Abstract
The Pubnico Point Wind Farm, located about 30 km south of Yarmouth, is the largest commercial wind turbine generation project in the Maritimes. First envisaged in 2001, the Atlantic Wind Power Corporation spearheaded the project, acquiring a portion of funding through the Government of Canada's program "Wind Power Production Initiative" or WPPI,  | A view of Pubnico Point from the air, showing the
point encircled by fog. Click on the image to view a
larger image of the same. September 2005.
Courtesy of Atlantic Wind Power Corporation. |
and working closely with the provincial government of Nova Scotia were successful in the construction and deployment of giant wind turbines early 2005. The turbines are able to generate over 100,000,000 KWh annually, enough energy to satisfy the energy needs of 13,000 homes. This article shall describe the wind farm in general terms, including turbine specifications and photographs purely from an educational perspective.
Overview
The wind power plant or wind farm is composed of 17 giant wind turbines, Vestas V80, manufactured by Vestas Wind Systems A/S in Denmark. The turbines were installed in two phases. The first phase, installing only the first 2 turbines, completed in May 2004, commissioned in June 2004. The second phase included the rest of the 15 turbines, completing the installation in January 2005, commissioned May 2005. The renewable energy each turbine is able to generate is approximately 1,800 kilowatts, with a total accumulation of energy generated approximately 30.6 megawatts. This equates to a reduction of approximately 90,000 tonnes of carbon dioxide emissions (greenhouse gases or GHG) a year.
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Construction
Given the giant sized components, transporting them to the site were done in stages. The rotors, nacelle and hub were transported by ship and truck, while the towers were transported by rail and truck. All components were transported to Nova Scotia by ship from Europe.
In order to construct the wind farm, a significant amount of work was required to prepare the site for their installation. Before the site was considered, there was much analysis required in terms of measuring wind speed and direction over the course of a year. The data collected was important in determining the potential wind energy that can be derived from turbines installed in that location. This was done by installed anenometers at approximately 60 ft in height from the ground to simulate the height of the wind turbines. Other studies of the location included geotechnical assessment of the substrate (the ground) to determine if the earth was stable and dense enough to support the heavy turbines and their towers. Once the site was determined to be acceptable, another challenge was to map out the harbour between West Pubnico (the wind farm site) and East Pubnico for the purpose of laying submarine cables which will be transmitting the power generated by the turbines to the grid. The last major work in the site preparation was the construction of access roads, so that not only heavy equipment can enter the new site, but as well as the giant turbine components which will arrive on large flat-bed trucks.
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| Photos below depicting construction of the Pubnico Point Wind Farm site courtesy of Atlantic Wind Power Corporation. |
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| A view of a flat-bed truck prepared to transport two hubs. Click on the image to view a larger image of the same. |
A view of one of the blades of the rotor being loaded onto a flat-bed truck for transport. Click on the image to view a larger image of the same. |
A view of the interior of one of the tower's foundation. The scale of the cynlinder can be appreciated in relation to the size of the workers. Click on the image to view a larger image of the same.
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After most of the preparatory work was nearing completion, work began on the construction of the foundations on which the towers would be installed. These were essentially 10m diameter cylinders, approximately 30m in length which must be buried in the substrate to offer the turbine towers a solid base. These cylindrical foundations were integrated with 122 reinforcing bars attached to the foundation's base ring extending above through the foundation extending beyond the surface as threaded rods in order to receive the tower base flange which is then secured in place with large nuts. These foundation cylinders are then filled with cement offering the wind turbines an immensely solid and secure foundation. |
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Assembly
The first step in the assembly of any wind turbine, be they giants such as the ones in Pubnico Point, or small wind turbines that have rotors 2m in diameter, is the assembly of the tower. The tower services two fundamental wind turbine principles: a) provide a supporting structure for the spinning turbine rotors above the ground; b) position the rotors high enough to capture good laminar wind above obstacles such as trees or buildings to ensure it operates at peak efficiency. The assembly of the tower begins with the tower base. This base is fitted with a flange with holes to receive the ends of the threaded reinforcing rods protruding from the surface of the cement foundation. This portion of the tower has a diameter of approximately 4m and a height of approximately 12m. Interestingly, the weight of this bottom section of the tower is roughly 48 tons.
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Facts and Figures
The rotor assembly:
- diameter: 80m / 264ft
- speed (revolutions): 15.5 - 16.8 rpm
- power regulation: pitching of the blades using OptiSlip (a proprietary Vestas Wind Systems A/S computer based control system)
- material: glass-fibre reinforced epoxy
- weight: 39 tons
The wind turbine assembly:
- hub height (approx): 78m / 258ft
- overall height (top of blade): 118m / 389ft
- tower: bottom section: 48 tons, 13.2ft - 12ft in diameter, 37ft long
- tower: section 2: 51 tons, 12ft - 11.4ft, 56ft long
- tower: section 3: 51 tons, 11.4ft - 9ft, 78ft long
- tower: top section: 43 tons, 9ft - 7.6ft, 80ft long
- nacelle: 68 tons
- number of steps to climb tower: 270
Other wind farm facts:
- Largest commercial wind farm in the Maritimes.
- Annual production of 100,000,000 KWh of energy sold to Nova Scotia Power.
- The production of this energy displaces annually, approximately 90,000 tons of CO2 (carbon dioxide), 1,300 tons of SO2 (sulfer dioxide) and 250 tons of N2O (nitrous oxide). These are collectively called "greenhouse gases" or GHG. This is equivalent to NOT driving 16,000 cars for one year and has the same impact as planting almost 750,000 trees which would absorb the CO2 for 60 years.
- The renewable clean energy generated by the wind farms is able to supply approximately 13,000 average Canadian homes.
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More photos:
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| A view of the inside of one of the wind turbine towers. Click on the image to view a larger image of the same. Photo courtesy of Atlantic Wind Power Corporation |
Note the protrubing reinforcing threaded bolts through the flange of the tower base secured down with large nuts. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada. |
A view of the rotor above from directly below it against the base of the turbine tower. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada.
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| The turbine towers can be seen above the trees as one approaches the wind farm on 335 south. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada. |
Another shot of the turbine towers clearly visible above the trees. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada. |
A view of some of the turbines from ground level. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada.
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| A good photograph which adequately demonstrates the size of the wind turbine as compared to the car bottom left. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada. |
A view of the turbine's nacelle component from the rear. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada. |
A view of three majestic wind turbine towers oriented towards the sea. Click on the image to view a larger image of the same. Photo courtesy of SOLAR WIND Canada.
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In closing...
The wind turbines are impressive, standing amongst the forest on Pubnico Point, dwarfing the trees as the giant Douglas Firs drawf the forests in the west coast. Despite the giant size of the turbines, it was surprising how little unwanted noise emanated from the turbines. In fact, the sound of the wind through the trees was louder and nearly indistinguishable from the turbine's "swooshing" sound emanating from the revolving turbine rotors. Although, when positioned behind the rotors, there was a slight "whistling" sound, which emanated from the tips of the rotor blades. However, by increasing the distance from the turbine by 50m, these sounds were not detectable above the sound of the wind.
The wind farm is a testament to the growing interest and desire to generate clean and renewable energy. The increase demand for electrical energy will not cease, and power companies across Canada need to address this increasing need with methods of power generation which no longer rely on traditional methods such as coal-burning power plants or nuclear power plants. It is assumed that if Nova Scotia Power approached the residences in Pubnico with a proposal to build a nuclear power plant to service the increasing energy demand, it is obvious by virtue of the wind farm, that the general population would not accept traditional, environmentally unfriendly power generation solutions.
SOLAR WIND Canada Inc.
March 22, 2006
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