Putting the wind to work for Ontario
|
The Prince Wind Farm will be the first large-scale development of its kind in Ontario. It is located primarily in the township of Prince, 10 km northwest of Sault Ste. Marie, Ontario. The project is Brookfield Power’s first wind energy development. The project site was selected for its:
As Owner’s Engineer, Hatch Acres is responsible for all civil engineering components, as well as most environmental aspects during the preliminary engineering, design and construction stages. Our partner/consultant for electrical engineering is Breton, Banville & Associates (BBA) of Quebec. |
Brookfield Power originally intended to establish a single Engineer, Procure, Construct (EPC) contract with the turbine supplier who would in turn subcontract all other balance of plant (BOP) activities. However, in the preliminary engineering phase, Hatch Acres/BBA identified significant potential savings by implementing three separate BOP contracts for each of the turbine supply, civil works and electrical components. This recommendation was approved and adopted.
Site design
Wind farm construction is far more complicated than many people realize. Not only must adequate winds be present over the site’s entire acreage, but the net effects of each turbine must be accurately determined in order to set the ideal location and separation of all units for optimal space usage and power generation.
The Prince site’s wind resources have been measured since 1998, while more concentrated monitoring and analyses were conducted in the last three years. Meteorological data was collected at various heights from three anemometer towers and compared with long-term data from nearby Coast Guard instruments. Data was also collected around the site with sonic detection and ranging (SODAR) systems which remotely measure vertical turbulence structure and wind speed up to 200 m above ground level. The SODAR and anemometer data were calibrated to develop a comprehensive understanding of the wind regime prior to siting the turbines.
Phase I development involves installation of 66 turbines with a generating capacity of 99 MW, while Phase II will include 60 units for an additional 90 MW. The total project will therefore consist of 126 wind turbines with a combined capacity of 189 MW.
The turbines are GE’s three-bladed Sle model, each with a generating capacity of 1.5 MW. The turbine generators and nacelles will be mounted on 80-m (rotor hub height) steel tubular towers. With a diameter of 77 m, each unit’s rotors sweep 4,657 square meters at speeds between 10 and 20 rpm. The induction generator operates at 600 V, and a pad-mounted transformer located near the base of each tower interconnects with the 34.5-kV buried collection system. A fibre optic network links each turbine with the site’s Supervisory Control And Data Acquisition (SCADA) system for remote monitoring and control from the collector substation.
Challenges
While Prince’s terrain is ideal for its wind resources, it was not necessarily ideal for construction. Wind developments in North America are often built on farmland or other relatively flat land. The rugged bedrock conditions at the Phase I site, however, presented an entirely different set of circumstances.
|
The site is situated along a southwest-to-northeast ridge parallel to the Lake Superior shoreline, with elevations up to 400 m above sea level. The area is within the rugged Canadian shield with forested and undulating terrain. The bedrock has extremely high strength, and lateral variations in depth of 3 m or more were not unusual across the width of the Phase I access roads, as well as across the width of a tower foundation. These conditions required significant blasting and excavation for road and foundation construction. Initial results from geotechnical investigations on the Phase II site are more favorable, and rock excavation requirements will be significantly lower than on Phase I. |
The Phase I turbine tower foundations were poured between November 2005 and March 2006. Concrete supply, conveying and placing requirements under cold-weather conditions were the most critical components of the Hatch Acres technical specifications, requiring strict adherence by the contractor. Our daily on-site monitoring of construction ensured that all concrete was kept above freezing temperatures for a specified minimum interval after placement. This was essential to ensure structurally sound concrete meeting minimum compressive strength parameters.
Environmental stewardship has also been a key ingredient throughout the development. All activities, from planning through to construction, have incorporated mitigation measures to protect the integrity of wetlands and watercourses. Monitoring of wetlands and watercourse crossings has included ensuring drainage characteristics and features are maintained and ensuring adequacy of contractor’s sediment controls. Bird and bat populations have been monitored with radar and acoustic techniques throughout the site since 2004, and a census for the various species was compiled. While their habitat and flight routes were taken into account when siting the wind turbines, monitoring will continue during construction and wind farm operation. |
|
Status
Since Phase I construction began in September 2005, Hatch Acres has provided full-time civil and geotechnical services on site. Access roads, and foundations (octagonal concrete spread footings, 16 m in diameter) for the 66 towers, have been completed, as well as an 11-km long, 230-kV overhead transmission line from the collector substation to the power grid connection point. The Phase I 34.5/230 kV collector substation is currently under construction, with the main transformer being placed on its foundation during the first week of May 2006. Delivery of the wind turbines/towers for Phase I is scheduled for May 2006, with turbine and tower erection and commissioning to be complete by fall 2006.
|
Construction of the Phase II roads began in February 2006. The 60 turbines/towers will be delivered starting in August 2006, with turbine erection and commissioning to be complete by the spring 2007. The overall schedule is aggressive but achievable, with good progress made so far. When complete, the Prince Wind Farm will supply power to a 230-kV Great Lakes Power Limited transmission line to the east, adding approximately 535,000 MWh annually of renewable energy production – roughly equal to the annual consumption of 40,000 average Ontario homes. |
For further information, please contact:
|
Murray McFarlane |
« Back to the newsletter listings