One of the major lessons learned over the past several years by the Air Force Civil Engineer Center (AFCEC) on the Massachusetts Military Reservation might be that it pays to buy local.
One of the duties of that center, formerly the Air Force Center for Engineering and the Environment, is to oversee the operation of three wind turbines which were installed to help offset the energy costs of the environmental cleanup of the Upper Cape base.
The first turbine to be erected was the 1.5-megawatt German machine in the southwestern portion of the base, not far from the part of Falmouth where Route 28 and Route 151 intersect. It went up at the end of 2009.
Since then, it has had a series of problems. Assistance with the maintenance of the European-made machine has been hampered by distance, language barriers, and slow response times, said Rose H. Forbes, the turbine project manager. At the time, she said, the major American manufacturer of industrial-scale wind turbines was looking for orders of 10 or more machines and would not supply just one or two.
When it came time to order the two 1.5-megawatt wind turbines now in the northern area of the base, not far from the Market Basket in Sagamore, the wind turbine market had changed, and the program was able to buy American-made turbines. Those turbines went up in November 2011.
Not only did those wind turbines perform as expected, US-based General Electric representatives were responsive to any problems or questions that did arise, Ms. Forbes said.
The wind turbine operation is jointly funded by the Air Force and the Army, which have each taken responsibility for the cleanup of different sources of the pollution that affect Cape Cod’s sole source aquifer, sending plumes of contamination into the groundwater.
Electrical costs for the cleanup program ranged from $2 million in 2009, when the first wind turbine went online, to $1.6 million in 2012.
Expectations Not Met
When it went up, the German turbine was expected to offset 25 to 30 percent of the cleanup program’s utility costs and pay for itself within eight years.
From its startup in December 2009 through November 2012, that turbine did not live up to expectations. During that time, it should have produced 11,430 megawatt-hours of electricity; instead it generated 8,040 megawatt-hours. That amount, although less than expected, still resulted in a credit of approximately $1 million and offset carbon dioxide emissions by 5,266 tons, according to AFCEC statistics.
Performance of that machine was impacted by lower-than-average wind speeds, a number of mechanical problems, and poor service by the manufacturer, they said.
Those issues included worn generator brushes and loss of charging capacity in backup systems.
A wind turbine’s “yaw drive” orients the motor housing of a turbine to the wind, and a major component of that drive is a gearbox. Diagnostic evidence suggests that the German gearbox may be failing due to a bad bearing and, possibly, because of poor design, the AFCEC reported.
Ms. Forbes said this week, however, that a “yaw converter error that lasted for over a year” has recently been corrected, at very little expense, and the turbine is currently operating well.
It is currently estimated that it will now take the wind turbine approximately 10 years, or until 2019, to pay for its cost. That might be extended to 11 or 12 years, if the gearbox needs to be replaced.
Douglas C. Karson, AFCEC community involvement lead, said a rough estimate of the cost of that replacement is between $300,000 and $500,000.
In contrast, the two GE turbines have performed as anticipated. In fact, AFCEC said, they would have performed better than expected except for shutdowns for electrical storms, a two-week shutdown in 2011 at NStar’s request due to work that company needed to perform on its transmission line, and a few minor mechanical problems.
The two turbines were projected to produce 7,620 megawatt-hours annually; over the course of a year they actually produced 7,645 megawatt-hours. In a little more than a year, from November 8, 2011, to November 26, 2012, their operation resulted in a credit of $923,133.
Another tenant of the military reservation, the 6th Space Warning Squadron that operates Pave PAWS, is already working on the construction of its own two 1.5-megawatt wind turbines, not far from AFCEC’s two GE machines. They are expected to offset approximately half of the radar site’s electricity costs.
That squadron, part of the Air Force Space Command, has been taking advantage of the lessons learned by AFCEC.
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