For Michigan-based Consumers Energy, the 100.8 MW Lake Winds Energy Park serves dual purposes. Not only does the wind farm help meet Michigan’s 10% by 2015 renewable energy standard (RES), but also the experience gained from building it will help the investor-owned utility’s future forays into wind power.
The wind farm, located in Mason County, is powered by 56 Vestas V100 1.8 MW wind turbines. The company says it chose the location after carefully studying 19 potential sites across the state, noting the region’s wind resource (estimated by AWS Truepower at 7 m/s to 8 m/s) and access to available transmission. The wind farm interconnects to the Consumers Energy high-voltage distribution system, which then interconnects into the Michigan Electric Transmission Co.-owned transmission system at a substation near Ludington, Mich.
Consumers spokesperson Dennis H. Marvin says Lake Winds has put the utility on track to meeting the Michigan RES. In fact, wind is the primary renewable energy source that Consumers is using to comply with the mandate: Wind energy accounts for more than 75% of the utility’s renewable energy portfolio, which includes more than 300 MW of installed capacity through power purchase agreements.
Shadow flicker and sound
The Michigan Zoning Enabling Act, established in 2006, allows cities and townships to decide for themselves how wind farms should be zoned. If the township does not have its own zoning standards, the act allows the township to defer to the county zoning ordinance, which was the case here. The project is located in Riverton and Summit Townships, neither of which has its own zoning requirements. Therefore, project development was subject to Mason County’s zoning laws, which Marvin characterizes as among the most stringent in Michigan, if not the entire U.S.
Before it was granted a special-use permit, Consumers had to prove that the wind farm would adhere to the county’s zoning rules for shadow flicker – which can occur when the rotation of wind turbine blades causes alternating periods of shadow and light, causing an intermittent shadow – and sound levels.
The Mason County zoning requirements stipulate that the wind farm cannot exceed 10 hours per year of shadow flicker on occupied homes or buildings. According to the utility, the project has been laid out to minimize shadow flicker.
Although some residences near the turbines may experience a few minutes of flicker per day, 94% will experience less than 10 hours per year – the maximum amount allowed annually.
To adhere to the zoning requirements, Consumers selected the turbine package containing Vestas’ proprietary Shadow Detection System – making Lake Winds the first U.S. site to employ the Vestas technology. The solution, which consists of two light sensors and a shadow controller, automatically shuts down the turbines in the event of a shadow flicker event.
According to Vestas, the system operates by using calculations for a potential receptor. The shadow controller uses a shadow flicker timetable for clear weather. If the calculations indicate the intensity of the sunlight is strong enough to cause shadow flicker, the turbine is paused for the remaining part of the shadow window. When the shadow flicker event subsides, the turbines are restarted, and the incident is logged.
As for sound levels, Mason County’s zoning ordinance dictates that decibel levels need to be less than 45 decibels at the property line, Marvin says, noting that many other jurisdictions set the level thresholds at a residence’s doorstep.
Additionally, given the project’s proximity to Lake Michigan, Consumers Energy filed an ice detection mitigation plan to prevent ice throw. According to Marvin, sensors on two hub-height met towers monitor signs of icing.
“Our operational procedure includes shutdown when [icing is] indicated, visual monitoring during daylight hours and confirming that ice is no longer on the blades before the turbines can be made available for service.”
However, the overriding challenge for the utility – and its supply chain partners – was to complete the wind farm in time to qualify for the federal production tax credit, which was scheduled to sunset by the end of 2012. Although the time frame was constricted by Michigan’s Frost Laws – which put restrictions on traffic weight and speeds on roadways during the end of winter – the project was minimally impacted, notes Marvin.
“Fortunately, we had a very seasonable winter that year, which enabled us to construct access roads and foundations through the majority of the winter months until the time Michigan’s Frost Laws were established, forcing us to suspend construction for about three weeks.”
Adding to the degree of difficulty was the decision to place the wind turbines in an orchard. According to Marvin, great care was taken to avoid damage to the fruit trees.
Unlike field crops, such as corn, which can be grown the following year, fruit trees can take years to replace to the point when they are yielding full production, he explains.
The Lake Winds project came online in November 2012.
However, the project’s hurdles did not deter the utility from more wind power endeavors. In fact, work has already begun on its 105 MW Cross Winds Energy Park, located in Michigan’s Thumb region. According to Marvin, before suspending construction for the winter last year, principal contractor Barton Malow had completed 18 access roads and 13 turbine foundations of the 62 sites.
“Given the severity of the winter we’ve had, the only work that continued during the season was on the construction of the project’s collection substation and O&M building,” he says, adding that construction of turbine foundations, access roads and the collection system will resume once Michigan’s Frost Laws are lifted. He anticipates turbine erection to begin by July and the wind farm to be operationally complete by the end of the year. w
Project Profile: Lake Winds Energy Park
Utility Builds First Wind Farm Among Strict Zoning Requirements
By Mark Del Franco
Consumers Energy battled stringent rules when building its 100.8 MW Lake Winds Energy Park, located in Mason County, Mich.
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