Farmers hosting wind turbines may be getting an additional benefit besides the rental payments they receive. The giant blades change the local micro-climate in ways that should benefit certain crops, several studies indicate. So far, the researchers have yet to demonstrate that crops grow better near wind farms, but their findings suggest some gain is likely.
When wind blows over turbines, it doesn't just turn the blades. Turbulence is produced downwind, mixing air at different altitudes that would otherwise have stayed separated. Professor Eugene Takle of Iowa State University measured the temperature, wind speed, and turbulence upwind and downwind of turbines when farms were operating and during an 80-minute curtailment
Takle's findings, published in the Journal of Geophysical Research: Atmospheres, were complex. He found that when the wind farms were operating, temperatures were cooler in the “near wake” immediately behind the turbine, but warmer further downwind. Generally speaking, however, their effect was to warm the area at night.
In previous work, Takle's team showed that the mixing effects of large blades bring more carbon dioxide to the leaf canopy. He has also observed a cooling effect during the day.
The economic consequences depend on the crops planted nearby. Some trees need cold nighttime temperatures to fruit properly and others become toxic in high CO2 environments. Nevertheless, more common crops such as soybeans and corn (maize) are known to do better under a combination of warmer nights, cooler days, and more carbon dioxide. The additional turbulence should also prevent the formation of frost and spread of fungi.
“On balance, it seems turbines have a small, positive impact on crops,” Takle said in a statement. This should be particularly relevant in Takle's home state, since Iowa is not only America's leading source of corn and second for soybeans, but has the most wind power per person of any American state.
Nevertheless, testing the step between potentially beneficial conditions and extra growth is not easy. Takle pointed out that differences in soil quality and rainfall will have a larger impact than turbines, making it hard to confirm that the placement of wind farms boosts crop growth.
Still, the fact that nighttime chills can be reduced downwind may make farmers more comfortable with turbines being installed on their neighbor's land. Currently, people living near wind farms miss out on rental payments and are subject to scare campaigns about so called “wind turbine syndrome".
Despite evidence consistently showing there are no negative effects from living near wind farms, the myth has been recirculated by President-elect Trump, and often leads to fierce anti-wind campaigns.