standl-by set in this scheme is that not only does it j serve the purpose of a spare unit, but it also provides means of tiding over short periods of exceptional, or ab- \ normal, low water, thus enabling'the ' available water to bo -used to a larger \ extent. Tho additional cost of a steam |. unit over a water power unit is not , great, and tho cost of running on infrequent occasions would be a negligible ' proportion of the total operating cost, ! whilst the additional security and value l conferred! on the water power plant is out of all proportion to the sdded exJ pense. I would propose, further, that '. instead of installing the stenm unit at . tlio power-house, to take advantage of . tho fact that Wellington Oity has al- [ ready a. steam plant installed which is , of the capacity required for the pur- ; pose aforesaid, and as they will deem it advisable and! prudent to maintain . this in running condition to provide ; against temporary interruption of the i supply, which are inevitable on every : transmission system, thero should be no difficulty about coming to terms for , the use of this plant for relieving the load on the wsteiipower plant in case of necessity. Some modification of the existing Wellington plant may be necessary to fit in with this scheme, but this is a detail about which there should be no difficulty in a matter which is to the advantage of both parties. A Million of Money. "The cost of providing headworks, power station, and plant for 25,000 ihorse-power would be at normal prices £420,000, which is under the limit of £20 per horse-power specified above. This illustrates tho advantage of concentrating the power supply for a considerable distriot in one source. If, for instance, wo sought to provide for the needs of Wellington City and immediate neighbourhood only from this source, the cost of hydraulic works for the power required would l be excessive, whereas when developed for the full ,capacity and for the benefit of a larger area and population, it becomes a sound commercial proposition. As regards the area to be supplied, there is an economic limit to the area over which a given amount of power can be distributed, and one of tho obstacles to a satisfactory scheme of power supply in New Zealand at present is the small amount of power required per square miie of area supplied!. Having regard to this principle, and stretching it to tho limit, w« should be working on economical lines in serving the following districts from this source—the whole of the Wellington province as far north as Taihape and Wanganui, and the southern portion of Hawke's BayiC ; I would propose in the first place to run trunk lines to Wellington, Palmerston North, Wanganui, and Masterton as chief centres, and from these centres, as veil as from intermediate points on the trunk lines to provide the necessary distribution lines and sub-stations to servo the surrounding districts. "The cost of providing the trunk lines, distribution lines, sub-stations, and other services i_to give a supply in bulk to local distributing authorities i and to largo power users throughout this areaj would be £580,000, making a total of £1,000,000. which expenditure is at the rate of £40 per horsepower. The capital charges on this expenditure at_7J_per cent, to include interest, depreciation, and sinking fund, work out at £3 per horse-power per annum, the annual cost of maintenance and operation would amount to £!>o,ooo per annum, or the equivalent o f £1 per horse-power per annum. Both charges require a return of £4 on the average per horse-power per annum in order to i.provule for all charges with a reasonable provision for depreciation. We know by experience iir Cliristchurcli that we can secure this revenue without difficulty, evon where economical fuel plants are already installed. A Help to Wellington, "The development of the Mangatno would help' Wellington out of a difii- J ciilty, and the Government's point v of view Wellington alone would provide t an immediate load on the station of n about one-third its capacity, and would l< enable the large area outlined above i h to be supnlied at the same'time bofcVjk economically rmd advantageously. : ind i b tho prospective markets in these d?s- ! a tricts. oonili!>ip_d with the natural ic- i a crease in Wellington should ab'sorb the i « balance of the r.ower available in a very | tl short time. Complete surveys have I been made nf the- Mangahao sohem? I li and plans and estimates prepared. A| si survey of thi> transmission line between tl Shnnnni! and Wellington is procwrlijiir, S1 and will slmrtlv be poirmlet.ed. and this nos'tion of tin , siib-s'tMinii tn serve a Wellington and the. TTutt VaMev has a been located. ' °

"As regard?: the order of deve.l»ompnt. Wnikaremoana srhcmn should bo deferred for Win present. The development nf this source should to my mind, b» mode dependent unon the construclion of till. Napipr-Gishorno railway. The raihvav -would onpn up a better road for tlio transmission linos, jind rendor them n>nr<> nocpssible for tho construption and maintenance. ..At present this country is most difficult, especially from n maintenance point of view There is every reason also in favour of operating this railwav electrically. The Auckland and Wellington schemes should simultaneously. Tlio work ir. connection with tlio' latter, ■however, is more advanced, and if kborii' is obtainable, which i? very douhtful. the headwords could be' put in hand at once and prenared in readiness for machinery and nine linos. .Hiidi, however, could not bo' obtained during the continuance of the n-ar. A beginninc; could be made by constructing roadways for access to tlio head-

works.—(Sgd.) B. Parry, Chief Electrical Engineer." A Modified Estimate. In a memorandum to the Minister on the cost of the Wellington district scheme, Mr. Parry says: — "The total cost of supplying power to an area, comprising 'Wellington, PnTmerston, Wanganui, and Masterton, together with ,thc intermediate towns and surrounding districts, is £1,000,000, divided up as follows:— £ Headworks and generating plant £SO,OOO Transmission, distribution, and services £580,000 Total £1,000,000. "This scheme is not one which can he economically developed for less than its full capacity, owiug to the large expenditure on dams, tunnels, ' and other hydraulic works, the cost of which is much the same for any development, which is a typical feature of water-power developments, as the intake works, tunnels, end other works must of necessity hecome of a size sufficient to provide for the ultimate developments. If this scheme is required to be modified so as to provide for the immediate prospective needs of Wellington city and surrounding districts, the saving in heulworks would not he anywhere near in proportion to the reduction in capacity of plant. However, by leaving out. one storage dam, and a proportion of the pinework and machinery, a saving of £86,000 in tho initial outlay on the power works could hn ouw.ted. making the expenditure £334.000, instead of £450,000. The cost of transmission, sub-station, and distributors would amount io £114,000, making a total of £448,000. This, of course, involves a greater cost per horse-power provided than does the scheme when completed l to its full capacity for the benefit of the whole district. THE MINISTER'S REMARKS. A MATTER FOR PARLIAMENT. Replying to Mr. Luke, who explained the .position which had led up to the deputation, the Minister said that he could: not consider the Wellington soheme without considering schemes for the whole of the North Island. Under Mr. Parry's schemo lie recognised that Wellington would he the biggest consumer of power, ami therefore would produce the largest return in tho quickest time, but it had to he remembered that while the war was on machinery could not be imported. If Parliament agreed to the Echom« there wns nothing to prevent certain preliminary works berhg carried out, hut in any case- he> did! not think they would get hydro-electric power to Wellington 'until 2J or 3 years after the works had heen commenced.