‘Microwind’ or ‘small-wind’ turbines
40% of the wind energy blowing over Europe blows over the UK so it should be possible to generate electricity with a small-scale wind turbine for the home system installed on your roof, or on some other spot on your land. A small scale wind turbine for the home system installed on an exposed site should be able to generate more electricity that you can use.
There are two types of wind turbines for the home.
- free standing turbines (typically 5kW to 6kW) mounted on poles erected in a suitably exposed position,
Pole Mounted Wind Turbines for the home
- and smaller, (1kW to 2kW) building and mast mounted systems placed on the roof.
Roof Mounted Wind Turbine for the Home
The electricity that you don’t use can (except in Northern Ireland), be sold into the National Gridand you receive payment in the form of a ‘feed in tariff’. The payments have reduced recently so it means that any proposed wind turbine for the home system must be subjected to careful scrutiny to ensure that it’s economically viable. If the turbine is ‘off grid’ (not connected to the local electricity grid), unused electricity can be stored in a battery and used when needed.
The installation firm and the wind turbine design itself must be certified under the Microgeneration Certification Scheme (MCS).
Benefits of Wind Turbines for the Home
- wind is free so once the installation costs are paid all that remains is the occasional maintenance. Modern wind turbines for the home require very little regular maintenance
- if your property is not connected to the National Grid (a distinct possibility in the windiest areas) you can store the electricity in batteries and use it when it’s needed
- wind electricity is ‘green’ renewable energy, releases no harmful pollutants and emits no carbon
- planning consent is not usually required in England (permission is required in Scotland)
Possible Drawbacks of wind turbines for the home
- wind turbines for the home have become controversial in many locations especially in National Parks
- they are vulnerable to wind turbulence so require careful placement. Successful placement is usually difficult or impossible in urban locations
- although small scale wind turbines for the home are nothing like as noisy as the big industrial turbines located in the countryside, they can still generate enough noise and vibration to disturb the occupants of the property
- wind turbines for the home are not popular with serious environmentalists. Although they generate carbon free electricity, they nevertheless still have to be manufactured, delivered and installed etc and those processes are all carbon generating activities
- a building mounted wind turbine for the home installation can add stress to the building owing to the vibration. Professional guidance should always be sought
- wind turbine for the home installations cost significantly more than solar panels and are rarely (if ever) viable in purely financial terms in an urban or suburban environment
However if properly sited a wind turbine for the home installation might still generate a reliable supply of electricity during the day and night and there is no reason why a roof based system should not also incorporate solar panels. There is a partial (although not an entirely reliable) inverse relationship between the months in the year in which wind power is most readily available and the months in which the sun shines.
A dual wind turbine for the home and solar panel system can generate ‘feed in tariff’ electricity from both sources throughout the year and some initial cost economies are gained by installing two systems at the same time.
Costs of wind turbines for the home
The evidence is starting to mount against wind turbines for the home in urban and suburban areas. ‘Which’ has experimented with its own test installations and the results have been poor. The Carbon Trust has reached the conclusion that in some cases the carbon emissions avoided by the turbine will not make up for the carbon emissions caused in it’s manufacture.
The Energy Saving Trust (EST) organised its own test of 38 turbines mounted on buildings and the results were terrible. They found that no urban or suburban site generated more than 200kWh of electricity a year, a saving of £26 for the best. Some systems even consumed more electricity than they generated.
The cost of a wind turbine for the home system will depend on its size and what’s involved in installing it. A turbine mounted on a building, costs less than one mounted on a pole.
- a 1kw wind turbine for the home mounted on a roof costs about £2,000
- a 2.5kW turbine mounted on a poll costs about £15,000
But in all cases the cost per kilowatt falls considerably with each additional kilowatt.
The government’s ‘Green Deal’ may be able to help with the installation costs. KCS will be publishing a feature on the scheme itself shortly. The facts are however that in purely economic terms even a successful system is only marginally viable at best. The pay back time is very close to the lifespan of the wind turbine for the home system itself leaving no margin to pay for the financing costs
Savings and income from wind turbines for the home
Turbines mounted on buildings tend. As a rule to produce less electricity per kilowatt than pole-mounted ones. A 6kW turbine on a good site can generate some 10,000kWh, the equivalent of over five tonnes of carbon dioxide a year.
The electricity supply company pays a ‘Feed-in Tariff’ for each kWh of electricity generated and a lower tariff per kWh for electricity you ‘export’, i.e. put back into the grid. It credits these sums against the consumption in your home charged at their usual rate and pays you the difference if you generate more than you consume. At the moment the scheme is not available in Northern Ireland. The Energy Saving Trust publishes the latest feed in tariffs. KCS does not reproduce them here as they are liable to change.
Siting of wind turbines for the home
The viability of a wind turbines for the home system is almost entirely dependent on siting and that is the system’s greatest weakness. It may well be possible to site industrial sized turbines on the top of a hill where there are no buildings nearby but very few houses are so favourably located. Readers may like to consider our diagram below. Most houses and even blocks of flats fall within the ‘Bad Site’ Definition
Even a site which appears (and is) very windy may not have ‘the right sort of wind’. The success of the system depends on quality and quantity of wind at hub height and the direction of the prevailing winds at any given time. Obstacles (even some distance away) cause turbulence. Very careful observation is required over a period of time and in some locations it may not even be possible to make a close estimate of the efficiency of a system until it has been up and working for up to two years.