Why are the wind turbines off? 

Last weekend when traveling to San Diego and again on the way home, we noticed that the wind turbines were idle. There was a high wind alert issued, so why would a source of natural power be unused? – Traveler, Yuma

This question came from a Yuma resident who probably was not familiar with the nearly two-month shutdown of the Pattern Energy Ocotillo Express wind project.

Sometime today the first of the 112 turbines affected by the closure could begin spinning again, provided there is wind to make it go.

On May 16 a blade from one of the turbines somehow broke off and plummeted to the ground, effectively closing the entire project until officials with Pattern, the turbines’ manufacturer and the Bureau of Land Management could be certain the safety concerns had been adequately addressed.

Actually, Pattern sent us a statement Monday that was very detailed as to what happened with the falling blade. Before Monday there had been some question as to whether B53 blades produced by Siemens were a problem themselves, as reports of falling blades of the same make and model had occurred in other places.

However, according to the statement from Pattern, after Siemens studied the B53 blades the problem was confined to the bonding of some parts at the base of the blade.

“The analysis revealed that the root cause is not related to the design of the blade. The Siemens fleet of wind turbines has an excellent safety record and this type of blade failure is extremely unusual. Siemens has manufactured over 25,000 turbine blades using this root design and the two recent incidents in Iowa and at Ocotillo Wind are the first time a failure of this nature has occurred.

“Siemens concluded that the fracture happened as a result of insufficient bonding at the root end 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. These ‘root segments’ are bonded to a fiberglass layer as part of the blade manufacturing process. The insufficient bonding was caused by improper surface preparation of the root segments. As of June 25, all Siemens wind turbines with B53 blades globally have been inspected and a small number of blades will be replaced because indications of insufficient bonding were discovered,” according to a statement from Pattern.

As a precaution, Siemens will also apply a minor update to all existing B53 blades, including at Ocotillo Wind. “This upgrade will provide an extra level of protection by enhancing the bond between the pre-cast ‘root segments’ and the fiberglass layer,” according to the release.

Seven blades at Ocotillo Express will be replaced.

It’s interesting that we would receive this Probe question. Even before the shutdown, there seemed to be some question as to whether there is ample wind in Ocotillo to power the project. Critics have said no, while Pattern says yes. That is the subject of a story in this coming Sunday’s newspaper.