Factcheck: do wind farms increase climate change?
- 07 Feb 2012, 12:00
- Robin Webster
You may have seen the
rather startling claim in the Mail that
Wind farms can actually INCREASE climate
change by raising temperatures and causing downpours, warn
Wind farms increase climate change? It's certainly an
intriguingly counter-intuitive story. The article also has the
Temperatures can fall by 4C downwind of
Wind farms cause temperatures to rise, and fall?
This is a neat example of one newspaper rehashing an article from
another - in this case the Mail article is inspired by a report in
the Sunday Times covering work by Dr
Somnath Roy, an atmospheric scientist from the University of
Roy's most recent paper,
published in the Journal of Wind Engineering and Industrial
explores the possible impacts of such
wind farms on local hydrometeorology using a mesoscale model
equipped with a rotor parameterization based on data from a
commercial wind turbine. Results show that wind farms significantly
affect near-surface air temperature and humidity as well as surface
sensible and latent heat fluxes.
Remarkably, this appears to mean that wind turbines facilitate
the movement of air - as the Sunday Times explain in somewhat
….the day ground-level temperature
behind the turbines was up to 4C lower than in front. The turbines'
blades scooped warm air away from the ground and pushed cooler air
above it downwards. At night, when the ground cooled and the air
above was warmer, the effect reversed.
[Roy] believed the effects were caused
by turbines reducing overall wind speed and creating turbulence.
The rotating blades churn the air, bringing high-level air down to
earth and lifting up air that had been sitting just above the
ground to a much greater height. The resulting vortices can extend
far downwind depending on the size and number of turbines.
So, this research uses regional computer modelling to suggest
that wind turbines lower temperatures in the region of the turbines
a bit in the day, and raise it a bit at night... by moving air
around. It did conclude that there could be "significant
implications for future energy and land use policy" as use of wind
Does this amount to 'actually INCREASING' climate change? Possibly
What about 'cause downpours'? This conclusion doesn't appear in
any of the studies referred to in the Mail article.
It could be sourced to a study published in Environmental
Research Letters and cited in the Times article, which looked
at the impacts on regional weather patterns of a (hypothetical)
"giant wind farm" which could provide 20% of the electricity
requirements of the USA.
Such a "giant" wind farm would have impacts on regional weather
patterns, but given Britain's current rate of wind build, we're
probably safe from giant renewables-triggered deluges.
Still, on the blogs it's just a short step to
Wind Farms Cause Global Warming, some Scientists Say.