Preliminary investigation on the production of fuels and bio-char from Chlamydomonas reinhardtii biomass residue after bio-hydrogen production

The aim of this work was to investigate the potential conversion of Chlamydomonas reinhardtii biomass harvested after hydrogen production. The spent algal biomass was converted into nitrogen-rich bio-char, biodiesel and pyrolysis oil (bio-oil). The yield of lipids (algal oil), obtained by solvent extraction, was 15 ± 2% w/wdry-biomass. This oil was converted into biodiesel with a 8.7 ± 1% w/wdry-biomass yield. The extraction residue was pyrolysed in a fixed bed reactor at 350 °C obtaining bio-char as the principal fraction (44 ± 1% w/wdry-biomass) and 28 ± 2% w/wdry-biomass of bio-oil. Pyrolysis fractions were characterized by elemental analysis, while the chemical composition of bio-oil was fully characterized by GC–MS, using various derivatization techniques. Energy outputs resulting from this approach were distributed in hydrogen (40%), biodiesel (12%) and pyrolysis fractions (48%), whereas bio-char was the largest fraction in terms of mass.