Performance improvement of double-slope solar still using locally sourced sand, coupled with glass cooling integration

• Minerals extracted from black sand are used as an alternative sensible heat storage . • Black sand minerals with cover cooling boost productivity by up to 80.96 %. • Thermal efficiency is enhanced by 81 % and exergy by 102 %. • Cost of freshwater reduced by 43 %, to 0.0102$ per liter. • Carbon dioxide reduction of up to 2.10 tons is achieved. The performance of traditional solar stills (SSs) is often hindered by inefficiencies and low rates of freshwater production. This study proposes a novel approach to enhance the performance of double slope SSs by incorporating environmentally friendly and recovery-based features. Minerals derived from black sand are suggested as sustainable alternatives to synthetic nanofluids and conventional heat storage materials. Four configurations of SSs are examined: one with natural black sand, one with black sand and a glass cover cooling, one utilizing minerals from black sand for sensible heat storage, and a final configuration combining these minerals with glass cooling. A comprehensive analysis is conducted to evaluate the energy, exergy, cost, and environmental performance against a conventional SS. The findings indicate significant improvements in efficiency and productivity. The use of natural black sand increased freshwater production by 35.45 %, while thermal and exergy efficiencies improved by 35 % and 58 %, respectively. The application of glass cooling resulted in a 59.46 % increase in freshwater production, alongside a 59 % enhancement in thermal efficiency and a 75 % improvement in exergy efficiency. When black sand minerals were employed, productivity rose by 63.6 %, with thermal efficiency increasing by 62 % and exergy efficiency improving by 104 %. The combination of these minerals with glass cooling led to a remarkable 80.96 % increase in productivity, with thermal efficiency reaching 52.44 % (81 % improvement) and exergy efficiency climbing to 3.31 % (102 % enhancement). The analysis underscores the sustainability of this system, as it reduces the cost of freshwater by 43 % and decreases CO 2 emissions by 2.10 tons.