Power to the Kaipara

CREST OF THE WAVE: Conditional approval has been given to Crest Energy to go ahead with its $600 million plan to put 200 tidal power turbines on the seabed at the mouth of the Kaipara Harbour.

The Environment Court has given Crest Energy the nod to put up to 200 tidal power turbines on the seabed at the Kaipara Harbour mouth with a positive recommendation to Conservation Minister Tim Groser on the proposal.

The endorsement is subject to the satisfactory resolution of outstanding issues including provisions to ensure the safety of the endangered maui dolphin and the important snapper fishery on the west coast of the North Island. The court also sought details of an environmental monitoring plan.

The company had previously been granted resource consent for 35 years by the Northland Regional Council to harness the power of the tidal flows into and out of the harbour, a decision that was appealed to the Environment Court.

Crest estimates its plans could eventually generate up to 200MW of electricity, enough to power 250,000 homes.

The initial capital requirement is estimated to be about $40 million, with costs over the four stage installation expected to run to about $600 million. Modest revenue is expected from 20 turbines within five years.

"Tidal power is predictable, sustainable, silent and invisible. These advantages need to remain the focus, rather than the eight hours a day when tidal turbines produce little or no power," Crest Energy director Anthony Hopkins says.

"Tidal power complements other energy sources and will, eventually, be of importance to maritime countries."

Each turbine is 24 metres high but would be seven metres underwater at low tide.

The total annual revenue when fully operational
will be as high as $100 million at current wholesale rates.

Most of the funding for the scheme is expected to come via Crest’s new partner, Wellington-based Todd Energy, which has taken a 35 percent stake in the company with an option to lift that to 45 percent.

Todd Energy generation development manager Tim Cosgrove says the use of tidal power is in its infancy internationally.

"There are not many looking at large scale projects like we are at the moment. An emissions
trading scheme would also make tidal power more attractive," he says.

But tidal power is a huge resource in New Zealand, and the technology would improve as it
had for wind turbines in the past decade, he says.

Todd Energy managing director Richard Tweedie says its decision to become a significant share-holder is a sign of confidence in both Crest Energy and its Northland tidal project.

"We will also be at the forefront of developing a commercial tidal plant in a worldwide context."

The Kaipara is among the largest enclosed harbours in the world, covering 900 square kilometres with a perimeter of 612km.

Crest says it is one of the best sites in the world to generate substantial amounts of electricity.

Large ships do not use the harbour.

About eight billion cubic metres of water pass in and out of the harbour daily.

Tidal turbines follow similar principles to wind turbines, except that it is possible to forecast the tides and therefore both the level of generation and the time of day for production of power.

There are about 10 companies seriously constructing tidal turbines worldwide, and others with big balance sheets like Seimens are starting to join the industry, mainly from northern Europe and North America.

Since seawater is 830 times denser than air, the same flow generates several hundred times more power in water than in air.

Another advantage is that tidal turbines are totally submerged, invisible and silent.