Article 138277 of alt.energy.homepower: Path: news.misty.com!not-for-mail From: nicksanspam@ece.villanova.edu Newsgroups: alt.energy.homepower Subject: Re: Vertical axis windmill prices Date: 12 Jun 2008 11:48:33 -0400 Organization: Villanova University Lines: 33 Message-ID: References: NNTP-Posting-Host: acadia.ece.villanova.edu X-Trace: max.inside.misty.com 1213282040 15941 153.104.44.130 (12 Jun 2008 14:47:20 GMT) X-Complaints-To: abuse@misty.com NNTP-Posting-Date: Thu, 12 Jun 2008 14:47:20 +0000 (UTC) Xref: news.misty.com alt.energy.homepower:138277 The Master wrote: >Does anyone by chance have a price, or know of a place selling them that >actually tells you the price up front, for a vertical axis windmill large >enough to power a 2,000 square foot grid connected home in a 10 MPH >average wind? An average US house uses about 800 kWh/mo, about 1100 watts on a continuous basis, and page 36 of Paul Gipe's 1993 Wind Power book says the wind power density with a Rayleigh speed distribution is 0.104V^3 W/m^2, where V is the average windspeed in mph and the best rotors achieve 40% efficiency (vs the 60% Betz limit)... 90% efficiencies for the transmission, generator, and power conversion make the wind power density 0.0303V^3 W/m^2, or 30.3 W/m^2 at 10 mph, so you might have 1100/30.3 = 36 m^2 of swept area, eg a 22 foot diameter circular windmill, comparable to the size of the house. I don't know where to buy one of these, but you might make a high-speed, 6-blade double-delta Darrieus rotor with 2 tetrahedra joined on a horizontal face, rotating on 2 points, with an automobile wheel at the top and another at the bottom, attached to a 5:1 step-up auto rear with the spider gears welded together, with more stepup for an induction motor that could act as a motor to start the rotor. It might have 6 galvanized steel tubes and 6 thin, low-solidity dacron sailcloth sailblades with the leading edges wrapped around the tubes and trailing edges attached to 6 wires. A tension ring with 3 horizontal wires could connect 3 points halfway up to give the windmill vertical support, and 3 guy wires could hold down a pillow hlock at the top. Good luck :-) Nick