Published Thursday, 15 December 2011
One of the schemes off Rathlin Island and Torr Head will harness tidal power, while the other will use wind power off the south east coast of Co Down.
Together the two schemes could generate up to 800MW of electricity for the local energy market.
The Crown Estate, which manages most of the UK's seabed, is seeking investors and developers to drive the schemes forward.
The Executive hopes the projects will increase renewable energy generation in the region by 40% by 2020.
Energy Minister Arlene Foster said: "The interest to date in Northern Ireland waters is very encouraging and this announcement by The Crown Estate presents the offshore wind and tidal sectors with an excellent opportunity."
"Northern Ireland offers a strong but accessible offshore resource, world class research facilities at our Universities, a strong engineering tradition and an excellent port infrastructure."
Rob Hastings, The Crown Estate's Marine Director said: The energy infrastructure projects to be delivered will not only reap significant economic benefits for Northern Ireland, but will also further diversify the energy supply away from industrial sources to low carbon renewable energy."