Our global reliance on fossil fuels may soon come to an end. Renewable energy sources are on the uptick, with report after report detailing their proliferation across the globe. In the wake of the Paris agreement, it’s unlikely to slow down anytime soon, so expect advanced solar power plants and wind farms to keep popping up all over the place.
Wind farms have often been the subject of intense debate. Although they are clearly useful sources of renewable energy, they aren’t always reliable – after all, the wind isn’t always blowing – and some see them as a blight on the landscape. Scientists have also wondered if their alteration of the local wind currents is having an effect on the surrounding environment.
A new study, published in the journal Environmental Research Letters, has revealed that they do indeed have an effect: Land-based wind farms appear to slightly warm the ground beneath them, although offshore wind farms do not have any noticeably adverse ecological effects.
“For a long time there have been some concerns about what effects wind farms could have on the local climate and the land surface,” study co-author Professor Stephen Mobbs from the University of Leeds, director of the National Centre for Atmospheric Science, told BBC News. “To be honest, it was mostly speculation with nothing very concrete. We set out to actually measure what was going on.”
Black Law wind farm. Stuart Brooks/Wikimedia Commons; CC BY-SA 2.0
Black Law wind farm in Scotland, which has been in operation since 2005, was chosen by the researchers for their study. It’s one of the largest terrestrial wind farms in the U.K., capable of generating 124 megawatts of power, using 54 turbines spread over 18.6 square kilometers (7.2 square miles).
By installing humidity and temperature sensors across the site, the researchers were able to track how the local “microclimate” changed when the turbines were either on or off. When they’re off, the environment behaves as it normally would: The ground is cooler than the air above it, which at the height of a turbine is a few degrees warmer.
When the turbines are rotating, this warm air is forced down to the ground, which moves the cooler layer up into the air. The net effect of this mixing is that the air just above the ground becomes increasingly humid and warmer – by no more than just 0.25°C (0.45°F) at night.
Although there is definitely a climatic effect associated with wind farms, the effect itself is relatively insignificant in terms of its environmental impact. “Because we have been able to definitively detect the effect, we can also definitively say that the effect is extremely small and it is not something people should be worried about,” Mobbs added.
The researchers do note that, although they couldn’t directly measure it, warming at this level could alter the respiration of plants to the point where their net carbon dioxide intake could fall slightly. However, they also point out that during seasons where plant growth is low, the same level of warming would increase their ability to withdraw carbon dioxide from the atmosphere.
In any case, this extremely minor environmental complication pales in significance to the contribution wind farms make to the move away from climate change-inducing fossil fuels.