Pipes from the Manapouri tailrace tunnel are currently being prepared for use as the pen stock line in the restoration of the Onekaka power scheme. The Onekaka site began generating power in 1928 when the old Iron Works was operating but stopped generating in the 1950's. Local groups are resurrecting it on the basis that New Zealand requires more embedded power generators scattered around the country.
Kidson Construction are the project managers, and Brian Kidson explained how some power transmission lines on the national grid are reaching capacity. "They are here in Nelson, they will be around Gisborne and Northland, and so more embedded generation is a good thing. I think there are two issues for any country in the 21st century, and one is water and the other is power. Those are the two essentials which may be in short supply."
"We have been in the construction industry for almost 40 years now and we have most of the skills that are needed between ourselves and our sister company Kernohan Engineering, and the scheme initiator Jim Baird of Clifton Engineering," Brian said.
The proponents of the scheme began the consents process for the one megawatt plant in 1992-93, and it has taken almost seven years to get all the consents ironed out. "We hope to have power on line by next winter," Brian said.
A certain amount of damage was sustained in removing and transporting the secondhand pipes out of Deep Cove, with repairs needed to some pipe ends for sound coupling seals, and some dents needed removal. Also inside many pipes there were calcium type deposits, as they had been water discharge pipes from dewatering the face of the second Manapouri tailrace tunnel.
The cleanup of these 60, 12m long pipes (in three diametres of 400, 500 and 600mm) was the responsibility of project developer Peter Chapman of Kidson Construction, who admitted it was a 'number 8 wire' type thing. "We knew what the problem was, and came up with a solution."
"We designed a system to clean them - a rotary flail with a decent sized motor to get inside the pipes. We had to design something that would pull through and get wound back, for which we used a boat winch for the smaller 400mm diametre pipes. The bigger ones we could use a water head, a powerful water jet. But the little ones had a bigger buildup of deposits, some up to 30mm in places, and our flail just gets pulled through and churns it out, and it comes out shiny."
"The bigger ones, the guys climbed inside and pushed the dints out with a jack, the ones we couldn't get inside we welded a strong back on the top and pulled them out from the top. The ends have to be trued up, and we have made a mushroom-type press die to straighten them. We are really happy with the results we have been able to achieve," Peter described.
According to the project initiator, 60 year old Golden Bay resident and mechanical engineer Jim Baird, it's high time the government and local authorities got in tune with the rest of the world and allowed independent power generators to economically supply power to the local grid. Jim has been involved with distributed power generation for most of his life. Starting out in farming, he had his own turbine, a Francis turbine and a Carnival generator which his father installed on Ellis Creek, which supplied the farm, until the public supply came. Jim was also instrumental in forming a society to rescue the Pupu power station from destruction, which has subsequently been running successfully for over 15 years.
"I couldn't do much in those days, because 'the empire' wouldn't permit me," Jim explained, "the 1928 Power Boards Act was very draconian, it said thou shalt not generate power for public consumption. Right up to the end of the Muldoon era we had so many constraints put on us in New Zealand, where as in the rest of the world they could do what they liked."
This situation may be slowly changing however, as when the Minister of Energy the Hon Pete Hodgson, addressed the Electricity Networks Association AGM last month he said, "demand for electricity in New Zealand has been growing at a steady rate of 2% per annum for many years. If this rate of growth continues, we will need to build about 150 megawatts of new generation a year simply to meet demand and maintain an adequate dry-year reserve."
The minister also spoke of potential plans for more than 2,000 megawatts of capacity to be built in the next decade, but he did not accept that demand would continue to grow as it has in the past. "The government's commitment to a sustainable energy future should see gains in energy efficiency, and therefore generation capacity is not the only answer."
However Mr Hodgson continued that, "embedded generation, particularly renewables, will play a vital role in New Zealand's sustainable energy future. One of the government's goals is to facilitate the use of new electricity technologies, renewables, and distributed (embedded) generation. We want to ensure there are no barriers to their use. If pricing methodologies are unduly harsh on embedded generation, it won't be built."
Jim Baird feels strongly that the government should do what every other country on earth does. "That is implement a little regulation, whereby the incumbent electricity retailer is forced by law to buy power from the embedded generator at the avoided cost at the grid exit point, at least 6c/Kw. But currently no-one wants to in the political world."
"I think the government is tearing their hair out at the moment trying to find a solution, because a lot of pressure is coming on them from wind powered generators, with independent people that are wanting to set up wind generators."
