A significant obstacle to the incorporation of Nexus considerations in planning and policy design is the understanding and acknowledgement of cross-sectoral interdependencies. This chapter explores the importance of disseminating knowledge of the Nexus among key actors from policy, business and civil society, and in formal education contexts. Examples from capacity development activities and Nexus dialogues linked to the implementation of the Climate, Land, Energy and Water systems (CLEWs) framework are presented. Insights from the latter, as well as other initiatives with similar scope of action, are distilled to forward the importance of learning in such an approach. Additionally, the chapter highlights the main aspects to take into account when promoting these types of activities in new Nexus contexts.

The Climate, Land, Energy and Water systems (CLEWs) approach guides the development of integrated assess-ments. The approach includes an analytical component that can be performed using simple accounting methods, soft-linking tools, incorporating cross-systems considerations in sectoral models, or using one modelling tool to represent CLEW systems. This paper describes how a CLEWs quantitative analysis can be performed using one single modelling tool, the Open Source Energy Modelling System (OSeMOSYS). Although OSeMOSYS was pri-marily developed for energy systems analysis, the tool's functionality and flexibility allow for its application to CLEWs. A step-by-step explanation of how climate, land, energy, and water systems can be represented with OSeMOSYS, complemented with the interpretation of sets, parameters, and variables in the OSeMOSYS code, is provided. A hypothetical case serves as the basis for developing a modelling exercise that exemplifies the building of a CLEWs model in OSeMOSYS. System-centred scenario analysis is performed with the integrated model example to illustrate its application. The analysis of results shows how integrated insights can be derived from the quantitative exercise in the form of conflicts, trade-offs, opportunities, and synergies. In addition to the modelling exercise, using the OSeMOSYS-CLEWs example in teaching, training and open science is explored to support knowledge transfer and advancement in the field.

Energy system modeling can be used to develop internally consistent quantified scenarios. These provide key insights needed to mobilise finance, understand market development, infrastructure deployment and the associated role of institutions, and generally support improved policymaking. However, access to data is often a barrier to starting energy system modeling, especially in developing countries, thereby causing delays to decision making. Therefore, this article provides data that can be used to create a simple zero-order energy system model for a range of developing countries in Africa, East Asia, and South America, which can act as a starting point for further model development and scenario analysis. The data are collected entirely from publicly available and accessible sources, including the websites and databases of international organisations, journal articles, and existing modeling studies. This means that the datasets can be easily updated based on the latest available information or more detailed and accurate local data. As an example, these data were also used to calibrate a simple energy system model for Kenya using the Open Source Energy Modeling System (OSeMOSYS) and three stylized scenarios (Fossil Future, Least Cost and Net Zero by 2050) for 2020-2050. The assumptions used and the results of these scenarios are presented in the appendix as an illustrative example of what can be done with these data. This simple model can be adapted and further developed by in-country analysts and academics, providing a platform for future work.

Population growth, urbanization and economic development drive the use of resources. Securing access to essential services such as energy, water, and food, while achieving sustainable development, require that policy and planning processes follow an integrated approach. The 'Climate-, Land-, Energy- and Water-systems' (CLEWs) framework assists the exploration of interactions between (and within) CLEW systems via quantitative means. The approach was first introduced by the International Atomic Energy Agency to conduct an integrated systems analysis of a biofuel chain. The framework assists the exploration of interactions between (and within) CLEW systems via quantitative means. Its multi-institutional application to the case of Mauritius in 2012 initiated the deployment of the framework. A vast number of completed and ongoing applications of CLEWs span different spatial and temporal scales, discussing two or more resource interactions under different political contexts. Also, the studies vary in purpose. This shapes the methods that support CLEWs-type analyses. In this paper, we detail the main steps of the CLEWs framework in perspective to its application over the years. We summarise and compare key applications, both published in the scientific literature, as working papers and reports by international organizations. We discuss differences in terms of geographic scope, purpose, interactions represented, analytical approach and stakeholder involvement. In addition, we review other assessments, which contributed to the advancement of the CLEWs framework. The paper delivers recommendations for the future development of the framework, as well as keys to success in this type of evaluations.

The authors regret two instances of misinterpretation of input data and one formatting error in the previously published paper as titled above. First, the numerical estimates for water use in NYC electricity and natural gas supply were found to be incorrect due to a conversion error in a data file. This error has now been corrected and the estimates have been changed to correctly correspond to the references on which they are based on. These changes have led to a recalculation of indirect water use reduction potentials in the interventions studied in the paper. Second, two errors due to primary data misinterpretation related to the studied green roof intervention have been found and corrected. The first led to an overestimation of the green roofs’ energy use reduction potential in the previously published paper. The second led to an underestimation of their installation cost. These errors have also been corrected and all numerical results for the green roof intervention have been recalculated. In the updated sections 3 and 4 of the original publication (below), Table 2, Table 3, Fig. 2 and Fig. 3 are updated with the new results related to both indirect water use reductions and green roof performance and costs. The text in the below sections have been given minor adjustments to clarify this update. These changes make green roofs a less economically favourable intervention in comparison to the previously published results. It also makes indirect water use reductions relatively smaller compared to direct water use reductions. All other results as well as the conclusions of this paper are still valid and unchanged. Lastly, a typo in writing of Eq. (7) in the manuscript text has been corrected. There was no error in the equation used in the analysis; hence, no numerical results have been effected by this correction. The authors would like to apologise for any inconvenience caused. Corrected writing of Eq. (7), section 2.3.1: [Formula presented] Updated sections of the original publication.

Achieving universal access to electricity by 2030 is a key part of the Agenda for Sustainable Development, and has its own Sustainable Development Goal, SDG 7.1. This is because electricity services are required for almost all aspects of a modern economy, from the cooling of vaccines to irrigation pumping, to manufacturing and running a business. The achievement of SDG 7.1 will require a thoughtful mix of policy, finance, and technology to be designed and implemented at scale. Yet, the pressing need for an electrification ramp-up is not unprecedented. Many countries (now considered “industrialized”) faced similar challenges about a century ago. Although the existing literature covers a great deal of power systems evolution, there is a gap around the specific role and impact of small, isolated power systems in the early stages of electricity uptake. In this paper, we provide insights based on the review of the historical electrification efforts in four (now middle and high-income) countries. The drivers and context of electrification efforts in early stages are described. Those focus particularly on the role of dispersed, small-scale generation systems (mini-grids). Our analysis shows that electrification follows four loosely defined phases, namely: pilot projects, technological roll-out, economic expansion, and social scale-up. We report a selection of historical mistakes and advances that offer lessons of striking importance for today´s energy access efforts, particularly in regards to the development of mini-grids. We find that today, as historically, multi-stakeholder (e.g., planners, regulators, developers, investors, third party actors) collaboration is key and can help build locally adaptable, economically sustainable and community compatible mini-grids that can accelerate—and lower the societal costs of—universal access to electricity.

This paper analyses how local energy and climate actions can affect the use of water and land resources locally, nationally and globally. Each of these resource systems is linked to different Sustainable Development Goals (SDGs); we also explore related SDG interactions. A municipality in Sweden with the ambition of phasing out fossil fuels by year 2030 is used as illustrative case example. The local energy system is modelled in detail and indirect water and land requirements are quantified for three stylised decarbonisation scenarios of pathways to meeting climate and energy requirements (related to SDG13 and SDG7, respectively). Total local, national and global implications are addressed for the use of water and land resources, which relate to SDG6 for water, and SDG2 and SDG15 for land use. We find that the magnitude and location of water and land impacts are largely pathway-dependent. Some scenarios of low carbon energy may impede progress on SDG15, while others may compromise SDG6. Data for the studied resource uses are incoherently reported and have important gaps. As a consequence, the study results are indicative and subject to uncertainty. Still, they highlight the need to recognise that resource use changes targeting one SDG in one locality have local and non-local impacts that may compromise progress other SDGs locally and/or elsewhere in the world.

Notwithstanding current heavy dependence on gas-fired electricity generation in the Eastern African Power Pool (EAPP), hydropower is expected to play an essential role in improving electricity access in the region. Expansion planning of electricity infrastructure is critical to support investment and maintaining balanced consumer electricity prices. Variations in water availability due to a changing climate could leave hydro infrastructure stranded or result in underutilization of available resources. In this study, we develop a framework consisting of long-term models for electricity supply and water systems management, to assess the vulnerability of potential expansion plans to the effects of climate change. We find that the most resilient EAPP rollout strategy corresponds to a plan optimised for a slightly wetter climate compared to historical trends. This study demonstrates that failing to climate-proof infrastructure investments can result in significant electricity price fluctuations in selected countries (Uganda & Tanzania) while others, such as Egypt, are less vulnerable.

Sub-Saharan Africa has been at the epicenter of an ongoing global dialogue around the issue of energy poverty. More than half of the world's population without access to modern energy services lives there. It also happens to be a sub-continent with plentiful renewable energy resource potential. Hydropower is one of them, and to a large extent it remains untapped. This study focuses on the technical assessment of small-scale hydropower (0.01-10 MW) in Sub-Saharan Africa. The underlying methodology was based on open source geospatial datasets, whose combination allowed a consistent evaluation of 712,615 km of river network spanning over 44 countries. Environmental, topological, and social constraints were included in the form of constraints in the optimization algorithm. The results are presented on a country and power pool basis.

Urban water and energy systems are crucial for sustainably meeting basic service demands in cities. This paper proposes and applies a technology-independent “reference resource-to-service system” framework for concurrent evaluation of urban water and energy system interventions and their ‘nexus’ or ‘interlinkages’. In a concrete application, data that approximate New York City conditions are used to evaluate a limited set of interventions in the residential sector, spanning from low-flow toilet shifts to extensive green roof installations. Results indicate that interventions motivated primarily by water management goals can considerably reduce energy use and contribute to mitigation of greenhouse gas emissions. Similarly, energy efficiency interventions can considerably reduce water use in addition to lowering emissions. However, interventions yielding the greatest reductions in energy use and emissions are not necessarily the most water conserving ones, and vice versa. Useful further research, expanding the present analysis should consider a broader set of resource interactions, towards a full climate, land, energy and water (CLEW) nexus approach. Overall, assessing the impacts, trade-offs and co-benefits from interventions in one urban resource system on others also holds promise as support for increased resource efficiency through integrated decision making.