STH Efficiency Prediction Platform


Sandia National Laboratories (SNL)

Capability Expert

Kevin Albrecht


Computational Tools and Modeling

Node Readiness Category

2: Solar Thermochemical (STCH)


The platform is a comprehensive computational tool for predicting solar to hydrogen (STH) efficiency of materials of known thermodynamic properties. A standardized two-step process with fixed component performance metrics allows for establishing the STH efficiency potential of a material based only on thermodynamics quantities. In addition, the platform consists of a library of component models, which can be reconfigured to investigate system design and component sizing for technoeconomic studies. Future iterations of these models will look to include kinetic and transport limitations as well as annualized performance of the solar field.

Capability Bounds‎

Currently, the model is focused on the use of nonstoichiometric oxide materials, which are the most likely candidates for high efficiency systems. The models are integrated with Ceria as a baseline material, but can be expanded to include novel perovskite oxide material formulations through generation of a material thermophysical property file. The efficiency limit is based on cascading pressure reduction through the use of high efficiency vacuum pumps, which has been identified as the most likely system configuration.

Unique Aspects‎

The rigorous accounting for all key aspects of two step thermochemical processes with standardized component performance metrics, allows for unsurpassed theoretical evaluation and comparison of candidate materials. The model allows for top-down guidance of material development with the end goal of high STH efficiency in mind. The component models and standard system configuration have been established from the most rigorous treatment identified in the literature to date and are continuously iterated on as the needs of the community and knowledge of reactor design and limitations change.


The code is currently being transitioned to the OpenModelica platform such that it can be viewed and refined by the user community. Material investigators will be equipped to establish the thermodynamic potential of their own materials through detailed user guides and standardized methods for integrating the new material thermodynamic property measurements into to the model. Extension of the code to capture new reactor designs, system configurations, and unique material compositions not captured in the current form will be undertaken as the needs of the community change.


This capability provides a standardized measurement for the theoretical STH efficiency, which is important in evaluating and comparing different water splitting materials. The model is also capable of performing sensitivity analysis on known material thermodynamics to guide future material investigations through targeting the most important thermodynamic quantities and changes required to meet efficiency targets.


"Efficiency Maximization in Solar Thermochemical Fuel Production: Challenging the Concept of Isothermal Water Splitting", I. Ermanoski, J. E. Miller, M. D. Allendorf, Physical Chemistry Chemical Physics 16 (2014) 8418.

"Annual average efficiency of a solar-thermochemical reactor", I. Ermanoski and N. P. Siegel, Energy Procedia 49 (2014) 1932.

"Cascading Pressure Thermal Reduction for Efficient Solar Fuel Production", I. Ermanoski, International Journal of Hydrogen Energy 39 (2014) 13114.