A Growing Industry with a Growing Problem
The rapidly increasing size, efficiency and number of wind turbines is fast making wind a viable alternative to traditional methods of power generation. Only this month, a new record was set for power generated by wind in a single day across Europe. In fact, by 2020, Wind Power is anticipated to become the largest source of renewable energy in Europe, overtaking Hydropower in the process.
LEADING EDGE DAMAGE
The Problem
The ever-increasing size of turbine blades naturally leads to increased tip speeds, often in the region of 180 mph for some of the largest turbines in service. The tip velocity and environmental conditions lead to significant erosion and damage of the leading edge. The effects of which can emerge in as little as 2 years’ service.
As wind turbines can reasonably be expected to operate continuously for 15 years, this is a significant problem for turbine Operators. In lieu of replacement, maintenance and in-situ repairs of the blades are the best method for countering the deterioration because they are significantly cheaper. Studies indicate that a blade repair can cost just 10% of total cost of a replacement blade and when coupled with the significant downtime associated with replacement, this makes repair and maintenance increasingly economical.
REPAIR METHODS
A key factor in repairing the leading edge is preserving the original profile of the blade, so that the aerodynamic performance can be maintained. These include:
Elastomeric tapes:
These exhibit good erosion performance yet present difficulties with application, especially in-situ. Tapes require the blade to be re-built to its original state before application of primers then the tape itself. It can also be difficult to apply a long strip seamlessly. A small loss in adhesion of the tape could lead to dis-bondment along the entire length of the blade. The implications of this are not only a full re-coat along the entire blade but it could also damage the turbine.
Gel coats:
These coatings are generally easier to apply than tapes; however, they do not display the same erosion performance. The use of gel coatings will generally require several coats and the use of primers, in addition to this they can be very sensitive to moisture and temperature, therefore narrowing the application window.
Belzona Solutions for Leading Edge Protection:
Belzona have a range of polymeric materials specifically designed for rebuilding surfaces and providing erosion protection, including cooling tower blades, since the 1990’s. These materials have a proven history in erosive environments and the wind industry. For more information on how these systems can be used, view our recent post on How to Create a Leading Edge Protection (LEP) with Belzona.
5 Reasons for choosing Belzona
1. Performance
As mentioned previously, Belzona materials have been used extensively in challenging areas, showing excellent performance in a variety of erosive environments. They also have proven experience within the Wind industry.
Belzona 1341 was patented for use on Mitsubishi turbine blades over 10 years ago; many of those turbines are now being decommissioned with the Belzona still intact, having provided protection throughout its service. Belzona coatings for the leading edge have also been extensively tested to international standards, including ASTM G73 ‘rain erosion test’ and ASTM G76 ‘solid particle impingement test’.
2. Ease of Application
Belzona materials are designed for ease of application. Both coatings and rebuild solutions can easily be applied by hand, without the need for specialist tools. A simple two-coat system allows repairs to be easily conducted in-situ as well as OEM.
An additional benefit is a wide-application window. Belzona materials are solvent-free and cold curing with no shrinkage. Belzona leading edge coatings will also cure down to 5⁰C without the requirement for external heat, allowing for year-round maintenance. In the event of adverse weather conditions, it is unlikely that Belzona materials will need re-applying.
3. Excellent Adhesion
Belzona materials demonstrate excellent adhesion to a variety of GFRP substrates, without the need for primers or a multi-layered application. Unlike other methods, the blade only needs sanding to remove the surface gloss and create a rough profile, as they have a good chemical bond with the substrate.
If the profile requires re-building, then a Belzona paste-grade system may be used to easily re-create the original profile. If applied within the overcoat window, then the paste grade will not need any preparation before application of the Belzona coating.
4. Ease of Inspection
Belzona coatings come in two colours which are designed to strongly contrast with each other, which aids in application as it is simple to visually inspect that there is full coverage of each coat. This also allows for easy inspection from the ground with just a pair of binoculars. Should patch repairs be necessary then these are just a simple to apply and will not require a full re-coat.
5. Return to Service
Return to service is extremely important for Operators, as a turbine out-of-service is lost revenue until it is back online. Belzona coatings provide a fast return to service without the need for external heaters or UV lamps, reducing overall cost and complexity of the repair.
Continued Improvement
Belzona is always striving to advance and improve their range of solutions for industry, the Wind sector is no different. Considerable R&D efforts are being made to not only improve our current solutions but also expand the range and provide ever better performance.
