KEY POINTS:
A power company is calling for submissions on its plans to generate electricity by harnessing the tidal power of Kaipara Harbour.
Crest Energy has applied to Northland Regional Council for resource consent to set 200 turbines in the main channel of the Kaipara Harbour entrance, and has invited public submissions.
The turbines are to be linked by a sea-floor cable to a proposed substation at the Hoteo River near two existing transmission lines.
The plans would see electricity generated for 250,000 homes, or 200MW, by harnessing about 2.5 per cent of the harbour's tidal flows.
Crest Energy executive director Anthony Bellve said tidal power was environmentally sound and a similar project off the coast of Devon, England, had been successfully generating electricity for the past three years.
"We have tried to mitigate every possible environmental effect," he said.
"This is invisible, silent and totally lacking in electromagnetic force emissions and not detrimental to any form of life - that's very important," said Mr Bellve.
The company has been in talks with local iwi Ngati Whatua and Te Uri o Hau, and its application to use the Kaipara resources for the next 35 years is to be heard by a joint commission of the Northland and Auckland Regional Councils and Rodney District Council in mid-February next year.
At 22m high and with a six second rotation, Mr Bellve said the turbines posed little if any risk to marine life.
"They're very large with a compression wave moving in front of it which will push fish aside but dolphins are likely to play with them."
Mr Bellve said the rotors were protected by a venturi shroud and the DC cables running from the turbines were shielded and buried to minimise electromagnetic transmissions.
He said the turbines would not rust and were likely to be made of graphites and plastics, with the legs made of steel and the foundations made of concrete.
"Anything under the surface sunk down deep in the water does not corrode - you need oxygen for that," said Mr Bellve.
The main structure of the turbine was expected to last at least 35 years, with servicing every four years.
Public submissions on the proposal will close in January.
