Irish Wind Energy Association

Can wind farms be built on forested land?

How do higher trees affect wind turbines?

Higher trees affect wind turbines in two ways:
1. reduction of overall energy production for the turbine / windfarm, and
2. the generation of turbulence which can cause vibrations through the blades leading to greater stress on the turbine drive trains.

Is there a required radius of forest clear-fell around turbines for wind-turbulence reasons? Is this radius being driven by Warranty and Maintenance conditions from turbine manufacturers?

The answer to this question depends on the manufacturer. It is definitely better to have no vegetation as this results in less ‘drag’ on the wind and therefore more energy production.

However different manufacturers have different requirements. The issues are the height of the trees and the distance between the trees and the turbines. There is no standard clearance area, although 500m back from most turbines is considered ample. The allowable growth height of the trees will depend on the height of the turbine and the length of the blades. The rate at which the trees grow also has to be taken into consideration.

Is it required to obtain a tree-felling licence?

According to the 1946 Forestry Act, a felling licence is required to fell any trees more than 10 years old. This means that it is unlawful to fell trees older than 10 years without a statutory licence – there are some minor exceptions to this rule, but it applies to all commercial forest plantations.

On all commercially forested lands (both state-owned and private), is the replanting of a felled area required; or are substitute planting lands required to replace the lost forest area?

Generally, all trees that are felled must be replanted with new trees. Where space has to be cleared for access roads and turbine bases, it is necessary to plant trees on alternate land of an equivalent area. There are other requirements contained in a specific policy on tree felling for windfarms issued by the Forest Service in 2009:
Felling Policy For Wind Farms

If the forested land has been grant funded, is it necessary to repay the grants if the trees are cleared?

For any forests that were grant funded, all money, grants and premiums must be repaid where the trees are cleared prematurely – it is best to consult with the Forest Service on an individual basis
http://www.agriculture.gov.ie/forestservice/

Can the replanting of 'clear-fell' areas around the turbines, be satisfied using slow-growing species like North Coast Lodgepole Pine?

The type of tree to be used for replanting must be agreed with the Forestry Service and might depend on what the land can support in terms of nutrients. According to clause 7 of their current policy on tree felling and windfarms (Felling Policy For Wind Farms) it may be possible to plant short rotation forestry on windfarm sites. This effectively means that you can plant a species (to be agreed with the Forestry Service) for a shorter crop rotation than is normal (Normal forest rotation is in the region of 40 years). The effect is to limit the top height of the trees to that specified by the supplying turbine manufacturer. The resulting crop could be chipped and sold for biomass. Importantly, the forestry land will need to be replanted after each felling event.

How do I go about obtaining a licence?

Application forms for tree felling licences and contact details for enquiries can be obtained on the Forestry Website.