STILL CLIMBING

Evening Post, Volume CXXV, Issue 151, 29 June 1938, Page 14

STILL CLIMBING

DEMAND FOR POWER

SOUTH ISLAND MARGIN

THE COLERIDGE PROBLEM

When in 1911 the Lake Coleridge hydro-electric scheme was commenced and then in succession the Mangahao (1922), and Waikaremoana and Arapuui systems (1925) ■were put under way the gloomiest forecasts of the results of building years before the need were made. These forecasts have not come true, for as each development has been inade another has already been under way or overdue. Once again, demand Js overhauling capacity, either to generate the power or to get the power to the point of demand.

The first section of the Coleridge scheme was completed in 1915, to 5300 kilowatts, and was extended to 26,495 ] k.w. in 1926, and again to 40,640 k.w. 1 in 1930. Mangahao's output was mopped up almost before the scheme was completed. Waikaremoana came ■ in in time to meet the still-growing . demand. Arapuni was extended and extended again to the fully-planned , capacity several years before pro- ; gramme development. MAJOR EXTENSIONS. In the South Island operations at the Waitaki station were commenced in 1934, and today the Government has before it tenders for plant to double the output from this station. A third huge turbo-generator is on the road to Waikaremoana now, and a Public Works camp below the present station is busy with the work preliminary to the building of a second station, to use over again the water that has passed through the turbines of the upper power house, A CASE NEARER HOME. Wellington City has a first rate standby steam station, supposedly, in general opinion, well able to look after Wellington's demands should the main supply for any reason fail, but that is not so, for Evans Bay cannot today meet the peak of a winter's day demand, by several thousand kilowatt. Everywhere the demand for electrical power has climbed, and it has not nearly reached the top, either for industrial uses, in which New Zealand has still a very long way to go; for haulage, for railway electrification is just beginning in the North Island; in city uses, for each day a new use is found; and in rural areas, some of which are not yet nearly fully reticulated, though New Zealand as a whole stands high as regards rural power service. COLERIDGE AND WAITAKI. How small the margin is between output and demand has been brought home by the as yet not traced complication at Lake Coleridge, for the South Island has learned that it has, for the next few weeks, a nice safe margin just as long as things run smoothly, but should the leak trouble develop into anything immediately serious then there will be no margin. The Coleridge scheme was developed in two sections, fed by two sets of pipe lines. ' The old station has ' a maximum capacity of 16,000 kilowatts; the leak trouble does not concern this section. The new station has a capacity, all out, of 30,000 kilowatts, and may or may not be seriously affected by the tunnel leak. Waitaki, which is bound up with Coleridge in the same way that Arapuni, Waikaremoana, and Mangahao jointly supply the North Island, has from its two present units a maximum capacity of 33,000 kilowatts. DOUBLED IN FOUR TEARS. In 1931 the peak demand upon generating plant in the South Island was almost 30,000 kilowatts. Then the bad years came and 30,000 was not quite reached in 1934, but each year since then seven or eight thousand have been added. Last winter the top demand was over 52,000, and this year 60,000 kilowatts may be reached and passed, during the next few weeks, after which the peak winter load may, on the experience of past years, be expected to fall off fairly rapidly towards the year's average demand. So it is that Waitaki's two great units (say, 33,000 k.w.) and the old Coleridge station (say 16,000 k.w. all out) would be hard put to it to meet a total demand during the mid-winter ■weeks of probably 60,000 k.w. The engineers are not alarmed. No leak is welcomed in a hydro-electric system, but after its first rapid increase in volume the tunnel leak has recently remained unaltered, under a steady watch and, measurement.

With the peak winter week demands past the difficulty of whatever repair work may be necessary will be much reduced.

When the plant at Waitaki has been doubled then the South Island will be so much further ahead again, but for how long? In the North Island the total demand is nearly threefold that of the South Island—l7B,ooo kilowatts has been reached —but there is still a margin in generating capacity in the combined Arapuni-Waikaremoana-Mangahao system. The problem is to provide for the transmission of power to the points where it will be demanded as the load climbs steadily higher. Just so much water can be forced through a water pipe, and just so much power can be carried by a long-distance transmission line. Far from hydro-electric development having run away from demand, demand is treading on its heels, though once again extensions at Waitaki, the second power station at Waikaremoana, and big transmission line works in the North Island will give it a temporary lead again in the next few years.