Bogland used by Bord na Mona in the Midlands has been converted into a 115 million euro wind farm with enough power to generate electricity for 45,000 homes.
The Mountlucas energy project near Daingean in the east of Offaly - the first built on a cutaway bog - has been switched on to supply up to 84 megawatts of power to the grid.
It is one of a series of wind farms the energy company is planning to build, mostly on former bogland, over the next seven years.
Under the renewable project, 28 turbines were erected on the 1,100-hectare site and it was part-financed under the target to get 40% of Ireland's electricity generated from renewable sources by 2020.
The MIdlands windfarm projects are not without massive community opposition, with many proposed schemes dogged by legal disputes and grassroots campaigns against them.
Bord na Mona said Mountlucas was the largest single investment in its history and 12 people will be employed during its operation..
Managing director Mike Quinn said: "This windfarm is part of our answer to Ireland's twin energy challenge.
"It is becoming ever more apparent that we must reduce our chronic dependence on gas and oil supplies from unreliable sources.
"Even more critically, we have a pressing obligation to de-carbonise our energy supplies to radically reduce greenhouse gas emissions and help Ireland avoid significant missed-target penalties."
Opponents of the development from the Wind Aware Ireland group have hit out at the proximity of the 150-metre (490ft) high turbines to isolated homes on the edge of the bogland and also claimed the concerns of local people were ignored during planning and development.
Bord na Mona is overseeing a bog rehabilitation programme as part of Mountlucas, including a 5km (three-mile) amenity trail for walkers across the bog.