Tidal power - Crest Energy

How did this all start?
What are the differences between the 2006 and 2007 RMA applications?
Can I see a map?
What's the timetable?
What are the risks in this project?
Will the project attract government support?
Why the Kaipara and not other harbours?
How will the project be monitored?
How does tidal energy compared with other energy sources?
How big is the Crest Kaipara Energy Project?
Will the project create jobs in New Zealand?
How do I register as a supplier to Crest Energy?
Can I get a job at Crest Energy?
How do the currents go in and out of the harbour?
Will the turbines get covered in barnacles?
How will the turbines be kept in position?
Will the turbines rust quickly in sea water?
If the turbines are seven metres underwater, can a storm destroy them?
Where are the 100 shipwrecks?
Will the turbines damage dolphins?
Will the turbines damage birds?
Will the project harm fishing?
Will the turbines prevent access to leisure craft?
Will the cables cause problems anchoring, or to animals?
What happens if the main channel changes?
What happens if the cables break?
Why do the turbines need so much space?
What is resource consent?
How will the turbines be kept in place on the harbour floor?
Where can I find statistical and factual information?
What is the difference between megawatts and magawatt-hours?
How much electricity can one marine turbine produce?
What happens when the tide is slack and not moving?
Can I buy 'green', renewable electricity for home?
Why use DC power (rather than AC)?
What sort of cable will be used?
Why do you need a substation?
What happens to the turbines if the project fails?
Who are the main generators in New Zealand?
Are these turbines viable?
How do electricity prices in New Zealand compare internationally?
How do tides work?

How did this all start?

The company was founded in July 2005. But the idea is not new: the Auckland Chamber of Commerce unsuccessfully lobbied for tidal power in the 1920's (“Auckland’s Voice of Business: A history of the Auckland Chamber of Commerce 1856-2006” chapter 3 page 51).

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What are the differences between the July 2006 and July 2007 RMA applications?

Old applications relating to the cross-harbour 30 kms cable route terminating at the Hoteo River, and the proposed substation in Rodney, were withdrawn and superceded by an application to terminate the submarine cable at the Pouto Point on North Head. In addition the project is now staged with detailed monitoring at each stage. The Slide show has details of the planned stages and terrestrial reticulation.

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Can I see a map?

A quick way to get an overview of the project is with our Slides. For photographs, maps and diagrams, please see our Gallery.

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What's the timetable?

July 2005

Company incorporated

July 2006

First applications for permits

December 2006

Public submissions for and against the Kaipara project given to Northland Regional Council, Auckland Regional Council and Rodney District Council.

January 2007

Public submissions closed on 12th January 2007
Council officers review application material and submissions received
Council officers review application material and submissions received
Crest Energy provides any further information requested by Council officers (these are called S92s; a previous round of queries were answered in early November and are available on our website in the Consents section)

July 2007

CREST provides further s92 information requested by Council officers
Crest Energy applies for additional consents in response to public submissions received in January 2007.
The revised applications require less marine cabling (7 kms vs 33 kms), occupy less space in the harbour (350 hectares vs 1,300 hectares) and place turbines deeper below the surface of the sea (7 metres vs 5 metres).
The new applications also mean that previous applications with Rodney District Council and the Auckland Regional Council are no longer required.

September 2007

Public submissions to the applications closed on 21st September 2007

October 2007

Northland Regional Council begin writing the Staff Report, a detailed consideration of the Project
NRC assess candidates for the role of Commissioners. Three independent Commissioners form a panel to consider the evidence for and against the applications

May 2008

Hearings ended 30th May 2008 and were held near Whangarei for five days, with one day spent at Waikaretu marae, Pouto, on the North Head of the Kaipara Harbour. The welcome, singing, lunch and proceedings at the marae were special. The Commissioners and Maori elders took a helicopter ride over the harbour.
August 2008

In early August the NRC and Commissioners requested an extension to 22nd August 2008, which Crest granted.

The Northland Regional Council recommends that the Minister of Conservation approve a staged tidal power plant in the Kaipara Harbour on 21st August 2008.
September 2008

Two parties have launched appeals to the Environment Court requesting the project be declined in its entity. Two further appeals centre around individual conditions rather than objections to the entire project.

We await An Environment Court hearing date.
Environment Court proceedings could last two weeks, with the Court’s recommendation forwarded to the Minister of Conservation
The Minister makes a decision for or against the project

Q1/2 2009

If ministerial decision is in favour of Crest’s applications, Crest raises pre-construction capital via one or more possible mechanisms

2009-2011

The total funding requirement is over ten years is perhaps NZ$ 600 million, offset by modest but growing revenues from the sale of electricity from 2010
Capital will be raised in stages corresponding to project milestones
Full generation of up to 200 MW is planned for 2015

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What are the risks in this project?

The risks are similar to any major project. Additional considerations for the Crest Kaipara Energy Project are:

Political: will consents be granted by the authorities on viable terms?
Technical: will the combinations of turbines and cables work to specification?
Financial: will Crest Energy secure sufficient capital to execute the project?
Management: will Crest Energy attract the right people to complete the project?

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Will the project attract government assistance?

Yes.

Prime Minister Helen Clark launched the New Zealand Energy Strategy which includes a target to generate 90% of electricity from renewable resources by 2025, and to limit the construction of new fossil fuel generation plants for a decade. Current renewable output is about 60% of supply. There is limited scope for further large scale hydroelectric power generation. Geothermal and wind are well positioned and newer technologies such as wave and tidal were mentioned by the government: Crest Energy is named in the announcements. Meanwhile NZ Maui gas supplies used for electricity generation are running out and an alternative, the importation of LPG, would be even more expensive than renewables, according to Ministers.

A particular issue for northern NZ is that most electricity supply flows from south to north, and through the Auckland isthmus. The government has stated that it does not support a proposed gas plant north of Auckland near Helensville, close to Kaipara Harbour. Although there are many small initiatives to generate electricity north of Auckland, at this stage it would seem the Crest project may be valuable both for grid stability and security of supply to the north, once and if it comes on stream.

The Emissions Trading Scheme is good news for the Project. It may mean that the spot market electricity price line rises by about 10% over time. In addition Crest may provide VER's which are likely to trade at a discount to Kyoto carbon credits.

In May 2008 Crest Energy was awarded NZ$1.85 million from the New Zealand Marine Energy Deployment Fund (185 KB) by the Energy Minister. The NZ Energy Efficiency and Conservation Authority (EECA) administer the fund on behalf of the Minister of Energy. The award is subject to the granting of resource consents for the project. The NZMEDF runs for four years and offers a maximum of NZ$ 8 million: the award to Crest is the maximum available in the first year.

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How will the project be monitored?

Monitoring is an important component of the Project. Monitoring data would be evaluated by the Consent Authority under the auspices of RMA s128 review before each stage of the project. A draft monitoring plan is currently with the Department of Conservation Whangarei office for comment and detailed discussions are in progress.

Baseline data would be collected prior to the Stage 1 deployment, followed by a period of monitoring during installation, with monitoring covering a total of twelve months prior to initiation of Stage 2. A similar process would be apply for transition from Stage 2 to 3 and from Stage 3 to 4.

Monitoring before, during and after installation of the various stages would allow verification of the level of actual environmental effect, would enable adverse effects to be determined and would provide a basis for measures to avoid, remedy or mitigate any such adverse effects as appropriate.

Monitoring will include a wide range of environmental parameters and monitoring of the integrity of the turbine structures themselves. Specific aspects to be monitored will include:

Energy extraction through the tidal current devices
Interactions with tidal flow patterns, localised currents, sedimentation processes and seabed bathymetry and morphology
Effects of support structures on the wave and tidal dynamics, possible implications for local sedimentation and seabed movement, geotechnical and geological aspects
Effects of the rotor interactions on the water column and the subsequent effects on seabed morphology
Observed collision risk for marine life
Acoustic emissions and the potential implications involved with respect to marine mammals and other marine ecology, such as fish
Vibration characteristics
Overall ecological impacts and benefits of installation and operation – direct seabed disturbance, artificial reef effects
Recreational, commercial and non-commercial use of the harbour

Detailed monitoring protocols will be defined in a monitoring plan to be developed in consultation with stakeholders and the Consent Authority.

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Why the Kaipara and not other harbours?

The Kaipara Harbour has the biggest tidal flows in New Zealand and is one of the largest harbours in the world. During spring tides the current in the Kaipara can exceed 9 kph (nearly five knots).

The next four New Zealand harbours are Manukau, Hokianga, Whangarei and Waitemata. The Kaipara has over double the tidal flow of Manukau. Additional attractions of the Kaipara are the lack of commercial shipping, proximity to Auckland north of the isthmus, and relatively low leisure usage of the harbour mouth.

The depth of the harbour mouth channel, where the turbines will be located, is an asset: neither too deep for access by divers if needed (31 mts to a maximum 52 mts), nor too shallow and therefore impacted by lack of water at low tide. The sandbar surrounding the mouth protects the project from oceanic waves.

Harbour	Water volume	Average current
	Millions of cubic metres	Metres/second	Kilometres/hour	Knots
Kaipara	1,990	1.12	4.0	2.20
Manukau	918	0.92	3.3	1.80
Hokianga	228	0.81	2.9	1.60
Whangarei	164	0.54	1.9	1.00
Raglan	46	0.59	2.1	1.10

Hume and Herdendorf, 1992, 1993; and Hicks and Hume (1996)

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How big is the Crest Kaipara Energy Project?

Crest's output would provide power for the equivalent of 250,000 NZ homes. Crest aims to generate about 3% of New Zealand's industrial, commercial and residential electricity needs. Demand is expected to rise 2% annually across the country and 5% or more north of Auckland.

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How does tidal power compare with other energy sources?

From an ecological and carbon emissions viewpoint, tidal power looks healthy. Although a study commissioned by Crest concerning the lifetime carbon footprint including construction of tidal energy as compared other sustainable energy sources in the NZ environment is not yet complete, early indications are that the footprint sequence is possibly hydro, tidal, wind and finally geothermal.

Clearly all four of the sustainable energy sources in the study have much lower carbon footprints that conventional fossil fuel generation plants.

Tidal seems to just come ahead of wind because the electricity output is more consistent, and because wind turbines need to be very robust to withstand violent gusts and sudden changes in wind direction.

Tidal energy short and long term marginal costs seem economically similar to wind power.

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Will the project create jobs in New Zealand?

General averages suggest that large projects create jobs locally, nationally and internationally in roughly equal proportions. The Crest project could involve NZ$600 million of expenditure over the first ten years of the project.

Figures from the Industry Capability Network, part of NZ Trade and Enterprise, suggest that eleven jobs are created by each NZ$ million invested. Furthermore government expenditure on unemployment benefit declines by NZ$118,000, governnment income tax revenue increases by NZ$117,000 and there is an increase in purchasing power of $195,000.

At present Crest's plans for roles include:

Monitoring	Several phases of detailed biological and environmental monitoring of the site before, during and after construction
Depot	Turbine fabrication and assembly, land-based maintenance, docking for marine craft
Materials	Steel, cables, composites, ballast, concrete, electrical equipment, marine equipment, barges and boats
Crews	Fabrication, assembly, installation, commissioning, maintenance and monitoring of equipment offshore and on land
Substation	Construction, commissioning, operation and maintenance; transformer, converter and cooling equipment
Cable	Trenching, installation, commissioning and maintenance
Markers	Installation and maintenance of navigational markers
Scoping	Professional services for the scoping of the project
Core team	Provision of support for the day-to-day operation of the project

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How do I register as a supplier to Crest Energy?

Crest Energy is not yet ready to talk with potential suppliers.

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Can I get a job at Crest Energy?

Not yet.

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How do the currents go in and out of the harbour?

Detailed current measurements using GPS drogues show a number of different flows in the Kaipara depending upon the tidal cycle (spring to neap). The flow is asymetric meaning that the ebb and flood are not identical in direction. The tidal current varies between 1.6 and 2.5 metres per second (up to nine kilometres per hour or five knots). The areas of strongest current are on the western side of the harbour mouth.

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Will the turbines get covered in barnacles?

The tidal current varies between 1.6 and 2.5 metres per second (up to nine kilometres per hour or five knots). The seawater carries sand particles in suspension from harbours and rivers south of the Kaipara, which is why there are huge sandhills and sand extraction activities around the Kaipara. The sand will help keep the turbines clean and reduce biofouling. Sand falls out of the water flow and form deposits when the current drops below 0.3 metres per second suggesting that the turbines will not suffer from sand sedimentation around them. The photo shows how much sand there is (the dunes are about 120 metres or 400 feet tall)!

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How will the turbines be kept in position?

There is a firm footing for turbines in the harbour mouth. Side sonar scans, CCTV video footage, dredge samples and samples taken from the harbour floor in the turbine area by commercial divers suggest the floor is very hard and made up of either bare scoured sandstone, or densely packed large grain sand on a bed of sandstone. The divers used a water pump and lance, sheer vane gauge and hand penetrometer to asses the nature of the harbour floor. The divers also noted that visibility is extremily poor in the channel.

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Will the turbines rust rapidly in sea water?

All materials corrode to varying degrees. A highly corrosive combination is air (oxygen) and sea water. Our turbines are submerged with much less oxygen than in air, which should give them a long life. Crest estimates parts of the turbines will need replacement each decade and that the turbines will be subject to a regular maintenance and monitoring programme.

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Will the turbines damage dolphins?

Turbine rotors turn slowly to a maximum of six revolutions a minute and are shielded. The speed of the rotors depends upon the speed of the current and the pitch of the turbine blades. A turbine with a blade radius of nine metres has a space between successive rotating blade tips of about 11 meters. Marine mammals and fish sense and avoid obstacles (Southern Right whale, NZ sea lion, orca and dolphin). Dolphins are agile, communicative, have excellent eye sight and echolocation. Crest believes the risks are minimal for dolphins. The turbines will provide new areas for fish and other life in the harbour mouth. Sharks, rays and skates are also important and although many people think they are slow and unresponsive, they show remarkable agility and power to move fast when necessary.

The Openhydro turbine is almost silent and should not, therefore, distract animals from their travels, particularly bearing in mind the high baseline noise from the sandbars surrounding the harbour mouth.

See the NZ Department of Conservation guide to marine mammals for more information, and the NZ Enclyclopedia which covers sharks, rays and skates.

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Will the project damage birds?

Huge numbers of wading, migratory and resident birds live in and around the harbour. The cables are sited to avoid sensitive areas such as seagrass (eelgrass) beds and tubeworms habitats. Away from the main channel the cables will be in sand and buried. The turbines may in fact increase the supply of fish for birds by providing fish breeding sanctuaries in the slower water at the base of the turbines. The panorama photo below contains thousands of wading birds.

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Will the project harm fishing?

There is a rumour circulating that fishing from the shore, and fishing in the harbour, will be banned: this is not true.

Consultations indicates that a key fishing area is around the mussel beds in known as the Graveyard, presumably named because of the many shipwrecks in the area. Crest Energy side-scan sonar surveys identified the location of the mussel beds and nature of seabed in the turbine array area. The turbines will be located to greater than 31 metres depth which provides separation from mussel beds, and avoids primary areas of fishing use.

Longer term Crest Energy do not think the project will reduce the enjoyment of anglers. Consultations suggest that the area of the turbines is seldom used for fishing, even at slack water due to the depth of the channel of up to 50 metres. During ebb and flood water the turbine area is dangerous and anchoring difficult for leisure craft. The fishing that does take place near the turbine area is sited closer to the shore, or further out to sea.

A significant point to note is the differences between the old and new RMA applications made in response to concerns expressed in public submissions to the project up until 12th January 2007. The original outlined a cable running east-west across the harbour for over 30 kms, whereas the new route is about 7 kms from the array area to Pouto Point. This enormously reduces the footprint of the Project and the level of impact on fishing activities.

There is siginficant evidence from similar structures used in offshore oil and gas fields to suggest that fish stocks and bio-diversity will be improved by the presence artificial sanctuaries. In other words, over several years Crest believes the turbines will make a significant and positive contribution to the health of the Kaipara harbour.

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Will the cables cause problems anchoring, or to animals?

The Kaipara is over 900 square kilometres and Crest Energy has applied to occupy a tiny fraction of the area. A pair of cables will run seven kilometres from the harbour mouth to Pouto Point on North head. They will be buried over one metre below the harbour floor, usually in sand. Leisure craft will be able to anchor over the cable but will be probably be restricted from anchoring in the turbine area. The cables are both buried and shielded. Similar cables are used all over the world.

The cables will carry DC electricity which is important since the electromagnetic interference is 5% of the impact for AC. Sharks, rays and skates are particularly sensitive to high electromagnetic levels. The burial process itself will cause short term disruption to harbour floor animals and plants. The cables are about 125 millimetres in diameter.

A second type much smaller cabling will link the turbines together and join with the main submarine cable at one or more hubs. Each array or loop will manage between 10 and 30 turbines.

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What happens if the main channel changes?

Early European maritime charts date from the middle of the 19th century. The main channel through the harbour mouth, where Crest plans to place turbines, does not appear to have moved in 150 years. Although the sandbars clearly shift, their overall position has not changed.

The cables include a fibre optic strand. Changes in pressure and tension can be measured accurately and Crest will be alerted quickly to movements on the harbour floor, and issues with the cables. In this event Crest can either move the cables and bury them elsewhere, or cover them with harmless ballast, or use a kind of blanket to shield the eroded area. The marine chart below shows the main channels.

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What happens if the cables break?

The cables are buried over one metre below the harbour floor in sand. If the cables are broken, as has happened for a variety of reasons with other marine cables, repair should take 48 hours.

Locating the break is done using feedback from the fibre optic strand in the cable which measures changes in tension and pressure. Weather conditions inside the Kaipara do not present additional hazards such as ice and large waves.

The most common insurance claim by offshore wind farms in Europe is for cable damage caused usually by commercial vessels. The Kaipara harbour has very limited commercial vessel activity confined to sand mining barges on the eastern edge of the harbour.

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Will the turbines prevent access to leisure craft?

The turbines will be positioned seven metres below low water (about 24 feet), meaning that leisure craft can pass freely over the turbines at all times. The harbour mouth is nearly six kilometres wide and the turbines will occupy a small percentage of the width.

The turbines will be limited to the 31 metre contour of the deep water channel, and below. Commercial traffic, apart from sand barges, is minimal due to the dangerous sandbars at the harbour mouth and the low population of the catchment area. The sandbars outside the harbour mouth offers about five metres draught at low tide: few large craft are likely to attempt to enter the harbour.

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If the turbines are seven metres underwater, can a storm destroy them?

The prevailing weather on the Tasman is from the south west and very large storms are common. However the turbines are protected by the sandbars that surround the harbour mouth. The sandbars limit navigation to vessels with well under five metres draught. Many parts of the sandbars are exposed at low tide.

There are over 100 documented shipwrecks around the sandbars. The area in which Crest will install turbines is calmer with the largest waves at about 1.50 metres. The first photograph below is unusual since the waves were created by the current (standing waves), and not by the action of wind or waves from out to sea.

Conditions in the harbour mouth can be very dangerous for smaller craft in particular when high winds blow in the opposite direction to the tidal flow, causing choppy seas that can flood a small boat.

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Where are the shipwrecks?

The Kaipara, like many harbours around New Zealand, is hazardous for shipping. According to Maritime New Zealand there are three types of harbour bar - dangerous, very dangerous and lethal - the Kaipara Harbour is no exception.

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What is the difference between megawatts (MW) and megawatt-hours (MWh)?

A watt is the unit rate at which work is done in an electrical circuit. A light bulb typically has a power requirement of 100 Watts.

kilo watt (kW) = 1,000 watts
mega watt (MW) = 1,000 kW
giga watt (GW) = 1,000 MW

One watt-hour is equivalent to one watt of power consumed or generated continuously for one hour. The average New Zealand household consumes 8,000kWh or 8MWh of electricity annually. This is an equivalent amount of power used by 2kW electric kettle switched on for 160 days.

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Where can I find statistical and factual information?

There are several sites mentioned on our Links page.

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How much electricity can one marine turbine produce?

The amount of power each turbine will produce depends on the speed of the tidal flow, the size of the turbine rotor, the tidal cycle and the efficiency of the design. There are nearly two high tides and two low tides each 24 hours in the Kaipara. Each turbine will be in action for about 15 hours each day.

Spring tides generate more flow than neap tides, and the outgoing or ebb tide is more powerful than the incoming or flood tide. Wind, air pressure and rainfall in the catchment area also play a role in determining the speed of the tidal current. On average each turbine is expected to generate 0.75 MW. The formula is :

P = ½dAV3Cp

d = density of seawater (1.025 kg/m3)
A = swept area of the blades (m2)
V = velocity of the currents
Cp = power coefficient

Thus the current speed and blade radius are the major factors determining power output. Water is non-compressible and 830 times denser than air which also contributes to the high power output. Crest also knows that the ebb tide is not exactly the opposite of the flood tide. The Venturi shroud accelerates both flood and ebb currents. The output is enhanced further by currents entering the turbine off-centre through to an angle of 38°. In other words, the asymmetry of the currents is good news, even if this seems illogical.

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What happens when the tide is slack and not moving?

Marine turbines depend upon the current and slack tide means that generation will be minimal. The turbines will be arranged over a large distance and bathymetry surveys suggest that minor flows are always present. Nevertheless, for the 15 hours a day when there are tidal flows we can accurately predict the total output and sell that output effectively to complement other power sources. Currents range up to 2.5 metres per second (5 knots or 9 kph) and electricity generation should begin from about 0.7 metres per second of tidal flow.

Electricity systems manage major fluctuations in demand through the day and seasons. Any system must be capable of responding to these fluctuations. Relative to fluctuations in demand, those that occur due to changes in output of marine turbines are minor.

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Why do the turbines need so much space?

Further detailed work will determine the exact positioning of the turbines. They will be seven metres or more below the surface, silent and invisible. The turbines will be arranged in groups or arrays for technical reasons.

The turbines need to be apart from one another, and the groups well separated, to avoid interference and to maximise the yield from the current. Fluid dynamic studies suggest the groups need to be up to 500 metres apart, and we know that the main deep channel is narrow.

The direction of flood tidal current frequently is not always 180° from those of ebbing currents. The result is a requirement for about 8,000 metres of distance along the channel in order to position 200 turbines, and maintain the economic viability of the project.

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What is resource consent?

Resource consent allows a person or organisation to do something which may have an effect on the environment. For example, consent may be required before you discharge waste into the environment, divert a stream or build a bridge, clear vegetation or place a mooring, undertake earthworks or build a house. You will not be surprised that placing 200 marine turbines in the mouth of the Kaipara Harbour, burying 7 kilometres of cabling and erecting a substation requires consents from local, regional and government bodies. Crest Energy has submitted multiple applications pursuant to section 88 of the Resource Management Act 1991, which are being processed by Northland Regional Council.

For an understanding of the resource consents process visit the Northland site from our Links page. You may also review our applications and responses to official questions at our Consents page.

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How will the turbines be kept in place on the harbour floor?

The weight of the turbines and ballast will keep the turbines in place. There are several options for the exact engineering process but it is likely that quarried rock from the north east of the Kaipara Harbour will be brought in by barge to act as ballast.

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Can I buy 'green', renewable electricity for home?

In New Zealand electricity must be purchased from the electricity generators. Some generators are greener than others. See our Links page for the Greenpeace clean energy guide.

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Why use DC power (rather than AC)?

Large offshore wind farms over 100 MW generally use HVDC (High Voltage Direct Current) because DC technology :

emits about 5% of the electromagnetic radiation of AC which is good for elasmobranchs (sharks etc)
is economically viable for large MW power transfer over long distances to market
immune to types of faults associated with high voltage AC generation and transmission
allows power transfer oscillation between nil MW to 200 MW to nil MW over 6 hours
Gives capacitive re-charging of 100 km whereas HVAC cables would pose a significant limitation
matches voltage and current performance to periodic oscillatory nature of tides
not reliant on grid for synchronisation or reactive power-energy compensation
has a history to the 1870's for reliable operational service
Requires two submarine cables versus three larger cables for HVAC equivalent power ratings

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What sort of cable will be used?

Crest will use cables similar to those running under the Cook Straight, which were installed in the early 1960's to bring hydro power from the South Island to the North. The bipole HVDC cables are waterproof, salt corrosion resistant, solid plastic polymer, insulated copper with high mechanical strength. The cables are about 125 millimetres in diameter and buried over one metre under the harbour floor. Crest does not believe that buried DC cables will have any impact on marine navigation equipment.

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Why do you need a substation?

A substation will be sited at Northpower's existing Ruawai facility, opposite the school. The new building is similar to a large agricultural shed. It will be insulated for sound and trees and shrubs planted to minimise the visual impact. The building will house HVDC/HVAC converter equipment. The amount of converter equipment will grow as turbines are installed.

Cables will link the indoor converter to the outdoor substation within the existing fenced compound.There are several options to supply Crest electricity to customers including the use of lines to Dargaville and elsewhere that are already in place at Ruawai.

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What happens to the turbines if the project fails?

The turbine are removable can be taken away.

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Who are the main generators in New Zealand?

The five major generating companies – three State-Owned Enterprises (SOEs) and two private sector companies – listed by generating market share are:

Meridian Energy (SOE) 32% www.meridianenergy.co.nz
Contact Energy 24% www.contactenergy.co.nz
Genesis Energy (SOE) 18% www.genesisenergy.co.nz
Mighty River Power (SOE) 14% www.mightyriver.co.nz
TrustPower 5% www.trustpower.co.nz

Some generators are greener than others. See our Links page for the Greenpeace clean energy guide. Smaller generation exists, most of which is associated with industrial processes. Generation companies own and operate power stations. Most of New Zealand’s electricity is generated at remote locations and requires an efficient transmission system to transport it to the main demand centres. Around 40 sites supply electricity to the national grid. Some of the smaller scale generation is 'embedded' and feeds directly into local distribution networks.

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Are these turbines viable?

According to the investment bank Goldman Sachs 49 governments around the world provide incentives for sustainable energy projects. Wind power is now mature, and tidal turbines are well funded in Europe. The US government recently offered US$50 million in support of marine energy development. The UK government has spent perhaps GBP 50 million on marine energy. There are about a dozen companies offering marine turbine solutions. Some observers believe tidal power is at roughly the same stage of development as wind power was a decade ago. The NZ government has introduced a carbon emissions trading scheme, a Marine Energy Deployment Fund and released its Energy Strategy to 2050.

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How many people made submissions to date?

There were are remarkable number of people actively in support of the project on the first round of submissions which ended in January 2007, and a second round which ended in September 2007.

Often 90% or more of submissions are in oppostion to RMA applications. However in the case of this Project the supporters and opponents are about equal in number. Within the submissions of those opposed, many are concerned with a possible reduction in recreational and charter fishing. Crest Energy has tried to address the fishing worries by moving to deeper water away from mussel beds, eliminating the trans-harbour eastern cable route in favour of a shorter route to Pouto Point, and occupation of a smaller area in the harbour.

View	Number	Percentage
Support	123	49.6%
Oppose	121	48.8%
Other	4	1.6%
Total	248

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How do electricity prices in New Zealand compare internationally?

New Zealand has enjoyed some of the cheapest electricity prices in the world. As a result, conservation of energy, fuel efficiency and domestic insulation have been low priorities. Rising demand, declining output from the Maui gas field and changes in energy views have seen rapid price rises.

Nevertheless the price of electricity remains one of the lowest in the OECD. There is broad agreement that prices will continue to rise steadily because new, clean energy sources are in short supply. An Emissions Trading Scheme was announced by the government in September 2007 is likely to increase energy prices.

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How do tides work?

Tides are generated by the rotation of the earth within the gravitation fields of the moon and sun. Tides change each day in two main patterns:

A half-day cycle: due to the rotation of the earth within the gravitational field of the moon, resulting in a period of 12 hours 25 minutes between successive high tides
A 14-day cycle: resulting from alignment of the gravitational fields of the moon and sun. At new moon and full moon, the sun’s gravitational field reinforces that of the moon, resulting in the maximum difference between high and low tide, known as spring tides. At quarter phases of the moon, the sun’s attraction partially cancels that of the moon, resulting in minimum or neap tides. The range of a spring tide is typically about twice that of a neap tide.

The incoming, rising tide is the flood tide. The outgoing, falling tide is the ebb tide. The point halfway between high water and low water usually corresponds to the highest current velocity. The current is negligible at slack water.

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