David Tucker, of Dunedin, is backing tidal power generation
on Otago Harbour, possibly including a barrage crossing the
harbour's bottleneck from Port Chalmers to Portobello and
linking Goat and Quarantine islands (pictured behind).
Photo by Gregor Richardson.
There are renewed calls for Dunedin to consider investing
in tidal power generation in Otago Harbour, stimulated by
progress towards a $600 million scheme north of Auckland.
Auckland-based power company Crest Energy is seeking consent
for a 200-turbine, 200-megawatt scheme, costing about $600
million, at the entrance to Kaipara Harbour.
The scheme would be the first of its kind in New Zealand, and
could power 250,000 homes.
The Environment Court has given a positive recommendation to
Conservation Minister Tim Groser, while requesting work to
address lingering environmental concerns.
The progress encourages David Tucker, of Dunedin, who argues
a similar scheme should be considered for Otago Harbour.
Mr Tucker, a semi-retired consultative engineer and former
Dunedin City Council consultant, said Otago Harbour could be
as effective as a source of renewable energy.
He envisaged turbines on the sea floor at the mouth of Otago
Harbour, driven by the tide to generate power, or a barrage
from Port Chalmers to Portobello - or both.
The barrage would take advantage of a natural bottleneck
between Port Chalmers and Portobello, linking Goat and
Quarantine Islands, trapping water in the upper harbour
during high tide and releasing it at low tide.
Water flowing in both directions could drive turbines inside
the barrage, but the barrier could also provide protection
from sea level rise, he said.
He planned to discuss his ideas with Aurora Energy Ltd, a
Dunedin City Council-owned company, and believed feasibility
studies should be considered.
Sustainable Dunedin co-chair Dr Jocelyn Harris agreed, saying
she supported investment in tidal power schemes and other
forms of renewable energy.
"We have to start thinking about things as creatively and
widely as possible, and we have to start thinking about it
fast."
Aurora chief executive Grady Cameron, of Dunedin, said tidal
and wave power generation technology was in its infancy, but
developments were being closely watched by his company.
It was possible a development could feature on Otago Harbour
as technology improved and costs made schemes more economic.
"It [tidal] is probably 10 to 15 years behind where we are
with wind power.
It's very much in its infancy.
"At this stage, I don't think there's one technology that's
really proven itself," he said.
TrustPower community relations manager Graeme Purches agreed,
saying tidal technology was still "experimental", with
technical challenges still to be resolved and few examples of
operational schemes globally.
"The cost of the output of that generation at this point in
time is not viable. There's too many better alternatives, in
our view."
Crest Energy director Anthony Hopkins, of Auckland, said
there were no plans to expand the company's operations to
include other New Zealand harbours, although he agreed
improved technology could make smaller projects more
feasible.
The company had considered 57 harbours around New Zealand
before drawing up a shortlist of five.
Otago Harbour did not feature on that shortlist, he said.
Kaipara Harbour was the country's largest harbour, he said,
while the second largest, Manukau Harbour, was about half the
size of Kaipara Harbour.
It was hoped approval for the Kaipara project would come this
year, but construction was unlikely to begin for a further
two years.
chris.morris@odt.co.nz
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