How do you upgrade a 43-year-old powerhouse? David
Bruce went to the Benmore power station to find out.
The Benmore powerhouse is undergoing a $67 million
refurbishment and upgrade by Meridian Energy Ltd which will
improve its efficiency and produce more electricity. Photo
by David Bruce.
Cheek plates, wicket gates, thrust guard bearings and head
covers - it's a whole new language for the layman when it
comes to spending $67 million to refurbish and upgrade the
Benmore power station.
Compare that $67 million to the $62 million total cost of the
Benmore project, including its 822m-wide and 360m-high earth
dam, when it was officially commissioned on May 15, 1965, by
then prime minister Sir Keith Holyoake for the New Zealand
Its present owner, Meridian Energy Ltd, is undertaking the
first total refurbishment and upgrade in 43 years.
That will increase the power station's output, as well as
making sure it is reliable, provides the best performance
possible, is cost-effective and ensures the asset lasts for
generations to come.
It will also improve Benmore's integration with wind power
projects Meridian is planning in the South Island.
At the time, Benmore was the biggest project undertaken in
New Zealand by the Ministry of Works and, at that time, was
one of the largest dams in the southern hemisphere.
All six turbines, which generate up to 90MW each, will be
back producing electricity by December 2010.
Some work not part of the powerhouse upgrade will continue
It is a mammoth and complex job, employing an average of 40
to 50 on site each day under the project direction of Alan
Bulling and Associates.
The main contractor is Transfield Services and there are four
The Benmore upgrade is part of Meridian's ongoing programme
to refurbish its core hydro assets and get the best out of
Work started at the beginning of this year and so far has
included upgrading the two cranes in the powerhouses used to
lift and dismantle the turbines - some parts weighing up to
about 220 tonnes - to specifically designated areas within
When the Benmore power station was built, areas of the floor
were specially strengthened to take the weight of various
components of the turbines.
Now, work has moved on to upgrading and improving each of the
six turbines which generate the electricity.
As each one is taken out of commission to be worked on, that
will still leave five machines to continue generating
Most of the major work is being done on site, with some
pieces shipped to outside contractors.
The first turbine, machine 5, has been dismantled from the
pit in which it sits.
It will take about five months to complete the refurbishment
and upgrade, then two weeks to run it in and check it.
Once the first turbine has been completed and is
commissioned, lessons learnt from that will be applied to the
remainder and the process will speed up, taking four to 4
The next in line is machine 2, followed by 4, 3, 1 and 6.
Once completed, the turbines will use 5% less water to
generate the same amount of electricity before the upgrade.
That will add about 70GWh a yearin generation production to
Benmore's current 2200GWh - enough to power up to 8750 homes,
through more efficient turbines with the latest technology.
The work on the turbines is a mixture of maintenance,
refurbishment and incorporating the improvements in
technology that have been made in the 43 years since Benmore
As well as increasing the generating capabilities, the work
will also resolve cavitation problems that have existed since
they were installed.
That will end the two to three weeks maintenance needed on
each turbine and reduce the amount of time they were not
available to generate.
This is the first major upgrade since the early 1990s, when
three machines were overhauled.
Equipment and parts have come from all around the world for
the project, from as far away as Japan, Jakarta and France.