| By :
Roger Brown
If you are checking into the possibility of a vertical helix wind turbine for your home, you need to be careful. All wind turbines are not created equal. Vertical helix windmills are becoming very popular because of their aesthetic elegance and small footprint. However, they are weak in several key design areas that you need to know about before you move forward to purchase. Here are the key factors I would like you to consider: 1. Power Output The design of the vertical helix wind turbine is very simple. Most units are of the "Savonius" type, which conceptually resemble a 55-gallon barrel cut in half. Before Sigurd Savonius claimed it and named it, the design actually goes back to 1745, in Furstenburg, Germany. They are drag-type devices though and do not generate aerodynamic lift, as do blades on horizontal wind turbines, or on other vertical windmills. The term we use to describe how well a mechanical system converts wind energy to electricity is "efficiency". With wind turbines the efficiency of the machine is influenced by a number of factors, but ultimately it just means the windmill's ability to generate the pushing force of the wind into kilowatt-hours. With the vertical helix wind turbine much of what is gained in design simplicity is lost in aerodynamic efficiency. The most compelling selling point of any vertical wind system is that they can be mounted low to the ground or on roofs. The upside of low mounting height is obviously access - it is much easier to work on such a system if a problem occurs and repairs are in order. The downside of low mounting height though is the wind down low is of much lower quality. It is very chaotic and not steady like the wind flow above the treeline. Savonius systems operate with efficiencies in the 5-10% range. In contrast, a Darrieus type vertical helix wind turbine's efficiency however is a higher - in the 30% range. Theoretically, a very efficient horizontal-axis wind turbine can operate in the 59% range, though. 2. Cost Ranging to over $17,000 for a 4.5 kW system, the vertical helix wind turbine can be very expensive for the amount of power it delivers. 3. Aesthetic Appeal Vertical helix windmills are compact, have a small footprint, and are pleasing to look at. Recent studies have shown that people just like looking at the vertical helix wind turbine. Because of "frequency effect", watching them can be very calming - like watching waves at the beach. In conclusion, sky-high fossil fuel prices - combined with current federal and state tax credits in the U.S. - have created a real worldwide appetite for most wind-related products now. If vertical helix wind turbines weren't so expensive we could live better with their inefficiency. As more units are sold, prices will come down. Until then, horizontals are a lot better for the money at turning the wind into electricity. The vertical helix wind turbine just isn't ready for the home market yet. There are just too many more efficient alternatives that produce more power and cost a lot less.
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