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APPENDIX D. ANNUAL REPORT ON ELECTRICAL WORK AND POWEE-SUPPLY UNDERTAKINGS, BY jTHE CHIEF ELECTRICAL ENGINEER.

The Chief Electrical I&jiginher to the Minister op Public Works. Sir, — Public Works Department, Wellington, 20tli August, 1917. 1 have the honour to submit the following report respecting the development of waterpower by the State, the issue of licenses for the utilization of water-power by other parties, and for the distribution of electricity. Lake Coleiudge Works. The Lake Coleridge hydro-electric power supply completed its second year of operation on the 31st March last, and has s now yielded definite industrial and financial results. The total capital outlay was increased during the year from £.320,330 to £366,984, the main item of expenditure under the heading being the installation of a fourth generating unit of 1,500 kilowatts capacity, raising the total power-house capacity from 4,500 kilowatts to 6,000 kilowatts, equivalent to 8,000 horse-power. A fifth turbine and generator set of 3,000 kilowatts capacity, together with material for an additional pipe-line, have been on order from some time. The manufacture of the turbine and generator is well advanced, but the prospects of getting delivery of the pipe-line are somewhat remote. As every effort to obtain a permit for the manufacture from the Home authorities has failed, efforts were made in Australia, in Canada, and in the United States to obtain a supply of steel plates for this purpose, but without success. Whenever we succeeded in obtaining quotations the prices were found to be prohibitive and delivery uncertain. The possibility of using wood-stave pipe for the upper portion of the pipe-line has been considered, and experiments are now being conducted with a view to testing the suitability of this class of pipe for the requirements. It is true that wood-stave pipe requires as much steel in the form of bands as an all-steel pipe, but the steel is in a form which is more readily procurable under present conditions. The delay in obtaining delivery of the fifth unit and pipe-line will cause a shortage of plant to meet the demand which will be felt very acutely in 1919, and to a lesser extent in 1918. The rainfall over the year has been below the average, whilst the rainfall during the season has been abnormally low. This, following upon a, succession of dry seasons, has resulted in the ground waters being drained, which will require time to replenish. The supply, however, lias been adequate for the requirements up to the present, but in view of the growth in the demand for power it is deemed advisable to make preparations for augmenting the supply of water, and a scheme has been prepared for diverting a portion of the Harper River when and as required, at a total cost of £-12,600, of which £5,150 is for a water-race and intake works, together with land-purchase, roading, and accommodation for workmen, the remainder being for river-diversion works designed to confine and maintain the river in a channel suitable for the purpose in view. The proposed diversion works would provide for about two and a half times the present output from the power-station, and is deemed to be ample for a long time to come. During the last dry season the storage in the lake was drawn upon to a depth of 22 ft., at which level it remains at the present time, and in order to restore the level the rainfall between this and December must be above the average. In view of a possible deficiency in the rainfall, and in view also of the growth in the power-output, it is desirable that the work of constructing the intake works and water-race should proceed as soon as possible and be completed during the coming summer. The completion of the diversion-works is not an urgent matter, but a commencement should be made with willow-planting, &0., next season, with a view to confining the river to its present channel, which is favourable for our purpose. No extension has been carried out to the main transmission-lines during the year, but the existing lines have been thoroughly overhauled. Insistent demands for supply of power have been received from Timaru and other localities on the main route between Lake Coleridge and Timaru, but owing to a scarcity of men and material due to the war the construction of the necessary transmission-lines has had to be postponed. Considerable extensions were made during the year to the primary distribution-lines from the Addington Substation, which now extend to Kaiapoi on the north, Lincoln and Tai Tapu on the south, Lyttelton on the east, and Templeton on the west, comprising a total route mileage of 57| miles. Applications for an extension of the primary distribution-lines have been received from Rangiora, Akaroa County, and Ellesmere County, but their requests have had to be declined for the present owing to stringency caused by the war. During the year retail reticulations have been erected in Lyttelton, Kaiapoi, Cashmere, Uiccarton, Hornby, and Templeton, and in most cases arrangements have been completed for the sale of these local reticulations to the local authorities, the Department reserving only the wholesale consumers and the bulk supply to the retail authorities. The results of the operation for the year have been very gratifying. The demand grew rapidly, and at the end of the year the connected load reached a total of 17,083 kilowatts, made up of 7,013 kilowatts in wholesale consumers and 10,070 kilowatts distributed over , thirteen local retail reticulations, of which the largest is that of the Christchureh City Council (8,817 kilowatts). The total energy issued from the power-house during the year amounted to 14,774,960 kilo-watt-hours, to obtain which 20,000 tons of coal would be required if generated in the most economical way by means of a steam-power plant of the size of the Lake Coleridge plant. The saving in coal is, however, much greater than this, as small-power plants are much less economical, and thei saving may certainly be put at 30,000 tons per annum, and probably 35,000 tons. In addition to this saving the power-user obtains his power for one-third to one-half the previous cost, so that the saving to the community is considerable.