A new 650 million euro hydro-electric power station is being planned for a disused mine.
Irish and Austrian firms have joined forces in a proposal to turn the old open cast site near Silvermines, Co Tipperary, into a 360-megawatt generation plant - enough to run up to 200,000 homes five hours a day.
The scheme is billed by developers and investors as the most effective generation in Ireland and would involve a wind farm using off-peak power to pump water to an elevated reservoir at night before it is released through turbines during the day to a lower reservoir.
If given planning permission, the Silvermines hydro station will be the second hydro generator in the country, along with the ESB's Turlough Hill, a 292-megawatt facility in Wicklow.
The scheme is a joint venture by European construction and technology companies Strabag Group and Andritz Hydro from Austria and the Irish construction company Roadbridge and developer Siga-Hydro.
The investors claim it will have zero emissions but also help with environmental rehabilitation of the area, with water in the existing reservoir at the disused mine being decontaminated and ultimately ending the seepage of potentially harmful minerals into local water tables.
It has been six years in the initial planning with the next step a detailed feasibility assessment and consultation programme with the local community.
The planning application, which could take 18 months to two years, is to be made later this year and construction would take four years.
About 50 jobs could be created when the plant is up and running.
Environment Minister Alan Kelly described the announcement as a pivotal date for Silvermines and the country.
"It will transform the mining legacy here from an environmentally hazardous to a positive one, as well as trigger very significant and sustainable investment and employment in the local community," he said.
The old mine, 230ft (70m) deep in parts, closed in 1993 and was previously subject to an unsuccessful plan for a super dump.
Project director and Siga-Hydro managing director Darren Quinn said: "This is a once-off opportunity to help remediate and clean up this giant abandoned mining site by creating a new land use, something that will benefit the entire nation. It also provides a link between the mining heritage and a sustainable future for the Silvermines area."
Martin Ullrich, director of Strabag renewable division, said: "The key criteria in selecting the project site were the topographic suitability, short grid connection distance, sufficient water availability, minimum impact on the environment and on cultural heritage and the opportunity that the project presents to offer tangible planning gain."