Shortly after a blade came loose at the Ocotillo Express Wind facility in Imperial County earlier this month, facility operator Pattern Energy deftly handed the matter off to turbine builder Siemens Energy. With a muted press statement issued Friday, it looks as though Siemens is now trying to pass the buck as well.
In an email newsletter issued in the afternoon on Friday, May 24, Siemens pointed a finger at a root component of the company's ten-ton, fiberglass-epoxy B53 blade, the model which detached from the turbine at Ocotillo and landed about 150 yards away across a publicly accessible dirt road.
The meat of that email newsletter:
While Siemens has not yet fully concluded its investigation, it is now focusing its efforts on supplied root segments that appear to have separated from the fiberglass laminate of the main blade. Root segments are pre-cast inserts used to construct the blade root and are supplied to Siemens by a number of suppliers. As a result of the thorough analysis conducted so far, Siemens has confirmed that this issue is not related to the design of the blade.
In the wake of the May 16 blade throw incident, Siemens "curtailed" all its turbines worldwide that use the B-53 blade. That's about 700 turbines worldwide, 600 of them in the U.S. "Curtailment" is a term of art meaning that the turbines are slowed, sometimes but not always to a complete stop. Curtailed wind turbines don't produce power, but if the affected blades are still moving, and stresses on the blades' connection to the rotor hub still shifting, the possibility of blade throw isn't completely removed. Ocotillo resident Parke Ewing told ReWire that the blade throw incident on May 16 happened during a period of light wind, and it's doubtful the turbine in question was spinning at anywhere near its peak speed.