In order to ensure faster adoption of environment friendly technologies like wind energy, economic competitiveness with traditional, nonrenewable sources of energy is necessary. One important and often overlooked factor that is affecting the commercial viability of wind energy is the high percentage of blade failures. Globally, it is estimated that there are a total of 3,800 blade failures every year.
So, how do we ensure more efficient windmill inspection and maintenance? Are there better alternatives to traditional inspection methodologies? In this blog post, we discuss if drone technology can result in faster and more accurate data acquisition and processing — to result in actionable insights which help mitigate failures and hence, economic loss.
Windmill Blade Defects and the Need for an Optimum Inspection Process
Windmill blades are complex structures that are not immune to manufacturing defects. Delamination defects results in a gap between laminates — which ultimately reduces the bearing capacity. The end result in buckling under external loads. The presence of foreign particles in the building resin, gas bubbles and improperly applied structural adhesive are other reasons why a wind-mill turbine is not able to generate optimal performance. Utilizing an efficient inspection methodology (in terms of time and cost) that is able to accurately pinpoint these defects is critical.
There are several traditional ways of inspecting wind turbines. Using rope climbing teams is one of the most common albeit risky ways of inspection. Another alternative is using ground equipment comprising a high resolution camera, tripod and a powerful laptop for processing data. Both alternatives have considerable drawbacks.
Sending up rope climbing teams is a time consuming, costly and inaccurate way of conducting inspections. Firstly, visually inspecting a windmill is a poor strategy as far as data acquisition is concerned. Secondly, using this inspection method, you can inspect just 2 to 5 turbines every day. Inspection costs could be as high as $1500-$2000 for a single turbine.
What Are the Benefits of Using Drones for Windmill Inspection and Maintenance?
Before we start talking about using drone technology for windmill inspections — let’s set one thing straight. Drone-powered inspections are still in infancy. The challenges are on two fronts — data acquisition and data processing. Even if we are able to acquire voluminous inspection data using drones, it is not possible to process this data — and draw actionable insights without the use of a proper application or software. Having said that, let us look at some of the advantages of using drones for windmill inspections.
Using automation and drones, you can potentially inspect 20 turbines every day. And a faster inspection process and lesser human intervention means that you can bring down your cost to $300-$500 for a single turbine.
It is also critical that you equip your drone with a sophisticated thermal sensor. Using the latest thermal sensors, we can now inspect 15 cm deep into a wind turbine blade. Another advantage of using drone technology is that you can view the feed, real time on the ground station. Moreover, using a drone, you can take complete turbine measurements. You can easily come back a year later, acquire images and video and check if the defect has gotten worse over time.
Can You Use a Commercial Drone like the Mavic or Phantom for Windmill Inspection and Maintenance?
Technological advancements means that now we have more powerful drones and thermal sensors at our disposal. Broadly speaking, three main factors dictate your drone selection for wind turbine inspection and maintenance: (1) Ability to fly in high winds (2) Ability to capture images from afar and, (3) Ability to withstand magnetic interference
So, can you use your Mavic or Phantom for windmill inspection and maintenance work? Unfortunately, no. Because wind turbines are located in areas which experience high wind speeds, you have no alternative but to opt for a very large, industrial drone. For instance, certain wind farms witness speeds as high as 20 m/s. To put things in perspective, even the M600 has a maximum wind resistance of 8 m/s. You also need to use a drone equipped with a D-RTK GNSS system — which will enable you to withstand magnetic interference ensuring a safe and stable flight.
Aerones, based in San Jose, CA has come out with a great solution for wind turbine cleaning and maintenance. The Aerones drone is a tethered drone that is connected to a water source. This is a large drone with 14 props and a payload capacity of 440 pounds. A truck or a trailer with a platform is used for takeoff and landing. For greater redundancy, this drone also comes with batteries. So, in case there is a power cut off, your drone won’t fall off from the sky. Check out the cool video below, where the Aerones drone is being used to spray deicing fluid on a wind turbine. Apart from de-icing fluid, the Aerones drone can also be used for spraying performance enhancing coating on the turbine blades.