Bioethanol production from carbohydrate-rich biomass of marine microalgae
Conference contribution, 2011
The world-wide demand for renewable energy sources has put focus on the use of biomass as raw material for fuel production. Up to date plant materials has been used to produce ethanol and biodiesel from carbohydrates and lipids, respectively. However, microalgal biomass has also potential to provide these compounds for production of fuels. In this research project we want to use algal biomass as a carbohydrate-rich feed stock for bioethanol production by yeast. To obtain efficient hydrolysis, fermentation, and down-stream processes of the ethanol production the carbohydrates in the algal biomass should preferably be present as starch. Some certain groups of algae use starch as storage compound, which can be accumulated in the cells at nutrient limiting conditions. Thus, for a bioethanol production based on algal biomass suitable marine microalgal species that contain starch are needed to be identified. In addition, by optimising culture conditions an algal biomass with optimal cellular composition can be obtained. In our preliminary experiments it was found that some “carbohydrate” algal species could accumulate carbohydrates to a 2-4 times higher level at nitrogen limiting conditions compared to balanced medium. The carbohydrates should then be enzymatically degraded to yield fermentable sugars for the ethanol fermentation. In summary, starch from cultured marine algae might be a good alternative source of sugar to be used as substrate in fermentation.