| By :
Roger Brown
Those who read this website are smarter than most folks and tend to know a lot already about wind turbines. They may already realize that the vertical wind turbines for the home is not ready yet.
What we will do here is go over the 4 main types and explain why they still are weak for home use. Let's step back for a moment and get clear first on the 2 main categories of wind turbines: 1. Vertical-axis wind turbine, or VAWT 2. Horizontal-axis wind turbine, or HAWT VAWTs are stronger in a few ways but fall short in a number of key areas, too: 1. Space they take up - Verticals do have a small footprint. Since they don't have large horizontally oriented blades to contend with, they can be mounted in just a few square feet. 2. Cost of the windmill itself - Horizontals are much cheaper than vertical turbines (vertical turbines can be up to 4 times more). 3. Aesthetics - Vertical turbines are more fun to look at doing their thing. Studies in Europe have shown that people like looking at their more rapid frequency almost as much as watching waves at the beach. 4. Efficiency - This is the killer for vertical turbines. Efficiencies can be 10 times less for them vs. a comparable horizontal. The reason is the amount of blade surface and the chaotic wind environments they tend to be placed in. 5. Upkeep costs - Maintenance costs on verticals is very high. The reason is they are exposed to much greater turbulence and the stresses brought on by that, damage key components. So, bottom line, since the purpose of the wind turbine is to most effectively convert wind into electricity, verticals are not the best choice of home turbine now. For the record though, here are the 4 main types of vertical wind turbines… 1. Savonius This is the oldest of the vertical designs. Savonius turbines are drag devices that resemble a cut in half 55-gallon barrel and have been around for hundreds of years in various work capacities - water wheel and wind. They are very inefficient - on the order of 5-10%. 2. Darrieus Darrieus wind turbines were patented back in the 1920's. These devices look like an eggbeater. In comparison to even an inefficient horizontal windmill, the Darrieus is still less efficient. The problem with them is they can't get started on their own. They need some type of power assist to get turning. That can be supplied by a small Savonius wind turbine or from a fossil fuel powered unit. 3. Giromill The Giromill is technically also a type of Darrieus wind turbine. It was actually included in the original patent by Darrieus. They look kind of like a cell tower, with 3-4 vertical blades extending off horizontal spokes. These units though have the advantage of being able to start on their own. 4. Rotational Sails This windmill looks just like it sounds like it would - harnessing wind just like a ship's sails do. The blades are made of fabric, so they're cheaper to make and cheaper to replace. The speed of the turbine is maintained by a magnetic control device that positions the sails to take maximum advantage of the prevailing wind. Summarizing, although the vertical wind turbine for the home is not ready to take over the market anytime soon, they do hold promise for the future. Until their prices come down a lot, issues with poor efficiency will haunt them. When prices do come down, consumers will be able to better live with the low efficiency numbers. Then, the smaller footprint and ability to locate vertical wind turbines in an urban on roofs and in smaller areas a horizontal just won't fit.
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