In the UK we have 40% of Europe's total wind energy, and big strides have been made in the last decade to make better use of that resource. Wind energy now accounts for around 14% of our electricity production, and is making a real contribution to cutting carbon emissions, chiefly from large onshore and offshore windfarms. The technology is reasonably simple and can be an option for a homeowner in the appropriate location, particularly where a free-standing mast can be erected.
Wind turbines use the wind to rotate aerodynamic blades that turn a rotor which creates electricity. This may supply energy for a battery, or supply electricity to the grid. Wind turbines can be free standing, mounted on a mast and located near the building(s) that will be using the electricity, or roof mounted micro-turbines, installed on the house roof.
What are the costs and savings?
Roof mounted micro-turbines cost from £1500, but their performance is highly variable and depends crucially on the nature of their location. The Energy Saving Trust has more information about microgeneration using wind turbines. Larger mast-mounted systems in the region of 2.5kW to 6kW cost between £10,000 and £30,000 installed, depending on location and the size and type of system. Electricity generated by wind turbines attracts incentive payments under the Feed-in Tariff scheme.
The electricity generated depends on the wind speed and direction. It will probably not be effective to install a domestic wind turbine unless the local annual average windspeed is at least 6 metre per second, and there are no significant nearby obstacles such as buildings, trees or hills that are likely to reduce the windspeed or increase turbulence
- Consult an installer accredited with the Microgeneration Certification Scheme to provide more detailed advice about your individual circumstances.
- Turbines can have a life of up to 20 years but require service checks every few years to ensure they work efficiently.
- Consult the local authority about planning permission
- Small scale wind power is particularly suitable for remote off grid locations where conventional methods of supply are expensive or impractical and the wind speed and direction are suitable.
- Micro-wind turbines mounted on roofs in urban locations do not provide much power and are probably the least effective renewable energy measure.
- The inverter will likely need replacing during the lifetime of the turbine, so this cost should be accounted for at the outset.
Location, Location, Location - a field trial
The Energy Saving Trust undertook a field trial of domestic wind turbines in 2007, monitoring the performance of 57 turbines installed at various UK locations. Called Location, Location, Location, its key findings were:
- Most building-mounted turbines in urban or semi-urban locations had inadequate wind speeds and performed poorly.
- Free-standing turbines in suitable sites performed well.
- Scotland contained the best locations due to higher wind speeds.
- Potential customers should ensure that products conform to the standards developed by the Microgeneration Certification Scheme.
- The government's windspeed database - called the Numerical Objective Analysis Boundary Layer (NOABL) - which was used to estimate local windspeeds, was found to significantly overestimate wind speeds. MCS accredited suppliers should use an adjustment, to give a more accurate value. The Wind Yield Estimation Tool provided by the Carbon Trust was found to be a more accurate prediction method.