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NexSym – a tool for simulating the Water, Energy and Food nexus

The Water-Energy-Food nexus means that the security of water, energy and food are linked closely with one another. As such, actions in one area can have a profound effect on one or both of the other areas, and thus solutions that secure resource supplies and meet demands must be integrative and sustainable.

NexSym is a Nexus Simulation System which can be used to assess the sustainability of a local production system for food, energy, water and possibly other goods and services that is predominantly for the purpose of meeting the demands of the local population. Compared to other tools for assessing energy-food-water systems, this tool focusses on the local/ regional scale and hence provides detailed predictions for any given specific design (in terms of the choice of technological options, scale of operations, and connections between the technological system components and ecosystem components).

NexSym advances the state-of-the-art in nexus tools by explicit dynamic modelling of local techno-ecological interactions relevant to WEF operations. The tool is modular, and integrates models for ecosystems, WEF production and consumption components. It also allows the user to build, simulate and analyse a “flowsheet” of a local system.

This clarifies critical interactions and enhances knowledge and understanding that supports innovative solutions by balancing resource supply and demand and increasing synergies between components, while maintaining ecosystems.

NexSym is particularly useful in exploring potential improvement options before comprehensive optimisation is carried out, or for validating and analysing specific optimisation results within a wider context of a local system

In use

NexSym allowed assessment of the synergistic design of a local nexus system in a UK eco-town. The conceptual design was predicted to improve local nutrient balance and meet 100% of electricity demand, while achieving higher carbon capture and biomass provisioning, higher water reuse and food production, however with a remarkable impact on land use. This study was reported in Martinez-Hernandez, E., Leach, M., & Yang, A. (2017). Understanding water-energy-food and ecosystem interactions using the nexus simulation tool NexSym. Applied energy, 206, 1009-1021.