This report has been commissioned by Sustainable Energy Ireland in order to provide an overview of marine algae as an energy resource, from either macroalgae or microalgae. It is also required to assess the potential resource in Ireland, determine the level of activity and identify research and development knowledge gaps. A supply-chain analysis was carried out for both macroalgae and microalgae, technologies identified and research topics proposed to evaluate commercialisation potential of these resources for energy. For the purposes of this report tentative roadmaps based on high, medium and low scenarios are hypothesised for development of these resources by 2020.