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Frequently Asked Questions

On this page you will find frequently asked questions about wind energy. If you don’t find the answer you’re looking for please contact us and we will be happy to help.

What is renewable energy?

Renewable energy is generated from natural resources such as wind, sun (solar energy), water (tidal energy), wood, waste and energy crops (biomass). These natural resources are considered to have a never-ending supply as they are continuously replenished through the cycle of nature – unlike fossil fuels which will eventually run out. Renewable energy can also be referred to as clean energy or sustainable energy.

What is wind energy?

Wind energy is a source of renewable energy. It is naturally occurring. As the sun heats the earth, the hot air rises up and cool air replaces it in order to achieve a balanced temperature – this results in wind. As the wind sweeps across the land, it creates kinetic energy. We can capture this energy with wind turbines and transform it into electricity.

What is a wind turbine and how does it work?

A wind turbine is a machine that transforms the kinetic energy of the wind into mechanical or electrical energy. There are four main components to a wind turbine: the foundation, tower, nacelle and rotor. Inside the nacelle is the main axle, generator, transformer, gearbox and control system. While the rotor consists of the blades and the hub. Wind turbines generally have 3 blades.

As the wind blows, it sets the rotor blades in motion. The generator transforms the energy of the motion into conventional electrical energy.  From there, the electricity flows through power lines to hospitals, schools, homes and businesses.

Do all wind turbines have gearboxes?

No. Some wind turbines use a direct drive mechanism to produce power from the generator instead of a turbine.

Why do some wind turbines spin, while others next to them do not?

A wind turbine may not spin for three main reasons:

  • The wind turbine may be undergoing maintenance work for this reason they have to be stopped.
  • If the wind is too strong, the turbine will have to be shut down to avoid any damage occurring.
  • The speed, direction and force of the wind are constantly changing – even within a small area. If the wind speed and force is low and the wind blowing in the wrong direction it will not be strong enough to spin the turbine.

How strong does the wind have to blow for the wind turbines to work?

The wind turbine will start operating at wind speeds of four to five metres per second. At speeds of 15 metres per second, the wind turbine will reach its maximum output. If the wind speeds reach 25 metres per second or greater, the turbine will be shut down to avoid damage to the turbine occurring.

What is a wind turbine made of?

The towers are mostly tubular and made of steel. Some towers may be made of concrete. The blades of the turbine are made of fibreglass, reinforced polyester or wood – epoxy. Generally, wind turbines are painted a light grey.

What size are wind turbines?

The turbines on Bord na Móna’s Mountlucas and Bruckana Wind Farms are 100m in height, with a rotor diameter of 100m. From the base of the turbine to the tip height it is 150m or 492 foot.
The average capacity of a wind turbine is 2.5 – 3.0 MW. This is enough to power 1,500 average EU homes. The largest turbines available are currently 7.5 MW.

What is the lifespan of a wind turbine?

Wind turbines have an estimated life span of 20 – 25 years. They are designed to work for 120,000 hours over the two decades. Wind farms can surpass the 20-year life span. Bord na Móna’s wind farm in Bellacorick was commissioned in 1992 and is still operational.

What happens a wind farm when it is decommissioned?

Decommissioning a wind farm is simple and straightforward. When a wind farm is decommissioned the turbines can be removed and the land/site restored to its original state or as close as practicable. The decommissioning of a wind farm should be covered by clauses set out in the planning permission. Depending on the size of the wind farm and the geography of the development it is assessed on a case by case basis.

What is shadow flicker?

Shadow flicker’ occurs where the blades of a wind turbine cast a shadow over a window in a nearby house and the rotation of the blades causes the shadow to flick on and off. This effect lasts only for a short period and happens only in certain specific combined circumstances such as when:

  • The sun is shining and is at a low angle (after dawn and before sunset); and
  • The turbine is directly between the sun and the affected property; and
  • There is enough wind energy to ensure that the turbine blades are moving.

Irish wind farm sites are generally not likely to encounter significant shadow flicker. For those sites that are affected, the potential for flicker can be calculated prior to construction and turbines can be sited to minimize impacts on residences. Where shadow flicker is anticipated to lead to potential problems, measures can be implemented to mitigate these effects. Wind turbine control software is available, which can turn the relevant turbine off at these times.

What is shadow casting?

Wind turbines, like other tall structures, will cast a shadow on the neighbouring area when the sun is visible. Fortunately, it is possible to predict quite accurately the probability of when and for how long there may be shadow casting. A bit of careful planning, and the use of good software to plan a wind turbine site can help to resolve this problem by locating the turbines to avoid any major inconvenience for neighbours.

Can the wind farm land be used for other purposes?

Yes, the wind turbines occupy a comparatively small footprint. Therefore, it is possible, depending on site-specific issues, to accommodate complementary uses of the land –ranging from farming activities, local recreational activities, to tourism facilities

How much electricity does one wind turbine generate?

There are a number of factors involved in determining how much electricity one wind turbine generates. These include the turbine’s size and the wind’s speed. Based on the average wind turbine of 2.5 – 3 MW per hour, it can produce over 6 million kWh in a year – equivalent to enough energy to supply 1,500 average EU homes.

Are wind turbines noisy?

Wind turbines can generate two types of noise: mechanical noise from the gearbox and generator in the nacelle, and aerodynamic noise from the blades. Turbine design has evolved to minimise both of these, through improved soundproofing of the nacelle, and through streamlining and refinement of the turbine blades. It is commonly agreed by unbiased commentators that the turbines pose a minimal audible intrusion to the environment.

If you cannot find the answer to your question, please contact us and we will be happy to answer any query you may have.