They are becoming an increasingly common sight around Ireland, and over the coming decades, wind farms will be commonplace off our coasts. However, wind farms are complicated projects with a lot more going on than meets the eye.

To find out what’s involved in developing and running a wind farm, the Irish Farmers Journal recently visited the completed Lenalea wind farm project in Donegal.

The wind farm is a 50-50 joint venture onshore wind project between SSE Renewables and FuturEnergy Ireland.

FuturEnergy Ireland is a joint venture between the ESB and Coillte. Ghislain Demeuldre, head of onshore development, Ireland, SSE Renewables, explained that the partnership intents to develop seven projects across multiple sites, all on or partially located on Coillte land. Lenalea wind farm is the most advanced project in the portfolio.

When we visited the wind farm on a rainy day in November, the first thing that struck me was the attention to health and safety.

We met the team at the wind farm office and workshop outside Letterkenny.

There are a lot of health and safety protocols when entering the site. Each turbine is producing millions of kilowatts of electricity, which runs through live underground cables from each turbine to the substation.

After receiving a comprehensive health and safety briefing from Noel Herron, SSE Renewables, and equipping ourselves with the necessary personal protective equipment (PPE), we proceeded towards the wind farm.

The turbine tower comes in three parts and are bolted together as they are erected.

Donegal man Pat Greene, project manager for the site, talked us through the project. Lenalea wind farm is located in the rural upland setting of central Donegal, around 8km southwest of Letterkenny.

The project secured planning permission in January 2010 but was unable to progress due to the lack of access to the electricity grid.

Lenalea wind farm consists of seven turbines, each with a tip height of 136m.

The blades are 57m long, and the hub height of each turbine is 76m. The wind farm has an installed capacity of 30MW and will generate enough renewable energy to power 20,000 Irish homes annually and offset 20,000 metric tonnes of carbon per annum.

Some of the members of the team who we spoke to on the day. From left: Fergal McCarron, Vestas; Ghislain Demeuldre, SSE Renewables; Nicola Murphy, SSE Renewables; Patrick Greene, Lenalea project manager and Emmet McLaughlin, FuturEnergy Ireland.

The project was successful in the Renewable Electricity Support Scheme (RESS1), meaning it will receive guaranteed revenue for the electricity it generates for a 15-year period.

Five of the seven bases use gravity bases, with a diameter of 20m, have a depth of two meters, use 70 tonnes of steel reinforcement, and use 450m² of concrete.

SSE Renewables owns and operates a number of wind farm sites adjacent to Lenalea, collectively known as Meentycat, with a total generation capacity of 88.5MW.

How wind works

Fergal McCartan, the Lenalea site manager at Vestas, described how turbines function by capturing wind energy and converting it into rotational energy.

This process begins when the wind strikes the turbine blades, causing them to rotate. This rotation moves a rotor, which then passes through a gearbox.

The wind turbine blades being delivered to the site, passing the Dry Arch roundabout in Letterkenny.

The motion in the gearbox ultimately drives a generator, transforming the rotational energy into electrical energy.

The size of the turbine blades directly affects the amount of energy they can capture: larger blades cover a larger swept area, thus capturing more energy.

At the Lenalea site, each wind turbine has a substantial swept area of 10,751 square metres.

The Lenalea Wind Farm initially received planning permission in 2010.

The turbine components are bolted together.

Once the energy is generated, it is converted into high-voltage electricity. This high-voltage electricity is then transported to a substation, from where it is exported onto the electricity grid.

Wind turbines

In March 2021, the partnership announced that Vestas would supply and install seven V117-4.3 MW wind turbines. Fergal explained that Vestas, the global turbine manufacturer, has a significant presence in Ireland with 116 employees. A Letterkenny-based team looks after the Lenalea turbines.

A new substation was built on site to connect to a 110KV powerline.

The wind turbines at Lenalea come in three separate tower sections, which get bolted together during installation.

The box at the top of the turbine is called the nacelle, which houses the drive train, including the gearbox and generator, as well as the transformer.

Vestas has a team of 116 people working in Ireland.

These modern turbines are equipped with smart technology, including the ability to automatically adjust the pitch of their blades to control the airflow through them.

The substation will likely see another wind farm connect to it in the coming years which is about to go into the planning system.

This feature allows the turbines to be deactivated and safeguarded during periods of excessive high winds or storms.

A fibre optic cable also runs from the turbines, which provides a means of controlling the turbines. When there is an excess of power generation on the grid, the network operator, Eirgrid, can remotely deactivate wind farms.

The turbine components making their way to the site.

The wind farm has an installed capacity of 30MW.

Moreover, the entire nacelle containing the blades, motor, radiator, and more, can be rotated to optimise the wind capture which is at the highest when the rotor is positioned 90 degrees into the wind direction. This is automated through a wind station located atop the turbine.

At the Lenalea site, each wind turbine has a substantial swept area of 10,751 square metres.

The turbine is built to handle strain and as I watched the 57m wind turbine blades turn, you can see the tips curve, a specific structural design to cope with wind-induced stress.

Capacity factor

Ghislain explained that the capacity factor of the Lenalea wind farm was around 34%. The capacity factor of a wind farm site essentially describes its windiness and the efficiency of converting that wind into energy.

Turbine construction

Pat explained that a new 6km road was built through the site to service the wind farm, using stone quarried from the site. The infrastructure is built on the site first, before erecting the turbines. This includes the roads, cables and bases.

The Nacelle being delivered to the site.

Depending on the bearing capacity of the ground, the turbine bases are either made with concrete and reinforcement steel or a combination of concrete and concrete piles.

Five of the seven bases use gravity bases, with a diameter of 20m, a depth of two metres, use 70 tonnes of steel reinforcement, and use 450m² of concrete.

The other two use piles to support the turbine foundations, consisting of 18 piles of 900mm diameter, 18m to 9m deep.

Once the bases are complete, they run all the cabling between the bases to the substation. The turbines are erected using a 96m hook height crane on a purpose-built hardstand.

Part of the new substation.

Pat explains that erecting the wind turbine can be tricky, as turbine installation work on the Lenalea site had to stop when wind speeds went over 9m/s. This is challenging considering wind farms are built on windy sites with wind speeds frequently in excess of this.

With stoppages, they allow one week per wind turbine to erect.

Turbine route

Pat explained that a huge amount of work goes into planning the route for the turbine blades and components from the port or source of import to the site, known as the turbine delivery route (TDR).

For Lenalea, the blades came from Killybegs port, which went to Lifford, then to Letterkenny, and finally into Lenalea. It included mapping the roads, carrying out swept path analysis and working with land landowners for land access, particularly in tight corners or sharp bends.

Some of the project team members explaining the key components of a wind turbine.


The grid infrastructure in the area is critical to the whole development. Developers are looking to be near an electricity node for a connection. The project had to build a new substation, which connects directly to the 110kV powerline running though the site.


Like any well-oiled machine, maintenance is important, and wind turbines are no different.

Vestas maintains the turbines and services can vary from changing grease on bearings to changing oil in the gearbox, to checking the bolts that bolt the turbine together for integrity.

The turbines have a built-in network of sensors, which checks temperatures, oil levels, stress on the blades 24/7.

Turbines will last for 30 to 35 years when well maintained, and this can be extended.

Site selection

Developing a wind farm is a long process, averaging between seven and 10 years from identifying a site to beginning to generate energy.

Selecting a site is complex, and not all of the country is suitable for wind farm development.

Collaboration between developers, landowners and farmers is geared toward enhancing biodiversity on the site

Emmet McLaughlin, FuturEnergy Ireland, explains that it all begins at the desk with a desktop assessment. Using GIS mapping, sites are screened for their location and proximity to designated or environmentally protected sites, as well as proximity to grid, topography, wind speeds and any peat depths.

Pat explained that a new 6km road was built through the site to service the wind farm, using stone quarried from the site.

They then take it from the national level to the local level and look at the local development plan, considering the zoning of the land and the characteristics of the site, such as soil type, topography, nearby watercourses, peat, opportunities for borrow pits for rock, and much more.

Once the site is selected, the planning application process is rigorous, explains Ghislain.

He says it takes, on average, around three years from the site being identified to an application being submitted, due to the volume of reports and studies needed. There are dozens of chapters in an environmental report looking at everything from water to geotechnology, noise, traffic and much more.


Private landowners usually enter into a 30- to 35-year lease agreement with wind farm developers for the site.

Emmet elaborated that farmers along the route may also be approached for co-operation, especially when it comes to expanding corners or laying grid connection cables, as specific land agreements are in place for such scenarios.

Collaboration between developers, landowners and farmers is geared toward enhancing biodiversity on the site with the goal of achieving a net increase in biodiversity, explains Pat.