Exergy requirement and efficiency of biological activities of chlamydomonas reinhardtii

Chlamydomonas reinhardtii is considered as a potential lipid producer for industrial biodiesel manufacture. The thermodynamic aspects of the lipid production process is important, since the non-lipid producing biological activities of the algal cultivation consume part of the solar energy captured with photosynthesis, in expense of the exergetic efficiency of the lipid production process. The cultivation of Chlamydomonas reinhardtii is modeled as a three-step chemical mechanism, which represents growth, respiration and lipid production and a thermodynamic analysis is performed. The results have indicated that the cumulative degrees of perfections of the biomass production processes are high when those of lipid production are low, and vice versa. The exergy destruction per unit biomass production are accountable under the favorable biological growth conditions, whereas the highest exergetic efficiency of the lipid production is accountable under the least favorable growth conditions, reconfirming the results of the previous studies that the lipid production takes place under the stress conditions.