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A company specialising in modestly sized wind generation projects demonstrates how to capitalise on smaller sites with strong wind resources and existing distribution lines. By Alan Titchall.
That project, the Weld Cone wind farm, is now up and running and supplying power directly into Marlborough’s distribution network for Meridian Energy on a three year, fixed price contract, and producing sufficient power for around 300 homes per year. Engery3 is a private company developing wind farms on a small scale (one to five megawatts) that link into the numerous 11kV line systems around the country. “Our experience is that economical wind projects can be achieved by reducing capital and operating costs and managing electricity price risk,” says Engery3 director Ken Humphrey, adding that the Weld Cone project has a healthy return. “All projects go through a tight screening criteria. At Weld Cone, the site has an elevation of 330 metres, the connecting lines were less than half a kilometre away, the wind was between 10 and 11 metres a second, site access is good with access for a 220 tonne crane,” he says. “Our approach to land owners is a little different to most. At one level we do a royalty regime, much the same as other developers, but at Weld Cone the land owners were also interested in coming into the project in a joint venture. “We also organised a service agreement with the land owner for ongoing routine maintenance – so the land owner gets three sources of income from the project.” Humphrey says wind assessment was undertaken by mesoscale modelling (numerical weather prediction - the basis of modern weather forecasting) by Aurecon. “We didn’t use wind masts as we were sure that the wind speed at this location was in excess of 10 metres per second and at those levels we know we have a commercially viable project.” Putting up a wind mast for a year to confirm wind resource would have also added another $50,000 to the project’s cost, he says. One unique site challenge was the number of radio towers and microwave dishes in the area. “So we went to Kordia who did some analysis and found, quite peculiarly, the site was right in between the fresnell zones.” While a new road had to be built to the site, Engery3 found the EECA’s guidelines specifying consenting issues during the construction stage, commissioning and operational stages, very useful, Humphrey adds. Wild and woolly stuff
“Energy yield calculations accommodated topographic, inflow angles and other effects. The gradient of the hill up to the site is about 45 degrees so the angle for the wind is quite steep. “The angle results in a lot of wind acceleration. Survival wind speed on the location is 65 metres per second, strong by modern standards. This required engineering foundations to meet these requirements.” These site foundations were designed in Christchurch. “If you bring in equipment from overseas you still have to do the engineering to suit the NZ building code,” Humphrey comments. The turbines are second hand. “If we had used new machines the installed cost would have been in excess of $3000 a kilowatt, taking it to a lower return, which is not commercial for a small private company like ourselves.” Two turbines were bought from Germany and another from Denmark, which had already been in service for about 15 years. These were “rugged” Micon 530 models first installed in Europe around 1993. With only a certain amount of consented land left in Europe, operators there are replacing smaller machines with larger ones, so there are many such machines on the market. “With the high cost of bulk shipping in mind we deliberately looked for turbines that would fit inside a normal shipping container,” says Humphrey. The turbines were stripped down in Christchurch with different parts going to different contractors for reconditioning. For instance, the generators received new bearings by ABB, the gearboxes were overhauled with new bearings by Duralloy, and the blades were refurbished by Reflux. “All refurbishments were done locally in Christchurch with an amazing range of skills. I wasn’t aware you could even make gears for these machines here.” With the turbine chassis sandblasted and repainted, these wind turbines were, “pretty much new,” he says. Project management
“It is less costly to manage centrally. We even arranged our own shipping, customs clearing and freight forwarding to import the turbines,” he says. Consultants are used for specific technical tasks only. “Putting together a small scale wind farm is a reasonably straight forward process but it’s important to maintain management on a day to day basis and to maintain ‘stage gate’ project disciplines,” he says. Consenting is linked to all aspects of the project and should not be considered a separate activity, and working with the landowner and community is critical and cannot start early enough, he adds. “The devil is in the detail. Project viability must be constantly reviewed, and with regular checks on economics and financing.” Engery3’s general outlook for future projects around the country is very positive says Humphrey. “Wind resource and energy is abundant in New Zealand and distributed generation makes sense, given our geography and electricity transmission systems.” Of particular interest are projects that have an existing electricity load such as irrigation or industrial works. “In these cases, the landowner or power user benefits by being able to purchase electricity at a price below the price from their retail supplier. The landowner or power user can both reduce their electricity supply costs and ‘fix’ the price of electricity over the life of the wind farm project. “This is particularly valuable if the landowner believes that electricity prices will increase.” Energy3 is currently working with two industrial firms on just this concept – in addition to working on a further five development projects in the South Island. The most advanced of the Energy3 developments is Lulworth, a 1 MW project in Marlborough, which obtained a resource consent earlier this year and is planned to be commissioned by the end of 2010. Energy3 also provides wind measurement and monitoring services to the New Zealand, Australian, and South Pacific wind industries. These include supplying and commissioning wind monitoring masts up to 80 metres high, managing LIDAR systems, monitoring wind data quality, maintaining instruments and masts as well as providing analysis of wind resources.
Energy NZ Vol.4 No.4 July-August 2010 |
In May 2009 Energy3 received the go ahead from the Marlborough District Council for a small, three-turbine wind farm near Ward in the right hand corner of the top of the South Island. The consent allowed for a maximum of three turbines with a height of 75 meters (including blades) with a total installed capacity of 1.5 MW.
Positioning of the turbines and energy analysis was complicated, Humphrey concedes, and sophisticated analysis had to be used to get an angle on predicting energy yields.
With a background in project management Humphrey says the Weld Cone wind farm was a disciplined exercise in the same way as any large corporate project.