Systematic Analysis and Optimization of Water-Energy Nexus
Spyridon D. Tsolas (1), M. Nazmul Karim (1), M. M. Faruque Hasan (1)
1. Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843, USA.
We present a scalable and systematic method for the design and optimization of complex water-energy nexus using graph theory-based network representation and a novel water-energy nexus (WEN) diagram. The graph-theoretic approach defines a nexus as a directed bipartite graph with two product flows, namely water and energy. The network representation allows decomposing a complex nexus into essential and redundant components. We show that for specified external grid demands, the optimal nexus configuration with minimum generation is the one without any redundant subgraphs with closed cycles. We then propose a systematic method to identify and eliminate redundant cycles, flows and entities within a nexus leading to (i) minimum generation/extraction of water and energy resources from the environment, or (ii) maximum yield of water and energy to meet external demands. Our proposed graphical approach is simple to implement and results in optimal nexus configurations. The approach is demonstrated using case studies on national and regional water-energy systems.
Keywords: Water-Energy Nexus, Optimization, Water-Energy Diagram, Source-Sink Network