Last week, on 18th March 2011, New Zealand’s Minister of Conservation Kate Wilkinson, granted approval to Crest Energy for the staged installation of up to 200 fully submerged tidal turbine power generators in the Kaipara Harbour.
This is the largest fully submerged tidal turbine proposal in the world. To date only small arrays of tidal turbines are used or trialled in Scotland, France and America.
The Kaipara Harbour is the second largest harbour in the southern hemisphere and is located on New Zealand’s west coast, about 50km north of Auckland.
After years of local opposition, New Zealand company, Crest Energy was granted consent for the $600 million tidal turbine project as a restricted coastal activity under the Resource Management Act.
In February, the Environment Court ruled that the renewable energy project (with an installed capacity of around 200MW), could proceed with a number of conditions.
Turbine project gains final consents
“The Environment Court carefully studied the project and I agree with its report,” Ms Wilkinson says. “This is the first large-scale commercial approval for tidal power generation and it has the potential to play a significant role in the development of a new source of renewable energy in New Zealand.”
The potential environmental impacts of the development were carefully worked through during a robust four-year consent process, during which the Department of Conservation had its concerns addressed in the Environment Court, she said.
Submissions opposing the tidal turbine project were concerned with the impact on the inner harbour, particularly on sedimentation, sand movement dynamics, adverse effects on the harbour snapper nursery, and coastal erosion.
Environmental impacts will be monitored
“I am aware of concerns raised by submitters and believe the conditions set out would ensure any possible negative impacts can be properly monitored and accounted for,” said Ms Wilkinson.
A publicly notified review process would occur after each stage of installation and the development could be halted – and turbines ordered to be removed - if significant environmental impacts were detected.
The installation of the turbines would be deliberately staged as part of an approach to allow for ongoing monitoring of effects, clear reporting and enforceable consent conditions. The first installation would involve three turbines, she said.
Northland Regional Council will be responsible for monitoring the environmental impact on a wide range of marine wildlife such as sharks, rays, marine mammals and fish, including snapper.
Electricity generation for Northland
If fully implemented, the tidal turbine project could generate enough electricity to power the whole region from Albany (north of Auckland) to Cape Reinga (northern tip of Northland), using existing transmission lines.
The Kaipara Harbour is one of the largest harbours in the world covering 900 square kilometres with 3,000 kilometres of shoreline and extends for 60 kilometres from north to south.
Crest Energy said the tidal turbines have similar principles to wind turbines, except that it was possible to forecast the tides and therefore both the level of generation and the time of day for production of power. As the tidal turbines would be totally submerged they were invisible and silent.
There were about ten companies constructing tidal turbines and others joining the industry, mainly from northern Europe and North America, but this is the largest consented project.
Huge tidal flow makes project possible
Up to 8,000 million cubic metres of water pass in and out of the Kaipara Harbour each day, on tides that average a 2.10 metre range, making it particularly suitable for generating flow for tidal turbines. The harbour is rarely used for shipping due to the treacherous tides and sand bars at its mouth.
The company estimated total costs for the project over the first ten years were about NZ$600 million, offset by modest but growing revenues from year three.
Local opposition to the proposal remains vocal with both the region’s hapu organisation Te Uri o Hau, and the Mayor of Dargaville (the nearest large town to the project site), vowing to continue to oppose the development.
A public meeting in Dargaville last week voted to fight on after Maori hapu Te Uri o Hau lost its’ court bid to stop the tidal power station. Kaipara Mayor Neil Tiller told the meeting he was opposed, because the technology was largely untried and there was a risk to marine life and the harbour. South Kaipara people are planning similar public meetings this month.
