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Abstract

There is a growing momentum to analyse the broader interdependencies of the energy, water and food systems rather than evaluating them in isolation. For instance, it is impossible to consider a food system without evaluating its respective agriculture, water and energy characteristics using a suitable sustainability assessment methodology. The objective of this paper is to present the sustainability assessment model under development by the authors, which integrates the energy, water and food systems in one resource model. The integrated nexus tool is being designed to estimate the performance of the nexus at appropriate scale and resolution by identifying and quantifying the impact of given food production scenarios on terrestrial and marine eco-systems. Furthermore, the development of an integrated food system is key to the identification of the processes with the largest environment footprint. Life cycle assessment (LCA) is used to prepare detailed models of the sub-system components, determine the linkages between the different nexus constituents and evaluate impacts to the natural environment. The model developed considers the environmental impacts of selected processes within the food system with a special focus in regions of the world where water scarcity is a significant concern, such as Qatar. The nexus elements are described by sub-systems which are modelled using a combination of mass balance calculations, thermodynamic estimates and emission factors derived from literature and real plant data. The food sub-system includes the production and application of fertilizers and emissions from certain agriculture practices such as the raising of livestock. The water sub-systems include the production of water using desalination processes such as Reverse Osmosis and Multi-Stage flash and its distribution to the farm. The energy sub-systems consider both fossil fuel and renewable energy. Environmental emissions are calculated for a food production scenario in Qatar. This involves a crop production profile and corresponding land, water, energy and fertilizer requirements which will serve as inputs to the sub-system models. The outputs of the model are assigned into their respective LCA impact categories. Furthermore, desalination brine discharge is also considered for the aquatic-eco toxicity impact category. Within the sub-systems considered, it is shown the food sub-system produces the largest emissions, followed by fossil fuel powered desalination for irrigation. These emissions in addition the natural gas consumption can be significantly reduced if renewable energy in the form of PV systems are used, with however a significant land footprint. Furthermore, the available simulation tools, which consider the impact of desalination on the salinity of the wider Arabian Gulf, were critically evaluated with respect to their physical significance. When using the projection tool, it was found that Qatar’s food system contribution would represent approximately 0.5% of the total calculated salinity increase. However, evaluating historical data up to 2006, there has been no evidence to support significant differences in salinity conditions within the Arabian Gulf. As such, until a validated and comprehensive predicative model is developed, the models to date cannot provide conclusions on the salinity evolution of the Arabian Gulf and can only serve as comparisons between 2 scenarios.

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/content/papers/10.5339/qfarf.2013.EESP-018
2013-11-20
2020-02-27
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