Energy–Water–Profit Trade-Offs and Scale Economies in Urban Aquaponics Under Electricity Unreliability: Comparative Evidence from Lagos and Abuja, Nigeria

Abstract

Urban aquaponics is increasingly promoted as a climate-smart and resource-efficient food production system, yet its economic viability under unreliable electricity conditions remains poorly understood in emerging-market contexts. This study evaluates energy–water–profit trade-offs and scale economies in urban aquaponics systems across Lagos and Abuja, Nigeria. Using system-level socio-technical and financial data from 18 operational units, we construct integrated food–energy–water (FEW) performance indicators, conduct electricity shock simulations, and estimate econometric models to identify the drivers of profitability. Results reveal strong scale economies. Semi-commercial systems exhibit higher profit margins (≈50–54%), shorter payback periods (≈2.3 years), and substantially greater profit per kWh compared to household systems. Energy intensity per unit output declines by up to 50% with scale, while water productivity (profit per m³) more than doubles in larger systems. Sensitivity analysis indicates that household systems become unprofitable at electricity tariff increases of approximately 2.5× baseline or under moderate outage escalation, whereas semi-commercial systems remain viable even under substantial tariff and diesel price shocks. Elasticity analysis demonstrates that capital intensity is the dominant profitability driver: a 1% increase in capital investment increases profit by approximately 0.85%, while land area and energy use are not independently significant once capital is controlled. These findings suggest that profitability and resilience are structurally capital-driven rather than determined by system size alone. The study contributes to FEW nexus scholarships by empirically demonstrating that scale moderates’ energy–water–profit trade-offs under infrastructure instability. Policy implications highlight the importance of capital access, renewable energy integration, and scale-sensitive support mechanisms for enhancing urban food system resilience in electricity-constrained environments