COOK STRAIT POWER LINK

Press, Volume XCIII, Issue 27911, 7 March 1956, Page 10

COOK STRAIT POWER LINK

Plan Includes Station At Benmore

OUTPUT GREATER THAN ROXBURGH

(New Zealand Press Association)

WELLINGTON, March 6.

The Government will build a hydro-electric generating station, bigger than Roxburgh, at Benmore, on the Waitaki river, if a submarine power transmission cable across Cook Strait proves practicable. Investigation of the site for another large station is also planned.

The Minister in charge of the State Hydro-electric Department (Mr W. S. Goosman) made this announcement this morning. He said that the sta'tion at Benmore, which would have an installed capacity of up to 350,000 kilowatts, was a major part of the first stage of development of the Cook Strait cable project, now being investigated by the Government. The proposed station at Benmore, including the cost of laying cables across the strait and building transmission lines from the station, was estimated to cost £38,000,000, said the Minister.

Roxburgh, which will be the biggest hydro station in New Zealand when it is finished, has a capacity of 325,000 kilowatts, 25,000 kilowatts less than the proposed new Waitaki station. The Minister said that if the result of the investigation into the practicability of a sumbarine cable across Cook Strait was favourable, “we would launch an extensive hydro construction programme in the South Island, where we would build both for the power supply needs of the South and of the North.”

The investigation of the Benmore site had been completed, and the new building programme would begin there. During the building of this station, investigations would be pushed ahead for the construction of another large generating station. “If, after investigation, the cable project were approved,” said the Minister, “it would take about six years to construct the power station, which would be another Roxburgh, but the manufacture and laying of the submarine cables could be done in about three years. If the project is to be in service by 1962 or 1963—the date by which it is estimated the north-south service will be needed—there is no time for delay.” Mr Goosman said that preliminary investigations had shown that the cable project had economic advantages so great that the Government had decided to make full -nd detailed investigations immediately. Details of First Stage The first stage of development of the project would include the following main features, he said:— A hydro power station of up to 350,000 kilowatts capacity, possibly on the Waitaki river. (Benmore or its equivalent would be suitable.)

A high-voltage transmission line about 350 miles long from the power station to Cook Strait. A sub-station in the Picton area. A number of submarine power cables across Cook Strait on a route to be determined after survey. A short high-voltage transmission line from the North Island terminal of the submarine power cables to connect with the North Island power system near Wellington.

The capital costs of this development, Mr Goosman said, were estimated at £38.000.000. “This,” he added, “corresponds to a total capital cost of about £llO a kilowatt of generating capacity, which compares favourably with an estimated average capital cost of £lO9 a kilowatt (without including any transmission costs) for the four later Waikato stations—Whakamaru, Atiamuri, Waipapa, and Ohakuri. “The estimated cost of delivering power in bulk into the North Island power system at Wellington would be less than Ad a kilowatt-hour, and actually slightly less than the cost of supplying power from the Waikato hydro stations I have mentioned,” said the Minister. “Power from the South Island would not be required in the North Island until the North Island load exceeds the capacity of the existing North Island power stations plus the capacity of those power stations under construction. approved for construction, or definitely planned for construction. “It is estimated that the date by which the north-south connexion would be required to be in service would be 1962 or 1963. “The economic savings that appear to be inherent in this project, will,

I am sure, appeal strongly to all prudent New Zealanders,” said Mr Goosman. “It is an attractive prospect that the Government must examine. if it is to fulfil its role of providing the people with the services they need and use. “Reports already made on it by the Government’s officers give it clear advantages over fuel and nuclear-fired stations from the consumer’s point of view. Savings of the order of £10,000,000 and more a year are in view after 1972. It would be worse than foolish not to go after them.”

The Minister added that the survey in Cook Strait was being carried out by the Royal New Zealand Navy and the Department of Scientific and Industrial Research to the requirements of the investigating company appointed by the Government. A survey motor launch and an auxiliary vessel were being used in the first stage of the investigation, during which seismic soundings would be made to determine the depth of sediment lying on the bottom of Cook Strait. Later, possible cable landing points on both sides of the strait would be surveyed, and when this information had been gathered the most suitable route for the cable would be selected, should the project be approved. Route of Cable The Wellington reporter of “The Press” says that the projected cable would probably run from near Cape Terawhiti to near Wellington Head, on the southern side of Cook Strait. Instead of being a north-south cable it would run almost due east and west. This is the shortest possible distance across the strait, and is the route now being surveyed. A spokesman for a- State Hydroelectric Department said today that it was hoped that a suitable route would be found somewhere along this line. This would ensure that the total length of undersea cable would not exceed 20 miles. The principal reason for requiring the shortest possible length of cable is not, as is popularly supposed, to cut transmission losses, but to reduce the very high capital cost of a cable. This is expected to be about £3.000,000. It is not expected that a cable would have to be laid in waters more than 900 ft deep, but detailed measurements of the strength of currents on the sea bed will have to be made. As there are likely to be numbers of small ravines across which a cable would be suspended, strong currents could cause abrasion of a cable at points of suspension.