The companies plan to use the €80m project as a key first step for the development of a larger 870MW wind farm in the Irish Sea, dubbed the North Irish Sea Array (NISA).
Gaelectric and Oriel have urged the Irish Government to extend a feed-in tariff for wave and tidal energy to include offshore wind demos up to 30MW.
The NISA demonstration project will allow international firms use the Irish Sea as a testing ground for new innovations in offshore wind energy technology such as turbines, cables, and foundations.
Oriel Windfarm managing director Brian Britton said: "This project represents the biggest step forward for the Irish offshore wind energy sector in the last ten years.
"NISA will commence with a significant demonstration project which, by their nature, draw investment and attract collaborations with local universities and provide opportunities for local businesses."
Gaelectric CEO Brendan McGrath said: "We are confident that the project will attract leading industry players to the offshore Irish market and will be an important step towards realising the vast potential for renewable generation from the Irish Sea."
The Irish government believes there is a potential to generate up to 10,000MW of renewable energy from offshore wind energy.
