The global water supply–demand gap is rising with population growth, urbanization trends, and industrialization. This situation is expected to push 40% of the world’s population below the water scarcity level by 2050. As of 2023, 20,000 desalination plants converting more than 40 bm3 of water annually in 150 countries. However, the energy-intensive operation, high desalination cost, and environmental footprint of conventional desalination systems require a technological breakthrough in the field to sustainably cope with the demand. This study presents a comprehensive and innovative approach to hybridizing two established desalination technologies for higher energy efficiency, higher water productivity, lower cost, and improved environmental operation. The proposed system is a hybrid multieffect desalination (MED) with an adsorption cycle (ad). The advantages of the proposed system include low-temperature operation (below ambient), double water production over the same top brine temperature, and high thermodynamic efficiency. A pilot-scale MEDAD with a water production capacity of 10 m3/day has been developed and tested. The study showed that the hybridization of the AD cycle with the conventional MED system decreased the bottom brine temperature to approximately 20 °C compared to 40 °C of the conventional MED system. Meanwhile, the productivity of hybrid systems surged to 2–3 times that of the conventional system. Moreover, the system operates at approximately 20% of the thermodynamic limit, which is the highest for any desalination system hitherto. Therefore, the system can be scaled up for any higher productivity as the most viable solution to desalinate seawater.
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An Innovative Approach to Hybridizing Two Established Desalination Technologies or Toward Ensuring a Future Global Water Supply: Using a Hybrid Multieffect Desalination with an Adsorption Cycle
Muhammad Wakil Shahzad and Muhammad Ahmad
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Water Governance in the Netherlands
M.L. (Marie Louise) Blankesteijn and W.D. (Wieke) Pot
Dutch water governance is world famous. It to a large extent determines the global public image of the Netherlands, with its windmills, polders, dikes and dams, and the eternal fight against the water, symbolized by the engineering marvel of the Delta Works. Dutch water governance has a history that dates back to the 11th century. Since the last 200 years, water governance has, however, undergone significant changes. Important historical events setting in motion longer-term developments for Dutch water governance were the Napoleonic rule, land reclamation projects, the Big Flood of 1953, the Afsluitdijk, the impoldering of the former Southern Sea, the ecological turn in water management, and the more integrated approach of “living with water.” In the current anthropocentric age, climate change presents a key challenge for Dutch water governance, as a country that for a large part is situated below sea level and is prone to flooding.
The existing Dutch water governance system is multilevel, publicly financed, and, compared to many other countries, still relatively decentralized. The responsibilities for water management are shared among the national government and Directorate-General for Public Works and Water Management, provinces, regional water authorities, and municipalities. Besides these governmental layers, the Delta Commissioner is specifically designed to stimulate a forward-looking view when it comes to water management and climate change. With the Delta Commissioner and Delta Program, the Netherlands aims to become a climate-resilient and water-robust country in 2050.
Robustness, adaptation, coordination, integration, and democratization are key ingredients of a future-proof water governance arrangement that can support a climate-resilient Dutch delta. In recent years, the Netherlands already has been confronted with many climate extremes and will need to transform its water management system to better cope with floods but even more so to deal with droughts and sea-levels rising. The latest reports of the Intergovernmental Panel for Climate Change show that more adaptive measures are needed. Such measures also require a stronger coordination between governmental levels, sectors, policies, and infrastructure investments. Furthermore, preparing for the future also requires engagement and integration with other challenges, such as the energy transition, nature conservation, and circular economy. To contribute to sustainability goals related to the energy transition and circular economy, barriers for technical innovation and changes to institutionalized responsibilities will need to be further analyzed and lifted.
To govern for the longer term, current democratic institutions may not always be up to the task. Experiments with deliberative forms of democracy and novel ideas to safeguard the interests of future generations are to be further tested and researched to discover their potential for securing a more long-term oriented and integrated approach in water governance.
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Puzzles of Commitment, Compliance, and Defection in Water Resource Management
John Waterbury
Collective action problems (CAPs) are ubiquitous in human undertakings including in the development and management of shared water resources. Various rational-actor models have been applied to understand their dynamics. These analyses tend to come to pessimistic conclusions based on the assumption of “free-riding” whereby any participant in a collective action (CA) will be motivated to benefit from the action without contributing to its costs. If all participants follow this logic, there will be no CA and hence no net benefit to the participants.
This view assumes the logic of individual rationality. It does not adequately account for observed behavior, which may be driven by collective or group rationality. CA in water management and other domains has been initiated and sustained despite the temptation of free-riding. To understand why, it is necessary to analyze the dynamics of commitment, i.e., the initial collective undertaking; compliance, i.e., sustaining the initial commitment; and defection, when compliance breaks down. None of these variables is static. With respect to water, the technological means of its management constantly change so that the dynamics of compliance change as well. Technological change must be anticipated in the commitment phase. Just as important, cost/benefit analysis must encompass assessing payoffs in domains not related to water itself. These payoffs may not be part of the formal terms of commitment but must inform the compliance process. When the process unravels, “water wars” may result although that has been a rare outcome.
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The Allocation of Groundwater: From Superstition to Science
Burke W. Griggs
Groundwater is a critical natural resource, but the law has always struggled with it. During the 19th and early 20th centuries, the common law developed several doctrines to allocate groundwater among competing users. The groundwater revolution of the mid-20th century produced an explosive growth in pumping worldwide—and quickly exposed the flaws of these doctrines. Legal rules predicated on land and on surface waters could not meet the challenges posed by the common-pool groundwater resource: those of understanding groundwater dynamics, quantifying the impacts of pumping on other water rights, and devising satisfactory remedies. Unfettered by received property restraints, pumping on an industrial, aquifer-wide scale depleted and contaminated aquifers, regardless of doctrine.
The groundwater revolution motivated significant legal developments. Starting in the 1970s, the Supreme Court of the United States adapted its methods for resolving interstate water disputes to include the effects of groundwater pumping. This jurisprudence has fundamentally influenced international groundwater law, including the negotiation of trans-boundary aquifer agreements. Advances in hydrogeology and computer groundwater modeling have enabled states and parties to evaluate the effects of basin-wide pumping. Nonetheless, difficult legal and governance problems remain. Which level of government—local, state, or national—should exercise jurisdiction over groundwater? What level of pumping qualifies as “safe yield,” especially when the aquifer is overdrawn? How do the demands of modern environmental law and the public trust doctrine affect groundwater rights? How can governments satisfy long-neglected claims to water justice made by Indigenous and minority communities? Innovations in groundwater management provide promising answers. The conjunctive management of surface and groundwater can stabilize water supplies, improve water quality, and protect ecosystems. Integrated water resources management seeks to holistically manage groundwater to achieve social and economic equity. Water markets can reward water conservation, attract new market participants, and encourage the migration of groundwater allocations to more valuable uses, including environmental uses.
The modern law of groundwater allocation combines older property doctrines with 21st-century regulatory ideals, but the mixture can be unstable. In nations with long-established water codes such as the United States, common-law Anglophone nations, and various European nations, groundwater law has evolved, if haltingly, to incorporate permitting systems, environmental regulation, and water markets. Elsewhere, the challenges are extreme. Long-standing calls for groundwater reform in India remain unheeded as tens of millions of unregulated tube wells pump away. In China, chronic groundwater mismanagement and aquifer contamination belie the roseate claims of national water law. Sub-Saharan nations have enacted progressive groundwater laws, but poverty, racism, and corruption have maintained grim groundwater realities. Across the field, experts have long identified the central problems and reached a rough consensus about the most effective solutions; there is also a common commitment to secure environmental justice and protect groundwater-dependent ecosystems. The most pressing legal work thus requires building practical pathways to reach these solutions and, most importantly, to connect the public with the groundwater on which it increasingly depends.
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Environmental Policy and the Double Dividend Hypothesis
Antonio M. Bento
Since the 1990s, the so-called double-dividend debate—that is, the possibility that swaps of newly environmental taxes for existing distortionary taxes such as taxes on labor or capital could simultaneously improve environmental quality and reduce the distortionary costs of tax system—has attracted the attention of policymakers and academics. And while prior to the 1990s environmental economics as a field was not ready to inform this debate, scholars quickly moved to incorporate insights of the theory of second-best from public economics to inform the discussion. The result was a substantial advancement of the field of environmental economics, with the evaluation of the welfare effects of alternative policy instruments relying on general equilibrium models with pre-existing distortions.
Initially, scholars casted substantially doubt on the prospects of a double dividend, and suggested that environmental tax reforms would not reduce the distortionary costs of the tax system. This is because studies documented that the tax-interaction effect dominated the revenue-recycling effect. That is, newly environmental taxes interact with pre-existing distortions in labor markets. And even when the revenues of environmental taxes are used to cut the rate of the labor tax, the environmental tax reform exacerbates, rather than alleviate, pre-existing distortions in labor markets. Throughout the 2000s and in more recent decades, the literature has documented many instances where a double dividend is more likely to exist, including in the context of developing countries.
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Review of Rain and Atmospheric Water Harvesting History and Technology
Nathan Ortiz and Sameer Rao
Water is an essential resource and is under increased strain year after year. Fresh water can be a difficult resource to come by, but the solution may lie in the invisible water source that surrounds us. The atmosphere contains 12.9 trillion m3 of fresh water in liquid and vapor forms. Rain and fog harvesting were the first solutions developed in ancient times, taking advantage of water that already existed in a liquid state. These technologies do not require energy input to overcome the enthalpy of condensation and thus are passive in nature. They are, however, limited to climates and regions that experience regular rainfall or 100% relative humidity (RH) for rainwater and fog harvesting, respectively. People living in areas outside of the usable range needed to look deeper for a solution. With the advent of refrigeration in the 20th century, techniques came that enabled access to the more elusive water vapor (i.e., <100% RH) that exists in the atmosphere. Refrigeration based dewing (RBD) is the most common technique of collecting water vapor from the atmosphere and was first developed in the 1930s but found greater adoption in the 1980s. RBD is the process of cooling ambient air to the dew point temperature. At this temperature water vapor in the atmosphere will begin to condense, forming liquid droplets. As the humidity ratio, or amount of water in a given quantity of air (gwater/kgdry-air) continues to decrease, RBD becomes infeasible. Below a threshold of about 3.5 gwater/kgdry-air the dewpoint temperature is below the freezing point and ice is formed during condensation in place of liquid water. Since the turn of the century, many researchers have made significant progress in developing a new wave of water harvesters capable of operating in much more arid climates than previously accessible with RBD. At lower humidity ratios more effort must be expended to produce the same amount of liquid water. Membrane and sorbent-based systems can be designed as passive or active; both aim to gather a high concentration of water vapor from the ambient, creating local regions of increased relative humidity. Sorbent-based systems utilize the intrinsic hydrophilicity of solid and liquid desiccants to capture and store water vapor from the atmosphere in either their pore structure (adsorbents) or in solution (absorbents). Membrane separators utilize a semipermeable membrane that allows water vapor to pass through but blocks the free passage of air, creating a region of much higher relative humidity than the environment. Technologies that concentrate water vapor must utilize an additional condensation step to produce liquid water. The advantage gained by these advancements is their ability to provide access to clean water for even the most arid climates around the globe, where the need for secure water is the greatest. Increased demand for water has led scientists and engineers to develop novel materials and climb the energy ladder, overcoming the energy requirements of atmospheric water harvesting. Many research groups around the world are working quickly to develop new technologies and more efficient water harvesters.
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A Review of Alternative Water Supply Systems in ASEAN
Cecilia Tortajada, Kris Hartley, Corinne Ong, and Ojasvee Arora
Climate change, water scarcity and pollution, and growing water demand across all sectors are stressing existing water supply systems, highlighting the need for alternative water supply (AWS) systems. AWS systems are those that have not typically existed in the traditional supply portfolio of a given service area but may be used to reduce the pressure on traditional water resources and potentially improve the system’s resilience. AWS systems have been used for decades, often where traditional systems are unable to maintain sufficient quantity and quality of water supply. Simpler forms of AWS systems, like rainwater harvesting, have been used for centuries. As human population and water demand have increased, AWS systems now play a larger role in the broader supply portfolio, but these systems alone are not able to fully resolve the increasingly complex mix of problems contributing to water stress. Entrenched challenges that go beyond technical issues include low institutional capacity for developing, operating, and maintaining AWS systems; monitoring water quality; more efficiently using available resources; and establishing clear responsibilities among governments, service providers, and property owners. Like traditional water supply systems, AWS systems should be developed within a sustainability-focused framework that incorporates scenario planning to account for evolving natural and institutional conditions. In ASEAN, the adoption of AWS systems varies among countries and provides context-specific lessons for water management around the world. This article provides an overview of AWS systems in the region, including rainwater harvesting, graywater recycling, wastewater reclamation, desalination, and stormwater harvesting.
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Ceremonial and Subsistence Water Use
Dale Whittington and Michael Hanemann
Water for cultural and religious purposes, referred to as ceremonial and subsistence (C&S) use, is a distinctive feature of many Indigenous and other communities. Whether this constitutes a legitimate claim for water for an American Indian Tribe in the United States was litigated in the context of a trial to determine the federal government’s obligation to reserve water for Indian Tribes whom it had settled on reservations during the 19th century. Following a U.S. Supreme Court ruling in 1963, the amount of water the federal government was obligated to provide was defined as the quantity of water that could be used to grow crops profitably on the reservation. In 2001, the Arizona Supreme Court adopted a new definition, for Arizona, namely the amount of water that ensured the reservation would be a permanent homeland. However, parts of this 2001 ruling were contradictory and seemed to support the profitable irrigation standard. What the Arizona Supreme Court actually meant was not put to the test until the Hopi water rights trial in 2020. The Hopi Tribe’s water rights claims included a claim for new water to replace diminishing local water supplies in order for the Tribe to continue cultivating traditional varietals of corn and other crops. Hopi agricultural practices date back at least a millennium and are a central part of Hopi culture and religion. The crops are used in cultural and religious ceremonies and are not sold commercially. The Hopi claim for water for irrigation to support C&S cultivation was opposed by the other parties to the case and was rejected by the court.
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Ecological Water Management in Cities
Timothy Beatley
Managing water in cities presents a series of intersecting challenges. Rapid urbanization, wasteful consumption, minimal efforts at urban or ecological planning, and especially climate change have made management of urban water more difficult. Urban water management is multifaceted and interconnected: cities must at once address problems of too much water (i.e., more frequent and extreme weather events, increased riverine and coastal flooding, and rising sea levels), but also not enough water (e.g., drought and water scarcity), as well as the need to protect the quality of water and water bodies.
This article presents a comprehensive and holistic picture of water planning challenges facing cities, and the historical approaches and newer methods embraced by cities with special attention to the need to consider the special effects of climate change on these multiple aspects of water and the role of ecological planning and design in responding to them. Ecological planning represents the best and most effective approach to urban water management, and ecological planning approaches hold the most promise for achieving the best overall outcomes in cities when taking into account multiple benefits (e.g., minimizing natural hazards, securing a sustainable water supply) as well as the need to protect and restore the natural environment. There are many opportunities to build on to the history of ecological planning, and ecological planning for water is growing in importance and momentum. Ecological planning for water provides the chance to profoundly rethink and readjust mankind’s relationship to water and provides the chance also to reimagine and reshape cities of the 21st century.
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Business Models for Sustainability
Nancy Bocken
Human activity is increasingly impacting the environment negatively on all scales. There is an urgent need to transform human activity toward sustainable development. Business has a key role to play in this sustainability transition through technological, product and service, and process innovations, as well as innovative business models. Business models can enable new technologies, and vice versa. These models are therefore important in the transition to sustainability. Business models for sustainability, or synonymously, sustainable business models, take holistic views on how business is operated in relation to its stakeholders, including the society and the natural environment. They incorporate economic, environmental, and social aspects in an organization’s purpose and performance measures; consider the needs of all stakeholders rather than giving priority to owner and shareholder expectations; treat “nature” as a stakeholder; and take a system as well as a firm-level perspective on the way business is conducted. The research field of sustainable business models emerged from fields such as service business models, green and social business models, and concepts such as sharing and circular economy. Academics have argued that the most service-oriented business models can achieve a “factor 10” environmental impact improvement if designed the right way.
Researchers have developed various conceptualizations, typologies, tools, and methods and reviews on sustainable business models. However, sustainable business models are not yet mainstream. Important research areas include the following: (a) tools, methods, and experimentation; (b) the assessment of sustainability impact and rebounds for different stakeholders; (c) sufficiency and degrowth; and (d) the twin revolution of sustainability and digital transition. First, a plethora of tools and approaches are available for inspiration and for creation of sustainable business model designs. Second, in the field of assessment, methods have been based on life cycle thinking considering the supply chain and how a product is (re)used and eventually disposed of. In the field of sufficiency, authors have recognized the importance of moderating consumption through innovative business models to reduce the total need for products, reducing the impact on the environment. Finally, researchers have started to investigate the important interplay between sustainability and digitalization. Because of the potential to achieve a factor 10 environmental impact improvement, sustainable business models are an important source of inspiration for further work, including the upscaling of sustainable business models in established businesses and in new ventures. Understanding how to design better business models and preempting their usage in practice are essential to achieve a desired positive impact. In the field of sufficiency, the macro-impacts of individual and business behavior would need to be better understood. In the area of digital innovation, environmental, societal, and economic values need scrutinization.
Researchers and practitioners can leverage the popularity of this field by addressing these important areas to support the development and roll-out of sustainable business models with significantly improved economic, environmental, and societal impact.
