Bent Tree Wind Farm:

In October 2009, Wisconsin Power and Light Company (WPL) received final regulatory approval to develop Phase One of the Bent Tree Wind Farm in Freeborn County, in southern Minnesota.

The Bent Tree Wind Farm site has the potential to produce up to 400 MW of emissions-free energy if completely developed. That’s enough energy to power approximately 100,000 homes. Phase One will develop 200 MW of wind power (enough to power approximately 50,000 homes) on the site. Commercial operation is anticipated in 2011. A decision regarding the development of the wind farm’s additional 200MW has not yet been made.

Bent Tree Wind Farm will sit on approximately 32,500 acres in northwest Freeborn County, about four miles northwest of Albert Lea, Minnesota. WPL will design, build, finance, operate and maintain Bent Tree Wind Farm. The energy generated by Bent Tree will serve customers in our Wisconsin service territory.

Wind Farm Facts | News Releases | Questions and Answers

 

Bent Tree Wind Farm Facts:

  • The wind farm spans approximately 32,500 acres
  • Approximately 150 landowners will participate in the project
  • Each wind turbine will be capable of producing approximately 1.65 megawatts of emissions-free energy, the equivalent of powering approximately 400 homes
  • Approximately 122 turbines will be constructed and installed in Phase I
  • Height of turbine from base to tip of blade pointing straight up = 397 feet
  • Distance from the ground to the hub = 262 feet
  • Each blade is approximately 131 feet long
  • The blades will be made of fiberglass-reinforced polyester or wood epoxy
  • The towers will be tubular and made of rolled steel
  • The concrete foundations will measure approximately 50 feet wide by seven feet deep
    • Approximately 450 cubic yards of concrete, which equals approximately 50 concrete mixing trucks
  • Power generation begins at 9 mph with a maximum power generation of 47 mph
  • The wind turbines will produce power approximately 90 percent of the time,  depending upon sustainable wind speeds
  • If completely developed, Bent Tree Wind Farm will employ between 18-25 employees
 

News Releases:
Wisconsin Power and Light Company purchases development rights to Bent Tree Wind Farm - 3-23-09

Wisconsin Power and Light Co. moves to expand wind generation - 6-6-08

Wisconsin Power and Light Co. makes wind filings in Minnesota - 6-30-08

Wisconsin Power and Light Company moves to purchase wind farm development site - 4-22-08

 

Questions and Answers:
When did WPL purchase the development rights to Bent Tree Wind Farm?
On April 22, 2008, we executed a letter of intent to purchase the development rights to Bent Tree Wind Farm from Wind Capital Group, LLC, a St. Louis, Missouri based developer of wind energy assets. WPL closed on the sale March 20, 2009.

Why was WPL interested in this site?
Alliant Energy is committed to maintaining our strong renewable presence in the state of Minnesota. The decision was made to develop the Bent Tree site because of the strong and persistent prairie winds of southern Minnesota. This wind resource enables the company to generate more wind energy for its Wisconsin customers in a cost effective manner. As Alliant Energy continues preparing for the future, this site provides “room to grow” as we expand our renewable energy portfolio.

How much electricity will be generated by Bent Tree Wind Farm?
Bent Tree has the potential to produce up to 400MW of emissions-free energy if completely developed. That’s enough to power approximately 100,000 homes. Phase 1 of the project consists of 200MW, which can provide enough electricity to power approximately 50,000 homes.

Who will receive the power from Bent Tree Wind Farm?
The electricity generated at Bent Tree will be sent out over the electric transmission grid to reach areas within Wisconsin where electricity is needed at that time.

How many turbines will there be at Bent Tree Wind Farm?
There will be approximately 122 turbines built and installed for Phase 1. They will be spread out over approximately 32,500 acres.

Where is the wind farm site?
The wind farm site spans portions of Freeborn County, about 4 miles north of Albert Lea, Minnesota.

Will my electricity supply depend on the wind blowing?
No. All customers will continue to receive a constant flow of electricity from WPL. As wind-powered electricity is added to the grid, other generators will be turned down or off to maintain the balance.

What type of turbine will be used?
Vestas V82 turbine that is capable of producing 1.65 megawatts of electricity will be used at Bent Tree Wind Farm.

What type of lighting will need to be around the wind turbines?
There will be no base-level lighting on or around the wind turbines. The only lighting on the wind turbines will be mandatory FAA lighting on the top of the wind turbine nacelle.

Will the wind turbines produce noise?
Wind turbines only produce measurable noise when they are operating, but it is not disruptive to most people in most situations. An operating modern wind generating site at a distance of 750 to 1000 feet creates the same amount of noise as a kitchen refrigerator. You can stand directly beneath a turbine and have a normal conversation without raising your voice. Typically the sound of blowing wind is louder.

Will the landowners still be able to use the land around the wind turbines?
With the exception of a 50’ x 50’ parcel directly surrounding the wind turbine’s base and a narrow access road, landowners will be able to utilize all the land surrounding the wind turbine. Many farm roads can double as access roads, reducing non-usable land even further.

Who is managing construction of the wind farm?
WPL will manage the wind farm construction.
 
Costs and Economic Impacts:

Will Bent Tree Wind Farm help the economy in Freeborn County?
When fully developed Bent Tree Wind Farm will pay more than $1,000,000 annually in taxes to Freeborn County which is equivalent to 6.5% of the current county budget.

What will Bent Tree Wind Farm cost?
The initial 200MW phase of the project will cost approximately $425 to $475 million, excluding allowance for funds used during construction.

Environment:

What are the environmental benefits of wind power?
Wind power benefits the environment because it does not create any emissions or deplete natural resources, such as wetlands and animal habitats

How will Bent Tree Wind Farm benefit the environment?
By offsetting the need for traditional fossil fuel generation, Bent Tree Wind Farm will significantly benefit the environment. When completely developed, Bent Tree is expected to reduce annual air-emissions as follows:

  • Sulfur dioxide (SO2) reduced by approximately 1,500 tons
  • Nitrogen Oxide (NOx) reduced by approximately 700 tons
  • Mercury (Hg) reduced by approximately 30 pounds
  • Carbon Dioxide (CO2) reduced by approximately 500,000 tons, which is equivalent to:
    • Removing 75,000 cars from the road for one year
    • Accumulating electric energy savings equal to powering 35,000 homes for one year

Will Bent Tree Wind Farm harm birds, bats or other animals?
A risk analysis was completed during the project planning stages to determine potential impacts to animals that reside in the project area.  Threatened and Endangered species, birds, bats, and plant species were evaluated.  The results of this study are as follows:

  • No Threatened and Endangered species were previously known to exist within the project boundary and will therefore, not be impacted by the project. 
  • The presence of lakes, wetlands and wildlife management areas (WMA) in and around the project area provide habitat for nesting and migrating birds.  This represents a risk to waterfowl and other bird species, however a buffer zone has been created around the WMA to minimize the risk.
  • Due to the amount of cropland within and around the project site, and limited woodlands, the project is a low-risk for bat mortality.
  • It is not anticipated that rare plant species will occur within the project boundary as they are typically found in higher quality communities (i.e. prairie remnant).  The site is primarily cropland which would inhibit rare plant growth.

What other environmental studies have been performed for the project?
Additional studies for impacts to wetland areas, historic archaeological sites, noise levels, and communication equipment have been completed. These analyses concluded that wind turbine locations and collector lines will not disturb wetland areas. Crane paths used during the construction phase will have temporary impacts on stream crossings, however all stream crossings will be restored to their original state upon completion of construction.

Historic archaeological sites will be avoided and therefore not disturbed by construction activities. In the event that an area of concern is unearthed during the construction process, all activities will be halted and the appropriate state and local agencies contacted.

Noise levels for the occupied residences in the project area were assessed through a modeling analysis. Impacts were confined to the area immediately around each wind turbine structure. Predicted noise levels at each residence were in compliance with Minnesota regulations. Service interruption to radio and TV communication towers is not expected.

Project Timeline:

When will the wind farm be built?
Construction of Bent Tree Wind Farm will begin in 2010 and it is expected to begin commercial operation in 2011.