* Area over large Texas wind farms shows temperature rise
* Could have wider effect as more farms are built
* More studies needed – researchers
By Nina Chestney
LONDON, April 29 (Reuters) – Large wind farms might have a
warming effect on the local climate, research in the United
States showed on Sunday, casting a shadow over the long-term
sustainability of wind power.
Carbon dioxide and other greenhouse gases from burning
fossil fuels contribute to global warming, which could lead to
the melting of glaciers, sea level rise, ocean acidification,
crop failure and other devastating effects, scientists say.
In a move to cut such emissions, many nations are moving
towards cleaner energy sources such as wind power.
The world’s wind farms last year had the capacity to produce
238 gigawatt of electricity at any one time. That was a 21
percent rise on 2010 and capacity is expected to reach nearly
500 gigawatt by the end of 2016 as more, and bigger, farms
spring up, according to the Global Wind Energy Council.
Researchers at the State University of New York at Albany
analysed the satellite data of areas around large wind farms in
Texas, where four of the world’s largest farms are located, over
the period 2003 to 2011.
The results, published in the journal Nature Climate Change,
showed a warming trend of up to 0.72 degrees Celsius per decade
in areas over the farms, compared with nearby regions without
the farms.
“We attribute this warming primarily to wind farms,” the
study said. The temperature change could be due to the effects
of the energy expelled by farms and the movement and turbulence
generated by turbine rotors, it said.
“These changes, if spatially large enough, may have
noticeable impacts on local to regional weather and climate,”
the authors said.
MORE RESEARCH NEEDED
But the researchers said more studies were needed, at
different locations and for longer periods, before any firm
conclusions could be drawn.
Scientists say the world’s average temperature has warmed by
about 0.8 degrees Celsius since 1900, and nearly 0.2 degrees per
decade since 1979. Efforts to cut carbon dioxide and other
greenhouse gas emissions are not seen as sufficient to stop the
planet heating up beyond 2 degrees C this century, a threshold
scientists say risks an unstable climate in which weather
extremes are common.
The Texas study found the temperature around wind farms rose
more at night, compared with nearby regions. This was possibly
because while the earth usually cools after the sun sets,
bringing the air temperature down, the turbulence produced by
the farms kept the ground in their area warm.
Previous research in 2010 by other U.S. scientists found
wind farms could make the nights warmer and days cooler in their
immediate vicinity, but those effects could be minimised by
changing turbines’ rotor design or by building the farms in
areas with high natural turbulence.
That research was based on evidence from two meteorological
towers over a six-week period.
Although the warming effect shown in that study and the
latest research is local, and small compared to overall land
surface temperature change, the findings could lead to more
in-depth studies.
The authors of the study released on Sunday said: “Given the
present installed (wind farm) capacity and the projected
installation across the world, this study draws attention to an
important issue that requires further investigation.”
“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.”
Commenting on the study, Steven Sherwood, co-director of the
Climate Change Research Centre at the University of New South
Wales in Australia, said: “Daytime temperatures do not appear to
be affected. This makes sense, since at night the ground becomes
much cooler than the air just a few hundred metres above the
surface. The wind farms generate gentle turbulence near the
ground that causes these to mix together, thus the ground
doesn’t get quite as cool.”
(Edited by Pravin Char)
