HYDRO-ELECTRIC SCHEMES

Nelson Evening Mail, Volume LIV, 14 July 1921, Page 7

HYDRO-ELECTRIC SCHEMES

COST OK STANIJ-UV I'I.A.VI

Tlie stand-by plant would bn localed in Nelson. It is proposed to install two units, each 250 h.p. Tin* first unit would he installed as soon as possible. Tlie power house, however, would be designed to lake tlie two units without altera i ion.

The cost ol bids class oi machinery is hard to determine under the present' conditions of the market. VVe have he lore us one example where the cost ol such a plant of about 2000 h.p. recently imported was oyer £(!<) per h.p., complete, with buddings, etc. It is true that in tin* ease mentioned the contract was let without any tendering. On a compctilive basis, which is ve;y desirable to-day, we think that for the size you require an up-to-date steam plant should he installed tor C 25 per'h.p. plus Inundations and buildings. The cost of building and foundations tor two units, each 2do h.p.. would lie 03,(XX) Tlie cost old set of 2.10 h.p. 0,-00 09,200 Plus 10 per cent. 025 £10,175 Plus value of site and ax>cess 5(X.) £10,075 lat year’s intern'd ;u 7': p.c. 1,800 £11,475 The total cost, of the BfcancDby plant with one unit. 250 h.p. mtsaUed and provision made lor a further unit ol 250 h.p., including nil cLarges aiid first year’s interest would, he Lupwiu. The, cost of. the buildings given above may be reduced, but it is not desirable to lower the estimate at this point. Wo believe that the cost ol the plant will he lower in the near future, and that it would not be wise to enter into a proposition of this sort on the top of the market.

ORDER OF PROCEDURE If it is decided to proceed with the Wairoa scheme the rock at the clam Site will have to he stripped and the bottom tested. The first unit of the stand-by plant could be erected, in about a year’s time while the dam is in. progress. Tliis would create a demand so that on the completion of the hydro plant, a ready market would be found for current; as an alternative, in “view of the present financial stringency, it may be wise to limit the Council’s present commitments to the first unit of the stand-by plant alone, and run it as a supply station until the time is oppoitune to proceed with the hyciio scheme.

OPERATING COSTS

Tf the total capital expenditure on the hydro-electric scheme and the stand-by is £138,000 and the capital is raised at 0 per cent interest and lj sinking fund the annual capital charges will amount The working costs for the hydro plant alone per year will be 1» 6G0 £12,000

If it were possible to obtain the necessary current from the Government supply, and the existing schedule rates were maintained, the cost of the current to the City would be £9,000 per year. , It will therefore be seen that while the Wairoa River may he the best source of supply in your district, it is probable that the charges for current to your consumers will bo 33 per cent higher than, say, from Mangahao, Hora Hora, or Lake Coleridge. reticulation We have nob included in this report the cost of reticulating the City. Ims is a matter which can bo gone into when the main question of adopting Wairoa or any other scheme has been settled.

COMPARISON WITH STEAM PLANT

In order to compare the Wairoa scheme with a modern steam plant we. have to assume the running conditions which would ho obtained by a- 1.-,’dro plant, although noth a steam plant it mav not be economical to attempt to achieve those conditions. The conditions assumed will ho 33 per cent load factor and continuous running. With a steam plant it may he. decided not to have continuous running, and so save wages, hut with the hydro plant under automatic control there would be nothing saved by depriving your customers of a continuous seivice With a steam plant von would not ho in a position to make attractive power rates for consumption oil peak load hours, and your load factor will not reach 33 per cent for some years. While this will reduce your coal consumption it will also reduce your revenue and will not stimulate your city and district in the industrial field \ hvdro plant has a special added value ‘by being able to give cheap power off peak load hours and so promote special industries. ; With a steam plant every unit developed takes a corresponding amount of coal, and wages which have to lie paid, and therefor a much cheaper rate off peak load hours is not possiblc A steam plant of 1250 h.p. of the most economical design, will cost m running order, including first year s interest and sinking fund, building accessories, purchase of ,-JV 1 expenses, not less than £36, 000. This cost can only he achieved by keen competitive tendering and represents not only the purchase of the machinery but the total capital expenditure of the whole outfit in running order. Wo do not put it forward as a sale estimate upon which to raise money, but as an estimate for comparison purposes only. . With the average running conditions that would obtain, in a_ small plant with the fluctuation in demand and banking of fires, the coal consumption, including all auxiliaries, will not lie less than 31bs of Westport coal per brake h.p. per hour. We know that on test a bettor poiformance is obtained, but we are row considering actual year_ in and yoai out running. On a basis of 33 per cent load factor the annual consumption will be 5000 tons of coal. With continuous running and working on the smallest staff, the wages, oil| etc., repairs, and general maintenance will amount to not less than £2400 per year. We have now to consider the capital charges and fuel account, and as we are uncertain of coal costs to your port we put it as 1 ellows :

Capital charges on £36,000, ( at 7)- per cent _ *■3, Working cost, nob in cm amp; fuel 2 >' £5,100 (To he continued).