{"id":236,"date":"2004-05-09T21:33:15","date_gmt":"2004-05-10T01:33:15","guid":{"rendered":"http:\/\/scruss.com\/blog\/?p=236"},"modified":"2007-05-26T09:38:25","modified_gmt":"2007-05-26T13:38:25","slug":"windsave-again","status":"publish","type":"post","link":"https:\/\/scruss.com\/blog\/2004\/05\/09\/windsave-again\/","title":{"rendered":"Windsave, again"},"content":{"rendered":"<p>Anent <a href=\"http:\/\/scruss.com\/blog\/archives\/000031.html\">my previous rant about Windsave claiming impossible efficiencies<\/a>, they&#8217;ve made some changes to their website. The machines now have larger diameters (1250 and 1750 mm \u00e2\u20ac\u201d up from 1000 and 1400mm), and much lower rated power (500W and 1000W at 27mph \u00e2\u20ac\u201d down from 750 and 1200).<\/p>\n<p>Plugging in those numbers to C<sub>p<\/sub> = P \/ ( 0.48106 d<sup>2<\/sup> v<sup>3<\/sup> ), we get more realistic efficiencies of 0.378 and 0.386 (for the small and large machines, respectively).<\/p>\n<p>The <a href=\"http:\/\/truenorthpower.com\/products_turbines.htm\">Lakota<\/a> turbine we installed last week has a nominal rated power of 900W at 28.8 mph for a 2.09m diameter rotor. It has a very conservative C<sub>p<\/sub> = 0.20, although David Cooke says that typically they see 1,000 Watts at around 25mph (a C<sub>p<\/sub> of around 0.34).<\/p>\n<p>At the other end of the scale, the <a href=\"http:\/\/awe-wind.com\/lw52\/\">Lagerwey LW52<\/a> is a 51.5m diameter machine rated at 750kW at 12ms<sup>-1<\/sup>. This advanced utility scale, variable pitch machine has a C<sub>p<\/sub> = 0.34.<\/p>\n<p>Windsave&#8217;s revised figures are much more credible, but until we have real figures backed by a few years of installations, there&#8217;s little more we can say about them. I&#8217;m a little concerned that, although there are claims that 1000s of these machines have been sold, there&#8217;s not a single real photo of one on the web.<\/p>\n<p>I&#8217;m going to enjoy putting up an anemometer and logging system alongside the <a href=\"http:\/\/wearcam.org\/urbine\/\">urbine<\/a> downtown. We&#8217;ll see how it runs.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Anent my previous rant about Windsave claiming impossible efficiencies, they&#8217;ve made some changes to their website. The machines now have larger diameters (1250 and 1750 mm \u00e2\u20ac\u201d up from 1000 and 1400mm), and much lower rated power (500W and 1000W at 27mph \u00e2\u20ac\u201d down from 750 and 1200). Plugging in those numbers to Cp = [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[8],"tags":[57,58,61,62,60,59,56],"class_list":["post-236","post","type-post","status-publish","format-standard","hentry","category-wind-things","tag-betz","tag-lagerwey","tag-lakota","tag-rant","tag-urbine","tag-wind","tag-windsave"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pQNZZ-3O","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/posts\/236","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/comments?post=236"}],"version-history":[{"count":0,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/posts\/236\/revisions"}],"wp:attachment":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/media?parent=236"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/categories?post=236"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/tags?post=236"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}