Speaking to the Irish Independent, Ireland's energy minister, Pat Rabbitte, said he is "doubtful" that the proposals will go ahead.
The Irish and UK governments signed a memorandum of understanding (MoU) last year to export wind power through a subsea link across the Irish Sea to Wales.
This deal now seems to be off the table, with Rabbitte saying that, following a meeting with his UK counterpart, Ed Davey, in Brussels this week, he "can't now see an export project as envisaged".
The agreement would have allowed the Republic of Ireland to build onshore wind farms and deliver the energy back to the UK in a move that was seen as key to helping Britain reach its 2020 targets.
Rabbitte indicated that the tight timescale was a key issue, with a 2020 deadline too ambitious for such a large-scale infrastructure project.
The announcement will come as a blow to developer Mainstream Renewable Power, which had signed an MoU for the development of the transmission line between the two countries. On top of this, the company had planned to erect up to 1,000 turbines in Ireland to provide power to the UK.
Irish utility Bord na Mona also announced last October that it was planning to develop 2 GW of wind farms with a view to exporting power to the UK.
The semi-state-owned company said it would lodge applications for construction consent for the first 1GW by 2015, with a view to bringing the projects online by 2020.
While the UK still has a long way to go to hit its 2020 renewable energy targets, Ireland is much further progressed, with less than 5GW of new capacity needed to hit its quota.