Techno-economic analysis and optimization of standalone Hybrid Photovoltaic (PV)/Wind Turbine (WT) with water tank storage driven Reverse Osmosis (RO) desalination system

This study investigates the optimization of a Hybrid Renewable Energy System (HRES) integrated with water tank storage to power a Reverse Osmosis (RO) unit, tailored for the water demand scenarios in Dhahran city. The optimization employs a Differential Evolution (DE) algorithm to determine the optimal configuration of photovoltaic (PV) and wind turbine (WT) capacities alongside water tank volumes, aiming to minimize the Levelized Water Cost (LWC). Two scenarios are considered: constant and variable daily water demand. For the constant demand scenario (0.208 m³/day), the DE algorithm converges to an optimal configuration of 6.8 kW PV, 2 kW WT, and a 10.5 m³ water tank, achieving an LWC of $1.44/m³. Analysis reveals the system's capability to meet water demand year-round with varying tank storage and RO production levels, highlighting optimal performance during summer months due to increased solar energy availability. In the variable demand scenario, with an average daily water demand of 15 m³, the DE algorithm adjusts system capacities dynamically, resulting in a configuration of 12.4 kW PV, 7 kW WT, and a 42.8 m³ water tank. This adaptation ensures consistent water supply across fluctuating daily demands, achieving an LWC of $1.29/m³. Seasonal variations in the water tank's State of Charge (SOC) demonstrate higher efficiency during summer months, reflecting enhanced energy generation and storage capabilities. Surplus energy generated by the optimized system is effectively managed, either sold back to the grid or utilized to augment RO water production. Incorporating surplus energy for desalination purposes significantly reduces the LWC to $0.95/m³, showcasing substantial cost savings and improved system efficiency. The Loss of Water Supply Probability (LWSP), a new contribution of this study, is used to assess system reliability, ensuring an uninterrupted water supply in all demand scenarios. The environmental analysis demonstrates significant CO₂ emissions reductions, with a savings of 5 tons/year in the constant demand scenario and 12 tons/year in the variable demand scenario. Additionally, the cost of carbon capture is reduced by $550/year for the constant demand and $1320/year for the variable demand scenario. However, comparative analysis with prior studies underscores the economic competitiveness of the proposed HRES configuration, demonstrating superior LWC performance compared to existing literature.