The History of Carleton's First Wind Turbine

Saturday, September 25, 2004 marked the dedication of Carleton's 1.65 megawatt wind turbine, the first utility grade wind turbine in the country to be owned by a college. Though the turbine was constructed with amazing speed in August 2004, the process of developing a green energy plan was much longer. The planning and building process is chronicled below.

Planning

In the summer of 2002, Northfield School District initiated a meeting with St. Olaf College, the City of Northfield, Northfield ReNew (a community based wind advocacy organization) and Carleton College to create a taskforce to explore the opportunity of developing wind energy. After the exploration of sites adjacent to the community, two ridges were found to be candidates for wind power. Only the school district and Carleton were interested in further developing a feasibility study to determine the costs, location and public acceptance of two industrial size wind turbines. An anemometer was erected on each of the ridges to measure the wind and determine the size of turbine would produce the most power for the sites. Carleton and the school district together hired a wind developer to assist in the development of the project.

Early in the exploration, Northfield ReNew held a public meeting to talk about Carleton and the school district’s tentative plans to buy and operate wind turbines. More than 90 community members attended the meeting, and except for a few who were worried about bird kills, the initial acceptance of the idea was universal. About nine months later, a public polling firm asked Northfield residents about wind power in conjunction with a school referendum. The survey indicated that there was a high acceptance of the school district developing wind power—80 percent agreed to it if it were to make money. Unfortunately, the Northfield school district was unable to pursue this project.

After a substantial amount of wind data was collected, a formal bidding process for the best turbine was conducted. Because of the slightly slower wind speed in this area than in western Minnesota, a NEG Micon, NM1.65MWx82M rotor span with 40 meter blades was selected and used for the cost estimate and creation of a development scenario.

Proposal

The development and construction of a 1.65 Megawatt wind turbine located approximately 1-1/2 miles east of Carleton College in cooperation with the Northfield School District. This wind turbine will be a utility grade wind turbine. The height of 360 feet is the top of the swept area of the rotor span, usually described by the Hub Height -- which is 230 ft (70M) and the rotor span is 270 ft (82M). The blades are about 132 ft (40M) in length. The rotor span is larger than older turbines located in strong wind areas such as southwestern Minnesota. The larger span is technologically more efficient at gathering energy from the lower average wind speed in the Northfield area.

This installation will be an important demonstration of current low wind technology, which allows wind production to be located in much broader geographic areas and closer to the electrical loads being served. The wind turbines will be interconnected directly into Xcel’s distribution lines. This type of interconnection is an example of what is called Distributed Generation (DG). Distributed generation is simply generating energy close to the areas where it can be readily used. In our case, the energy from this turbine will flow into the Northfield electrical grid and be used locally. Rather than generating energy miles from the source and building high voltage electrical transmission line, the energy can be incorporated into the existing electrical network. Xcel is willing to buy the produced energy for 3.3 cents per kilowatt-hour for all energy produced. This energy price can be contracted at a fixed rate for 20 years. The College will have to pay for the cost of the turbine, land lease, transmission lines to the distribution line, interconnection equipment, transformers, property, and business interruption insurance, taxes, and maintenance. The estimated kilowatt-hour per annum of a 1.65 Megawatt turbine is approximately 5,000,000 KWH.

Process schedule

  • September–November 2003: Develop a memorandum of understanding with the Northfield school district.
  • November 2003–January 2004: Develop the ballot for the school district referendum
  • December 2003: Apply for federal production credits
  • January 2004: School district vote on the wind energy issue (School district was unable to proceed with project)
  • February 2004: Develop and distribute a bid document for a wind turbine
  • February 2004: Apply for conditional use permit from Rice County
  • March 2004: Select a wind turbine and place order for wind turbine
  • August 2004: Turbine delivery and installation
  • September 2004: Begin production of green energy

Project schedule

  • August 4: Foundation completed
  • August 13: Turbine arrives in Houston
  • August 27: Pylon tower arrives on site
  • August 27: Turbine arrives on site
  • August 27: Base section of the tower set
  • August 30: Turbine prepared for installation
  • September 1: Tower is completed
  • September 1: Turbine and blades are installed
  • September 3: Electrical work is completed
  • September 13: Connection with Xcel Energy is completed
  • September 15: Wind turbine is commissioned
  • September 16: Turbine is supplying energy to the grid
  • September 25: Wind turbine dedication

Why Wind?

The mid-continent portion of the United States is blessed with an abundance of wind resources. Since 1981, 4,250 megawatts of wind energy have been developed in the U.S. Since the mid 1990s, utilities and farmers in southwestern Minnesota have mined this wind resource, producing 336 megawatts. Another 259 megawatts is expected to be installed in the next years. Xcel is producing over 308 megawatts of electricity or almost 3.75 percent of Xcel’s energy portfolio.

Two technological factors have changed in the last 10 years that allow the area around Northfield to be a fertile wind resource. First, the design of industrial grade wind turbines has progressed to a point where they can capture energy at a lower wind speed. Although the winds around Northfield are not as strong as in the southwestern portion of Minnesota, with the new technologies, turbines have become economically feasible. The second factor is linked to the first. With the development of the wind resource, not only have the turbines become more efficient, but turbines have shared in some economies of scale and therefore are cheaper. In 1980, a wind-generated kilowatt-hour cost almost 40 cents to produce. Currently the same kilowatt-hour costs about 4 cents to produce.

Environmental Impact

Carleton’s environmental impacts are as follows: One 1.65 megawatt turbine would replace about 40 percent of our total electrical load with green non-polluting energy. A 1.65 megawatt turbine would reduce noxious emission of greenhouse gases in the amount of:

  • CO2 (Carbon Dioxide): 4,318.1 (tons)
  • VOCs (Volatile Organic Compounds): 170.8 (lbs)
  • NOx (Nitrous Oxide): 11.6 (tons)
  • CO (Carbon Monoxide): 1,665.8 (lbs)
  • SO2 (Sulfur Dioxide): 11.5 (tons)
  • PM10: 1,223.9 (lbs)
  • Mercury: 0.1 (lbs)

The Danish study for the Ministry of the Environment also estimated that a coal-fired power plant emits 360 times more SOx, NOx, and carbon dioxide to generate an equivalent amount of electricity over the 25-year life of a wind turbine. Over the life of Carleton’s turbine, it is estimated that the College would reduce CO2 by 1.5 million tons.

Opportunities

This wind turbine development presents the College with incredible educational, environmental, and economic opportunities.

Educational Opportunities:

With each of the turbines there is a computer interface. The data relayed to the computer tracks and displays the wind speeds at each moment, the amount of energy being generated, and the capacity of the turbine. The physics department can study the mechanical aspects of the turbine and the generation of energy with the power of the wind. The kilowatt-hours can be instantaneously translated into reduction of greenhouse gases. These emissions can be tracked and accumulated over time. This will allow a learning station to be set up in the physics department’s gathering area where students can access data generated by the turbine as well as information about how the turbine works and why wind power is important to Carleton and the region. Faculty may also offer a tutorial about green energy and the efficiency of the very methods of green energy. Each type could be compared and contrasted as to their effectiveness and environmental footprint.

Environmental Opportunities:

In the United States, approximately 6.6 tons (almost 15,000 pounds carbon equivalent) of greenhouse gases are emitted per person every year. And emissions per person have increased about 3.4% between 1990 and 1997. Most of these emissions, about 82 percent, are from burning fossil fuels to generate electricity and power cars.

Economic Opportunities:

In addition to Xcel’s monthly payments to the College for energy purchased, the college qualifies for a Minnesota Production Credit of 1.5 cents per kilowatt-hour for a 10-year period.

Another potential source of funding is the Federal Production Credit, if approved. This is an alternative to the Federal Tax Credit for non-profits. The production credit is approximately 1.8 cents per kilowatt-hour for 10 years. There is no limit to the amount of funding for the credit but the government is not required to reimburse the applicant fully, though to date, all applicants have been fully funded. This credit is funded annually.

Frequently asked questions about the wind turbine.