Experimental study on sewage water for clean water and hydrogen production using heat pump-driven solar still and alkaline electrolyzer

The current work concentrates on offering distilled water as a substitute water source for the electrolysis process. In place of the laboratory water distiller, the heat pump solar still (HPSS) was introduced during the work to distill sewage water. Additionally, a comparison is made between the treated water-based electrolyte's performance and that of the standard electrolyte based on the energy, exergy, and cost of water. The production of hydrogen, energy, and exergetic efficiency and the influence of each electrolyte on the electrode material are then compared for the two types of water during the electrolysis process. Finally, both electrolytes are examined at different cell voltages. The HPSS unit provided 12.48 L/m² of distilled water after an operation period from 9:00 to 21:00, with energy efficiency 4.91 % higher than the water distiller and 3.88 % lower exergy loss than the laboratory water distiller. When comparing the two water types, the electrolysis process showed that the hydrogen productivity reduction was only 5.2 % as the production rate was 0.742 gH₂/hr and 0.704 gH₂/hr for the case of standard distilled water and treated water, respectively. When the voltage increased from 6.66 V to 9.5 V, the hydrogen production rate increased by 21.84 % for the standard electrolyte and 22 % for the treated water-based electrolyte. Conversely, the energy efficiency declined by 29.8 % and 29.7 %, respectively.