Is my garden windy enough for a wind turbine?
Posted by Alex Barrett on 20 June 2016 at 10:05 am
Generating energy from a wind turbine seems like a great way to save on your energy bills. But how windy does your area need to be in order for a turbine to be viable? How do you measure wind speed and which are the windiest parts of the UK?
We have a long history of using wind turbines to power our machinery. Windmills originated in medieval times and revolutionised the amount of work it took to grind grain and do manual labour. Now we can generate electricity from a turbine and use it to do all manner of tasks. Unfortunately wind can be an intermittent source of power, even in a windy country like the UK. Not all sites are suitable for a turbine.
All wind turbines have a “cut in” wind speed. Below this the turbine might turn, but it won’t generate enough electricity to register. This is usually around 3-4 m/s, so you need to have average wind speeds of more than 5 metres per second for it to be worth your while to install a turbine [1, 2]. So, you have to plan carefully when deciding where to install one [3, 4].
It is recommended that anyone considering installing a wind turbine first gets an anemometer. This is a sensor that measures wind speeds. You should run it for several months and work out what the average wind speeds are at different times of year. You can then see whether a turbine is likely to pay off. Wind speeds increase with height, so if you can mount a turbine on a mast or tower then you will find it to be more effective. Hand held anemometers are available from around £10.
There are several online tools that use meteorological measurements to work out what the average wind speeds in your area are. These are good for getting a general idea, but unless you live right next to a weather station then there will be some estimation involved. Weather stations are quite spread out, and so measurements have to be interpolated between them. This means that the measurements at adjacent stations are used to estimate the wind speeds in between.
We found a nice calculator at Aeolus Power  which uses data from the Department of Energy and Climate Change. This has a point spacing of one kilometre, so should provide an estimate close to where you live. However local variations in topography, the position of buildings and a range of other factors can alter wind speed on the small scale. Urban areas generally have lower wind speeds than the countryside due to the proximity of large buildings. So while it is fun to see what the reported averages are for your postcode it is no substitute for making your own measurements.
It turns out that the YouGen offices aren’t in a very windy location, we’d have to build a turbine at 45 metres height in order to get 5.9 m/s winds.
So which are the windiest parts of the UK? Unsurprisingly the highlands and coastal regions are windier than the lowland and inland regions. The South East of England is much less windy than the West of England and Scotland. The Met Office have a nice map that summarises wind speeds across the UK. They report that the record for highest wind speed was 150.3 knots, around 278.4 km/hour on the summit of Cairngorm in 1986 . Although that might be a slightly inaccessible site for a wind turbine!
- Wind Power Program
- University of Nottingham (Links to pdf)
- Aeolus Power Wind Energy: Wind Speed Calculator
- Which? Magazine
- The Met office
Image Credit TechnoSpin via Flickr
More information about Wind Power on YouGen.
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