1 Mar 2015 21:32 (GMT+1)
‘Health check’ for offshore wind turbines
New blade inspection techniques will save energy producers time and money
Identifying and repairing blade failures at offshore wind farms is a challenging, time-consuming and often expensive business, especially when the faulty turbines are in remote or deep water locations.
Blade damage or failure is one of the biggest concerns for the wind energy industry. A recent study by renewable energy underwriter GCube revealed that the industry spends millions of dollars/pounds each year repairing turbine blades at sites around the world.
An estimated 700,000 blades are in operation in 85 countries and current estimates indicate that failures or breakdowns occur in about 3,800 of them – roughly one in 180 or one incident for every 60 turbines producing electricity from wind power.
Blades are obviously an integral part of every wind turbine and this is reflected in their design. Built using lightweight composite materials, and chosen for their strength and stiffness to weight ratio, resistance to corrosion and insulation properties, turbine blades have been developed specifically to provide a reliable and enhanced performance in all weather and offshore conditions. However, an expansion into remote offshore locations coupled with increasing pressure to produce cost-efficient energy appears to be impacting on the blades’ overall integrity and performance.
Given that the repair bill and loss of production for a single blade failure can easily cost $100,000, and often far more, there is a clear industry imperative to categorise blade incidents and to mitigate associated losses as far as possible. Certainly all energy companies involved are eager to cut back on unscheduled production downtime and reduce the frequency and severity of turbine failure.
Now an independent wind farm asset manager has developed a new camera-based turbine blade inspection service which will enable developers, investors and utility companies to rapidly assess and monitor the condition of equipment. The launch of this service, by Paris-based Greensolver, marks an important milestone in the evolution of the operations and maintenance market and, more importantly, for the first time gives owners and operators a credible way to assess and manage the long-term condition of wind turbine blades.
This innovative blade monitoring system is a collaborative design involving Greensolver and another French company, Cornis, a specialist in blade inspection solutions. Based on high-resolution photography, the new blade inspection technique enables operators to assess the condition of at least three offshore turbines each day. The system provides an “almost immediate health statement on 100 per cent of the blade service” and, because images can be compared over time on a web portal, it allows long-term monitoring of each blade’s condition.
Multiple photographic images are taken and combined to create a full picture of the blade surface. An inspection interface allows users to browse over the entire surface to identify any suspicious marks or zones, impacts, cracks or other signs of damage or ageing. Comparing pictures with previous images makes monitoring and tracking defect evolution much easier.
Developers say the inspection technology is a vast improvement on the speed and accuracy of current labour-intensive blade inspection processes – and provides a robust and comprehensive analysis of the blades’ short and long-term performance.
This bespoke analysis capitalises on a combination of high quality photographic imagery and the power of data processing and image enhancing techniques. The technology reduces the need for multi-person inspection teams, additional equipment and keeps turbine downtime to a minimum – saving owners time, effort and money.
“In maintenance terms, wind turbine blades are often referred to as the new gearbox,” says Stephen Bolton, general manager at Greensolver UK. “Traditional blade inspection services that include rope access, mobile elevated working platforms, ground scope and the use of drones and helicopters are expensive, inefficient and arguably pose an unnecessary health and safety risk. This, combined with the experience and feedback from our client base, led us to a partnership with Cornis blade inspection.”