Who owns Crest
Energy?
Has Crest consulted with the local
community?
Is tidal energy much more expensive than existing
NZ hydro electricity?
If the project fails, who will return the harbour to
its current state?
How is the environment being looked after?
Will the project benefit the local economy?
Where tidal technologies are deployed today?
Will snapper stocks be damaged?
How big are the turbines?
What's the history?
How did this all start?
Can I see a map?
Where else in the world is tidal electricity an option?
What are the commercial risks in this project?
Does the project attract government support?
Why the Kaipara and not other harbours?
How will the project be monitored?
How does tidal energy's carbon footprint compare
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?
What is the difference between megawatts and megawatt-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 about a tunnel between Manukau Harbour and the
Hauraki Gulf to power turbines based upon the tidal differences between the two
bodies of water?
How do electricity prices in New Zealand compare
internationally?
How do tides work?
What are the differences between the 2006 and 2007
RMA applications?
Who owns Crest Energy?
Over 99% of the shares are owned by New Zealanders.
Has Crest consulted with the local community?
Crest undertook a major consultation programme with key stakeholders. Judge Newhook
of the Environment Court noted in his December 2009 Interim Decision that '... attempts
by Crest to consult were extensive, considerable and meaningful ...'.
Crest held well over 100 consultative meetings over five years with interested parties.
The consultations included those with the Auckland Regional Council, Northern Regional
Council, Rodney District Council and Kaipara District Council.
Representatives of Environs Holdings on behalf of Te Uri o Hau provided Crest with
a Cultural Impact Assessmentdocument outlining their understandings of the
project and its potential impact on their community and the harbour.
Crest also attended hui and met with many other interest groups and individuals.
Many companies have expressed interest in the commercial and economic opportunities
which may be created in and near the Kaipara by the project, and have also met with
Crest.
As a result of the consultation processes Crest withdrew its July 2006 consent applications
and made revised applications in July 2007 which incorporated modifications arising
from community and stakeholder feedback.
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Is tidal energy much more expensive than existing
NZ hydro electricity?
It is not possible to directly compare the pricing of tidal and hydro generated
electricity as there are many different considerations to take into account e.g.
a major percentage of the hydro generation system is from legacy state-funded developments,
some of which are more than 50 years old - if these had to be built today it would
be at very significant cost in real terms, with consequent implications for power
pricing.
The price comparison of tidal power is not against legacy hydro schemes but against
new fossil fuel based power stations where typically the new gas supply is very
much more expensive than many people imagine, as is the electricity generated by
such new stations.
Another consideration is that we have reached maximum capacity of available resources,
and the pricing of new generation capabilities to meet the rising demand for electricity
in New Zealand. For a secure and sustainable future we have to develop renewable
resources. We simply cannot afford not to.
What we can say about the cost of tidal power is that it provides predictability
of supply, enabling smoothing, optimisation and management of resources. This means
that it will be less subject to the external price fluctuations we see with other
sources of power. If anything tidal turbines will depress the spot electricity price,
not inflate it.
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If the project fails, who will return the harbour
to its current state?
Both the original 2008 Northland Regional Council recommendations and those of the
2011 Environment Court decision contain conditions for a large financial bond.
The purpose of the bond is to provide for the removal by independent contractors
of materials related to the project from the harbour, should the project be abandoned
after construction begins. The bond is automatically adjusted for inflation and
there are specific conditions in place for the periodic review of the size and purpose
of the bond.
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How is the environment being looked after?
This project has evolved through five years continuous research and investigative
processes, in which a key focus has been to identify any potential effects on the
harbour environment.
The rigorous Environment Court process ensured extensive analysis, debate and input
from independent experts, Tangata Whenua and interested parties. The consent conditions
provide for extensive monitoring and assessment throughout staged development of
the project.
The Environment Court's project conditions, and in particular the Environmental
Monitoring Plan, has 103 pages of detailed monitoring requirements and identifies
responsibilities and processes for the initial and continuous obligations imposed
under the consent.
The EMP was developed jointly over several years in consultation with stakeholders,
the Northern Regional Council, the Department of Conservation, interested parties
and experts giving evidence to the Environment Court.
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Will the project benefit the local economy?
We intend to incorporate as much NZ content as feasible and Crest intends to source
and manufacture locally when possible.
The development of competitive local supply chains into a major project will have
substantial economic benefits.
Crest volunteered to fund a significant “Crest Energy Kaipara Trust” for the benefit
of the health of the harbour. Community trustees will be needed once the project
is in operation to manage the trust on behalf of all users of the Kaipara.
A 2006 study carried out by Business and Economic Research Ltd (BERL) for the Industry
Capability Network (a unit of NZ Trade and Enterprise), established that every $1
million spent in manufacturing activity in New Zealand generates an extra 11 jobs,
NZ$117,000 tax revenue, $195,000 of purchasing power and $119,000 saving of government
welfare payments.
We estimates total potential expenditure of around NZ$600 million during the first
ten years of the project. Many of the skills needed for the project are common to
ship building and large construction projects. This is potentially a substantial
capital injection into Northland Region’s population of 160,000 people.
A generally agreed average for large projects is that expenditure is equally split
across the region, nation and internationally. If these averages hold true for the
Kaipara project over the first ten years of the project, about $200 million will
be spent in Northland and Auckland, a further $200 million nationally and the balance
overseas.
Some components of the project are not available and are unlikely to be available
in NZ such as submarine electrical cabling, complex electrical control equipment
and turbine technologies.
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Where tidal technologies are deployed today?
There are deployments of marine tidal turbines including those in Norway, Northern
Ireland, USA, Canada, Australia, South Korea and Scotland. Large international technology
companies are investing their capital and engineering expertise in tidal technologies.
We recognise that there are concerns about the implementation of new technologies:
however there is widespread international recognition of the significance of the
ocean energy sector, which is supported by high levels of investment and commitment
to the development of this energy source in many countries.
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Will snapper stocks be damaged?
A NIWA scientist and expert witness
for the NRC during the Environment Court hearing indicated that his opinion was
that there is a low risk that the project would adversely affect snapper and fisheries.
His evidence was given in the context of other research showing the importance of
the Kaipara harbour to the north-western New Zealand fishery.
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How big are the turbines?
Bearing in mind that consents are for a period of 35 years, the company applied
for the maximum possible size of turbine that could fit in the harbour mouth.
This does not mean that large turbines will be installed immediately: it means Crest
is taking heed from some other projects (particularly wind) where permits were gained
for small turbines which subsequent technological developments made redundant.
Most turbines being built today are ten metres in diameter, although some of the
latest designs are as large as 17 metres. Potentially Crest’s could be as large
of 25 metres, sited invisibly seven metres below the surface of the water in water
31-52 metres deep.
Crest has not yet made a decision on the initial supplier or suppliers of turbines
for the project.
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What's the history?
July 2005
|
- Company incorporated, consultation with the local communities and project investigations
begin
|
July 2006
|
- First applications for permits
|
December 2006
|
- Public submissions for and against the Kaipara project for 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, and Crest
provides further information requested by Council officers (these are called S92s;
other s92’s were answered in November 2006)
|
June 2007
|
- As part of Crest's extensive consultations with Tangata Whenua, representatives
of Environs Holdings on behalf of Te Uri o Hau provided Crest with an extensive
and carefully prepared Cultural Impact Assessmentdocument outlining their
understandings of the project and its potential impact on their community and the
harbour
|
July 2007
|
- Crest applies for adjusted consents in response to public submissions received in
January 2007.
- The revised applications require less marine cabling (33 to 7 kilometres), occupy
less space in the harbour (1,300 to 350 hectares) and place turbines deeper below
the surface of the sea (7 to 5 metres).
- The new applications also mean that previous applications with Rodney District Council
and the Auckland Regional Council are no longer required.
- Kaipara District Council pursuant to Section 139 of the RMA certify that the overland
reticulation of power generated by the project is a permitted activity as defined
in the District Plan
|
September 2007
|
- Second round of public submissions to the applications closed (about 123 in favour,
121 against)
|
October 2007
|
- Northland Regional Council begin writing the Staff Report, a detailed consideration
of the Project
- Three independent Commissioners form a panel to consider the evidence for and against
the applications
|
November 2007
|
- The Invitation to eligible investors to apply for shares in Crest Energy Limited
dated September 2007. This offer was not open to the general public. Interested
potential investors should visit our Investors
page.
|
May 2008
|
- Marine Energy Deployment Fund first NZ$1.85 million grant awarded to Crest by the
Minister of Energy, subject to the granting of consents for the project.
- Five days of regional authority Hearings
|
August 2008
|
- The Northland Regional Council recommends that the Minister of Conservation approve
a staged tidal power plant in the Kaipara Harbour.
|
September 2008
|
- Two parties launched appeals to the Environment Court requesting the project be
declined in its entity. Two further appeals centre around consent conditions rather
than objections to the entire project.
|
June 2009
|
- Appeal by Environs Holdings to the Auckland High Court to delay Environment Court
Hearings denied.
- The Environment Court convened in Whangarei under Judge Newhook to consider Crest's
applications for resource consents. Over 30 expert witnesses offered evidence.
|
July 2009
|
- Leading New Zealand energy producer and retailer
Todd Energy takes cornerstone stake in Crest Energy. Todd Energy owns and operates
its own natural gas, oil, LPG, electricity, cogeneration and solar hot water heating
assets, enabling it to manage the flow of energy from exploration and production
for its industrial, commercial and residential customers. Todd Energy has significant
investments in renewable generation developments including hydro, geothermal and
landfill gas energy plants. Todd Energy is also the largest generator of electricity
in New Zealand from efficient gas-fired co-generation facilities.
|
December 2009
|
- The Environment Court’s interim decision indicated a possible positive recommendation
for the project subject to some additional fact finding and the preparation of a
draft environmental monitoring plan.
|
May 2010
|
- A second Invitation to eligible investors to apply for shares in Crest Energy
Limiteddated 23rd April 2010. This offer was not open to the general public.
Interested potential investors should visit our
Investors page.
|
August 2010
|
- Crest filed further documents with Environment Court participants following extensive
additional consultation with experts on mainly two subjects: the detailed Environmental
Monitoring Plan for the project, and the impact (if any) of the Project on snapper.
|
February 2011
|
- The Environment Court recommended that the Honourable Kate Wilkinson, Minister of
Conservation, approves Crest's applications for the development of a tidal power
station
|
March 2011
|
- New Zealand's Minister of Conservation approves Crest's applications
|
August 2011
|
|
Onwards
|
- Crest raises pre-construction capital
- The total funding requirement is over ten years is perhaps NZ$600 million
- Capital will be raised in stages corresponding to project milestones
- Generation of up to 200 MW is planned for 2023
|
top
How did this all start?
The company was founded in July 2005. The idea is not new: the Auckland Chamber
of Commerce lobbied unsuccessfully for tidal power in the 1920's. Please see Auckland’s
Voice of Business: A history of the Auckland Chamber of Commerce 1856-2006 chapter
3 page 51.
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Can I see a map?
For photographs, maps and diagrams, please see our
Gallery .
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Where else in the world is tidal electricity
an option?
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What are the commercial risks in this project?
The risks are similar to any large infrastructure project. Additional considerations
for the Crest Kaipara Energy Project are:
- Financial: will Crest Energy secure sufficient capital to execute the project?
- Management: will Crest Energy attract the right people to complete the project?
- Forecasting: future cost of funds and future wholesale electricity price path
- Environmental: the adaptive management regime and the environmental conditions under
which the project's consents are granted prove too arduous
- Technical: will the combinations of turbines and cables work to specification?
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Does the project attract government assistance?
Ex-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 a rigorous
set of milestones. 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 and the funds can
only be used for turbine construction and installation.
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How will the project be monitored?
Monitoring is an important component of the Project. Monitoring data will be evaluated
by the consent authority (Northland Regional Council) under Section 128 of the Resource
Management Act, before the start of each stage of the project. Monitoring will also
occur continuously during operation of the power station.
Two years of baseline data will be collected prior to the Stage 1 deployment, with
monitoring continuing during Stage 1 and for a minimum of 12 months after completion
of Stage 1 prior to initiation of Stage 2. A similar process will apply for the
transition between later stages. The stages are for 3,20, 40, 80 and 200 turbines.
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
- Recreational, commercial and non-commercial use of the harbour
Detailed monitoring protocols are contained within the 103 pages of consent conditions
agreed by the Environment Court within the Environmental Monitoring Plan.
The EMP was developed jointly in consultation with stakeholders, the Northern Regional
Council, the Department of Conservation and experts giving evidence to the Environment
Court.
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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 metres to a maximum 52
metres), 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's carbon footprint compare
with other energy sources?
In 2007 CREST provided some funding assistance two University of Auckland environmental
engineering students to research the full life carbon cycle of four NZ sustainable
energy sources: tidal, wind, hydro and geothermal. Their findings are summarised
below:
Full life carbon
|
Embodied energy Kilo joules per kilowatt hour
|
Carbon dioxide emissions Grams of CO2 per kilowatt
|
Tidal
|
42
|
1.8
|
Wind
|
70
|
3.0
|
Hydro
|
55
|
4.6
|
Geothermal
|
105
|
6.3
|
Combined cycle gas
|
N/A
|
200-300
|
Coal
|
N/A
|
400-1,000
|
The study found that tidal is amongst the cleanest (in CO2 terms) of renewable electricity
sources. Wind is less predictable and consistent, increasing the footprint. Hydro
uses huge amounts of energy for the steel and concrete in the dams and waterways,
and for the energy used initially for vegetation clearance and roads. Geothermal
uses high quality of materials with high energy contents to operate in hostile geothermal
environments and the materials require frequent replacement.
Coal and gas produce hundreds of times more emissions than renewable sources.
NZ national average emissions are about 210 grams CO2 equivalent per KWh which is
internationally low due to the high contribution of hydro to NZ electricity production.
Figures for Huntly coal are 958 g CO2/KWh and Otahuhu B gas 372 g CO2/KWh, according
to Energy Modeling Consultants Ltd November 2008 report.
Tidal energy short and long term marginal costs seem economically similar to those
of wind power, and those of tidal energy can only improve as more turbines are deployed
around the world.
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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, government income tax
revenue increases by NZ$117,000 and there is an increase in purchasing power of
$195,000.
Crest Energy does not currently have agreements in place concerning recruitment
and the supply of products and services.
Consideration of potential suppliers may commence in late 2011.
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.
Crest Energy does not currently have agreements in place concerning recruitment
and the supply of products and services.
Consideration of potential suppliers may commence in late 2011.
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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 the flows in the Kaipara depending
upon the tidal cycle (spring to neap). The flow is slightly asymmetric meaning that
the ebb and flood are not exactly opposite in flow directions. 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 end 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 sand hills
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. Sonar sidescans, 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 deeper bed of sandstone.
The divers used a water pump and lance, sheer vane gauge and hand penetrometer to
assess the nature of the harbour floor. The divers also noted that visibility is
extremely poor, or zero, in the main channel.
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Will the turbines rust rapidly in sea water?
All materials corrode to varying degrees. A highly corrosive combination is the
oxygen in air, and sea water. Turbines are submerged with much less oxygen than
in air, which should give them a long life. Parts of the turbines will need replacement
each decade. The turbines will be subject to regular maintenance.
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Will the turbines damage dolphins?
Turbine rotors turn slowly at about 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.
Turbines are 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 Encyclopedia 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 indicate 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's
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 mostly avoids the primary
areas of fishing use since the mussel beds are in shallower water.
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 52 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 near the escarpment that runs east-west along the main channel,
or further out to sea.
A 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 kilometres, whereas the new route is about 7 kilometres from the array
area to Pouto Point. This enormously reduces the footprint of the Project and the
level of impact on fishing activities.
There are indications from 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 maintaining the biodiversity and richness of the Kaipara
harbour.
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Will the cables cause problems anchoring, or to
animals?
The Kaipara is over 738 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. The cables will be buried one metre
below the harbour floor. The harbour floor along the route is usually sand, according
to Crest's initial survey. Leisure craft will be able to anchor over the cable but
will be restricted from anchoring or passing over 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 23 feet), meaning
that leisure craft can pass over the turbines but for safety reasons access to the
turbine area will be restricted. The harbour mouth is nearly six kilometres wide
and the turbines will occupy a small part of the width.
The turbines will be limited to the 31 metre contour and below of the deep water
channel. 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:
therefore few large craft 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 storms are common.
However the turbines are protected from the full impact of oceanic conditions by
the sandbars that surround the harbour mouth. The sandbars limit navigation to vessels
with under five metres draught. 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. An incandescent
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 six months. Houses in the north generally consume less electricity that those
in the south, due to the warmer climate. Over half of domestic electricity consumption
is for hot water heating.
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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 14 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. Crest Energy submitted
multiple applications pursuant to section 88 of the Resource Management Act 1991
in 2006/7, which were processed by Northland Regional Council. Permits eventually
granted by the Minister of Conservation in March 2011.
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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.
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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 volume of converter equipment will
grow as turbines are installed.
Cables will link the indoor converter to the outdoor substation within the existing
fenced compound.
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What happens to the turbines if the project
fails?
Both the original 2008 Northland Regional Council recommendations and those of the
Environment Court contain conditions for a large financial bond.
The purpose of the bond is to provide for the removal by independent contractors
of materials related to the project from the harbour, should the project be abandoned
after construction begins. The bond is automatically adjusted for inflation and
there are specific conditions in place for the periodic review of the size and purpose
of the bond.
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Who are the main generators in New Zealand?
The major generating companies (three State-Owned Enterprises (SOEs) and three private
sector companies) are:
Some generators are greenerthan others.
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?
There were are remarkable number of people actively in support of the project on
the two rounds of public submissions of January 2007 and September 2007.
Often 90% or more of submissions are in opposition 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
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Number
|
Percentage
|
Support
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123
|
49.6%
|
Oppose
|
121
|
48.8%
|
Other
|
4
|
1.6%
|
Total
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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 about a tunnel between Manukau Harbour and
the Hauraki Gulf to power turbines based upon the tidal differences between the
two bodies of water?
Many people have suggested a tunnel between the Manukau Harbour and Hauraki Gulf
to power turbines based upon the tidal differences between the two bodies of water.
The concept is common in freshwater hydro schemes where tunnels are often used to
give a strong and directed head of water, sometimes over long distances.
Marine currents generally flow from west to east in the southern hemisphere, which
means, for example, that some Pacific species are common on both sides of the tip
of South America, but Atlantic species are far less common on the Pacific side.
Current generally flow across the Tasman around NZ, meaning that Tasman species
are found in the Gulf, but the reverse is less common. In the NZ context there are
additional concerns from Maori around mixing water catchments. Given that there
has been portage between the two harbours and ships have discharged foreign species
from their ballast for generations, there is an argument to say that whatever damage
that might be caused by water flow has already occurred and is irreversible.
Nevertheless, the effort to gain consents would be huge and similar initiatives
such as hydro between lakes in the deep south of NZ have yet --- or may never ---
be developed.
The benefits of linking the Manukau Harbour and Hauraki Gulf may be limited. We
can calculate the potential power output based on the water level difference between
the two harbours (maximum four metres which is very small in hydro terms), and estimate
the costs of a large diameter tunnel between the two harbours: the project is unlikely
to be economically viable.
Soft mud and shale are difficult to tunnel, so another factor is the geology of
the route. Assuming the intakes/outtakes would need to be several kilometres from
the shore, there would be considerable flexibility about the tunnel route rather
than being limited to the traditional portage routes across the Auckland isthmus.
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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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What are the differences between the July 2006
and July 2007 RMA applications?
In summary, the main sea floor cabling is reduced from 33 to 7 kilometres, the clearance
above the turbines is increased from 5 to 7 meters, and the area covered by the
turbines reduced from 1,300 to 300 hectares. Old applications relating to the east-west
30 kilometres cable route terminating at the Hoteo River, and the proposed substation
in Rodney, were withdrawn and replaced 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.
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