A smart aquaponic prototype for urban agriculture: design, operation, and preliminary water–energy–food nexus assessment

Rapid urbanization and increasing pressure on water, energy, and food (WEF) resources emphasize the need for resource-efficient urban agriculture systems. This study developed and preliminarily evaluated a smart aquaponic prototype (Smartponic) integrating reused plastic bottles, environmental monitoring, fish production, lettuce, and microgreens. The assessment combined short-term operational observations with annualized performance projections and literature-derived benchmarks. Performance was evaluated using water productivity, energy productivity, food yield, and an exploratory WEF nexus comparison. Under the adopted annualization assumptions, Smartponic was estimated to produce 249.6 kg/year of food using 1,164 L/year of water, corresponding to a water productivity of 214.43 kg/m3, with an estimated electricity consumption of 3,139 kWh/year. Literature-derived conventional systems were used only as contextual benchmarks. Results indicated high projected water productivity but greater operational energy demand, highlighting an important water–energy trade-off. Further long-term validation, energy optimization, and economic evaluation are required.