April 7, 2008
New Zealand

Power line limits 'may restrict' Kaiwera wind farm

Major electricity generator Contact Energy Ltd has warned national grid transmission lines would be unable to cope with the extra electricity produced by the Kaiwera Downs wind farm and other wind farm projects planned for the south.

The complexities of electricity generation and marketing took up much of yesterday as the Gore District Council-Environment Southland joint resource consent hearing for the wind farm, near Mataura, entered its second week.

Contact Energy says it supports the consent application from its competing electricity generator and Kaiwera Downs backer, TrustPower.

However, it does not want TrustPower to feed electricity from its turbines into the national grid until transmission lines were upgraded to cope with the extra load.

Contact Energy market and dispatch manager Boyd Brinsdon conceded he did not know when or even if that would happen.

A feature of the South Island system was that installed generating capacity in Otago and Southland significantly exceeded local demand, making the area a major exporter of power, he said.

The three 220kV circuits that carry electricity north to the Waitaki Valley, were, at times, already at capacity, while there were constraints on the Cook Strait high-voltage cable, Mr Brinsdon said.

Contact Energy has also argued transmission limitations for its rivals’ Mahinerangi and Project Hayes wind farms which were granted consent late last year. It has lodged appeals against both with the Environment Court.

Contact Energy legal counsel Susan Newell said if Kaiwera Downs and other wind farms came on stream, it would adversely affect hydro-generation plants.

Should these plants be stopped from feeding into the national grid because wind farm-generated electricity was dispatched first and put transmission lines at capacity, water would have to be spilled from the limited hydro storage ponds.

This was a waste of a renewable energy source, she said.

If the end result of new wind generation from Kaiwera Downs was just to substitute existing renewable generation, such as hydro, then there was no contribution to meeting electricity demand or reducing greenhouse gas emissions, Ms Newell said.

Meanwhile, the hearing panel was advised of revised consent conditions, relating to noise, worked out between the council’s noise expert Nigel Lloyd and TrustPower’s consultant Nevil Hegley.

Mr Lloyd said the maximum noise level, when the turbines were operational, should be lifted 5dBA to 40dBA from his original recommendation.

The exceptions were two houses on the downwind side or east of the wind farm. The maximum level at the Alexander and Blakely homes should stay at 35dBA, he said.

The hearing continues today with Kaiwera residents opposed to the project having their say.

By Sonia Gerken