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3 Types Wind turbines

Wind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common.^[13]The three primary types:VAWT Savonius, HAWT towered; VAWT Darrieus as they appear in operation. Wind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common.^[13]

Horizontal axis

Components of a horizontal axis wind turbine (gearbox, rotor shaft and brake assembly) being lifted into position

Horizontal-axis wind turbines (HAWT) have the main rotor shaft and electrical generator at the top of a tower, and must be pointed into the wind. Small turbines are pointed by a simple wind vane, while large turbines generally use a wind sensor coupled with a servo motor. Most have a gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator.^[14]
Since a tower produces turbulence behind it, the turbine is usually positioned upwind of its supporting tower. Turbine blades are made stiff to prevent the blades from being pushed into the tower by high winds. Additionally, the blades are placed a considerable distance in front of the tower and are sometimes tilted forward into the wind a small amount.
Downwind machines have been built, despite the problem of turbulence (mast wake), because they don't need an additional mechanism for keeping them in line with the wind, and because in high winds the blades can be allowed to bend which reduces their swept area and thus their wind resistance. Since cyclical (that is repetitive) turbulence may lead to fatigue failures, most HAWTs are of upwind design.

11 x 7,5 MW E126 Estinnes Windfarm, Belgium, July 2010, one month before completion, with unique 2 part blades

Modern wind turbines

Turbine blade convoy passing through Edenfield in the UK

Turbines used in wind farms for commercial production of electric power are usually three-bladed and pointed into the wind by computer-controlled motors. These have high tip speeds of over 320 kilometres per hour (200 mph), high efficiency, and low torque ripple, which contribute to good reliability. The blades are usually colored light gray to blend in with the clouds and range in length from 20 to 40 metres (66 to 130 ft) or more. The tubular steel towers range from 60 to 90 metres (200 to 300 ft) tall. The blades rotate at 10-22 revolutions per minute. At 22 rotations per minute the tip speed exceeds 300 feet per second (91 m/s).^[15][16] A gear box is commonly used for stepping up the speed of the generator, although designs may also use direct drive of an annular generator. Some models operate at constant speed, but more energy can be collected by variable-speed turbines which use a solid-state power converter to interface to the transmission system. All turbines are equipped with protective features to avoid damage at high wind speeds, by feathering the blades into the wind which ceases their rotation, supplemented by brakes.

Turbine design and construction

Wind turbines are designed to exploit the wind energy that exists at a location. Aerodynamic modeling is used to determine the optimum tower height, control systems, number of blades and blade shape.
Wind turbines convert wind energy to electricity for distribution. Conventional horizontal axis turbines can be divided into three components.

• The rotor component, which is approximately 20% of the wind turbine cost, includes the blades for converting wind energy to low speed rotational energy.
• The generator component, which is approximately 34% of the wind turbine cost, includes the electrical generator, the control electronics, and most likely a gearbox (e.g. planetary gearbox,^[25] adjustable-speed drive ^[26] or continuously variable transmission^[27]) component for converting the low speed incoming rotation to high speed rotation suitable for generating electricity.
• The structural support component, which is approximately 15% of the wind turbine cost, includes the tower and rotor yaw mechanism.^[28]

A 1.5 MW wind turbine of a type frequently seen in the United States has a tower 80 meters high. The rotor assembly (blades and hub) weighs 48,000 pounds (22,000 kg). The nacelle, which contains the generator component, weighs 115,000 pounds (52,000 kg). The concrete base for the tower is constructed using 58,000 pounds (26,000 kg) of reinforcing steel and contains 250 cubic yards (190 cubic meters) of concrete. The base is 50 feet (15 m) in diameter and 8 feet (2.4 m) thick near the center.^[29]

Vertical-axis wind turbines Guide

Vertical-axis wind turbines

Vertical-axis wind turbines (or VAWTs) have the main rotor shaft arranged vertically. Key advantages of this arrangement are that the turbine does not need to be pointed into the wind to be effective. This is an advantage on sites where the wind direction is highly variable, for example when integrated into buildings. The key disadvantages include the low rotational speed with the consequential higher torque and hence higher cost of the drive train, the inherently lower power coefficient, the 360 degree rotation of the aerofoil within the wind flow during each cycle and hence the highly dynamic loading on the blade, the pulsating torque generated by some rotor designs on the drive train, and the difficulty of modelling the wind flow accurately and hence the challenges of analysing and designing the rotor prior to fabricating a prototype.^{[citation needed]}
With a vertical axis, the generator and gearbox can be placed near the ground, using a direct drive from the rotor assembly to the ground-based gearbox, hence improving accessibility for maintenance.
When a turbine is mounted on a rooftop, the building generally redirects wind over the roof and this can double the wind speed at the turbine. If the height of the rooftop mounted turbine tower is approximately 50% of the building height, this is near the optimum for maximum wind energy and minimum wind turbulence. It should be borne in mind that wind speeds within the built environment are generally much lower than at exposed rural sites.^{[citation needed]}

[edit] Subtypes

Darrieus wind turbine of 30 m in the Magdalen Islands

Darrieus wind turbine 

"Eggbeater" turbines, or Darrieus turbines, were named after the French inventor, Georges Darrieus.^[17] They have good efficiency, but produce large torque ripple and cyclical stress on the tower, which contributes to poor reliability. They also generally require some external power source, or an additional Savonius rotor to start turning, because the starting torque is very low. The torque ripple is reduced by using three or more blades which results in greater solidity of the rotor. Solidity is measured by blade area divided by the rotor area. Newer Darrieus type turbines are not held up by guy-wires but have an external superstructure connected to the top bearing.^{[citation needed]}

Giromill

A subtype of Darrieus turbine with straight, as opposed to curved, blades. The cycloturbine variety has variable pitch to reduce the torque pulsation and is self-starting.^[18] The advantages of variable pitch are: high starting torque; a wide, relatively flat torque curve; a lower blade speed ratio; a higher coefficient of performance; more efficient operation in turbulent winds; and a lower blade speed ratio which lowers blade bending stresses. Straight, V, or curved blades may be used.^{[citation needed]}

Twisted Savonius

Savonius wind turbine 

These are drag-type devices with two (or more) scoops that are used in anemometers, Flettner vents (commonly seen on bus and van roofs), and in some high-reliability low-efficiency power turbines. They are always self-starting if there are at least three scoops.

Twisted Savonius 

Twisted Savonius is a modified savonius, with long helical scoops to give a smooth torque, this is mostly used as roof windturbine or on some boats (like the Hornblower Hybrid).

vertical-axis wind turbines

Today I was asked what is a ‘vertical-axis wind turbines‘. Good question if you think about it because without a picture it is hard to explain. It is a wind mill that points up but captures wind from the side, right? (that made me grin) See the picture here… kinda like that, but what is a vertical-axis wind turbine? A vertical-axis wind turbine is a type of wind turbine where the main rotor shaft is set vertically. Among the advantages of this arrangement are that generators and gearboxes can be placed close to the ground, and that VAWTs do not need to be pointed into the wind. Thus they are omni-directional or do not have to be pointed when the wind changes directions. This is really great for areas where the wind shifts directions often or is generally erradic in nature. The vertical-axis wind turbine seems to thrive in this type of environment.
Want to know more about vertical-axis wind turbines and the green energy they produce?

Vertical axis wind turbine

The world's tallest vertical-axis wind turbine, in Cap-Chat, Quebec

Vertical-axis wind turbines (VAWTs) are a type of wind turbine where the main rotor shaft is set vertically and the main components are located at the base of the turbine. Among the advantages of this arrangement are that generators and gearboxes can be placed close to the ground, which makes these components easier to service and repair, and that VAWTs do not need to be pointed into the wind.^[1] Major drawbacks for the early designs (Savonius, Darrieus and giromill) included the pulsatory torque that can be produced during each revolution and the huge bending moments on the blades. Later designs solved the torque issue by using the helical twist of the blades almost similar to Gorlov's water turbines.

A VAWT tipped sideways, with the axis perpendicular to the wind streamlines, functions similarly. A more general term that includes this option is "transverse axis wind turbine". For example, the original Darrieus patent ^[2], includes both options.

Drag-type VAWTs, such as the Savonius rotor, typically operate at lower tipspeed ratios than lift-based VAWTs such as Darrieus rotors and cycloturbines.

[edit] General aerodynamics

The forces and the velocities acting in a Darrieus turbine are depicted in figure 1. The resultant velocity vector, , is the vectorial sum of the undisturbed upstream air velocity, , and the velocity vector of the advancing blade, .

Fig1: Forces and velocities acting in a Darrieus turbine for various azimuthal positions

Five-kilowatt vertical axis wind turbine

Thus, the oncoming fluid velocity varies, the maximum is found for and the minimum is found for , where θ is the azimuthal or orbital blade position. The angle of attack, α, is the angle between the oncoming air speed, W, and the blade's chord. The resultant airflow creates a varying, positive angle of attack to the blade in the upstream zone of the machine, switching sign in the downstream zone of the machine.

From geometrical considerations, the resultant airspeed flow and the angle of attack are calculated as follows:

^[3]

where is the tip speed ratio parameter.

The resultant aerodynamic force is decomposed either in lift (F_L) - drag (D) components or normal (N) - tangential (T) components. The forces are considered acting at 1/4 chord from the leading edge (by convention), the pitching moment is determined to resolve the aerodynamic forces. The aeronautical terms lift and drag are, strictly speaking, forces across and along the approaching net relative airflow respectively. The tangential force is acting along the blade's velocity and, thus, pulling the blade around, and the normal force is acting radially, and, thus, is acting against the bearings. The lift and the drag force are useful when dealing with the aerodynamic behaviour around each blade, i.e. dynamic stall, boundary layer, etc; while when dealing with global performance, fatigue loads, etc., it is more convenient to have a normal-tangential frame. The lift and the drag coefficients are usually normalised by the dynamic pressure of the relative airflow, while the normal and the tangential coefficients are usually normalised by the dynamic pressure of undisturbed upstream fluid velocity.

A = Surface Area

The amount of power, P, that can be absorbed by a wind turbine.

Where C_p is the power coefficient, ρ is the density of the air, A is the swept area of the turbine, and ν is the wind speed.^[4]

[edit] Advantages of vertical axis wind turbines

VAWTs offer a number of advantages over traditional horizontal-axis wind turbines (HAWTs). They can be packed closer together in wind farms, allowing more in a given space. This is not because they are smaller, but rather due to the slowing effect on the air that HAWTs have, forcing designers to separate them by ten times their width.^{[5] [6]}

VAWTs are rugged, quiet, omni-directional, and they do not create as much stress on the support structure. They do not require as much wind to generate power, thus allowing them to be closer to the ground. By being closer to the ground they are easily maintained and can be installed on chimneys and similar tall structures.^[7]

[edit] Disadvantages of vertical axis wind turbines

Some disadvantages that the VAWTs possess are that they have a tendency to stall under gusty winds. VAWTs have very low starting torque, as well as dynamic stability problems. The VAWTs are sensitive to off-design conditions and have a low installation height limiting to operation to lower wind speed environments.^[8]

The blades of a VAWT are prone to fatigue as the blade spins around the central axis. The vertically oriented blades used in early models twisted and bent as they rotated in the wind. This caused the blades to flex and crack. Over time the blades broke apart and sometimes leading to catastrophic failure. Because of these problem, Vertical axis wind turbines have proven less reliable than horizontal-axis wind turbines (HAWTs).^[9]

Research programmes (in 2011) have sought to overcome the inefficiencies associated with VAWTs by reconfiguration of turbine placement within wind farms. It is thought that, despite the lower wind-speed environment at low elevations, "the scaling of the physical forces involved predicts that [VAWT] wind farms can be built using less expensive materials, manufacturing processes, and maintenance than is possible with current wind turbines"

Small Wind Electric Systems

Small wind electric systems are one of the most cost-effective home-based renewable energy systems. These systems are also nonpolluting.

If a small wind electric system is right for you, it can do the following:

• Lower your electricity bills by 50%–90%
• Help you avoid the high costs of having utility power lines extended to a remote location
• Help uninterruptible power supplies ride through extended utility outages.

Small wind electric systems can also be used for a variety of other applications, including water pumping on farms and ranches.

Here you can find the following information:

• How a Small Wind Electric System Works

  Learn the basics of how a small wind system produces electricity.

• Evaluating a Potential Small Wind Turbine Site

  Start here to determine whether a small wind energy system would be feasible, practical, and economical for you.

• Small Wind Electric System Components

  Learn more about system components—turbines, towers, and balance-of-system parts.

• Installing and Maintaining a Small Electric Wind System

  Find out what you need to consider before you install a system, including basic maintenance tips.

Build a solar heater

Build a solar heater

By: Gary Reysa (www.builditsolar.com) © Gary Resa 2005
After walking into our new workshop one December morning and finding the inside temperature to be a bone-chilling 10°F (-12°C), I decided that it was time for a heating system! Given the rising costs of propane and our environmental concerns about using nonrenewable fossil fuels, a solar solution seemed fitting. I reviewed many solar collector concepts, and finally decided to install a thermosiphon air collector on the south wall of the building. The concept is elegant and simple. A thermosiphon design uses only the buoyancy of heated air to circulate air through the collector, eliminating the cost, maintenance, and energy consumption of fans, sensors, and controllers commonly used in other collector designs. On a sunny day, in a cold climate like ours here in Bozeman, Montana, this simple system can produce the heat equivalent of burning about 2 gallons (8 l) of propane. To minimize material use, I integrated the collector within the building’s structure. I also tried to make the collector easy to construct using readily available materials. In fact, making this collector should only take one trip to the hardware store and US$350. Set aside two or three days to complete the project.

Materials used to construct the thermosiphon collector can be found at most lumberyards and hardware stores.

How It Works

The thermosiphon collector consists of clear, corrugated poly carbonate panels fastened to vertical 2 by 6s. The clear panels, on the building’s south face, admit sunlight. An absorber—in this case, two layers of black metal window screen—suspended inside the collector captures the sun’s

heat energy. The air around the mesh expands and rises as it warms, creating a convection current. Vents located at the top and bottom of the collector allow air to circulate and become heated. Cool air enters the lower vent, is heated by the absorber, and rises through to the upper vents that exit into the building’s interior. This circulation of air continues as long as the sun shines on the collector. At night, as air in the collector cools to outside temperatures, airflow tries to reverse. Air in the collector sinks through the bottom vents and attempts to pull the warmed air from the building through the top vents. Use of flapper valves on the top vents helps prevent this reverse circulation and keeps the heat inside.

Nuts & Bolts

The collector is 20 feet wide by 8 feet high (6.1 x 2.4 m) for an overall area of 160 square feet (15 m2). The collector is 6 inches (15 cm) deep. In most cases, make the collector as large as your south wall allows (see sizing solar collector). The top vent and bottom vent areas should each be at least 50 percent of the collector’s horizontal cross-sectional area (again, more is better). The collector frame is constructed from wood, and consists of six vertical members, a bottom sill, and a top sill. The six vertical 2 by 6s divide the collector into five, 4-footwide (1.2 m) bays. A 2 by 6 is used for the bottom sill. A 2 by 8 is used for the top sill, which should be sloped at about 10 degrees to shed rain. The collector frame attaches to the building by lag bolts from the inside. The collector is glazed with clear Suntuf corrugated polycarbonate panels. These panels have an ultraviolet light-resistant coating on their sun-facing side to extend their life. Each panel is 26 inches (66 cm) wide by 96 inches (244 cm) high. There are ten panels. Pairs of 26-inch-wide panels are joined over a 1- by 1-inch (2.5 x 2.5 cm) vertical wood strip to make the 4-foot-wide panels for each bay. Two, 1- by 1-inch horizontal members provide additional support for the glazing. The absorber is installed on battens placed about halfway between the glazing and siding. After measuring the thermal performance with one, two, and three layers of window screening, I found that two layers work best.

Next

Disclaimer: Please use caution when working with tools such as saws, hammers, electric drills, etc.... Just because we feature these alternative energy how-to's does not directly imply that you will be able to do everything with any incident just by following the directions. Please make safety your number one concern! EnergyRefuge.com assumes no liabilities for accidents involving our instructions or those that are re-posted. Please use common sense and please consult a professional if needed.

Solar DIY/How-Tos

Everybody loves alternative energy how-to projects, so we are endeavoring to bring you the best alternative energy how-to's on the web. Check out our additions to the energy how-to section and leave some feedback for us in our forums. Our goal in providing this how-to section is to empower everyday individuals who seek to make change in their energy consumption and seek to move to alternative energy. We are here to share our experience in the alternative energy field, and hopefully it will inspire, encourage, and make a change in your energy use. Please contact us if you would like to submit a solar how-to or an alternative energy project.

Small Solar Electric Systems

Some of the alternatives for those looking to get cleaner electricity are small solar electric systems. Small photovoltaic (PV) systems can provide the ideal solution to locations where getting connected to the grid is impossible. They can be more efficient in sunny areas such as the American southwest, although they can work well in other types of climates, too.
PV small solar electric systems are designed to harness solar power as it hits the earth. These are crystalline silicon panels that capture sunlight and turn it into electricity, which is then stored in a battery bank. When battery charges drop below a certain level, the solar panels recharge the batteries. Photovoltaic panels can be mounted on a rooftop or a freestanding solar array rack.

Energy Savers recommends that before buying a small solar electric system the buyer should be sure that the site where it will be installed has enough solar energy to meet the electricity needs of the building, both efficiently and economically. The supplier can perform an analysis or give instructions on how to do that. It’s important to consider the geographic orientation and the tilt of the solar panels as these can affect performance. Still according to Energy Savers, it’s also important to accurately size the components of these small solar systems, especially when these are not connected to the grid (“stand alone”). The organization advises considering how much of the total electricity need the PV system would be expected to supply, which can be done by analyzing past electricity bills and consulting with a potential provider of small solar electric systems. Before installing small solar electrical systems, it is necessary to obtain permits from the city or county’s building department (a building or electrical permit, or both). The PV provider often looks after this for the client, but it’s important to make sure that permitting costs and responsibilities are addressed when negotiating an electricity system. Those who live in a homeowners association must also get approval from them, unless state laws say that citizens have the right to install a small solar system on the home. The fact is that the number of these types of systems is growing. Even a cold weather state like Minnesota has been registering record numbers of solar system installations (178 between January and November 2010), thanks to governmental incentives that have reduced costs per watt to $7.50.

Are You Ready to Build Your Own Wind Turbine?

Are You Ready to Build Your Own Wind Turbine?

Have you reached the point at which it would make sense to build your own wind turbine? If so, you’re definitely not alone!

We share a world in which the price of electricity is rising almost as quickly as the economic and job markets have crashed, leaving millions of homeowners desperate for ways to shave their monthly fuel bills. Switching to energy efficient appliances and light bulbs is a step in the right direction, but it’s only a baby step.

By deciding to build your own wind turbine, you’ll not only have a free and reliable energy source; you may even be able to sell the electricity you don’t use back to your electric company! You’ll also be protecting the environment and playing a small role in preventing climate change, because wind energy is clean energy. But what does it take to build your own wind turbine?

If the wind turbine you’re picturing stands a hundred feet tall with blades which would dwarf those on the propellers of the Titanic, relax. Not all home wind turbines are like the ones on utility company wind farms. They range in size from micro and pole-mounted models to those very tall stand-alone towers, and the sort of wind turbine you choose to build will depend largely on your location.

If your home is in an area surrounded by large buildings, the reality is that your local wind patterns probably won’t be regular enough for your wind turbine to generate more electricity than you’ll use in your own home. In that case, an inexpensive micro generator will be adequate. Using a micro wind turbine kit is the cheapest and easiest way to get the job done, but there are two caveats:

In an article, Discovery Channel News says that makers of some wind turbine kits might exaggerate the amount of electricity their products will produce in densely populated areas. Some of them, for instance, test their wind turbines on sea-level buildings in open areas when measuring the amount of watts of electricity they will produce at different wind speeds.

Some makers of wind turbine kits also claim their products will run silently and vibration-free. No wind turbine is either completely silent or completely still when the wind is blowing! So do your homework before choosing a micro wind turbine kit, and keep your expectations about the amounts of electricity you’ll be able to generate realistic.

But what if you have enough open land that deciding to build your own wind turbine on a tower? According to The Owner's Guide to Energy Independence Alternative Power Sources for the Average American, most homeowners who have installed residential wind turbines have placed their generators on towers at least in height. Principles of physics dictate that speed at which air moves decreases as it is closer to the ground, with the greatest increase in speed occurring between ground level and sixty feet.

The wind turbine you build will have three blades resembling airplane propellers, which are connected to a magnetic generator, which in turn creates electricity. As the wind speed increases, the rotors to which your three blades are attached will turn more quickly, and the higher they are from the ground, the stronger the wind turning them will be so the more electricity they will make.

You can also, if you decide to build your own wind turbine, increase the amount of electricity generates by increasing the size of its blades. The design of the wind turbine you build should ensure that will automatically turn sideways in extremely high winds. This will allow the plane of the blades, which is normally perpendicular to the access of the turbine, to change and reduce the amount of wind load it experiences.

If you live in an exceptionally windy area, your home wind turbine should either be attached to a collection of batteries, or to your local power grid. Batteries will enable you to store the excess power you generate for days when there is little wind. Being connected to the power gird means you can sell it to your electrical utility.

Finally, while installing a micro or rooftop wind turbine may be something you can handle either by yourself or with the help of a few friends, erecting a 60-foot (or higher) tower weighing several tons will require the help of professionals.

Also, the Homeowner's Guide to Energy Independence suggests that you set aside 1% of the total cost of installing your home wind turbine for yearly maintenance expenses. Maintenance should include an annual inspection by the people who installed your wind turbine system, who will go over it from the ground up looking for possible problems!

If you really want to build your own wind turbine, and understand what’s involved, the opportunities have never been better!

How to build your own wind turbine - Aeolos Wind Turbine LLC

How to build your own wind turbine - Aeolos Wind Turbine LLC

With the development of renewable energy, more and more people are interested in DIY wind turbine. How to build your own wind turbine for home?   There were some articles about how to build a DIY wind turbine however most of them are not easy to do or the DIY wind turbine is very simple.

Aeolos wind turbine tell you how to build your own excellent wind turbine.  Firstly, you should know how many parts are in a small wind turbine?

Blades:

You can buy from your local hardware shop or the blade manufacturers.  There are several materials of blades: Glass fiber, Aluminum alloy  or alloy steel.  At present, glass fiber blade is the most popular for small wind turbines.

Generator:

Generator is the heart of a wind turbine. An efficient and good quality generator is most important for a DIY wind turbine.  The following picture is the permanent magnetic generator of Aeolos wind turbine.

Turbine parts:

Other turbine parts included rotor, hub, bearing, gear, yaw and other parts. You can order these parts from the internet.

Control system:

The control system usually covered the control system and safety system.  An automatic brake system is necessary. It is better to set a mechanical hand brake.

Tower:

There are three types of wind turbine tower now (Guyed tower, Lattice tower, Monopole tower).  The height of tower and which type you should choose depended on you local site and  wind speed.

Some useful resources about how to build your own wind turbine.

How does my wind generator work?

How does my wind generator work?

Every wind generator, whether they produce enough energy to power a city or to power a small radio, works on these same basic principles...

1. The wind blows

2. The generator's vane (tail) causes it to turn into the wind

3. Blades attached to an alternator/generator experience the force of lift and begin to spin

4. The spinning creates electricity for us to use directly or to charge batteries

Sounds pretty simple eh? Well, then how the heck do I build one? Read on...

Tools Required

Surprisingly, building a simple wind generator only requires very basic hand tools, and if you are desperate you won't necessarily need all of them. I used...

• Jigsaw (or a hacksaw and a lot of determination)

• Drill

• (2) Drill Bits (1/2", 7/32")

• Tape Measure

• Crescent Wrench

• Pipe Wrench

• Protractor (to measure angles for the hub)

• Sandpaper (various grits)

Parts Required

I wanted to be as minimal as possible with my design (I'm poor), so I took the already simple designs from around the web and made them even simpler. All of the parts are available at any local home improvement or hardware store, and the entire setup can be constructed in as little as a weekend. Many of the parts you may already have lying around, and lots of substitutions can be made (instead of 1" steel pipe for the tower, you could use an antenna pole for instance). Here are the parts I used to build my generator...

• 10" x 14" Steel Sheet

• 10" x 1/4" Steel Nipple

• 1-1/4" Floor Flange

• 36" x 1" Square Tubing

• 1/2" Bore Circular Sawblade (for hub)

• 5/8" x 1/2" Arbor (to attach sawblade to motor shaft)

• (2) Metal Straps

• 8" x 4" PVC Pipe

• 30" x 8" PVC Pipe (6" pipe works well too)

• A DC Permanent Magnet Motor (preferably Ametek 30V or 260V 5A treadmill motor)

• (8) 1/4" Bolts (with washers and nuts)

• (2) 1/4" Sheet Metal Screws

• 10-40 Amp Diode (the bigger the better)

All of the above parts (with the exception of the motor), can be picked up in a single stop to any large hardware or home improvement store. For the motor, the most popular types are old tape drive motors manufactured by a company called Ametek. The key is to finding a motor that puts out the highest voltage per RPM. For instance, the Ametek I'm using is rated for 30V at 325 RPM, making it excellent as an electricity generator (for a nice output comparison of the Ametek motors commonly found on eBay and other sites see TLG Windpower). However, pretty much any permanent magnet motor with a good volt/RPM ratio will do. Keep in mind that if you want to generate useful electricity, you will need to produce at least 12V to charge deep cycle batteries or run an inverter. My setup can easily achieve 300-400 RPM in a pretty average wind (for Oklahoma). These instructions assume an Ametek motor with a 5/8" shaft, but can easily be adapted to other motors (search ebay for "wind generator" and you will get a listing of lots of good motors).

Blade Construction

Arguably, the most important part of a wind generator are its blades. A lot of people like to carve their own blades out of wood or composite materials. However, for the rest of us, it's quite easy to make a good set of generator blades from common PVC pipe (and the efficiency isn't too bad either). A 2-3 foot section of either 6" or 8" PVC pipe will do the trick. Before we go any further, here are a few blade theory quickies...

• The longer your blades are the more "swept area" you have to gather energy from and easier your blades will spin in low winds, but the slower your rotation speed will be

• The tips of the blades always spin faster than the base, therefore one needs to take into account the "tip speed ratio" (TSR) when designing blades (there is a reason why old farm windmills will spin all year long at 40RPM)

• The power that can be extracted from the wind increases by the cube of wind speed (something like P=k*v^3 k=constant of wind generator, v=wind velocity)

• According to the Betz Limit, only about 59.3% of power can be extracted from the wind (so in reality P=.593*k*v^3, assuming k accounts for mechanical inefficiencies in the generator motor)

• The higher you get the generator off of the ground, the more wind it will be exposed to (the general recommendation seems to be 25-50ft., but I've had decent results at just 12ft.)

Cutting the blades for this machine is very simple. You will need to cut your PVC pipe into 3 sections, two 150 degree sections and one 60 degree section (I've attempted to illustrate this VERY APPROXIMATELY in my favorite CAD program--and by CAD program I really mean MS Paint). The red lines are cut marks. You will want to use a good tape measure and possibly some construction paper or newspaper to mark everything before you cut. The 150 degree angles will result in wide blades that start up in lower wind speeds, however this will lower the shaft turning speeds. In practice, you will find that the optimum angle could be anywhere from 75-150 degrees. The best idea is start out with a wide set of blades that you can always thin out later if you need to. Remember, measure twice and cut once!

After the blades are cut, I like to go ahead and smooth out all of the edges. If you want to follow aerodynamic theory, you can round the angled (leading) edge and flatten the straight (trailing) edge, but in practice I haven't seen this make much difference with PVC blades. So, you should end up with something roughly like these...

Hub & Blade Assembly

The next obstacle is building a hub to attach the blades to. There are many types of ways that this can be done. I have used circular sawblades and scrap steel disks. I recommend the sawblade approach, as they are readily available and easy to drill through. You can pick up an arbor with a 5/8" or 1/2" shaft at any homestore that will attach directly to the sawblade. Using the 1/4" drill bit, you will want to drill 3 sets of 2 holes 1" apart which each set 120 degrees from the next (this is where the protractor comes in handy, unless of course you are a Euclidean purist in which case you probably don't need a protractor). Here is a picture to make it more clear...

It's a pretty simple idea, but circular sawblades have worked out very well for me as hubs. Be sure and get some sort of rubber covering for the tooth edges and/or file down the edges as best you can, because the last thing you want is a hub of death flying at you if your generator decides to rip apart!

After our holes are cut out and we are confident of our safety procedures, we attach the blades to the hub (note that the hub pictured was cut from scrap steel, more pictures to come later)...

Tail & Pivot Assembly

Now we need to build a spinning platform for our generator motor to rest on. To achieve this, we will use some square tubing, a pipe nipple, flange, and small sheet of steel. Here is my "CAD" draft of what I wanted my tail & pivot assembly to look like, and a real picture of some of the parts I used...


First, I recommend cutting the sheet steel with a jigsaw into a nice design for the the tail (Note: this step is quite unneccessary and ONLY for aesthethic reasons).



We then want to make a cut down the center of the square tubing. The length of the cut isn't that important, but I recommend about a 9" cut (this will help make balancing easier later on). We may then slide the tail metal into the hole and use the 1/4" drill bit to drill and attach the tail to the square tubing.




We will then want to cut out a weather covering for our motor. A piece of 4" PVC slips perfectly over the Ametek 30V motor that I use. I cut it out like so (note the side hole for the motor wires).



Then we go ahead and paint it all up to seal everything from the elements. I wouldn't recommend painting on your front porch like I did though...



After everything is painted, we can now put it all together. Take the floor flange and put it under the square tubing about 6"-7" from the head. Mark the holes and drill them out with the 7/32" drill bit (or any bit close to but smaller than 1/4"). Attach with the 1/4" sheet metal screws. Use the metal straps to secure the motor and cover assembly, screw on the pipe nipple and you should have something like this...

Tower Assembly

Every wind generator needs a tower. I built mine from some pipe fittings from my local hardware store. If you already have an antenna pole or electrical conduit lying around, then you can skip this section. Here is my recommended parts list for a small extensible tower...

• (2) 5' Sections 1" Pipe

• (1) 1" Pipe Coupling

• (3) 1" Pipe Elbows

• (4) 18" Pipe Sections

• (2) 12" Pipe Sections

The tower base is pretty self-explanatory. Just hook up the elbows and pipe sections to create a base similar to this...



From there we can attach the 2 5' sections of pipe together to form a nice strong mini-tower for our generator to sit atop...

Finished Product

Now we are ready to attach the blades to the motor shaft with the arbor. You will also want to go ahead and attach some wire to the motor and run it to a device to power or a bank of batteries etc...



Here is a picture of the experimental design using six blades. It would spin in practically no wind, but would never get past 100RPM. At least it looked interesting!


Here is the battery bank I'm feeding into in parallel with solar panels. I am just using two 12V marine deep cycle batteries that can be found at any place that sells car batteries. I keep them in a standard plastic tub with a hole cut in the sides for 12V fans I cannibalized from a couple of old Mac G4s (not pictured). Be sure and put a diode between the battery and the generator so that current doesn't flow from the battery to the motor.



It turns out, cutting the blades a little thinner works better for my area. So I used the large white blades from the previous picture and thinned them out a bit. This resulted in the fastest shaft speeds as seen in first video at the top of this page.


Thank You

Wind Turbine Tower Trends

by Paul Gipe
An edited version of this article appeared in WindStats Vol 8 No 1, (1st Quarter 1995) Portions of this article were adapted from Wind Energy Comes of Age Copyright 1995 by John Wiley & Sons. All rights reserved. "Jay Carter was right. There's wind up there," said one wag about the industry-wide trend toward tall towers. Jay Carter Jr. was the first to install medium sized wind turbines on towers taller than 30 meters. His 160-foot (49-meter) towers are a prominent, if jarring, feature of the landscape in California's San Gorgonio Pass where they look down upon a seething mass of 1000 turbines atop once commonplace 24 meter towers. But the shift is most apparent in Denmark (see accompanying table) and in Germany.
Winkra's revealing market survey shows all major European manufacturers offer 40 meter towers at a minimum. The German wind company's annual price list of products on the German market now shows that Bonus, Carter, Nordex, Nordtank, Nedwind, Tacke, Vestas, WindWorld, and WindMaster offer towers up to 50 meters in height. The fierce competition in the German market has led some manufacturers to stretch their tower designs slightly to gain an edge. Vestas offers a 53 meter tower, for example, while Enercon, long the height leader, advertises the availability of a 65 meter tower.
 Tower Height
 Zond's Finn Hansen says 60 meter towers may make sense in the interior of Germany or in forested belts of Northern Europe but he hasn't seen a need for them in North America yet. Still, much of the sales sizzle in the National Renewable Energy Laboratory's advanced wind turbine program is based on the promise tall towers offer. NREL, a U.S. government laboratory, attributes nearly half of the expected 50% improvement in wind turbine production from their research program to towers twice the height of those common in the late 1980s.
 NREL's advanced wind turbine program assumes that hub heights increase from 90 feet (27 meters), considered the base case, to 180 feet (55 meters) with only a 10% cost penalty. The tall tower is justified if there's a high wind shear, such as NREL believes exists on the American Great Plains. With wind shear approximating the 1/7 power law, doubling tower height will increase the power available in the wind 45%. NREL's research, says Sue Hock, has found wind shear greater than the 1/7 power law.
 Minnesota, currently a hotbed of wind activity, will be the first region on the Great Plains to test the merits of tall towers in North America. Minnesota's Department of Public Service is seeking funding for a series of tall anemometry towers to measure the wind shear up to 60 meters above ground level at several sites in the state specifically to evaluate the production benefits of taller towers.
There are less benefits from tall towers in Britain, suggests Andrew Garrad, where there's stronger winds at 40 meters than on the American Great Plains. In some cases, such as National Windpower's Bryn Titli site in Wales, there's planning pressure for shorter towers to reduce the obtrusiveness of the turbines. The Bonus 500 kW turbines at Bryn Titli were installed on 35 meter towers rather than the 40 meter towers that have become the norm.
 NREL's Hock says that turbines and towers need to be tailored to individual sites, and tower height is part of the equation in North America as well. Bob Lynette agrees. The choice of towers, he says, is site dependent. Lynette is testing a prototype of his Advanced Wind Turbine on a 140-foot (43-meter) guyed tubular tower on Tehachapi's Cameron Ridge. Lynette's AWT-26, a redesign of the ESI-80 undertaken as part of NREL's advanced wind turbine program (from which its name was derived), lends itself to tall towers, says Lynette. Guyed pole towers are an economical means for reaching the heights NREL envisions.
 Zond offers a 40 meter tower as standard with its new Z-40 turbine and provides a 50 meter tower as an option. Hansen notes that towers of other heights could be used in response to specific site conditions. Trees or other obstructions and terrain could dictate taller towers. The choice, Hansen says, rests with the customer.
 Tower height is not simply a question of better performance, says the Oregon Department of Energy's Don Bain. No question that "tall towers can make or break some installations," he says. But Bain wants to know how tall towers effect the cost of energy. He argues that "least cost optimization" could favor tall towers in low wind areas and shorter towers in high wind areas as suggested by Andrew Garrad in Britain. The optimum depends on tower configuration and its cost. Bain also notes that aesthetics will be an issue in some places. Tall towers are more visible than short towers. And though tubular towers are visible for great distances on the North American plains, Minnesotans prefer tubular towers for aesthetic reasons.
 Aerodynamicist Woody Stoddard, also observes that tall towers are "a damn good idea--if you have an elevator." Lifts would make it easier for able-bodied technicians to quickly service the nacelle. Lifts would also enable the handicapped to service the machines says Stoddard. Zond's Hansen doubts today's turbines can economically justify elevators, especially in California where Hansen finds Cal-OSHA's safety regulations too costly. But the question could be re-examined, he says, as turbines grow to nearly one megawatt in size.
Another limitation to tower height is regulations requiring distinctive marking of structures considered navigational hazards for aircraft. Marking has no effect on performance but does magnify the intrusiveness of wind turbines on the landscape.
 Obstruction Marking
 The intent of obstruction marking is to make structures such as wind turbines more visible to aircraft. The flashing lights and red and white bands commonly seen on radio masts increase the contrast between the mast and its surroundings. Unfortunately this would also heighten the contrast between wind turbines and the sky, making them more visible not only to aircraft but to the public as well. Imagine the outcry from the Country Guardians if every wind turbine in Britain sported a flashing strobe light or from a Dutch landscape protection society if every wind turbine in the Netherlands were painted in such garish colors as the NedWinds off Medemblik.
Every country has such a requirement, though the actual limit varies. In the United States the Federal Aviation Administration regulations state that any objects exceeding an overall height of 200 feet (61 meters) above ground level "should normally be marked and/or lighted." In Germany the "Luftverkehrsgesetz" requires obstruction marking of structures more than 100 meters (328 feet) above ground level.
German manufacturer Enercon offers 40, 50, and 65 meter towers for their E-40 model. The maximum height of the E-40 on a 65 meter tower is 85 meters (tower height plus rotor radius), well below the German obstruction limit. Local authorities could still require navigation lights if the turbine was installed near an airport or a prominent flight path. The same limitation applies in the United States for towers below 200 feet. If the turbine and tower are deemed a navigational hazard, marking is required.
 Enercon is moving toward a standard 50 meter tower height for the North American market. The resulting 70-meter height to the tip of the blade on their E-40 will put them well above the 200-foot limit in the United States. Like others who've examined the issue, Enercon's Mark Haller expects that it will be sufficient to light perimeters turbines of a multi-turbine array in the United States, or it may be adequate to only mark corner turbines. Though neither approach has been tested.
 According to Subpart 20 of the FAA regulations "an FAA aeronautical study may reveal that the absence of marking and/or lighting will not impair aviation safety." On paper at least towers can exceed 200 feet in the United States without the need for lighting or painting if they pose no hazard to aircraft. If WindStat's call to the FAA western regional office in Los Angeles was any indication of what it will be like dealing with the federal bureaucracy in the United States, wind companies are in for tough sailing. "I just don't have time to discuss it," said the FAA's Bud Whitfield.
 The only documented test of the FAA's response since Boeing's MOD-2 fiasco near Goldendale, Washington, which did require lights and painting, has been in New York state. There AWS Scientific filed notices with the FAA for Kenetech's demonstration project with Niagara Mohawk Power Co. in Denmark township. A turbine with a 130-foot tower was accepted, but lights were required on a hypothetical 33-meter turbine and 160-foot tower reaching a total height of 213 feet. Partly as result of that experience AWS's Bruce Bailey recommends towers at least 120-foot tall in New York state and believes towers up to 140 feet tall will be acceptable. But he suggests shying away from overall heights exceeding 200 feet because of FAA lighting requirements. Bailey also notes that exemptions are possible, but warns that exemptions may be difficult to obtain from an obstinate bureaucracy.
 It was the FAA's 200-foot limit that dictated the height of Carter's original tall tower says NREL's Paul Migliore. Though he wanted to go even higher, Carter specifically chose the 160-foot tower height to avoid dealing with the FAA. Carter's 160-foot tower and his 23-meter turbine put him at just below the limit at 198 feet.
Migliore notes that the issue of navigational lighting has been avoided until now because no one wants to spend the time fighting the FAA unless they need a permit for a specific project. "It's just a matter of time," says Earl Davis of the Electric Power Research Institute, before this issue is raised. Like Carter earlier, the tower height of EPRI's 6 MW demonstration of Zond's new Z40 turbine in Texas was limited to 40 meters (130 feet) even though Zond has long experience using 140-foot towers. Zond's Hansen notes that he has installed lights on turbines in Sweden and Germany. But both sites were near airports where the precaution was warranted.
 "The jury's still out," says Dan Juhl on the requirement for lights in the United States. "It depends on where you are." Juhl feels regulators in Midwestern states will be more accommodating than those in more densely populated regions of the country such as New York and California. After all wind turbines pose far less of a navigational hazard atop Minnesota's isolated Buffalo Ridge than they do in Israel's Golan Heights where ground-hugging flights by Israeli fighter bombers required Britain's Markham to candy-stripe their turbines. Nevertheless, Juhl says he doesn't believe there will be significant advantages from towers over 50 meters tall in the Midwest. The biggest limitation, he says, will be the large cranes necessary to install tall towers.
 Lattice versus Tubular
 In another contrast with the United States, Europeans have almost universally embraced tubular towers. While the trend toward taller towers in Britain is mixed, it has become clear that there's a planning presumption against lattice towers, because of their appearance says Andrew Garrad of Garrad Hassan partners.
There's also a clear preference for tubular towers among landowners in Minnesota, says John Dunlop, the American Wind Energy Association's Great Plain representative. Technicians familiar with the upper Midwest's frigid winters also favor tubular towers for the protection the towers provide from the wind.
 Skip DeLong of Southwestern Technical College in Jackson, Minnesota, says he "definitely prefers tubular towers" for maintenance in cold climates such as that of the upper Midwest. Like Stoddard, DeLong argues that wind turbines need to be "maintenance friendly and the tower is certainly a part of that" equation. DeLong worries that it may be difficult to do any service work on lattice towers in sub-zero (Fahrenheit) weather.
 "We always recommend tubular towers" even in the United States, says Vestas American's Oscar Holst Jensen. They do, says Jensen, for safety in cold climates, for better security (tubular towers have a lockable door), and for aesthetics. "They (the turbines) look much better on tubular towers," says Jensen. "But," he adds, "we give the customer the choice." Mirroring Southwestern Technical College's DeLong, Jensen argues that turbines on lattice towers will have lower availability in the Midwest than those on tubular towers. "It's a tricky business to climb a lattice tower in the winter in Minnesota."
 But the profit margins are so small in the North American market, says Jensen, that there's a lot of pressure to use lattice towers. For example, nearly all of Zond and Kenetech's turbines in California use lattice towers. Between them they produce a third of California's total wind generation. In Europe the planning pressure for tubular towers is so great that it's nearly impossible to use lattice towers except in Spain, and even there the trend is toward tubular towers.
 According to Vestas' Jensen, a tubular tower for a 500 kW V39 costs about $25,000 more than that for a lattice tower in the United States. The difference is only 4-5% of installed equipment costs. This compares well with the experience of Zond's Hansen. The truss tower and its foundation for Zond's first prototype of its Z-40 accounts for 15% of installed costs. The tubular tower and foundation for Zond's second prototype, says Zond's Hansen, accounts for 20-25% of installed cost.
 But lattice towers are more costly and difficult to assemble than tubular towers Jensen continues. Lattice towers require torquing 400-500 bolts, a small crane, and a lay-down yard or staging area for assembly. Complex terrain can complicate if not thwart use of lattice towers because of the need to transport lattice tower sections from the assembly yard to the final site. The transport of huge assembled lattice tower sections is a hair-raising experience and risky task.
 Kenetech, the sole U.S. turbine manufacturer with machines in the field, offers towers in two heights: 80 (25 meters) and 120 feet (37 meters). Like Zond Systems, Kenetech clearly prefers lattice towers because they are initially cheaper. But they will bow to local preferences and use tubular towers for their projects in Britain and the Netherlands as they did for Northern States Power in Minnesota. Kenetech is widely credited with successfully developing an aesthetically pleasing tubular tower for NSP's 25 MW project on Buffalo Ridge.
Kenetech will also use tubular towers to meet demands from wildlife agencies some of whom believe that lattice towers contribute to killing birds in the Altamont Pass. Kenetech's tubular towers were hardly in the ground in Minnesota when Kenetech announced that they planned to replace their lattice towers with their ungainly "Kenetower." The only advantage the Kenetower offers to traditional tubular towers, such as that used on the NSP project, is less costly foundations. By spreading the tower's legs over a wider footprint than that of a conventional tubular tower, the Kenetower requires less excavation and less concrete for its footings. But the resulting appearance of the tower may be too high a price to pay for lower-cost footings. Referring to the Kenetower's rocket-like shape, one wind pioneer caustically says it "would probably make it to the moon." He also notes that the open base of the tower provides only limited shelter to windsmiths during the winter.
 Crane Size
 "There are logistics problems" with bigger machines says Bob Lynette. The bigger turbines, those in the 400-600 kW range, are more difficult to transport and install, he says. Turbines have become so big that installation on 40 meter towers in California requires 160-ton, rigid-boom cranes. These cranes are costly and difficult to maneuver in rough terrain. A crane operator was electrocuted in the Tehachapi Pass when the boom on his crane inadvertently swung into power lines while he was driving on a winding wind farm road. These large cranes could become a limiting factor on turbine size and tower height.
The lightweight nacelle of AWT-26 lends itself to tall towers, says Advanced Wind Turbine's Bob Lynette. The AWT-26 only needs a 100-ton crane. "There's a place for smaller machines," says Lynette in reference to the AWT's 26 meter rotor, especially in Third World countries without large cranes.
Lynette offers towers up to 140 feet and a choice between a conventional lattice tower and a guyed tubular tower. There's a negligible difference in cost between the two tower types, says Lynette. But the tower alone of a "walk up" tubular tower like those used by other manufacturers, costs twice as much as AWT's guyed tower with its external ladder.
 The greater footprint of guyed tubular towers relative to conventional tubular and lattice towers may make them less desirable to farmers and ranchers who will have to dodge them with their tractors. The problem is not unlike that faced a decade ago by Carter with his slender guyed tower. Landowners may demand higher royalties to compensate for their trouble. It's conceivable that higher land leases for guyed tubular towers could offset their lower initial costs, boosting long-term operating costs.
This and other questions about optimum tower design and height await conclusive answers. In the meantime everyone agrees that Jay Carter Jr. was right, but how right remains to be seen.

How I Built a Wind Generator

How I Built a Wind Generator in My Backyard for $150

Lately I've been spending a great deal of time working on ways to generate my own electricity. It isn't a necessity for me yet, but someday being electrically self-sufficient could really come in handy. My interest started a while back when I stumbled upon a how-to article on building wind generators from treadmill motors and PVC pipe. It sounded easy enough, so I decided to try and design my own. This particular design can be built for $100-$150 if you are thrifty and can regularly generate 50-250 watts (considerably cheaper than a solar panel of similar power output). Here's how I built it for those of you who are interested. Additionally, please check out my new frequently asked questions page for more information not discussed in detail here.


Videos

Wind Turbines Vs. Solar Panels

Wind Turbines Vs. Solar Panels

June 28th, 2010 — 11:21am

What will work better: residential solar panels or wind turbines for the residence? A great deal will be based upon the region where you live as well as the weather conditions

there. Here we will check out the pros and cons of both starting off with the benefits of solar panels.
Solar panel pros:
1) Although commercial solar electricity systems are even now relatively expensive, the expenses are coming down. Best of all, your can assemble photo voltaic panels pretty easily and for roughly around $100 each. The actual construction of a photo voltaic panel is really really simple. You possibly have all or most of the tools you’ll have to have in your garage.
2) Solar panels are very easily added as time goes by. If you start with a smaller array, even one or two panels, you’ll be able to add to it as your time and money permit. Do not think as though you need to install an entire solar system to your property all at once. Get started now and at some point you’ll have a solar powered house. With every single panel you put up, you’ll have to buy less electricity from the utility company.
Solar panel cons:
1) Photo voltaic panels do not function at night. This isn’t a real disadvantage if you are still connected to the electrical grid. You’ll be able to buy electrical power at night and sell electricity you produce back to the power company in the day time. This ebb and flow of electrical power translates into no electric bill to pay each month.
2) Climate can be a limiting factor. Residential solar energy will work far better in Phoenix than it will in Seattle, but the fact is there’s adequate sunshine in almost every city and state inside the United States to make your own solar energy feasible.
Wind turbine pros:
1) Like solar, after your wind turbine for your residence is installed and operating, the maintenance is minimal. You can even construct your own wind turbine for under $150. Commercial wind turbines would cost a lot more, but if you know how simple they are to assemble there’s no reason to buy commercially.
2) Wind turbines for homes generate power day and night, whenever the wind is blowing. Like solar, some locations are going to be much better than others but wind power generators are absolutely realistic in most areas of the country.
Wind turbine cons:

1) A rooftop wind turbine could be a bird hazard. On occasion birds fly into the blades of rooftop wind turbines and are injured or killed. The hazard is really no more than the smaller windmills you see for irrigation on farms. The bird hazard is actually significantly more a concern with large wind farms situated in major bird migration routes like the ones in Southern California.
2) Wind turbine generators make noise. Unlike a residential solar panel which is 100 % silent, a residential wind generator will make a whoosh whoosh sound as it spins.
Whichever you decide on, photo voltaic or wind power, you’ll be a winner and so will the environment. You will have lower or no electric bills and there will be less carbon dioxide spewed into the atmosphere. And here’s a thought for your future: Nissan now sells an all electric vehicle, the Leaf, and many more car manufacturers will have them in the foreseeable future. Imagine never having to pay for gasoline once you generate your own power at home.

Comment » | wind turbines

What to Know in Residential Wind Turbines

June 28th, 2010 — 11:19am

When you think about wind turbines, the tower with four blades reminiscent of Holland country landscape with the tulips and the Dutch gal is the first image that may come to mind. That image of a windmill seems a prototype of the mechanical wind turbine, also called aerogenerator that uses the wind energy to turn kinetic energy to electricity. It is also one of the mechanical inventions requiring great respect for it helps in alleviating the over-dependence of fossil fuels in generating electricity to power homes.
A distinction is to bring regards though in associating windmill with wind turbines. Windmill has mechanical purposes and that may not include generating electricity. The wind turbines, however, are invented to harness the strength of the wind to convert energy to electricity by turning the blades of the electric-generating wind system.
It may not be necessarily that huge to construct one unless you want megawatts of electricity to power a lot of machines in many households; that situation may need a behemoth one or numerous wind turbines beautifully lined up on a road or isolated locations to bring electricity to a whole town or a district of towns. The wind turbines may be humongous but seeing them collectively in an orderly, interval set-up makes them like the 8th modern wonders. These turbines have been utilized as a gradual replacement to the fossil fuels.
However, in the case of wind turbines for domestic application, the towering machines don’t have to be that big. A certain size for home use may be installed though. But, it is also important to note how much electricity you normally consume, as this will be a factor in availing a residential wind turbine with the appropriate capacity of the system for use in homes.
There are some things to learn about residential wind turbines. Although aerogenerator can be among the best machines that help lessen the amount of smokes fumed out from the power facility, using this at home is in simultaneous fashion with procuring electricity from local power utility at the beginning. The cut-in speed of wind turbines for homes is 7-10 mph. Below that speed is not sufficient to power a home, so it is better to have another connection of wires with electric power derived from the local power utility plant.
However, when the wind speed peaks up in the location of the wind system, enabling the turbine to roll its blades faster, the energy piles up converting to electrically charged current. As the turbine’s blades move at faster rotating speed and continuously, more and more electric current is made and the electricity may be enough to power homes, thus decreasing or eventually eliminating the dependence of power from the local power retailer. There can also be the tendency that the excess power produced from the turbine can be sold to the local power utility.
Residential wind turbine is an alternative medium to obtain energy to turn into electricity to power homes. This can be used as replacement to or in conjunction with solar panels, making your home environmentally friendly. This blade-turning machine with rotor and shaft may not even require batteries to make it work. Modern residential wind system eliminates the need for batteries and this is to watch out for when opting to acquire one or a set of required wind system.
If you desire to have a set of the wind machine system that helps generate electricity in your homes, make it a point to browse around. The best deals of residential wind turbines are just here for your purchasing decision.

This website has been created to chronicle the building of my 17' diameter wind turbine.

  

Background...
In the fall of 1999 I moved to a rural area of West Virginia, named Terra Alta (high earth). To be honest we live at the *top* of Terra Alta, our house is at an altitude of 3000' where we have a panoramic view of about 270 degrees for up to50 miles!

Besides the wonderful view we also have wind, lots of wind!

So why not harness some of this to generate our own electrical power?

Typically I research the heck out of stuff, and this project is no exception! There is one website that I have found to be *the most* informative site (OtherPower). I have decided to build a wind turbine that closely resembles their 17' diameter unit, the main changes that I will be making is some slight modifications to 'beef' up the metal structure in a couple of places, otherwise it will be the same. This turbine is of the axial flux design. I want to output 2-3kwh in a 20mph wind and have found that this one should suit my needs.

Post note: they have redesigned and rebuilt their 17' turbine and it now is capable of putting more power! The structure of it closely resembles their larger 20' wind turbine.

Some good informative reading "The Bottom Line About Wind Turbines", this is a good place to start out to help you determine if a wind turbine would suit your needs.

Commercial Possibilities...
There are more and more commercial business that are involved with 'green' power'. If you have any doubts in your abilities to make your own wind turbine then either seek out a workshop (the guys at OtherPower.com have them) or purchase a commercially available unit. Many wind turbines are now available that output anywhere between 400-3.5kwh, with price and size being the major differences.

Roll your own...
I made the choice to make my own wind turbine. There were a number of factors that influenced this decision: 1) I have the skill sets 2) I have the tools 3) I have the desire 4) No tax incentives are in place to entice me into purchasing a commercial unit.
The fourth reason was probably the major item that helped me with my decision. For the type of power output that I was desiring the average cost for a commercially manufactured was between $6,000-8,000. I knew that for under $1,500 I could purchase all the items and build my own. Had there been federal/state tax credits that would have helped offset the initial investment, I would have gone that route.
The tower is another matter - I will not be building my own and am currently searching for a suitably strong - hopefully guy less free-standing tower, either monopole or lattice design. What money I save in the wind turbine will help offset the tower costs.
Disclaimer..
I am not a structural nor design engineer, the methods, tools, diagrams used/shown/discussed within this website are what I used building my own wind turbine, and as such warranty nothing. Use your own common sense when building yours and if in doubt see a professional.
It's Flying - Some Pictures..
After all of my hard work the wind turbine is on top of the tower and operational.
Click on a picture to see larger image: