How did this all
start?
The company was founded in July
2005. But the idea is not new: the Auckland Chamber of
Commerce unsuccessfully lobbied for tidal power in the
1920's (“Auckland’s Voice of Business: A history of the
Auckland Chamber of Commerce 1856-2006” chapter 3 page
51).
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Can I see a
map?
A quick way to get an
overview of the project is with our Slides. For photographs, maps and
diagrams, please see our Gallery.
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What are the risks in
this project?
The risks are similar to any major
project. Additional considerations for the Crest Kaipara
Energy Project are:
-
Political: will consents be granted by the authorities on viable terms?
-
Technical: will the combinations of turbines and cables work to specification?
-
Financial: will Crest Energy secure sufficient capital to execute the project?
-
Management: will Crest Energy attract the right people to complete the project?
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Will the project
attract government assistance?
Yes.
Prime Minister Helen Clark launched the New
Zealand Energy Strategy which includes a target to generate 90% of electricity from renewable resources by 2025, and to limit the construction of new fossil fuel generation plants for a decade. Current renewable output is about 60% of supply. There is limited scope for further large scale hydroelectric power generation. Geothermal and wind are well positioned and newer technologies such as wave and tidal were mentioned by the government: Crest Energy is named in the announcements. Meanwhile NZ Maui gas supplies used for electricity generation are running out and an alternative, the importation of LPG, would be even more expensive than renewables, according to Ministers.
A particular issue for northern NZ is that most electricity supply flows from south to north, and through the Auckland isthmus. The government has stated that it does not support a proposed gas plant north of Auckland near Helensville, close to Kaipara Harbour. Although there are many small initiatives to generate electricity north of Auckland, at this stage it would seem the Crest project may be valuable both for grid stability and security of supply to the north, once and if it comes on stream.
The Emissions Trading Scheme is good news for the Project. It may mean that the spot market electricity price line rises by about 10% over time. In addition Crest may provide VER's which are likely to trade at a discount to Kyoto carbon credits.
In May 2008 Crest Energy was awarded NZ$1.85 million from the
New Zealand Marine Energy Deployment Fund (185 KB) by the Energy Minister. The NZ
Energy Efficiency and Conservation Authority (EECA) administer the fund on behalf of the
Minister of Energy. The award is subject to the granting of resource consents for the project. The NZMEDF runs for four years and offers a maximum of NZ$ 8 million: the award to Crest is the maximum available in the first year.
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How will the project
be monitored?
Monitoring is an important
component of the Project. Monitoring data would be
evaluated by the Consent Authority under the auspices of
RMA s128 review before each stage of the project. A
draft monitoring plan is currently with the Department
of Conservation Whangarei office for comment and detailed discussions are in progress.
Baseline data would be
collected prior to the Stage 1 deployment, followed by a
period of monitoring during installation, with
monitoring covering a total of twelve months prior to
initiation of Stage 2. A similar process would be apply
for transition from Stage 2 to 3 and from Stage 3 to 4.
Monitoring before, during
and after installation of the various stages would allow
verification of the level of actual environmental
effect, would enable adverse effects to be determined
and would provide a basis for measures to avoid, remedy
or mitigate any such adverse effects as appropriate.
Monitoring will include a wide range of environmental
parameters and monitoring of the integrity of the
turbine structures themselves. Specific aspects to be
monitored will include:
-
Energy extraction through the tidal current devices
-
Interactions with tidal flow patterns, localised currents, sedimentation
processes and seabed bathymetry and morphology
-
Effects of support structures on the wave and tidal dynamics, possible
implications for local sedimentation and seabed movement, geotechnical and
geological aspects
-
Effects of the rotor interactions on the water column and the subsequent
effects on seabed morphology
-
Observed collision risk for marine life
-
Acoustic emissions and the potential implications involved with respect to
marine mammals and other marine ecology, such as fish
-
Vibration characteristics
-
Overall ecological impacts and benefits of installation and operation – direct
seabed disturbance, artificial reef effects
-
Recreational, commercial and non-commercial use of the harbour
Detailed monitoring
protocols will be defined in a monitoring plan to be
developed in consultation with stakeholders and the
Consent Authority.
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Why the Kaipara and
not other harbours?
The Kaipara Harbour has the biggest
tidal flows in New Zealand and is one of the largest
harbours in the world. During spring tides the current
in the Kaipara can exceed 9 kph (nearly five knots).
The
next four New Zealand harbours are Manukau, Hokianga,
Whangarei and Waitemata. The Kaipara has over double the
tidal flow of Manukau. Additional attractions of the
Kaipara are the lack of commercial shipping, proximity
to Auckland north of the isthmus, and relatively
low leisure usage of the harbour mouth.
The depth of the harbour mouth channel, where the turbines will be located, is an asset: neither too deep for access by divers if needed (31 mts to a maximum 52 mts), nor too shallow and therefore impacted by lack of water at low tide. The sandbar surrounding the mouth protects the project from oceanic waves.
| Harbour |
Water volume |
Average current |
|
Millions of cubic metres |
Metres/second |
Kilometres/hour |
Knots |
| Kaipara |
1,990 |
1.12 |
4.0 |
2.20 |
| Manukau |
918 |
0.92 |
3.3 |
1.80 |
| Hokianga |
228 |
0.81 |
2.9 |
1.60 |
| Whangarei |
164 |
0.54 |
1.9 |
1.00 |
| Raglan |
46 |
0.59 |
2.1 |
1.10 |
Hume and Herdendorf, 1992, 1993; and Hicks and Hume (1996)
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How big is the Crest
Kaipara Energy Project?
Crest's output would provide power
for the equivalent of 250,000 NZ homes. Crest aims to
generate about 3% of New Zealand's industrial,
commercial and residential electricity needs. Demand is
expected to rise 2% annually across the country and 5%
or more north of Auckland.
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How does tidal power
compare with other energy sources?
From an ecological and carbon
emissions viewpoint, tidal power looks healthy. Although
a study commissioned by Crest concerning the lifetime
carbon footprint including construction of tidal energy
as compared other sustainable energy sources in the NZ
environment is not yet complete, early indications are
that the footprint sequence is possibly hydro, tidal,
wind and finally geothermal.
Clearly all four of the
sustainable energy sources in the study have much lower
carbon footprints that conventional fossil fuel
generation plants.
Tidal seems to just come ahead of wind because the electricity output is more consistent,
and because wind turbines need to be very robust to withstand violent
gusts and sudden changes in wind direction.
Tidal energy short and long term
marginal costs seem economically similar to wind power.
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Will the project create jobs in
New Zealand?
General
averages suggest that large projects create jobs
locally, nationally and internationally in roughly equal
proportions. The Crest project could involve NZ$600
million of expenditure over the first ten years of the
project.
Figures from the
Industry Capability Network, part of NZ Trade and
Enterprise, suggest that eleven jobs are created by each
NZ$ million invested. Furthermore government expenditure
on unemployment benefit declines by NZ$118,000,
governnment income tax revenue increases by NZ$117,000
and there is an increase in purchasing power of
$195,000.
At present Crest's plans for
roles include:
| Monitoring
|
-
Several phases of detailed biological and environmental monitoring of the site
before, during and after construction
|
| Depot
|
-
Turbine fabrication and assembly, land-based maintenance, docking for marine
craft
|
| Materials
|
-
Steel, cables, composites, ballast, concrete, electrical equipment, marine
equipment, barges and boats
|
| Crews
|
-
Fabrication, assembly, installation, commissioning, maintenance and monitoring
of equipment offshore and on land
|
| Substation
|
-
Construction, commissioning, operation and maintenance; transformer, converter
and cooling equipment
|
| Cable
|
-
Trenching, installation, commissioning and maintenance
|
| Markers
|
-
Installation and maintenance of navigational markers
|
| Scoping
|
-
Professional services for the scoping of the project
|
| Core team
|
-
Provision of support for the day-to-day operation of the project
|
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How do I register as a supplier to Crest Energy?
Crest Energy is not yet ready to
talk with potential suppliers.
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Can I get a job at
Crest Energy?
Not yet.
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How do the currents go
in and out of the harbour?
Detailed current measurements using
GPS drogues show a number of different flows in the
Kaipara depending upon the tidal cycle (spring to neap).
The flow is asymetric meaning that the ebb and flood are
not identical in direction. The tidal current varies
between 1.6 and 2.5 metres per second (up to nine
kilometres per hour or five knots). The areas of
strongest current are on the western side of the harbour
mouth.
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Will the turbines get
covered in barnacles?
The tidal current varies between
1.6 and 2.5 metres per second (up to nine kilometres per
hour or five knots). The seawater carries sand particles
in suspension from harbours and rivers south of the
Kaipara, which is why there are huge sandhills and sand
extraction activities around the Kaipara. The sand will
help keep the turbines clean and reduce biofouling. Sand
falls out of the water flow and form deposits when the
current drops below 0.3 metres per second suggesting
that the turbines will not suffer from sand
sedimentation around them. The photo shows how much sand
there is (the dunes are about 120 metres or 400 feet
tall)!
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How will the turbines
be kept in position?
There is a firm footing for
turbines in the harbour mouth. Side sonar scans, CCTV
video footage, dredge samples and samples taken from the
harbour floor in the turbine area by commercial divers
suggest the floor is very hard and made up of either
bare scoured sandstone, or densely packed large grain
sand on a bed of sandstone. The divers used a water pump
and lance, sheer vane gauge and hand penetrometer to
asses the nature of the harbour floor. The divers also
noted that visibility is extremily poor in the channel.
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Will the turbines rust
rapidly in sea water?
All materials corrode to varying
degrees. A highly corrosive combination is air (oxygen)
and sea water. Our turbines are submerged with much less
oxygen than in air, which should give them a long life.
Crest estimates parts of the turbines will need
replacement each decade and that the turbines will be
subject to a regular maintenance and monitoring
programme.
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Will the turbines
damage dolphins?
Turbine rotors turn slowly to a
maximum of six revolutions a minute and are shielded.
The speed of the rotors depends upon the speed of the
current and the pitch of the turbine blades. A turbine
with a blade radius of nine metres has a space between
successive rotating blade tips of about 11 meters.
Marine mammals and fish sense and avoid obstacles
(Southern Right whale, NZ sea lion, orca and dolphin).
Dolphins are agile, communicative, have excellent eye
sight and echolocation. Crest believes the risks are
minimal for dolphins. The turbines will provide new
areas for fish and other life in the harbour mouth.
Sharks, rays and skates are also important and although
many people think they are slow and unresponsive, they
show remarkable agility and power to move fast when
necessary.
The Openhydro turbine is almost silent and should not, therefore, distract animals from their travels, particularly bearing in mind the high baseline noise from the sandbars surrounding the harbour mouth.
See the
NZ Department of Conservation guide to marine mammals for more information, and the
NZ Enclyclopedia which covers sharks, rays and skates.
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Will the project
damage birds?
Huge numbers of wading, migratory
and resident birds live in and around the harbour. The
cables are sited to avoid sensitive areas such as
seagrass (eelgrass) beds and tubeworms habitats. Away
from the main channel the cables will be in sand and
buried. The turbines may in fact increase the supply of
fish for birds by providing fish breeding sanctuaries in
the slower water at the base of the turbines. The panorama photo
below contains thousands of wading birds.
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Will the project harm
fishing?
There is a rumour
circulating that fishing from the shore, and fishing in
the harbour, will be banned: this is not true.
Consultations indicates that
a key fishing area is around the mussel beds in known as
the Graveyard, presumably named because of the many
shipwrecks in the area. Crest Energy side-scan sonar
surveys identified the location of the mussel beds and
nature of seabed in the turbine array area. The turbines
will be located to greater than 31 metres depth which provides
separation from mussel beds, and avoids primary areas of
fishing use.
Longer term Crest Energy do not
think the project will reduce the enjoyment of anglers.
Consultations suggest that the area of the turbines is
seldom used for fishing, even at slack water due to the
depth of the channel of up to 50 metres. During ebb and
flood water the turbine area is dangerous and anchoring
difficult for leisure craft. The fishing that does take
place near the turbine area is sited closer to the
shore, or further out to sea.
A significant point to note
is the differences between the old and new RMA
applications made in response to concerns expressed in
public submissions to the project up until 12th January
2007. The original outlined a cable running east-west
across the harbour for over 30 kms, whereas the new
route is about 7 kms from the array area to Pouto Point.
This enormously reduces the footprint of the Project and
the level of impact on fishing activities.
There is siginficant
evidence from similar structures used in offshore oil
and gas fields to suggest that fish stocks and
bio-diversity will be improved by the presence artificial sanctuaries. In other words, over several years Crest
believes the turbines will make a significant and positive
contribution to the health of the Kaipara harbour.
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Will the cables cause
problems anchoring, or to animals?
The Kaipara is over 900 square
kilometres and Crest Energy has applied to occupy a tiny
fraction of the area. A pair of cables will run seven
kilometres from the harbour mouth to Pouto Point on
North head. They will be buried over one metre below the
harbour floor, usually in sand. Leisure
craft will be able to anchor over the cable but will be
probably be restricted from anchoring in the turbine area. The
cables are both buried and shielded. Similar cables are
used all over the world.
The cables will carry DC
electricity which is important since the electromagnetic
interference is 5% of the impact for AC. Sharks, rays
and skates are particularly sensitive to high
electromagnetic levels. The burial process itself will
cause short term disruption to harbour floor animals and
plants. The cables are about 125 millimetres in
diameter.
A second type much smaller cabling will link the turbines together and join with the main submarine cable at one or more hubs. Each array or loop will manage between 10 and 30 turbines.
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What happens if the
main channel changes?
Early European maritime charts date
from the middle of the 19th century. The main channel
through the harbour mouth, where Crest plans to place
turbines, does not appear to have moved in 150 years.
Although the sandbars clearly shift, their overall
position has not changed.
The cables include a fibre optic
strand. Changes in pressure and tension can be measured
accurately and Crest will be alerted quickly to
movements on the harbour floor, and issues with the
cables. In this event Crest can either move the cables
and bury them elsewhere, or cover them with harmless
ballast, or use a kind of blanket to shield the eroded
area. The marine chart below shows the main channels.
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What happens if the
cables break?
The cables are buried over one
metre below the harbour floor in sand. If the cables are
broken, as has happened for a variety of reasons with
other marine cables, repair should take 48 hours.
Locating the break is done using feedback from the fibre
optic strand in the cable which measures changes in
tension and pressure. Weather conditions inside the
Kaipara do not present additional hazards such as ice
and large waves.
The most common insurance claim by offshore wind farms in Europe is for cable damage caused usually by commercial vessels. The Kaipara harbour has very limited commercial vessel activity confined to sand mining barges on the eastern edge of the harbour.
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Will the turbines
prevent access to leisure craft?
The turbines will be positioned seven
metres below low water (about 24 feet), meaning that
leisure craft can pass freely over the turbines at all
times. The harbour mouth is nearly six kilometres wide
and the turbines will occupy a small percentage of the
width.
The turbines will be limited to the 31 metre
contour of the deep water channel, and below. Commercial
traffic, apart from sand barges, is minimal due to the
dangerous sandbars at the harbour mouth and the low
population of the catchment area. The sandbars outside
the harbour mouth offers about five metres draught at
low tide: few large craft are likely to attempt to
enter the harbour.
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If the turbines are
seven metres underwater, can a storm destroy them?
The prevailing weather on the
Tasman is from the south west and very large storms are
common. However the turbines are protected by the
sandbars that surround the harbour mouth. The sandbars
limit navigation to vessels with well under five metres
draught. Many parts of the sandbars are exposed at low
tide.
There are over 100 documented shipwrecks around the
sandbars. The area in which Crest will install turbines
is calmer with the largest waves at about 1.50 metres.
The first photograph below is unusual since the waves
were created by the current (standing waves), and not by
the action of wind or waves from out to sea.
Conditions in the harbour mouth can be very dangerous for smaller craft in particular when high winds blow in the opposite direction to the tidal flow, causing choppy seas that can flood a small boat.
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Where are the
shipwrecks?
The Kaipara, like many harbours
around New Zealand, is hazardous for shipping. According
to Maritime New Zealand there are three types of harbour
bar - dangerous, very dangerous and lethal - the Kaipara
Harbour is no exception.
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What is the difference
between megawatts (MW) and megawatt-hours (MWh)?
A watt is the unit rate at which
work is done in an electrical circuit. A light bulb
typically has a power requirement of 100 Watts.
kilo watt (kW) = 1,000 watts
mega watt (MW) = 1,000 kW
giga watt (GW) = 1,000 MW
One watt-hour is equivalent to one watt of power consumed or generated
continuously for one hour. The average New Zealand household consumes
8,000kWh or 8MWh of electricity annually. This is an equivalent amount of power
used by 2kW electric kettle switched on for 160 days.
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Further detailed work will
determine the exact positioning of the turbines. They
will be seven metres or more below the surface, silent and
invisible. The turbines will be arranged in groups or arrays for
technical reasons.
The turbines need to be apart from
one another, and the groups well separated, to avoid
interference and to maximise the yield from the current.
Fluid dynamic studies suggest the groups need to be
up to 500 metres apart, and we know that the main deep
channel is narrow.
The direction of flood tidal
current frequently is not always 180° from those of
ebbing currents. The result is a requirement for about
8,000 metres of distance along the channel in order to
position 200 turbines, and maintain the economic
viability of the project.
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What is resource consent?
Resource consent allows a person or organisation to do something which
may have an effect on the environment. For example, consent may be required
before you discharge waste into the environment, divert a stream or build a
bridge, clear vegetation or place a mooring, undertake earthworks or build a
house. You will not be surprised that placing 200 marine turbines in the mouth
of the Kaipara Harbour, burying 7 kilometres of cabling and erecting a
substation requires consents from local, regional and government bodies. Crest
Energy has submitted multiple applications pursuant to section 88 of the
Resource Management Act 1991, which are being processed by Northland Regional
Council.
For an understanding of the resource consents process visit the Northland site
from our Links page. You may also
review our applications and responses to official questions at our
Consents page.
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How will the turbines be kept
in place on the harbour floor?
The weight of the
turbines and ballast will keep the turbines in place.
There are several options for the exact engineering
process but it is likely that quarried rock from the
north east of the Kaipara Harbour will be brought in by
barge to act as ballast.
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Can I buy 'green', renewable
electricity for home?
In New Zealand electricity must be purchased from the electricity
generators. Some generators are greener than others. See our
Links
page for the Greenpeace clean energy guide.
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Why use DC power (rather than AC)?
Large offshore wind farms over 100 MW generally use HVDC (High Voltage
Direct Current) because DC technology :
-
emits about 5% of the electromagnetic radiation of AC which is good for
elasmobranchs (sharks etc)
-
is economically viable for large MW power transfer over long distances to
market
-
immune to types of faults associated with high voltage AC generation and
transmission
-
allows power transfer oscillation between nil MW to 200 MW to nil MW over 6
hours
-
Gives capacitive re-charging of 100 km whereas HVAC cables would pose a
significant limitation
-
matches voltage and current performance to periodic oscillatory nature of tides
-
not reliant on grid for synchronisation or reactive power-energy compensation
-
has a history to the 1870's for reliable operational service
-
Requires two submarine cables versus three larger cables for HVAC equivalent
power ratings
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What sort of cable will be used?
Crest will use
cables similar to those running under the Cook Straight,
which were installed in the early 1960's to bring hydro
power from the South Island to the North. The bipole
HVDC cables are waterproof, salt corrosion resistant,
solid plastic polymer, insulated copper with high
mechanical strength. The cables are about 125
millimetres in diameter and buried over one metre under
the harbour floor. Crest does not believe that buried DC
cables will have any impact on marine navigation
equipment.
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Why do you need a substation?
A substation will
be sited at Northpower's existing Ruawai facility,
opposite the school. The new building is similar to a
large agricultural shed. It will be insulated for sound
and trees and shrubs planted to minimise the visual
impact. The building will house HVDC/HVAC converter
equipment. The amount of converter equipment will grow
as turbines are installed.
Cables will link the indoor
converter to the outdoor substation within the existing
fenced compound.There are several options to supply
Crest electricity to customers including the use of
lines to Dargaville and elsewhere that are already in place at
Ruawai.
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What happens to the turbines if the
project fails?
The turbine are
removable can be taken away.
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Who are the main generators in
New Zealand?
The 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.
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Are these turbines viable?
According to the
investment bank Goldman Sachs 49 governments around the
world provide incentives for sustainable energy projects. Wind power is now mature, and tidal turbines are
well funded in Europe. The US government recently
offered US$50 million in support of marine energy
development. The UK government has spent perhaps GBP
50 million on marine energy. There are about a dozen
companies offering marine turbine solutions. Some
observers believe tidal power is at roughly the same
stage of development as wind power was a decade ago. The
NZ government has introduced a carbon emissions trading
scheme, a Marine Energy Deployment Fund and released its Energy Strategy to 2050.
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How many people made
submissions to date?
There were are
remarkable number of people actively in support of the
project on the first round of submissions which ended in
January 2007, and a second round which ended in September 2007.
Often 90% or more of submissions are in oppostion to RMA applications. However
in the case of this Project the supporters and opponents are about equal in
number. Within the submissions of those opposed, many are concerned with a
possible reduction in recreational and charter fishing. Crest Energy has tried
to address the fishing worries by moving to deeper water away from mussel beds,
eliminating the trans-harbour eastern cable route in favour of a shorter route
to Pouto Point, and occupation of a smaller area in the harbour.
|
View
|
Number
| Percentage |
|
Support
|
123
| 49.6% |
|
Oppose
|
121
| 48.8% |
|
Other
|
4
| 1.6% |
|
Total
|
248
| |
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How do electricity prices in
New Zealand compare internationally?
New Zealand has
enjoyed some of the cheapest electricity prices in the
world. As a result, conservation of energy, fuel
efficiency and domestic insulation have been low
priorities. Rising demand, declining output from the
Maui gas field and changes in energy views have seen
rapid price rises.
Nevertheless the price of electricity
remains one of the lowest in the OECD. There is broad
agreement that prices will continue to rise steadily
because new, clean energy sources are in short supply.
An Emissions Trading Scheme was announced by
the government in September 2007 is likely to
increase energy prices.
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.
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:
