An Bord Pleanála has opened hearings into two proposed wind farms in Co Mayo.
The ESB and Bord na Móna have applied for permission to develop a wind farm with 112 turbines at Oweninny, while Coillte hopes to build 48 turbines at Cluddaun.
Both wind farms are located close to the former ESB power plant at Bellacorick in north Co Mayo.
The hearings in Ballina will hear from the applicants during the course of the proceedings.
The Owenniny wind farm would involve the construction of turbines with a maximum tip height of 176m.
It would be developed in three phases, with work carried out on different areas of the 50sq.km site.
Work on the first phase would begin in 2015 and be completed by 2017.
The second phase, taking two years, would commence in 2016.
Power generated would transfer to the national grid via the existing substation at Bellacorick.
The hearing has heard that the third phase is dependent on the Grid West development. This stage would involve the construction of turbines that would generate between 190 and 230 kilowatts of wind energy.
Work on this phase would not be completed until around 2022.
Construction would take place beside the existing operational wind farm at Bellacorick.
The State's first commercial wind energy development opened there in 1992 and comprises 21 turbines.
Permission for a larger wind farm on the site was granted in 2003 and has been extended to 2018.
This allows for the construction of 180 turbines but with a smaller maximum tip height.
There are indications it would be implemented in the event of this latest application being refused.