Wind farms are numerous in parts of Texas; scientists report new results on their effects. Credit: U.S. Department of Energy |
Large
wind farms in certain areas in the United States appear to affect local
land surface temperatures, according to a paper published today in the
journal Nature Climate Change.
The
study, led by Liming Zhou, an atmospheric scientist at the State
University of New York- (SUNY) Albany, provides insights about the
possible effects of wind farms.
The
results could be important for developing efficient adaptation and
management strategies to ensure long-term sustainability of wind power.
“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.
“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.”
Considerable research has linked the carbon dioxide produced by burning fossil fuels with rising global temperatures.
Consequently,
many nations are moving toward cleaner sources of renewable energy such
as wind turbines. Generating wind power creates no emissions, uses no
water and is likely “green.”
“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 Zhou.
There
have been a growing number of studies of wind farm effects on weather
and climate, primarily using numerical models due to the lack of
observations over wind farms.
As
numerical models are computationally intensive and have uncertainties
in simulating regional and local weather and climate, said Zhou, remote
sensing is likely the most efficient and effective way to study wind
farm effects over larger spatial and longer temporal scales.
To
understand the potential impact of wind farms on local weather and
climate, Zhou’s team analyzed satellite-derived land surface
temperatures from regions around large wind farms in Texas for the
period 2003-2011.
The
researchers found a night-time warming effect over wind farms of up to
0.72 C per decade over the nine-year-period in which data were
collected.
Because
the spatial pattern of warming mirrors the geographic distribution of
wind turbines, the scientists attribute the warming primarily to wind
farms.
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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.
“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.
While
the warming effect reported is local and small compared to the strong
background year-to-year land surface temperature variation, the authors
believe that this work draws attention to an important scientific issue
that requires further investigation.
“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.”
The
study represents a first step in exploring the potential of using
satellite data to quantify the possible effects of the development of
big wind farms on weather and climate, said Chris Thorncroft of
SUNY-Albany, a co-author of the paper.
“We’re
expanding this approach to other wind farms,” said Thorncroft, “and
building models to understand the physical processes and mechanisms
driving the interactions of wind turbines and the atmosphere boundary
layer near the surface.”
Other
authors of the paper include Lance Bosart at SUNY-Albany, Yuhong Tian
of NOAA, and Yuanlong Hu at Terra-Gen Power LLC in San Diego, Calif.
Source: National Science Foundation
