Wednesday, June 3, 2009

Wind energy isn't just spinning propellors any more

Among the primary concerns about wind energy: the appearance of giant towers with massive spinning blades; and the risk that those blades kill birds and bats.

Traditional spinning rotor windmills work. They're well understood. Big companies use them to produce utility-scale power, and sailboat owners use them to charge their batteries. But they're hardly the only players in the wind space.

(Images, top to bottom:

Cleanfield Energy Turbine;

Quiet Revolution eggbeater design;

A Windspire turbine;

Helix Wind's curved shape;

Windation's rooftop box;

Leviathan's Wind Lotus

In part because of the bird strike concerns, a great deal of research is going into alternative wind generators that don't have really high speed propellor tips.

A traditional windmill has what's called a horizontal axis—meaning the shaft that is spun by the props lies parallel to the ground. An alternative is a vertical axis unit, in which the spinning shaft sticks up in the air like a flagpole.

And there are absolutely dozens of these vertical axis designs: ones that

look like egg beaters, ones that look like a geneticist's double helix, ones that look like oil barrels with the sides ripped open.

The American Wind Energy Association ( says there are two basic kinds—lift-based and drag-based.

The little wind-speed devices with three spinning cups are drag-based. The cups never move faster than the wind speed, and generally move slower. The old Savonius Rotor system is another drag-based unit. These generally don't work real well to generate electricity.

There are lots of lift-based designs. They look, as mentioned above, like egg beaters. They can have vertical blades spinning around a vertical shaft. And there are those intriguing helix designs.

Many of them are unlikely to cause bird strikes, largely because they appear from a distance like a solid object.

The longer our energy crisis goes on, the more options present themselves.

If there are companies out there with different designs, send up an image and some background and we'll be pleased to post it. The email is

© Jan TenBruggencate 2009

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