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Down for maintenance

Wind turbine will be non-operational till Nov.

By: Leah Oathout/Production Manager

The sky south of the West building is conspicuously empty. The large wind turbine, identical to the one on the north side of the building, is down for some major maintenance.

“[The turbine] was making noise for a long time,” explained Scott Rawlings, Assistant Director of Physical Plant Operations. “It took a long time to discover the bad bearing.”

The main bearing that allows for movement of the blades has been declared non-functional. Through extensive study by Rawlings and other LLC staff on the project along with the manufacturer, BORA, it was determined that the bearing was either damaged on the trip to LLC or had manufacturing flaws that caused it to fail over the summer.

“BORA and Lake Land agreed that the bearing needs to go,” Joseph Tillman, Renewable Energy Instructor and Coordinator, said.

Tillman expects it will be early November before the turbine will be functional again. The bearings used in the turbines are only made in one place; South Africa. It will take three months to build and ship, depending on how quickly the bearing can clear United States customs.

turbine2-clr

The main bearing that allows the blades to spin is forty inches in diameter and six inches thick.
Photo by Leah Oathout

Unlike the brake system, which Rawlings repaired in the Spring semester, the main bearing cannot be fixed. Forty inches in diameter and six inches thick, the bearing comes preloaded from the factory and is not adjustable.

As can be expected, this problem is as expensive as it is time-consuming. The bearing itself costs about $15,000 but the rental crane required to lift the seven ton head, called the nacelle, into place is the same price. Thankfully, BORA and the construction management firm CTS, which does the geothermal work on campus, will be paying the bulk of the bill.

“[The replacement] is pretty darn close to free for [LLC],” Tillman said.

While waiting for the bearing, there are many small adjustments that require attention. Rawling explained, “[The repairs are] nickel and dime stuff. It’s just nice to not have a 110 foot climb.”

Until the bearing arrives and is installed, the nacelle of the turbine is staying in a spare West hall garage. This presents green energy students with the opportunity to examine the internal workings of the turbine without having to climb up ten stories.

For those who are unfamiliar with the anatomy of wind turbines, the nacelle contains the gearbox, brake system, and generator, all of which are run by a main shaft that runs through the bearing. The blades bolt to the hub or nose cone which in turn is also bolted to the main bearing. The tower contains the yaw system that allows the nacelle to turn, the power cables, and the service ladder. At the bottom of the tower is the control panel.

Rawlings summed up the nacelle construction much more simply: “The main bearing bolts to the frame. Everything else bolts to the bearing.”

While simplified, this is the best illustration for the importance of the main bearing. Without it in proper working condition, the blades cannot turn and turbine cannot generate electricity. So, while it will take a good amount of time and money, the bearing is well worth the wait.


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