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For a 10kW residential -scale turbine <br />dower <br />Wir�d kVJhjyear <br />SysteiTa <br />3acrQmentai: <br />Incremental iiacremeratal'..; <br />7�eight <br />Abed <br />cast <br />sosl irAm <br />energy <br />anergy <br />0h I:.6fl <br />autputf�am <br />ir�cremenial. <br />- <br />&X <br />60 <br />7.3 <br />2,709 <br />$48,665 <br />--- <br />--- <br />8D <br />9.3 <br />6,136 <br />$49,841 <br />$1176 or <br />2260/6 <br />2260/.> 2.40/6 <br />2.4% <br />= 94 to 1 ROI <br />100 <br />10.7 <br />9,338 <br />$51y346 <br />$2681 or <br />3440% <br />3440/.-- 5.50/b <br />5.5% <br />= 63 to 1 ROI <br />* = Return on InvestmenthAick5agrillo,AwEAlMndletter,January 2006 <br />Overly conservative zoning height <br />restrictions therefore cost the owner <br />money - and a lot of it. They can also <br />mean more sound, since taller towers <br />raise the generator high above the <br />ground, diluting sound. considerably. <br />Sound decreases four -fold with every <br />doubling of distance from the turbine <br />(including distance above the ground) so <br />taller towers are better for their owners as <br />well as neighbors. (See also `.'Sound" p. 11.) <br />For zoning officials, the importance <br />of strong winds also means that tower <br />height cannot be compromised as a <br />gesture to neighbors concerned about <br />the visibility of the turbine. "Hiding" a <br />turbine from neighbors using a shorter <br />tower almost always means hiding it <br />from the wind, too, <br />Nor do two shorter installations make an <br />acceptable substitute for a single, taller <br />one. A tower alone can comprise 5011/o or <br />more.of a system's total cost, so multiple, <br />shorter turbines (on multiple towers) cost <br />the owner far more than a single, taller <br />system, (See also "Multiple Turbines," p. 14.) <br />It is also important to keep in mind <br />that a turbine's generator size <br />(generating capacity, measured in <br />kilowatts or kW) has little, if anything, <br />to do with its tower height. Sometimes <br />zoning regulations mistakenly limit <br />tower heights based on the size of <br />the turbine's capacity, thinking that <br />a 2kW turbine, for example, always <br />corresponds to a 40 foot tower. This is <br />not the case. Appropriate tower height <br />is matched to a turbine depending on <br />surrounding terrain, trees and buildings, <br />and wind resource. Therefore, tower <br />height restrictions, if any, should only <br />reflect sound and safety concerns rather <br />than be designed to correspond to a <br />system's generating capacity. Most <br />often, in fact, established sound and <br />setback requirements negate the need <br />even to mention height in regulations <br />for small wind systems. _ <br />Mariah Power Windspire <br />IkW turbine <br />Bergey WindPower <br />10kW XLS turbine <br />