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Wind Power: Size Matters

There are a number of factors to consider when researching whether a wind turbine is the correct choice for your home’s off-grid power source. Issues such as your home’s overall power need, the location and topology of your property, and your budget will determine whether a wind turbine is appropriate for you.

Before reviewing your power requirements, first determine if your property has an appropriate space for a turbine. If your property does not receive a reasonably constant breeze, a turbine will not provide you with enough power. To determine whether your property meets this requirement, either hire an energy consulting service to test it or purchase/rent a recording anemometer—a device that measures wind speed. Measure wind speed at various locations on your property, in different seasons and in varying weather conditions for optimal results.

In order to produce usable energy, a turbine needs to receive a minimum wind speed of 7-10 mph. However, this “cut in” wind speed is not sufficient for most turbines to produce their optimal amount of power. Turbines have a rated speed, which is the wind speed required to produce maximum power. Rated speeds range from 25 to 35 mph, and turbines generally have a fail-safe that shuts them down if wind speeds exceed 45 mph.

The wind test will help determine if you have a clear area on your property that receives reasonably constant wind speeds of between 25-35 mph. If you do, your turbine will be able to provide you with the maximum power possible for that model. If you do not, you will have to estimate the amount of power the turbine can provide. Power graphs for various models are available online, and you can determine turbine wattage output based on average wind speed.

If you do not have an energy company available and cannot access a measurement device, wind maps are available online. These maps show general wind speed averages for different regions of the United States. Some locations have little to no information available on these maps, but they can provide estimates for a significant portion of the country.

If you have a suitable location for a turbine, the next step is to determine your household’s power requirements. Review your monthly electricity bill to determine your overall needs. Divide the monthly total by the number of days in the billing cycle to obtain a rough average of how much power your home needs every day. If you need to obtain a yearly total, add together 12 months worth of your bills or multiply the highest monthly total by 12 so as not to underestimate the amount.

Small Wind vs. Big Wind

Small wind is classified as any wind turbine that produces 300 kilowatts per hour or less. Different models in this category range between rooftop models that produce 200 watts of power to 75-meter towers that can produce over 250 kilowatts per hour. While small rooftop models may seem like a good deal—your turbine does not take up valuable land but still supplies free power—these smaller models are only good for supplying minimal power requirements such as irrigation systems, running one appliance or recharging batteries, or when supplementing another form of power such as the grid or solar panels. The maximum power output for rooftop models is less than one kilowatt per hour, and this is not sufficient to handle the full load for an average home.

Small towers are likewise constrained in application. As with rooftop models, the tower’s lesser height limits the possible turbine blade length. This restricts the amount of power that the model can provide, even if you have constant wind within the turbine’s rated speed range. If you choose to place a small turbine on a tall tower, it will also restrict the machine’s power capacity.

Big wind is considered as any turbine that produces over 300 kilowatts per hour, which includes turbines that can produce more than one megawatt of power. Towers that produce more than one megawatt per hour are generally used in wind farms to produce energy for the grid, and not for residential purposes. Towers that produce between 100 kilowatts to one megawatt per hour are good choices for a homeowner or business owner who wishes to get off the grid.

Carefully review your kilowatt requirements and compare them to available wind turbine models. To fully power an off the grid home or farm, you may require a tower that provides 300 megawatts of power. Consult with a wind power professional to ensure that your chosen model will adequately suit your needs. In addition, as wind speeds vary, you should consider purchasing batteries or a generator for backup power in case the wind is too weak or strong for your turbine to function and power your home, farm or business.

© 2008-2014 Off The Grid News

11 comments

  1. You need to review the wind turbine from Sauer Energy. Dieter Sauer’s company in northern CA is starting production on a vertical axis wind turbine that only requires a 6 MPH wind and is so compact that it requires only rooftop to place the unit. Check it out at: http://www.SauerEnergy.com

    • Folks, I think you need to rework your numbers. Your last paragraph says a home or farm might need 300 megawatts. Unless your home is the size of Al Gores ( and you have his finincial resources) you may have to settle for less.

  2. Palo Verde, the largest nuclear power plant in the US, just west of Phoenix generates 500 Megawatts..Yes I know Al Gores house doesn’y quite use that much.

    • Interested in what the nuclear power plant there cost to build and how much it costs per year to run. Divided out among the homes it powers, could it possibly be that we are being fed a bunch of bull? How much does it cost per kw? How does it compare with clean energy? My friends argue that nuclear is 24/7. Well so is tidal energy. And it’s green.

  3. Whoops, Palo verde generates 3.2 Gigawatts of electricity. My bad. Looking at my power bill I have used about 12-14 KILO watts a month. 300 kilowatts (not Megawatts) would power a very large house Even larger than Al Gores. Check your power bill.

    • again trying to help..again thnx 4 the prioevus nothing else but A.NO COMMENTS ON THE OTHER OPTIONS .except these there is another drawback .its when your brother breaks the solar panel after quarrel with you then no electricity will b produced .hope this funny answer u liked ..its just to make yahhooooooooooo answer FUNNNNN

  4. There is actually a newer style of wind turbine that cuts in at 2 mph wind speed, and doesn’t shut down until 42 mph. Produces up to 2500 Kilowatts/year, depending on your wind. Available, from of all places, Ace Hardware stores. Roof mounted, 6′ diameter, fairly quiet. Ask them about SKU 8233280. Made under the Honeywell name, around $6500, plus installation, plus etc.
    Worth looking into. Might make a nice addition to your cabin.
    Disclosure: I don’t work for an Ace store anymore, but I did… :-)

  5. Everyone keeps saying “bigger is better” and I just don’t get it. Granted, I don’t know much at all about this. I was wondering why a decorative windmill (like Tractor Supply carries) wouldn’t provide at least enough power to reduce your power bill. I was thinking if you combined one of these with a solar panel and charged batteries…? Being in an old mill community I just can’t see being able to put in one of these huge turbines, but a decorative windmill would be OK and no one would even know it was a working windmill.

    Please, some one who knows more tell me about this idea.
    Thanks

  6. A 7Kilowatt generator will run a battalion size camp. You wont be able to run everything you own, like hairdiers and video games all the time. But 7KW is a lot of power. Doubtfull that the decorative one could turn the electric motor portion that actully generates the elec charge.

  7. I got into wind power, solar, and hydropower back in 1978. Here’s what Iearned. Wind and solar do just fine, if they are cheap to make and to buy. Utilities want to increase the amount of money they make, so they build nuclear power for $ billions per reactor. You get to pay twice for nuclear power: Once for each Kw you buy; and A second time as a taxpayer to subsidize construction, to take on the burden of a serious accident, and to deal with spent fuel. If the nuclear subsidies had been directed instead into wind and solar, we would all be enjoying wind and solar power in our homes and businesses, backed up by natural gas fuel cell home generators by this time.

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