Meteorology News

Wind turbines such as these along the Buffalo Ridge in rural southwest Minnesota (2004) may alter large-scale wind flow over land.

Wind turbines are quickly becoming the favorite green energy source of many nations the world over as they are often considered to be virtually zero-impact.  But current research indicates wind turbines may not be as green as once thought.

Wind turbines do not block rivers or inhibit migratory species as hydroelectric dams do.  They do not emit greenhouse gasses or exhaust our dwindling supplies of nonrenewable resources such as oil or coal.  Wind turbines  generate seemingly unlimited, clean energy.  While some research has indicated wind turbines may have harmful effects on birds or other unintended consequences on the environment, most of these have been generally excused as minimal or otherwise disputed compared to the relative benefits of wind energy.  But a team of researchers from the University of Maryland have found that large-scale use of wind turbines as a power source may have an impact on our environment directly opposite that which they purport to minimize:  Climate change.

Altering air flow and wind patterns

Conservative estimates are that it would take at least a quarter-million wind turbines to meet the United States’ energy needs.  Installation of such an enormous array of wind turbines would have a profound impact on the atmospheric wind flow over the surface of the United States and perhaps even other nations.

Scientists Daniel Barrie and Daniel Kirk-Davidoff of the University of Maryland have shown that installation of a massive wind farm covering the bulk of the central United States into central Canada would effectively “steal” energy from the atmosphere.  As anyone who has studied basic physics may recall, in a closed system such as the Earth’s atmosphere, energy is conserved, that is, it cannot be created or destroyed.  As air flows through the blades of a gigantic, 300-foot wind turbine tower, the wind energy turns the blades.  This energy is robbed from the atmosphere, effectively slowing the wind speed proportionally.  The greater the array of wind turbines, the more energy is removed from the atmospheric flow and the slower the ambient wind will travel.  Slowing wind speeds by 5 or 6 miles per hour – while it sounds negligible, could have significant impacts on the large-scale atmospheric flow and yield consequences we do not yet understand.

Altering Ocean Currents

An offshore wind farm such as this one may have profound impacts not only on the air flow, but also on the ocean currents beneath the surface.

In another recent project on the impacts of wind power on our environment, Goran Brostrom of the Norwegian Meteorological Institute in Oslo has published research indicating that offshore wind farms, while perhaps less unsightly and intrusive than their land-based counterparts, may have a small yet profound impact on ocean currents in their wake.

When air flows through wind turbine blades, the path that the flow takes is slightly altered.  The net result is that there is turbulence down wind from the turbine blades.  When this turbulence occurs, rather than the ordinary laminar flow, the surface of the ocean is impacted.  This turbulence over the ocean water can cause a phenomenon known as upwelling whereby deeper ocean water is drawn up to the surface as surface water is driven down to replace it.  When the ocean “turns over” in this manner temperature flow within the body of water is altered.  Altering the upwelling patterns of an otherwise undisturbed body of water may have impacts on the currents that naturally exist as part of the large-scale flow.  As with the atmospheric air flow impacts of large-scale wind farms, the overall impact of increased ocean current upwelling is not fully understood.