event 22 Aug 2018

Food-Energy-Water Nexus // A Life Cycle Analysis on Virtual Water and Embodied Energy in Food Consumption in the Tamar Catchment, UK

By Gloria Salmoral, Xiaoyu Yan. Evaluations of food, energy and water (FEW) linkages are rapidly emerging in contemporary Nexus studies. This paper demonstrates, from a food consumption perspective, the potential of life cycle thinking in understanding the complex and often “hidden” linkages between FEW systems.

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https://flic.kr/p/RaAoXT (C) Richard B Clark / Flickr

This study evaluates the upstream virtual water and embodied energy in food consumption in the Tamar catchment, South West England, distinguishing between domestic production and imports origin. The study also evaluates key inputs, including virtual nutrients and animal feed, when tracking supply chain of food products. Based on current dietary patterns and food products selection, the catchment consumes annually 834 TJ, 17 hm3 and 244 hm3 of energy, blue water and green water, respectively. Tamar is not self-sufficient in terms of food and requires imports of food products, as well as imports of virtual nutrients and animal feed for local production.

Consequently, 51% of the embodied energy and 88% blue and 45% green virtual water in food consumed within the catchment are imported. Most of the embodied energy (58%) and green virtual water (90%) are because of animal feed production, where nearly half of embodied energy (48%) and green virtual water (42%) come from imports. 92% of blue virtual water is used for irrigation and primarily happens elsewhere due to imports. Irrigation is the process that demands the largest amount of energy for the crop-based products, with 38% of their total energy demand, followed by fertilisers production (24%).

This study illustrates water and energy hotspots in the food life cycle and highlights potential FEW risks and trade-offs through trade. This is useful considering potential unexpected changes in trade under recent global socio-political trends. Currently available databases and software make LCA a key tool for integrated FEW nexus assessments.


  • Evaluation of virtual water and embodied energy, including virtual nutrients and animal feed.
  • Catchment-scale LCA of food based on diets and available LCA inventory databases.
  • Significant shares of embodied energy and virtual water in food found to be imported.
  • Water and energy hotspots highlight potential risks and trade-offs in food life cycle.
  • Currently available LCA databases offer potential for FEW nexus assessments.


ScienceDirect Website (PDF download)


21 February 2018


Resources, Conservation and Recycling. Volume 133, June 2018, Pages 320-330. DOI.

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