Solon Economou

The truth about wind turbines: Size matters

From Jay Leno's on the west coast, to Alliance director's Christy Mihos' on the east coast, the results are in for small roof-mounted wind turbines.  They're just blowin' in the wind.

The situation came to a head recently when Massachusetts suspended a rebate program for small wind turbine projects, causing, in one case, Mashpee Commons to reconsider its proposal to mount rooftop turbines in the shopping center.  The Massachusetts Technology Collaborative, which oversees the state's major alternative energy programs, canceled the small wind initiatives because the turbines it has funded produce far less energy than originally estimated.

A sampling of the 19 small wind turbines installed using MTC grants shows an actual average power output of only 27 percent of that estimated, with the high being 59 percent and the low an abysmal 2 percent.

 The low power results from three causes:  a) Turbine manufacturers overstate the capacity of their turbines.  b) Site maps overstate the wind speeds at the various locations.  c) The turbine heights are far too low.

There are small turbines at Logan Airport.  These have underperformed.  Ditto for small turbines at Brooklyn Navy Yard.  New York City's Mayor Bloomberg has proposed dotting the city with them.  A good public relations ploy, but experts say these small turbines generate so little electricity that the economics may never make sense.

On the west coast, Jay Leno has installed a wind turbine on the garage where he works on his extensive and exquisite classic automobile and motorcycle collection.  It hasn't generated much electricity, but Leno (in whose No. 1 parking slot at NBC studios I once parked my rental car--just long enough to attract the attention of the security guards) is taking it on the chin.

On the east coast, Christy Mihos, a director of the anti-Cape Wind farm Alliance to Protect Nantucket Sound, has installed three rooftop turbines on a Christy's convenience store in West Yarmouth.  Cape & Islands Self-Reliance Corporation Executive Director Megan Amsler says, "I have been trying to get information on their performance and getting nowhere."  Joe Feraci of NSTAR Electric says, "To my knowledge only one of Christy's turbines is on-line."

In a net-metering state like Massachusetts, where you can sell excess electricity back to the grid, that says only one thing:  They're expensive pinwheels.

To Christy's credit, he has now publicly acknowledged his rooftop turbines are underperforming and blames it on their height, which is limited by local ordnance.  However, the causes for the low power generated are the three previously stated, which include low height.  It's possible that Christy, Leno, and all others who bought rooftop wind turbines may have been snookered by the sellers, who should have made a thorough and honest site analysis.  Caveat emptor.

Not all small wind turbines underperform, however.  Bob Chew, president of WindWrights in Bristol, RI, does not bother with rooftop wind turbines, but sells and installs larger and taller tower-mounted residential and commercial turbines "as a reliable supplement to existing power sources."

Even with these he is very cautious.  He says, "The bottom of the blades should be at least thirty feet higher than nearby trees or buildings.  Our minimum tower height is sixty feet, with about one hundred feet being the norm."

Chew says, "We analyze the turbines of various manufacturers before we sell any and make sure our customers are getting the expected output."  When I asked him about rooftop installations, he said, "The jury is still out."  I expect it will be out for some time.

Which brings us to the proposed Nantucket Sound wind farm in Massachusetts and the other wind farm installations proposed off the coast of Rhode Island.  It is obvious that the electricity we require can best be generated by such large-scale wind farms.  Cape Wind alone, in Nantucket Sound, will generate an equivalent of 75 percent of the electricity used by all of Cape Cod. 

Fighting wind farms and putting up pinwheels doesn't make much sense.  The simple lesson to be learned here about electricity-generating wind turbines is:  Size matters.