The Irish Government is considering its future targets, policy and programmes for renewable energy for the period beyond 2005. This follows a review in 2003 of policy options that identified a number of different measures to stimulate increased deployment of renewable energy generation capacity. This paper expands this review with an economic analysis of renewable energy price support mechanisms in the Irish electricity generation sector. The focus is on three primary price support mechanisms quota obligations, feed in tariffs and competitive tender schemes. The Green-X computer model is utilised to characterise the RES-E potential and costs in Ireland up until, and including, 2020. The results from this dynamic software tool are used to compare the different support mechanisms in terms of total costs to society and the average premium costs relative to the market price for electricity. The results indicate that in achieving a 20% RES-E proportion of gross electricity consumption by 2020, a tender scheme provides the least costs to society over the period 2006-2020 but only in case there is limited or no strategic bidding. Considering, however, strategic bidding, a feed-in tariff can be the more efficient solution. Between the other two support mechanisms, the total costs to society are highest for feed-in-tariffs (FIT) until 2013, at which point the costs for the quota system begin to rise rapidly and overtake FIT in 2014-2020. The paper also provides a sensitivity analysis of the support mechanism calculations by varying default parameters such as the interim (2010) target, the assumed investment risk levels and the amount of biomass co-firing. This analysis shows that a 2010 target of 15% rather than 13.2% generates lower costs for society over the whole period 2006-2020, but higher costs for the RES-E strategy over the period 2006-2010.