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Oweninny Wind Farm (Phase 1)

The Oweninny Wind Farm is the largest wind farm to be completed in 2019 in Ireland. In May 2017, Oweninny Power DAC, a 50:50 joint venture project between Electricity Supply Board (ESB) and Bord na Móna, awarded a contract to Roadbridge with Sweco as Designer to design and build the 2- turbine wind farm in northwest Mayo. Having worked on over 200 wind farms across Ireland and the UK, the Sweco team brought an enormous depth of knowledge to the project.

Facts & Figures

May 2018 – September 2019
Primary services
See details below

Project Overview

The Oweninny Wind Farm project is a prime example of the successful transition from brown to green energy production. The site for the wind farm was formerly used for peat harvesting to provide locally sourced fuel for ESB’s peat fired power station at Bellacorick, up to its decommissioning in 2003. The country’s first commercial wind farm was established at the site in 1992 with 21 turbines. The older turbines were decommissioned and have now been replaced by 29 turbines producing 89MW of clean energy. This continues the long association of the site with power generation which is now 100% renewable.

The design, led by Sweco’s team in Cork, was completed in September 2019 allowing for the timely delivery and installation of turbine components.



  • Design of 29 turbine bases in varying ground conditions to the specific requirements of the Siemens Gamesa 3.2MW turbine
  • Geometric design of 24km of internal road in challenging ground conditions
  • Design of crane hard standings and blade laydown areas for each turbine
  • Sustainable drainage design for access roads, turbine bases and hard standings
  • Design of environmental mitigation
  • Advice on surface water management in accordance with Oweninny Boglands Rehabilitation Plan
  • Full time site supervision of turbine base construction


Key Facts

  1. Following instruction by the ESB-BnM at the end of May 2018 to proceed with construction of the turbine foundations, the combined team delivered the construction and handover to Siemens of all 29 bases (some 15,000m3 of reinforced concrete) at the end of March 2019.
  2. Sweco reviewed the initial site design and eliminated the need for 7 turbine bases to be piled, by designing partially submerged gravity bases which would be flood resilient and water compatible minimising the impact from natural wetland water flows.
  3. The wind farm will provide energy for approximately 50,000 households and an annual reduction of 100,000 tonnes of carbon dioxide, a significant contribution to meeting the targets set out in Ireland’s Climate Action Plan.