Turbulence now bad wind farms as it decreases the energy they capture

Supercomputer simulations revealed the negative effects this atmospheric condition has on wind farms.

Wind turbines at an offshore wind farm. | Photo Credit: STEPHANE MAHE/REUTERS

AN improved understanding of interactions between wind farms and the local atmosphere can help optimise wind farm designs for greater energy output.

Supercomputer simulations carried out by scientists, led by Anja Stieren, of the University of Twente in The Netherlands, have shown that negative shear “baroclinicity”, an atmospheric condition, can reduce wind velocity and enhance turbulence above wind farms, thus decreasing the energy the farms can capture. The results add a surprising new nuance to physicists’ current understanding of the ways in which turbulence can boost wind farms yields. Until now, enhanced turbulence was associated with greater streamlining of energy into wind farms and improving their performance.

Baroclinicity, or a height-dependent variation in pressure difference, arises due to horizontal temperature transitions, like the transition of flow dynamics from land to sea or sloping terrains. Depending on its alignment with the horizontal temperature or density gradient, the pressure gradient can steepen, flatten, or change its direction with height. These changes can lead to increased turbulence and other effects.

The results of the present simulations work, which were published in the latest issue of Physical Review X Energy, however, have shown that negative shear baroclinicity-generated turbulence creates an upward flux that diverts wind energy away from the farm. It also reduces wind velocity at the turbine height and can decrease the overall energy collected at wind power plants.