Use of hybrid renewable energy system with organic photovoltaic cells in zinc electrowinning

This work evaluates the use of customized hybrid renewable energy system (HRES) with organic photovoltaic (OPV) cells for producing a high-purity metal by electrowinning. This process usually represents the most energy intensive step in the mining industry. A key advantage about the developed system is that the electric charge is inherently generated as direct current (DC), which can be directly supplied to the electrowinning cells without using intermediate rectifiers. This approach eliminates the energy losses associated, thus increasing the overall efficiency of the power system, and decreases the carbon footprint of the industrial facility. In this context, the main purpose of this first work was to evaluate the energy saving performance of the technology and its application to produce a quality product, which was characterized by morphology, crystal structure and bending behavior. The electrowinning of zinc was selected as case study. Thus, zinc electrodeposition tests were conducted under conditions practiced in industrial operations. The results demonstrated the proper functioning of the HRES system, since constant DC current was supplied to the process. The zinc cathodes exhibited morphology and structure typically described in the literature, which were ductile enough to allow bending without fracturing. On days with global horizontal irradiances in the range from 100 W m(-2) to 1200 W m(-2), 26 +/- 4% of the total current supplied to the electrowinning cell was generated by the OPV cells used in this work. In Brazil, this performance corresponds to carbon mitigation of about 6.4 x 10(-2) tons of carbon dioxide equivalents (CO2 eq) per ton of zinc produced. These findings indicate that hybrid systems with photovoltaic cells represent an alternative to save energy and increase the sustainability of electrowinning processes. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study evaluated the use of a customized hybrid renewable energy system with organic photovoltaic cells for electrowinning high-purity metals, demonstrating the system's ability to provide constant DC current and generate zinc cathodes that can be bent without fracturing. It was found that 26 +/- 4% of the total current supplied to the electrowinning cell was generated by the OPV cells, leading to a carbon mitigation of about 6.4 x 10(-2) tons of carbon dioxide equivalents (CO2 eq) per ton of zinc produced in Brazil. Overall, the findings suggest that hybrid systems with photovoltaic cells are a promising alternative for saving energy and enhancing the sustainability of electrowinning processes.