A POWERFUL LINK
THE COOK STRAIT CABLE
Two major technological ventures have had to contend with the treacherous seas that arise from New Zealand’s position in the roaring forties. One was the development of the Maui gas field; the other was the laying of the power cable between the North and South Islands.
The power cable also had to weather storms arising from differences of opinion between government departments, political parties and regions of the country.
Evan Parry in 1918
As we have seen, certain papers in early numbers of the New Zealand Journal of Science and Technology predicted or foreshadowed future developments. While the transfer of electricity from the South Island to the North was not specifically forecast, Evan Parry
enunciated the advantages that could come from the transmission of power over long distances when, in the very first number of the Journal, he discussed ‘The Economics of Electric Power Distribution’
. He wrote of
" the gain to the community as a result of concentrating the power plant, generating the electricity therefrom, and distributing it over a large area...".
In other words, the reduction in power cost that could be achieved through economies of scale more than compensated for the costs of long distance transmission.
In his comprehensive paper delivered at the Power Boards’ conference in September 1950 M.G. Latta, the Chief Engineer of the State Hydro-electric Department, identified the transfer of electricity from the South as being one of the more promising ways of meeting future North Island demand.
He recommended that it should be seriously investigated, thus signalling the start of a controversy that would last for over a decade.
To understand the vehemence with which views were expressed, and the considerable degree of political involvement in the issue, it is necessary to appreciate that since the mid-war years electricity shortages and hence power cuts had been chronic phenomena.
As in many Western countries at the time, demand was growing at a rate that required a doubling of generating capacity every 7 years (a growth rate of 10 percent per year). Not an easy thing to do, especially when the boom that helped create the demand was creating shortages of the capital and labour resources needed for power station construction.
One of the ways of providing big chunks of power is to build big power stations. The Waitaki River offered promising sites for these and Latta talked of sending 1,000,000 kilowatts (1000 MW) north. He had calculated that, using high voltages, the cost of transmission north, ignoring the need for a Cook Strait crossing, was not greater than 0.1d per kilowatt/hour (less than 0. l cent per unit). He did not know what an underwater link itself would cost but if the technical problems could be solved ’a very high cost could be economically justified and still enable hydro power to be supplied from the South Island to the North Island at a cost per unit comparable with or lower than by alternative means of production.’
An Unchallenged Logic
In the ensuing years, this argument would be lost sight of or ignored but nothing challenged its validity.
Latta saw the problem of getting power across the strait as not insurmountable and as likely to be reduced by prospective developments in high voltage direct current transmission. Although submarine cables were in use, none were of the length and capacity he was proposing, although various sizeable schemes had been put forward, including a link between Europe and Britain. In Sweden a direct-current (DC) link was being planned between the mainland and the island of Gotland in the Baltic, a distance of about 60 miles (100 kilometres).
The Electricity Department had already requested that the naval survey ship, ‘Lachlan’, make a preliminary survey of Cook Strait. Before any decision could be made on a route depth, tidal currents and the nature of the seabed would have to be established.
Over the next few years the Electricity Department built up its knowledge of the problem, watching with considerable interest progress elsewhere. It was unable to carry out extensive investigations, however, because it was not able to get the monetary authority it needed, the politicians having sensed from the first reactions to the issue that it was a tricky one.
A Planning Committee
The continuing problem of providing an adequate power supply in the North Island led the Government to establish a committee ’to study the position, consider ways and means of providing further quantities of electric power, and to make firm recommendations which in the opinion of the committee would represent the best way of meeting the present situation’.
From the planning point of view this was a turning point; for the first time projected load increases and a plan for providing new generating capacity to meet these increases were to be set against each other and made public.
The committee first reported in April 1955, having concerned itself initially only with the period up until 1962-3. After projecting an increase in demand of over 12% in the 1955-6 year it then postulated growth would taper off, falling from 8.4% in the 1956-7 year down to 6.8% in 1962-3.
This growth was to be met by the Waikato hydro stations then under construction, the Wairakei geothermal plant, and a new coal-fired station in the Huntly area, Meremere. The possibility of a gas turbine station at Wellington, which could be erected quickly and would shorten the period of power restriction by one to one and a half years, was to be examined.
Fully Commited Construction Forces
Although the cost of power from the coal station would be greater than that from new hydro, the latter would require twice the capital expenditure and could not be built so quickly and, in any event, the Ministry of Works construction forces were fully committed. The committee made the point that further large base-load hydro was not readily available in the North Island and that the time had come to install other types of power station.
In 1955 Latta used the pretext of attendance at the Geneva Conference on the Peaceful Uses of Atomic Energy to gain information on long distance transmission, submarine cables, and high voltage direct current equipment. He talked to authorities on these subjects in Sweden, Switzerland, the United Kingdom and Canada, and visited various installations, including the direct current system to Gotland, and submarine cable factories.
He returned from his trip with a ’definite opinion that a submarine cable was feasible and a strong recommendation that the Government should immediately carry out experiments’. In his report which was released by the Minister in charge of the State Hydro-electric Department, Mr. Goosman, in January 1956, Latta argued that because of New Zealand’s circumstances a strong economic case existed for marine power cables across the Strait.
Over the years millions of pounds could be saved by developing the very large hydroelectric sources in the south. None of the technical problems appeared insuperable; a careful choice would have to be made between alternating and direct current.
While the provision of cables for DC would be simpler and cheaper than for AC, conversion equipment, AC/DC and DC/AC, would be required at the ends and this was costly and operating experience with it limited. Latta recommended that a full and proper investigation should be carried out in New Zealand as soon as possible.
Benmore is Proposed
In March 1956 the seriousness of the proposal became apparent: the Government accepted an offer from B.I.C.C. Ltd (British Insulated Callenders Cables) to do a feasibility study on the cable for completion by the end of the year and, a few days later, announced that as part of the development it was proposed to build a great power station at Benmore on the Waitaki river.
If the cable scheme was approved, a six-year construction period for the power station would start, leading to possible completion in 1962-3. The total project was estimated to have a capital cost of £38,000,000, which on a per kilowatt basis compared very favourably with the later developments on the Waikato in the North Island.
During 1956 the committee set up to look at the provision of future electricity supply was re-formed to include engineers from South Island supply authorities as well as those from the State Hydro-electric Department, the Ministry of Works and the North Island authorities. This allowed the consideration of South Island supply after Roxburgh was completed and of the possible interconnection of the two power systems. By March 1957 the committee was in a position to report on a supply plan through until 1970.
In doing this it had available to it a report from Merz and McLellan on extensions to Wairakei geothermal plant, and various reports on the cable proposition together with Latta’s analysis based on these. Latta’s case was apparently sufficiently convincing for the committee to recommend that ’firmly believing it to be practicable and economic, approval in principle be given to the proposal that the North and South Island power systems should be interconnected by a direct-current link designed for capacity of 600,000 kilowatts and capable of further extension.’
The committee also recommended that the extensions to Wairakei should proceed. The link was required to be in operation at the same time as Benmore.
The whole case for Benmore rested on its association with the link, for without an ability to transmit power north the large capital expenditure on a power station whose capacity would put the South Island in surplus for about nine years could not be justified.
Superior Direct Current Costs
Latta gave cost data showing the superiority of direct over alternating current for power transmission from the Waitaki to Wellington. Direct current could cost £16 million against £26 million for an alternating current system.
The project was considered entirely practicable. The surveys had shown that in the bottom of the Strait, the area of interest was reasonably flat, and largely free from rocks. The maximum depth on the proposed route was 900 feet and it was expected that the cable could be laid on sediment, although it would be suitably armoured in case rocks were encountered.
The preferred area of cable laying was outside the bounds of the notorious Karori and Terawhiti tidal rips. Cook Strait’s changeable weather was acknowledged and this meant that the cable laying procedure should not take more than 24 hours for each of the three cables, (one of these would be spare).
Implicit in the choice of the much cheaper DC system was the belief that the equipment to be used for the conversion from AC and back to AC again was reliable and would perform to specification. The Gotland installation, which had been operating for two years, was the only one of the kind in existence and development work would be necessary to update the performance of the equipment used there to deal with two and one half times the voltage and six times the current.
The valve manufacturer A.S.E.A. was ’ absolutely certain’ that this could be done, and another scheme due to proceed, the English Channel project, was likely to have valves with a rating only slightly less than those of the New Zealand proposal.
Independent Technical Advice
Mindful of the fact that the organizations (B.I.C.C. and A.S.E.A.) on which it was depending for technical advice were as prospective suppliers, not disinterested parties, the Electricity Department sought the opinions of two user organisations, the Swedish State Power Board and the United Kingdom Central Electricity Authority. The former was unequivocal in saying that the guarantees on the conversion equipment could be accepted with confidence while the British group said it would be happier to see further experimental work done, though that for the valves of the across Channel system could be sufficient.
Evidence of the value of linking the power systems of the two islands was provided by a Ministry of Works hydrological study which showed that their water flows were complementary, which meant that the storage necessary in the combined system to cope with seasonal flow variations was less than that which would be required in total if the systems remained separate.
Thus from the view-point of the technologists from the power boards and the State Hydro-electricity Department the cable idea provided an economic and technically feasible way for the whole country to take advantage of the South Island’s large hydro resources.
In other circles the benefits were not so apparent.
Political Opposition Surfaces
From the time when Latta put his idea forward it engendered opposition. The matter was discussed by the Otago Expansion League at a meeting in October 1950 and became the subject of a leading article in the Evening Star, the afternoon paper in Dunedin, the centre where opposition to the link was to be strongest and last longest. The Star referred to lop-sided development in the two islands of New Zealand, and aggravation of this by the transmission of power north. Power was cheapest near the source of generation and in the Star‘s view it would be a shortsighted policy not to encourage rapid progress in the south, where four-fifths of the hydroelectric resources were. If it were to be sent north, a fair and proper method of doing this would be to make a differential charge, which allowed for the cost of transmission.
In the next few years the issue was stimulated by news that the technical problems of the proposed cross channel link between England and France were considered solved, and Canterbury manufacturers sought assurances that no action would be taken until a guaranteed surplus existed in the south.
As his successors would do, the incumbent president of the Electrical Supply Authorities Association pronounced on the cable, saying the idea was practical despite the Prime Minister, Mr. Holland, who represented a South Island seat, having said it was crazy. This interchange prompted the Evening Star to declare ’Cook Strait Power Idea Must be Fought’. The north could have geothermal power if it was any good.
The Prime Minister must have changed his mind for, less than a year later (in June 1955), we find the cable being referred to as one of his pet projects; to be started when Roxburgh, the much awaited answer to the south’s supply problems, had been commissioned. In Dunedin the Chamber of Commerce council became deadlocked on a motion that any surplus power should be used in the south.
Latta’s return from overseas, full of optimism about the project, prompted the Otago Daily Times to headline an editorial ”The Threat Draws Near” and to itself threaten the Government saying ”Before the Government takes action on the report it should understand the political issues involved”; South Islanders were said to regard the power reserves as a means of redressing the population and industry imbalance. A Times reader called its editorial ”manifestly narrow-minded and parochial.”
March 1956 was the month the Government commissioned the feasibility study by B.I.C.C. The Northern News, remarking on the astonishing speed with which the Government had moved, noted Mr. Goosman’s turnaround. In the House of Representatives the previous August he had said, ”personally, I have not got any faith in such a cable. It would cost a lot of money to try it.”
Mr. Davenport, the Electricity Department’s General Manager, told a conference that shortages could be expected until 1958, and expressed his belief that the cable would be approved, and Dr W M Hamilton, Director-General of the D.S.I.R. told the Wellington Economic Society the cable could have the advantage of delaying nuclear power twenty years. The Cook Strait weather made itself felt for the first time, delaying for a week a seismic survey by the Navy and geophysicists from the D.S.I.R. who were looking at the nature of the sea floor.
The cable question was back in the news in May, but the central issue was the freedom of the Broadcasting Service, then a Government Department. In a controversial move, a planned discussion on the Cook Strait power link, involving panels representing each island, was cancelled.
Asked to explain the censorship, R N Algie, the Minister of Broadcasting said he thought it unwise while the matter was being reviewed to stir up the question with outside discussion. In lawyers’ language, it is what you might call sub judice, he said. As criticism came in from all directions he must have wished he had not drawn this parallel for it did nothing to ease the situation.
Professor Davis, Dean of the University of Auckland law faculty challenged his interpretation of the phrase, saying it had no reference to purely administrative or policy decisions, which might be more satisfactory if they took account of the greatest amount of information and, if necessary, criticism.
It is not clear how the banning of the programme came about, but Mr. Algie may have been standing up for a decision made by the Director of Broadcasting at the request of the General Manager of the Electricity department. (ref The Press 3/5). Having become committed to the scheme themselves, the technologists may have feared the generation of opposition before they were in the position to put all their cards on the table with the publication of the B.I.C.C. report.
A hint of things to come was given by the Labour Party at its conference where a remit was adopted which opposed the cable unless South Island supply was assured for a long period and unless the power it delivered was substantially cheaper than alternative means of generation in the North Island.
In July 1956, the Southland Progress League heard Mr. Davenport tell them that if the cable were feasible it would bring forward the development of Lakes Manapouri and Te Anau. 1,000 megawatts could be generated at a cost, in unit terms, comparable to that from Roxburgh. The best place for the power station was 600 feet underground with tunnels taking the exit water out to Deep Cove. As the scheme would raise Manapouri 100 feet and Te Anau 5 feet, the Lands and Survey Department had been advised not to sell sections less than 100 feet above the existing level of Lake Manapouri.
At that time nuclear power was still glamorous and found a champion among academics, including Dr F.J. Farley, a physicist at Auckland University, who maintained that in reliability and cheapness it was superior to power from the South. The test of time would, of course, show that nuclear power had neither of these virtues.
Two sources which could be regarded as informed, the Minister himself and the ex General Manager of the Wellington City Council Electricity Department, R.S. Maunder, who had also been a member of the Power Planning Committee, independently gave clues that the principal feature of concern with respect to the reliability of the cable was the nature of the seabed: whether strong currents and rock along the cable route would cause it to wear through. The hydrographic ship and her attendant launches looking for the best track along the sea bottom had a testing time in the Strait:According to The Evening Post, "the Lieutenant and his eight man crew are collecting a choice list of descriptions of the Strait, the majority of them unprintable. Most of their troubles with tides, high winds, and rain which shrouds their marks, they are now ascribing to a gremlin named George…."
Geothermal Energy Competes
Towards the end of 1956 a Ministry of Works view began to emerge. The Commissioner of Works told the New Zealand Road Federation that geothermal steam
was so promising that it could fill the gap in the North Island demand for some years ahead, allowing more time for the thorough investigation of the difficult Cook Strait link. This was followed by unsourced reports from Wellington that a vast geothermal potential existed. In November the report prepared by the geothermal consultants (Merz and McLellan) with the backing of the Ministry of Works recommended a Stage II at Wairakei which would eventually take its installed capacity to 192 megawatts.
At the meetings of the Power Planning Committee in early 1957, the Ministry of Works strongly opposed an early start on the cable and the conflict was sufficiently great as to make the newspapers. Asked to comment, the Commissioner of Works talked of the need for a proper engineering appraisal of the project. "All we have now," he said, "is a report prepared by parties who may be interested in the construction". He was, however, quite happy to see work at Benmore commence. According to him Benmore need not be governed by the cable scheme. Benmore was, of course, for the most part a Ministry of Works project.
To a large degree this opposition to the cable in the Ministry of Works seems to have been based on self-interest.
Ministry of Works Self-Interest
Having built up geothermal expertise in constructing Wairakei and a North Island hydro construction force on the Waikato stations, the Ministry did not want to disband them. A reprieve was given on the geothermal side by the decision to expand Wairakei but the coming of the cable would signal the end of North Island hydro construction. The only new work in prospect was Aratiatia. The maintenance of the empire was always important in Ministry of Works thinking. Of course there can be valid reasons for doing this. If a construction team can move smoothly from one project to another, the social disturbance to the workforce can be minimized. The question that arises is: to what degree can economic arguments be ignored? And economics was not always to the forefront.
At the annual supply authorities Conference in October 1957 the Electric Supply Authorities Engineers’ institute was told by the supply authorities’ president, W.S.N. Rennie, that linking the islands would be one of the greatest things for the country. Meanwhile the South Island local territorial bodies at their conference found the cost startling, particularly when not one ounce of power would be produced. The money would be better spent establishing industry in the South Island.
Mr Arnold Nordmeyer, a leading member of the Labour opposition was reported to be unenthusiastic about the cable with its large capital cost (April).
The New Year saw the second Labour government in office. Work had started on Benmore but the rumours said there was a distinct possibility that the Labour administration would drop the cable plans. By April it was being said that financial stringency could lead to its deferment. The new Minister, Mr Hugh Watt, said that sterling expenditure must be reduced but that the trial cable would be laid. The Press pointed out that, without the cable, Benmore would be an expensive folly. Live Lines, the supply authorities’ journal, said the time had come for commission control of electricity supply and freedom from political control.
In May the specious argument was put forward by the Government that they were not prepared to spend £12 million that was not power producing and the need for a specially equipped ship to be brought across the world if a fault developed was raised. The Government were reported to be hoping that further power would be available in the North Island, obviating the need for a cable.
It is not clear how much the Labour administration’s dislike of the cable project was political and how much it was financial. Certainly export prices had dropped in 1957-58 and the Nash administration consistently displayed an unwillingness to increase overseas indebtedness.
Whatever the cause, the Government found an ally in the Ministry of Works who produced a long report for the Minister listing all its engineers’ doubts about the cable project.
The laying of the trial cable, which had been ordered before Labour came to power, went ahead, although not until the "Matai", which was laying it, had been kept harbour-bound for seven days waiting for the abatement of rough seas.
In August, Mr Watt announced that work on the cable scheme was to be deferred for a year, citing as the reason the need to conserve overseas funds. Two months later, he announced his own plans to meet future power demands, which had largely been formulated by the Ministry of Works and were signed by the Minister alone.
A further station was to be erected at Maraetai on the Waikato to provide peak power, replacing the gas-turbine plant proposed by the Combined Committee, and two further units were to be installed at Wairakei to make full use of the steam coming out of the ground. The Ministry of Works had got its reprieve.
In the House the ex-Minister, Mr Goosman, pointedly asked who had advised the Minister and said, "The people have put up with a lot in the past. There have been many shortages because of bad planning. We had got to a stage where everyone was agreed on what should be done, even Treasury, and along comes a Labour Government and the first thing they do is to ruin the plan."
At the annual Electrical Supply Authorities Association’s conference, the Minister had a hard time. The President, W.S. Rennie, saying there was no room for party politics in power development, alleged political bias and interdepartmental strife had played a considerable part in the Government’s sweeping changes to the previous administration’s power plan. Referring to the Commissioner of Works, Mr. Hanson, he said, "Repeatedly you will notice that some officials are more concerned with protecting their own empires than seeking advice on better methods of providing an improved and economic service."
The Government Knows Best
Attacking his critics, the Minister told them that it was the elected representatives of the people in Parliament who would govern the country and no one else outside it. As far as the amendment of the planning report was concerned, "Politics have never entered the subject".
Criticism of the new power planning proposals continued and in December the British firm of consulting engineers, Preece, Cardew and Ryder (PCR), were asked carry out an independent appraisal of the cable project. The New Zealand Herald, articulating North Island interests, said that by doing this the Government were reviving a project which should never have been shelved. The substitute project, the Tongariro scheme, which the Ministry of Works were trying to bring forward would be expensive and take a long time to construct.
Dr T. Hagyard of the chemical engineering faculty at the University of Canterbury, a keen exponent of electrochemical processing, told the South Island Chambers of Commerce that New Zealand was unwise to hoard its power resources as they could provide an advantage in the manufacture of calcium carbide, phosphorus, concentrated phosphate fertiliser, and aluminium. The Otago Development Council tried to attract the Commonwealth Aluminium Company (now Comalco) to build a bauxite industry, and a geologist, Mr Harry Evans, representing the company, visited the Dusky Sound region to look for cheap power sources. Mr Evans, a New Zealander, had been responsible for finding the vast bauxite source at Weipa in North Queensland. (The refinery was ultimately established at Gladstone in Queensland).
There was talk of the potential of Wairakei having been over-estimated and the engineer chosen by PC&R to carry out the cable study was prevented by bad weather from getting the data he sought on Cook Strait.
Mr K.J. Holyoake, Leader of the Opposition, said the cable should go ahead but the Wellington Evening Post, which seemed all through the currency of the issue to have a direct line to the Ministry of Works, said that the successful operation of Wairakei had changed the picture.
The building of Benmore continued and in November it was reported that the consultants’ report on the cable had been received but its findings were not made public. Mr Holyoake said that the Government policy on the cable was indistinguishable from deliberate obstruction.
Finally in April 1960, the report was released and proved entirely favourable, rejecting the objections that had been raised by the Ministry of Works. That this should have happened is not entirely surprising, since what Preece Cardew and Ryder had done was to rely largely on what had already been done by the Electricity Department and re-present it with comment.
With the release of the report Mr Watt said that he would tell parliament of his decision during the coming session but no decision had been made by the end of the year when the cables were laid a thousand yards apart to facilitate repairs. Although each took only about a day to lay, the total process took over five weeks because of the generally bad weather and sea conditions.
Despite the occurrence of a fault, which required that one of the cables be raised and a new section jointed in, the project was completed within budget and on schedule in May 1965.
An Ambitious Scheme
At the time of its commissioning the link was by far the most ambitious high voltage direct current scheme in the western world. From its commissioning until March 1983, it had provided 24 percent of the North Island electricity demand, with this figure growing to over 30 percent for the last five years of the period.
Its success has been such that a duplicate scheme has been built, although improved technology led to the mercury-arc valves being replaced by solid-state thyristor devices.
An extensive series of papers published in New Zealand Engineering in 1965 and 1966 describe the engineering of the scheme.
Peter Taylor’s book "White Diamonds North", published by Transpower, 1990, covers the first 25 years of the operation of the DC Link.