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Six meteorological (MET) towers installed between Carpio and Berthold are a sign of the most recent progress for Hartland Wind Farm.
“We need more concentrated data,” said Curt Johnson, principal with Denali Energy, the Minnesota-based company developing the Hartland Wind Farm project. “We need an assessment of our power profile and what we’re going to generate for energy.”
Actually, one of the towers has been in place since April 2008, churning out wind speed and direction information on property owned by Glen Johnson in
“The longer we have data from our area, the better the profile is for anyone interested in investing in the project,” said Craig Swenson, another Denali Energy principal. “We’re adding the five towers within our first 500 megawatt area for a more accurate profile.”
He paused and laughed. “Our two original towers reflected data that were so strong, investors are saying, ‘Prove it,’” he said. “We really only have to call any resident out here to ask about the wind, but this gives computer proof.”
Johnson described the competition among wind energy companies operating in different states. “Who’s got the windiest wind?” he said. “On the average, our wind speeds here are significantly higher than most other wind speeds.”
From the data recorded since 2008, wind speeds in Phase I of the proposed Hartland Wind Farm project range from 0 to 60-70 mph, with an average of 21 mph. Direction varies from the northwest to the southeast, with seasonal patterns observed.
Johnson explained that wind energy projects in other states typically experience periods of time with very little wind. “One thing we can confirm is that we have much more wind during the daytime hours, which are peak energy hours, than other places,” he said, adding that electricity generated during those times would be in demand by utility companies.
MET towers combine
safety and technology
The MET towers stand 60 meters, or 197 feet, tall, with instruments to measure wind speed and direction attached at heights of 60 meters, 40 meters, 20 meters and 10 meters. Additional sensors at the 10 meter level measure barometric pressure and temperature, with those data provided to the National Weather Service for correlation.
Jacob Birkeland, field engineer with the EAPC Wind Energy Group in
Birkeland pointed to paired black and white anemometers installed at each of the four levels on a tower still laying close to the ground. “That will give us the direction, correlated with wind speed,” he said. “It’ll tell us how fast the wind is coming, its direction throughout the year, and how those patterns change. We use two models to verify the information.”
Each tower is outfitted with a small box at the base, containing a computer to transmit the recorded data to EAPC offices. Information is generated and sent through a satellite link every 10 minutes. “All the wind data collected from this tower is emailed to several offices to be analyzed,” said Birkeland, listing EAPC and Montgomery Energy (a partner with Denali Energy) as examples.
The towers were erected in planted fields during the last week in July, with cooperation from the landowners and farmers involved. Generally, each tower can be left alone after a successful installation, with data sent remotely. However, a short access trail through the field was necessary at every site for the EAPC crew to drive in and set up the tower.
“Each landowner is compensated for the lease of the land for the MET tower, as well as the farm tenants for any and all crop damage as a result of this,” Swenson said. “There’s been a lot of excitement expressed by the landowners as we’ve met with them, though.”
He added that he and Birkeland talked individually with the landowners and farmers to determine the best location for the tower at each site. “The towers will be up for at least a year,” said Swenson.
According to Birkeland, each tower is held in place by guy wires attached to 12 load anchors extending into the ground and arranged on four sides of the tower. “These leave no trace,” he said. “They’re very easy to work with. There’s a seven foot threaded rod [in the ground] that can be removed when you take down the tower.”
These towers include ice-free sensors. “When you get ice build-up and some sensors do freeze, these will provide back-up and verify the wind data,” Birkeland said.
Each guy wire features several small plastic tags in fluorescent yellow and orange colors, attached as bird diverters. Hartland Wind Farm discussed the use of the diverters with representatives from the U.S. Fish & Wildlife Service, with these particular tags chosen for a trial run.
“There was no information out there about the impact of these towers and guy wires on birds,” Johnson said. “Putting bird diverters on these wires is completely voluntary on our part, but we’re going to have a study done over the next one and a half to two years to provide information to our industry and other industries who use these types of facilities. We’re finding out that the market for these is under-served.”
The top of each tower is outfitted with a solar-powered flashing aviation light as well as a lightning rod. The towers have been painted in broad orange and white stripes to alert crop sprayers, personnel flying from Minot Air Force Base and other pilots in the area. “It’s the same paint type and color scheme towers over 200 feet are required to use,” said Birkeland.
Swenson made a point of discussing the towers’ safety features with crop sprayers working that region. To his surprise, they said they appreciated the bird diverters as a way to make the guy wires more visible.
After several hours of preparation, Birkeland’s four-man crew raised each tower in about half an hour, using a quiet winch to pull the tower from a prone to upright position. The group stopped periodically to check their progress and tighten slack noticed along the wires on any of the four sides. Birkeland stood along the winch side to eye the set-up and call out instructions. “I’ve put up over 200 of these things,” he said between comments to his crew members.
Swenson was looking forward to seeing data recorded by the new array of MET towers. “These data remove doubt about the viability of the project,” he said. “Our initial data showed a strong wind profile, and investors have been skeptical about that.”
He agreed that with $5.4 billion expected to be spent on the first 500 megawatt phase of the project, investors had a right to demand accurate information. “They’re looking for an efficiency factor,” he said.
The eventual size projected for the wind farm project is 2000 megawatts, with turbines placed in Ward, Burke and Mountrail counties.
The more complete wind profile developed by data from these six MET towers will also provide key information needed to choose turbines for the sites. “This will help us in matching the right tower to the right location,” said Swenson. “It will help us determine the turbine size and blade length needed.”
Other work for the Hartland Wind Farm project during the summer included studies conducted for the Habitat Conservation Plan required by the U.S. Fish & Wildlife Service and verification of survey marker coordinates for potential turbine sites.
Anyone with further questions about the MET towers or Hartland Wind Farm is welcome to contact Swenson by calling 1-877-557-1031 or by email at firstname.lastname@example.org.