In January St. Louis County added wind power to the roof of the Government Services Center at 320 W. 2nd St. in Duluth.
The St. Louis County pilot project will use six turbines, each six feet in diameter and producing an output of one thousand watts. They will perch on the east edge of the rooftop to catch wind off Lake Superior. Being placed at the parapet enables the turbines to take advantage of the “chimney effect” of wind hitting the side of the building and traveling upwards at increased speed.
Rooftop micro wind turbines for urban and suburban settings are a fledgling technology.
They are still in the demonstration phase, used mainly by government buildings and large companies interested in green technology, said spokesman Stan Michelson for AeroVironment Inc., the company that provided the turbines for St. Louis County.
Founded in 1971 and based in Monrovia, CA, AeroVironment is perhaps best known for creating the first human-powered airplane, the Gossamer Condor. It has since developed solar-powered and fuel-cell powered cars and planes. It also makes unmanned aircraft for NASA and the military.
In 2007 the company installed 18 wind turbines on the roof of the Kettle Foods manufacturing plant in Beloit, WI. AeroVironment also has turbines on five other buildings in California, Texas, and New Jersey.
Meanwhile, Chicago-based Aerotecture International has placed rooftop systems in the Windy City on Mercy Housing Lakefront Near North Apartments, a new homeless shelter built with green design; on the law office of Magee, Negele & Associates; and on the new green-designed headquarters of Christy Webber Landscapes. Plans are in the works to install turbines atop the Daley Center.
Johnson Controls Inc. plans to include wind turbines, green roofs, and solar panels in the $54 million upgrade of its headquarters in Glendale, WI. The facility management company announced Jan. 18 that its fiscal first quarter profit rose 45 percent in part because of its offering to improve energy efficiency and greenhouse gas emissions on commercial buildings.
Construction on the St. Louis County project began Jan. 17, when a crane lifted sections of a 40-foot infrastructure support I-beam onto the roof. On the same day Minnesota Gov. Tim Pawlenty announced the state will offer up to $20 million in low-interest loans for businesses and homeowners to use renewable energy sources, including wind power.
A day later on Jan. 18, the American Wind Energy Association ranked Minnesota No. 3 in the nation for existing wind capacity and No. 9 for potential capacity. Minnesota produces 657 billion kilowatts per year through wind power and has 46 wind energy projects under construction.
The county hopes the turbines will shave costs from its $11,000-$12,000 per month electric bill. If it doesn’t produce results in the first year, the county has the option to move it to another county building, for instance, in Pike Lake or Hibbing, where it may be more productive, said Tony Mancuso, St. Louis County property management director.
Unlike residential electrical rates, commercial rates include a “peak demand” charge to meet the customer’s maximum 24/7 load requirement. “We pay $4.36 per kilowatt hour while a homeowner pays eight cents,” Mancuso said, noting the turbines should help reduce the peak demand charge.
The entire project will cost $51,100. Minnesota Power will provide an energy rebate of $6,000. The county also is applying for a rebate of up to $12,000 from the Minnesota Department of Commerce.
St. Louis County purchased the Government Services Center from the state in 2002. “The energy consumption for the facility due to the poor condition, design, and age of the electrical and HVAC systems is very high,” wrote Tom Romundstad, project manager for county property management, in a December 2007 letter to Minnesota Power.
County administration considered a larger scale wind energy project, but the cost, requirements, and permits proved “daunting,” Romundstad wrote. Instead, the county opted for the pilot project.
“We don’t know if it’s a good idea or a bad idea,” Mancuso said. It’s unknown how long it will take for the turbines to pay for themselves through savings. Romundstad conservatively projects the turbines will reduce costs $1,200 a year, but expects rising energy costs to reduce the payback period. He also projects they will reduce carbon dioxide output by 23,600 pounds annually.
The turbines’ power output will be monitored with data fed to the property management department’s Web site. A weather station also will be installed on the roof with conditions posted on the Web site.
Large windmills have raised debate over whether they kill birds. The issue is less of a concern for micro turbines. “In the six year operational history of these units there has been no reported or documented bird kills,” Romundstad wrote. The turbines on the county building have canopies to keep birds away from the blades.
Wind turbines are among numerous ways St. Louis County has turned to renewable energy for its buildings. The county’s goal is to reduce energy consumption by 20 percent per square foot of building space from year 2000 to year 2010.
The county already has solar panels on its motor pool building and its parking ramp. Repainting the garage white and using solar panels has reduced the ramp’s lighting bill from $960 per month to $200, Mancuso said.
This spring the county will add a “green roof” to the motor pool building, adding three inches of soil and alpine plants. In addition to reducing storm runoff, the greenery extends the life of the roof to 60 years, whereas standard rubberized roofs have a lifespan of 10-15 years due to weathering by sunlight, Mancuso said.
The county annex building in Hibbing uses a solar water heater for its public restrooms, photovoltaic panels on the roof, and a perforated solar wall to keep fresh air circulating.