Comparison of pyrolysis and hydrothermal liquefaction of Chlamyclomonas reinharcltii. Growth studies on the recovered hydrothermal aqueous phase

The production of bio-oil by pyrolysis with a high heating rate (500 K s(-1)) and hydrothermal liquefaction (HTL) of Chlamydomonas reinhardtii was compared. HTL led to bio-oil yield decreasing from 67% mass fraction at 220 degrees C to 59% mass fraction at 310 degrees C whereas the bio-oil yield increased from 53% mass fraction at 400 degrees C to 60% mass fraction at 550 degrees C for pyrolysis. Energy ratios (energy produced in the form of bio-oil divided by the energy content of the initial microalgae) between 66% at 220 degrees C and 90% at 310 degrees C in HTL were obtained whereas it was in the range 73-83% at 400-550 degrees C for pyrolysis. The Higher Heating Value of the HTL bio-oil was increasing with the temperature while it was constant for pyrolysis. Microalgae cultivation in aqueous phase produced by HTL was also investigated and showed promising results. (C) 2014 Elsevier Ltd. All rights reserved.