The approach that Thomas Murphy and Halil Berberoglu, researchers from the Mechanical Engineering Department at The University of Texas at Austin took, aimed to scale up algal biofuel production in order to increase the efficiency of the process.
The system that the researchers developed is called Surface Adhering Bioreactor (SABR), and it resembles the way nutrients are delivered in trees. The supply of nutrients and water to the growing algae are provided through porous surfaces, on which their are grown as biofilms. Once the maturity is reached, the supply of nutrients is stopped.
Reaching maturity means that the algae can produce energy dense molecules that are used in the production of various biofuels. The biofilms are suitable for fuel production for about three months, when they should be replaced by new biofilms. This ensures that the available nutrients, water and solar energy are not directed towards growing algae, but rather towards production of fuels.
When comparing the technology with existing cultivation methods, the scientists noted great improvements in efficiency. However, they pointed out that water loss through evaporation is a major limitation of the technique. This is also the next challenge, which the team is facing.