How to save on blade repairs
September 14, 2018
Collecting data on the frequency and type of blade wear-and-tear can save wind farm owners time and money.
Wind turbine blades are impressive engineering feats that push the limits on what has been accomplished in the capture of energy. Wind engineers strive to create blades within restrictive design requirements that seek to optimize energy production through a mix of low weight, high strength, extreme flexibility, and durable exteriors. At the outermost tip of a 100 meter rotor a rain drop can hit the blade at over 280 km/h, not to mention dust, dirt, snow, ice or any other inflow particles. This is an incredible force that challenges the integrity of the surface coating of the blades as they spin, day in and day out, through all seasons.
As the industry continues to find efficiencies and lower the cost of electricity, customizable solutions for blade wear-and-tear are increasing from the factory through to aftermarket add-ons. Since no two climates are the same, customizing the protection of the leading edge of blades is becoming a highly scientific exercise. It’s important to ensure that additional costs are avoided for mild climates and blade longevity isn’t compromised in harsh environments. The industry is therefore presented with two questions:
- What are the actual environmental conditions that my current or future turbine blades will experience?
- How can I tailor my turbine blades to require minimal maintenance and have the longest life span?
Data has become the focal point for answering both of these questions.
The first question is answered with the analysis of existing wind farm conditions or data available to developers prior to turbine installation.
The second question is addressed by taking that analysis and holding it up against the aftermarket solutions being offered to find the lowest cost option that will stand up to the observed or anticipated wear-and-tear.
The better the analysis, the more finely the solution can be tuned, saving wind farm owners money on operations and maintenance. By refining the solution applied, owners can prevent overspending on a product that might be more heavy duty than necessary while avoiding a solution that is unable to endure the specific site conditions resulting in more frequent repairs.
Here is a non-exhaustive list of some mainstream and some more experimental methods for data collection and analysis on blade condition and inflow conditions:
- Ground inspection using high definition photography or telescopes. Images are reviewed by an expert or passed through a defect recognition program to identify areas for repair.
- Drone inspection using high definition videography/photography.
- Fiber optic, strain gauge or piezoelectric vibration sensors installed in the blades monitoring blade vibration signatures.
- Ultrasonic inspection from rope access technicians.
- Thermal and LIDAR (laser) inspection from drone mounted sensors.
- Data analytics detecting underperformance and separating out blade erosion effects.
An important step in collecting all this data is using it to go beyond repair schedules and applying it to predictive maintenance for a specific wind farm location. Frequency of wear-and-tear, the specific type of damage, and other subtleties provide historical information unique to the site and local conditions. These insights also aid in the procurement of protection solutions.
Here are some solutions for blade protection that are currently being offered by the industry:
- Paint: A protective coating is applied to the leading-edge of the blade that takes the bulk of the erosion damage. The surface must be prepared and application typically requires specific environmental conditions to adhere correctly.
- Tape: Taken from the aerospace industry, extremely durable leading-edge tapes have proven effective in various applications. As with paint, the application is key.
- Films or Coatings: Slightly different than a paint, these “paint on” coatings have a thicker application using various materials for hardness, flexibility or other requirements.
- Cap: A molded cap can be applied instead of paint or tape providing a thicker application and a more controlled shape.
Some blade manufacturers are providing these types of applications directly from the factory, increasing the ability to control the environmental conditions for application and quality control.
With the international investment in wind pushing past $107 billion in 2017, solution providers for blade condition analytics and hardware are putting significant effort into offering cost savings and durability to a rapidly advancing industry. This is excellent news for wind farm developers, operators, investors, and electricity consumers as the cost of wind energy continues to fall providing even easier access to emission free electricity.