Ireland set out to produce 33% of its electricity demand from renewable sources by 2020 and reduce emissions to the level of 1990 in accordance with the Kyoto agreement. These targets require investments in a diverse range of power sources. This paper investigates if Tidal Stream Generators (TSG) can become an economically viable system. Initially a levelised cost was established for tidal and other energies at a baseline year of 2010. Due to the early stage of development of tidal energy, it is difficult to accurately predict its future capital investment and operational cost. For this reason future costs were estimated for all energy forms and a present worth was established. From this a levelised cost over the project lifetime was calculated. At this point it was found that Tidal Energy was a competitive form of energy. The feasibility of tidal energy was assessed using both constant and varying Renewable Feed In Tariffs (REFIT). Using 2010 values a profit of €1.671Billion could be achieved with a maximum investment of €135million. However if REFIT changed to 32€/MWh after the contractual 15 years, a profit of around €200million can be achieved with a maximum investment of around €213million.