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1 <br /> Air Density Chanpe with Elevation height of the tower that you plan to <br /> 10'0°° use,and the frequency distribution of <br /> 9'0°° - the wind-an estimate of the number <br /> 8�000 .t.._. :ok." _ - = n ` ;.a � <br /> of hours that the wind will blow at <br /> � '�0°° each speed during an average yeaz. <br /> 0 6�D00 They should also adjust this calcula- <br /> F 5�0°° tion for the elevation of your site. <br /> -��' °�0°� Contact a wind turbine manufactumr <br /> s,000 or dealer for assistance with this <br /> 2�� � calculation. <br /> �'0°° � To get a preliminary estimate of the <br /> io �s ao as so ss �oo performance of a particulaz wind tur- <br /> Density change compared to sea level,9'o bine,use the forntula below. <br /> AEO=0.01328 Dz V3 <br /> So,the larger the rotor,the more Where: <br /> energy it can capture.The air density, � = p�ual energy output, <br /> p,changes slighdy with air tempera- kWh/yeaz <br /> ture and with elevation.The ratings <br /> for wind turbines are based on D = Rotor diameter,feet <br /> standazd mnditions of 59°F(15°C) V = �ual average wind speed, <br /> at sea level.A density correction mph <br /> should be made for higher elevations The Wind Energy Payback Period <br /> as shown in the Air Density Change Workbook found at www.nrel.gov/ <br /> with Elevation graph.A correction for �d/docs/spread_sheet_Final.xls is <br /> temperature is typically not needed a spreadsheet tool that can help you <br /> for predicting the long-term perfor- �Y��e economics of a small wind <br /> mance of a wind turbine. electric system and decide whether <br /> wind energy will work for you.The <br /> Although the calculation of wind spreadsheet can be opened using <br /> power illustrates important features Microsoft Exce195 software.It asks <br /> about wind turbines,the best mea- you to provide information about how <br /> sure of wind turbine performance is you're going to finance the system, <br /> annual energy output.The difference �e chazacteristics of your site,and <br /> between power and energy is that �e P�l�rnes of the system you're <br /> power(kilowatts[kW])is the rate at CO�idering.It then provides you with <br /> a simple payback estimation in years. <br /> which electriaty is rnnsumed,while �it takes too long to regain your capi- <br /> energy(kilowatt-hours[kWh])is the tal investment the number of years <br /> quantity rnnsumed.An estimate of comes too close or is greater than the <br /> the annual energy output from your life of the system—wind energy will <br /> wind turbine,kWh/yeaz,is the best not be practical for you. <br /> way to determine whether a particulaz <br /> wind turbine and tower will produce <br /> enough electricity to meet your needs. <br /> A wind turbine manufacturer can help <br /> you estimate the energy production <br /> you can expect.They will use a cal- <br /> culation based on the particular wind <br /> turbine power curve,the average <br /> annuai wind speed at your site,the <br />