Sand and ice erodes the rotor blades. Repairs usually take considerable time. But Bladefence has introduced a new, quick method of repairing cracks.
Bladefence uses a resin system that reacts when exposed to UV-light. The process from viscous glue to hardened material can take less than five minutes.
Conventional methods may require up to 24 hours for the epoxy resin to fuse the carbon fiber or fiberglass in the blades.
Normal methods also require an ambient temperature of at least +15 °C and a relative humidity of < 60 % for the initiation of the chemical process in the resin.
”With our method we can operate down to + 5 °C and tolerate 90 % relative humidity, ” says Ville Karkkolainen, managing director of the Finnish company Bladefence.
What does this mean for turbine owners?
”One of the key benefits of rapid repair is reduced turbine downtime. With multi-megawatt turbines, downtime costs can easily run into hundreds of Euros per hour.”
”It also extends the time during which repairs can be carried out from three to six months a year.”
More repairs can be done, in other words…?
”Yes. With a small time window, turbine owners only carry out vital repairs. Less important issues are not addressed. Now they have the time – and the financial resources – to fix even the small cracks.”
But do you really have to fix every minor flaw?
”Even a small crack allows water to penetrate fiberglass and make it wet. In the winter this water freezes and expands inside the blade, widening the crack.”
What causes cracks?
”Some blades cope better than others. But the most important factors are location and local conditions.”
”A steel mill or coal power plant nearby has a huge effect on the blades. Ice is another problem. I’ve seen the top coat of a blade worn down in a year from small airborne particles hitting the blade surface.”
”We also have problems with chunks of ice coming off the nacelle or one rotor blade and hitting other blades.”
Blade problems haven’t been discussed as much as faulty gear boxes – is this changing?
”In recent years it has become clear that not only gearboxes but also wind turbine blades require regular, high quality maintenance. I think we are moving towards a common best practice in the market where blades are maintained annually and not just when it’s absolutely necessary.”
Facts:
Ville Karkkolainen is the managing director of Bladefence, an independent Finnish service provider specializing in wind turbine blade inspection, maintenance and repair. The company was established in 2010, has twelve employees and is looking to hire another ten.