Although many marine energy technologies are presently being developed, only a small number of devices have generated electricity from the marine environment. From such a small experience base it is difficult to independently assess the economic feasibility of alternative technologies for large-scale electricity generation. With a few notable exceptions, much of the published work on marine energy costing concerns relatively small deployments (up to around 100MW rated capacity) with a strong emphasis on costing the components of individual marine energy conversion devices. A review indicates that there is considerable variation of unit electricity cost estimates even for similar technologies. In part, this can be attributed to different end-user applications and input assumptions. Comparison between individual marine energy technologies is therefore not straightforward, particularly for non-technical groups such as potential investors or policy makers concerned with future electricity generation scenarios.
Informed by consultation with stakeholders and the 22 partners of the EU FP7 EQUIMAR project, we present a summary of alternative approaches used to evaluate the economic viability of a marine energy scheme. For several technology types, the main factors affecting the capital cost, operating cost and revenue associated with a commercial scale marine energy project are identified. To aid identification of high-risk cost areas, indicative quantities are assigned to the uncertainty and scale-dependence associated with several key inputs. This provides a framework for equitable assessment of diverse technologies.