Future Of Waitaki Basin Power

Press, Volume CIII, Issue 30431, 4 May 1964, Page 1

Future Of Waitaki Basin Power

Will the second half of the power potential in the Waitaki river basin, some 800,000 k.w.— nearly as much as the combined output from Benmore, Waitaki, and Aviemore—be used?

This is the tantalising question occupying the minds of the Ministry of Works and New Zealand Electricity Department engineers who are juggling with the water levels of the Waitaki to bring the Benmore project into operation and get the Aviemore project under way to give New Zealand 760,000 k.w. more power by 1970.

Since World War 11, the national demand for electricity has doubled every 10 years. Therefore the 800,000 kw that can be obtained by three more planned projects in the Waitaki basin will be needed.

However, the Ministry of Works project engineer at Benmore (Mr G. A. Tait) and the New Zealand Electricity Department resident engineer (Mr D. W. Douglas) at the week-end both made it clear that the development of the remaining potential will be almost purely a matter of economics.

If power from the planned Ohau (500,000 kw Pukaki (135,000 kw and Maryburn (50,000 kw schemes can be fed into the national grid at a cost a unit cheaper than other schemes currently being investigated in New Zealand, then they will certainly go ahead. A big factor in the determination of costs is the Otematata village, which can accommodate 1250 workers and their families. The village, sprawled over 340 acres, has a capital value of £l.sm. Costly Business Workers from the village have travelled three miles and a half for six years to the job at Benmore. Gradually, they are changing over to travel 11 miles to the Aviemore project. The building of another village and the transport and assembly of the skilled protect workers on another nower station job (at the Wanganui project, for example) is patently a costly business. Another, not so obvious, cost factor which will help to make future development on the Waitaki comparatively economic, is the years of research and investigation put in by the Ministry of Works and the New Zealand Electricity Department. Since the establishment of control dams at Lake Pukaki and Tekapo. and as far back as 1904, power engineers have been investigating the Waitaki river.

The Waitaki basin, from the catchment areas on the Main Divide, through the Tekapo, Pukaki, and Ohau lakes, down the river to its mouth, must be the best known area from hydraulic, climatic, and geological noints of view in New Zealand.

Against these factors of cost, may be balanced the relatively enormously different demands for power in the North and the South Islands. Mr Douglas said that the demand for power in each island was the same a head

of population. This makes the demand in the North Island twice as big. - Mr Douglas was also at pains to emphasis that the New Zealand Electricity Department and power-planning committees now regarded the electricity distribution system in this country as a whole—a national grid, as opposed to North and South grids. The basis for this conception is the Cook Strait power cable, through which electricity will be fed from south to north.

Through the Benmore valvehouse, a maximum of 600,000 kw of power will be able to be fed through the national grid to the North Island.

But this is a “package deal” (estimated to cost from £lom to £lsm). If more than 600.000 kw of power is wanted to be fed from the south to the north, more cables will be required to be laid across the Cook Strait, and extra valvehouses (for conversion of power from alternating current to direct current and reconversion).

In other words, if the demand in the North Island continues to grow at a greater rate than in the south, and the North Island hydro-electric power resources continue to be more costly to develop and relatively scarcer than the South’s, the economics of feeding more power from south to north must take into account the cost of further conversion and cable equipment (another £lom to £lsm for another 600,000 kw from south to north). Advocated in 1950 The scheme to feed power from south to north was first advocated officially by Mr M. G. Latter, then chief engineer of the New Zealand Electricity Department, in 1950. The question became a political football, and instructions to go ahead were not given until 1961. Both Mr Douglas and Mr Tait, understandably, refused to commit themselves on the future of Waitaki basin as a source of power beyond the Aviemore project—beyond five years. However, Mr Tait said that investigations into the potential power schemes at Lakes Ohau and Pukaki and at Maryburn were continuing.

There is no joy and no peace which can compare with the joy and peace of him who is understood and forgiven.— Dr. Charles Malik.