December 1, 2008

The return of the Clipper Liberty wind turbine

Drew Robb

The Steel Winds project in Lackawanna, New York, was selected as a POWER 2007 Top Plant because of its unusual location (a former steel mill and Superfund site) and because it was the first commercial deployment of the Clipper Windpower 2.5-MW turbine. That report was written just as the project entered commercial service but before a major gearbox problem was identified. For many new designs, it isn’t a question of if problems will occur but of how the manufacturer responds when problems inevitably do occur. For its handling of Liberty’s problem, Clipper Windpower gets an "A."

What would you expect to find in the first year of any new high-technology, commercial-scale product release? From a new model car to a computer operating system, or perhaps a gas or steam turbine, history has taught us to expect at least a few teething troubles. And so it goes that most every class of industrial or commercial product seems to require an initial phase of debugging before it achieves dependable levels of performance and efficiency.

Original equipment manufacturers can invest thousands of hours in design and prototyping in an attempt to eliminate bugs, but perfection is an elusive goal. It is not usual in this business to spend a year or two — sometimes longer — of field experience refining the operation of new machines. The early experiences of F-class gas turbines is one example.

Growing pains

The same design cycle applies to the wind power industry. In late 2006, for example, Clipper Windpower’s first eight commercial 2.5-MW Liberty turbines rolled off the assembly line at the company’s new Cedar Rapids, Iowa, manufacturing facility. Installed during one of the coldest winters on record in New York, the turbines were placed into service in the first quarter of 2007 on the U.S. banks of Lake Erie in Lackawanna, near Buffalo. The project was known as Steel Winds and was recognized as a POWER Top Plant last year (Figure 1). (See the December 2007 issue for a complete description of the project.)

1. Rust Belt goes green. The Steel Winds Project, the first commercial deployment of theClipper Windpower 2.5-MW turbine, is located on the site of a former Bethlehem Steel mill and Superfund site along Lake Erie in Lackawanna, south of Buffalo. The 1,600-acre site is under redevelopment for public use. Courtesy: Clipper Windpower

Erected on a former Bethlehem Steel industrial site, the eight 2.5-MW Clipper Liberty wind turbines are owned by First Wind (formerly known as UPC Wind), a company that operates 92 MW of energy capacity through three wind farms.

For the first several months, all ran smoothly. Then an on-site engineer at Steel Winds heard an unfamiliar noise in the drivetrain. An inspection and analysis revealed a supplier-related drivetrain timing issue that had caused some gear teeth in one turbine’s secondary stage to break.

After a quick assessment of Clipper’s small but growing fleet, the company decided to test all drivetrains fleetwide. While it was addressing this issue, it looked more closely at its turbines to verify that everything in the field was running as expected. That uncovered a minor problem with an adhesive joint on the blade’s aft shear web, which Clipper elected to address on all its turbines.

Work had to be conducted during the depth of winter with temperatures well below zero.

"We decided to conduct blade repair in winter in order to get the turbines up and running rapidly for the customer," said Jeff Maurer, vice president of Fleet Services at Clipper Windpower, a wind industry veteran who has commissioned more than 1,000 turbines and overseen fleet operations at more than 3,000 wind turbines for GE Wind Energy. "Although it was extremely difficult, we pulled it off and now have the Steel Winds site fully operational."

Result: All eight of the turbines at Steel Winds were quickly returned to service.

Because First Wind has filed a prospectus with the Securities and Exchange Commission (SEC), its representatives could not be quoted in this story. "We address the issue of Clipper’s turbines in our prospectus with the SEC," said John Lamontagne, a spokesperson for First Wind.

According to the prospectus, between May 17, 2008, and August 31, 2008, the cumulative performance of the turbines at Steel Winds met the availability warranty rates agreed to by Clipper. "We anticipate this project will have an approximate 31% to 33% net capacity factor over the next 24 years," says the prospectus. "Assuming a 32% net capacity factor, the average annual electrical production is projected to be 56 GWH."