SSE has suffered a major setback to its plans to dev- elop a new oil-fired power generation plant outside Duleek, Co Meath.
The renewable energy firm's project was refused planning permission because of its impact on greenhouse gas emissions.
An Bord Pleanala has upheld an appeal by local residents against the decision of Meath County Council to approve the construction of a 208MW open cycle gas turbine "peaker" power plant at Platin, Co Meath.
The board voted by a five to three majority to refuse planning permission for the facility, which was designed to act as a back-up power plant at periods of high electricity demand.
Although the board found the site suitable for electricity generation, it said a plant operating on natural gas or other fuel source - which did not require the use of distillate oil - was warranted.
An inspector with An Bord Pleanala described SSE's choice of fuel for the plant as "misplaced" and observed that to approve such a project would be "irresponsible".
SSE said the project was designed to ensure the security of electricity supply in the north-east region.
The company said it had sought to develop the facility on its own greenfield site in an area where industrial use was allowed.
The proposed development had consisted of two separate components - the peaker power plant and a new 110kV transmission substation, which would have connected the new plant to the national grid.
SSE said it would have provided support to the national electricity system during peak times by prov- iding electricity back-up.
However, the An Bord Pleanala inspector said: "One cannot support the relocation and re-use of infrastructure and choice of fuel that maintains and continues to promote an unacceptable level of greenhouse gas emissions."