Ourpower Guides - Wind - Detail

Proven 6The UK has over 40% of Europe's wind but this potential free and clean energy remains largely unused.
However, wind farms are becoming more common sights, as are the smaller windmills, or turbines as they are now known, that can be installed by homeowners and small businesses.

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Small wind turbines are used to:

• Generate electricity to charge batteries for your caravan, boat or remote building (being off-grid, i.e. not connected to the national power grid)
• Generate electricity for your house to reduce the amount of electricity you buy (an on-grid system)

How Wind Turbines work?

Moving air turns a wind turbine, and transfers this energy into a spinning shaft, which usually turns an alternator or generator to produce electricity. The amount of power that's available depends on both the wind speed and the diameter (width) of the turbine's blades (its swept area).
A turbine can be considered the opposite of an electric fan that uses electricity to turn and blow wind towards you.
For a system connected to the grid (on-grid), an inverter and controller converts the DC electricity generated to AC, at 240V for use in the home, or at higher voltages for export to the grid. Batteries are needed for off-grid systems.
Wind speed and the specific location of the turbine are very important factors.

The benefits - why install?

• Wind produced electricity is clean and produces no CO2 or waste products. It utilizes a plentiful resource in the UK.
• All the electricity produced reduces the need for electricity to be produced centrally, often by inefficient and polluting methods.
• The value of your home will be enhanced by a an installed wind turbine. The arrival of Energy Performance Certificates will reinforce this.
• With planning permission becoming easier to achieve (or not needed at all through 'permitted development'), if your site is suitable, installing a wind turbine can be effective.

Is it suitable for my home?

Factors that need to be considered are typically:

• Wind speed at your specific location is the main factor, with possible returns increasingly rapidly at windier and more exposed sites. A national database of wind speeds by location can be a good starting point. But this only gives an indication, with local factors being also very important.
  o Height of the turbine above ground. Ideally, the turbine will be 9m above any obstacle within 100m upwind.
  o Proximity of obstructions (such as trees or buildings) in the direction that the wind usually comes from. These can slow or block the wind, and also cause turbulence that affects the efficiency of the turbine. An exposed hilltop with little or no surrounding trees or buildings would be an ideal spot.
• Ideally, a wind speed meter (anemometer) can be used on site for a number of months to measure the average wind available. Where this is not practical, an expert installer will provide a 'resource assessment' of your site.
• A turbine positioned on its own mast is always best and allows larger turbines to be fitted. Small turbines cost considerably more per kilowatt of electricity produced than larger ones. An alternative is to fit the turbine to your house.
• Turbines attached to houses in towns can be effective, but are often badly affected by turbulence caused by surrounding buildings.
• Planning issues often concern visual impact, noise and listed buildings or conservation areas. However, the design of turbines is improving to reduce noise, and planners are typically becoming more knowledgeable and inclined towards approval.

An accredited installer or supplier will help you plan the best system for your circumstances and budget.

Different sizes of turbine

A typical UK home may use around 3,500 kilowatt hours of electricity per year. As with all microgeneration, initially make sure that your house is as efficient as possible by installing insulation, low-energy light bulbs.
There are a variety of different sizes and models of small/micro wind systems. These range from 100 watts for very small systems that are less than 1 metre in diameter, and typically used to charge 12 V or 24 V batteries in stand-alone systems such as boats. Individual houses and businesses would usually use turbines ranging from 0.6 to 20 kilowatts, with models marketed as potentially suitable for rooftops varying from 0.5 to 2.5 kilowatts in size.

Typically a 1 kilowatt rated turbine in a good site with average wind speed of 5m/s may produce about 1,200 kilowatt hours per year. For an average home in a good location to produce all or most of its power, a turbine rated at 2.5 to 6 kilowatt may be suitable.

Care should be taken on interpreting the 'rating' of a turbine. It typically indicates maximum power generated at a wind speed of about 12 m/s. Even very good sites would not expect to achieve 30% of this potential over a year.

Connecting to the grid

Selling excess power produced is becoming easier, with plenty of advances expected in the future.
Households can connect to the grid through their fuse box (and if an export meter is bought for about £100) any excess electricity, being produced at any time, can be sold to your electricity provider.
The price paid is still typically less than you might pay for electricity, but opportunities are improving all the time as more and more people sell their power.
Additionally, Renewable Obligation Certificates (ROCs) are available for every megawatt hour of electricity produced per year. Increasingly there are options for electricity companies to deal with the complexity of ROCs and offer a combined electricity and ROCs package to householders.

Installation, maintenance and costs

Small/micro wind systems range in cost from a few hundred pounds for a small battery charging system, to several thousand pounds for a larger system capable of meeting electricity needs for an entire household or business. A turbine rated at 600 watts - 1.5 kilowatts might cost between £1,500- 3,000, whilst turbines rated at 2.5 to 20 kilowatts can cost between £6,500 and £20,000. The amount of money a wind turbine will save you depends on the amount of initial capital outlay, electricity prices and how much electricity your turbine produces.

Once a small/micro wind turbine has produced enough electricity to pay for its cost, it will then start to save you money. A turbine on a good windy site will pay for itself more quickly and start to generate free electricity sooner than on a poor site.

Grants are available from the Low Carbon Buildings Programme. Currently up to £1,000 per kilowatt (or to £2,500/30% of total cost maximum) is available for wind turbine installations.

Turbines typically have a life of up to 20 years, but should be checked every few years for efficient running. Batteries (if needed) will typically last less than 10 years.

Where can I find out more?
The DTI funded low carbon buildings programme provides grants to help with the costs of installing wind turbine.
To be eligible for a grant you will need to use a certified installer and products.
Or visit the following sites:

Visit: Energy Saving Trust

Visit: Centre for Alternative Energy

Visit: The British Wind Energy Association

Look for Ourpower Pioneers in the Ourpower Community who have fitted Wind Turbine systems near you so you can ask and read about their experiences. Then use the Ourpower Directory to find local installers and suppliers - reading about what they can offer and what they have done, before asking a number to consider your situation and to quote. Always, get at least 2 quotes - more if possible.

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