A Water and Energy Nexus

Engineering innovations—including those in heat and mass transfer—are needed to provide food, water, and power to a growing population (i.e., projected to be 9.8 × 109 by 2050) with limited resources. The interweaving of these resources is embodied in the food, energy, and water (FEW) nexus. This review paper focuses on heat and mass transfer applications which involve at least two aspects of the FEW nexus. Energy and water topics include energy extraction of natural gas hydrates and shale gas; power production (e.g., nuclear and solar); power plant cooling (e.g., wet, dry, and hybrid cooling); water desalination and purification; and building energy/water use, including heating, ventilation, air conditioning, and refrigeration technology. Subsequently, this review considers agricultural thermal fluids applications, such as the food and water nexus (e.g., evapotranspiration and evaporation) and the FEW nexus (e.g., greenhouses and food storage, including granaries and freezing/drying). As part of this review, over 100 review papers on thermal and fluid topics relevant to the FEW nexus were tabulated and over 350 research journal articles were discussed. Each section discusses previous research and highlights future opportunities regarding heat and mass transfer research. Several cross-cutting themes emerged from the literature and represent future directions for thermal fluids research: the need for fundamental, thermal fluids knowledge; scaling up from the laboratory to large-scale, integrated systems; increasing economic viability; and increasing efficiency when utilizing resources, especially using waste products.

“iZindaba Zokudla” means we talk about the food that we eat. iZindaba Zokudla is a public innovation lab that uses stakeholder-engagement methods to create “opportunities for urban agriculture in a sustainable food system.” iZindaba Zokudla is presented as an extra-institutional means to govern the water, land, energy, and waste nexus. This reflective essay critically describes iZindaba Zokudla and applies this to the design of institutional steering mechanisms to govern the food, water, land, and energy nexus towards sustainability. Governance is an intersubjective and interactive process between the subjects of governance and governance itself. Sustainability, as an interactive process, implies the creation of autocatalytic and symbiotic communities in society that integrates diverse actors and stakeholders, inclusive of scientific and lay actors, and ecosystems. iZindaba Zokudla is a means to govern and create such communities, and this article describes and reflects on how iZindaba Zokudla has created and managed such symbiotic communities or autocatalytic networks in the food system. The article generalises how the activities conducted in iZindaba Zokudla can be used to govern the water, land, energy, and waste nexus for sustainability. The article shows how iZindaba Zokudla has realised a progressive governance through the facilitation of its Farmers' Lab and website; how it has created opportunities for participation; and how it enables critical reflection in society.

Nexus research can help address issues arising at the intersection of traditionally independently treated management, policy, and research areas. While an extensive body of literature and reviews have been published on the water, food and energy nexus, biodiversity is less commonly featured in food and water nexus research, particularly in India. India hosts a large proportion of the world’s biological diversity. At the same time, it is facing one of the world's highest habitat conversion rates, among others for agricultural production, as well as increasing water scarcity. Hence, the integration of biodiversity considerations into food and water nexus management and governance decisions is particularly critical in India. Here, we explore linkages at the food, water and biodiversity (FWB) nexus in India using a systematic review of peer-reviewed literature. A total of 208 nexus linkages were extracted from 55 articles and mapped using a qualitative systems mapping approach. Results show a strong interdependence between all three nexus nodes, with biodiversity exhibiting the highest number of linkages across the system (137 linkages), followed by water (131 linkages) and food (120 linkages). Our results reflect the state-of-the-art of research on biodiversity at the food-water nexus in India and highlight the importance of better understanding the linkages and tradeoffs at India's FWB nexus.

Optimisation of the integrated water – energy systems: a review with a focus in Process Systems Engineering

Iran, situated in the Middle East, is recognized as a prominent energy hub, with its economy heavily reliant on the exportation of energy. Iran currently faces significant water stress, underscoring the importance of examining its Water–Energy (WE) nexus. Hence, it is crucial to examine the Water–Energy (WE) nexus in this nation. This study evaluates Iran’s WE nexus from upstream to downstream in its energy subsystem (2007–2017) through an integrated framework combining water footprint analysis, water consumption methodologies, and nexus system modeling. This study assessed the WE nexus from upstream to downstream in Iran from 2007 to 2017. Key findings reveal that steam turbine power plants, particularly Ramin and Neka, exhibit the highest water consumption intensities, approximately 2.04 and 2.65 m3/MWh respectively, making them critical targets for efficiency improvements or retirement. Conversely, combined-cycle plants with dry cooling technology show significantly lower water intensity (0.18 m3/MWh), presenting viable alternatives. The study recommends shifting energy infrastructure towards combined-cycle and gas turbine plants to mitigate water stress, thus providing actionable insights for sustainable energy and water resource management in water-stressed regions.

The growing demand for water in domestic, agricultural, and energy production applications poses a significant challenge for Jordan. This work assesses the role of brackish water desalination as an alternative to alleviate water scarcity in semi-arid regions. Desalination is still limited in its application in Jordan due to high electricity tariffs. Shifting to renewable sources such as solar energy, abundant in the country, is a feasible way to power technologies with a high energy demand. In this work, we study the brackish water desalination plant at the Hashemite University in Jordan that is powered by a photovoltaic (PV) solar system (the HU PV-BWRO). The plant’s performance was evaluated in the context of the water-energy nexus as a hybrid water supply solution. While this work integrates essential elements, such as water availability, technical options, economic viability, and agricultural management, the analysis primarily focuses on the technical and economic aspects related to water, energy, and food. Water assessment results indicate that the groundwater wells near the HU campus are at risk of quality degradation over time, as they have shown a slight increasing trend in salinization from 2015 to 2023. Energy assessment results show a promising performance from the HU PV-BWRO desalination plant, with a specific energy consumption (SEC) value of 1.2 kWh m−3 (140% to 400% less energy consumption compared with other Jordanian desalination plants of similar capacity). Unit price comparisons indicate that the energy cost of PV (0.042 USD/m3) is 5 times less than the cost of grid electricity (0.24 USD/m3). The operational cost of the solar desalination plant at full capacity, is USD 0.23/m3. This is about 260% less than the operation cost for local, grid-powered desalination plants. Finally, it is estimated that by operating the plant at 50% of its total capacity, the produced water could be sufficient to irrigate up to 80% of the HU campus to increase agricultural production. This study highlights the importance of decreasing reliance on energy for water and food production, and it shows that the use of solar powered desalination could be used as an example in semi-arid regions, particularly in terms of integrating renewable energy and energy efficiency.

Water is needed to generate energy. Energy is required to deliver, clean, and evaporate water. There are extensive linkages between water and energy. Meanwhile, both resources may limit the other, especially in the context of urbanization and industrialization as well as climate change. Due to the large population and fast-growing economy, China is one of the most water and energy shortage countries in the world. Relations between water and energy are particularly strained. Unfortunately, up to now, little attention has been paid to the tension relation between water and energy in China. Studying water and energy nexus can provide more information than investigating them separately because of their concomitant relationship. In this paper, we reviewed the recent situations on these issues in China, mainly focused on the following topics: 1) energy consumption in water industry; 2) water consumption and energy nexus in energy industry and urban; 3) water and energy nexus in agriculture; and 4) Energy consumption by evapotranspiration and its cooling effect on reducing urban temperature. Extensive data are analyzed and reported in this study, which will be useful for policy making by taking account of climate change, urbanization, and population growth.

Powering an island system by renewable energy—A feasibility analysis in the Maldives

The water and energy nexus approach is a complex subject that involves diverse sectors and stakeholders, as well as temporal and spatial scales that are also diverse. When analyzing local or regional contexts, the approach may acquire specific interfaces. This article deals with the nexus of water and energy from the point of view of energy planning, inserting the context of climate change, and the dilemmas experienced in Brazil, related to the theme. It intends to bring to light such relations, for a reflection on the complexity of this narrative and the necessary arrangements for governance in this context. In the Brazilian case, the water and energy nexus is established primarily, since the electricity is mostly supplied by hydroelectric plants. As discussed in the paper, the expansion of hydroelectric plants in Brazil is reaching a limit, which will lead to the development of lower cost techniques in civil engineering and associated works, especially in arrangements of lower impact and greater efficiency. The climatic question also becomes relevant when analyzing the expansion of the electric system based on hydroelectricity, since this modal would be one of the most affected by climate changes, according to official projections. Therefore, knowledge of the water and energy nexus needs to be expanded in more detailed aspects, including edge and feedback effects, in addition to the incorporation of other relationships, and a systemic and integrative approach involving water and energy is needed to deal with issues associated with multiple uses and interdependencies.

Synergistic Tandem Solar Electricity-Water Generators

The key actions to advance knowledge about sustainable and resilient urban governance are identifying and analyzing innovative initiatives for managing the food, water, and energy nexus (FWEN) in cities. Rapid urban changes in the world’s cities are placing unprecedented demands on energy, water, food, and other systems, as each of them offers multiple life-supporting services. Identifying intersections across a diverse set of social actors and institutions represents a relevant agenda that can influence priority outcomes to urban communities, city regions, and their supporting ecosystems. It can be seen as a relevant strategy to advance toward a more integrated territorial planning in cities to strengthen actions to promote sustainable use of natural resources. These drivers have the potential to foster collaborative, functional, and transformative responses in the contexts of an institutional interplay, aiming to encourage co-management, bridging organizations, and social entrepreneurship among other stakeholders. From this background research, the chapter then presents the cases of the Brazilian cities of São José dos Campos and Florianópolis within the context of the “IFWEN – Understanding Innovative Initiatives for Governing Food, Water and Energy Nexus in Cities” project – as a basis to discuss this integrated perspective. The cases of São José dos Campos and Florianópolis illustrate, respectively, how actions on the FWEN for environmental protection and organic food production can contribute to the debate regarding innovation in urban governance and potential nexus enhancement. Due to the need to keep improving municipal planning, governance, and implementation of effective measures, a discussion is conducted regarding the potential of Local Climate Action Plans to increase the integration among sectors and actors. These insights arise from the cases of Recife and Fortaleza and their experience to tackle climate change and indicate that it might be possible to also foster the FWEN and enhance integrated governance at the municipal level. Moreover, this chapter also addresses insights from the cities of Recife and Fortaleza in Brazil regarding climate change adaptation and mitigation, focusing on their Local Climate Action Plan update under the “Urban-LEDS Phase II” project. These plans might be a strategic tool to foster FWEN and more integrated governance.KeywordsLocal Climate Action PlansIntegrated governanceAdaptationMitigationFWEN

The water, food and energy nexus is a critical component for sustainable development as global population and industrialization escalate. Agriculture is responsible for the majority of freshwater consumption worldwide, while one quarter of the world's energy is spent on food production and consumption. The connections between such vital areas necessitates a profound and integrated approach to securing the water, food and energy sectors across the world. Such an integrated approach should be based upon understanding the nexus between the three individual sectors, and on coordinating the interactions between them. As the global population is expected to reach 8 billion (8 × 109) by 2030, demands for essential services and higher living standards are becoming prevalent, and the need for conscious protection of vital resources – without which, meeting those demands and desires would be impossible – is more palpable than ever. Considering the impact of water and environmental crises on food and energy security, the integrated management of water, food and energy with the collaboration of all stakeholders could result in a significant check on any detrimental changes. Due to the critical importance of food, water and energy security, policies should be implemented to conserve and protect these essential resources. Therefore, it is very important to understand the logic governing this issue, and, in this chapter, definitions and logical approaches that govern the concept of the water, food and energy nexus, the potential crises ahead, and the effective management solutions, tools, and methods used in this field are all discussed, using case studies and examples.

Water, food, energy, and quality of life go hand in hand. The food we eat, the house we live in, the transports we use, and the things we cannot do without 24/7/365 determine our quality of life and require sustainable and steady supplies of water, food, and energy. Exponential growth in population and the fundamental right to have basic food and standards of living require increasing amounts of water and energy. The quantity of available freshwater and energy sources that directly affect the cost of production (irrigation and energy) and the transportation (energy) of food are diminishing. In addition, there is increased water pollution due to industrial uses of water. The direct use of such water for human consumption as well as irrigation for food production is prohibitive and requires technological solutions. Securing sustainable water, food, and energy supplies are more important challenges today for scientists and engineers than ever before. With the above in mind, Professors Mujtaba and Elbashir organized workshops in Qatar and in India in 2015. The Qatar workshop was on energy and water security and was coordinated by Professors Mujtaba and Elbashir and funded by the British Council (UK) and Texas A&M University (USA). Thirteen participants from the UK and 15 from Qatar (academics and industrialists) presented stimulating and state-of-the-art research and knowledge transfer ideas in energy and water over 3 days. The Indian workshop was on water, food, and energy nexus and was coordinated by professors Mujtaba and Srinivasan and funded by the Royal Society (UK) and the Department of Science and Technology (India). Three participants from the UK and 15 from India (academics and industrialists) presented stimulating and state-of-the-art research and knowledge transfer ideas in water, food, and energy over 3 days. A total of 40 presentations were made and both events received a great deal of national press coverage. The developments in energy-efficient water production, management, wastewater treatment, and energy-efficient processes for food and essential commodities were widely discussed at these workshops. This book presents those technical discussions for wider public benefit around the globe. The book has 37 contributions (most from the two workshops mentioned earlier) and is divided into four sections: • Section I: Water • Section II: Food • Section III: Energy • Section IV: Sustainable Future Section I includes 10 contributions on water desalination, water management, and wastewater treatment. Water desalination covers the state of the art in mode-based research in desalination together with the global water–energy challenge in desalination and forward osmosis-based desalination for agricultural irrigation. Water management covers topics on sustainable water management in industrial cities, water network synthesis, and water quality monitoring. Wastewater treatment includes four contributions on the removal of endocrine, water conservation, life cycle assessment into the synthesis of wastewater treatment plants, and appropriate technologies for supplying safe drinking water. Section II includes five contributions on food. The contributions cover advances in cereal processing, clean technology for sustainable food security, bioenergy in food production, water and energy consumption in food processing, and a mathematical model for food cooking undergoing phase changes. Section III includes 16 contributions on fossil fuel, biofuel, synthetic fuel, and renewable energy, and carbon capture. Fossil fuel includes two contributions on energy-efficient crude oil transport and the process industry economics of crude oil and petroleum derivatives. Biofuel has two contributions: biodiesel production from renewable sources and synthesis of biodiesel from used cooking oil. Synthetic fuel and renewable energy includes five contributions on gas-to-liquid (GTL)-derived synthetic fuel, the role of alternative aviation fuel, a modeling approach for the GTL Fischer–Tropsch reactor and carbon footprint, a distributed renewable energy system and management, and demand for and generation of a smart grid. Carbon capture contains seven contributions on the rotating packed bed for carbon capture, integration of natural gas combined cycle power generation and chemical absorption based carbon capture, postcombustion carbon capture, integration of supercritical coal-fired power plant and carbon capture, experimental and theoretical modeling of carbon capture and sequestration chain, and the performance of organic polymers for carbon capture. Section IV includes six contributions on a sustainable future. The topics cover the role of molecular thermodynamics in developing processes and products for a sustainable future, green engineering in process systems, the fundamental aspect of petrochemical water splitting, petrochemical approaches to solar hydrogen generation, a design and operation strategy of energy-efficient process, and the sustainability of process, supply chain, and enterprise.

The demand for water, food and energy is steadily increasing with growth expected at 30–50 percent in the next two decades (World Economic Forum, Water Security, The Water, Energy, Food and Climate Change Nexus, 2011). Balancing the elements of the water, energy and food nexus with climate change and its impacts on the availability of water for drinking, food production and changes in energy consumption is complex and challenging (Thirlwell et al., Energy–Water Nexus: Energy Use in the Municipal, Industrial, and Agricultural Water Sectors. Developed for the Canada–U.S. Water Conference, Washington DC, October 2, 2007; Waughray (ed.), Water security: The Water–Food–Energy–Climate Nexus, 2011; Bazilian et al., Energy Policy 39(12):7896–7906, 2012; Van Vuuren et al., Curr Opin Environ Sustain 4:18–34, 2012). Economic interests often favor short-term responses in production and consumption but, in turn, undermine long-term sustainability. Understanding the interconnections between water, energy and food using an ecosystem service approach offers a system-wide framework to achieve sustainable water, energy and food security given scarce resources. Natural capital accounting (NCA) integrates ecosystem services offering a means to identify, quantify and value ecosystem services (in monetary and non-monetary terms), leading to better decision-making for managing, preserving and restoring the natural environment (Voora and Venema, The Natural Capital Approach: A Concept Paper. International Institute for Sustainable Development, 2008). The United Nations (UN) System of Environmental-Economic Accounting for water is one example of translating biophysical water-related data into economic terms to improve decision outcomes for water. Energy reliability is closely linked to ecosystems given natural resource dependencies on the supply side and environmental degradation on the demand side. NCA encourages resiliency in energy systems using an integrated approach of environmental, economic, technical and social aspects. Given current and future demands, agricultural development requires a whole system approach. NCA is one tool that helps to bring together an integrated ecosystem perspective to agriculture. Developing robust systems of natural capital accounting in order to determine the contribution of ecosystem services to the water, energy and food nexus, and ultimately human well-being, is important if we are to realize the stated goals and targets of the UN’s Agenda 2030.

Environmental innovation and the food, energy and water nexus in the food service industry