May 1st, 2012 by Joshua S Hill
A new study has found that land surface temperatures underneath and around large wind farms in west-central Texas have increased as a result of the introduction of the wind farms, especially at nighttime.
“This study indicates that land surface temperatures have warmed in the vicinity of large wind farms in west-central Texas, especially at night,” says Anjuli Bamzai, program director in the National Science Foundation’s (NSF) Division of Atmospheric and Geospace Sciences, which funded the research which was published Sunday in the journal Nature Climate Change.
Notably, as American Wind Energy Association (AWEA) CEO Denise Bode states: “This study says nothing about wind energy and global climate, and casts no doubt on all the other studies that find wind power is one of the best ways to address climate change. The study merely examined the effect of local air mixing at the site of a wind farm, which has nothing to do with climate because no heat or heat-trapping gases are being added to the atmosphere.”
“The observations and analyses are for a relatively short period, but raise important issues that deserve attention as we move toward an era of rapid growth in wind farms in our quest for alternate energy sources,” Bamzai added.
“We need to better understand the system with observations, and better describe and model the complex processes involved, to predict how wind farms may affect future weather and climate,” said Liming Zhou, lead author of the study.
With the increase in the number of wind farms being installed, there has been a corollary increase in studies attempting to determine the effects wind farms have on the weather, climate, and local ecosystem. A previous study from Iowa State University has found that wind turbines may benefit crops due to their air circulation effects.
Zhou’s team analysed satellite-derived land surface temperatures from regions around large wind farms in Texas for the period of 2003 to 2011. They found a nighttime warming effect over wind farms of up to 0.72 degrees Celsius per decade over the nine-year period in which their data had been collected. The year-to-year land surface temperature over wind farms shows a persistent trend over their study period, consistent with the increase in the number of operational wind turbines being installed.
“This warming effect is most likely caused by the turbulence in turbine wakes acting like fans to pull down warmer near-surface air from higher altitudes at night,” said Somnath Baidya Roy of the University of Illinois at Urbana-Champaign, a co-author of the paper.
However, the researchers are quick to note that this study does not represent a global summary.
“The estimated warming trends only apply to the study region and to the study period, and thus should not be interpolated into other regions, globally or over longer periods,” Zhou said. “For a given wind farm, once there are no new wind turbines added, the warming effect may reach a stable level.”
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