OEMs field-testing blade inspection tool

A new device call Notus promises to slash wind farm operation costs by scanning and detecting blade coating and surface faults using terahertz imaging -- a technology developed by US security agencies following the terrorist strikes in New York in September 2001.

Siemens Gamesa is leading the wind turbine OEMs trying Das-Nano's new blade analysis tool
Siemens Gamesa is leading the wind turbine OEMs trying Das-Nano's new blade analysis tool

The Notus prototype is now being used under special pilot agreements by turbine OEM Siemens Gamesa Renewable Energy (SGRE), and utility developer Iberdrola.

"Agreements are being negotiated with Nordex for its upcoming blade monitoring campaign," said Spanish wind power veteran and pioneer Estaban Morrás, chairman co-founder of Spanish start-up Das-Nano, the creator and developer of Notus.

Suzlon and Vestas are also showing interest and, at the time of writing, a robotics multinational had just made a proposal to develop the technology jointly, Morrás added.

Morrás claimed that with Notus, for the first time, "operators can properly tackle the Achilles heel of the wind industry: blade faults through coating defects.

Blade coating thickness and uniformity can be measured precisely with the scanner, while defects in the underlying blade surface, can be detected both in the factory and the field.

Notus offers micra (one thousandth of a millimetre) imaging of the bonds between the different layers within the blade coating.

Destructive testing

To date, adherence testing on blade coatings conventionally involves so-called "pull-off" tests. A metal stub is cemented to the blade surface, then a hydraulic machines pulls on the stub until it pulls part or all the coatings off the blade, including part of the blade surface.

The layers are, typically, the protective paint, the gel-coat, gel-coat finishing, and leading-edge protection.

"Pull-off testing is imprecise and destructive," said Eduardo Azanza, Das-Nano CEO and co-founder. "The blade needs repair after the test and the results vary considerably."

"Typically, pull-off testing is made on just one in ten blades produced and only on selected sections," said Morrás. "Yet blade repair is an extremely common operational cost, involving downtime, crane deployment and staff hours. The costs go off the scale in offshore installations."

With such savings in mind, the Notus is a snip at its current commercial price of below €100,000 per machine, said Morrás.

Das-Nano was founded in 2012. In 2013, US defence advisor Eugene Chudnovsky and Spanish physicist Javier Tejada joined the company to develop Notus under a technology transfer agreement with Germany’s Fraunhofer institute, which, in turn, was further developing terahertz scanning following its first large-scale applications in post-9/11 America.

"Wind technology is usually a pass-me-down from automotive and other sectors but it’s the other way round with Notus," says Morrás. Yet, as regards the first commercial applications, he conceded that the car industry beat wind to it, specifically with the start-up in 2018 of a scanner at the VW factory in Wolfsburg for checking car body coatings.

SGRE's tests with Notus have so-far involved ten blades — both in the field and factory — plus a series of test samples. The company told Windpower Monthy it had validated Notus’ capability in detecting coating uniformity flaws, though validation on adherence is yet to be completed. SGRE is now considering series application of Notus.

Iberdrola has declined to comment on its use of Notus until its two-year blade analysis campaign is finalised end-2019.

"Further uptake is only a matter of time," said Morrás.

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