If you know what makes a stealth bomber stealthy, you might already have an understanding of a what a stealth wind turbine is just from reading the article title. Similar to the very low radar profile of a stealth bomber, stealth wind turbines don’t reflect radar signals as much as the typical kind do. Some wind farms have been rejected for development because of their impact on aviation radar systems.
Many proposed wind turbine locations have been blocked by the French military over radar concerns. However, the military also developed a way to treat wind turbine surfaces so that they don’t interfere as much with radar systems. Vestas is manufacturing the stealth wind turbines for a 96 MW wind farm in France, which will be the largest in the country. All wind turbines located there will be stealthy.
Stealth wind turbines are not entirely new. Vestas made an announcement in 2011 about their work in this area, after completing a successful test of a new wind turbine with less radar reflectivity.
Although the development of stealth wind turbines might seem somewhat of a tangent to the wind power industry, it should be noted that an estimated 20 GW of potential wind power has been shelved due to radar interference concerns.
In developed countries with limited space for very large wind farms, there is a real concern for the disruption of air traffic control systems. Military and civilian radar systems might also be compromised by placing wind farms with conventional turbines too close. Wind farms are composed of wind turbines that turn in wind, and that are reflective. On radar screens they show up as confusing images that can cause human viewers to lose track of planes as they are flying.
Onboard navigational systems for airplanes and even marine vessels can also be confused by the presence of large wind farms. For these reasons, it makes very good sense that Vestas undertook the project to reduce the reflectivity of wind turbine blades, nacelles, and towers.
Applying the reducing materials used on stealth airplanes to entire turbine blades did not work because it reduced wind turbine performance too much. Adding the materials to the leading and trailing edges of the blades was a better solution. Replacing glass composites with radar-absorbent materials also helped. However, covering the nacelle and tower with these same materials was a good idea because this approach did not reduce wind turbine performance.
Ferrite paints and crystalline graphite are two of the radar absorbing materials that were used to make a conventional wind turbine stealthy.
Image Credit: Vestas