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Two New Investigator Awards Support Research on Desalination Technology and Metabolic Rate Processes of Plants

Lichao Cai
First-year graduate student Lichao Cai looking at a small vial containing a slurry of clathrate hydrates.

The Grand Challenges Program has awarded two New Investigator Grants for 2011-2012. One will support a proposal by Michael Bender to develop new methods of measuring plant respiration and photosynthesis rates. The other, led by Sankaran Sundaresan, will fund research to create a new hydrate-based desalination technology. The new projects will further diversify the scope of research and teaching that takes aim at dimensions of the climate and energy problem under the umbrella of the Siebel Energy Challenge. 

"These projects are admirable examples of the objectives of the Grand Challenges initiative," said Rob Socolow, Director of the Siebel Energy Challenge and professor of mechanical and aerospace engineering. "Both provide fresh perspectives on critical problems in environmental and energy sciences and, at the same time, create innovations in the undergraduate curriculum and enable undergraduate research opportunities."

Michael Bender, professor of geosciences, will collaborate with Professor Kevin Griffin, a plant physiologist at Columbia University, to test a series of fundamental hypotheses relevant to the modeling of the terrestrial carbon cycle. In the context of global change and rising levels of atmospheric carbon dioxide, photosynthesis and respiration rates are evolving in ways that are intimately linked to the changing state of the biosphere.

As part of the proposed research, the team will implement a new oxygen concentration and isotope labeling method to investigate a number of basic plant physiology questions. The innovative experimental setup will allow Bender and colleagues to make rapid and high-precision measurements of gross oxygen production and consumption by plants, and therefore conduct systematic experiments constraining rates as a function of irradiance, carbon dioxide, and other properties.

Studies of plant physiology represent a major new area of research for members of the Bender group. This proposal expands on the group’s research, begun decades earlier, measuring rates of photosynthesis and respiration in phytoplankton. It will also leverage tracer approaches and ultra-high precision mass spectrometry.

With this award, Bender will acquire a state-of-the-art Picarro cavity ringdown spectrometer designed to make continuous and high precision measurements of the carbon dioxide concentration of outside air as well as its isotopic composition. The instrument will be incorporated in undergraduate teaching labs across campus and used for independent research projects.

Sankaran Sundaresan, professor of chemical and biological engineering, will collaborate with departmental colleagues Pablo Debenedetti, professor and Vice Dean of the School of Engineering and Applied Science, Brian Pethica, senior scientist, and Rodney Priestley, assistant professor, to carry out novel research and education initiatives related to desalination. As one in six human beings living today lacks adequate access to water, and more than twice that number lack basic sanitation, there is an urgent need to develop affordable technologies to satisfy the world’s ever growing demand for potable water.

Sundaresan and colleagues seek to provide a low-cost and low-emission global source of fresh water by exploring the potential of a new clathrate hydrate-based desalination technology. Clathrate hydrates are crystalline materials consisting of water cages of different sizes in which the guest hydrate former molecules reside. In this promising technology, cold deep seawater is contacted with hydrate formers, for example a small molecule such as methane, dissolved in a liquid stream of a heavier hydrocarbon, under conditions that promote condensation of the water molecules around the hydrate formers. The resulting salt-free hydrate crystals are then separated from the brine, and melted via heat exchange with warmer sea surface water. By using the cold deep seawater to form the hydrates and warmer surface water to melt them subsequently, the research seeks to minimize the total energy cost associated with this technology.

This proposal will leverage Sundaresan’s experience with building multiphase systems and process design, Debenedetti’s expertise in thermodynamics, and Pethica’s knowledge of physical chemistry. Together, they will first identify the most desirable combination of hydrate formers and processing conditions that would optimize the nucleation, growth, and stability of the hydrate crystals, and then develop process design concepts based on these findings.

To integrate this new research into the undergraduate curriculum, Priestley, Sundaresan, and Debenedetti will add design case studies on desalination technologies to the introductory chemical engineering course CBE 245.

These two new grants were awarded from a competitive pool of projects following a campus-wide call for proposals. Since 2007, the Grand Challenges Program has provided seed funding of up to $100,000 per year for two years to support new directions in faculty research with connections to the Grand Challenges themes. Over $6.0 million has been awarded to date involving more than 50 faculty committed to exploring new dimensions in their research and teaching activities.

Launched in 2007, the Grand Challenges Program is an integrated research and education initiative that seeks to develop solutions to focal problems of energy and climate, sustainable development in Africa, and global health and infectious disease. A collaboration between the Princeton Environmental Institute, the School of Engineering and Applied Science, and the Woodrow Wilson School of Public and International Affairs, it is supported by the High Meadows Foundation, the Princeton Environmental Institute and the Thomas and Stacey Siebel Foundation. The Grand Challenges Program is administered by the Princeton Environmental Institute.