Wind Turbines

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Domestic wind turbines are basically small windmills that power small generators (dynamos). If you live in a windy spot turbines are the bee’s knees, the cajones del perro or, put another way, good at making electricity.

In the UK we have 40% of the total wind energy for the whole of Europe, meaning that it’s pretty breezy hereabouts. That said, it is only possible to make use of it if you are in an exposed location, otherwise the surrounding trees and houses will disrupt the wind flow and leave the turbine floundering.

Generally it is best if your house is in an area with an average wind speed of 6m/s (metres per second), but some turbines such as the Proven Energy ones can produce a good amount of electricity in lower winds (the Proven 2.5, for instance, can produce around 4,000 kWh in a clear location with an average 5m/s wind). Many turbines do not work at all below about 3m/s, which equates to about 6.5 miles per hour.

The figures work like this:

• The average electricity used in a year by a three bed house is 5000kWh (kilowatt hours).
• Standard domestic turbines usually produce between 1kw (kilowatt) and 6kW of electricity at full stretch, which most turbines can achieve in a reasonable breeze - gales not required.
• The 1kW turbine would therefore have to run at full output for 5000 hours to generate enough electricity to power the mythical three bed house for a whole year. The 6kW turbine would have to run for only 833 hours, or continuously for about 1 month.
• The mythical house, located in a decently windy spot, would need a 2kW or 3kW turbine system to provide all of its electricity (excluding heating).

The only problem is that it is surprisingly windless over much of the country much of the time, which is largely due to hills, trees and buildings getting in the way. The DTI have a database of average wind speed around the UK, which can be found here . This will help you get some idea whether or not a turbine is a serious proposition for where you live, but the quoted wind speeds are rather optimistic, with the figures for the lowest level (10m above ground) being the least accurate. 

The higher above the ground one goes, the windier it gets.  The most productive systems therefore use long poles to hoist their turbines high into the air. This adds to the cost and does nothing for the look of a place, so for many domestic applications it may be better to use short poles or to mount the turbine on the house.

House-mounted turbines tend to be small, around the 1kW mark, and cost from around £1,500 installed. Unfortunately, they usually don't work. Pole-mounted options tend to be larger, in the 2.5kW to 6kW range and cost upwards of £10,000 to install with all the trimmings. The trimmings will include the pole (amazing, isn’t it?), an inverter to convert the DC electricity made by the turbine into AC for use by normal appliances, a battery system to store excess production in high wind/low use times, and installation.

The grant system for installing turbines is now the Feed In Tariff (FIT), which will pay you about 26p for every kWh you produce & use.  Assuming you generate only the 5,000 kWh that you as an average household use each year, and that you heat with natural gas or something similar, then you will save youself £400 in bills & get given £1,300 in FIT. This means you will net £1,700 for something that cost you £10,000 in the first place, giving you a return of about 17%.

Payback times are often around the 5 to 10 year mark, but the more electricity you produce the cheaper it will get, so the larger turbines tend to have shorter paybacks than the smaller ones.

Batteries are not necessary when a house is connected to the national grid. Any spare electricity can be sold back to the grid as it is generated, with any later shortfall met by buying in more when it’s needed. This bags you an extra 3p per kWh FIT and saves the purchase and maintenance costs of the battery module, although fairly smart electricity meters will be needed to measure purchase/sale quantities, sort out billing etc.

Scottish & Southern were buying electricity from wind turbines at 12p/kWh in late 2008 and early 2009, as long as they act as your agent for getting your Renewable Obligation Certificate allowances. This may have gone up in mid 2009, as their solar buy-price went up then, but when we rang SSE their staff were not entirely sure what they were paying for what.

Turbines can have a lifespan of up to 30 years, but require service checks every few years to ensure they work efficiently. Typical battery life is around 6-10 years, depending on the type, so batteries may have to be replaced at some point in the system's life; again, this can be circumvented by buying/selling electricity to the national connection.

Turbines mounted on a house will probably not require planning permission, but those on poles may need to be agreed by the local council. You may need to sweet-talk the neighbours a bit too. However, it is always a good idea to check with your local council Planning Department first, as each council conforms to its own charming variety of insanity.

Some examples of turbine people are given below.

Proven Energy make their own turbines, which are pole-mounted and range from 2.5kW to 15kW, with the lower powered turbines sitting on house-high poles to make planning consent easier and reduce visual impact. The turbines are robust, operate through a large range of wind conditions and are low noise. Pretty good, really, but no prices given on their site. If you are interested, you need to drop them a line and they will call you back to chat through the whole process.

Wind Trap provide small turbines of a fairly cheap and cheerless nature, but if price is a major factor and you are happy with the ‘no frills’ approach, then this could well be for you. Very DIY friendly for the smaller turbine packages, that can be house-mounted, but may be more appropriate for caravans or boats.

Energy & Environment Ltd are my personal favourites, as they have a very ‘techy’ website which is packed full of stuff and all with prices on show. It gives a great feeling of being given the whole picture with no sales tricks. The prices and products look good, too.

Alternatively, you can do a regional search for certified microgeneration installers at greenbook. They also have lists of certified microgeneration products.

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