Wednesday 2 May 2012

Wind farms linked to climate change

Wind farms can cause climate change, according to new research, that shows for the first time the new technology is already pushing up temperatures.
Usually at night the air closer to the ground becomes colder when the sun goes down and the earth cools. But on wind farms the motion of the turbines mixes the warmer air higher in the atmosphere with the ground-level air, pushing up the overall temperature.
Satellite data over a large area in Texas, covered by four of the world's largest wind farms, found that over a decade the local temperature went up by almost 1°C as more turbines were built. This could have long-term effects on wildlife living in the vicinity of larger wind farms. It could also affect regional weather patterns as warmer areas affect the formation of cloud and even wind speeds. And, as even bigger wind farms are built around the world, there are calls for further research into whether it is likely to affect climate change on a larger scale.

Texas is the largest producer of wind power in the US. It is reported that China is erecting 36 wind turbines every day. Liming Zhou, Research Associate Professor at the Department of Atmospheric and Environmental Sciences at the University of New York, who led the study, said further research was now needed into the effect of the new technology on the wider environment. "Wind energy is among the world's fastest growing sources of energy. The US wind industry has experienced a remarkably rapid expansion of capacity in recent years," While converting wind's kinetic energy into electricity, wind turbines modify surface atmosphere exchanges and transfer, of energy, momentum, mass and moisture within the atmosphere. These changes, if spatially large enough, might have-noticeable impacts on local to regional weather and climate."

The study, published in the scientific journal Nature, found a warming trend of up to 0.72°C per decade as more turbines were built. The team studied satellite data showing land surface temperature in west-central Texas: The study said: "Despite debates regarding the possible impacts of wind farms on regional to global scale weather and climate, modelling studies agree that they can significantly affect local scale meteorology."
"Our results show a significant warming trend of up to 0.72°C per decade, particularly at night-time, over wind farms relative to nearby non-wind farm regions. We attribute this warming primarily to wind farms as its spatial pattern and magnitude couples very well with the geographic distribution of wind farms. The spatial pattern of the warming resembles the geographic distribution of wind turbines and the year-to-year land surface temperature over wind farms shows a persistent upward trend from 2003 to 2011, consistent with the increasing number of operational wind turbines with time," said Prof Zhou. However he pointed out that the most extreme changes were at night and the overall, changes may be smaller. In addition, they were much smaller than the estimated change caused by other factors such as man made global warming. "Overall, the warming effect reported in this study is local and is small compared to the strong background year-to-year land surface temperature changes," he added.
Prof Steven Sherwood, co-director of the Climate Change Research Centre at the University of New South Wales in Australia, the research was "pretty solid". "This makes sense, since at night the ground becomes, much cooler than the air just a few hundred meters above the surface,, and the wind farms generate gentle turbulence near the ground that causes these to mix together, thus the ground doesn't get quite as cool."
Source: Daily Telegraph, 30th April

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