Production of bio-diesel from macro-algae of the Orbetello lagoon by various extraction methods

In the last few years, there has been a significant increase in finding alternative energy sources to fossil fuel. Bio-diesel derived from vegetable oils has been shown to be a potential alternative. Presently, most of the available bio-diesel is made from edible oils, but it is believed that with a large-scale production of bio-diesel these stocks may cause an imbalance to the food supply. Algae and aquatic bio-mass have the potential to provide a new range of third generation bio-fuels. Recently, there has been substantial increase in attention to the possibility of using aquatic bio-mass. The aim of this study was to evaluate the macro-algae oil yield and lipid composition in order to produce bio-diesel from waste bio-mass. The algal bio-mass comes from the Orbetello lagoon (Southern Tuscany, Italy), where macro-algae grow naturally due to eutrophication and are harvested and stored in a landfill as a special waste product. Lipid extraction was carried out according to the Bligh and Dyer method and also by using a Dionex ASE200 (accelerated solvent extractor). The total lipid content was determined by micro-gravimetry and the fatty acids (FAs) by GC-FID and GC-MS after acid transesterification. Chaetomorpha linum was the most abundant species and had the highest lipid content. Lipid concentrations and profiles of the Orbetello lagoon's macro-algae were comparable with those reported in the literature for the same species or genus. Algal FAs corresponded to those that normally constitute bio-diesel. Thus, the results indicate that bio-diesel could be produced from the harvested algal bio-mass.