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

ABSTRACTThe energy-water nexus, or the dependence of energy on water and water on energy, continues to receive attention as impacts on both energy and water supply and demand from growing populations and climate-related stresses are evaluated for future infrastructure planning. Changes in water and energy demand are related to changes in regional temperature, and precipitation extremes can affect water resources available for energy generation for those regional populations. Additionally, the vulnerabilities to the energy and water nexus are beyond the physical infrastructures themselves and extend into supporting and interdependent infrastructures. Evaluation of these vulnerabilities relies on the integration of the disparate and distributed data associated with each of the infrastructures, environments and populations served, and robust analytical methodologies of the data. A capability for the deployment of these methods on relevant data from multiple components on a single platform can provide actionable information for interested communities, not only for individual energy and water systems, but also for the system of systems that they comprise. Here, we survey the highest priority data needs and analytical methods for inclusion on such a platform.

The significance of the interconnection between water and energy, known as the water–energy (WE) nexus, is highly regarded in scientific publications. This study used a narrative review method to analyze the existing WE nexus studies performed before 2024 in 26 European countries. The aim of this study is to provide a comprehensive analysis of the existing WE nexus to identify research gaps and to report a conceptual overview of energy consumption related to groundwater use phases, ranging from the tapping to distribution. This information is valuable as a guideline for any future estimates in this field. The results indicate that the WE nexus in 26 European countries comprises a variety of topics, including the water supply system, wastewater treatment, hydropower, desalination, and biofuel production. Most of the focus has been on fossil fuel production, while water supply and desalination were considered rarely. Italy and Portugal had the largest WE nexus. It is highlighted that there have been no studies on the WE nexus focusing on the groundwater supply system that consider the conceptual hydrological model or hydrodynamic processes. In this work, a view of these aspects was provided by taking into account different hydrogeological and hydraulic scenarios that may affect the amount of energy required for groundwater exploitation. Most scientific publications have focused on quantitative analysis. In the future, it will be necessary for WE nexus models to place a greater emphasis on governance and the implications of the WE nexus approach.

Advancements in sustainable development of energy, water and environment systems

Sustainable Industrial Water and Energy Nexus Integration for an Industrial Park

The intricate interdependence of food, energy, and water (FEW) systems necessitates effective and coordinated educational efforts across various contexts to equip students with the skills to tackle FEW challenges. As an emerging interdisciplinary field, understanding educators’ and education researchers’ views on the FEW-Nexus perspective, self-efficacy, needs, and approaches to promoting community engagement are vital to facilitating the growth of this field. The National Collaborative for Research on Food, Energy, and Water Education (NC-FEW) is an NSF-funded, emergent, interdisciplinary community of educators and discipline-based education researchers engaged in sustained network and capacity building around FEW-Nexus. We present initial survey findings from 166 NC-FEW members, predominantly postsecondary faculty from varied disciplines. Our goal was to understand their views of FEW-Nexus perspective, self-efficacy in FEW-Nexus-specific teaching and education research, instructional design, and community engagement. The findings suggest that FEW-Nexus educators in the NC-FEW community view the Nexus as a blend of diverse concepts and themes, emphasizing the necessity of establishing a concrete definition of the nexus perspective. Their self-efficacy levels were higher in general STEM teaching (mean = 4.03) and STEM education research (mean = 3.61) compared to FEW-Nexus-specific teaching (mean = 3.43) and education research (mean = 3.18). Respondents reported feeling moderately connected to the FEW-Nexus educator community (mean = 2.21). They also outlined anticipated community benefits and contributions to promoting teaching and learning in the FEW-Nexus. These findings highlight the significance of boosting FEW-Nexus educators’ self-efficacy and building a stronger sense of community, having important implications for professional development in emerging fields and broader educational reform endeavors.

Urban energy–water nexus based on modified input–output analysis

Advances in integration of energy, water and environment systems towards climate neutrality for sustainable development

The growing global population and increase in demand for water, energy and food resources in the face of climate change-induced scarcity, presents the occurrence of interlinked food shortages, water scarcity, and insufficient energy resources as increasingly probable in the future. New ways of thinking and flexible forms of resource governance are urgently required to address these challenges. In particular, a greater understanding and consideration of interdependencies and interlinkages across water, energy and food policy domains is required. The contemporary approach of constructing water, energy, and food as a nexus has been strongly promoted as a global research agenda and emerging development paradigm. At the core of nexus thinking is the recognition that water, energy and food resources are interlinked in a web of complex interactions in which use and availability are interdependent. The way of thinking encouraged by the nexus reinvigorates the call for the adaptation of existing governance frameworks to better reflect and respond to intersectoral interdependencies such that trade-offs may be managed and synergies exploited. The assumption is that this will lead to better management of these resources, mitigating the negative impacts of water, energy and food insecurity. Increased scholarly and policy attention notwithstanding, the water, energy and food nexus is not a clearly defined construct, nor a tested and accepted framework. It remains an emerging agenda that encounters significant conceptual and practical challenges. This book investigates existing conceptualisations of the water, energy and food nexus, particularly in relation to its application to water, energy, and food policy domains, to identify its underlying utility. Based on a construction of the water, energy and food nexus as a lens through which intersectoral interdependencies can be considered and prioritised in decision-making, the investigation in this book advances to consider the implication of nexus thinking for law. In particular, this book investigates the factors requiring reflection within the law to enable vertical and horizontal coordination across the water, energy and food nexus. This entails positioning law within the broader institutional context shaping political decision-making across water, energy and food policy domains to understand what role the law plays in enabling and constraining coordination. Through organisational, doctrinal and empirical analyses of existing coordination processes in the case study site of Cape Town, South Africa, lessons are drawn from the successes and failures such that an understanding is constructed of the nature and content of an enabling regulatory environment. Recommendations are then made for those factors requiring reflection within the regulatory design to better support coordination across the water, energy and food nexus.

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.

The water–energy nexus in Middle East and North Africa

While the literature on the water-energy nexus tends to focus on scarcity and security, scientific research is revealing increasing concerns with the impact of energy production on water quality. This chapter explores the politics of energy and water quality, with a focus on water contamination associated with coal and shale gas development. It presents evidence of the effects of fossil fuel exploration and production on water quality, noting the life cycle water quality impacts of the coal industry and emerging work on the effects of unconventional shale gas and tight oil associated with hydraulic fracturing. While the science is drawn primarily from the United States, the chapter then considers the global implications of these findings for policy design. It argues that current regulatory approaches are mismatched with the environmental risks and calls instead for a holistic approach to policy design and management that brings together the energy and water sectors.

Since the Industrial Revolution, increased fossil use, land use changes, and deforestation have elevated atmospheric greenhouse gas concentrations well above historical levels. This has led to more frequent and intense climate events, including heatwaves, droughts, heavy rainfall, and floods worldwide. These changes place increasing pressure on the interconnected agriculture, water, and energy systems, threatening progress toward sustainability in natural resource management. Water is central to the agriculture-water-energy relationship, serving as a key input for both agriculture and energy. Disruptions in the hydrological cycle decrease water availability, quality, and distribution, directly affecting water-dependent sectors, especially agriculture. In Türkiye, agriculture uses about 77% of total freshwater withdrawals, making the country highly vulnerable to climate-driven water stress. Higher temperatures, longer droughts, and unpredictable rainfall reduce both agricultural output ad hydroelectric power, increasing risks to food and energy security. This study examines how extreme climate events affect the agriculture- water-energy nexus in Türkiye. It offers policy recommendations focused on data integration, institutional coordination, technological innovation, and legal improvements. The results show that integrated water management and nexus-based strategies will enhance Türkiye’s climate adaptation and support. Progress toward the United Nations Development Goals (SDGs 6, 7, 12, 13, and 15).

Reservoir-based hydropower systems represent key interactions between water and energy systems and are being transformed under policy initiatives driven by increasing water and energy demand, the desire to reduce environmental impacts, and interacting effects of climate change. Such policies are often guided by complex system models, whereby divergence in system representations can potentially translate to incompatible planning outcomes, thereby undermining any planning that may rely on them. We review different approaches and assumptions in hydropower representation in water and energy systems. While the models and issues are relevant globally, the review focuses on applications in California given its extensive development of energy and water models for policy planning, but discusses the extent to which these observations apply to other regions. Structurally, both water-driven and energy-driven management models are similar. However, in energy models, hydropower is often represented as a single-priority output. Water management models typically allocate water for competing priorities, which are generally uninformed by dynamic electricity load demand, and often result in a lower priority for hydropower. In water models, constraints are increasingly resolved for non-energy components (e.g. inflow hydrology and non-energy water demand); few analogues exist for energy models. These limitations may result in inadequate representations of each respective sector, and vastly different planning outcomes for the same facilities between the two different sectors. These divergent modeling approaches manifest themselves in California where poorly reconciled outcomes may affect decisions in hydropower licensing, electricity grid flexibility and decarbonization, and planning for environmental water. Fully integrated water-energy models are computationally intensive and specific to certain regions, but better representation of each domain in respective efforts would help reconcile divergences in planning and management efforts related to hydropower across energy and water systems.

In the next twenty years, the scarcity of food shortage and drinking water will appear in Egypt due to the growth of industries and agriculture. This paper develops a conceptual design of the new technologies in the field of water–energy–food in new cities. Border lines are the internal relationship, external influence, and linkage system evaluation for WEF nexus. The major problems of using fossil energy in desalination are emissions and non-renewability, as well as the preference for dispersed freshwater production instead of concentrated output. The design of a desalination system that is integrated with renewable energies is critical these days. This type of system can also reduce the production of environmental pollutants due to reduced energy consumption and transfer of freshwater. GIS data from the United Nations have confirmed the existence of an underground reservoir in Wadi-Dara that can cultivate 1000 acres using smart farming techniques to reach a circular economy for an integrated solution between the water–energy nexus. The possibility of cultivating a hundred acres in Wadi-Dara on the Red Sea coast exists, through which about one million people could be settled. In this comprehensive review, we conducted a deep study in order to establish a sustainable integrated lifestyle in the Dara Valley region in terms of the availability of potable water, clean energy, and agriculture. Sustainable integrated solutions were conducted for seawater desalination using beach sand filtration wells as a pretreatment for seawater using renewable energy, e.g., wind energy (18% wind turbines), and photovoltaic panels (77% PV panels). Strategic food will be cultivated using smart farming that includes an open ponds cultivation system of microalgal cells to synthesis (5.0% of bio-fuel (. Aqua agriculture and aquaponics will cultivate marine culture and integrate mangrove, a shrimp aquaculture. A municipal waste water treatment is conceived for the irrigation of shrubby forests and landscapes. Mixotrophic cultures were explored to achieve a sustained ecological balance. Food, poultry and animal waste management, as well as a cooker factory, were included in the overall design. The environmental impact assessment (EIA) study shows a low risk due to anticipated net zero emissions, a 75% green city, and optimal waste recycling. This research assists in combining research efforts to address the challenging processes in nexus research and build resilient and sustainable water, energy, and food systems.

Under global climate change and resource crisis, the correlation and restriction between energy, water, and carbon emission are increasingly prominent, which has posed great challenges for the sustainable development of energy systems. This article develops a dual-interval stage-fuzzy credibility-constrained programming model for regional energy system management problems with energy–water nexus (EWN) and carbon emission reduction, in which uncertainties expressed as discrete intervals, probability distributions, and dual-interval fuzzy numbers can be addressed. It can provide a trade-off among economic cost, system risk, and environmental objective. Then, the hybrid programming method is applied to a case of Guangdong Province, China to verify its applicability, where a series of scenarios with respect to water resources and carbon emission constraints are explored and examined. The robust solutions of optimal strategies for electricity generation, capacity expansion, water supply, and carbon capture are investigated and obtained. Results disclose that different scenarios associated with water resource availability and carbon emissions would deeply affect the EWN system planning: (1) Compared with low carbon emission standard, the proportion of renewable power generation under high carbon emission scenario would increase by [1.39, 1.68] %, [1.69, 2.35] %, and [1.49, 1.94] % in periods 1–3, respectively. (2) Scarce water availability scenario would restrict coal-fired power generation and simulate the development of renewable energy. These findings can be useful for decision makers to gain deep insights into energy system management in a sustainable way considering energy structure adjustment, multiple uncertainties, EWN, and carbon emission reduction.