A new paradigm for sustainable, integrated, water resources management is emerging from international conferences around the world. Its most succinct description is ‘the water–food–energy nexus for a green economy’. The water, food and energy nexus aims at the most efficient, best practice principles applied throughout the full food supply chain. This includes consideration of reducing wastage of the food for various reasons in the supply chain. This paper describes the global opportunities for better efficiency and resources conservation in the water, food, and energy supply chains with examples from Australia. Food wastage equates on average to 243 l day⁻¹ of water per person in the food they throw away, which is 1.5 times the daily water use per person in the UK. The concepts of virtual water and water footprint can help in identifying opportunities to save water by targeting reduction of wastage of food that has the highest virtual water content. A green economy aims at achieving optimised supply chain objectives in a manner that espouses the sustainability principle, gives due attention to environmental concerns and helps with eradication of poverty and hunger.

Virtual water or land use is the volume of water or area of land, respectively, used to produce a unit food commodity that is traded. Estimates of future virtual water or land use (as potential mechanisms for mitigating against food insecurity due to resource scarcity) are limited by the need for complex modelling and data requirements regarding trade, for which the data or expertise might be rare or unavailable. This paper presents a simple food balance approach for estimating the status quo food demand and supply and associated virtual water or land use transfers under future conditions. The method is spatially-scalable, accessible to a wider range of users, and illustrated using UK feed barley supply. Key features of the method are: ● Proportionate distribution of a target food item over utilization components is estimated from the FAO Food Balance Sheet of the country of analysis and used to distribute future supply over utilization components. ● The balance between demand and supply is used to estimate the direction and magnitude of virtual water or land use transfers. ● The method can be scaled up from national to regional and global levels and to cover multiple food items.

The water-energy-food (WEF) nexus concept highlights the importance of integrative solutions that secure resource supplies and meet demands sustainably. There is a need for translating the nexus concept into clear frameworks and tools that can be applied to decision making. A simulation and analytics framework, and a concomitant Nexus Simulation System (NexSym) is presented here. NexSym advances the state-of-the-art in nexus tools by explicit dynamic modelling of local techno-ecological interactions relevant to WEF operations. The modular tool integrates models for ecosystems, WEF production and consumption components and allows the user to build, simulate and analyse a “flowsheet” of a local system. This enables elucidation of critical interactions and gaining knowledge and understanding that supports innovative solutions by balancing resource supply and demand and increasing synergies between components, while maintaining ecosystems. NexSym allowed assessment of the synergistic design of a local nexus system in a UK eco-town. The design improved local nutrient balance and meets 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.

Society currently relies heavily on centralized production and large scale distribution infrastructures to meet growing demands for goods and services, which causes socioeconomic and environmental issues, particularly unsustainable resource supply. Considering local production systems as a more sustainable alternative, this paper presents an insight-based approach to the integrated design of local systems providing food, energy, and water to meet local demands. The approach offers a new hierarchical and iterative decision and analysis procedure incorporating design principles and ability to examine design decisions, in both synthesis of individual yet interconnected subsystems and integrated design of resource reuse across the entire system. The approach was applied to a case study on design of food-energy-water system for a locale in the U.K.; resulting in a design which significantly reduced resource consumption compared to importing goods from centralized production. The design process produced insights into the impact of one decision on other parts of the problem, either within or across different subsystems. The result was also compared to the mathematical programming approach for whole system optimization from previous work. It was demonstrated that the new approach could produce a comparable design while offering more valuable insights for decision makers.

Centralised production of essential products and services based on fossil fuels and large scale distribution infrastructures has contributed to a plethora of issues such as deterioration of ecosystems, social-economic injustice and depletion of resources. The establishment of local production systems that deliver various products for local consumption (e.g. food, energy and water) by making the best use of locally available renewable resources can potentially alleviate unsustainable resource consumption. The main objective of this work is to develop process systems engineering tools combined with the concept of resource accounting using exergy for the design of such local production systems. A general design framework comprising an optional preliminary design stage followed by a simultaneous design stage based on mathematical optimisation is proposed. The preliminary design stage considers each supply subsystem individually and allows insights into the potential interactions between them. The simultaneous design stage yields an optimal design of the local production system and has the capacity to include all design integration possibilities between the subsystems and generate a truly integrated design solution. The proposed methodology, which reflects generalised principles for designing local production systems, has been illustrated through a case study on the integrated design of the food-energy-water nexus for a designated eco-town in UK. It demonstrates the advantages of an integrated design of a system making use of local resources to meet its demands over a system relying on centralised supplies and a design without considering integration opportunities between subsystems.

The existence of a water-energy-food ‘nexus’ has been gaining significant attention in international natural resource policy debates in recent years. We argue the term ‘nexus’ can be currently seen as a buzzword: a term whose power derives from a combination of ambiguous meaning and strong normative resonance. We explore the ways in which the nexus terminology is emerging and being mobilised by different stakeholders in natural resource debates in the UK context. We suggest that in the UK the mobilisation of the nexus terminology can best be understood as symptomatic of broader global science-policy trends, including an increasing emphasis on integration as an ideal; an emphasis on technical solutions to environmental problems; achievement of efficiency gains and ‘win-wins’; and a preference for technocratic forms of environmental managerialism. We identify and critique an ‘integrative imaginary’ underpinning much of the UK discourse around the concept of the nexus, and argue that attending to questions of power is a crucial but often underplayed aspect of proposed integration. We argue that while current efforts to institutionalise the language of the nexus as a conceptual framework for research in the UK may provide a welcome opportunity for new forms of transdisciplinary, they may risk turning nexus into a ‘matter of fact’ where it should remain a ‘matter of concern’. In this vein, we indicate the importance of critique to the development of nexus research.

Recent advances in detailed multiregional input-output databases offers new opportunities to use these environmental accounting tools to explore the interrelationships between energy, water and food–the energy-water-food nexus. This paper takes the UK asa case study and calculates energy, water and food consumption-based accounts for 1997–2013. Policies, designed to reduce the environmental impact of consumption of products, can intervene at many stages in a product’s whole life-time from ‘cradle to gate’. We use input-output analysis techniques to investigate the interaction between the energy, water and food impacts of products at different points along their supply chains, from the extraction of material and burning of energy, to the point of final consumption. We identify the twenty most important final products whose large energy, water and food impacts could be captured by various demand-side strategies such as reducing food waste or dietary changes. We then use structural-path analysis to calculate the twenty most important supply chains whose impact could be captured by resource efficiency policies which act at the point of extraction and during the manufacturing process. Finally, we recognise that strategies that aim to reduce environmental impacts should not harm the socioeconomic well-being of the UK and her trade partners and suggest that pathways should be targeted where the employment and value added dependencies are relatively low.

The use of food quotients (FQ) calculated from dietary records is proposed for predicting respiratory quotients (RQ) that are needed for calculating free-living energy expenditure determined by the doubly-labeled water method which predicts respiratory CO2 production. This approach is based on the fact that, over the relatively long periods of double-isotope measurements (10-20 days), FQ (which can be obtained from a single 4-day measurement of dietary composition) must equal RQ in subjects in energy balance. It is shown that FQ can easily be adjusted to account for anabolism or catabolism for subjects not in energy balance. Typical RQ values are reported for various population sub-groups residing in the United Kingdom (omnivorous adults, vegetarians, vegans, Asian immigrants, and weaned and breast- and bottle-fed infants).(wz)

The nexus represents a multi-dimensional means of scientific enquiry which seeks to describe the complex and non-linear interactions between water, energy, food, with the climate, and further understand wider implications for society. These resources are fundamental for human life but are negatively affected by shocks such as climate change and characterize some of the main challenges for global sustainable development. Given the multidimensional and complex nature of the nexus, a transdisciplinary approach to knowledge development through co-production is needed to timely and effectively inform the decision making processes to build societal resilience to these shocks going beyond the sectorality of current research practice. The paper presents findings from five themed workshops (shocks and hazards, infrastructure, local economy, governance and governments, finance and insurance) with 80 stakeholders from academia, government and industry in the UK to explore the impact of climate and weather shocks across the energy-food-water nexus and barriers to related responses. The research identified key stakeholders’ concerns, opportunities and barriers to better inform decision making centred on four themes: communication and collaboration, decision making processes, social and cultural dimensions, and the nature of responses to nexus shocks. We discuss implications of these barriers and how addressing these can better facilitate constructive dialogue and more efficient decision-making in response to nexus shocks.

Large quantities of water are required to produce the food for a nation, some of which is derived within the country and some associated with imported food commodities. In this study, we consider the spatially explicit potential impact of alternative healthier eating scenarios for the UK on global blue water scarcity using the concept of a water scarcity footprint. The water required to produce the food consumed by the UK was estimated at 52.6Gm3/y of which 93% is from rainfall at the point where it falls and 7% is “blue” water withdrawn from surface and ground water resources. Five alternative healthier diets were considered and the impact on the blue water scarcity footprint was modest (ranging from −3% to +2% compared to baseline). However more significant impacts were projected on the geographical distribution of the blue water scarcity footprint. This study has shown that if current trade patterns continue, policies to promote healthier eating in the UK may contribute to increased blue water scarcity at home and in other parts of the world. The use of virtual water estimates and global datasets of water scarcity can help to understand the potential environmental impacts of alternative diets.