GE sees 20% blade retrofit boost

US wind power major GE has demonstrated a ground-breaking blade extension technology that has been shown to boost energy production from two of its 1.5MW turbines by 20%.

The retrofit concept, which involved sawing a 37-metre-long blade in half and fitting in a seven-metre insert, transformed a pair of GE 1.5-77 prototypes at Noble Environmental Power’s Clinton project in New York state into 91-metre-diameter machines, expanding each turbine’s swept area by 40%.

“The blade extension program for GE is a great example of the magnitude of technology advancements GE is capable of developing,” says GE renewable energy engineering team leader Mark Johnson.

“Achieving production gains of more than 20% for existing units is a challenging task, and with GE’s expertise in engineering aerodynamics, material science, structural engineering and controls, we continue to be able to help our customers operate more profitably and efficiently.”

The ten-month trial of the extended blades, made possible by incorporating improved methodologies and advanced controls for load mitigation, takes the technology “beyond IEC requirements”, says GE, based on static strength and fatigue tests totalling more than six million cycles.

“The extended blade programme will provide a solution for all the turbines — from every manufacturer in the installed base — that have been performing below expectations,” says Keith Longtin, GE’s wind product-line general manager.

“Segmentation, if it offers lifecycle savings, has to be right,” he continues. “For land-based turbines the only way you are going to get rotor diameters of 140-metres and more cost-effectively is with a segmented blade."

GE first explored the concept of blade extension over five years ago at The Netherlands’ ECN testing facility with trials of a 2.5MW machine outfitted with extended versions of the company’s 48.7-metre blades.

Throughout the development of the extensions for the Clinton wind farm prototypes, purpose-designed for Noble’s low-wind site, the GE team filed some 16 patent applications and developed custom tooling for the insert installation.