Geothermal Steam or Cook Strait Cable?

Press, Volume XCVI, Issue 28321, 5 July 1957, Page 10

Geothermal Steam or Cook Strait Cable?

The letter from the Commissioner of Works (Mr F. M. H. Hanson) to his Minister (Mr Goosman) should dispose of the fear that there is a fundamental conflict of opinion between the Ministry of Works and the State Hydro-electric Department on power generation. The suggestion had been made by Labour Party speakers in the Supply debate that the Ministry of Works was unhappy about the Cook Strait power cable and that it favoured greater development of geothermal generation in the North Island. Their contention was that the Government should defer a decision on the cable project until more was known about the potentialities of the thermal area, which they appeared to consider immense. This contention hardly required Mr Hanson’s letter as contradiction. The report of the special joint committee on power showed that even the maximum planned development at Wairakei (the total capacity of which is little more than half the capacity of Benmore) and the construction of all proved North Island hydro-electric schemes would leave the North Island short of power from 1963 onwards. The geothermal programme is open to some doubt. Earlier this year the English consultants, Merz and McLellan, advised that the third stage at Wairakei (increasing the output from 151,000 kilowatts to 250,000 kilowatts) should not be proceeded with until more reliable evidence of steam supplies was available. “ It cannot be ex“pected that the present high “ rate of steam-winning can be “ maintained indefinitely, as * diminishing returns must “ sooner or later be expected they said. The power programme can scarcely be held up while Labour’s confidence in tV airakei and neighbouring fields is tested. The essential fact is that a decision must be made now to the North Island’s

shortages from 1963 onwards. The most promising method of overcoming them economically is by the transfer of power from the South Island, though that cannot be effective until 1965. If the Government delayed a start on the Benmore project while it gambled on geothermal generation, it might plunge the Noiijth Island into a disastrous power famine 10 years hence. On the other hand, the Benmore station will produce the required power with much greater certainty and probably with greater economy. The one point where Mr Hanson, surprisingly, appears to differ from the State Hydro-electric Department, is in the urgency of making a decision about the Cook Strait cable. There is, as he says, “no “ desperate hurry ” to start on the cable; but there is a desperate hurry to start on the station to generate the power. The Benmore station would not be started yet for the -South Island alone, because it would be an unnecessary extravagance, giving a capacity of 480,000 kilowatts to meet an increase in demand over the next 13 years, only 180,000 kilowatts above the present capacity. Such extravagance would naturally be reflected in consumers’ accounts. If Benmore is to meet the urgent needs of the North Island it must be started >as soon as possible. One aspect of linking the two power systems has not perhaps received the attention it deserves. Water conditions in the two islands are dissimilar, the North Island rivers having their peak flows in the winter and the South Island rivers having theirs in the summer. Again, peak loads occur at different times. Connexion of the systems, in effect, would give extra generating capacity without providing any more generators. Other advantages would be in opportunity for maintenance work on generators and in organising the construction of new power stations.