Quantifying Energy Water Footprints for Unified Analysis in the Water-Energy-Food Nexus

Water footprint assessment is a critical tool for understanding the sustainability of energy production within the water-energy-food nexus. This study presents a detailed methodology for quantifying the water footprint of various energy sources, including coal, oil, natural gas, and renewable energy systems such as solar, hydropower, and bioenergy. The methodology incorporates water usage across all stages of energy production: extraction, processing, and power generation. Additionally, it emphasizes the need to unify the measurement units across the water, energy, and food sectors by leveraging the water footprint concept, enabling a more integrated analysis of the nexus model.

Key factors considered in this study include water demand per unit of energy (e.g., m³/GJ), type of cooling technology (open-loop, closed-loop, and dry cooling), regional water stress indices, and energy conversion efficiencies. A life-cycle assessment (LCA) framework is adopted to evaluate the environmental impact of each energy source, with adjustments made for region-specific water availability and climatic conditions. While much evaluation of water footprints has been carried out in water and food sectors, energy-related water footprint studies are still limited.

This study highlights the potential for reducing water consumption and improving resource efficiency in energy production through systematical calculations and comparison of water footprints across sectors. The unified water footprint metric facilitates a more comprehensive understanding of the interdependencies within the water-energy-food nexus, allowing for the identification of trade-offs and synergies. This approach also provides policymakers and resource managers with critical data to prioritize sustainable strategies for energy production and resource allocation, particularly in water-stressed regions. The findings underscore the importance of integrating water footprint data into nexus modeling and decision-making processes to ensure a balanced and sustainable approach to resource management in the face of growing global demand.

Acknowledgement: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-RS-2023-00280330).