Small Scale Wind Turbines at Williams College

Transcription

1 Augenbraun 1 JJ Augenbraun Geosciences 206 Professor Dethier and Ms. Boyd May 13, 2009 Small Scale Wind Turbines at Williams College Figure 1. Rendering of Morley Science Center with an ARE 442 wind turbine installed.

2 Augenbraun 2 Introduction As of 2007, the world population consumes approximately 400 quadrillion British Thermal Units (Btu) per year. Despite having only roughly 6% of the world population, the United States uses about 25% of the world s energy resources, consuming approximately quadrillion Btu per year. In the United States, this energy comes from a variety of sources including petroleum, natural gas, nuclear electric power, coal, and renewable energy sources. Renewable energy accounts for about 7% of total energy consumption in the United States. Of that 7%, only 5% comes from wind energy (Figure 2, Renewable Energy Trends, 2009). However, wind energy is currently the fastest growing renewable energy source in terms of installed capacity. In 2008, the wind industry added over 8,000 MW of capacity throughout the world, while in the United States 40% of new electric generation capacity came in the form of wind energy. Figure 2. The role of renewable energy consumption in the United States energy supply for Although the majority of wind capacity comes from industrially scale wind projects, the United States market for small wind turbines, defined as turbines with a capacity of 100 kw or

3 Augenbraun 3 less, grew rapidly in In 2008, the installation of more than 10,000 small wind turbines resulted in an addition of over 17 MW of domestic generation capacity and a 78% growth rate over the previous year. The small wind industry foresees thirty-fold growth over the next five years with an estimated total United States installed capacity jumping from the current 80 MW to 1,700 MW by 2014 (Stimmel, 2009). Many of these small wind turbines are being installed in residential settings, but some larger institutions are also experimenting with using wind energy from small wind turbines. For example, Yale University recently installed ten 1 kw wind turbines on the University s engineering building (Figure 3). These wind turbines built by AeroVironment can produce electricity in wind speeds as low as 3.1 m/s ( Micro-Wind, 2009). Figure 3. The micro-wind turbines at Yale University. Figure 4. The 10 kw turbine at the University of Vermont. In 2005, the University of Vermont installed a 10 kw wind turbine as part of the Vermont Department of Public Service Wind Development Program (Figure 4). At the time of installation, the wind turbine was expected to generate approximately 3,000-5,000 kwh of electricity per year (Wakefield, 2005). In addition, Middlebury College installed an identical 10 kw wind turbine under the same Vermont program. At Middlebury College, the wind turbine has been providing approximately 25% of the electricity used at the College s recycling facility ( Wind Power ). As

4 Augenbraun 4 these installations demonstrate, under the proper circumstances, installing a wind turbine in a college setting is definitely possible and feasible. Even though small scale wind energy constitutes such a small total installed capacity, it is still equivalent to removing 13,300 cars from the roads or displacing 76,000 tons of carbon dioxide per year. Once installed, a wind turbine produces no greenhouse gas emissions except those associated with the occasional maintenance and repair requirements of the turbine (Stimmel, 2009). Situated in the proper windy location, a wind turbine can provide clean, zeroemission electricity. In 2007, Williams College adopted a goal to reduce greenhouse gas emissions by 10% below the College s levels by 2020 (Schapiro, 2007). In light of this goal and the clean nature of wind energy, this report explores the possibility of employing small scale wind turbines at Williams College to reduce the College s dependency on fossil fuels for daily electricity consumption. Local wind data will be analyzed to determine the practicality of installing small wind turbines on College owned buildings and property. Data Overview Data were collected by an anemometer located in the northwest corner of the top of Morley Science Center between November 25, 2003 and November 24, 2004 (Figure 5). Measurements were taken from an anemometer Figure 5. The installation of the meteorological tower in late at a height of 4.27 meters above the roof s surface. The meteorological tower supported several anemometers and weathervanes, so data were used from the highest anemometer to reduce the

5 Augenbraun 5 error of estimating winds at greater heights. A typical small wind turbine is mounted on a tower that allows it to operate at heights in excess of 4.27 meters. Therefore, part of this report focuses on estimating the wind speeds at common tower heights such as 5, 10, 15, and 25 meters. Data Analysis Data were collected every ten minutes and then averaged to obtain daily averages for the 366 days of the measurement period. I used the daily averages to estimate wind speeds at heights of 5, 10, 15, and 25 meters above the surface of the roof. Estimates are based on the following wind shear formula ( Roughness and Wind Shear, 2003): v = v ref * ln ( z / z o ) / ln ( z ref / z o ) (1) In this formula, v is the wind speed estimate at a height z meters above ground level. v ref is the known wind speed at a known height z ref. Finally, z o is the roughness length in the current wind direction. For the roof of Morley Science Center, I used a roughness length of 0.40 meters based on the definition of rough and uneven terrain provided in the Danish Wind Industry Association s reference manual ( Wind Energy Reference, 2003). Since we have wind speed data at 4.27 meters, these values were inputted into Equation 1 to estimate the wind speed at the desired height of 5, 10, 15, or 25 meters. For example, using the daily average wind speed on November 25, 2003 of 1.8 m/s results in the following calculation for the wind speed at 25 meters: v = 1.75 m/s * ln ( 25 m / 0.40 m ) / ln ( 4.27 m / 0.40 m ) = 3.06 m/s (2) The rest of the estimated wind speeds were calculated in a similar manner (Appendix A). Table 1 summarizes the yearly averages, minimums, and maximums of the various height estimates.

6 Augenbraun 6 Table 1. Yearly averages, minimums and maximums at different heights above roof. Minimum Daily Average (m/s) Maximum Daily Average (m/s) Yearly Average (m/s) 5 Meters 10 Meters 15 Meters 25 Meters After estimating the wind speeds at various heights, I sorted the wind speeds from lowest to highest. After sorting, I grouped the wind speeds by 0.50 m/s increments (Table 2). Table 2. Frequency of wind speeds in 0.50 m/s increments at various heights. Daily Avg. Wind Speed 5 meters 10 Meters 15 Meters 25 Meters (m/s)

7 Augenbraun 7 I then plotted this data on a graph that shows how wind speed increases with height (Figure 6). As expected, higher frequencies of higher daily average wind speeds are observed at higher heights. Figure 6. A graph of daily average wind speeds grouped by 0.50 m/s intervals. As the height increases, so does the frequency of higher daily average wind speeds. Once I grouped the wind speeds, I used these groupings to calculate potential power production of a wind turbine on the roof of Morley Science Center. I used power curves from the various turbine manufacturers to calculate the expected yearly energy production of the wind turbines examined in this study. By comparing the number of days at a certain wind speed interval (usually 0.50 or 1.0 m/s intervals) with the power produced at that speed, daily and yearly energy production can be estimated. The electricity production calculations for the Eoltec Scirocco serve as a good example of this process. Eoltec provides a detailed power curve for the Scirocco making it relatively easy to estimate the energy produced (Figure 7). Along with a power curve, the manufacturer provides a table of the electricity production at various wind speeds in 1.0 m/s ranges (Table 3, Eoltec

8 Augenbraun 8 Scirocco, 2009). Therefore, I grouped the data for each wind speed into 1.0 m/s intervals starting at 2.5 to 3.5 m/s (note: a wind speed of 3.50 m/s is counted in the 3.5 to 4.5 m/s interval). Any measurements less than 2.5 m/s are below the turbine s cutoff speed so no electricity would be produced. After determining the number of days in each group of wind Figure 7. The power curve of the Eoltec Scirocco wind turbine. speeds, I multiplied that number by 24 to convert to hours. I then multiplied the number of hours by the predicted power production of the corresponding bracket of wind speeds to get kilowatthours of electricity. Summing the kilowatt-hours gave the total electricity produced for the year (Table 3). Table 3. Calculation of yearly energy production of the Eoltec Scirocco. Wind Speed (m/s) Power (kw) Days Hours kwh Total days 213 Total kwh Produced Overall, there were 213 days with high enough wind speed averages to produce some electricity. These 213 days resulted in the production of approximately 2750 kwh of electricity.

9 Augenbraun 9 Assessing the Validity of Using Daily Averages Since wind power is related to the cube of the wind speed, a small variation in wind speed can have a large effect on power. Because of this relationship, the smaller the time interval over which the average wind speed is calculated, the more accurate the final electricity production estimates. Therefore, I decided to assess the validity of my estimates by comparing the energy production between April 21, 2004 and April 27, 2004 based on daily averages to an estimate based on the ten minute average wind speed. To perform this comparison, I used estimated wind speed at the 15 meter height with the Eoltec Scirocco s power curve (Appendix B). Using the same techniques to estimate the energy production as explained in the previous section, I found that the daily averages gave an estimate of 49 kwh (Table 4) while the ten minute averages gave an estimate of 128 kwh (Table 5). Table 4. Calculation of energy production of the Eoltec Scirocco for the week of 4/21/2004 to 4/27/2004 using daily averages. Wind Speed (m/s) Power (kw) Days Hours kwh Total days 7 Total kwh Produced Table 5. Calculation of energy production of the Eoltec Scirocco for the week of 4/21/2004 to 4/27/2004 using ten minute averages. Wind Speed (m/s) Power (kw) 10 Minute Intervals Hours kwh Total days 213 Total kwh Produced

10 Augenbraun 10 As expected, the ten minute averages gave a significantly higher estimate of wind energy production than did the daily averages. This finding reinforces the importance of using as small intervals as possible for calculating the energy produced by a turbine. However, analyzing an entire year s worth of ten minute data in the manual manner described would be exceedingly time-consuming so I decided to continue using the daily averages due to practical considerations. If this week in April is any indication, the actual energy produced by a wind turbine would likely be two to three times higher than the amount calculated using daily averages. Wind Turbine Options Figure 9. The Windspire wind turbine, an example of vertical axis design. Small wind turbines are classified into three categories: micro, mini, and small. Micro wind turbines have blade diameters of about 0.50 to 1.25 meters. Mini turbines have blade diameters of 1.25 to 2.75 meters, and small wind turbines have blade diameters of 2.75 to 8.00 meters (Gipe, 2004). Since energy production is directly related to blade diameter (along with many other factors Figure 8. The Eoltec Scirocco wind turbine, an example of including location, height, and turbine efficiency), longer the HAWT design. blades generally produce more electricity. There are numerous varieties of small wind turbines on the market. Most turbines are of the horizontal axis wind turbine (HAWT) design (Figure 8). An alternative design, vertical axis wind turbines (Figure 9), was heavily studied in the 1970s and 1980s but could never produce electricity as cost-effectively as could HAWTs. The basic technology behind wind turbines has not changed much since the late 1970s, but efficiency, reliability, noise production, and cost effectiveness have vastly

11 Augenbraun 11 improved. Modern wind turbines last longer, produce more electricity, and generate less noise than older models (Manwell, McGowan, and Rogers, 2002). I explored a wide variety of wind turbines for this project. A main criterion during my investigation was to find wind turbines with low cut-in speeds. A low-cut in speed is essential so the wind turbine can take advantage of the generally low wind speeds in the Purple Valley. I eventually settled on six possible options: the Eoltec Scirocco ( Eoltec Scirocco, 2009), the ARE 110 and ARE 442 ( ARE Wind, 2008), the Bergey Excel-S ( Bergey, 2009), the ReDriven FD ( ReDriven, 2008), and the Windspire ( Windspire, 2009). All of these wind turbines (except the Windspire) have cut-in speeds of approximately 2.0 to 3.0 m/s. In addition, all of these turbines are relatively light and can be roof-mounted on most existing structures. Furthermore, these wind turbines can connect directly into a building s electricity supply to avoid the issue of having to store the power in batteries. I projected annual electricity production at 15 meters (a common height for small wind turbines) above the roof for these six devices based on the manufacturers power curves (Appendix B). In some cases, a detailed power curve was not available so monthly estimated production figures based on different wind speeds were used. A summary of the key statistics for each turbine is presented in Table 6. Table 6. Summary of six wind turbines and their projected annual electricity production at a height of 15 meters above the roof of the Morley Science Center. Device Eoltec Scirocco ARE 110 ARE 442 Bergey Excel-S Windspire ReDriven FD Type Horizontal (2 blades) Horizontal (3 blades) Horizontal (3 blades) Horizontal (3 blades) Vertical axis Horizontal (3 blades) Cut-in speed 2.7 m/s 2.5 m/s 2.5 m/s 3.1 m/s 4.0 m/s 2.0 m/s Rotor diameter 5.6 m 3.6 m 7.2 m 6.7 m.6 m Not listed Weight (with tower) 202 kg 143 kg 612 kg 1400 kg 283 kg Not listed

12 Augenbraun 12 Projected annual electricity at 15 m 2746 kwh 1380 kwh 7800 kwh 2880 kwh 300 kwh 3651 kwh Rated Power 6 kw at 11.5 m/s 2.5 kw at 11 m/s 10 kw at 10 m/s 10 kw at 13.8 m/s 1.2 kw at 5.4 m/s 5 kw at 10 m/s In general, the estimates did not come close to the expected annual electricity production based on the rated power of the turbines. This result was expected because the rated powers are for wind speeds much higher than the averages recorded on the roof of Morley Science Center. Most wind turbines do not produce much electricity at low wind speeds and this drawback is reflected in the projected electricity amounts. The ARE 442 and the ReDriven FD turbines had the two highest net capacity factors of about 8.5% each. It is interesting to note that this is approximately the same factor as that of the solar panels on the roof of Morley Science Center (Johns, 2008). Based on this information, the ReDriven and ARE 442 turbines appear to be the most suitable turbines for the College to consider installing. Although the previously discussed wind turbines are all from the small wind category of small wind turbines, the College recently installed some MotorWind micro-wind category turbines on the heating plant. MotorWave produces these MotorWind turbines that can be installed in large arrays that will start producing electricity in 1.0 m/s winds (Figure 10). Unfortunately, each turbine does not produce much electricity with a set of sixty producing about 0.72 kwh over a whole day Figure 10. An array of MotorWind turbines. in 4.0 m/s winds. In addition, some sort of battery system is required to store the electricity produced as it cannot be directly fed into the building s electrical grid. Furthermore, the company recommends winds of at least 4.0 m/s to make the turbines economically viable ( Motorwind, 2009). Although the turbines are relatively inexpensive, they do not make sense for Williams College to install on a larger scale than the few on the heating plant.

13 Augenbraun 13 Cost Analysis After calculating projected annual electricity production at 15 meters height, I calculated the price and payback periods. All calculations were based on a delivery cost of $0.13 per kilowatt-hour of electricity. Prices quoted include the turbine, tower, inverter, and wiring. To account for engineering and installation costs, I doubled the price calculated for the components based on an estimate suggested by the Director of the Zilkha Center for Environmental Initiatives, Ms. Stephanie Boyd. Dividing this cost by the total amount of money saved on electricity annually gave an estimated payback period (Table 7). Table 7. Costs of the wind turbines and estimated payback periods based on different scenarios. Rebates were calculated using the Massachusetts Technology Collaborative rebate calculator ( Commonwealth Wind, 2009). Device Eoltec Scirocco ARE 110 ARE 442 Bergey Excel-S Windspire ReDriven FD Projected annual electricity at 15 m Cost of Turbine and Parts 2746 kwh 1380 kwh 7800 kwh 2880 kwh 300 kwh 3651 kwh $35,000 $16,300 $43,250 $41,000 $6,500 $24,000 Total Installed Cost $70,000 $32,600 $86,500 $82,000 $13,000 $48,000 Total Payback 196 years 182 years 85 years 219 years 333 years 101 years Period Cost After Incentives $56,383 $25,965 $57,400 $67,740 N/A $33,448 Payback Period (with incentives) Payback Period (with 2.5 times electricity production and adjusted incentives) 158 years 145 years 56.5 years 181 years N/A 70.5 years 54 years 52 years 18 years 63 years N/A 23.5 years

14 Augenbraun 14 The total payback periods are extremely long, but do not take into account certain incentives and rebates available for small scale wind projects. The Micro Wind Initiative sponsored by the Massachusetts Technology Collaborative provides a hybrid rebate structure. The first part of the rebate is based on the system s rated capacity, while the second part of the rebate is based on the number of kilowatt-hours produced during the first year of operation ( Commonwealth Wind, 2009). The federal government also offers a tax credit for small wind projects worth 30% of the project s cost ( Federal Incentives, 2009). Unfortunately, since Williams College is a tax-exempt institution, this credit does not benefit the College. After factoring these incentives into the calculations, the payback periods become more reasonable. Payback periods are further reduced by assuming that 2.5 times more electricity will be produced than suggested by the daily averages based on the analysis using ten minute averages. Furthermore, since the installed cost is a rough estimate, actual payback periods may be shorter than indicated in the table. Increased electricity costs over the course of a turbine s service period make the return on investment even more attractive. Conclusions Wind power is a valuable source of energy, but turbines must be placed in appropriate sites to capture the maximum amount of energy possible. The Purple Valley is not very conducive to wind energy with its generally low average wind speeds throughout the year. However, certain small scale wind turbines do prove cost effective after taking into account incentives offered by the state of Massachusetts. Based on initial analysis of daily average wind speeds at a height of 15 meters above Morley Science Center s roof, wind turbines do not seem economically viable for Williams College. However, I still recommend the installation of either

15 Augenbraun 15 the ARE 442 or ReDriven 5 kw turbine on Morley Science Center. By taking into account the fact that daily averages vastly underestimate energy production (by an order of two to three times), the payback period of these two wind turbines drop into a much more reasonable range of about 20 years. These two types of turbines had the shortest payback periods while also having a good record of reliability. This approximately 20 year payback period is actually better than that of the solar panels that the College has previously installed. Since Williams College is a leading institution in the education field, it should also try to be a leader in sustainability. As such, the College should not evaluate the installation of a wind turbine from a purely economic point of view. The College should take into account the public relations boost as well as the reduction in greenhouse gas emissions associated with the installation of a wind turbine. A wind turbine can also provide valuable educational opportunities for students at the College. For example, reliable wind speed measurements and power production numbers can be recorded from a wind turbine on Morley Science Center. Other colleges across the country have undertaken wind turbine projects; it is now time for Williams College to install one of its own. Convincing the administration to install a wind turbine constitutes the largest hurdle of this project. Given the current economic situation and declining endowment, College administrators will likely be reluctant to fund a project with a twenty year payback horizon. Hopefully, the administration will eventually agree to such a project given the College s commitment to reducing carbon emissions and the reasons previously discussed. Once the College decides to install a wind turbine, going forward with the installation will be relatively straightforward. A structural engineering survey will be necessary to determine which roofs on campus can support the weight of a wind turbine. Then, the College will need to seek permits

16 Augenbraun 16 from Williamstown pursuant to Subsection G of Article 7 of the Williamstown Zoning Bylaws ( Zoning Bylaws, 2008). Finally, a contractor (or possibly members of the College s Facilities department) will be used to install the wind turbine. Once monitoring equipment and wiring are installed, the turbine will be ready to produce energy. This report focused on the roof of Morley Science Center because data was collected on that roof. Morley Science Center s roof is approximately the same height as many other flat roofs on campus. Therefore, we can reasonably assume that similar wind conditions exist above the roofs of such buildings as the Paresky Center, buildings in the Greylock Quad, and Sawyer Library. As a result, a small wind turbine could be added to the top of any of these buildings and be expected to have a payback period similar to one installed on Morley Science Center. Any of these buildings would serve as good candidates for a wind turbine, but Thompson Chapel would truly be the best candidate. The top of the Chapel is several stories taller than any surrounding buildings and well above any turbulence created by surrounding trees. A wind turbine on top of the Chapel would likely experience much higher winds than those recorded on Morley Science Center. In addition, a turbine on the top of the Chapel would have much greater visibility and send a strong message about the College s commitment to sustainability. Overall, I strongly recommend the installation of a small wind turbine, specifically an ARE 442 or ReDriven FD , on a campus building. The ideal location would be on top of Thompson Chapel, but a more realistic location would be the roof of Morley Science Center or Paresky Center. Given the estimated wind speeds and some reasonable assumptions, the College can expect to regain its investment in approximately 20 to 25 years. In addition, installing a small scale wind turbine on the campus could provide the motivation for eventually developing a large

17 Augenbraun 17 scale wind project on Berlin Mountain. It is time for Williams College to start capturing the energy of the wind. Works Cited ARE Wind Turbines. Abundant Renewable Energy Abundant Renewable Energy, LLC. 19 May < Bergey Small Wind Turbines. Bergey Windpower Co Bergey Windpower Co. 19 May < Commonwealth Wind Incentive Program. Massachusetts Technology Collaborative Massachusetts Technology Collaborative. 16 May < renewableenergy/commonwealth_wind/micro_wind.html>. Eoltec Scirocco. Solacity Inc Solacity Inc. 18 May < Scirocco.htm>. Federal Incentives/Policies for Renewables and Efficiency. Database of State Incentives for Renewables and Efficiency. 19 February N.C. State University. 18 May < Gipe, Paul. Wind Power: Renewable Energy for Home, Farm, and Business. White River Junction, VT: Chelsea Green Publishing Company, Johns, Amy. Solar Electricity: Our Installations. Sustainability at Williams Williams College. 18 May < solar/solar.php>. Manwell, J.F., McGowan, J.G., and A.L. Rogers. Wind Energy Explained: Theory, Design and Application. West Sussex, England: John Wiley & Sons Ltd, Micro-Wind at the Becton Center. Yale Office of Sustainability Yale University. 16 May < MotorWind. MotorWave. 21 April MotorWave Ltd. 19 May < ReDriven 5kW Turbine. ReDriven: Eco-Friendly Power ReDriven Power Inc. 19 May

18 Augenbraun < Renewable Energy Trends in Consumption and Electricity: 2007 Edition. Energy Information Administration: Official Energy Statistics from the U.S. Government. April U.S. Department of Energy. 16 May < page/trends/rentrends.html>. Roughness and Wind Shear. Danish Wind Industry Association. 1 June Danish Wind Industry Association. 18 May < Schapiro, Morton. Letters from the President and Trustees. Williams College. 24 January Williams College. 16 May < president/letters/070124_cac.php>. Stimmel, Ron. AWEA Small Wind Turbine Global Market Study: Year Ending Small Wind American Wind Energy Association. 16 May < smallwind/pdf/09_awea_small_wind_global_market_study.pdf>. Wakefield, Jeffrey. New UVM Wind Turbine to Serve Educational, Research Purposes. University Communications: University of Vermont. 7 October University of Vermont. 16 May < Wind Energy Reference Manual Part 1: Wind Energy Concepts. Danish Wind Industry Association. 1 June Danish Wind Industry Association. 18 May < Wind Power. Middlebury: Sustainability Integration Office. Middlebury College. 16 May < energy/wind+power+at+recycling+center.htm>. Windspire. Windspire Turbine Mariah Power. 18 May < windspire-overview.aspx>. Zoning Bylaws: Town of Williamstown, MA. Code of Williamstown. 20 May Town of Williamstown. 17 May <

19 Augenbraun 19 Image Credits Figure 2: The Role of Renewable Energy Consumption in the Nation s Energy Supply. Energy Information Administration: Official Energy Statistics from the U.S. Government. April U.S. Department of Energy. 18 May < solar.renewables/page/trends/highlight1.html>. Figure 3: Micro-Wind at the Becton Center. Yale Office of Sustainability Yale University. 16 May < Figure 4: Wakefield, Jeffrey. New UVM Wind Turbine to Serve Educational, Research Purposes. University Communications: University of Vermont. 7 October University of Vermont. 16 May < Figure 5: Image provided by Professor David Dethier of Williams College Geosciences Department. Figures 7 and 8: Eoltec Scirocco. Solacity Inc Solacity Inc. 18 May < Scirocco.htm>. Figure 9: Windspire. Windspire Turbine Mariah Power. 18 May < windspire-overview.aspx>. Figure 10: MotorWind. MotorWave. 21 April MotorWave Ltd. 19 May < Figure B1: Eoltec Scirocco. Solacity Inc Solacity Inc. 18 May < Scirocco.htm>. Figure B2: Bergey Small Wind Turbines. Bergey Windpower Co Bergey Windpower Co. 19 May <

20 Augenbraun 20 Figure B3: ARE Wind Turbines. Abundant Renewable Energy Abundant Renewable Energy, LLC. 19 May < Figure B4: ReDriven 5kW Turbine. ReDriven: Eco-Friendly Power ReDriven Power Inc. 19 May < Figure B5: Windspire. Windspire Turbine Mariah Power. 18 May < windspire-overview.aspx>. Appendix A: Recorded and Estimated Wind Speeds on top of Morley Science Center Date Anem 1 Day Avg Wind Speed (m/s) Est. Speed at 5 m Est. Speed at 10 m Est. Speed at 15 m Est. Speed at 25 m Date Anem 1 Day Avg Wind Speed (m/s) Est. Speed at 5 m Est. Speed at 10 m Est. Speed at 15 m Est. Speed at 25 m 11/25/ /26/ /26/ /27/ /27/ /28/ /28/ /29/ /29/ /30/ /30/ /31/ /1/ /1/ /2/ /2/ /3/ /3/ /4/ /4/ /5/ /5/ /6/ /6/ /7/ /7/ /8/ /8/ /9/ /9/ /10/ /10/ /11/ /11/ /12/ /12/ /13/ /13/ /14/ /14/ /15/ /15/ /16/ /16/ /17/ /17/ /18/ /18/ /19/ /19/ /20/ /20/ /21/ /21/ /22/ /22/ /23/ /23/ /24/ /24/ /25/ /25/ /26/ /26/ /27/ /27/ /28/ /28/ /29/ /29/ /30/ /30/ /31/ /1/ /1/ /2/

21 Augenbraun 21 1/2/ /3/ /3/ /4/ /4/ /5/ /5/ /6/ /6/ /7/ /7/ /8/ /8/ /9/ /9/ /10/ /10/ /11/ /11/ /12/ /12/ /13/ /13/ /14/ /14/ /15/ /15/ /16/ /16/ /17/ /17/ /18/ /18/ /19/ /19/ /20/ /20/ /21/ /21/ /22/ /22/ /23/ /23/ /24/ /24/ /25/ /25/ /26/ /26/ /27/ /27/ /28/ /28/ /29/ /29/ /30/ /30/ /31/ /31/ /1/ /1/ /2/ /2/ /3/ /3/ /4/ /4/ /5/ /5/ /6/ /6/ /7/ /7/ /8/ /8/ /9/ /9/ /10/ /10/ /11/ /11/ /12/ /12/ /13/ /13/ /14/ /14/ /15/ /15/ /16/ /16/ /17/ /17/ /18/ /18/ /19/ /19/ /20/ /20/ /21/ /21/ /22/ /22/ /23/ /23/ /24/ /24/ /25/ /25/ /26/ /26/ /27/ /27/ /28/ /28/ /29/

22 Augenbraun 22 2/29/ /30/ /1/ /31/ /2/ /1/ /3/ /2/ /4/ /3/ /5/ /4/ /6/ /5/ /7/ /6/ /8/ /7/ /9/ /8/ /10/ /9/ /11/ /10/ /12/ /11/ /13/ /12/ /14/ /13/ /15/ /14/ /16/ /15/ /17/ /16/ /18/ /17/ /19/ /18/ /20/ /19/ /21/ /20/ /22/ /21/ /23/ /22/ /24/ /23/ /25/ /24/ /26/ /25/ /27/ /26/ /28/ /27/ /29/ /28/ /30/ /29/ /31/ /30/ /1/ /1/ /2/ /2/ /3/ /3/ /4/ /4/ /5/ /5/ /6/ /6/ /7/ /7/ /8/ /8/ /9/ /9/ /10/ /10/ /11/ /11/ /12/ /12/ /13/ /13/ /14/ /14/ /15/ /15/ /16/ /16/ /17/ /17/ /18/ /18/ /19/ /19/ /20/ /20/ /21/ /21/ /22/ /22/ /23/ /23/ /24/ /24/ /25/ /25/ /26/ /26/

23 Augenbraun 23 4/27/ /27/ /28/ /28/ /29/ /29/ /30/ /30/ /1/ /31/ /2/ /1/ /3/ /2/ /4/ /3/ /5/ /4/ /6/ /5/ /7/ /6/ /8/ /7/ /9/ /8/ /10/ /9/ /11/ /10/ /12/ /11/ /13/ /12/ /14/ /13/ /15/ /14/ /16/ /15/ /17/ /16/ /18/ /17/ /19/ /18/ /20/ /19/ /21/ /20/ /22/ /21/ /23/ /22/ /24/ /23/ /25/ /24/

24 Augenbraun 24 Appendix B: Wind Turbine Power Curves Figure B1. The power curve of the Eoltec Scirocco wind turbine.

25 Augenbraun 25 Figure B2. The power curve of the Bergey Excel-S wind turbine. Figure B3. The power curves of the ARE 110 and ARE 442.

26 Augenbraun 26 Figure B4. The power curve of the ReDriven 5kW turbine. Figure B5. The power curve of the Windspire.

27 Augenbraun 27