Water–Energy–Food Nexus and Circular Economy Analysis of Melon (Cucumis melo L.) and Grape (Vitis vinifera L.) Value Chains: A Life Cycle, Water Footprint, and Exergy Assessment with Turkish Case Studies

ABSTRACT: This study applies an integrated water–energy–food (WEF) nexus approach to melon and grape value chains, combining life cycle assessment, water footprinting (blue/green/grey), carbon footprint, and exergy analysis within a circular economy framework. Türkiye, the fourth-largest melon producer (~1.7 Mt/yr) with over 80 indigenous grape cultivars, serves as the primary case study, supplemented by global data. In the wine chain, cultivation (37%) and glass packaging (28%) dominate global warming potential (GWP), with a baseline of 1.38 kg CO₂eq per 0.75 L bottle (ReCiPe 2016-H). Recovering pomace bioethanol, polyphenolic extracts, grape seed oil, and tartaric acid in a circular economy scenario lowers the footprint to 1.12 kg CO₂eq (−19%). Turkish wine grapes exhibit blue-water shares of 38–41%, well above the global 25%, reflecting irrigation reliance in semi-arid Anatolia (Elazığ, Diyarbakır, Cappadocia). Exergy analysis identifies refrigeration as the top energy sink (280 MJ/t grapes, 32%) and primary exergy destruction site (193 MJ/t; second-law efficiency: 31%). Fermentation records the lowest exergy efficiency (28%) due to the irreversibility of sugar-to-ethanol conversion. These findings demonstrate that combining WEF nexus management with circular bioeconomy strategies can substantially reduce the overall environmental burden, particularly in water-stressed agricultural regions.