Opportunities for switchable solvents for lipid extraction from wet algal biomass: An energy evaluation

Algae are considered an important sustainable feedstock for lipid extraction to produce food ingredients, cosmetics, pharmaceutical products and biofuels. Next to the costs for cultivation, this route is especially hindered by the energy intensity of drying algae prior to extraction and solvent recovery afterwards. Most commonly used lipid extraction methods that can be applied on wet algae biomass were reviewed in this paper. In this work the methods for wet extraction of algae lipids using traditional organic solvents, supercritical CO2 and CO2 switchable solvents are compared with dry extraction on an energy consumption basis. Conceptual process designs have been made to calculate and compare the energy flows. Results show that a significant positive energy balance for lipid extraction is only achieved using a switchable solvent extraction method, making this a very promising method for extracting lipids from algae for use in energy applications.