A one-dimensional model for flow-through porous electrodes operating above and below the limiting current of a metal deposition reaction has been developed. The model assumes there is one primary reactant species in an excess of supporting electrolyte and that a simultaneous side reaction may occur. The model predicts nonuniform reaction rates due to ohmic, mass-transfer, and heterogeneous kinetic limitations; the effects of axial diffusion and dispersion are included. Results are compared with the experimental data observed by various authors for the deposition of copper from sulfate solutions with the simultaneous generation of dissolved hydrogen. Satisfactory agreement between model predictions and experimental data on overall reactor performance and deposit distributions has been accomplished. For an upstream counterelectrode, distributions of reaction rate (for both single and multiple reactions), concentration, and potential describe the detailed system behavior.

Liquid solar fuels can be produced using a modular approach. A simplified economic analysis is used to evaluate the cost for making diesel and other fuels. In each reaction scheme, water is converted to hydrogen electrochemically, which is later converted to a liquid fuel by the Fischer-Tropsch method. Renewable energy sources, such as wind and solar, provide power to each process in its entirety. Furthermore, costs for photoelectrochemical cells, a developing hydrogen-production technology, are estimated and compared with electrolyzer costs at optimized current densities. This approach for evaluating renewable liquid fuels can be customized as new technologies develop and cost estimates evolve. One way to address the large capital costs associated with a large-scale conversion to renewable fuels is for the government to establish a guaranteed market to buy such fuels in an amount comparable to the needs of the military. This would also help the United States meet its own mandate for a 50% conversion of the fleet to nonfossil fuels by 2021.

A ferrite based oxygen carrier promoted with a mixed ionic–electronic conductor support is used in a hybrid solar-redox scheme. Based on both experiments and simulations, this scheme has the potential to co-produce liquid fuel and hydrogen from methane and solar energy at high efficiency with near zero life cycle CO2 emission.