We examine the economic and environmental impact that the installation of 3GW of marine energy capacity would have on Scotland. This is not a forecast, but a projection of the likely effects of meeting the Scottish Government’s targets for renewable energy through the development of a marine energy sector. Energy, with a particular focus on renewables, is seen by the Scottish Government as a ‘‘key sector’’, with high growth potential and the capacity to boost productivity (Scottish Government, 2007a. The Government Economic Strategy. The Scottish Government, Edinburgh). The key nature of this sector has been identified through targets being set for renewable energy to achieve environmental and economic benefits. Using a regional computable general equilibrium (CGE) model of Scotland we show that the development of a marine energy sector can have substantial and beneficial impacts on GDP, employment and the environment over the lifetime of the devices, given the encouragement of strong indigenous inter-industry linkages. Furthermore, there are also substantial ‘‘legacy’’ effects that persist well beyond the design life of the devices.