FAIRBANKS — If you fly or drive to Anchorage, you might catch sight of the giant white towers of the Eva Creek wind project, which are expected to be putting power into the GVEA system by October, the electric utility says.
The scale of this $93 million project, the largest wind farm in Alaska, is best shown in photos and statistics. The towers and blades are in place, with testing set to start next month.
Each of the three blades on a tower is 147 feet long. From the base of the tower to the tip of a blade when it is vertical, the turbines are 410 feet high.
The seven-ton blades are made of fiberglass and balsa wood, which creates a favorable strength-to-weight ratio. At peak production, the blades will rotate about 15 times per minute, with the outer tips hitting 150 mph.
The hubs around which the blades move are about 240 feet above ground, which is about two-and-a-half times higher than the Northward Building.
The towers are easily visible now on the breezy ridgetops by passengers on jet flights to and from Anchorage. The wind doesn’t always blow, but it is expected that the machines will be putting out maximum power about 36 percent to 40 percent of the time, GVEA says. The wind is more reliable in the winter than summer and the maximum energy output is 24.6 megawatts.
Michels Wind Energy of Wisconsin is the general contractor, while the major local subcontractors are Brice Inc., which is doing the roadwork and the foundations; Fairbanks Sand & Gravel, which is doing the concrete; Redi Electric, which is doing the wiring; PDC Engineers, which did much of the infrastructure design for the road, foundations, etc.; Ghemm Co., which is constructing two buildings on the site; and Carlile, which was hired by Brice to haul equipment to the site. Brice got the contract for the groundwork a year ago, so this has been a rapid project with tight deadlines.
During the peak of the construction this summer, 160 workers, on two shfts, were working six days per week.
Each foundation contains enough concrete to build more than a mile of a city sidewalk, about 480 cubic yards. The foundations each weigh close to 1.4 million pounds.
The towers are attached to the foundations with 144 bolts, 72 on the inside and 72 on the outside. The 1.5-inch bolts are embedded 10 feet into the foundation.
The towers have three sections that were bolted together on the site and lifted into place by a crane that had to be shipped on the railroad and assembled from 23 pieces.
The optimal wind speed for producing power from the REpower NM92 turbines is 24 mph, though the towers will start working at 12 mph, which is a good kite-flying speed. When the winds hit 54 mph, the turbines are designed to shut down.
The turbines are designed to produce about as much power as is generated from the downtown coal-fired power plant owned by Usibelli.
But it is expensive power.
The $93 million project was funded by a $13.4 million grant and an $80 million loan at less than 2 percent interest.
While these towers are among the tallest ever constructed in Alaska, they are not the tallest. For instance, the LORAN navigation stations had taller towers.
At the other big wind project under construction in Alaska, at Fire Island near Anchorage, the towers are somewhat smaller than the Eva Creek models.
Dermot Cole can be reached at firstname.lastname@example.org or 459-7530.