What are small-scale wind turbines?
Wind turbines can be used to provide energy on varying scales from systems providing a few hundred watts of power used for use charging batteries, to the large turbines found in wind farms that can generate electricity for whole communities.
The technology
All wind turbines convert the power of the wind into electricity. The most common design consists of 3 blades which use the ‘lift forces’ of the wind to drive a generator, either directly or using a gearbox (it is unlikely that systems under 10kW will require a gearbox).
Wind power is proportional to the wind speed cubed, meaning that a small increase in wind speed actually results in a much larger change in the potential output of a wind turbine. Small-scale wind turbines are particularly suitable for areas of the District that are remote and not on the grid, especially where traditional energy supply is expensive or not possible.
Most small-scale wind turbines generate DC (direct current) electricity so households that are not on the electricity grid will need to use storage batteries and an inverter, which changes the DC supply into 'mains' electricity (AC supply). Small-scale turbines can also be successfully installed in properties with a mains electricity supply. An inverter is installed as part of the system, which is capable of converting from DC to a supply suitable for the mains grid. With this type of system there is no need to use batteries for storage.
To install a turbine which will cover most of your energy needs a typical property would need a system with a power output of between 2.5 and 6 kW, depending on the location of your home (and the location of the turbine).
There has been a big leap in the development of small-scale wind turbines over the last 12 months. In addition to the turbines mounted on a mast or tower, building-integrated wind turbines suitable for urban locations have now been developed and approved by Low Carbon Buildings Programme. Building integrated turbines may be vertical, as well as the traditional horizontal style. If mounted on a tower or mast they may project between 2m and 6m above the roof line and it is estimated that this type of turbine can produce 1300 – 2500 kW/h of energy each year.
For larger installations (above 5kW), freestanding turbines are often used. These are usually between 5-10m in height (depending on the required output) and are often secured using a concrete base and steel guy ropes. These ropes are anchored and allow the turbine to be lowered to the ground for maintenance.
Lifespan and warranty
Small-scale wind turbines have a lifespan of up to 20 years, however they should be checked every few years to make sure that they are in good working order. Batteries for use in off grid systems have an average life expectancy of 6-10 years so will need to be replaced at some point in the system’s life. Some manufacturers advise that turbines installed on properties very close to the sea may have a reduced lifespan and require more regular maintenance. If you do live very close to the sea, it may be worth discussing this with the installer when they are estimating the cost of your system.
Cost
The Department of Trade and Industry currently give ‘average’ system prices as £2500 to £5000 per kW, although costs may be lower for building integrated systems.
Where in the District?
A reliable estimate of the wind speed for your property can be obtained from the Department of Trade and Industry who provide an online database of wind speeds for the entire country, calculated at 10m, 25m and 45m above ground level.
You can use this database to find the average wind speed for your area by using your postcode to generate a grid reference. It is rather a complicated process, but very useful in assessing the potential performance of a wind turbine on your property and the website contains detailed instructions on how to generate the information you need.
Using the wind speed database
In the first page of the link you are given 3 ways of accessing the database. Click option 1 (Interactive on-line), which will generate a page containing a link to convert a postcode to a grid reference; click on this option, enter your postcode (ensuring that you also click to select the postcode option) and click convert. This will bring up a page of various reference numbers. The reference that you need is the LR reference, which will start with 2 letters, followed by a series of 6 numbers (e.g. SE145225). You then need to return to the initial screen and enter this code, minus the last 2 numbers, in the box at the bottom. This will then generate the wind data for your particular area.
If you have any problems with accessing the database, please contact the Energy Officer with your postcode and contact details.
Contact Details
South Derbyshire District Council
Energy Officer
Civic Offices
Civic Way
Swadlincote
DE11 0AH
Tel: 01283 228719
email: energy@south-derbys.gov.uk
page ref: SDDC 136