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Assessing your Project

Frequently asked questions by landowners and farmers regarding how to assess your wind turbine project

What is Distributed Generation?

Most wind farms have been developed by large utility companies or specialist developers, using teams of experts. Wind farms generally consist of many turbines using the largest sizes possible and connected into the heart of the power grid. Because of the large investment these are likely to be owned by the power utilities or specialist investment funds.

Distributed Generation is different in all respects. With increasing maturity of turbines and the supporting services it is now commonplace for farmers, other landowners, businesses and community groups to install their own turbines. These might be singles or small clusters, sized to suit the location and funds available.  They are connected into the extremities of the distribution network perhaps through an existing grid connection. With values closer to farm equipment or buildings, these are more likely to financed by local people so that the full value of the project stays in the community.

What is the Feed in Tariff?

The Feed In Tariff (FIT) is a recent scheme introduced to support Distributed Generation from renewables sources. For wind energy there is a Generation payments for every kWh you generate (19.7p/kWh *).  In addition, any Onsite use will avoid normal import at a typical rate of 10p/kWh.  Finally, there is an Export tariff for every kWh you export to the grid (3.1p/kWh *). These are guaranteed and index linked for 20 years from the date your completed turbine is registerd. A number of tariff bands have been defined to encourage generation at different scales, with different payment rates. 500 kW is a sweet spot as the payment rate steps down markedly for turbines larger than this. The Department of Energy and Climate Change (DECC) are responsible for the policy, and the scheme is administered by the Office of the Gas and Electricity Markets (OFGEM).  (* data is for 100-500kW turbines registered in FIT year 2011/2012)

What is the comprehensive review of the FIT?

A comprehensive review of the FIT is currently underway by DECC. This was expected to take place during 2012 and be implemented from April 2013, but was brought forward by a year to ensure that the new government's spending plans can be met. It is underway now and any changes will be implemented from April 2012. It is expected that medium-sized wind will continue to be supported, as Renewable Generation and Localism are key elements of the current government's agenda. It is also expected that there will be minor changes to scheme workings and the level of the tariffs. Until the review is concluded there is some uncertainty regarding the level of payments which will be received by turbines which have been re-rated or de-rated to qualify as 500kW turbines.

What are wind classes?

The design code IEC 61-400 defines four different classes.  These are broadly for: high, medium, low and very low annual mean wind speeds. The classes also define associated criteria such as maximum wind gusts and turbulence intensity. The wind loadings, and energy generated, increase rapidly as annual mean wind speed increases. Turbines are therefore generally designed to be sited up to a particular wind class. Extreme weather events only occur very rarely, but when the next one does, a Windflow turbine will give you confidence as it has been designed and independently certified to the very highest wind class.

IEC wind speed class1234
Annual average wind speed 10 m/s 8.5 m/s 7.5 m/s 6 m/s
Extreme 10 min gust wind speed 50 m/s 42.5 m/s 37.5 m/s 30 m/s
Extreme 50 year gust wind speed 70 m/s 59.5 m 52.5 m 42 m/s
Turbulence intensity A 16%
Turbulence intensity B 14%

How can you assess the wind speed at your site?

The most simple way is to input the post code of your site into a free tool such as NOABL. This however is only a rough indication as it is rather old and only uses kilometer squares. The next approach for accuracy is to pay for a Virtual Met Mast report from the UK Met Office.  This uses analytical modelling to calculate the wind speed at your site based on the closest established wind measurement site. The ultimate approach for accuracy is to install a met mast at your site and take measurements for 12 months.  These readings are then used to correlate your site to the closest established wind measurement site to predict your long term annual mean wind speed.

As Windflow turbines are designed for the highest class of wind speed, we generally require far less information before confirming the turbine's suitability for a site than many other turbine manufacturers. Operating in lower wind speeds than 10 m/s will be a 'breeze' for the Windflow turbines. Please ask for our turbine siting specification if you require more information. We will often be prepared to site our turbines on sites with greater than 10 m/s annual mean wind speed, subject to confirmation.