Water-Responsive Materials for Evaporation Energy Harvesting

Xi Chen is an Associate Professor in the Nanoscience Initiative at the CUNY Advanced Science Research Center (ASRC) and the Department of Chemical Engineering at the City College of New York. He grew up in China and earned his B.S. and M.S. degrees from Tsinghua University, followed by a Ph.D. from Stevens Institute of Technology. Chen then completed a postdoc in Biological Sciences at Columbia University. Chen is recognized as a leader in hygroscopic materials by Blavatnik Regional Awards for Young Scientists and the NSF CAREER Award. He also serves as a World Economic Forum Expert in Future of Energy and Water. His current research focuses on deciphering powerful and efficient evaporation-induced mechanical deformations in biological systems and replicating these mechanisms outside the biological context for application in water-responsive locomotion, green chemistry, and evaporation energy harvesting. 

Abstract:

Many important physiological functions of living organisms (e.g., plant seed dispersal, bacterial spore activation) rely on water-responsive materials that mechanically deform in response to changes in relative humidity. Several of these mechanically robust, yet flexible structures can actuate more powerfully than existing actuators and muscles and they hold promise as efficient actuators for energy harvesting, adaptive structures, and soft robotics. Our recent progress in biological water-responsive materials has enabled the development of actuators with record-high actuation energy density, surpassing those of all known natural muscles. These high-performance water-responsive materials have led to the development of the evaporation energy harvesting devices that run autonomously when placed at a suitable air-water vapor interface. This allows for direct energy harvesting from naturally occurring or engineered water evaporation and subsequent conversion into mechanical energy or electricity. We see our evaporation energy harvesting system as highly unorthodox yet promising, and admittedly a high-risk, high-reward enterprise. If successful, it could unlock a previously unrecognized energy resource of water evaporation with power production potential comparable to that of current solar and wind farms, but at a much lower economic and resource cost, few intermittency issues, and with a high potential for public acceptance.