Comparative evaluation of wet and dry processes for recovering hydrocarbon from Botryococcus Braunii

• Drying of B.braunii consumes the half of energy of recovered hydrocarbon.
• Water evaporation on solvent recovery from wet B.braunii is unavoidable.
• Energy profit ratio is negative if solvent in residues is not recovered.
• EPR of wet extraction is about twice that of dry extraction.
• Hydrocarbon can be efficiently extracted from B.braunii without drying.

This study aimed to document the material balance and evaluate the energy profit ratios (EPRs) of two processes for recovering hydrocarbon from the green microalgae Botryococcus braunii, which produces hydrocarbon intercellularly, releases it extracellularly, and accumulates it in the extracellular matrix in colony-form. The first is a wet process that elutes an extraction inhibitor through heat, eliminates it through solid–liquid separation, and extracts a hydrocarbon using hexane. The second is a dry process that extracts hydrocarbon by hexane after drying. The EPR of the wet process (3.5) was approximately twice that of the dry process (1.8). Therefore, hydrocarbon can be efficiently recovered from B. braunii without drying.