UT scientists design synthetic trees to secrete algal biofuel
April 8, 2013
r. Halil Berberoglu, an assistant professor in the Cockrell School of Engineering at The University of Texas at Austin, is leading a research effort to produce renewable biofuel using solar energy. To address the energetic and economic challenges of conventional algal biofuel production, Dr. Berberoglu, together with his Ph.D. student Thomas Murphy, have envisioned a novel system that mimics the way we obtain sap from a maple tree. In this case, instead of harvesting maple syrup, we would harvest biofuels from a synthetic tree.
In this concept, algae cells are grown as photosynthetic biofilms on porous surfaces that keep them hydrated and provide them with the nutrients they need for growing to maturity. Once the biofilm is matured, the supply of certain nutrients is stopped and the growth of cells is inhibited. At this point, the algae are provided with the necessary inputs to carry on photosynthesizing and secreting out energy dense molecules, such as free fatty acids. These are carried away from the cells in small channels mimicking the veins in plants and concentrated using evaporation-driven flows.
These concentrated energy-dense molecules can then be converted to a wide variety of biofuels. Once the algal biofilm reaches the end of its productive life over several months, it is removed, a new biofilm is grown to maturity, and the cycle continues. In this way, the available solar energy, water, and nutrients are directed more towards the production of fuel precursors and less towards growth, achieving a higher solar energy conversion and resource utilization efficiency.
Some of the initial work on developing algae biofilm cultivation was previously performed at Dr. Berberoglu’s laboratory by Dr. Altan Ozkan, a former Ph.D. student of Dr. Berberoglu and now an assistant professor at Bahcesehir University in Istanbul, Turkey. Drs. Berberoglu and Ozkan cultivated algae as biofilms on impervious surfaces under surface flow of nutrients in the laboratory. Moreover, they studied the fundamental aspects of algal cell attachment and formation of algal biofilms.
In the current work, Dr. Berberoglu and Mr. Murphy are focusing on the transport of nutrients, metabolites, light and thermal energy in the photosynthetic biofilms. For this Mr. Murphy has been developing computer models that couple light and mass transport with cellular kinetics for understanding and optimizing how these affect the productivity of the synthetic tree.
To further this technology, Dr. Berberoglu is also collaborating with Dr. Alexandre da Silva (UT ME) studying evaporative-driven transport of nutrient solutions in porous media, with Dr. Matt Posewitz of Colorado School of Mines who is genetically engineering algal strains to secrete the desired bioproducts, and with Drs. Lee and Brad Bebout of NASA Ames who are ecological experts working on improving the diversity of species in the photosynthetic biofilms.