Wind results from unequal temperatures. This can be a vertical wind or a horizontal one. Vertical winds are responsible for the sometimes rapid rise or fall of planes. The same turbulent conditions that might require you to “return to your seat and fasten your seatbelt” makes wind turbines less efficient.
Additionally, different horizontal wind speeds at different heights, also known as wind shear, can put stress on large turbine blades. Studies have been measuring horizontal wind speeds and their duration to determine the wind energy potential of an area for awhile. Now, a new study concludes that unstable atmospheric conditions can reduce wind turbine performance by an average of 15%. The research was conducted by Sonia Wharton of the Lawrence Livermore National Laboratory (California) and Julie Lundquist from the University of Colorado.
Turbulence can also be caused by nearby obstructions. Mountains, man-made structures, sea cliffs, and even vegetation can cause turbulence. Under such conditions, the wind may shift direction quickly. The wind turbine may not react as fast. This puts stress on the structure, in addition to causing performance issues.
A place particularly bad for turbulence also suggests solutions. Cities have many obstructions. It has been found that the air is disturbed long before and after obstructions. But, beyond, the turbulence zone wind speed is increased. It has been proposed that small wind turbines be placed on NYC buildings that could take advantage of the increase in wind speed.
Vertical Axis wind turbines don’t need to change directions to meet the wind, and the pitch of the blades can take advantage of updrafts from below the edge of a building. Buildings can also be shaped to channel the wind flow.
Wind can be an economical source of power with the right location. Due to the lack of obstructions out at sea, offshore wind is less turbulent. It also tends to be stronger and more constant. Avoiding wind turbulence is one way to get the greatest amount of energy while reducing costs. Hence, there is a strong push to advance offshore wind technology and install a lot more wind power over the rushing sea.
Photo Credit: Uairo1 (CC by 2.0 license)