ELKTON – A costly repair process is nearing completion at the 67-turbine Grand Meadow wind project owned by Xcel Energy.
“For this time, it’s more unusual,” said Nathan Svoboda, Grand Meadow’s plant manager, of the ongoing repairs at the relatively new wind project. “We’re seeing some steel quality issues in the gearboxes that we have. They’re just not holding up as long as they should.”
Of the 67 General Electric 1.5 megawatt turbines near Dexter, 21 had functioning gearboxes during a routine 2010 inspection, according to a 2011 filing made with the Minnesota Public Utilities Commission. The other 46 were classified as follows:
• 32 were dubbed “unusual/monitor.”
• 12 were noted “abnormal/repair expected eventually.”
• Two were called “abnormal/repair required.”
The PUC filing says Xcel’s budget assumes two gearboxes will need replacing on an annual basis at an estimated cost of $250,000 apiece. Wind projects have a typical lifespan of 20-30 years, if not longer.
Outland Energy Services battled through early-morning fog Wednesday to remove the rotor, three blades and the hub in order to replace the gearbox on Turbine No. 161, a few miles south of Interstate 90.
The Minneapolis company used a 310-foot crane, which was transported piecemeal from Minneapolis via numerous semi trucks, in order to repair the 250-foot turbine. Svoboda said it typically takes two days to erect the crane, about two days to replace the gearbox, then one to two days to disassemble the crane.
Svoboda declined to say how much Xcel Energy has paid to replace the three gearboxes this month, but the previously mentioned PUC filing suggests some financial hardship related to the Grand Meadow project. In addition to the gearbox issues, Xcel installed a central greasing system in summer 2011 to prevent generator failure. Despite that measure, the first generator was expected to fail this year – and every third year thereafter – with repair costs estimated at $360,000 apiece.
Additionally, Svoboda reported an “extraordinary event” to PUC in January, when an on-site cable failure took out 16 turbines that were generating 24 MW of power.
Unpredictable fall weather has made recent repairs tricky. Jon Carell, lead technician at the Grand Meadow wind project, said that wind speeds dictate when work can be done. Two workers spent much of the foggy Wednesday morning in a lift bucket hundreds of feet in the air. It was initially planned for overnight Tuesday – using huge spotlights – but a mechanical failure delayed.
While the gearbox replacement schedule remains uncertain moving forward, Xcel already has plans in place to address the ongoing concern. Outland signed a contract with Xcel in May, agreeing to “provide operations and maintenance services at three Xcel Energy wind farms totaling 328 MW until 2017,” according to a press release. Xcel owns the Grand Meadow and Nobles wind projects in Minnesota, along with a 26.5 MW project in Colorado.