Synergizing water desalination and hydrogen production using solar stills with novel sensible heat storage and an alkaline electrolyzer
Habib Ben Bacha, Abanob Joseph, A.S. Abdullah, Swellam W. Sharshir
Abstract
This study tested a cogeneration (desalination/hydrogen production) system with natural and black sand as sensible heat storage , considering the thermal efficiencies , environmental impact, water quality, cost aspects, and hydrogen generation rate. The black sand-modified distiller attained the highest water production of 4645 mL, more than the conventional distiller by 1595 mL. It also offered better energy and exergy efficiencies of 45.26 % and 3.72 %, respectively, compared to 32.10 % and 2.19 % for the conventional one. Both modified distillers showed impressive improvements in water quality by significant reductions in total dissolved solids (TDS) from 29,300 mg/L to 60–61 mg/L. Moreover, the black sand-modified still reduced chemical oxygen demand (COD) to 135 mg/L. The production cost was minimized by using black sand to 0.0111$/L, higher than one-fifth in the case of the lab-based distiller. Regarding hydrogen production , the highest rate was obtained using distilled water from a lab-based distiller of 0.742 gH₂/hr with an energy efficiency of 11.00 %; however, it was not much higher than the case of black sand-modified still (0.736 gH₂/hr production rate and 10.91 % efficiency). Moreover, the black sand-modified still showed the highest annual exergy output of 70.4 kWh/year, with a significant yearly decarbonization of 1.69 ton-CO 2 .