Exploiting the power in the wind is an ancient technology and old windmills form part of a picturesque landscape in parts of the country where the absence of high ground eludes the possibility of hydropower. Modern materials and research has improved the design and efficiency of wind turbines offering scope for significant amounts of renewable energy generation. The technical resource is only limited by the size and number of turbines installed. Turbines work by slowing down the wind that passes through the swept area of the blades, but the wind soon recombines and a second turbine can be installed at a distance of about 20 rotor diameters. Wind energy can only be farmed where average wind speeds are high enough and will be confined to those areas with an average wind speed of over 7m/s.

South Hams Wind Resource map (Source: Government Office for the South West)

Small-scale wind

In South Devon, most of the suitable wind resource capture areas coincide with areas of outstanding natural beauty and Dartmoor National Park. Countryside Character Assessments indicate that South Devon has a moderate sensitivity to large-scale wind turbines and suggests that “for the purposes of this strategic setting exercise, large clusters of turbines have been discounted for reasons of landform scale. Because of the wide views across this incised plateau, consideration should be given to the spacing of turbine clusters to avoid inter-visibility or ‘visual clutter’.” Modern near silent wind turbines have been developed to be mounted like a TV aerial on rooftops, and there are also a wide range of intermediate sized ones for use on farmsteads and boats.

More realistic than roof mounted turbines for T&D, would be a small number of 5-6 kW machines on 12-15m poles for suitable farms and houses with adequate wind resource (of which there are several in S.Hams)¹. The following estimate is based on around 1% of all current households being agreeable /suitable for this resource.

Large Scale Turbines / Wind farms

The thorny issue of wind farms is certain to appear and reappear as conventional energy supplies decline. Opinions are often polarised about the appropriateness of large-scale wind turbines. There is no doubt that these tall structures do have an impact on the landscape, they are however the one renewable energy technology that has been developed to the point where it can deliver energy at a comparable cost to current fossil derived energy. The UK has a good wind regime and South Devon a number of areas where, Landscape Designations apart, a significant wind resource could be harnessed. From a purely wind resource perspective, any site that has an average wind speed in excess of 7.5m/s will offer an economically viable site.

Sustainable South Brent has been assessing wind speeds in their area with a view to installing a community wind turbine. They hope to install a 50 kW windmill that would carry a 27meter diameter turbine on a 30m high hub. During 2008 their wind speed measurements indicated a potential yield of 488 MW/h/y. We use their figure below in one of the estimations.

To enable a rough idea of the potential capture of energy from large scale in Totnes & District, the following combination of large-scale wind turbines are assessed:

(For information only – assessed resource based on per capita share by population in Totnes):

Offshore wind resource

Totnes and District would not have direct access to benefit for its local energy budget from offshore wind, however such a resource could feed into the grid and benefit the area indirectly. The resource captured will be constrained by the number of turbines installed and the seabed conditions for installation.

(For information only – assessed resource based on per capita share by population in Totnes):

Birds lost in action (Source: Sustainable Energy Without the Hot Air)

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