The Algae Cluster is a group of three European Commission funded projects, each building a different demonstration algae biofuel facility up to 10 hectares in size. Each project is carrying out an independent Life Cycle Assessment (LCA) to understand the various environmental impacts of the biofuel production. A major issue with LCA is that there is a high flexibility on defining metrics such as the boundary conditions, functional unit and impact categories. The LCA practitioners for these three projects have agreed upon a harmonised approach, with the intention of ensuring the projects are comparable. This paper details the logic behind this approach, and shares it with the community. The purpose of this paper is to introduce the three algae demonstration projects and to present a harmonized methodology for LCA of algae biofuels. With this, work by different researchers may be compared more effectively, making it easier to measure the effectiveness of different strategies in algal biofuels with regard to sustainability. (C) 2015 Elsevier Ltd. All rights reserved.