Techno-economic design of a renewable energy-based reverse osmosis desalination system for an industrial area in Algeria: The case of Adrar's oil refinery

The depletion in the underground clean water reserve has necessitated the need for reverse osmosis (RO) water purification technique that is largely adopted especially in hydrocarbon industrial sectors to provide freshwater. In this study, an autonomous desalination system powered by renewable energy generators and a small-size diesel generator is proposed for an industrial area in Algeria. The main objective is to conduct TEE (Technical, Economic and Environmental) assessments of replacing the existing diesel energy-based RO stations in Adrar's oil refinery in the southern region of Algeria by a small renewable energy power plant. To achieve this, recent solar irradiation and wind speed data obtained from a weather station in Adrar were used to provide accurate assessment. Three scenarios (i.e., (i) the use of renewable energy generator only (ii) a mix of renewable energy and diesel generators and (iii) the use of diesel generator only) were created to meet the electrical power demand of the RO plant. Comparison was made among the scenarios in order to appreciate the use of renewable energy generators in contrast to the use of only diesel generator (the current practice in Adrar oil refinery). Two main mathematical indicators namely Total Net Present Cost (TNPC) and Loss of Power Supply Probability (LPSP), are established as fitness functions to ensure the optimal economic design and the continuous functioning of the RO water purification plant. A multi-objective Waterwheel Plant Optimization Algorithm based on sum of weight method was adopted to achieve the objective of the optimization problem. The proposed renewable energy-based RO system demonstrates competitive results. The first scenario show that the designed optimal system has a TNPC of 4.500e+4 US $ compared to 1.09e+5 US $ for the conventional system (i.e., current practice of using diesel generator only) aside the civil engineering costs. The second scenario proves that the integration of 10.340 kW of PV power to the system enables the reduction of the original diesel generator size to 52.310 % of its capacity there by saving 58.330 % of the yearly fuel consumption, and mitigating the CO2 emissions below 38.390% of compared to the conventional system. Sensitivity analysis was performed to test the robustness of the system in terms of cost and reliability when the system was subjected to fluctuations in renewable energy resources as well as variation in the costs of components. The analysis confirmed efficacy of the design approach in sizing cost-effective, reliable, and environmentally friendly renewable energy based-RO system for industrial use. This study is useful to the investors, policy makers and relevant government agencies at making an inform decision on the optimal energy source for clean water production for the RO plants in Algeria.