CITY’S POWER SUPPLY

Press, Volume LXXIV, Issue 22467, 30 July 1938, Page 8

CITY’S POWER SUPPLY

WAITAKI NOT BEING USED TO CAPACITY

Chief Engineer’s Comment on Fears Of Shortage

The view that a power shortage in Christchurch was certain next year, and that the position in 1940 would be even worse, was expressed in a report presented to the Christchurch City Council last Monday. It was then stated that the Public Works Department had been asked for information on certain matters in the report, and the council decided to defer consideration of Mr Hitchcock’s report until a reply had been received from the Public Works Department. In this reply, Mr Kissel said that : the rate of increase during the last 1 year had certainly been phenomenal, j He thought, however, that this increase i could be divided into two parts, first 1 the re-establishment of normal growth j which was delayed, particularly in the ( South Island, during the depression: ( and, second, the normal growth on top 1 of the first. The second part also had ■ been in itself exceptionally high be- ( cause of the comparatively prosperous times at present existing. An ex- ' amination of the department’s graphs j of load over a period of years would \ appear to indicate that the present i high rate of increase would tend to < fall back after another year. J Flow at Waitaki 1 “You suggest that at the peak load period the small amount of water flowering over the dam would indicate that there is very little spare capacity,” Mr Kissel continued. “The mere fact that there has at all times been water flowing over the dam indicates that so far there has been water to spare at any. condition of ] loading, and that we have not been taking anything like-full advantage of the daily load factor or daily variation in load. Take the case of the present winter, with its peak of 60.520 kilowatts. To meet this we have a plant j with capacity of 65.000 kilowatts nor- j mal full load. Actually each station i can carry considerably more than its i full rated capacity, and the loads that < have been carried indicate that a load- i of more than 76,000 kilowatts can be 1 carried. So far this year we have i made practically no draw on storage ] at Lake Coleridge or at Lake Waitaki. i “With the storage available at Cole- 1 ridge, we can rely on having sufficient ] water to run its full plant t'o capacity < during the comparatively short period ‘ of maximum demand. During June— j which is almost invariably the period J of maximum loading—the water available at Waitaki in any one week was sufficient to generate 5.985,000 units, , which on the usual weekly load factor ] of 63 per cent, would provide for a , peak of more than 56,000 kilowatts at ( Waitaki. Actually, by drawing on the , Lake Coleridge seasonal storage and ' using the Waitaki daily storage, I am sure we could have carried at least 112,000 kilowatts in June if we had the additional plant at Waitaki. It is known that the June flow this year is not the minimum of the Waitaki. It may go, and has gone, lower, but low water is generally later than June and the load has then fallen off.” The department’s proposals to carry Waitaki-Coleridge supply to Southland would not very seriously affect the position of peak demands, as each of these places already had generating capacity. This generating capacity, particularly in Southland, could, after connexion with Waitaki, be used to much greater advantage than at present, because by using Waitaki in the summer the department could conserve water at Monowai, to be sure of having full capacity available in the winter. On the West Coast the generating capacity, with Diesels, was well in excess of the demand. In each case, therefore, the Coleridge-' Waitaki system would be required to cater for the actual increments, not the base load during winter peaks, said Mr Kissel. Questions and Answers Four questions were asked by Mr Hitchcock in his letter to the Public Works Department. They were as follows: — (1) Has there been’ a sufficient margin of water flow at Waitaki during the last winter load period, to provide supply for the two or even one additional unit? (2) If this winter’s experience has shown the available flow to be sufficient for these additional units, when does your department expect to have them in service? (3) If storage and control at the three lakes are necessary to augment the Waitaki winter flow for future generator capacity, when is it anticipated that these works could make their contribution to the supply? (4) If lake control cannot be available for several years, will your department consider the urgent installation of a fuel auxiliary plant of substantial capacity, to augment the Waitaki-Coleridge system? Mr Kissel’s replies were:— (1) During the last winter there has been sufficient water at Waitaki and Coleridge to have provided supply for two extra units at Waitaki operated to full load at the load factor which would be necessary on the present general type of load. (2) Two additional units for Waitaki have been ordered, and the contract provides for delivery of the first of these complete, ex works, by June 15, 1939. Transport and erection would take a further seven or eight months, so that it should be available for the winter of 1940. (3) It is not considered that storage and control at the three lakes are necessary to augment the flow to the four-unit development at Waitaki Control of one of them, probably Tekapo, would be first instituted. Detail surveys and exploratory shaftsinking have been done there to enable works to be designed. Construction work would. probably occupy from two and a half to three years. It is, however, more probable that the proposed power station on the Rakaia, at the end of the Rangitata irrigation canal, would be put in before the lake control works.

STATEMENT BY MINISTER

Department’s Reply to Council

“The mere fact that there has at all times been water flowing over the dam at Waitaki indicates that so far there has been water to spare at any condition of loading and that we have not been taking anything like full advantage of the daily load factor or daily variation in load.” This comment on the possibility of Christchurch experiencing a shortage of electric power in the next two years—as suggested by the general manager of the Municipal Electricity Department (Mr E. Hitchcock) —is contained in a letter received yesterday by Mr Hitchcock from the chief electrical engineer of the Public Works Department (Mr F. T. M. Kissel). Mr Kissel added that an examination of graphs of load over a period of years appeared to indicate that the present high rate of increase in consumption would tend to fall back after another year.

The headworks of the Rangitata scheme are, as you know, already well under way. and I have no doubt power could be made available in about three years if necessary. (4) It is not considered that a new steam plant of substantial capacity could be made available more quickly than could extensions to the hydro system. Its capital cost would probably be higher, and its operating cost would most certainly be very much higher than would the hydrosystem. Capacity of Plant In conclusion, Mr Kissel said it was somewhat difficult to set out in correspondence just how the two main plants at Coleridge and Waitaki would be utilised under different circumstances of water and load, but he was quite confident that with the present machines the department could carry the load likely to develop before the additional units at Waitaki arrived, and that with could carry peak loads up to the capacthese units installed the department ity of the machines for the short periods during which these peak loads existed. The department recognised that there was an obligation to supply all the load that was offering, and whilst desirous of having some spare plant available for the purpose, had also to remember that its costs were mainly capital charges, and for that reason it must be careful to see that development was not carried too far in advance of requirements.

MISUNDERSTANDING SAID TO HAVE BEEN CAUSED

The reply by the Minister for Public Works (the Hon. R. Semple) to an article by “Engineer” in “The Press” recently has, according to the chairman of the Christchurch City Council’s electricity committee (Cr. J. S. Barnett), given rise to a misapprehension. The article by “Engineer,” commenting on recent power shortages, was published on July 25; the following day there appeared a report by the general manager of the Muncipal Electricity Department (Mr E. Hitchcock) on the possibility of shortages affecting Christchurch; and two days later was published a statement by the Minister in reply to “Engineer.” It appeared, however, said Cr. Barnett yesterday, that the Minister’s reply had been taken by some people as relating to the report presented by Mr Hitchcock. Cr. Barnett said that the Minister’s reply was to the criticism expressed in the article by “Engineer." This dealt to a large extent with North Island matters, and was quite independent of the discussion at the City Council meeting on the evening of July 25 regarding the possibilities of a power shortage. The council had received a courteous and considered reply from the Chief Electrical Engineer of the Public Works Department (Mr F. T. M. Kissel) to the representations it submitted to the department. The Minister’s published comment replied very definitely to the anonymous criticism under the nom-de-plume “Engineer,” and not to the report of the general manager of the Municipal Electricity Department or to the discussion at the council meeting.