Bio-gasification of post transesterified microalgae residues: A route to improving overall process renewabilities

Using results from experiments and process modelling tools, a renewability assessment was carried out for the use of the conventional and in-situ transesterification processes for a large scale microalgae biodiesel production. In a present day scenario, all the transesterification processes were shown to be non-renewable. The process renewability of biodiesel production from microalgae was found to significantly improve with the use of renewable electricity, reacting alcohols from biomass fermentation and process heating and biomass drying using heat from wood pellet combustion or heat pump technology. The anaerobic digestion of the microalgae residues to generate methane from was further seen to lead to positive renewabilities for the considered microalgae-biodiesel processes.