(96c) Modeling and Simulation of Solar-Fuel Generators

A solar-fuel generator is generally comprised of light absorbers, electrocatalyts, membrane separators and an electrolyte solution in a specific system geometry.  The overall solar-to-hydrogen conversion efficiency of such a system depends on the performance and materials properties of all the individual components as well as the design of the system.   The reactant and product transport in various cell configurations play a critical role in achieving optimal cell efficiency.  In this talk, I will introduce a comprehensive multi-physics model for a solar-fuel cell that accounts for the performance of photoabsorbers and electrocatalyts and the transport properties of electrolytes and membrane separators.  The whole cell model was employed to optimize geometries of prototype designs, to define operational conditions and constraints for various system designs, to provide target materials properties and to evaluate the viability of new design concepts.  Specifically, the operating voltage penalty associated with resistive loss, concentration overpotential, electrodialysis and the corresponding performance limits in various solution electrolytes will be discussed in detail.  A few novel cell designs, including a vapor feed device and a solar concentrator coupled solar-fuel cell will also be discussed.  In the past years, the close interaction between the modeling and experimental work has lead to a fully integrated, stable and scalable solar-hydrogen prototype that exceeds 10% conversion efficiency with gas separations.