Wednesday, March 28, 2012

The Windiest Time of the Year

Spring always seemed like the time of the year to fly a kite when I was growing up.  I didn't know much about what it took to get a kite high off the ground, but fortunately I had an older brother who did.  I can remember times when we got a box kite up to about three hundred feet above the ground.

Across most of the country, spring is the windiest time of the year.  Wind speeds and wind power tend to be 3-5 times stronger in March and April than in July and August.  In the dust bowl days most of the dust storms were in late winter and spring.  That continues to be the case in the Plains today.

Gusts may come and go, but on average there’s more wind now than at any other time of the year. The chart below shows the amount of electricity that would be generated by a single 1.5 megawatt wind turbine, with each point representing a running nine-day average. Historically, March 21st is the windiest single day of the year.
Click here for an interactive chart that represents the same data, but you can hover over any point to get the relative wind power for any given day (again, based on a nine-day average). 

Daily wind power generated at a single turbine, 9-day average (Wind Power (x 1000 kWh)).  Image credit: Climate Central.

The U.S. Department of Energy has generated national and state wind maps, illustrating average annual wind speeds across the country. While the Great Plains are easily the windiest parts of the country, the national wind maps show that the Midwest, the Northeast and all along the national coastline, average annual windspeeds are usually 6.5 mph or greater.

Wind resource maps for South Carolina and the U.S.  Image Credit: U.S. Department of Energy.

Wind resource maps show the predicted mean annual wind speeds at an 80-meter (m) height, presented at a spatial resolution of about 2 kilometers (interpolated to a finer scale for display). Areas with annual average wind speeds around 6.5 meters/second and greater at an 80-m height are generally considered to have a resource suitable for wind development. Utility-scale, land-based wind turbines are typically installed between 80-100 meters.

The immediate coast and coastal waters offer the best potential for wind farms in South Carolina.  In fact, Clemson University has been building what will be the world’s largest wind-turbine drivetrain testing facility in North Charleston.  The facility is expected to start operations later this summer.  Clemson University has been studying the feasibility of wind farms off the coast of South Carolina.