MidAmerican Energy is inspecting Vestas wind turbine blades equipped “with a certain lightning protection system” following a blade failure at its Beaver Creek wind farm in Iowa.
The utility said that a blade broke last week on a Vestas V110-2.0 MW unit at the 170MW, 85-unit project and that it has “isolated the issue to Vestas blades with a certain lightning protection system … that have also been in proximity to lightning storms of a certain magnitude”.
As a result, MidAmerican has idled 46 Vestas turbines across its 3000-turbine wind power fleet while inspections are carried out.
The blades of the 46 units will be inspected for damage and will be repaired or replaced as necessary, MidAmerican added.
“Though a blade failure remains an extremely rare occurrence, even one incident is not acceptable,” it said.
“Safety is our top priority and we are working with Vestas to ensure that all of its blades within MidAmerican’s wind fleet are safe.”
MidAmerican reconciled weather data and wind turbine monitoring data to identify all of the potentially affected blades.
Vestas confirmed that it has started a root cause analysis (RCA) into the Beaver Creek blade failure. It is already undertaking RCA studies at other wind farms where similar failures have occurred in recent months.
In July and September Swedish wind farm developer OX2 reported blade failures on separate V136-4.3MW units at the Valhalla wind farm, while in October a blade fell off a V150-4.2MW unit at the recently-commissioned 336MW Dundonnell wind farm in Victoria, Australia.
In September, the blade of a V150-4.2MW machine at the EDPR-owned 125MW Timber Road 4 wind farm in Ohio, USA, fell off.
In August Vestas reported an extraordinary warranty provision of €175m to conduct upgrades and repairs of blades relating to high intensity lightning.