Sustainable solar still desalination using beeswax and paraffin wax phase change materials: A 5E comparison toward emerging efficient systems

• 5E performance of beeswax (BWSS) & paraffin wax (PWSS) solar stills is studied. • BWSS showed 8.7% higher daily productivity compared to PWSS. • Energy/exergy efficiency of BWSS was 6.7%/6.1% higher than PWSS. • Production cost/payback period of BWSS was 7.7%/4.9% lower than PWSS. • CO 2 mitigation and credit carbon earning of BWSS was 10.2% higher than PWSS. The existing literature provides limited investigation into the use of beeswax as a phase change material (PCM) in solar still applications, and a direct comparative analysis with paraffin wax under identical climatic conditions has yet to be thoroughly explored. This study addresses this gap by evaluating the potential of beeswax as a sustainable and effective alternative to conventional paraffin-based PCMs. To this end, a comparative experimental assessment was conducted using solar still desalination systems integrated with either beeswax (BWSS) or paraffin wax (PWSS), and analyzed through a comprehensive 5E framework of energy, exergy, economic, environmental, and enviro-economic perspectives. The results demonstrated that BWSS outperformed PWSS in daily productivity by 8.7%, energy efficiency by 6.7%, and exergy efficiency by 6.1%. Economically, BWSS achieved a 7.7% lower cost of production, a 4.9% shorter payback period, and a 7.9% higher profit-cost ratio. Environmentally, BWSS led to a 10.2% increase in CO 2 mitigation and carbon credit earnings over a 10-year operational period. While the sustainability index showed a modest 0.1% improvement for BWSS, this nonetheless indicates greater alignment with sustainable freshwater production objectives. These findings support the integration of beeswax as a promising PCM for solar still enhancement, particularly in systems aimed at achieving higher efficiency, economic viability, and reduced environmental impact. The study contributes to broader sustainability goals by advancing the development of low-cost, renewable, and high-performance thermal energy storage solutions for decentralized desalination technologies.