Food-energy-water nexus: A life cycle analysis on virtual water and embodied energy in food consumption in the Tamar catchment, UK

Gloria Salmoral,Xiaoyu Yan

doi:10.1016/j.resconrec.2018.01.018

Gloria Salmoral, Xiaoyu Yan

Open Access

https://doi.org/10.1016/j.resconrec.2018.01.018

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Abstract

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. Our 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%). Our 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.

Highlights

Food security in the UK relies significantly on production in other countries and food imports account for about 50% of the total food supply in terms of calorific value
This study shows the potential of Life cycle assessment (LCA) applications and ready available life cycle inventory (LCI) databases in FEW nexus studies from a food consumption perspective
Beef and milk show the largest appropriation of green water with 60% (146 hm3) and 14% (34 hm3), respectively, due to the role that pastures play on animal feed for ruminant livestock systems (Fig. 2 and Table A3 in the Supplemental material)

Summary

Introduction

Food security in the UK relies significantly on production in other countries and food imports account for about 50% of the total food supply in terms of calorific value (de Ruiter et al, 2015) This reliance is not limited to the food products, and applies to key inputs during the food life cycle. More recently a few studies have assessed the environmental implications of different diets and food consumption patterns (De Laurentiis et al, 2016; Nemecek et al, 2016). These LCA studies tend to focus on greenhouse gas (GHG) emissions

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