I Built a Wind Charger for $400!

Enlarge Image Image Gallery Raising the assembled tower, generator, and propeller of the wind charger. PHOTO: MOTHER EARTH NEWS STAFF

SPECIAL NOTE: The folks who put up the windmill tower were part of a wedding party! John and O'Malley Stouman (the people who own the land on which the wind engine is erected) were married the day before the unit went up... and everyone who came to the wedding helped assemble the dome and install the generator. The bride herself christened the power rig the "Sencenbaugh O₂ Powered Delight".

Intrigued—as many folks are nowadays—by the idea of free, nonpolluting electrical energy, I set about constructing (with a little help from my friends) a wind charger of my own design. The research, planning, blueprinting, and building consumed a little over a year's worth of spare time . . . but the months of work seemed well worth the investment the first evening we enjoyed stereo music and fluorescent lighting powered by our self-contained system.

The total cost of my home-built unit was a little over $400 and—now that I've pioneered the design—I'm sure you can duplicate the rig for from $300 to $350, depending on your choice of batteries. I'm also reasonably confident that you should be able to construct a wind charger like mine in any ordinary home woodworking shop. Everything but the blades can be made with hand tools and an electric drill. If you're exceedingly clever and determined, I suppose you might even fabricate the propeller with a 14" band saw and hand sand them . . . but I recommend that you figure on using a tilting table saw and belt sander for building the three airfoils.

My complete wind-driven electrical system consists of five main parts: [1] the fan, which is rotated by the wind and which—in turn—drives [2] the unit that generates direct current, [3] a tower that supports the first two components, [4] batteries and [5] an inverter that changes the direct current to alternating current.

The Rotor Assembly

The fan on my wind charger is a wooden, three-bladed variable pitch (constant speed) propeller ten feet in diameter. The prop is made of clear white pine and is sealed and protected by an epoxy resin compound called Envirotex.

I chose the three-blade design because my research indicated that such an arrangement provides the best balance and highest efficiency. The "Clark Y" airfoil that I used was picked because it gives high lift at low speeds.

For optimum efficiency, it's quite important that a windmill's entire prop-rotor assembly be very carefully balanced so that all loads are equally distributed along the blades at high speeds. Otherwise the rotor vibrates as it turns, performance falls drastically, and the whole unit can be endangered.