Wind Energy Creates a Warming Effect, Study Finds
Clearly, wind energy is favored to its fossil fuel counterparts in terms of its environmental footprint. Zero greenhouse gas emissions. Zero global warming potential. Zero heat islands. Simply, wind energy seems to be a perfect part of the solution to a climate change problem.
At least, this is what we thought.
Until recently, when scientists discovered a surprising link between wind farms and rising land surface temperatures. As it turns out, wind farms may stir air in an atmospheric boundary layer a bit too much — enough to produce a noticeable warming effect after the sundown.
The study, which was published in Nature Climate Change in April, is one of the first ones to consider interactions between wind turbines and the atmospheric boundary layer near the land surface. A team of scientists from State University of New York at Albany and several other institutions presents a long-term observational evidence of the effects of wind farms on surface temperatures. Over the span of nine years, they carefully observed land surface temperatures around four wind farms in west-central Texas. Guided by the satellite data, the team found that wind farms are responsible for "a significant warming trend of up to 0.72°C per decade, particularly at night-time".
"We attribute this warming primarily to wind farms", the study confirms.
The researchers suggest that the observed warming effect is created by an enhanced vertical mixing behind the wind turbines. When wind turbines rotate, they create wakes behind them. The turbulent wakes can travel long distances downwind — and stir up air as they go. This is similar to wakes created by motorboats on a lake’s surface.
Yet, during the nighttime, the atmospheric boundary layer is very stable and thermally stratified. Because of the efficient radiative cooling of land surface, air lying closest to the land surface is coldest. From there up, its temperature increases. Therefore, warmer air will typically loom above cooler air. As wind turbines continue to spin during the dark hours, they bring warmer air close to the surface. This creates a warming effect, which is not observed in the absence of wind farms.
Article continues at ENN affiliate, Clean Techies
Wind Turbine image via Shutterstock