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GE identifies cause of blade breaks

General Electric says it has determined that the root cause of blade breaks last month at wind farms in Michigan and New York State was a “spar cap manufacturing anomaly.”

“We’ve identified a discrete set of blades that could have been subject to this anomaly and we are working with potentially affected customers to help ensure the reliability of our wind turbines and their safe operation,” Lindsay Theile, a spokeswoman for GE Power & Water, tells Recharge.

She notes that to date, a small percentage of the potentially affected blades that GE has reviewed are impacted, adding that blades that are not impacted are safe to operate.

“Following the discovery of the manufacturing anomalies, we have put additional controls in place to prevent future events from happening,” Theile says. These include resourcing GE inspectors who are performing additional quality reviews and data verification, as well as oversight from GE Engineering.“The quality and reliability of GE turbines is of utmost importance to us,”she adds.

Spar caps are load carrying structural members usually made of carbon fibre that help support the blade’s outer aerodynamic shell. Carbon fibre allows higher stiffness and lower density to enable a thinner, lighter blade profile.

GE confirms that carbon fibre is used in the affected spar caps. It has been specifying carbon fibre for its 48.7-metre blades used for the 1.6-100 turbine that were affected by the breaks.

The single blade breaks occurred 7 November at the 112MW Echo Wind Park owned by Michigan utility DTE Energy and Invenergy’s 94MW Orangeville Wind Farm in western New York State.

DTE says the Brazilian-manufactured blade broke off during a pre-commissioning test at Echo, which is under construction. The utility suspended work and shut down 59 similar operating units there.

Scott Simons, a DTE spokesman, tells Recharge that all the units remain out of operation as the utility and GE test each blade. Aside from the turbine affected by the incident, 10 other units must also be commissioned. Simons does not expect the turbines to resume operation until sometime in January.

Invenergy on Monday says it has resumed commissioning and operations activity at Orangeville on turbines cleared by GE, one month after a blade broke from one of 58 units there. The unit’s commissioning had begun on 13 November and it was in operation when the mishap occurred. Construction of the wind farm had been completed. GE has not said where the blade was manufactured.

"The investigation of turbine blades at the Orangeville Wind Farm involves a thorough inspection of each individual blade. This process is ongoing, as GE personnel makes its way through the Orangeville fleet, turbine by turbine,” Invenergy says in a statement.

“We have confidence in the safe operation of these turbines. Moving forward, we will continue to resume activity incrementally as each unit is cleared as safe to operate,” it adds.

In March, a GE blade broke from a turbine at DTE's Thumb Wind Park in Michigan. GE found that breakage was caused by an "isolated supplier manufacturing defect."

GE sources blades from a global network of suppliers.

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