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1904. NEW ZEALAND.

NEW ZEALAND WATER-POWERS, ETC. REPORT ON) BY Mr. P. S. HAY, M.A., M. Inst. C.E., SUPERINTENDING ENGINEER OF THE PUBLIC WORKS DEPARTMENT.

Presented to both Houses of the General Assembly by Command of His Excellency.

Public Works Department, Wellington, 16th September, 1904. Memorandum for the Hon. the Minister for Public Works. I have the honor to submit the following report embodying all the information collected to date regarding the water-power available in the colony. Some of the larger schemes outlined may at present appear to be of speculative interest only, as industries of magnitude sufficient to utilise the power available in these schemes may not seem likely to be develope deven in the near future ; but I think it is worth while to make the list of schemes, as at present known, from the largest possible to the smaller ones, as complete as the information now available allows, so that further investigation and discussion may result, and the probable magnitude, cost, and economic value of each scheme or any of its alternatives be more accurately determined, and an outline at least be got of the total amount of water-power available in the colony. In formulating schemes and estimating their costs there appears at once the question of the probable number of shifts per day of twenty-four hours which will be worked in the industries of the future that may use electric power. In general the cost for hydraulic works, hydraulic and electric plant, <fee, will be much greater for any scheme working eight hours or sixteen hours per day than for one working twenty-four hours per day; in each case all the water available for the scheme being supposed to be used. The conduits require to be larger to deliver the same quantity of water in the shorter time each day; the water-motors, the electric generating plant, also the transmission-lines, must be of increased capacity. The gross revenue will be approximately the same in each case (all the energy being sold) ; but in the shorter-time schemes the interest, and perhaps the renewal charges, will be greater. This question only affects lake schemes or others where adequate storage is possible. Where rivers or streams are utilised, and no storage is possible, then the plant has to be worked continuously, or water must run to waste. Full power for twelve hours per day, or, better, eighty-four hours per week, may, for a preliminary investigation such as this, be taken as equivalent to working at variable power extending over two or three shifts per day each of eight hours. Throughout this report 80 per cent, efficiency is taken for all water-motors, and the power given is brake horse-power (b.h.p.) on the turbine-shafts. Probable losses of head in races or conduits and pipes have been deducted before computing the horse-power. In schemes where storage is obtainable, a large part, and in many cases all of the Sunday and holiday surplus flow would be available for increasing the average power during working-days. No notice of this has been taken in estimating the power in any scheme. When complete information is available for any proposed scheme, designs for actual working would probably be based on a flow greater than the mean annual flow taken herein. For this reason many of the lake schemes might for actual work-ing-days be greater than stated by a considerable percentage.

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