Effects of temperature and holding time on production of renewable fuels from pyrolysis of Chlorella protothecoides

To investigate the influence of temperature and holding time on the pyrolyzate yields of Chlorella protothecoides, the microalgal cells were subjected to pyrolysis at 200, 300, 400, 500 and 600 degrees C for 5, 20, 60 and 120 min, separately. High oil yields above 40% dry weight cells were obtained both at relatively low temperature (300 degrees C) with relatively long holding times (20-120 min) and relatively high temperatures (400-500 degrees C) with relatively short holding times (5-20 min). The maximum oil yield of 52.0% was achieved at 500 degrees C for 5 min. The gas yield was generally increased with the increasing temperature and holding time. It could reach 63.3-76.0% at 600 degrees C. High pyrolytic rates of 72-87% were obtained at all experiments except at 200 degrees C for 5-20 min or 300 degrees C for 5 min. Thermogravimetric analysis indicated that the main thermal degradation of this microalga occurred at 200-520 degrees C. The results imply that C. protothecoides is a good candidate for the production of renewable fuels by pyrolysis.