Another downside to wind power

By Kennedy Maize

Here’s an interesting new wrinkle on wind power, from a researcher at the University of Illinois. According to Somnath Baidya Roy, turbulence from large wind farms can harm growth of crops in the local countryside.

Baidya Roy notes that in recent years, wind power has moved from small, isolated turbines to large farms containing a large array of turbines connected to the electric grid. In northwest Iowa, he observes, a wind farm has more than 600 wind machines, sending some power to more than 140,000 homes.

If wind is going to make a greater contribution to national generating capacity, the wind farms must be far larger, he says. “If wind is to be a major player in global electrical production,” says Baidya Roy, “we have to think in terms of even larger scales – of say, thousands of turbines per wind farm. Such a wind farm could replace 10 coal-fired power plants, but with so many turbines, turbulence could generate huge problems.”

Turbulence creates two environmental externalities for wind generation, says Baidya Roy. First, turbulence can interfere with the windmills, reducing their efficiency. On top of that, turbulence from the turbine rotors can also mess up local ground temperature and moisture levels. “Turbulence creates stronger mixing of heat and moisture,” he says, “which causes the land surface to become warmer and drier. This change in local hydrometeorological conditions can affect growth of crops within the wind farm.”

What to do? Baidya Roy suggests greater understanding of land use planning, looking for places to site wind farms where wind flows freely, without obstructions such as trees and mountains. That means wind developers should avoid tops of mountain ranges, where the wind resources are plentiful, but the surface friction is high. Baidya Roy says “frictional dissipation” is the enemy of efficient wind projects. He is using a 25-year collection of data from surface weather stations, radiosonds and satellites to map wind’s frictional dissipation around the world.

Where are the wind wonderlands? According to Baidya Roy’s mapping project, eastern and central Africa, western Australia, eastern China, south Argentina and Chile, northern Amazonia, the northeastern U.S., and Greenland are the best hosts for low-impact wind farms.