ASU wins $1Mil DOE algae research grant
November 16, 2015
he U.S. Department of Energy (DOE) has awarded Arizona State University (ASU) a three-year, $1 million grant to fund the Atmospheric Carbon Dioxide Capture and Membrane Delivery project aimed at enabling more large-scale cultivation of microalgae.
ASU engineer Dr. Bruce Rittmann and physicist Dr. Klaus Lackner will lead a new research project to aid (DOE) efforts to boost production of a promising source for clean, renewable energy. “Our goal is to develop systems to make growing microalgae more affordable and sustainable and to produce it on scales large enough to meet growing demands in the United States and globally,” Dr. Rittmann said.
He and Dr. Lackner are professors of civil, environmental and sustainable engineering in the School of Sustainable Engineering and the Built Environment, one of ASU’s Ira A. Fulton Schools of Engineering. Dr. Rittmann is director of the Swette Center for Environmental Biotechnology at ASU’s Biodesign Institute. Dr. Lackner is director of ASU’s Center for Negative Carbon Emissions.
Their centers will join forces with researchers in the Arizona Center for Algae Technology and Innovation (AzCATI) on atmospheric CO2 enrichment and delivery systems. AzCATI, located at ASU’s Polytechnic campus, is part of the School of Sustainable Engineering and the Built Environment.
The project team will focus on two technologies: moisture swing sorption for capturing CO2 from the atmosphere and membrane carbonation for delivering the CO2 more efficiently to microalgae.
“The current atmospheric levels of CO2 are too low to produce high rates of microalgae growth. We want to feed the microalgae with CO2 concentration significantly higher than in the atmosphere to enable the microalgae to grow much faster. My part of the project is about a novel way to deliver that additional CO2 at very high efficiency,” Dr. Rittmann said.
“Because atmospheric CO2 is everywhere, our goal of linking CO2 enrichment and delivery will enable microalgae technology to work in any sunny climate or environmental condition,” said Dr. Lackner.
Microalgae grows best in the sunny, warm climate of the Southwest, but need a source of concentrated CO2 to grow. Power plant emissions are a potential source of concentrated CO2, but there are not power plants near most good locations for growing microalgae. Capturing and delivering CO2 directly from air is a game changer, Drs. Rittmann and Lackner said, because it allows microalgae to grow anywhere to make fuels and valuable products.
Dr. Lackner’s part of the project involves a new technology called moisture swing sorption, which uses a special material that, when dry, selectively adsorbs CO2 out of the air to enrich atmospheric CO2. When the material gets wet, it releases the CO2 into a small volume of air so that CO2 is at least 100 times more concentrated than it was in the ambient air.
Dr. Lackner’s approach will be augmented by another technology, membrane carbonation, which provides a method to deliver more CO2 to microalgae much more efficiently than the conventional method. This method, called sparging, works much like the way bubbles carry oxygen into the water in a fish tank.
Dr. Rittmann’s membrane material has no pores, so bubbles are not formed. Only individual CO2 gas molecules can pass through the walls of the membrane by diffusion. CO2 is then rapidly dissolved in liquid so it can be “inhaled” by the algae.
Bubbles, on the other hand, rise rapidly and allow the CO2 to escape back into the atmosphere before it can be “inhaled” by the algae, which reduces efficiency and increases costs. “We can get a much higher CO2-use efficiency by membrane carbonation. This is important when we capture and concentrate the CO2, which has a cost,” Rittmann explains.
To help meet the ambitious goals and milestones of the project, the Biodesign Institute’s Center for Applied Structural Discovery (CASD) is also supporting the project through the efforts of researcher Justin Flory, who will serve as the technical project manager.