Design for sustainability: An integrated pumped hydro reverse osmosis system to supply water and energy for mining operations

The mining industry is water and energy-intensive and has significant environmental impacts due to its reliance on fossil fuels. Integrating pumped hydro energy storage with a reverse osmosis plant powered by renewables could improve its sustainability. The present study assesses the feasibility of implementing a system to supply fresh water and clean energy to the mining industry of the Atacama Desert in northern Chile, using design equations, cost models, and global sensitivity analysis. The novelty of the study consists in developing a model that considers the technical, economic, and environmental aspects of putting this integrated system for mining operations in place. The results show that the levelized costs of this system to supply water and energy reach 3.20 US$·m⁻³ and 87.04 US$·MWh⁻¹, respectively. Operating separately, the costs are 4.73 US$·m⁻³ for water and 48.96 US$·MWh⁻¹ for energy. When powered by renewable energy instead of the national grid, greenhouse gas emissions are reduced from 660.58 to 143.16 ktCO₂eq·y^-1, making it a competitive and environmentally friendly option. Global sensitivity analysis identified prices of electricity and steel, and the reverse osmosis plant capital cost as the variables exerting the strongest impact on the levelized cost of water supply. Meanwhile, for the levelized cost of energy supply, the variables exerting the strongest impact are the photovoltaic farm capital and operational cost, and the pump as a turbine device capital cost. Therefore, to achieve a substantial reduction in the levelized costs, efforts should focus on these variables.