Mohsen Nowrouzi

The potable water supply crisis is one of the most critical environmental challenges facing humanity on a global scale. To address this issue, this study was conducted to compare the economic and environmental burdens of energy supply for a designed Reverse Osmosis System (ROS) powered by fossil fuels (Scenario 1: fossil energy supply, FE) versus solar energy (Scenario 2: fossil + solar energy supply, SE) in Larestan city, Iran. The results showed that the ROS significantly reduced water ions (by 86%), total dissolved solids (98%), electrical conductivity (97.3%), and NaCl (96.4%). Although the second scenario increased the initial capital cost by 38% compared to the first scenario, it substantially reduced environmental impacts by 20% to 73% across all categories. Under the SE scenario, the burdens on human health, ecosystems, and resources were reduced by a minimum of 43.2%. The major sources of environmental burdens in the ROS were greenhouse gas emissions (particularly CO2 and CH4), electrical conductivity, and the high temperature of the rejected water. Sensitivity analysis confirmed a 48% reduction in environmental impact under the SE scenario compared to FE. Moreover, Monte Carlo simulation revealed a coefficient of variation of less than 7% for all environmental categories, indicating the reliability and precision of the results. According to the Life Cycle Cost (LCC) analysis, the costs of water production, capital investment, and operation in the SE were 7%, 21%, and 11% higher, respectively, than those in the FE scenario. However, over a 20-year horizon, the net present value and the payback period exhibited increases of 9.34% and 1.3%, respectively, in the SE scenario relative to the FE scenario. Although the SE increased the economic costs to some extent, it significantly reduced environmental burdens. Therefore, this study provides a strategic guideline for utilizing renewable energy in water supply systems.