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  • From: Douglas Woodard <dwoodard@becon.org>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] new inventions
  • Date: Thu, 17 Jan 2008 02:19:12 -0500

A fundamental problem with the Darrieus rotor is that the forces on a blade reverse with each rotation, thus this design is especially vulnerable to materials fatigue.

Reliable startup requires a special provision such as a powered start or an attached Savonius rotor.

Aerodynamic braking (essential for safety) is extremely difficult with a Darrieus rotor.

Weak winds contain little energy. Power in the wind varies as the cube of the windspeed. The Darrieus design is difficult to mount high where the wind is strong. It fundamentally requires more materials for the power yield than a horizontal-axis design. There is no point in mounting a wind turbine low; it is not economical. It still has to be strong enough to survive storms. There is no point in a low-yield wind turbine which retains its fundamental problems of moving parts, rotation and vibration, and relatively high maintenance requirements. A photovoltaic system becomes preferable.

Darrieus wind turbines were tried on a fairly large scale in the early days of commercial wind turbines in California in the 1980s, but proved unable to compete economically with horizontal-axis deigns.

Doug Woodard
St. Catharines, Ontario, Canada



Lawrence F. London, Jr. wrote:

I have always been interested in possibilities with the Darrieus rotor.

"The wind energy system uses a Darrieus-type vertical axis wind turbine. It can operate normally even when the wind is not very strong."

Technology and materials available these days ought to b able to produce a
small high efficiency
Darrieus turbine for home electric power generation. Thses systems do not
have to be on a high tower,
can be light and mounted easilt alomst anywhere, i.e. safe and easy to
construct and install.




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