Renewable energy powered membrane technology: Power control management for enhanced photovoltaic-membrane system performance across multiple solar days

In a directly-coupled photovoltaic-powered membrane desalination (PV-membrane) system, the solar power supply must exceed a certain threshold for the pump to generate sufficient hydraulic pressure to overcome the membrane's osmotic barrier. Below this threshold, no appreciable membrane flux is produced, meaning PV power is underutilised or dissipated by the system. In this work, a power control management system (PCMS) is designed to harvest the underutilised PV power into a supercapacitor (SC) to, firstly, buffer the periods of solar irradiance fluctuations during daily operation. Secondly, this also fosters a continuous stable operation of the PV-membrane system across multiple solar days. The investigation compared the performance of the PCMS against two other configurations: “directly-coupled” (passive, no SC) and “semi-active” (with SC, but no PCMS). During a three-day test desalinating brackish water (5 g/L salinity), the PCMS enabled an improvement in water quality, with the permeate electrical conductivity (EC) 46% and 23% lower than the other configurations, respectively. The specific energy consumption (SEC) was reduced by 18% and 6%, respectively, during the same period. ... mehrDuring a week-long experiment, the PCMS facilitated the production of 6218 L of potable water at an average EC of 0.52 mS/cm, while maintaining a minimum state-of-charge of the SCs to about 40%, allowing for subsequent use. The system also achieved a maximum load-matching efficiency of 99.6%, surpassing the 94.7%–96.6% observed in the other configurations. These results pave the way for maximising daily PV energy utilisation, ensuring steady and dependable clean water production for the community and improving the water-energy nexus.