Sunday, March 23, 2008

A Tour of Desert Sky Wind Farm

"Wind farms are simple."

Roy Blackshear, Operations Manager at American Electric Power's Desert Sky Wind Farm, was clearly spoken as we talked about the technology and operation of large scale wind. As I mentioned in a previous post, Desert Sky is a 160.5 MW, 107 windmill installation covering 16 square miles of Indian Mesa in Iraan, TX. Here are a few things I learned, and a few pictures I took home from my visit.

Each of the turbines is a self-contained independent power plant, with no operator intervention required. A wind vane mounted on the rear of the nacelle controls yaw by engaging two 1000 lb motors. Because every degree of misalignment with the wind direction costs the square of the error, this system is routinely checked. Power curves for each independent plant are stored in a historical database and are run regularly against the expected trendline.

A map of the wind farm shows a strange, leaflike arrangement, as turbines are branched according to the primary wind direction (150 deg SE) and follow the peaks and ridges of the land. The turbines are designed to face a (somewhat) constant velocity laminar airflow such that they are arranged in lines perpendicular to the wind, each turbine separated by 2 1/2 blade diameters (d = 70 m) to avoid interference with one another. Each line of turbines is separated by 1/2 mile (parallel to the wind) to avoid each other's envelope of influence.

Desert Sky was built in 2001, so has some experience to share with the rising wind business in Texas. The billion dollar BP Wind project in construction across I-10 will confront transmission line capacity limits which currently curtail the amount of electricity that can be sold. A shortage of skilled technicians drives the pricetag for a mechanic into the 6-figure range, and competition among wind farms to retain their workforce will continue as more installations come online.

Mr. Blackshear spoke at the annual Renewable Energy Conference held at UT in 2006, but said he will probably be cutting down on these types of appearances. You won't find many in his position willing to take the time off to make the trip, so if Dr. Grady does manage to sign him on for a presentation this fall, I highly recommend you hear it.

An element of scale: On the top right photo, I am that tiny black dot at the center of the tower.

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