Wind Turbines

Fourteen wind turbines each up to 3MW are proposed for the Chelveston airfield site. Each turbine will be mounted on a tapered tubular steel tower supporting the nacelle, hub and rotor assembly including three glass fibre-reinforced polyester blades.

In the design process, 17 turbines were originally considered for the site. However, the scheme was reduced to 14 to ensure that turbines were not sited too close to High Barn Farm and Manor Farm which are close to the south eastern boundary of the site and Yelden.

The installed generation capacity of the wind farm will be
36MW which on an annual average will provide some
9MW. The biomass plant will add a further 4MW at times of low wind power and high electricity demand.

The maximum height from the turbine base to the top of the blade tip will be 125m when the blades reach their highest point. The turbine hub height will be up to 80m with each blade measuring up to 45m. For comparison the existing site mast is 70m tall.

The turbines would start operating when the wind speed reaches approximately 4 metres per second and would reach their maximum rated power output at around 15.0 metres per second.

The turbines are equipped with lightning protection, which protects the entire turbine from the tips of the blades to the foundation. Noise damping is also an integral part of the turbine design to ensure that noise emissions are kept within acceptable levels.

The wind farm will consist of up to 14 turbines and the following associated infrastructure:

• access Roads;
• anemometry mast;
• control building;
• borrow pits (if required), and
• temporary car park and temporary construction compound incorporating laydown area, site office
  and concrete bacthing area.

Typical turbine foundations consist of a 4.8m diameter reinforced central concrete pedestal, together with a reinforced concrete slab of around 15.7 x 15.7m (see diagram below).

The turbine tower will be bolted to the foundation, with each foundation requiring around 350m3 of concrete. To ensure a single block of concrete, it is necessary to pour each foundation in one day.

A temporary “crushed stone” hardstanding area of approximately 18m x 40m (see diagram below) will be required at each turbine base for related construction and crane erection activities.

The estimated on-site construction period for the development will be 9 - 12 months, including reinstatement of temporary working areas. Construction procedures will be carried out in line with Environment Agency guidelines and best practice documents regarding management of pollution risk.

In conjunction with the delivery of exceptional loads such as turbine blades, towers and nacelles, an assessment of the surrounding highways and roads network is being undertaken to determine the most appropriate route for delivery of the equipment.