Alan (Al) W. Weimer is Clark Professor of Chemical and Biological Engineering at the University of Colorado, joining the faculty in 1996 after a 16-year career with the Dow Chemical Company.  For his solar thermal research, he received the 2005 U.S. Dept. of Energy Hydrogen Program R&D Award and the 2015 American Institute of Chemical Engineers Sustainable Engineering Forum Excellence in Research Award.  He served as CTO for Sundrop Fuels between 2008 and 2011.  He is named inventor on 42 issued U.S. Patents, has directed the research of 41 graduated and current Ph.D. students, and published 225 peer-reviewed journal articles.  He is a Fellow of the National Academy of Inventors.  His research interests include the design of solar-thermal chemical reactors and high temperature chemical processes with a focus on redox water and CO2 splitting.

Abstract

Two-step Solar-thermal Water Splitting - The Path Forward

Solar thermal water splitting (STWS) is a method for producing renewable hydrogen from water and concentrated sunlight using energy from the entire solar spectrum to directly drive the splitting reactions and, therefore, providing for high theoretical solar to hydrogen efficiencies.  In two-step STWS, a metal oxide is heated to high temperatures using concentrated sunlight until it reduces, forming a reduced product and O₂.  In a second step, H₂O re-oxidizes the material to its original state, forming H₂.  Various aspects of the operation of this process have been investigated since the 1970’s including the chemistry of the active redox material, which is reducing and oxidizing, the effects of redox operating conditions, and the solar thermal reactors in which the reactions occur. This presentation includes the current understanding and state of the field in each of these aspects and then provides a perspective on important future research directions. A primary focus is a continuous isothermal redox process using robust, low cost, and high productivity iron aluminate active materials.