How can I find out if I live in an area which might be suitable for harnessing the wind?

Commercial wind farms use expensive calibrated wind measuring devices (anemometers) and data loggers to measure actual wind speeds for at least 12 months, combined with Met Éireann data over a number of years, before committing to developing a site. This type of wind study is not a viable option for small scale customers as it would increase the cost of the project disproportionately. But there are companies who will carry out a scaled down version of such a study for customers. These companies are often independent and provide a report to their customers which can be presented to suppliers of the turbines.

Opting to use a non-calibrated anemometer for such a study may not give you any more accurate information than might be gleaned by a trained and competent site assessor. The power in the wind is proportional to the cube of the wind speed so an inaccurate wind speed measuring device can lead to a large error in estimating power output. An error of 10% in the wind measurement leads to a 33% error in estimating power output.

If you have access to the internet the first port of call could be the wind atlas on the SEAI website. A CD-Rom of the wind atlas can be purchased from SEAI REIO's online bookshop. Using the CD and free trial GIS software from Pitney Bowes it is possible to estimate average wind speeds for your location by inputting GPS or grid co-ordinates. Wind speed and thus the power in the wind in your location is the single most important factor in the viability of a wind turbine. The wind atlas will only be able to show you if your area is windy or not when compared to other areas in Ireland. The lowest height currently available on the wind atlas is 50m above ground level and the speed at domestic and small commercial turbine heights of the range of 10-20m would be considerably less. The wind atlas will not give you an accurate estimate for the wind speed at small scale heights because local and ground conditions impact greatly on wind speed. A site assessor can use mathematics to estimate the wind speeds at the height of a turbine using the wind speed reading at 50m but the actual wind speeds could vary greatly due to obstructions and topography.

A site visit by a trained, competent site assessor should be part of the service provided by turbine suppliers and installers. It is not possible to assess a site fully by using the SEAI wind atlas alone or in combination with Google Earth or aerial pictures. Being on the ground is the only means by which a full appreciation of the site's suitability and viability for a micro wind turbine can be estimated. The turbine supplier may charge a fee for the site assessment to cover their travel expenses and time. This fee may be subtracted from the price of the turbine should the sale be completed.

It is impossible to predict exactly the average wind speed and thus the output of a wind turbine at a given site. However, with a thorough resource assessment, site assessment and independent test reports for the turbine it is possible to estimate a range within which the turbine should be expected to perform.