Another “Low Wind Speed Turbine” Question

By Lee Consavage

On January 29th, the following Letter to the Editor appeared in our local newspaper, the Portsmouth Herald (, addressing the new community wind turbine to be erected in Kittery, Maine. This letter was submitted by a Kittery resident who felt the Entegrity 50 kilowatt wind turbine selected by the Kittery Energy Committee would not perform as well as the Emergent wind turbine since the Emergent has a lower “cut-in” wind speed. The Kittery community wind turbine is discussed in more detail in the About Us section of this website.

Let me be clear – THERE IS VERY LITTLE ENERGY AVAILABLE IN LOW SPEED WINDS! No wind turbine is capable of performing well under low wind speed conditions. Here’s the letter written by the Kittery resident. Immediately following is my Letter to the Editor to address the concerns raised by the Kittery resident.

Kittery made wrong choice of wind turbine

Jan. 29 — To the Editor:

I am 100 percent pro-wind, but 50 percent against this particular turbine (EW-15) being installed in Kittery at the height they are asking for. The EW-15 has been installed at two other locations in Maine. One (Blueberry processor in Orland, Maine) took it down because of bad PR — it did not turn.

This is a stiff wind turbine, and Kittery is in a low wind speed regime. The committee looked at the cost of the three turbines proposed and almost totally ignored if it would produce the power. Saco has a wind regime that is about 10-15 percent than higher than Kitterys wind. This turbine should be installed at 50 meters — another 35-plus feet higher than the permit calls for.

On the other hand, if the Town Council would look at the power curve of the three machines that came in with a bid rather than the overall cost, they might have picked the correct machine, that would turn in the winds in Kittery. The Emergent proposal had added a 30 percent markup to the cost of the turbine it proposed. Had the committee bothered to look at the power curve and called the proposed supplier of the machines, it probably would have made a different choice.

Had Emergent added the typical 8-11 percent markup, the cost would be comparable and the machine will turn at the lower wind speeds than the one that was low bidder. The lighthouse proposal clearly stated it was only lukewarm on this project because of the light winds, and their machine has a better power curve than the EW-15 has as well.

The Orland machine referenced on page 57 on this report written at UMaine came down in November 2007. They offered it for sale in March 2007 and it was a big disappointment to the Blueberry processor and Endless Energy Corporation.

This wind turbine works perfectly fine in Alaska, Texas and Kansas, where there are stiff winds. I am against permitting this particular manufacturers machine because their marketing practices are deceptive, initially telling us that the payback was six years and orally promising 90,000 kWhr/annual production. When they came in with their final bid it was span of production dropping to 80,000 kWhr/annually and they would not put it in the contract.

The Kittery energy committee has 12 or more months worth of data at 13 meters. The data was extrapolated to 120 feet. I believe the extrapolation is at least 12 percent too high. The mean monthly data was plotted out and two different versions were plotted up and shown and I am not sure if either version is correct.

Unless the data is verified by someone and the extrapolation shown in better detail, I am against purchasing this machine unless it is placed up higher. The AWS Truwind data shows an annual wind speed of 4-4.5 m/s at 30 meters (~98 ft) and 5-5.1 m/s at 50 meters.

The bulk of the wind speeds are therefore lower than the average annual wind speed at the proposed 125 feet. This particular turbine does not begin to turn until the wind speed reaches 4.6 m/s. The two other wind turbines looked at start turning at 3.2 m/s and 4.0 m/s and both will produce more power at the wind speeds in Kittery.

A comparison of the three machines was provided in table format by Seacoast Consulting, but the most important piece of data on the three proposals — the cut on wind speed was not in the comparison. The committee chose the machine based solely on the cost.

If Kittery were purchasing a boat and a bid came in at a cost of $190,000 and the other came in at $210,000, and the seller of the two boats did not tell you that the first boat would not float but the second boat was sea worthy, it would be a poor choice to buy the cheaper boat. Kittery should do the same with a wind turbine. Buy a turbine that will turn — not one that will sit there for all but two-three months and not turn.

The wind data and its interpretation and interpolation that this decision is based on should be shown to the public. Kittery should ask for a second round of proposals and make a choice based on the best production for the investment dollar, not on the cheapest bid. This should be an informed decision. This decision was made too quickly and without adequate analysis.

Suzanne Sayer, Ph.D.

Kittery, Maine


The following is my own Letter to the Editor in reply to some of Suzanne’s concerns:

Kittery Made A Wise Decision In Selecting Entegrity Wind Systems

To The Editor:

Our company provides unbiased, practical advice to anyone considering purchasing a renewable energy system such as a wind turbine. We were therefore very excited and honored to be asked by the Kittery Energy Committee to participate in their discussions concerning purchasing a wind turbine.

The energy committee has been investigating the feasibility of installing a wind turbine since 2006 and has collected over a years worth of wind speed data at the proposed site for the turbine, with the results looking promising. Recently receiving a $50,000 renewable energy grant from Maine, and overwhelming support from the residents of Kittery, allowed the energy committee to request bids from wind power companies throughout the United States.

All bids received listed the expected annual energy production of each turbine and the expected annual maintenance cost. Entegrity Wind Systems offered the lowest installation and maintenance cost per kilowatt-hour to operate and maintain the wind turbine. In fact the cost to install the Entegrity turbine included a 5-year 100% “bumper-to bumper” maintenance plan which requires Entegrity to fully maintain the turbine and fix anything requiring fixing for 5-years, at no additional cost to Kittery. Entegrity was the only company to offer such a plan.

In a January 29th Letter to the Editor, Suzanne Sayer of Kittery question the decision to select Entegrity based on cost alone. She stated the energy production of each turbine should have been the deciding factor. Ms. Sayer also stated that the Emergent turbine “will turn at the lower wind speeds than the one that was low bidder.”

Ms. Sayers will be happy to learn that the energy committee did factor in the annual energy production of each turbine before making a final selection. Our company was able to break down the cost per kilowatt-hour based on the annual energy production of each turbine and the maintenance cost the town of Kittery would need to spend each year to maintain the turbine and its associated components. Enetgrity’s cost per kilowatt-hour and their free maintenance plan offered the quickest payback and was therefore the most appropriate selection for the town.

Additionally, the term “Low Speed Wind Turbine” is sort of an oxymoron since there is very little power available in low speed winds. A lower “cut-in” speed will not improve the performance of wind turbines when there is very little wind. Certain laws of physics govern the performance of wind turbines, most notably wind speed and swept area of turbine blades. The amount of power available in wind is related to the cube of the wind speed, so doubling the wind speed results in an 8-fold increase in energy available to be captured by the turbine. Similarly, reducing the wind speed by half results in a 8-fold decrease in energy available to be captured by the turbine. The energy production of all wind turbines are based on these same laws of physics.

While it is true that wind turbine manufacturers are able to tweak their turbines to perform better under certain wind regimes, it is also true that no turbines perform well under low wind conditions. Spending more money on a larger turbine with higher maintenance costs will not resolve a low wind issue. If Kittery truly does have winds that are too low to make wind power viable, then it is better to have spent the least amount of the taxpayer’s money to gain this knowledge.

All discussions by the Kittery Energy Committee are open to the public. Ms. Sayer was invited to attend every meeting and she did attend many of the wind power meetings, including the deliberation to select and award the wind energy contract to Entegrity. At no point prior to the awarding of the contract did Ms. Sayer express doubts about the selection. I know Ms. Sayer is a concerned Kittery resident who only wants to ensure the taxpayers of Kittery get the biggest bang for its buck. I hope this letter helps ease some fears expressed by Ms. Sayer. The Kittery Energy Committee has worked tirelessly to ensure Entegrity was the best selection.

Congratulations to the Kittery Energy Committee, the Town Manager and to all residents of Kittery in taking this important step to reducing its reliance of fossil fuels. You’re a great example to all who live in the seacoast area!


Lee Consavage, PE

Seacoast Consulting Engineers

Eliot, Maine


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