CO₂ process intensification of algae oil extraction to biodiesel

Abstract

Algae‐to‐biodiesel processes are hindered by high costs and low energy return on investment.1,2. Herein, three foci in research improve algae‐to‐biodiesel processes by: (1) reducing high installation and energy costs in the CO2 sequestration, cultivation, and harvesting stages; (2) improving oil extraction and biodiesel generation; and (3) increasing utilization of the proteins in lipid‐extracted biomass (e.g., for animal feed), as well as the omega‐3 fatty acids for nutraceuticals and food supplements. A process is introduced that uses carbon dioxide to aid in all three of these foci. CO2 is used first in the form of microbubbles to lyse algae cell walls, releasing triglyceride oils. CO2 also aids with transesterification of these triglycerides using methanol. At low temperatures (353.15–368.15 K) and intermediate pressures (5–10 MMPa), carbon dioxide causes methanol to dissolve partially in the triglyceride phase and triglyceride to dissolve partially in the methanol phase, increasing the transesterification reaction rate. Due to the nondestructive nature of these processes, other metabolites can also be harvested providing improvements in both mass and economic efficiency with an overall sharp reduction in the modeled price of biodiesel.

Systems level roadmap for solvent recovery and reuse in industries

“…This intensification was done by premixing the algae extract stream with methanol solvent before sending the material in for transesterification. Supercritical CO 2 was added ( Yadav et al., 2021 ). The temporal domain modifies the timescale of the process to create the possibility of obtaining the product at a smaller timescale.…”

Current Status and Future Trends in Removal, Control, and Mitigation of Algae Food Safety Risks for Human Consumption

“…Meanwhile, microalgae are also known as the third generation of bioethanol different from traditional energy sources. Furthermore, biodiesel has been produced from the extraction of lipid-rich algae, such as Chlorella , Selenoses , and Dinoflagellates , over the past decade and methods of extraction have also been improved [ 7 , 8 , 9 , 10 ]. In addition to the development of new liquid fuels, research on solid fuels is not standing still.…”