A One-Pot Approach to Algae Biodiesel
There might be little need for a multi-step algae-to-biodiesel method as long as Lindsay Soh of Yale University continues her research. Soh is creating a process that involves supercritical carbon dioxide (CO2) to extract the lipids from algae and through her work at the Zimmerman lab, led by Julie Zimmerman, associate professor of green engineering, Soh has also created what she refers to as one-pot biodiesel. The idea, as Soh explains it, combines the process of supercritical CO2 lipid extraction with the use of a solid catalyst, all in the same reactor. “You can actually put algae in your vessel and you will be getting biodiesel out,” she says, all of which will improve the efficiency of the process and cut down on the number of steps.
According to Soh, CO2 is a great solvent that is ideal for lipid extraction, and it is more environmentally friendly than chlorinated or industrial solvents. The use of CO2 also allows for a more selective extraction process resulting in a better end product, according to Soh. “We found that in our lipid extract, we had fewer pigments and less nitrogen,” which she says “will be better for combustion and it will create less NOx production. Once we transesterified, we were also able to find that the biodiesel we produced had basically the same properties as those produced using industrial solvents.”
To this point in her research, Soh says the challenges have been finding the right temperature and pressure conditions to make the process viable and occur in a reasonable amount of time. In addition to those challenges, she also points to the difficulty in finding a suitable solid catalyst that can be used to drive the reaction after the lipids have been extracted.
Zimmerman calls the research based on the idea of a one-pot algae biodiesel method the most significant accomplishment of her three-year-old lab. “The nice thing,” Zimmerman says, “is that you can actually recycle your CO2 so that when you are at industrial-scale and you release your pressure, you can actually capture that CO2 and recycle it for the next extraction.”