Why do we need to model the interactions between energy, water, and food?
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Modelling the interactions between energy, water and food is important because the three resources are interdependent, and changes in one sector, as a result of policies, climate change or growing demands, can have serious implications for the others.
These concerns become more critical as populations grow and regions develop, with corresponding increases in consumption and pollution. Energy systems need water throughout their lifecycles, during raw material extraction, power plant cooling, hydropower generation and biofuel irrigation, for example. Water systems use energy for extracting and pumping source water, for desalination, for water purification and for the delivery and distribution of water. The food sector uses both energy and water extensively for irrigation, harvesting, distribution, processing, packaging and storage. The next few decades will see the global population reach 9 billion, with estimates showing up to 30% increases in the water, energy and food sectors globally, and much higher increases in emerging economies like Brazil and India. In addition, climate change will reduce the availability of water in many regions, including hydroelectricity. As these resources become more stressed, the interdependencies between the sectors become more critical, as does the need to model and understand these interdependencies.
'The next few decades will see the global population reach 9 billion, with estimates showing up to 30% increases in the water, energy and food sectors globally'
What kind of question can be answered by these models?
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With concerns increasing about these nexus issues, several modelling efforts have been initiated, accounting for different levels of interdisciplinary linkage across a range of spatial and temporal scales. Such models bring additional insights into the implications of policies in one sector on the others. For example, a nexus model can help compare differences in water demands when considering new energy capacity technology investments in, say, a gasworks, nuclear plant or wind farm. At the same time, a nexus model would be able to explore solutions for providing additional water by different means, such as desalination instead of transferring water via pipelines. Each of these water investments would have their own corresponding impacts on the energy system, and therefore on carbon emissions. The implications of various irrigation methods or crop choices on energy and water systems can also be analysed. Nexus models thus provide a holistic analysis by capturing inter-sectoral dynamics in policies, subsidies, changing climates and socio-economic pathways across the water-energy-food sectors.
The issue of adapting to climate change showcases the power of these models very well. Climate change will affect water availability, energy supply and demand, and food production. Addressing the three sectors together will allow us to adapt better, and more efficiently.
How can model-based results pave the way for understanding future energy and water demands?
Nexus analysis provides additional information which might otherwise be overlooked when considering future demands. For example, studies have shown that energy efficiency improvements in certain regions can decrease water demands by up to 15%. And electricity subsidies for farmers have a direct impact on over-pumping of groundwater as seen in some regions in India. The choice of a technology mix to meet future demands in one sector has a direct impact on the other sectors, and these dynamics
'Studies have shown that energy efficiency improvements in certain regions can decrease water demands by up to 15%'
are captured by nexus models. Thus, future energy, water or agricultural expansion plans can be combined in nexus models to get a complete picture of the implications and trade-offs, for example when considering coal, gas or renewables in the energy sector; desalination or re-use expansion in the water sector; increasing irrigation efficiency; or replacement of certain water-intensive crops.
How can these models help us to make more energy/water-conscious decisions?
Traditionally, decisions in the water, energy and food sectors are to a large extent made independently by sector-specific agencies or ministries, seldom communicating or sharing data and information with each other. This is partly because of the complexity of each of these systems, and the differences in the physical, spatial and temporal characteristics of each. Nexus models are not meant to replace the more detailed sector-specific methodologies, but should ideally serve as an additional layer, bringing together insights from the individual sector models, harmonising differences, identifying synergies and highlighting potential conflicts. Thus, a nexus framework promotes a more holistic analysis of traditional problems. For example, in a country like Pakistan, which is considering exploiting its previously untapped coal reserves (one of the largest in the world) to address growing energy concerns, a nexus approach would serve well to highlight the water implications of such a large scale strategy in an already severely water-stressed region. Similar decisions in other sectors, such as expanding irrigation systems, investing in desalination or growing biofuelcrops, would all benefit from the holistic perspective offered by a nexus framework.
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