There are thousands of different algae species which vary with respect to the structure and composition [2], [3] and [4]. They can be roughly grouped into three categories: green, brown and red algae. In terms of structure, algae are similar to land plants and consist of stiff and strong cellulose-based fibrils which are embedded in a soft amorphous “matrix”. Contrary to plant fibres, cellulose content is less than 10 wt% of the dry mass of algae and the chemical composition of the “matrix” as well as the ratios between the constituents greatly vary within the species.