Renewable Energy AeroVironment and Swift small wind trubines

Published on September 12th, 2008 | by Philip Proefrock

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New Options for Home Wind Power

Swift and AeroVironment turbinesUtility-scale windpower is an important and growing part of the US energy portfolio. Farms ranging in size from dozens to hundreds of turbines can produce in excess of 60 megawatts of power. Plans for gigawatts of wind power are being proposed all over the globe, and new wind farms are regularly being proposed that outstrip one another to be the largest in their respective locations, or in the world. At the far end of the scale, the largest size wind turbines have a rotor diameter of 126 meters (413 feet), and are estimated to be capable of producing 20,000,000 kilowatt hours of electricity annually (enough to power as many as 5000 European homes). Since the power generated by a turbine increases exponentially as it gets larger, new turbines will continue to grow in size.

But small-scale turbines are perhaps a more exciting realm of development. The standard, propeller-style turbine is well established, and there are many suppliers for this kind of generator in a range of sizes. In 2007, Home Power Magazine had a roundup of more than a dozen small wind turbines ranging from 8 feet to 56 feet in diameter (the latter of which is far larger than even a large, inefficient household would need for their power requirements). Green Building Elements had a review of this article last year.

Besides the propeller turbine, there are a number of other options that are being developed and coming into availability that offer different features and performance that can make them appealing alternatives for some.

Vertical-Axis Wind Turbines

Helix Wind and Windspire vertical axis turbinesIn theory, vertical-axis wind turbines are thought to be better suited for urban locations, where winds are more swirling and less consistently directional. With a rotor that spins around an upright axis, wind coming from any direction can turn the blades and provide power. On the downside, the power produced by a VAWT is less efficient because, during part of its rotation, the rotor is moving against the wind.

Vertical-axis turbines are also generally quieter than horizontal, propeller style turbines. Their cylindrical form also lets them go into places with less space available, which also makes them well suited for urban uses. Another benefit of vertical turbines is that they generally appear more solid, which makes them less of a hazard to birds and bats.

The Windspire is one newer VAWT that is being aimed at the home-power market. It is a very narrow cylinder only 2 feet (61 cm) wide, but 30 feet (9.1 meters) tall. Another VAWT, the HelixWind presents an even more solid-looking presence, with scoop-like solid rotors in a helical configuration. The Windspire rotor is wider and shorter – 4 feet x 8.7 feet (1.2 x 2.7 meters) than the Windspire. Helix Wind also has a taller version with twice the rated capacity.

Loopwing and Energy Ball

Loopwing and Energy Ball turbinesMore than a year ago, we first learned about the Loopwing, an unusual turbine from Japan that offered extremely quiet operation and redundant safety systems to prevent overspeed in high winds. The noise reduction is due to the configuration of the blades, which return to the shaft, rather than having exposed tips. This eliminates the vortices that are produced by the tip of the blade moving through the air which is the source of much of the noise created by a turbine.

Another turbine has recently been introduced with some similar characteristics. The Energy Ball looks like a variant on the Loopwing concept, though with more blades. However, the Energy Ball is a small turbine only slightly more than one meter in diameter, with a rated power of only 100 watts (0.2 kW). Even in a very windy location, this small turbine is unlikely to do much on its own to reduce your energy bills because of its small level of output.

Other Small Turbines

Swift and AeroVironment turbinesSwift makes a turbine that is much like an ordinary horizontal-axis turbine, but unlike other propeller style turbines, though, its five blades are connected together with a ring. This makes it a hybrid between a propeller turbine, and a turbine like the Loopwing or the Energy Ball. The ring helps to cut down on noise, most of which comes from blade tips traveling through the air, not unlike the Loopwing or the Energy Ball.

AeroVironment has another turbine designed for direct mounting on a building parapet. The AVX1000 is designed for commercial use only. Aerovironment’s turbines can be installed with a decorative canopy that may also lessen the likelihood of bird impacts.

Both the Swift and the AeroVironment turbines are displayed in building parapet installations where they are only a short distance above a building roof. They may be taking some advantage of the increase in wind speed that occurs at a building roof. But when the wind is blowing parallel to the face of the building, these turbines are likely to be fairly ineffective.

Summary

  • AeroVironment AVX1000 – 5.5 ft (1.7 m) dia – rated power 1.0 kW (@ 13.4 m/s 30mph)
  • Energy Ball – 3.6 ft (1.1m) dia – rated power 0.1 kW (max 0.5 kW @17 m/s)
  • HelixWind S322 – 1.21m x 2.65m (4 ft x 8.66 ft) – rated power 1.88 kW
  • Loopwing – 9.4 ft (2.85 m) dia – rated power 2 kW (@12.8 m/s)
  • Swift – 7 ft (2.1 m) dia – rated power 1.5 kW (@ 14m/s 31mph)
  • Windspire – 0.6 x 6.1m (2 ft x 20 ft) – rated power 1.2 kW (@ 11.2 m/s 25mph)

Comparing Turbines

Evaluating and comparing wind turbines is still a difficult task. Different manufacturers list information about their turbines differently, so straightforward comparisons between units can be difficult. Some manufacturers list the output based on the maximum output, which is typically far in excess of the average wind speed a site is likely to experience.

Furthermore, how a turbine performs at different wind speeds also affects its output. Some manufacturers list an annual power output (in kilowatt hours, just like electric service is typically billed) but that is based on an estimated average annual wind speed, which may not be the same as the average wind speed a potential user’s site may experience.

Another factor is the “cut in speed” of a particular turbine, which is the wind speed at which the turbine starts turning. Some minimal amount of power may be produced at this low speed, but it is only a tiny fraction of the turbine’s rated speed. A turbine with an especially low cut in speed will start turning in a lighter breeze, but that doesn’t mean it is going to be producing much power at those wind speeds.

Wind power has not been quite as readily accepted for home power generation for several reasons. First of all, wind power has greater requirements for open space and access to wind for efficient operation. By comparison, solar is much easier to accommodate, especially on a small site. Solar is also far less obtrusive than wind power. Solar panels located on a low slope roof or in a back yard are often almost invisible to passers-by, while wind turbines need to stick up into the air where they are able to catch the wind. Some people find this objectionable, which can sometimes make it more difficult to obtain the necessary permits for the installation of a wind turbine. Any system with moving parts is more prone to breakdown and trouble than one that is solid state, which also contributes to wind power being less desirable for homeowners who do not also want to be turbine mechanics. Wind turbines also can produce noise and vibration. This, too can be objectionable to neighbors, as well as making it less desirable to mount the unit directly on a building. However, there are cities where zoning laws are being changed to allow for wind turbines to be installed with fewer regulatory hurdles.

Home wind power is still a small niche compared with solar. Far fewer homes are suitable for personal wind turbines than homes that can accommodate solar panels. But wind is part of the renewable energy mix, and there certainly are many homes where is is a viable option. For those, the range of options is growing.

This article was cross-posted at EcoGeek.org and GreenBuildingElements.com.




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About the Author

Philip Proefrock is an architect and photographer in southeast Michigan. He is also a LEED Acredited Professional. His professional involvement with green building includes working as project architect for the award-winning Malletts Creek Branch Library for the Ann Arbor District Library, which received the 2005 AIA Michigan Sustainable Design Award, and which was the first completed commercial vegetated roof (green roof) in the state of Michigan. He is an active member of Green Drinks Michigan/o2 Network. In addition to being lead writer for Green Building Elements, he is also a contributing writer for EcoGeek.org and for JetsonGreen.com. spurious nelogism (personal LiveJournal) Green Options articles StumbleUpon profile



22 Responses to New Options for Home Wind Power

  1. Uncle B says:

    Wind /battery power is great if your consumption level is realistic! We need ‘fridges that use super-insulation, and ground water , outdoor wind cooling of coils and solar pumps – a much more efficient fridge must be developed than is used now, and probably with a smaller interior space! A zero-running cost, zero upkeep home is possible with current technology, incongruent with current lifestyles and demanded by energy shortages! We are in a bind, aren’t we! If the depression deepens, and all indications, (Freddy Mac Fannie Mae Lieberman collapse etc) are in that direction, the better technology will be applied by necessity and we will all use less energy – a good thing for the economy and America! Back to Walden Pond folks, but this time with modern technology to the rescue and less consumption is better where energy is concerned!

  2. Uncle B says:

    Wind /battery power is great if your consumption level is realistic! We need ‘fridges that use super-insulation, and ground water , outdoor wind cooling of coils and solar pumps – a much more efficient fridge must be developed than is used now, and probably with a smaller interior space! A zero-running cost, zero upkeep home is possible with current technology, incongruent with current lifestyles and demanded by energy shortages! We are in a bind, aren’t we! If the depression deepens, and all indications, (Freddy Mac Fannie Mae Lieberman collapse etc) are in that direction, the better technology will be applied by necessity and we will all use less energy – a good thing for the economy and America! Back to Walden Pond folks, but this time with modern technology to the rescue and less consumption is better where energy is concerned!

  3. Anna says:

    With any of the above turbines, I would make sure there is third party verfication as to what will be produced. In addition, these systems are pretty small. What are we talking about in kilowatt generation and price?

  4. Anna says:

    With any of the above turbines, I would make sure there is third party verfication as to what will be produced. In addition, these systems are pretty small. What are we talking about in kilowatt generation and price?

  5. The rated output listed by the manufacturer is factual information based on the engineering of the turbine. But asking how much energy you will get from it is akin to asking how much gasoline you will use in a year – there are many other factors that will influence that answer.

    Price information for most of these is listed on the manufacturers’ sites (follow the links in the Summary to go directly to the company info). The rated power of each is listed in the Summary as well, ranging from 0.1 kW to 2 kW.

  6. The rated output listed by the manufacturer is factual information based on the engineering of the turbine. But asking how much energy you will get from it is akin to asking how much gasoline you will use in a year – there are many other factors that will influence that answer.

    Price information for most of these is listed on the manufacturers’ sites (follow the links in the Summary to go directly to the company info). The rated power of each is listed in the Summary as well, ranging from 0.1 kW to 2 kW.

  7. Ugly, noisy, unreliable, inconsistent… surely there must be a better solution than to live below a giant rotating turbine. Not too bad I guess if you can put the wind farms in places that nobody cares about or wants to see. Some day we will remember fondly the days of clear horizons and brown tinted skys…

  8. Ugly, noisy, unreliable, inconsistent… surely there must be a better solution than to live below a giant rotating turbine. Not too bad I guess if you can put the wind farms in places that nobody cares about or wants to see. Some day we will remember fondly the days of clear horizons and brown tinted skys…

  9. jerrod l henry says:

    Dont be kooks and whiners you should be encouraging development on all scales of new energy sources. I bet every one of you has an SUV uses AC and drinks cold milk from a fridge.

  10. jerrod l henry says:

    Dont be kooks and whiners you should be encouraging development on all scales of new energy sources. I bet every one of you has an SUV uses AC and drinks cold milk from a fridge.

  11. Take a look at http://www.allsmallwindturbines.com for an overview of all small wind turbines in the world.

  12. Take a look at http://www.allsmallwindturbines.com for an overview of all small wind turbines in the world.

  13. David Anderson says:

    Great post. Small wind just needs a few more years and some policy support.

  14. Jeff Bach says:

    Even in a liberal bastion of hippiness filled with alternative energy fruitcakes that is Madison, WI. I am dismayed at the lack of knowledge amongst officials, regulators, and policy makers. Clearly these people are not YET amongst the forward-leaning and forward-thinking crew that needs to be creating, setting, and implementing the social policies that small wind energy needs to become something viable. It certainly does look like small wind needs time to get into the marketplace and be discovered by the people who ultimately will legislate and regulate how it all fits together.

    Clearly stated – I have been discouraged by the lack of awareness, enthusiasm, and knowledge that everyone I have spoken to in city, county and state government has displayed here in Madison, Dane County, Wisconsin. They are all good people, it’s just that I get the impression small wind is not even on their radar yet.
    Its time is coming!
    Jeff Bach
    Quietwater Films
    Madison, WI.

  15. Jeff Bach says:

    Even in a liberal bastion of hippiness filled with alternative energy fruitcakes that is Madison, WI. I am dismayed at the lack of knowledge amongst officials, regulators, and policy makers. Clearly these people are not YET amongst the forward-leaning and forward-thinking crew that needs to be creating, setting, and implementing the social policies that small wind energy needs to become something viable. It certainly does look like small wind needs time to get into the marketplace and be discovered by the people who ultimately will legislate and regulate how it all fits together.

    Clearly stated – I have been discouraged by the lack of awareness, enthusiasm, and knowledge that everyone I have spoken to in city, county and state government has displayed here in Madison, Dane County, Wisconsin. They are all good people, it’s just that I get the impression small wind is not even on their radar yet.
    Its time is coming!
    Jeff Bach
    Quietwater Films
    Madison, WI.

  16. Pingback: Your Furniture » Blog Archive » New Options for Home Wind Power

  17. Pingback: Inventor Patents “Tree-Hugging” Hollow Wind Turbine For Urban Areas | Green

  18. Rif says:

    @AllSmallWindTurbines
    Great! Thanks for that overview.

  19. Rif says:

    @AllSmallWindTurbines
    Great! Thanks for that overview.

  20. firestar says:

    Before you try to build you own solar power, you need to have the right tools. You need to have the step-by-step process that I explain in this guide. I made it a personal mission to create the best solar panel guide available. I searched the internet for months looking for the best ideas and designs for building solar panels.Step-by-Step pictures, diagrams and schematics show you how everything is done. There is even a Video Library so you can see real solar panels being created. Learn how to take the power your solar panels create and run your household energy needs (controller, batteries, inverter, disconnects, etc). http://www.green-wind-solar.easy-go.biz/

  21. firestar says:

    Before you try to build you own solar power, you need to have the right tools. You need to have the step-by-step process that I explain in this guide. I made it a personal mission to create the best solar panel guide available. I searched the internet for months looking for the best ideas and designs for building solar panels.Step-by-Step pictures, diagrams and schematics show you how everything is done. There is even a Video Library so you can see real solar panels being created. Learn how to take the power your solar panels create and run your household energy needs (controller, batteries, inverter, disconnects, etc). http://www.green-wind-solar.easy-go.biz/

  22. interesting idea ..we need alternative energy

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