Techno-economic analysis of a photocatalytic industrial plant using a novel Au-TiO2 photocatalyst

One of the most debated topics in recent years is the greenhouse effect caused by fossil fuels combustion, with consequent carbon dioxide emissions into the atmosphere. It is now undoubted that this effect is a threat to the entire biosphere, including humans. To overcome this challenge, a transition to cleaner energy technologies is needed. One promising technology is photocatalysis, which allows the direct conversion of solar energy to chemical energy in the form of hydrogen, which can then be stored. In this framework, the present study proposes a preliminary techno-economic analysis of an industrial plant for photocatalytic hydrogen production via water splitting. The photocatalyst considered for the analysis was developed by the start-up StarLIGH2T and it is an innovative catalyst that can harvest up to 90% of the solar spectrum, compared to 5% for traditional catalysts on the market. The Solar-To-Hydrogen (STH) efficiency of the selected photocatalyst was obtained from lab-scale experimental data. This efficiency was imported into MATLAB®, together with the irradiation data reported on PVGIS, to find the exposed surface of the photocatalytic reactors required to produce the target amount of hydrogen, fixed at 365 tons per year. Using this value and fixing the solar irradiance hitting the reactors at a design value of 1000 W/m2, the corresponding design hourly rate of hydrogen production was calculated. The design rate was then imposed as an input parameter into a system simulation performed in Aspen Plus®, in order to size the compressors and the heat exchangers that are needed downstream of the photocatalytic reactors to bring the produced hydrogen to the desired conditions. Subsequently, a coupled Simulink®-Aspen Plus Dynamics® simulation was used to calculate the hydrogen produced and the electrical energy consumed by the equipment during one year of effective solar irradiation. More specifically, Simulink® was used to generate the inputs and to rework the outputs, while Aspen Plus Dynamics® had the purpose to perform the calculations. Finally, the economic analysis was performed using well-established cost functions from chemical engineering textbooks. Thanks to this techno-economic analysis, the key aspects of this new technology have been explored allowing us to highlight the crucial parameters necessary to make it industrially competitive.