Commentary by Paul Lindsey, former naval nuclear officer,
Wind turbines of all sizes have plenty of advocates, because the promise of electricity with zero fuel cost is very attractive. Santa Fe County has a 10 kW Bergey Excel turbine on a 120 ft tower at their Public Works Complex. The inclusion of the wind turbine at the new complex was justified by stating that it would provide 3-6.8% of the facility’s electricity. Recently, the Sierra Club endorsed Santa Fe County Commissioner Virginia Vigil for the District 3 Public Regulation Commission position. In her responses to the Sierra Club questionnaire, Ms. Vigil cited her support for the 12kw (sic) wind turbine. Now that it’s been in operation for more than two years, has the $75,000 spent by Santa Fe County been a good investment?
Umm, no. The wind turbine is averaging 5780 kWh/yr. At 9 c/kWh, that’s a total annual electricity cost savings of $520, or $43.33 per month. At that rate, it will take 144 YEARS to payback the installation expense, assuming that there a no repair or maintenance costs. That is also 3-5 times the design life of the turbine, so the County would have to buy and install a new turbine (currently $32K each) at least two more times. The cost of a replacement turbine alone puts the County in a tail chase, because the payback time for $32,000 is 11 years longer than the maximum expected design life, unless the cost of electricity to Santa Fe County rises to 11 c/kWh. To payback the original $75K turbine cost (which includes the tower, installation and connection expenses) within 50 years, the cost of electricity would have to go up to 26 c/kWh!
Here is the wind turbine’s generation data for the last year (well, 352 days), provided by a representative of the Santa Fe County Public Works Dept’s Office of Renewable Energy and Energy Efficiency. Be very careful reading the data, as the intervals between readings vary from 22 to 63 days:
Date
|
Accumulated Energy Reading
|
Difference from Previous
|
Nine Cents / kWh
| |
5/10/2011
|
5,448
|
Production in kWh
|
kWh / day
|
Value per interval
|
6/1/2011
|
6,225
|
777
|
35.32
|
$69.93
|
7/1/2011
|
6,914
|
689
|
22.97
|
$62.01
|
8/1/2011
|
7,329
|
415
|
13.39
|
$37.35
|
8/31/2011
|
7,654
|
325
|
10.83
|
$29.25
|
10/3/2011
|
7,950
|
296
|
8.97
|
$26.64
|
11/30/2011
|
8,688
|
738
|
12.72
|
$66.42
|
2/1/2012
|
9,429
|
741
|
11.76
|
$66.69
|
2/29/2012
|
9,944
|
515
|
18.39
|
$46.35
|
4/26/2012
|
11,023
|
1,079
|
18.93
|
$97.11
|
Don’t fault the wind turbine. There’s just not enough consistent, sufficient wind speed at this location. Someone either forgot to “run the numbers”, or intentionally put style ahead of substance. The Bergey Excel 10 is an excellent, simple design. It has been made in America for over 30 years, with over 1,800 installed worldwide. It has a design life of 30-50 years. It can produce a lot of electricity, with one caveat: the site has to have sufficient, consistent wind (at least 10 mph per Bergey literature). It’s AWEA rated to produce 13,200 kWh per year at an average 11 mph wind speed. Unfortunately, the Santa Fe County installation is producing less than half of that amount. A wind turbine’s output is subject to the cube rule, meaning that if the actual wind speed is half of the projected wind speed, the output will be one-eighth (one-half times one-half times one-half). Companies planning an industrial wind farm install a metrological tower(s) or sonic wind profiler(s), and then record the wind speed and direction every 10 minutes for at least a year before deciding that a location that looks good on paper really is good. There is software that can estimate a location’s wind resource, but it’s just that, an estimate. The 120’ tower is excellent. For comparison, this tower is three and a half times the 35’ height of the wind turbine tower at the San Andres National Wildlife Refuge office outside Las Cruces on Hwy 70 near Brahman Rd. (Another government wind and solar facility which does not publish its production numbers.)
So, did the Santa Fe County Commissioners exercise proper due diligence in the use of County funds when they authorized the $75,000 cost, or were they so enamored with being “green” that they ended up wasting money? Why does a person have to explicitly ask about the wind turbine or (solar PV array) output at government installation, instead of having the current and historical output displayed on a website for all to see? After all, this complex was built to LEED Platinum status, partially to demonstrate Santa Fe County’s leadership in “green” building. Is the wind turbine meeting the goal of producing 3-6.8% of the facility’s electricity?
Regarding Ms Vigil’s obvious enchantment with this wind turbine and “green energy” in general, Ms. Vigil has an “out”. She is a lawyer, with a BA in Speech & Secondary Education (1973) and a MA in Education and Poli Sci (1983), so she can’t be expected to understand engineering and cost-benefit analysis. Except that as a Santa Fe County Commissioner for over eight years, her duties included protecting the tax dollars, as stated in the resume on her PRC candidacy website. Did Ms. Vigil let her desire to be “green” come before protecting the taxpayer’s greenbacks? Would she be an honest, independent member of the PRC, or an elected pawn of the Sierra Club? Does she know enough to ask the “right questions”, and then filter out the BS when someone provides a “Gish Gallop” answer?
