What's the timetable?
How did this all start?
Can I see a map?
Where else in the world is tidal electricity an option?
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 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?
What's the timetable?
|
July 2005
|
- Company incorporated
|
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)
|
|
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 was oversubscribed. 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 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 indicates 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
Limited dated 23rd April 2010 was oversubscribed. This offer was not open to
the general public. Interested potential investors should visit our Investors
page.
|
Onwards
|
-
Crest to lodge further information with the Environment Court in August 2010
-
The Environment Court's decision and recommendation forwarded to the Minister of
Conservation
-
The Minister makes a decision for or against the project
- If ministerial decision is in favour of Crest’s applications, Crest raises pre-construction
capital via one or more possible mechanisms
-
The total funding requirement is over ten years is perhaps NZ$600 million
-
Capital will be raised in stages corresponding to project milestones
-
Full generation of up to 200 MW is planned for 2022
|
| | | | | | |
top
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).
top
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.
top
Where else in the world is tidal electricity an option?
top
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?
top
Will the project attract government
assistance?
Yes.
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$1.85 million from the New Zealand Marine Energy Deployment Fund (185 KB) by the
Energy Minister. The
NZ Energy Efficiency and Conservation Authority (EECA) administer the fund
on behalf of the Minister of Energy. The award is subject to the granting of resource
consents for the project. The NZMEDF runs for four years and offers a maximum of
NZ$ 8 million: the award to Crest is the maximum available in the first year.
top
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.
top
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)
top
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.
top
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.
top
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
|
| | | | | | | |
top
How do I register as a
supplier to Crest Energy?
Crest Energy is not yet ready to talk with potential suppliers.
top
Can I get a job at Crest Energy?
Not yet.
top
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.
top
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)!
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
Where can I find statistical
and factual information?
There are several sites mentioned on our
Links page.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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.
top
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
top
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.
top
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.
top
What happens to the turbines
if the project fails?
The turbine are removable can be taken away.
top
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 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.
top
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.
top
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
|
|
top
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.
top
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.
top
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.
top
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 kilometers,
the clearance above the turbines is increased from 5 to 7 meters, and the area covered
by the turbines redused from 1,300 to 300 hectares. 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.
top
|