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Figure 0.28 Concept for offshore open ocean farming179 The available surface for this type of cultivation is enormous (more than 25 million km2). The seaweed produces polysaccharides that could be converted to ethanol, Butanol or methane. Sargassum natans also contains interesting amounts of proteins that could be used as feed for animals. ECN suggests that the potential of this resource may be large enough to replace all oil and soy production in the world. On a global scale there is significant microalgae research. Most research on microalgae for energy production is aiming at the production of lipids. A microalgae produces lipids as a reaction to a shortage of food. As shown in Table 0.19, Isochrysis galbana, Tetraselmis sp. and Phaeodactylum tricornutum have high proportions of lipids. Table 0.19 Algal strains suitable for Marine cultivation Marine strain Isochrysis galbana Tetraselmis sp. Synechococcus sp. Chlorococcum littorale Chlamydomonas sp. Nannochloropsis salina Phaeodactylum tricornutum Dunaliela tertiolecta Chaetoceros muelleri Botryococcus braunii Emiliania huxleyi Some researchers in Europe and the US are working on a different approach for the biofuel production with microalgae. They use microalgae to directly produce ethanol. So not the hard to harvest microalgae need to be collected but only the ethanol need to be recovered from the process water. The microalgae stay alive and are used as living ethanol producers. The European research project DEMA is working on this181. 179 Ursem, Herfst, TU-Delft, 2008 180 See: http://www.whoi.edu/cms/files/Goepfert_Defense_60363.pdf 181 See: http://cordis.europa.eu/fetch?CALLER=EN_NEWS&ACTION=D&SESSION=&RCN=36026 Lipid%180 25-33 % 15-23% Stage Biofuel Biofuel Ethanol Hydrogen Biofuel 20-30% 23% Research Research Research Research Research 142 Study in support of Impact Assessment work on Blue Biotechnology

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