While constructing Clemson University's $110-million wind-energy test center in North Charleston, S.C., the project owner and its builders were often working toward a "moving target." From the start of construction in July 2011 through completion in 2014, the first-of-its-kind facility's design changed several times, says Jim Tuten, project director with the Clemson University Restoration Institute (CURI), the project owner.
Back in 2011, "we didn't have a clear set of specs," says Tuten, who served as project manager. And while a poorly defined scope can be a project killer, for the team building the SCE&G Energy Innovation Center (as it's now called), this early lack of definition sharpened their commitment to designing and constructing a facility that would function as ideally as possible for its end users. That's because, in reality, Clemson and its builders were fashioning an entirely new type of facility, built largely upon the wishful requests of the wind-turbine manufacturers that were asked to envision an ideal test center.
Located within a decommissioned U.S. Navy warehouse on a rehabilitated brownfield site—chosen for CURI's redevelopment and sustainability mission—the 82,300-sq-ft facility supports the testing of offshore wind turbines by giving manufacturers the capability to simulate an estimated 20 years of field conditions in just a few months. And while other wind-turbine drivetrain test facilities exist, Clemson's LEED Gold-certified center goes several steps further.
The inclusion of a 15-MW hardware-in-the-loop grid simulator, for instance, lets manufacturers evaluate their devices' impact on the grid. By recycling the electricity produced by the drivetrain testing—thus avoiding grid impacts—the center became the world's first facility capable of evaluating 60-Hz equipment, intended for North America, as well as 50-Hz units, designed for global markets.
Despite that early, undefined scope, the construction clock was ticking from the start. A $47-million Dept. of Energy grant, backed by deadline-centric stimulus funds, pushed the project owner and general contractor Choate Construction Co. to get shovels ready.
The project team wasn't completely building blindly, though. Working off early industry feedback, CURI and AEC Engineering began design work by using estimates of the testing-induced forces the building would likely experience, based on factors such as torque capacity and blade loading capabilities. With typical turbine blades measuring as much as 300 ft in length, the facility would have to endure massive, fluctuating vibrations created by the 7.5-MW and 15-MW test rigs, which simulate real-life stresses of offshore conditions.
And even though the site was located next to the Cooper River, atop typically mucky Charleston soil, the builders figured the 39-ft-tall structure could accommodate the giant machines.
But as the facility began moving toward reality, industry's needs—and DOE's suggestions—changed, growing to be "a lot more than anybody had anticipated," Tuten says. Since the test equipment ended up being significantly stouter than expected, one of the first major increases in scope resulted: a redesign of the foundation system.
The site's swampy soils provided a challenge as well. As Tuten told ENR Southeast at the time, "We had heavy loads on muck in a seismic area with flooding potential and high wind loads due to hurricanes on a brownfield site."
Accommodating these greater-than-expected loads and retrofitting the existing structure to current wind and seismic codes required contractors to beef up the foundation by installing 432 steel H-piles, ranging from 46 ft to 57 ft in length.
The research center is built around two massive pieces of equipment, with the smaller of the two driven by a 7.5-MW gearbox, and the other a 15-MW, 341-ton gearbox that is considered to be the world's largest. In addition to being more stout, the foundations—which use friction piles, considered a first for this type of facility—needed to function independently.
"The foundations required isolation from the existing structure such that external vibrations were not induced into the test specimen and test vibrations were not transmitted to the facility," Thomas Lorentz, senior vice president with AEC Engineering, told ENR Southeast during construction.