CleanTechnica

Walking the floor of WINDPOWER 2008, the annual conference and trade show for the wind energy industry, one couldn’t help but be transfixed by all of the different types of turbines - at least I couldn’t. The wind turbine has become the iconic symbol of clean, renewable energy. But the classic three-bladed horizontal axis wind turbine, with its gracefully swooping blades, has become the symbol of not only renewable energy, but also of environmental consciousness and ecological possibility.

Despite the ubiquity of the three-bladed turbine, the oft-overlooked vertical-axes turbines are making quite a splash in the world of wind energy, especially in small and micro-applications. So what’s all the fuss about? Vertical-axis turbines apparently do not suffer from some of the same problems that plague small wind applications in urban settings including, aesthetic concerns, space requirements and sound levels.

Other advantages of vertical-axis turbines:

• Can produce up to 50% more electricity per year than conventional turbines with the same swept area
• Generate electricity at much lower wind speeds, as low as 4 mph (1.5 m/s)
• Will continue to generate power in high wind speeds, up to 130 mph (60m/s) depending on the mode
• Direct-drive units have no gearbox. No gearbox means a more efficient transfer of energy and no leaking oil
• Will not harm wildlife, in terms of bird and bat strikes

Below, I’ll cover some more basic differences and show you a few photos and short videos of some of these turbines I saw down in Houston at WINDPOWER 2008.

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The designers from Taiwanese start-up A.N.I.T.A. Energy (pictured above) showed me why their models have a low start-up wind speed, and that is because of the light metal bands you can see surrounding the turbine itself. Apparently this design allows users with a less substantial wind resource (particularly those in urban applications), squeeze some electricity from the local winds. The larger model pictured above (and in the second video below) is scalable and can be stacked as many as three-high and integrated with the rooftops of large buildings.

Unlike three-bladed designs, vertical-axis turbines do not need to “right themselves” into the wind, they are always in a fixed position in terms of their orientation. A few of the models I saw, most notably the designs from the Korea-based KR Windpower, (video above) had a manifold-type device that would swing around and funnel more wind into the turbine from the direction the wind was strongest.

Another design I saw scattered throughout the show floor were those that integrated small solar and wind together on the same unit (top photo and photo below). The unit below integrates both solar and wind onto a single 400W streetlight platform.

The turbine itself is a “GUS” from a company called Tangarie which features a reflective coating that reduces glare and can even be slathered with an advertisement or a state flag of Texas, as is the one below. The complete solar/wind/streetlight/pole package (made by another company altogether) costs about $7,000, not including installation.

There will undoubtedly be substantial growth in the vertical-axis turbines, especially in urban settings. Personally, I think this technology could best be applied in poorer countries to help address the most basic of energy needs, like lighting and light-duty water pumping.

Other Posts on Small and Micro Wind Energy:

“Top Five Micro Wind Turbines”

“Liveblogging from WINDPOWER 2008: Photos of Small Wind Turbines”

“Small Wind Remains in Farm Bill”

All Photos © Timothy B. Hurst

*Thanks again to the American Wind Energy Association for providing travel and conference support to WINDPOWER 2008.

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