Here are some of the most commonly asked questions we get about small wind energy systems.

Can I have my own wind turbine?
Wind turbines are ideal for householders, communities and small businesses to use for on-site energy generation. There are a range of different types of small wind turbine models and thanks to their flexibility small wind turbines can be installed in most locations. Your individual site specifics (such as location, wind speed and local landscape) will eventually determine the best turbine type and size for your case.

How do I find out if my site is windy enough?

There are several online resources that will provide you with wind speed estimates for your area:

The actual wind speed at your site will be influenced by the local topography and any nearby obstructions such as trees or other buildings. Wind movement around buildings themselves is very fickle, so take expert advice.

For urban areas, make sure to establish wind speeds in your area, since there are likely to be other factors affecting wind speed such as the structure and height of buildings.

How does a wind turbine make electricity?
Most wind turbines have two or three blades which face into the wind; the wind turns the blades round, this spins the shaft, which connects to a generator. A generator produces electrical energy from mechanical energy.

What size turbine will I need?
An average house uses an estimated 4,700 kilowatt hours (kWh) of electricity per year. To find out how much a wind turbine produces, go to our calculations page to see energy production and emission saving calculations. Note however, that the generation from a wind turbine and the demand in a house are not coincident. For grid-connected systems, If the wind turbine is connected to your side of the utility meter, you will use all the wind power available to meet your demand. When the wind generated power is greater than your demand, the net excess is exported to your local network.

You can consult the DSIRE database (http://dsireusa.org/) to see whether net metering facilities are available in your area.

Manufacturers will usually assess the power requirements and likely wind generation of your particular site to see which of their turbines may suit your needs. You may wish to have independent advice from a colleague, but as yet there is no general agency for this.

How tall are small wind turbines?
Tower height varies according to wind turbine models, but generally ranges from 50 to 140ft. In general, the higher the tower, the higher the average wind speed that the turbine will experience and the smoother the wind. Both of these factors will have a positive impact on wind energy generation.

How much space do I need for a turbine?
Ideally, stand-alone turbines should be sited as far away as possible from buildings or trees, which may block the wind and cause turbulence. As a guide, the wind turbine should be about twice the height of obstructions in the immediate front of it (for at least the prevailing wind direction). In general, the turbine should be above the height of nearby obstructions that are within a distance of 30 to 60ft of the tower heights.
See also our fact sheet on siting a wind turbine.

Do I need planning permission?
Small wind energy installations may require planning permission and you should always consult the planning officials, preferably confirmed in writing if this is needed. It is clearly good manners to discuss your plans and aspirations with your neighbors. Relevant factors include environmental impact, access to the site, noise and visual effects.

What are wind turbines made of?
Wind turbine towers are generally made of steel. The blades are made of glass-fiber reinforced polyester or wood-epoxy. The finish in most models is matt, to reduce reflected light.

Can I build my own wind turbine?
There is a very good book on this subject, ‘Wind Power Workshop’ by Hugh Piggott, available from the Centre for Alternative Technology. For a brief idea of what is involved see how to build your own wind turbine. However, as with all technical and potentially dangerous equipment, most people should buy commercially manufactured and professionally tested machines.

Are wind turbines noisy?
The majority of modern small wind turbines have been designed to be very quiet. Our turbine has a low constant rotational speed which greatly reduces the rotor noise to a mere ‘swooshing’ sound. In technical terms, our turbine’s noise emissions fall below 50dB at a distance of 100ft. This is comparable to the loudness of a typical conversation.

Do wind turbines affect radar systems or TV reception?
Small wind turbines are unlikely to have any detrimental effects on aviation and associated radar or navigation systems. In general, turbines with small diameters are unlikely to have effects on television and radio reception. If this occurs it is likely to be highly localized and technically easy to overcome. It is also unlikely that small rooftop wind turbines will effect either mobile phone reception or fixed radio or microwave communications links.

Will small wind turbines have a ‘flicker’ from the turbine blades?
Potentially, sunlight passing through moving blades can cause a flickering effect in ‘line of sight’ directions. The possibility of the shadow from the wind turbine causing flicker should be considered at the site selection stage. It is normally possible to avoid this problem. Reflections from the blades are unlikely, especially as the coatings used on modern turbines have been selected to minimize reflection.

What about lightning strikes?
Lightning strikes do occur and can cause damage to any structure raised from the ground. However, lightning protection is a well known practice and can be applied to wind turbines as for other equipment. On some turbine models, full protection of electrical circuits is installed at manufacture. Obviously, as with other elevated structures, protection against lightning is advisable if the turbine is installed in an area where lightning strikes are frequent. Insuring the turbine against lightning damage may be a wise precaution.

Can I use my turbine for heating?
The simple answer is yes, small wind turbines can be used for direct heating, e.g. water heating as well as for battery charging and they are also ideal in remote off-grid locations. However, the energy required to heat a building is usually significantly more than the energy used in electricity, so a much larger turbine would be needed for building heat.

How much of the time do wind turbines produce electricity?
A modern wind turbine produces electricity 70-85% of the time, but it generates different outputs dependent on wind speed. Over the course of a year, a small wind turbine in the UK will generate about 20% to 30% of the amount it would generate in a constant strong wind. This is known as its ‘load factor’ (or ‘capacity factor’). The turbine itself has usually at least 97% mechanical availability and generates with 95% mechanical to electrical efficiency, so the limited output is overwhelmingly associated with lack of wind The load factor of conventional UK thermal power stations is on average 50%, and the mechanical to electrical efficiency is between 30% and 50% depending on the type of plant.

What happens when the wind stops blowing?
When the wind stops blowing, electricity continues to be provided by other forms of generation in an isolated system (e.g. batteries, diesel generator) and, as in our case, by the grid in a grid-connected system.

Can I get a grant for my wind turbine?
Gaia-Wind turbines qualify for the federal Small Wind Investment Tax Credit (ITC), which provides tax credits of up to 30% of the total project costs. Non-residential customers also have the option to receive an up-front cash grant instead.

In addition, Gaia-Wind turbines qualify for grant assistance under the following state incentive programs:

NYSERDA PON 1098 (NY) - http://www.powernaturally.org/programs/wind/incentives.asp
Focus on Energy (WI) - http://focusonenergy.com/Incentives/
Clean Energy Program (NJ) - http://njcleanenergy.com/renewable-energy/programs/renewable-energy-incentive-program

Applications to other incentive programs are currently in progress.

Isn’t it cheaper to save electricity?
Since most of us are not fully efficient in using energy, it is almost certainly cheaper to reduce electricity consumption than to buy it or generate oneself. The latest information on how much it costs to save electricity is available from the Energy Savings Trust. Nevertheless, electricity generation is necessary. Therefore, to combat climate change and to have security, it is essential both to increase the proportion of renewable energy and also to have energy efficiency.

How do I look after my wind turbine?
The maintenance required for small wind turbines is likely to be minimal. An annual check is all that is likely to be required and can be arranged by the wind turbine manufacturer.

How long do wind turbines last?
A wind turbine typically lasts around 20 years. During this time, some parts may need replacing. The very first factory-mass-produced turbine celebrated its 21st birthday in May 2001 and has operated steadily throughout its lifetime, and so far, none of the major components have had to be replaced. Some earlier workshop-produced turbines have operated for longer.

What are the advantages of Horizontal Axis Wind Turbines?
- Variable blade pitch, which gives the turbine blades the optimum angle of attack. Allowing the angle of attack to be remotely adjusted gives greater control, so the turbine collects the maximum amount of wind energy for the time of day and season.
- The tall tower base allows access to stronger wind in sites with wind shear. In some wind shear sites, every ten meters up, the wind speed can increase by 20% and the power output by 34%.
- High efficiency, since the blades always move perpendicularly to the wind, receiving power through the whole rotation. In contrast, all vertical axis wind turbines, and most proposed airborne wind turbine designs, involve various types of reciprocating actions, requiring airfoil surfaces to backtrack against the wind for part of the cycle. Backtracking against the wind leads to inherently lower efficiency.

What are the disadvantages of Horizontal Axis Wind Turbines?
- Taller masts and blades are more difficult to transport and install. Transportation and installation can now cost 20% of equipment costs.
- Stronger tower construction is required to support the heavy blades, gearbox, and generator.
- Reflections from tall HAWTs may affect side lobes of radar installations creating signal clutter, although filtering can suppress it.
- Mast height can make them obtrusively visible across large areas, disrupting the appearance of the landscape and sometimes creating local opposition.
- Downwind variants suffer from fatigue and structural failure caused by turbulence when a blade passes through the tower’s wind shadow (for this reason, the majority of HAWTs use an upwind design, with the rotor facing the wind in front of the tower).
- They require an additional yaw control mechanism to turn the blades toward the wind.

What are Cyclic Stresses and Vibrations?
Cyclic stresses fatigue the blade, axle and bearing; material failures were a major cause of turbine failure for many years. Because wind velocity often increases at higher altitudes, the backward force and torque on a horizontal-axis wind turbine (HAWT) blade peaks as it turns through the highest point in its circle. The tower hinders the airflow at the lowest point in the circle, which produces a local dip in force and torque. These effects produce a cyclic twist on the main bearings of a HAWT. The combined twist is worst in machines with an even number of blades, where one is straight up when another is straight down. To improve reliability, teetering hubs have been used which allow the main shaft to rock through a few degrees, so that the main bearings do not have to resist the torque peaks.

When the turbine turns to face the wind, the rotating blades act like a gyroscope. As it pivots, gyroscopic precession tries to twist the turbine into a forward or backward somersault. For each blade on a wind generator’s turbine, precessive force is at a minimum when the blade is horizontal and at a maximum when the blade is vertical. This cyclic twisting can quickly fatigue and crack the blade roots, hub and axle of the turbines.








Wind Turbine