December 1, 2008

The return of the Clipper Liberty wind turbine

Drew Robb

Crane convention

To remove the drivetrain on the Clipper turbine, the blade rotor must first be removed, so it made sense to make the gearbox and blade repairs simultaneously. The plan was to ship a new and final-inspected drivetrain to the site, remove the rotor, and begin reinforcing the blades on the ground while mounting the replacement drivetrain on the tower. Once the rotor blades were reinforced, the rotor would be reattached and the turbine recommissioned. The defective high-speed pinions were replaced as part of the drivetrain remediation process.

Bringing down eight sets of rotors and gearboxes, and replacing them on-site also proved to be quite an undertaking. Four cranes were required at Steel Winds: one crane dropped the rotors, one replaced the gearboxes, a third reinstalled the rotors, and the fourth performed other various activities.

"The crane usage is one of the more costly elements," said Maurer. "We organized shifts so we could have staff installing rotors 24 hours a day in order to obtain the best efficiencies with our crane operations."

As well as Clipper technicians, QC experts from Europe, Occupational Safety and Health Administration safety staff, independent engineers representing customers, crane operators, training staff, and many others were present at the Lackawanna facility.

By all indications, this wind turbine remediation project will be no more than a hiccup in Clipper’s long-term goal to compete with the established wind turbine manufacturers. Clipper finished work at Steel Winds in May. From June 1 through the end of September, the plant’s availability rating was 96%.

Moving on

Having produced some 400 turbines to date, Clipper is targeting another 300-plus wind turbines by year-end 2009 and will expand production further the following year. According to Maurer, the company currently has sufficient plant capacity and equipment, a trained workforce, and processes in place to assemble more than 500 Liberty turbines annually, with potential for further capacity extensions (Figure 3).

3. Gearboxes good to go. Upgraded gearboxes under assembly at the Clipper Windpower Cedar Rapids wind turbine manufacturing facility. Courtesy: Clipper Windpower

Sales of the Liberty hardly skipped a beat. The company sold 370 2.5-MW turbines in 2006 and 825 units in 2007. Most of last year’s orders were from existing customers, such as First Wind, and were confirmed once the RCA was completed. Furthermore, the company has announced an additional 1,500 units (3,750 MW) in joint development and contingent sale agreements.

Encountering problems with a new design, produced in a new manufacturing plant while key vendors are ramping up their production, is not unusual. What is unusual is that Clipper didn’t immediately jump to conclusions about the cause of the failure. Instead, it took time to identify the root cause and then modified its manufacturing processes, and those of its key suppliers, to ensure that the problem never happens again. That is the real definition of quality.

— Drew Robb is a Los Angeles-based writer specializing in engineering and technology issues.