Water-energy nexus solutions for sustainable water pumping in semi-arid regions: A comparative techno-economic and environmental analysis of solar dish Stirling and photovoltaic systems

Reliable and low-carbon water pumping resources are essential to address freshwater scarcity in arid and semi-arid regions for domestic, agricultural, and livestock needs. Solar-driven pumping systems could provide a sustainable water pumping alternative. Hence, the current study presents a comparative Techno-economic and Environmental (3E) assessment of stand-alone Water Pumping Systems (WPSs) powered by solar Dish Stirling Engines (DSE) and typical flat Photovoltaic (PV) modules to supply a daily water demand of 45 m³/day. The main novelty of this current research lies in evaluating the DSE as an advanced substitute for conventional PV-based pumping, which demonstrates higher conversion efficiency, potential financial competitiveness, and reduced environmental impacts. The selected solar-powered pumping systems have been investigated using MATLAB/Simulink® software to determine the required power capacities, system sizing, and environmental-economic performance. The simulation results show that the designed PV system requires an installed capacity of 5.51 kW_p array, compared to the DSE, which requires 4.33 kW_p, with daily energy outputs of 11.77 kWh and 21.34 kWh, respectively. Economically, PV exhibits lower investment and operating costs, including a Present Value Cost (PVC), a levelized Cost of Electricity (LCOE), and a Water Discharge Cost (WDC) of around 9739 US$, 0.0884 US$/kWh, and 0.558 US$/m³, respectively. In contrast, the DSE system shows a PVC at about 12,900 US$ and an LCOE of 0.149 US$/kWh and also achieves a higher overall efficiency of about 26.48%. Furthermore, a detailed 3E sensitivity analysis has been conducted to examine the competitiveness of the adopted solar pumping schemes. Accordingly, the DSE demonstrates an attractive option at high power ratings, as well as at PV prices above 500 US$/kW_p. Replacing diesel-powered pumping with solar-based alternatives will provide substantial reductions in harmful Carbon Dioxide (CO₂) emissions. The avoided CO₂-damage cost increases linearly with solar resource availability, rising from approximately 85 to 425 US$/year for PV as GHI increases from 2 to 10 kWh/m²/day, and from 135 to 680 US$/year for DSE over the same range of DNI. Overall, the obtained simulation results will provide valuable implications and clear policy-relevant guidance for the durable water-energy nexus framework in order to select the cost-effective, sustainable, and reliable water pumping technologies in semi-arid regions.