LANL innovation: Harvesting concentrated biofuel from algae

August 4, 2011—Scientists are optimizing the R&D 100 award-winning Ultrasonic Algal Biofuel Harvester to obtain concentrated biofuel from algae.

A significant challenge to acquiring biofuel from algae is cheaply separating the algae from the very thing that allows it to grow: water. Microalgae usually are grown under dilute cultivation conditions in a typical cell density of less than 1 gram per liter of water (999 parts water to 1 part algae).

Adding to the problem of removing so much water is scale. The optimal size of the commercial "open-pond" algae production facility is envisioned at more than a million liters of culture. Therefore, the harvesting technology must concentrate the algae cheaply, effectively, and with a robust flow-through rate.

Using sound waves

The Ultrasonic Algal Biofuel Harvester works at select sound wave frequencies to focus and concentrate the fluid-borne algal cells. Then the harvester exposes the concentrated algae to different frequencies to break open the cells, release the lipids, and separate the oils, proteins, and water from one another. The researchers are optimizing and integrating the individual processes into a single device.

Cost effective, energy-efficient

Based on their lab-scale devices, the researchers believe that they can develop a portable, energy-efficient, ultrasonic algae harvesting device to concentrate 25 gallons of algae per hour for less than a penny per gallon of lipid. Such an improvement would drastically reduce the cost of separating water from algae.

Babetta Marrone of the Laboratory's Advanced Measurement Science leads a team of James Coons and Thomas Yoshida of the Lab's Chemical Diagnostics and Engineering and Taraka Dale and Daniel Kalb also of Advanced Measurement Science to develop the harvester. The DOE Office of Energy Efficiency and Renewable Energy, National Alliance for Advanced Biofuels and Bioproducts (NAABB) algae consortium and industry partner Solix Biosystems fund the work, which supports the Lab’s Energy Security mission area and the Materials for the Future science pillar.