In addition to the current uses of algae as food and as sources of pigments and polysaccharides, there is potential for the further use of algae as sources of additional specific biomolecules. In addition to this, there is the possibility of the use of alga in a wide variety of processes such as bioenergy (production of liquid fuels and algal biophotovoltaic generation of electricity), removing pollutants from wastewater, and the production of plant growth enhancers and crop protection materials. The eventual commercialisation of these requires the processes to be scalable and economical. The targeted use of algae, other than as food sources, is less than 100 years old and our knowledge of algal biology, physiology and chemistry is still growing and only a very small number of algal species have been studied in detail. One of the main limitations is the need for more reliable, lower cost and larger-scale algae production systems and their development, in turn, requires a good understanding of basic algal biology and life histories. In addition, more work is needed on increasing the efficiency of light utilisation in photosynthesis and hence in growth.