Wind has huge potential for affordable, large-scale energy generation through onshore and offshore wind farms.
At a domestic level, things are less clear. Whether wind is right for you will depend on your location and circumstances. If you have a clear site for the turbine, away from obstructions, with high average wind speeds, then it’s worth investigating.
- wind turbines are mounted either on a building or, preferably, on a mast fixed to the ground
- the wind rotates the blades of the turbine
- which turns a rotor shaft
- which generates low voltage DC (direct current) electricity.
- an inverter then converts it to AC (alternating current or mains type) electricity to be used in the home.
Turbines can also power batteries, and to get the most from the system, you can programme it to divert electricity to other uses such as water or space heating if the batteries are full.
If you are connected to the mains grid, then when you generate more electricity than you use, you can sell the excess to your supplier. When you are not generating enough to cover your needs, you can buy electricity from your supplier.
Advantages
- reduce your carbon footprint
- reduce energy bills
- be more self sufficient
- some financial return
The success of wind power depends totally on the suitability of your site.
The key factors are:
- an average wind speed of at least 5 or 6 m/s (metres per second).
- no obstacles nearby which might reduce the wind speed or create turbulence. These include buildings, trees or hills. An ideal site is a smooth hill top with a clear, open stretch to the prevailing wind.
- you are able to connect the turbine to your property and to the national grid.
Turbines can either be mounted on a free-standing tower (normally about 5-6kW in size), or fixed to the roof of a building (micro turbines, around 1-2kW in size).
Wind speeds increase with height, so it is generally considered best to put your turbine on a mast. A small increase in the wind speed will lead to a proportionally much larger increase in the amount of electricity generated (the change is cubed – so twice the wind speed will lead to eight times as much power; half the wind speed will generate an eighth as much). A tower also helps avoid turbulence caused by trees or buildings.
Energy Saving Trust field trials found that no building-mounted turbine performed as well as expected, and where micro turbines are viable, people would be better off going for larger systems. Wind turbines are generally not suitable in urban or suburban settings. In addition to issues with turbulence for building mounted turbines, there can also be issues around vibration and potentially noise.
Noise: data on noise is generally available from the manufacturer. It is measured in decibels per wind speed. For example, the Proven 6kW wind turbine creates a noise of 45dB at a windspeed of 5m/s and 65 dB at 20m/s. This compares with whispering, or leaves rustling (30dB) or the noise of city centre traffic 95dB.
There are two measures of performance for wind turbines: a power rating and the energy output for the turbine. The latter, which is measured in kWh (kilowatt hours, the unit that electricity is measured in), is the most significant.
However, it’s no good having a high-power rating if the turbine needs hurricane strength winds to turn it and it stands idle a good deal of the time. So, while these figures can indicate comparative performance of turbines, the actual performance depends entirely on the conditions at your site.
Turbine life is up to 20 years. They need servicing every few years and you may also need to replace the inverter within the lifespan of the turbine.
Battery life is shorter; about six to 10 years. You may also have a back-up generator which needs maintaining.
Micro turbines, which are generally in the range of 500w to 2.5kW, will cost around £2,000 upwards installed according to the Energy Saving Trust.
Small turbines, ranging in size from 2.5kW to 8kW, are a much heftier investment. Prices are likely to be anything from £11,000 upwards.
The size you choose will depend on your site, the amount of power you want to generate and how much you want to spend. Connecting to the grid is expensive, and probably won’t be worth it for less than a 2kW turbine.
There are permitted development rights for (a very small number of) small wind turbines.
You should contact your local planning department for permission to install in most cases.
They will be looking at the visual impact, noise, vibration, electrical interference (with TV aerials) and safety when making a decision.
If you want to install a building mounted turbine building regulations will normally apply to size, weight and force exerted on the mounting points. They also apply to the electrical installation work.
The Smart Export Guarantee (SEG) means you can get paid for the surplus energy your Wind turbine generates and exports back to the grid. You should shop around for the best SEG tariff.
