For the individual self builder, wind energy will seldom be a viable choice especially in an urban area. This is because the payback time on a wind generator depends on there being an ample supply of wind and a situation for the generator in which it can receive an unobstructed flow of wind from any direction.
‘Ample wind’ means the sort of place where there are few lulls in the wind, ideally you have to lean into it 24/7 for most of the year. ‘Unobstructed’ ideally means no buildings, or woods nearby and situated on top of a hill. Probably one of the worst places for a wind generator is attached to your gable end or chimney in town. There is constant turbulence around the roof of a house, cities are usually more sheltered and the noise[for the purposes of part C of the Approved Documents] - Noise is unwanted sound. and vibration is likely to be substantial. See Building for a Future – page 48. Very often the money would be better invested in higher levels of insulation and air tightness. The PassivhausSee more on the Passivhaus standard. The PassivHaus Institute has pioneered a standard for low energy buildings. It includes very low energy usage and ways of achieving this. The word is derived from the idea of buildings which are fundamentally low energy and passive solar heated rather than using extra gadgets to heat them. See Passivhaus for the UK branch of the organisation. approach to house design concentrates on “fabric first’ and then add-on technologies may come later.
See also Small scale wind turbines 1 – 6kW on the Greenspec web site
An excellent report, the Encraft Warwick Wind Trials Project, has recently been published on trials of 26 small scale wind generation installations. It shows the huge discrepancy between predicted energy output and what was actually achieved. The difference was mainly due to inaccuracies in wind speed prediction but manufacturers claims for their generators’ power curves was also to blame.
The Energy Savings Trust has a lot of information on generation of renewables.
One of the reasons why electrical generation from wind energy might be if you are off grid and have no other means of generating electricity. One of the companies specializing in design and supply of off grid systems is Energy Development Cooperative Limited. (and their shop).
Another reason for using wind power might be if you regularly need to pump quantities of water around. Going back through history it has worked well to use wind whenever it was available for this purpose. It’s usually a win-win situation as backup pumps can be used when wind is not available.
There are also developments in the pipeline for a more integrated approach to domestic generation in the form of Power Collective’s Ridgblade. This is a horizontal cylinder turbine mounted along the ridge of a building’s roof. This should be worth keeping an eye on. Vertical axis turbines are able to use wind from any direction without having to adjust and they tend to be quieter in operation. See the recent BSIBritish Standards Institute award winning design by Ben Storan.
However, if you do live in a windy spot and you have space to erect a tower, it may be worth getting a survey done by a specialist company such as Sun and Wind. This may involve them setting up an anemometer to measure the wind speed for a year to make sure it is worth while. Neighbours can be hostile to proposed wind generators at the town planning stage.
Community wind power
This can indeed be a profitable option. An interesting example is the village of Fintry in Sterlingshire where they have invested in a large generator and are ploughing the income from it back into improving the insulation of the local housing. See the heraldscotland article
The Findhorn FoundationThe Findhorn Foundation is a large community near Inverness. There is a strong emphasis on sustainable building and living. at Fores has 4 large wind generators which supply all of the community’s needs with surplus electricity exported into the grid
Another interesting community based wind project is at the Hockerton Housing earth sheltered housing development. They have an online video explaining the process they went through for installing a 225 kWkilowatt - a measure of how fast energy is flowing. e.g. electricity might flow through an electric kettle at the rate of 2 kW second hand wind turbine as part of a Hockerton village initiative for green energy. They also have information showing capital cost and power output from solar panels and 2 smaller wind generators (5kW and 6kW) which were installed at the earth sheltered housing project. This sort of hard information is very welcome because it is actually quite difficult to get hold of. Most times the figures you see quoted are manufacturer’s ‘ideal’ figures or some one’s ‘hopeful’ projections or else the figures get messed up by breakdowns, changes and incomplete logging.
Having been so negative about small scale generation it is best to say that there are some excellent small scale generators around. See, for instance, Wind and Sun’s examples. Also, there is the added factor of the feedin tariff which has recently become available.