Bryan Leyland: We can still avoid towering mistakes

Auckland and Northland use more than 1900 megawatts of electricity - 30 per cent of New Zealand's total demand. On hot days and cold nights the transmission system is stretched to its limits to keep the lights on. Transpower has decided that building a 400kV transmission system is the best way of securing the supply. Other options do exist but under the present industry structure they cannot be considered.

The proposed 400kV system is needed because of past neglect. Ten years ago, Transpower could have taken two old 220kV lines out of service and up-rated them to give an extra 1000MW of transmission capacity. It didn't because the Resource Management Act and the Electricity Act made it almost impossible to build or upgrade transmission lines.

Transpower failed to do what it should have done - lobby the government to make the legislative changes needed to increase our transmission capacity by uprating existing lines and building more.

Because the management was convinced that lots of small power plants would sprout up all over the place and reduce the load on the transmission system, it didn't lobby the government and a golden opportunity was lost. For reasons that were obvious at the time these small power plants didn't take off and we are left with a seriously overloaded transmission system.

The new chief executive of Transpower, Dr Ralph Craven, soon discovered that the lines supplying Auckland were heavily loaded and it was too late to up-rate the two oldest lines. New lines were needed and Transpower's decision to build 400kV lines that can transmit three to four times as much power as any of the existing lines was logical.

The 400kV proposal has attracted strong opposition. Opponents want the lines to be run underground or along the river, and claim there are risks from electro-magnetic radiation. If the only option was underground or along the river, the cost would increase by a factor of 10 and the line would never be built.

Regarding electro-magnetic radiation, the objectors can be absolutely sure, first, that if there is an effect, it is something like smoking one cigarette in a lifetime, and, second, that the levels of radiation from appliances, electric blankets, magnetic bed underlays and the like in their own homes are higher.

Millions of dollars spent on research has failed to prove there is a connection between power lines and health. Doubt exists only because it is impossible to prove there is absolutely no risk. Life has always been risky. A rational society spends its money on mitigating the highest risks.

In an ideal world, the transmission problem would have been recognised 10 years ago, the legislation would have been changed, and the two 220kV transmission lines would have been upgraded to transmit an extra 1200MW.

In addition, the Whirinaki reserve station would have been sited at Marsden Pt and the combined-cycle station now being built at Huntly would have been built at Otahuhu. If all this had been done, the need to build the 400kV line would have been deferred for many years. But, in our real world, the laws, regulations and electricity market do not provide the incentives that would make such obviously sensible things happen.

But it is never too late to mend matters. If we plan long term, with a reliable and economic supply as our main objective, we can delay, and possibly avoid, the need for the 400kV system.

It would not be difficult to increase the generating capacity in Auckland and Northland. This would reduce the load on the transmission lines coming from the south.

Here is what could be done. Two old 55MW gas turbine generators at the Otahuhu power station could be fitted with new jet engines to provide 110MW. An additional 40MW or more could be obtained from a third gas turbine at the Southdown power station.

This would give us an extra 150 extra megawatts and would defer the 400kV line by two or three years.

If we want to upgrade the old 220kV lines, more power is needed. The mothballed 250MW Marsden B station could be recommissioned, running on oil to support the system when the load was high. A 400MW combined-cycle station could be built at Otahuhu. If short of gas in the early stages, it could "borrow" gas from Huntly or the Stratford combined-cycle station. This station would run most of the time and so provide continuous system support.

Another option is to shift the Whirinaki gas turbines from Hawkes Bay to Marsden Pt, where they would support the supply to the north and be assured of a good supply of fuel when they needed to run continuously during a drought.

If all these things were done, the load on the transmission lines feeding Auckland from the south would be reduced by about 950MW. This would defer the need for the 400kV upgrade by 15 years or so and give us time to consider other options.

These include:

* A large coal-fired station in the South Island with a new 2000MW direct current link all the way to Auckland (using an existing 110kV line route).

* Bringing one pole of the existing DC link through to the north of Auckland.

* An 1800MW nuclear power station north of Auckland that would make a huge reduction in the amount of power needed from the south.

* Effective energy-efficient programmes that would have time to produce results.

All this requires long-term planning and the overall co-ordination of generation and transmission.

Under the present regime, this could only be done by heavy-handed intervention in the market by the Electricity Commission.

Although the Government has already intervened in the market by accepting responsibility for reserve generation and by supporting the construction of the combined-cycle station at Huntly, the new plan would hand new powers to the Electricity Commission so it could intervene on a scale that would end any pretence of real competition.

The best way of achieving this desirable end is to accept that the existing market model is a failure and change to a model that encourages long-term planning and optimal co-ordination of generation and transmission and exploits the real competition that exists in the international market for the construction and operation of power stations.

* Bryan Leyland is an Auckland power-industry consultant.