ASI: Hydrothermal extraction and characterization of bio‐crude oils from wet chlorella sorokiniana and dunaliella tertiolecta

In this research, the potential of geothermal water as an alternative water source was tested for the production of algal bio‐fuels. Two algal species, Chlorella Sorokiniana and Dunaliella Tertiolecta were cultivated in a photo‐bioreactor with tap water and geothermal water. The freshly harvested wet algae samples were used to produce bio‐crude oil samples in a high pressure reactor under a hydrothermal liquefaction (HTL) condition (300°C, 90 bar and solid loading of 9 wt %). Supernatant water obtained after harvesting was used in the HTL experiments. A thermogravimetric analyzer was used to determine the moisture and ash content of the algal biomass. It was observed that the bio‐crude oil yield could be higher than the lipid content in the algae. The GC‐MS analysis of biocrude oils showed the contribution of both lipids and proteins to the yield of biocrude. The highest bio‐crude oil yield of 30 wt % (of dry algae) was obtained with a Dunaliella Tertiolecta sample cultivated in a regular tap water medium. A similar amount of biocrude was achieved with a geothermal water medium. Using a calorie meter, the high heating values of bio‐crude oils were measured and these values ranged from 36 to 38 MJ/kg, which are close to that of crude petroleum oils. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 910–915, 2013