Wind turbine cleaning: methods, when to do it and how to buy it

Wind turbine cleaning is the set of works that restore the outer surface of the machine: blades, hub, tower and nacelle. No standard requires it at a fixed interval, which is why it is one of the most deferred tasks in wind O&M. This page explains what gets dirty, which methods exist, when cleaning makes sense and what to demand from whoever does it.

What gets dirty on a wind turbine, and why

The tower collects oil and grease streaks running down from the nacelle, dust bonded by rain and, in farmland, residues from crop treatments. It is the part everyone sees from the access track and the reason behind most orders: a tower with black streaks is the first thing an audit or a site visit points at.

The nacelle gathers grease and oil from seals and hydraulic systems, plus ambient dirt. Its housing is the surface closest to the mechanical components.

The blades accumulate insects, dust, pollen, resin and, near the coast, salt. Soiling concentrates on the leading edge, the part that cuts the air first. Blades are also where cleaning is most often confused with repair: a blade with leading-edge erosion is not fixed by washing it.

The methods, compared

There are three ways to reach the surface of a wind turbine: send a person up, bring a machine close, or fly a drone. Each has its place.

Rope access

The traditional method, and still valid. A certified technician climbs to the nacelle and abseils down the blade or the tower, cleaning section by section. It allows contact work, so it is the method when, besides cleaning, something has to be repaired, sealed or checked by hand. In exchange it takes four or five days per machine, keeps the turbine stopped all that time and puts a person tens of metres above the ground.

Platforms, cranes and robots

Aerial platforms and cranes with a basket reach the tower at sites with good access and firm ground, but not the blades or the nacelle of a modern machine. Blade-climbing robots exist and work; their deployment requires rigging on every machine and a logistics effort that only pays off in large, concentrated campaigns.

Drone from the ground

An industrial drone with a pressure-washing system, fed by hose from the crew on the ground, cleans blades, tower and nacelle with nobody climbing. One working day per turbine, 0 people at height, and the crew travels with everything it needs. It requires an aviation permit, a weather window and the turbine in maintenance position. It does no contact work: it is exterior cleaning and visual inspection. It is the method Eolinet works with, and the full comparison with rope access is here, including where the drone does not win.

When it is worth cleaning a wind turbine

Nobody cleans to a calendar, and anyone who gives you a fixed number of cleanings per year has nowhere to get it from. What actually triggers a cleaning is a specific situation:

• An oil leak that has left streaks on the tower or the nacelle: cleaning is part of the repair, because you need to see where it comes from and confirm it has been fixed.
• Before a repair or a repaint of a blade or the tower: no repair is done on a dirty surface.
• Before an audit, an end-of-warranty inspection or the sale of the wind farm: the visual condition of the machines gets looked at, and photographed.
• When closing the annual blade inspection: a visual check of blades and lightning protection is standard practice, and cleaning can be done in the same visit.
• When the image of the site matters: wind farms visible from roads or towns, or with institutional visits.

What to ask a wind turbine cleaning contractor

Whatever the method, there are things you should demand before placing an order:

• That they are prequalified as a contractor by your company, or willing to go through the process: health and safety, insurance, coordination of activities and documentation for every operator or pilot. What a utility asks for is explained here.
• A price per turbine and per scope (full, blades and hub, tower, nacelle), with mobilisation made clear.
• Before-and-after photographic evidence of every machine, not of the campaign in general.
• That they tell you what their method does not do. A contractor who promises to leave the blade as new has not seen many blades: what remains after cleaning is bonded grime, and removing all of it is not possible.
• The real lead time from order, permits included. With a drone it is about three weeks; with ropes, however long the contractor takes to free up a team.

What Eolinet does

We clean and inspect complete wind turbines with drones flown from the ground, at wind farms across Spain, with licensed pilots, aviation permits and public liability insurance handled by us. Minimum order of 4 turbines per campaign and nacelles up to 100 metres. If your case needs contact work, we tell you so and recommend rope access. The scopes and terms are on the services page; with the number of machines, the location and the rotor diameter we return a fixed quote.