Open Access

The Digital Product Passport (DPP) is a concept for collecting and sharing product-related information along the life cycle of a product. DPPs are currently the subject of intense discussion, and various development efforts are being undertaken. These are supported by regulatory activities, especially in the case of the battery passport. The aggregation of product life-cycle data and their respective use, as well as the sharing of these data between companies, entrepreneurs, and other actors in the value chain, is crucial for the creation of a resource-efficient circular economy. Despite the urgent need for such a solution, there is currently little attention given to the digital infrastructure for the creation and handling of the DPPs (i.e., the so-called DPP system). Moreover, there is so far no common understanding of what the requirements for a DPP system are. This is the background and underlying motivation of our paper: we identify the requirements for a DPP system in a structured way, i.e., based on stakeholder involvement and current literature from science and industry. In addition, we compose, categorize, and critically analyze the results, i.e., the list of requirements for DPP systems, in order to identify gaps. Summarized, our research provides insights into the criteria to be considered in the creation of an actual DPP system.

To date, the circular economy has fallen short of its promise to reduce our resource demand and transform our production and consumption system. One key problem is the lack of understanding that highly promising strategies such as refuse, rethink, and reduce can be properly addressed using research on sufficiency. This article argues that a shift in focus is required in research and policy development from consumers who buy and handle circularly designed products to consumption patterns that follow the logic of sufficiency and explain how sufficiency-oriented concepts can be incorporated into existing social practices. The authors show that sufficiency is not necessarily as radical and unattractive as is often claimed, making it a suitable yet underrated strategy for sustainability and the transition to an effective circular economy. The case of urban gardening shows that small interventions can have far-reaching effects and transform consumption patterns as the logic of availability is contested by newly developed concepts of "enoughness" and opposition to "über-availability." The authors propose utilizing comprehensive state-of-the-art theories of consumption and human action when developing strategies and policies to make the circular economy sustainable while being more critical of utilitarian approaches. Using social practice theories that have proven to be beneficial allows human actions to be comprehensively analyzed by recognizing their embeddedness in social and material frameworks; addressing the meaning, competences, and materials of routinized human behavior; and examining indirect effects.

The impending climate catastrophe gives rise to an increased environmental awareness among many designers, who direct their work towards the paradigm of sustainability. While designing with an "ecological lens" is necessarily oriented towards the future, we highlight the past as an inspiring realm to explore. Rather than recycling materials, we encourage the recycling of ideas as a combination of historiographic and speculative design methods. We will present a framework that extends the idea of design as a "projecting" activity into the idea of design as a constant negotiation process about the relevance and appropriateness of current and past technologies. Design revolves not just about what will be, but to a large extent about what should remain and what should recur, or as Jan Michl put it: "seeing design as redesign" (Michl 2002). We will illustrate the thought of designing futures with pasts by means of a research project that aims at developing a refrigerator for circular economy. The refrigerator - as the currently dominant technology to preserve food - will serve as a starting point to show how artefacts and architecture as well as human skills and knowledge in the preparation and preservation of food are historically interlinked. The history of food preservation unfolds not only along the evolution of the refrigerator, but encompasses household techniques like smoking, curing and fermenting, as well as long-forgotten architectural "answers" such as deep-freeze community buildings. We will revisit three historical examples of food preservation and present the method ‘throwing’ past ideas into the future. Three main arguments are presented in this richly illustrated paper: First, that historiography is a form of designing, second, that designing is constituted and influenced by path dependencies (cf. David 1985) that are deeply rooted in the past and third, that the past is a valuable source of inspiration when designing for sustainable development. Looking at history becomes a way of "mental window shopping" (Simon 1985, 188) for approaches that are to be reactivated and transformed.

Four broad categories capture countries' political and economic barriers to quit coal. Use these to tailor solutions.

Research on environmental behaviour is often overlooked in literature on regime destabilization in energy transitions. This study addresses that gap by focusing on socio-political and demographic factors shaping support for carbon regime destabilization policies in one of the most carbon-intensive regions of Europe. Carbon-intensive industries, especially coal mining and coal-based power generation, are often concentrated in a few carbon-intensive regions. Therefore, decarbonization actions will affect those regions particularly strongly. Correspondingly, carbon-intensive regions often exert significant political influence on the two climate mitigation policies at the national level. Focusing on Poland, we investigate socio-political and demographic factors that correlate with the approval or rejection of the two climate mitigation policies: increasing taxes on fossil fuels such as oil, gas, and coal and using public money to subsidize renewable energy such as wind and solar power in Poland and its carbon-intensive Silesia region. Using logistic regression with individual-level data derived from the 2016 European Social Survey (ESS) and the 2014 Chapel Hill Expert Survey (CHES), we find party-political ideology to be an important predictor at the national level but much less so at the regional level. Specifically, voting for right-wing party is not a divisive factor for individual support of the two climate mitigation policies either nationally or regionally. More interestingly, populism is a strong factor in support of increasing taxes on fossil fuel in the carbon-intensive Silesia region but is less important concerning in support of using public money to subsidize renewable energy in Poland overall. These results show the heterogeneity of right-wing party and populism within the support for the two climate mitigation policies. Socio-demographic factors, especially age, gender, education level, employment status, and employment sector, have even more complex and heterogeneous components in support of the two climate mitigation policies at the national and regional levels. Identifying the complex socio-political and demographic factors of climate mitigation policies across different national versus carbon-intensive regional contexts is an essential step for generating in situ decarbonization strategies.

In material development processes, the question if a new alloy is more sustainable than the existing one becomes increasingly significant. Existing studies on metals and alloys show that their composition can make a difference regarding the environmental impact. In this case study, a recently developed air hardening forging steel is used to produce a U-bolt as an example component in automotive engineering. The production process is analyzed regarding the environmental performance and compared with the standard quench and tempering steels 42CrMo4 and 33MnCrB5-2. The analysis is based on results from applying the method of Life Cycle Assessment. First, the production process and the alterations on material, product, and process level are defined. The resulting process flows were quantified and attributed with the environmental impacts covering Carbon Footprint, Cumulative Energy Demand, and Material Footprint as they represent best the resource-, energy- and thus carbon-intensive steel industry. The results show that the development of the air hardening forging steel leads to a higher environmental impact compared to the reference alloys when the material level is considered. Otherwise, the new steel allows changes in manufacturing process, which is why an additional assessment on process level was conducted. It is seen that the air hardening forging steel has environmental savings as it enables skipping a heat treatment process. Superior material characteristics enable the application of lightweight design principles, which further increases the potential environmental savings. The present work shows that the question of the environmental impact does not end with analyzing the raw material only. Rather, the entire manufacturing process of a product must be considered. The case study also shows methodological questions regarding the specification of steel for alloying elements, processes in the metalworking industry and the data availability and quality in Life Cycle Assessment.

Urban transitions and transformations research fosters a dialogue between sustainability transitions theory an inter- and transdisciplinary research on urban change. As a field, urban transitions and transformations research encompasses plural analytical and conceptual perspectives. In doing so, this field opens up sustainability transitions research to new communities of practice in urban environments, including mayors, transnational municipal networks, and international organizations.

Household food waste is determined by a complex set of routinized behaviors, and disruption of these routines may allow for a decrease in this vast amount of food waste. The current study examines such a disruption of household routines: the meal box. The potential of meal boxes to diminish different types of household food waste is investigated for the first time, across different countries. After providing a framework comparing the effects of different types of meals on food waste, we subsequently examine the effects of subscription-based food supply (i.e., meal boxes) on total meal waste as well as on the different types of food waste: preparation, cooking, and plate waste. Our dataset contains 8747 meal observations from 955 households in six countries. Results from a Bayesian multilevel hurdle-lognormal model with random intercept show that, overall, meal boxes reduce total meal waste in comparison to traditionally cooked dinners (38% reduction). Meal boxes especially lower the occurrence and amount of pan-and-pot food that is wasted (i.e., cooking waste), and also lower the amount of meal preparation waste, yet lead to a higher occurrence of both preparation and plate waste compared to traditional meals. This shows how differences between meals affect household food waste, something that has received little prior research attention. Furthermore, whereas most prior research has focused on overall household food waste, our study illustrates that distinguishing between different types of household food waste can provide important new insights.

Transponder-based Aircraft Detection Lighting Systems (ADLS) are increasingly used in wind turbines to limit beacon operation times, reduce light emissions, and increase wind energy acceptance. The systems use digital technologies such as receivers of digital transponder signals, LTE/5G, and other information and communication technology. The use of ADLS will be mandatory in Germany both for new and existing wind turbines with a height of >100 m from 2023 (onshore) and 2024 (offshore), so a nationwide rollout is expected to start during 2022. To fully realize the benefits while avoiding risks and bottlenecks, a thorough and holistic understanding of the efforts required and the impacts caused along the life cycle of an ADLS is essential. Therefore, this study presents the first multi-aspect holistic evaluation of an ADLS. A framework for evaluating digital applications in the energy sector, previously developed by the authors, is refined and applied. The framework is based on multi-criteria analysis (MCA), life cycle assessment (LCA), and expert interviews. On an aggregated level, the MCA results show an overall positive impact from all stakeholders’ perspectives. Most positive impacts are found in the society and politics category, while most negative impacts are of technical nature. The LCA of the ADLS reveals a slightly negative impact, but this impact is negligible when compared to the total life cycle impact of the wind turbines of which the ADLS is a part. Besides the aggregated evaluation, detailed information on potential implementation risks, bottlenecks, and levers for life cycle improvement are presented. In particular, the worldwide scarcity of the required semiconductors, in combination with the general lack of technicians in Germany, lead to the authors’ recommendation for a limited prolongation of the planned rollout period. This period should be used by decision-makers to ensure the availability of technical components and installation capacities. A pooling of ADLS installations in larger regions could improve plannability for manufacturers and installers. Furthermore, an ADLS implementation in other countries could be supported by an early holistic evaluation using the presented framework.

This paper discusses options to increase mitigation ambition in crediting mechanisms that serve the Paris Agreement (PA), such as the Article 6.4 mechanism. Under the Clean Development Mechanism and other crediting mechanisms, baselines have been specified in the form of greenhouse gas (GHG) intensity factors and linked to business-as-usual developments. This means that with increasing production of goods and services through carbon market activities, absolute emissions may increase or fall only slowly. At a global level, such an approach widens the "emissions gap". To enable continued use of emissions intensity baselines in crediting mechanisms while being in line with the PA’s goal to pursue efforts to limit temperature rise to 1.5˚C, we propose to apply an "ambition coefficient" to emissions intensities of technologies when establishing the baseline. This coefficient would decrease to reflect increasing ambition over time, and reach zero when a country needs to reach net zero emissions. Due to the principle of common but differentiated responsibilities and respective capabilities, the coefficient would fall more quickly for developed than for developing countries. The latter would be able to generate emission reduction credits well beyond 2050, while for the former, crediting would stop around 2035 or before. An ambition coefficient approach would generate certainty for carbon market investors and preserve trust in international carbon markets that operate in line with the agreed, long-term ambition of the international climate regime.

Sufficiency measures are potentially decisive for the decarbonisation of energy systems but rarely considered in energy policy and modelling. Just as efficiency and renewable energies, the diffusion of demand-side solutions to climate change also relies on policy-making. Our extensive literature review of European and national sufficiency policies fills a gap in existing databases. We present almost 300 policy instruments clustered into relevant categories and publish them as "Energy Sufficiency Policy Database". This paper provides a description of the data clustering, the set-up of the database and an analysis of the policy instruments. A key insight is that sufficiency policy includes much more than bans of products or information tools leaving the responsibility to individuals. It is a comprehensive instrument mix of all policy types, not only enabling sufficiency action, but also reducing currently existing barriers. A policy database can serve as a good starting point for policy recommendations and modelling, further research is needed on barriers and demand-reduction potentials of sufficiency policy instruments.

Energy Efficiency First (EEF) is an established principle for European Union (EU) energy policy design. It highlights the exploitation of demand-side resources and prioritizes cost-effective options from the demand-side over other options from a societal cost-benefit perspective. However, the involvement of multiple decision-makers makes it difficult to implement. Therefore, we propose a flexible decision-tree framework for applying the EEF principle based on a review of relevant areas and examples. In summary, this paper contributes to applying the EEF principle by defining and distinguishing different types of cases - (1) policy-making, and (2) system planning and investment - identifying the most common elements, and proposing a decision-tree framework that can be flexibly constructed based on the elements for different cases. Finally, we exemplify the application of this framework with two example cases: (1) planning for demand-response in the power sector, and (2) planning for a district heating system.

The transformation of society into sustainable structures is one of the most important tasks for the future. That cities have a decisive role to play in this transformation process has been known at least since Rio 1992. They have enormous pressure to act for change: They are at the same time problem and solution for sustainable development. Currently there is another significant development for cities - the need and external pressure to be "smart", often understood merely as applying the latest digital technologies to become more efficient. The Smart City and the Sustainable City can work hand in hand or hinder each other, depending on their interpretation. In this study we focus on five Smart Cities in Western Germany to get a closer look at how they shape their processes and whether the underlying motivation is to become a technologically Smart City, focus on sustainable development, or both. With the help of the innovation biography research method, we show how cities shape the dynamic process towards forming a Smart City, the role sustainable urban development plays in the process, who the actors involved are, and the important role improved knowledge management then plays for the diffusion of the Smart Sustainable City within the region. It becomes clear how important communication and narratives are both in the process within each City towards forming a Smart Sustainable City and for the first step of diffusion, the adaptation of other cities within the region. This study is intended to serve both as a basis for cross-regional consideration and dialogue for the transfer of successful processes.

Circular economy seems a vital enabler for sustainable use of natural resources which is also important for achieving the 2030 agenda for sustainable development goals. Therefore, a special session addressing issues of "sustainable solutions and remarkable practices in circular economy focusing materials downstream" was held at the 16th International Conference on Waste Management and Technology, where researchers and attendees worldwide were convened to share their experiences and visions. Presentations focusing on many key points such as new strategies, innovative technologies, management methods, and practical cases were discussed during the session. Accordingly, this article compiled all these distinctive presentations and gave insights into the pathway of circular economy towards the sustainable development goals. We summarized that the transition to circular economy can keep the value of resources and products at a high level and minimize waste production; the focus of governmental policies and plans with the involvement of public-private-partnership on 3Rs (reduce, reuse, and recycle) helps to improve the use of natural resources and take a step ahead to approach or achieve the sustainability.

The war in Ukraine is changing the political landscape at breakneck speed. How should politics and society react to high energy prices and a precarious dependence on fossil fuels imports? Can modern societies get by with much less energy? Energy sufficiency can play an important role in answering these questions. The contributions in this Special topic explore sufficiency as an interdisciplinary research topic for energy modeling, scenarios, and policy.

This article enriches the existing literature on the importance and role of the social sciences and humanities (SSH) in renewable energy sources research by providing a novel approach to instigating the future research agenda in this field. Employing a series of in-depth interviews, deliberative focus group workshops and a systematic horizon scanning process, which utilised the expert knowledge of 85 researchers from the field with diverse disciplinary backgrounds and expertise, the paper develops a set of 100 priority questions for future research within SSH scholarship on renewable energy sources. These questions were aggregated into four main directions: (i) deep transformations and connections to the broader economic system (i.e. radical ways of (re)arranging socio-technical, political and economic relations), (ii) cultural and geographical diversity (i.e. contextual cultural, historical, political and socio-economic factors influencing citizen support for energy transitions), (iii) complexifying energy governance (i.e. understanding energy systems from a systems dynamics perspective) and (iv) shifting from instrumental acceptance to value-based objectives (i.e. public support for energy transitions as a normative notion linked to trust-building and citizen engagement). While this agenda is not intended to be—and cannot be—exhaustive or exclusive, we argue that it advances the understanding of SSH research on renewable energy sources and may have important value in the prioritisation of SSH themes needed to enrich dialogues between policymakers, funding institutions and researchers. SSH scholarship should not be treated as instrumental to other research on renewable energy but as intrinsic and of the same hierarchical importance.

Decarbonizing global steel production requires a fundamental transformation. A sectoral climate club, which goes beyond tariffs and involves deep transnational cooperation, can facilitate this transformation by addressing technical, economic and political uncertainties.

Dominant agricultural and food systems lead to continuous resource depletion and unacceptable environmental and social impacts. While current calls for changing agrifood systems are increasingly framed in the context of sustainability transitions, they rarely make an explicit link to transition studies to address these systemic challenges, nor do transition scholars sufficiently address agri-food systems, despite their global pertinence. From this viewpoint, we illustrate several gaps in the agri-food systems debate that sustainability transition studies could engage in. We propose four avenues for research in the next decade of transition research on agri-food systems: 1) Crossscale dynamics between coupled systems; 2) Social justice, equity and inclusion; 3) Sustainability transitions in low- and middle-income countries; 4) Cross-sectoral governance and system integration. We call for a decade of new transition research that moves beyond single-scale and sector perspectives toward more inclusive and integrated analyses of food system dynamics.

Technological breakthroughs and policy measures targeting energy efficiency and clean energy alone will not suffice to deliver Paris Agreement-compliant greenhouse gas emissions trajectories in the next decades. Strong cases have recently been made for acknowledging the decarbonisation potential lying in transforming linear economic models into closed-loop industrial ecosystems and in shifting lifestyle patterns towards this direction. This perspective highlights the research capacity needed to inform on the role and potential of the circular economy for climate change mitigation and to enhance the scientific capabilities to quantitatively explore their synergies and trade-offs. This begins with establishing conceptual and methodological bridges amongst the relevant and currently fragmented research communities, thereby allowing an interdisciplinary integration and assessment of circularity, decarbonisation, and sustainable development. Following similar calls for science in support of climate action, a transdisciplinary scientific agenda is needed to co-create the goals and scientific processes underpinning the transition pathways towards a circular, net-zero economy with representatives from policy, industry, and civil society. Here, it is argued that such integration of disciplines, methods, and communities can then lead to new and/or structurally enhanced quantitative systems models that better represent critical industrial value chains, consumption patterns, and mitigation technologies. This will be a crucial advancement towards assessing the material implications of, and the contribution of enhanced circularity performance to, mitigation pathways that are compatible with the temperature goals of the Paris Agreement and the transition to a circular economy.

How do recent changes in consumption in the wake of the COVID-19 pandemic affect the avoidance of packaging waste? How can an increase in packaging waste be countered and the previous trend towards unpackaged and reusable solutions be revived and promoted? To tackle these questions, we use a systemic approach that regards packaging as a network of interrelated interests of industry (manufacturing and logistics), trade (retail and catering), consumers and the waste management sector. To analyse this network, we applied three methods. First, we analysed secondary sources such as surveys. Second, we conducted semi-structured interviews with seven actors from industry, consumer education and waste management in May and June 2020. Third, we used the questions from the interview guideline to do an online survey among representatives of the public waste management industry.

Model-based scenario analyses of future energy systems often come to deviating results and conclusions when different models are used. This may be caused by heterogeneous input data and by inherent differences in model formulations. The representation of technologies for the conversion, storage, use, and transport of energy is usually stylized in comprehensive system models in order to limit the size of the mathematical problem, and may substantially differ between models. This paper presents a systematic comparison of nine power sector models with sector coupling. We analyze the impact of differences in the representation of technologies, optimization approaches, and further model features on model outcomes. The comparison uses fully harmonized input data and highly simplified system configurations to isolate and quantify model-specific effects. We identify structural differences in terms of the optimization approach between the models. Furthermore, we find substantial differences in technology modeling primarily for battery electric vehicles, reservoir hydro power, power transmission, and demand response. These depend largely on the specific focus of the models. In model analyses where these technologies are a relevant factor, it is therefore important to be aware of potential effects of the chosen modeling approach. For the detailed analysis of the effect of individual differences in technology modeling and model features, the chosen approach of highly simplified test cases is suitable, as it allows to isolate the effects of model-specific differences on results. However, it strongly limits the model's degrees of freedom, which reduces its suitability for the evaluation of fundamentally different modeling approaches.

To limit global warming, the use of carbon capture and storage technologies (CCS) is considered to be of major importance. In addition to the technical-economic, ecological and political aspects, the question of social acceptance is a decisive factor for the implementation of such low-carbon technologies. This study is the first literature review addressing the acceptance of industrial CCS (iCCS). In contrast to electricity generation, the technical options for large-scale reduction of CO2 emissions in the energy-intensive industry sector are not sufficient to achieve the targeted GHG neutrality in the industrial sector without the use of CCS. Therefore, it will be crucial to determine which factors influence the acceptance of iCCS and how these findings can be used for policy and industry decision-making processes. The results show that there has been limited research on the acceptance of iCCS. In addition, the study highlights some important differences between the acceptance of iCCS and CCS. Due to the technical diversity of future iCCS applications, future acceptance research must be able to better address the complexity of the research subject.

In Argentina, renewable energies are promoted as a way of decarbonising the electricity mix and providing reliable energy services. The national goal is to generate 20% of electricity from renewable sources by 2025. However, despite significant natural potential, solar photovoltaic still represents only a small share of Argentina's total electricity generation. Although this picture may look bleak, a wide range of market segments relating to decentralised photovoltaic generation in Argentina have developed. The general objective of this study is to examine the dynamics that currently enable or constrain the diffusion of distributed photovoltaic systems in Argentina. By applying the Technical Innovation System (TIS) approach, the aim is to understand which functions of the system are strong/weak and how these are influenced by endogenous/exogenous system strengths and weaknesses. To that end, a mixed method research strategy is applied. The exploratory sequential research design allows first to explore system strengths and weaknesses based on qualitative approaches, and then to further analyse the contextual embeddedness and the level of importance of the identified variables using quantitative survey instruments. Thereby, this study provides an important analytical method that contributes to a more nuanced understanding of the interdependencies of the TIS. The empirical results indicate that system weaknesses are shaped to a large extent by the overall contextual dynamics - such as political instability, energy subsidies and high inflation rates. System strengths relate to both the TIS itself (particularly knowledge development through pilot projects and market formation through provincial and national support programmes), to contextual relationships (linked to the availability of educational institutions that enable the rapid diffusion of knowledge) and to the importance of rural areas as protected spaces for the application of photovoltaic systems. Consequently, the study highlights the challenges to overcome for the broader diffusion of distributed photovoltaic generation.

To address climate change, the decarbonisation of Germany's existing building stock urgently needs to be prioritised. However, the rate and depth of refurbishment has lagged behind official targets for years. This is a particular problem in the rental sector, where the costs and benefits of energy efficiency measures tend to be unevenly distributed between landlords and tenants (the so-called "landlord-tenant dilemma"). Within the context of the current policy landscape, investments in energy efficiency consequently make most sense for landlords if the upfront costs can be refinanced via increased rental income or reduced vacant periods. This paper seeks to investigate the validity of this statement at city level by using a large dataset from one of Germany’s main internet property platforms to examine how the willingness of tenants to pay for energy efficiency varies across residential locations in the city of Wuppertal. The small-scale spatial analysis highlights the existence of a price premium for energy efficiency in the rental market for apartments; however, this premium is generally small (especially in comparison to other property enhancements, especially visible improvements) or even non-existent in some residential areas. Consequently, investing in energy efficiency is rarely an attractive option for landlords. Therefore, strong policy action, aligned with social and urban development policy objectives, is necessary to establish an effective incentive structure in the market and make investing in energy efficiency more attractive for both landlords and tenants.

The rising popularity and strong increase in the number of electric bicycles make it necessary to consider the built-in resources as well as possible treatments after the use phase. The time lag between the purchase and the occurrence of relevant defects suggests significant increases in defective components. Especially the great dynamics of the market due to regular innovations, product renewals, and the lack of spare parts availability for older models make the long-term use by customers much more difficult than for conventional bicycles. Therefore, it is necessary to analyze circular business models for the electric bicycle market. In this way, the required structures for a sustainable electric bicycle industry can be created so that valuable materials do not go into disposal but undergo a new use phase. Based on the results of "AddRE-Mo-Value Preservation Scenarios for Urban Electromobility of Persons and Loads through Additive Manufacturing and Remanufacturing," a research project funded by the German Federal Ministry of Education and Research, this paper addresses four circular business models, two sales models, and two service models. The guiding research interest of this paper is the combination of remanufacturing and additive manufacturing from a business model perspective, analyzing the extent to which additive remanufacturing can be considered a solution for electric bicycles' circularity. After describing the approach and methods used to develop these four circular business models the business models are described and analyzed using the Business Model Canvas. Based on this analysis, it is shown that the combination of remanufacturing and additive manufacturing can be applied to the electric bicycle market and be integrated into both sales and service models. The description of these business models will help managers design viable business models in the context of sustainable electric bicycles. It also shows that the individual partners within the value chain must collaborate more closely. In the electric bicycle industry, a single company will probably not be able to close the product cycle completely. Further research is needed to develop concepts of the business models and examine their practical feasibility in technical and organizational operations to achieve a circular economy.

Practices and research on measuring traditionally urban sustainability abound, therefore the challenge now is related to how the urban carbon issues are included into current measuring methods, thus there is a need to develop methods for measuring urban low-carbon sustainability. In this paper, a simple method, which is based on low-carbon sustainability index, is developed. The overall urban low-carbon sustainability index is the weighted sum of 11 single indices, and each single index is defined as the indicator assessing the development level against the baseline. The baseline is often the criteria or the minimum requirement of low-carbon sustainability. Case studies in four Chinese cities have put this method into practice, and the results show that all four selected cities fail to pass the testing of sensible low-carbon sustainability rule and they are all in weakly low-carbon sustainable development. Although the four cities have made great progress in their capacity building on pollution control and their capacities on wastewater treatment, main pollutants' removal and household and hazardous wastes treatment are enough to meet the needs of local development, they are all facing the great challenges on using of sustainable energy, offsetting of CO2 emissions and adoptions of nature-based solutions. The method developed by this research is a useful tool for decision makers identifying whether the local development is not on a low-carbon sustainable path.

Every diet has an impact on an individual's health status, the environment as well as on social aspects. In particular, ecological and social concerns are usually only vaguely assessed in the daily routines of out-of-home catering and a systematic sustainability assessment of meals is usually not carried out. Since May 2018, the menu calculator presented in this paper has been supporting stakeholders in various catering establishments with their sustainability assessment. The tool was developed within the NAHGAST project (www.nahgast.de) in cooperation with five practice partners and tested and validated by a total of 120 recipes. This article provides an overview of selected recipes' sustainability assessments (meals with fish and meat as well as vegetarian and vegan meals) and highlights the effects on the ecological, health and social dimensions.

2020 was meant to be the year of climate ambition. Then the COVID-19 pandemic struck, the Glasgow conference was postponed to November 2021, and climate policy generally appeared to have been put on the backburner. But towards the end of the year prospects seemed to brighten with a series of zero-emission pledges and the election of Joe Biden as US President. This article analyses what the year of the pandemic achieved in terms of combating climate change. This article first summarizes the virtual events that were organised to substitute for the physical UNFCCC conferences and what progress was or was not made on the outstanding items of the "Paris rulebook", implementation of the Gender Action Plan, and other items. Subsequently, the article surveys the status of NDC updates and to what extent recovery programmes have been used to advance climate action. Finally, the article takes a closer look at the current dynamics among non-Party actors. In summary, while formal negotiations essentially stopped in the year of the pandemic, the conservation did not. However, implementation is still lagging far behind the ambitious targets that have been set. While implementation is mostly the domain of national policy, the international process has a number of options at its disposal to foster climate action.

The development of digital technologies is accelerating, enabling increasingly profound changes in increasingly short time periods. The changes affect almost all areas of the economy as well as society. The energy sector has already seen some effects of digitalization, but more drastic changes are expected in the next decades. Besides the very positive impacts on costs, system stability, and environmental effects, potential obstacles and risks need to be addressed to ensure that advantages can be exploited while adverse effects are avoided. A good understanding of available and future digital applications from different stakeholders' perspectives is necessary. This study proposes a framework for the holistic evaluation of digital applications in the energy sector. The framework consists of a combination of well-established methods, namely the multi-criteria analysis (MCA), the life cycle assessment (LCA), and expert interviews. The objective is to create transparency on benefits, obstacles, and risks as a basis for societal and political discussions and to supply the necessary information for the sustainable development and implementation of digital applications. The novelty of the proposed framework is the specific combination of the three methods and its setup to enable sound applicability to the wide variety of digital applications in the energy sector. The framework is tested subsequently on the example of the German smart meter roll-out. The results reveal that, on the one hand, the smart meter roll-out clearly offers the potential to increase the system stability and decrease the carbon emission intensity of the energy system. Therefore, the overall evaluation from an environmental perspective is positive. However, on the other hand, close attention needs to be paid to the required implementation and operational effort, the IT (information technology) and data security, the added value for the user, the social acceptance, and the realization of energy savings. Therefore, the energy utility perspective in particular results in an overall negative evaluation. Several areas with a need for action are identified. Overall, the proposed framework proves to be suitable for the holistic evaluation of this digital application.

The target of zero emissions sets a new standard for industry and industrial policy. Industrial policy in the twenty-first century must aim to achieve zero emissions in the energy and emissions intensive industries. Sectors such as steel, cement, and chemicals have so far largely been sheltered from the effects of climate policy. A major shift is needed, from contemporary industrial policy that mainly protects industry to policy strategies that transform the industry. For this purpose, we draw on a wide range of literatures including engineering, economics, policy, governance, and innovation studies to propose a comprehensive industrial policy framework. The policy framework relies on six pillars: directionality, knowledge creation and innovation, creating and reshaping markets, building capacity for governance and change, international coherence, and sensitivity to socio-economic implications of phase-outs. Complementary solutions relying on technological, organizational, and behavioural change must be pursued in parallel and throughout whole value chains. Current policy is limited to supporting mainly some options, e.g. energy efficiency and recycling, with some regions also adopting carbon pricing, although most often exempting the energy and emissions intensive industries. An extended range of options, such as demand management, materials efficiency, and electrification, must also be pursued to reach zero emissions. New policy research and evaluation approaches are needed to support and assess progress as these industries have hitherto largely been overlooked in domestic climate policy as well as international negotiations.

Energy sufficiency is one of the three energy sustainability strategies, next to energy efficiency and renewable energies. We analyse to what extent European governments follow this strategy, by conducting a systematic document analysis of all available European National Energy and Climate Plans (NECPs) and Long-Term Strategies (LTSs). We collect and categorise a total of 230 sufficiency-related policy measures, finding large differences between countries. We find most sufficiency policies in the transport sector, when classifying also modal shift policies to change the service quality of transport as sufficiency policies. Types of sufficiency policy instruments vary considerably from sector to sector, for instance the focus on financial incentives and fiscal instruments in the mobility sector, information in the building sector, and financial incentive/tax instruments in cross-sectoral application. Regulatory instruments currently play a minor role for sufficiency policy in the national energy and climate plans of EU member states. Similar to energy efficiency in recent decades, sufficiency still largely referred to as micro-level individual behaviour change or necessary exogenous trends that will need to take place. It is not treated yet as a genuine field of policy action to provide the necessary framework for enabling societal change.

On the one hand, a large number of companies have committed to achieve net zero emissions and many of them foresee to offset some remaining emissions with carbon credits, suggesting a surge of future demand. Yet, the supply side of the voluntary carbon market is struggling to align its business model with the new legal architecture of the Paris Agreement. This article juxtaposes these two perspectives. It provides an overview of the plans of 482 major companies with some form of neutrality/net zero pledge and traces the struggle on the supply side of the voluntary carbon market to come up with a viable business model that ensures environmental integrity and contributes to achieving the objectives of the Paris Agreement. Our analysis finds that if carbon credits are used to offset remaining emissions against neutrality objectives, these credits need to be accounted against the host countries' Nationally Determined Contributions (NDCs) to ensure environmental integrity. Yet, operationalizing this approach is challenging and will require innovative solutions and political support. Key policy insights: There is a growing mismatch between the faith placed in carbon credits by private sector companies and the continued quest for a common position of the main suppliers of the voluntary carbon market. The voluntary carbon market has not yet found a way to align itself with the new legal architecture of the Paris Agreement in a credible and legitimate way. Public policy support at the national and international level will be needed to operationalize a robust approach for the market’s future activities.

The data centre industry (DCI) has grown from zero in the 1980s, to enabling 60% of the global population to be connected in 2021 via 7.2 million data centres. The DCI is based on a linear economy and there is an urgent need to transform to a Circular Economy to establish a secure supply chain and ensure an economically stable and uninterrupted service, which is particularly difficult in an industry that is comprised of ten insular subsectors. This paper describes the CEDaCI project which was established to address the challenge in this unique sector; this ground-breaking project employs a whole systems approach, Design Thinking and the Double Diamond methods, which rely on people/stakeholder engagement throughout. The paper reviews and assesses the impact of these methods and project to date, using quantitative and qualitative research, via an online sectoral survey and interviews with nine data centre and IT industry experts. The results show that the project is creating positive impact and initiating change across the sector and that the innovative output (designs, business models, and a digital tool) will ensure that sectoral transformation continues; the project methods and structure will also serve as an exemplar for other sectors.

Cities and urban consumers play a central role in the transition to a decarbonized society. Building on existing studies that identify the significant contributions of lifestyle changes, this study proposes a practical methodology for modeling and exploring city-specific carbon footprint reduction pathways through lifestyle changes to decarbonization. It uses an input-output approach with mixed-unit consumption data and the concept of adoption rates, which is applicable to multiple cities with widely available subnational household consumption data. This paper illustrates the use of this methodology by exploring the consumption-based mitigation pathways of 52 Japanese cities with 65 lifestyle change options covering mobility, housing, food, consumer goods, and leisure domains. The results revealed that city-specific impacts of a variety of lifestyle change options can differ by as much as a factor of five among cities, even in the urban context within the same country. Due to this city-level heterogeneity, the priority options of decarbonized lifestyles, such as among shared mobility, low-carbon diets, and longevity of consumer goods, have shifted between cities. The analysis suggests that ambitious urban lifestyle changes can potentially reduce their carbon footprints to meet the 1.5 ℃ target. However, due to the overlaps of mitigation potentials between multiple lifestyle change options, the necessary levels of adoption and coverage are extensive (i.e., adoption rates of 0.6-0.9). Importantly, adopting lifestyle changes with an efficiency strategy (e.g., the introduction of end-use technologies) or sufficiency strategy (e.g., behavioral changes in consumption amounts and modes) alone is not enough; the only way to succeed is through the combination of both strategies. This paper calls for a target-based exploration and identification of city-specific priorities of lifestyle change options to facilitate consumption-oriented mitigation policies and stakeholder actions to address the climate impacts of urban consumption.

The article introduces and exemplifies the approach of evidence-based narratives (EBN). The methodology is a product of co-design between policy-making and science, generating robust intelligence for evidence-based policy-making in the Directorate General for Research and Innovation of the European Commission (DG RTD) under the condition of high uncertainty and fragmented evidence. The EBN transdisciplinary approach tackles practical problems of future-oriented policy-making, in this case in the area of programming for research and innovation addressing the Grand Societal Challenge related to climate change and natural resources. Between 2013 and 2018, the EU-funded RECREATE project developed 20 EBNs in a co-development process between scientists and policy-makers. All EBNs are supported with evidence about the underlying innovation system applying the technological innovation systems (TIS) framework. Each TIS analysis features the innovation, its current state of market diffusion and a description of the innovation investment case. Indicators include potential future market sizes, effects on employment and environmental and social benefits. Based on the innovation and TIS function analyses, the EBNs offer policy recommendations. The article ends with a critical discussion of the EBN approach.

Nowadays, high expectations are set for a digitally enabled circular economy (CE), to enhance resource efficiency. Tracing, tracking, and storing information is most important for this. In this paper, the application of Internet of Things (IoT) and Distributed Ledger Technology (Blockchain) are hence discussed by presenting the case of professional Electrical and Electronic Equipment (EEE) in Italy. Within the context of CE, prevention of electronic waste (WEEE) is extremely relevant as it is a fast-growing waste stream, and the products contain environmentally damaging substances as well as valuable and rare materials. The use of a proper combination of IoT and blockchain can help the producers to keep control on products until EEE end-of-life, while promoting CE strategies and supporting decision-making. Based on the outcomes of five interviews conducted in 2019 to companies of the EEE sector, potential improvements in the EEE end-of-use management are discussed. After providing the definition of requirements for both the technical solution and its testing are provided, three solution variations and the related business models are created and presented, as well as considerations on their environmental and economic impacts. The study shows how digital technologies can support the appropriate and circular management of EEE products and WEEE.

Supply risks and environmental concerns drive the interest in critical raw material recycling in the European Union. Globally, waste electrical and electronic equipment (WEEE) is projected to increase by almost 40% until 2030. This waste stream can be a source of secondary raw materials. The determination of the economic feasibility of recycling and recovering specific materials is a data-intensive, time-consuming, and case-specific task. This study introduced a two-part evaluation scheme consisting of upper continental crust concentrations and raw material prices as a simple tool to indicate the potential and limitations of critical raw material recycling. It was applied to the case of light-emitting diodes (LED) lamps in the EU. A material flow analysis was conducted, and the projected waste amounts were analyzed using the new scheme. Indium, gallium, and the rare earth elements appeared in low concentrations and low absolute masses and showed only a small revenue potential. Precious metals represented the largest revenue share. Future research should confirm the validity and usefulness of the evaluation scheme.

The recently finalized research project "ZRR for municipal waste" aimed at testing and evaluating the automation of municipal waste sorting plants by supplementing or replacing manual sorting, with sorting by a robot with artificial intelligence (ZRR). The objectives were to increase the current recycling rates and the purity of the recovered materials; to collect additional materials from the current rejected flows; and to improve the working conditions of the workers, who could then concentrate on, among other things, the maintenance of the robots. Based on the empirical results of the project, this paper presents the main results of the training and operation of the robotic sorting system based on artificial intelligence, which, to our knowledge, is the first attempt at an application for the separation of bulky municipal solid waste (MSW) and an installation in a full-scale waste treatment plant. The key questions for the research project included (a) the design of test protocols to assess the quality of the sorting process and (b) the evaluation of the performance quality in the first six months of the training of the underlying artificial intelligence and its database.

This paper develops policy measures for a "just transition" based on a case study conducted in Germany's Rhineland lignite mining district. Semi-structured guided interviews served as the methodological approach. Expert interviews were conducted with representatives of citizen initiatives, trade unions and the Federal State of North Rhine-Westphalia. The results reveal the need for policy measures in different areas: First, employees working for subcontractors of the lignite industry have a high risk of losing their jobs because there are virtually no support policies for them. Second, there needs to be more input by civic initiatives regarding the process of structural change. And last, land needs to be prevented from becoming a scarce resource in the Rhineland area due to current mining legislation. We use an actor-centred institutionalist framework to derive governance approaches in line with the needs of various stakeholders.

This paper examines the Global Climate Action Agenda (GCAA) and discusses options to improve sub- and non-state involvement in post-2020 climate governance. A framework that stimulates sub- and non-state action is a necessary complement to national governmental action, as the latter falls short of achieving low-carbon and climate-resilient development as envisaged in the Paris Agreement. Applying design principles for an ideal-type orchestration framework, we review literature and gather expert judgements to assess whether the GCAA has been collaborative, comprehensive, evaluative and catalytic. Results show that there has been greater coordination among orchestrators, for instance in the organization of events. However, mobilization efforts remain event-driven and too little effort is invested in understanding the progress of sub- and non-state action. Data collection has improved, although more sophisticated indicators are needed to evaluate climate and sustainable development impacts. Finally, the GCAA has recorded more action, but relatively little by actors in developing countries. As the world seeks to recover from the COVID-19 crisis and enters a new decade of climate action, the GCAA could make a vital contribution in challenging times by helping governments keep and enhance climate commitments; strengthening capacity for sub- and non-state action; enabling accountability; and realizing sustainable development.

More than 150 municipal utilities (so-called Stadtwerke) were established in Germany from the beginning of the millennium, bringing the total number of Stadtwerke currently established within the country to approximately 900. With responsibility for more than half of the supply of electricity, gas and heat in Germany, these Stadtwerke play a central role in the transformation of the energy sector, or Energiewende. In addition, due to their local and regional ties, Stadtwerke have a particular role to play in energy politics, the economy and across society. This article focuses on the motives behind, and grounds for, the current wave of newly established Stadtwerke. Further, it discusses the factors that were critical to the successful formation of new Stadtwerke in recent years. The results of our survey indicate that the establishment of municipal Stadtwerke is a suitable measure to implement the energy transition at the local level, whereby the concept of public value has a high level of importance for the local decision-makers. Collaboration and cooperation, as well as a resilience-oriented strategy, are important success factors for new Stadtwerke.

Practices of urban experimentation are currently seen as a promising approach to making planning processes more collaborative and adaptive. The practices develop not only in the context of ideal-type concepts of urban experiments and urban labs but also organically in specific governance contexts. We present such an organic case in the city of Wuppertal, Germany, centred around a so-called change-maker initiative, "Utopiastadt." This initiative joined forces with the city administration and collaborated with a private property owner and the local economic development agency in an unusual planning process for the development of a central brownfield site. Ultimately, the consortium jointly published a framework concept that picked up the vision of the "Utopiastadt Campus" as an open-ended catalyst area for pilot projects and experiments on sustainability and city development. The concept was adopted by the city council and Utopiastadt purchased more than 50% of the land. In order to analyse the wider governance context and power struggles, we apply the social-constructivist theory of Strategic Action Fields (SAFs). We focused on the phases of contention and settlement, the shift in interaction forms, the role of an area development board as an internal governance unit and the influences of proximate fields, strategic action, and state facilitation on the development. We aim to demonstrate the potential of the theory of SAFs to understand a long-term urban development process and how an episode of experimentation evolved within this process. We discuss the theory's shortcomings and reflect critically on whether the process contributed to strengthening collaborative and experimental approaches in the governance of city development.

We conduct a systematic, interdisciplinary review of empirical literature assessing evidence on induced innovation in energy and related technologies. We explore links between demand-drivers (both market-wide and targeted); indicators of innovation (principally, patents); and outcomes (cost reduction, efficiency, and multi-sector/macro consequences). We build on existing reviews in different fields and assess over 200 papers containing original data analysis. Papers linking drivers to patents, and indicators of cumulative capacity to cost reductions (experience curves), dominate the literature. The former does not directly link patents to outcomes; the latter does not directly test for the causal impact of on cost reductions). Diverse other literatures provide additional evidence concerning the links between deployment, innovation activities, and outcomes. We derive three main conclusions. (1) Demand-pull forces enhance patenting; econometric studies find positive impacts in industry, electricity and transport sectors in all but a few specific cases. This applies to all drivers - general energy prices, carbon prices, and targeted interventions that build markets. (2) Technology costs decline with cumulative investment for almost every technology studied across all time periods, when controlled for other factors. Numerous lines of evidence point to dominant causality from at-scale deployment (prior to self-sustaining diffusion) to cost reduction in this relationship. (3) Overall Innovation is cumulative, multi-faceted, and self-reinforcing in its direction (path-dependent). We conclude with brief observations on implications for modeling and policy. In interpreting these results, we suggest distinguishing the economics of active deployment, from more passive diffusion processes, and draw the following implications. There is a role for policy diversity and experimentation, with evaluation of potential gains from innovation in the broadest sense. Consequently, endogenising innovation in large-scale models is important for deriving policy-relevant conclusions. Finally, seeking to relate quantitative economic evaluation to the qualitative socio-technical transitions literatures could be a fruitful area for future research.

Despite Germany's Paris Agreement pledge and coal exit legislation, the political debate around carbon-intensive coal remains heated. Coal power and mining have played an important, yet changing role in the history of German politics. In this paper, we analyze the entire parliamentary debate on coal in the German parliament (Bundestag) from its inception in 1949 to 2019. For this purpose we extract the more than 870,000 parliamentary speeches from all protocols in the history of the Bundestag. We identify the 9167 speeches mentioning coal and apply dynamic topic modeling – an unsupervised machine learning technique that reveals the changing thematic structure of large document collections over time - to analyze changes in parliamentary debates on coal over the past 70 years. The trends in topics and their varying internal structure reflect how energy policy was discussed and legitimized over time: Initially, coal was framed as a driver of economic prosperity and guarantee of energy security. In recent years, the debate evolved towards energy transition, coal phase-out and renewable energy expansion. Germany’s smaller and younger parties, the Greens and the Left Party, debate coal more often in the context of the energy transition and climate protection than other parties. Our results reflect trends in other countries and other fields of energy policy. Methodologically, our study illustrates the potential of and need for computational methods to analyze vast corpora of text and to complement traditional social science methods.

The expansion of photovoltaics in German cities has so far fallen short of expectations. The concept of "tenant electricity" ("Mieterstrom" in German), in which tenants of a building are supplied with solar power produced on site, offers great potential here. A study on behalf of the German Federal Ministry for Economic Affairs and Energy estimated the number of tenant households with good conditions for solar tenant electricity at 3.8 million. At the same time, the federal tenant electricity promotion scheme has been in place since 2017, but only about 1% of the annual budget has been claimed. The aim of this study is to identify the barriers for and drivers of diffusion of the tenant electricity model. To this end, a qualitative document analysis and a range of semi-structured expert interviews have been conducted. The theoretical framework used to guide the analysis is the multi-level perspective. The main barrier found for tenant electricity diffusion is the legal framework on the regime level, which also leads to high transaction costs of implementing tenant electricity. A social barrier is the inertia of some residents to actively concern themselves with their electricity supply and switch to a tenant electricity contract. Among its drivers are long-term trends such as the increasing electricity demand in urban areas, technical developments like blockchain technology and the increasing deployment of smart meters, and the EU Renewable Energy Directive. As long as the restrictive legal framework prevails, the further diffusion of tenant electricity will remain limited.

This article aims to analyse the potential for international climate governance to promote the decarbonisation of land transport. It first summarises challenges and barriers that impede the transformation of the sector. On this basis, the article discusses how international governance could potentially assist with overcoming these barriers and mobilising potentials. Subsequently, the article analyses to what extent existing international governance institutions deliver on the potential identified. The analysis finds that while there is a large number of international institutions trying to promote the decarbonisation of land transport, none of them emerge saliently as hubs or core institutions. There is a substantial amount of activity to generate and disseminate knowledge and learning, but the potential for providing guidance and signal, setting rules, providing transparency/accountability and means of implementation could be further exploited. The article concludes with suggestions on how international governance may be strengthened.

In order to calculate the financial return of energy efficiency measures, a cost-benefit analysis (CBA) is a proven tool for investors. Generally, however, most CBAs for investors have a narrow focus, which is - simply speaking - on investment costs compared with energy cost savings over the life span of the investment. This only provides part of the full picture. Ideally, a comprehensive or extended CBA would take additional benefits as well as additional costs into account. The objective of this paper is to reflect upon integrating into a CBA two important cost components: transaction costs and energy efficiency services - and how they interact. Even though this concept has not been carried out to the knowledge of the authors, we even go a step further to try to apply this idea. In so doing, we carried out a meta-analysis on relevant literature and existing data and interviewed a limited number of energy experts with comprehensive experience in carrying out energy services. Even though data is hardly available, we succeeded in constructing three real-world cases and applied an extended CBA making use of information gathered on transaction costs and energy services costs. We were able to show that, despite these additional cost components, the energy efficiency measures are economically viable. Quantitative data was not available on how energy services reduce transaction costs; more information on this aspect could render our results even more positive. Even though empirical and conceptual research must intensify efforts to design an even more comprehensive CBA, these first-of-its-kind findings can counterargue those that believe energy efficiency is not worth it (in monetary terms) due to transaction costs or energy services costs. In fact, this is good news for energy efficiency and for those that seek to make use of our findings to argue in favor of taking up energy efficiency investments in businesses.

Cities are becoming digital and are aiming to be sustainable. How they are combining the two is not always apparent from the outside. What we need is a look from inside. In recent years, cities have increasingly called themselves Smart City. This can mean different things, but generally includes a look towards new digital technologies and claim that a Smart City has various advantages for its citizens, roughly in line with the demands of sustainable development. A city can be seen as smart in a narrow sense, technology wise, sustainable or smart and sustainable. Current city rankings, which often evaluate and classify cities in terms of the target dimensions 2smart" and "sustainable", certify that some cities are both. In its most established academic definitions, the Smart City also serves both to improve the quality of life of its citizens and to promote sustainable development. Some cities have obviously managed to combine the two. The question that arises is as follows: What are the underlying processes towards a sustainable Smart City and are cities really using smart tools to make themselves sustainable in the sense of the 2015 United Nations Sustainability Goal 11? This question is to be answered by a method that has not yet been applied in research on cities and smart cities: the innovation biography. Based on evolutionary economics, the innovation biography approaches the process towards a Smart City as an innovation process. It will highlight which actors are involved, how knowledge is shared among them, what form citizen participation processes take and whether the use of digital and smart services within a Smart City leads to a more sustainable city. Such a process-oriented method should show, among other things, to what extent and when sustainability-relevant motives play a role and which actors and citizens are involved in the process at all.

Flexible, system-oriented operating strategies are becoming increasingly important in terms of achieving a climate-neutral energy system transformation. Solid-oxide electrolysis (SOEC) can play an important role in the production of green synthesis gas from renewable energy in the future. Therefore, it is important to investigate the extent to which SOEC can be used flexibly and which feedback effects and constraints must be taken into account. In this study, we derived a specific load profile from an energy turnaround scenario that supports the energy system. SOEC short-stacks were operated and we investigated the impact that the load profile has on electrical stack performance and stack degradation as well as the product gas composition by means of Fourier-transform infrared spectroscopy. The stacks could follow the grid-related requirement profiles of secondary control power and minute reserves very well with transition times of less than two minutes per 25% of relative power. Only short-term disturbances of the H2/CO ratio were observed during transitions due to the adjustment of feed gases. No elevated degradation effects resulting from flexible operation were apparent over 1300 h, although other causes of degradation were present.

Water availability plays an important role in the expansion planning of utility-scale solar power plants, especially in the arid regions of the Middle East and North Africa. Although these power plants usually account for only a small fraction of local water demand, competition for water resources between communities, farmers, companies, and power suppliers is already emerging and is likely to intensify in future. Despite this, to date there has been a lack of comprehensive studies analyzing interdependencies and potential conflicts between energy and water at local level. This study addresses this research gap and examines the linkages between water resources and energy technologies at local level based on a case study conducted in Ouarzazate, Morocco, where one of the largest solar power complexes in the world was recently completed. To better understand the challenges faced by the region in light of increased water demand and diminishing water supply, a mixed-method research design was applied to integrate the knowledge of local stakeholders through a series of workshops. In a first step, regional socio-economic water demand scenarios were developed and, in a second step, water saving measures to avoid critical development pathways were systematically evaluated using a participatory multi-criteria evaluation approach. The results are a set of water demand scenarios for the region and a preferential ranking of water saving measures that could be drawn upon to support decision-making relating to energy and water development in the region.

The transdisciplinary research mode has gained prominence in the research on and for sustainability transformations. Yet, solution-oriented research addressing complex sustainability problems has become complex itself, with new transdisciplinary research formats being developed and tested for this purpose. Application of new formats offers learning potentials from experience. To this end, we accompanied fourteen research projects conceptualized as real-world labs (RwLs) from 2015 to 2018. RwLs were part of a funding program on "Science for Sustainability" in the German federal state of Baden-Württemberg. Here, we combine conceptual and empirical work to a structured collection of experiences and provide a comprehensive account of RwLs. First, we outline characteristics of RwLs as transformation oriented, transdisciplinary research approach, using experiments, enabling learning and having a long-term orientation. Second, we outline eleven success factors and concrete design notes we gained through a survey of the 14 RwLs: (1) find the right balance between scientific and societal aims, (2) address the practitioners needs and restrictions, (3) make use of the experimentation concept, (4) actively communicate, (5) develop a "collaboration culture", (6) be attached to concrete sites, (7) create lasting impact and transferability, (8) plan for sufficient time and financial means, (9) adaptability, (10) research-based learning, and (11) recognize dependency on external actors. Characteristics and success factors are combined to illustrate practical challenges in RwLs. Third, we show which methods could be used to cope with challenges in RwLs. We conclude discussing the state of debate on RwLs and outline future avenues of research.

The German Energiewende is a deliberate transformation of an established industrial economy towards a nearly CO2-free energy system accompanied by a phase out of nuclear energy. Its governance requires knowledge on how to steer the transition from the existing status quo to the target situation (transformation knowledge). The energy system is, however, a complex socio-technical system whose dynamics are influenced by behavioural and institutional aspects, which are badly represented by the dominant techno-economic scenario studies. In this paper, we therefore investigate and identify characteristics of model studies that make agent-based modelling supportive for the generation of transformation knowledge for the Energiewende. This is done by reflecting on the experiences gained from four different applications of agent-based models. In particular, we analyse whether the studies have improved our understanding of policies' impacts on the energy system, whether the knowledge derived is useful for practitioners, how valid understanding derived by the studies is, and whether the insights can be used beyond the initial case-studies. We conclude that agent-based modelling has a high potential to generate transformation knowledge, but that the design of projects in which the models are developed and used is of major importance to reap this potential. Well-informed and goal-oriented stakeholder involvement and a strong collaboration between data collection and model development are crucial.

Water and energy are two pivotal areas for future sustainable development, with complex linkages existing between the two sectors. These linkages require special attention in the context of the energy transition. Against this background, this paper analyses the role of water availability in the development of solar thermal and photovoltaic power plants for the case of the Draa Valley in southern Morocco. Located in a semi-arid to arid mountainous area, the Drâa Valley faces high water stress - a situation expected to worsen due to climate change. At the same time, the region has one of the greatest potentials for solar energy in the world. To examine whether limited water availability could accelerate or delay the implementation of solar thermal and photovoltaic power plants, this paper compares regional water availability and demand in the Draa Valley for different scenarios, paying particular attention to potential socio-economic development pathways. The Water Evaluation and Planning System software is applied to allocate the water resources in the study region. The water supply is modelled under the Representative Concentration Pathway 8.5 climate scenario, while the water demand for the Drâa Valley is modelled for a combination of three socio-economic and two energy scenarios. The climate scenario describes a significant decrease in water availability by 2050, while the socio-economic and energy scenarios show an increase in water demand. The results demonstrate that during a sequence of dry years the reservoirs water availability is reduced and shortages in water supply can result in high levels of unmet demand. If this situation occurs, oasis farming, water for drinking and energy production could compete directly with each other for water resources. The energy scenarios indicate that the use of dry cooling technologies in concentrated solar power and photovoltaic hybrid systems could be one option for reducing competition for the scarce water resources in the region. However, given that energy generation accounts for only a small share of the regional water demand, the results also suggest that socio-economic demand reduction, especially in the agricultural sector, for example by reducing the cultivated area, will most likely become necessary.

This paper explores how the European Commission promotes the concept of Sustainable Urban Mobility Planning (SUMP) among European cities. Despite the strong uptake of the SUMP concept, mobility-related problems persist in European municipalities. Linking theoretical approaches to understand the diffusion of policies with empirical findings from working with cities in the SUMP context, this article explores channels of policy diffusion and investigates shortcomings related to the respective approaches. Studies on the diffusion, the transfer and the convergence of policies identify formal hierarchy, coercion, competition, learning and networking, and the diffusion of international norms as channels for policy transfer. The findings which are presented in this paper are twofold: First, the paper finds evidence that the Commission takes different roles and uses all mechanisms in parallel, albeit with different intensity. It concludes that the approaches to explain policy diffusion are not competing or mutually exclusive but are applied by the same actor to address different aspects of a policy field, or to reach out to different actors. Second, the article provides first evidence of factors that limit the mechanisms' abilities to directly influence urban mobility systems and mobility behaviour.

At the heart of transition research lies the question of how to "scale up" sustainable alternatives from a protected niche to the creation of mainstream practices. While upscaling processes are often seen as an essential element that contributes to societal transformation, upscaling itself remains a fuzzy concept. We argue that some fundamental dilemmas of upscaling can be identified, for example, the different understanding of the concept by researchers and practitioners. The dilemmas should be addressed in a more reflexive way by those from the worlds of science and practice who are involved in collaborative research settings.

The paper provides an integrated assessment of environmental and socio-economic effects arising from final consumption of food products by European households. Direct and indirect effects accumulated along the global supply chain are assessed by applying environmentally extended input-output analysis (EE-IOA). EXIOBASE 3.4 database is used as a source of detailed information on environmental pressures and world input-output transactions of intermediate and final goods and services. An original methodology to produce detailed allocation matrices to link IO data with household expenditure data is presented and applied. The results show a relative decoupling between environmental pressures and consumption over time and shows that European food consumption generates relatively less environmental pressures outside Europe (due to imports) than average European consumption. A methodological framework is defined to analyze the main driving forces by means of a structural decomposition analysis (SDA). The results of the SDA highlight that while technological developments and changes in the mix of consumed food products result in reductions in environmental pressures, this is offset by growth in consumption. The results highlight the importance of directing specific research and policy efforts towards food consumption to support the transition to a more sustainable food system in line with the objectives of the EU Farm to Fork Strategy.

Decarbonizing transportation in emerging economies will be one of the key challenges in global climate change mitigation efforts. In this paper, pathways are developed towards achieving a 1.5° degree scenario for land-transport for four emerging economies (Brazil, India, Kenya and Vietnam). The aim is to highlight the key opportunities and challenges for low-carbon transport in countries with rapidly growing mobility demand. The main focus of this paper is to reconcile actual and required emission reduction targets and develop plausible pathways to achieve these targets. The paper also identifies potential strategies and measures for these countries to follow these pathways. The analysis considers the contributions of "avoid" (cutting travel growth), "shift" (to lower CO2 modes) and "improve" (vehicle and fuel CO2 characteristics) interventions to decarbonisation scenarios. These scenarios aim to inform renewed Nationally Determined Contributions and shed light on the feasibility of deep decarbonisation pathways that would be in line with the Paris Agreement. Results from this study show that achieving 1.5DS would require dramatic changes in travel patterns, technology and fuels, and major intensification of current policy approaches. Decarbonization solutions will need to include greater use and investment of efficient modes, major shifts toward near-zero carbon fuels such as clean electricity, systems integration, modal shift and urban planning solutions. Although the socio-economic situations and national transport systems differ between the selected countries, some fairly similar strategies appear likely to be core to the mitigation effort, such as rapid growth in light- and heavy-duty vehicle electrification and investments in public transit systems.

The mass roll out of solar PV across the Global South has enabled electricity access for millions of people. In the right context, Small Wind Turbines (SWTs) can be complementary, offering the potential to generate at times of low solar resource (night, monsoon season, winter, etc.) and increasing the proportion of the total energy system that can be manufactured locally. However, many contextual factors critically affect the viability of the technology, such as the extreme variability in the wind resource itself and the local availability of technical support. Therefore, performing a detailed market analysis in each new context is much more important. The Wind Empowerment Market Assessment Methodology (WEMAM) is a multi-scalar, transdisciplinary methodology for identifying the niche contexts where small wind can make a valuable contribution to rural electrification. This paper aims to inform the development of WEMAM with a critical review of existing market assessment methodologies. By breaking down WEMAM into its component parts, reflecting upon its practical applications to date and drawing upon insights from the literature, opportunities where it could continue to evolve are highlighted. Key opportunities include shifting the focus towards development outcomes; creating community archetypes; localised studies in high potential regions; scenario modelling and MCDA ranking of proposed interventions; participatory market mapping; and applying socio-technical transitions theory to understand how the small wind niche can break through into the mainstream.

Effective actions to mitigate climate change are urgently needed, especially in the context of cities, which are major sources of global CO2 emissions. Establishing and managing knowledge systems that integrate local knowledge can contribute to establishing more effective responses to climate change as well as transformative change towards sustainability. However, it is still unclear how new forms of urban governance should acquire, store, create, or disseminate knowledge for fostering sustainability transitions effectively. In this study, we present a multilevel knowledge system approach based on design principles informed especially by the knowledge management literature. These address (i) working environments across multiple levels, (ii) knowledge forms and types, and (iii) knowledge processes. We apply this approach to municipal climate action in the German energy transition. In particular, we focus on the operational work of municipal climate action managers of regional centers of Lower Saxony, one of the largest of the 16 federal states, and investigate their involvement in knowledge processes. Based on semi-structured interviews in 14 of the 17 regional centers, we show that structural pre-conditions for successful knowledge management and organizational learning are present. However, we also show that there is a need for improvement regarding (i) the multilevel coordination for accelerating routine operation, (ii) the persistence of local operational knowledge, and (iii) the exploitation of local innovations. Relying on these results, we offer general recommendations for municipal climate action and suggest that policies should (i) rely on local knowledge for effective decision-making, (ii) foster multilevel exchanges of explicit and tacit knowledge for implementation, and (iii) enable open-ended learning processes that leverage local innovations for creating usable transformational knowledge.

Biofuels and electrification are potential ways to reduce CO2 emissions from the transport sector, although not without limitations or associated problems. This paper describes a life-cycle analysis (LCA) of the Brazilian urban passenger transport system. The LCA considers various scenarios of a wholesale conversion of car and urban bus fleets to 100% electric or biofuel (bioethanol and biodiesel) use by 2050 compared to a business as usual (BAU) scenario. The LCA includes the following phases of vehicles and their life: fuel use and manufacturing (including electricity generation and land-use emissions), vehicle and battery manufacturing and end of life. The results are presented in terms of CO2, nitrous oxides (NOx) and particulate matter (PM) emissions, electricity consumption and the land required to grow the requisite biofuel feedstocks. Biofuels result in similar or higher CO2 and air pollutant emissions than BAU, while electrification resulted in significantly lower emissions of all types. Possible limitations found include the amount of electricity consumed by electric vehicles in the electrification scenarios.

Integrated assessment models (IAMs) are commonly used by decision makers in order to derive climate policies. IAMs are currently based on climate-economics interactions, whereas the role of social system has been highlighted to be of prime importance on the implementation of climate policies. Beyond existing IAMs, we argue that it is therefore urgent to increase efforts in the integration of social processes within IAMs. For achieving such a challenge, we present some promising avenues of research based on the social branches of economics. We finally present the potential implications yielded by such social IAMs.

Given large potentials of the MENA region for renewable energy production, transitions towards renewables-based energy systems seem a promising way for meeting growing energy demand while contributing to greenhouse gas emissions reductions according to the Paris Agreement at the same time. Supporting and steering transitions to a low-carbon energy system require a clear understanding of socio-technical interdependencies in the energy system as well as of the principle dynamics of system innovations. For facilitating such understanding, a phase model for renewables-based energy transitions in MENA countries, which structures the transition process over time through the differentiation of a set of sub-sequent distinct phases, is developed in this article. The phase model builds on a phase model depicting the German energy transition, which was complemented by insights about transition governance and adapted to reflect characteristics of the MENA region. The resulting model includes four phases ("Take-off renewables", "System integration", "Power to fuel/gases”, "Towards 100% renewables”), each of which is characterized by a different cluster of innovations. These innovations enter the system via three stages of development which describe different levels of maturity and market penetration, and which require appropriate governance. The phase model has the potential to support strategy development and governance of energy transitions in MENA countries in two complementary ways: it provides an overview of techno-economic developments as orienting guidelines for decision-makers, and it adds some guidance as to which governance approaches are suitable for supporting those developments.

Fully decarbonising global power supply is essential to meet the objectives of the Paris Agreement. A wide range of inter- and transnational governance institutions exist that work towards the transformation of the power sector. But are these governance efforts sufficient to address the challenges? To address this question the article first identifies governance needs on the basis of systemic sector-specific transformation challenges and discusses the potential for international governance to address them. Second, the paper surveys existing inter- and transnational institutions and assess to what extent they exploit the potential of international governance. The analysis shows that many of the governance needs are already being satisfied to some extent, particularly with respect to the deployment of renewable energy. It also shows that a significant blind spot remains: the phase-out of fossil fuels for electricity generation. The detailed analysis enables us to identify options for enhancing the governance landscape.

Last year's conference of the global climate change regime took place from 2 until 15 December 2019 in Madrid, Spain. Despite marking a new record for overtime in the history of the UNFCCC, the conference did not only fail to meet the increasing public demand for swift and strong climate action, it also failed on its formal mandate to finalise the Paris rulebook. A record number of issues were left unresolved and shelved for the next session. COP25 thereby highlighted how much work still lies ahead both domestically and internationally if 2020 is to see a step-up in climate action that is consistent with the long-term goal of the Paris Agreement.

This theory note develops a theoretical approach which integrates the negative spillovers that international institutions often impose on each other into our thinking about their normative legitimacy. Our approach draws on the political philosophy of Rainer Forst which revolves around the right to justification. It suggests that regime complexes facilitate the breakup of institution-specific orders of justification by prompting invested actors to justify negative spillovers vis-a-vis each other. Thus, regime complexes enable more encompassing justifications of negative spillovers than stand-alone international institutions. Against this backdrop, we submit that the proliferation of regime complexes represents normative progress in global governance.

On September 17, 2019, EU Competition Commissioner Margrethe Vestager allowed the electricity company Eon to take over and break up RWE subsidiary Innogy under lenientconditions. But there are numerous experts who have a different opinion and argue that the EU Commission approval is a "decision of enormous importance" that will "fundamentally change the entire sector". The result of this decision is that this mega-deal creates two monolithic giants in the German energy sector with unprecedented market power. If one compares the situation with the purchase of the electricity supplier Nuon by Vattenfall in 2009, questions arise. Back then, the competition authorities forced Vattenfall to divest parts of Nuon's business in individual cities, which resulted in the supplier "lekker energie". Following this example, the competition authorities should have consistently forced Eon to sell parts of the business, such as larger distribution companies. A transaction of this magnitude should always be viewed critically in competition law. The legitimate question therefore arises as to why the German and European competition authorities (the Federal Cartel Office, the Federal Network Agency, the Monopolies Commission and the European Competition Commission) faced this deal with barely audible criticism and why they did not react with far-reaching prohibition requirements. "Competition doubts are certainly justified". Because if the two largest German energy groups completely eliminate each other's competition and completely divide up their business areas among themselves, this will have far-reaching consequences for the energy sector. Especially against the background that the energy transition in Germany has so far been characterised by decentralised structures and civic participation (especially in the case of electricity generation from renewable energies). In this paper, the authors will demonstrate what this Eon/RWE deal means for competition and the energy transition.

With regard to residential energy use in the European Union (EU), most studies consider potential adopters of the technology (e.g., private owners) as being the sole decision-makers in the technology selection. However, during an integrated decision-making process (e.g., a construction project) multiple stakeholders will interact, influencing each other's judgement, thereby making it difficult to discern who is affecting the final decision, and to what extent. The goal of this study is to outline the full network of stakeholders involved in the decision-making process, along with their degree of power and interaction in the technology choice. For this purpose, empirical evidence from a multi-country survey is examined using social network analysis (SNA). The information is compared across building typologies, project types and countries (i.e., Italy, Spain, Germany, Poland, the United Kingdom, France, Belgium and the Netherlands). The results demonstrate that, in EU residential buildings, potential adopters of the technology are not the only stakeholders involved in the technology selection. They are in all instances in communication with multiple stakeholders, some of whom also hold a high level of power in the decision (i.e., key persuaders). Furthermore, their level of power and communication varies substantially across building typologies, project types and countries.

Businesses like Airbnb have shown that a successful circular economy (CE) business can operate exclusively online. Although online communication and web appearance attributes have been subject to academic research given accelerated digitization, there is still a lack of knowledge about online attributes and their role in facilitating CE. We close the portrayed knowledge gap by conducting a discrete-choice experiment with best to worst scaling and focusing on the effect of CE experience on the perception of a CE website by ranking nine online attributes, grouped in three subsets. We therefore contribute by identifying online attributes that are perceived as favorable for CE businesses and detect how participation in CE activities affects the perception of these attributes. We find that third-party associated online attributes (e.g., user reviews or third-party guarantees) rank significantly higher throughout CE consumption patterns of the sample, being always amongst the top three attributes. This novel finding on online preferences opens a new direction for further research, as well as allows practitioners to optimize online operations accordingly. Furthermore, we find that users without prior touchpoints with CE have a higher need for information about the business model as compared to CE active users who are more interested in community related attributes.

We conducted a random allocation experiment at fashion week in Berlin in 2017, testing how face-to-face (f2f) communication affects sales of a fashion start-up focusing on second-hand. The experiment revealed that 11% of guests of an f2f event afterwards turned paying customers with an average basket size 11.8% higher than the overall sales event average. We add insights to research on entrepreneurial practice as well as on offline operations in the context of circular consumption in fashion, exposing the leveraging effect of f2f communication for customer acquisition and revenue of start-ups in the field of sustainable fashion.

The decarbonisation of the building stock is an important element for the success of the German Energiewende (energy transition). Despite some progress having been made, the rate of energy renovation falls below the level required to meet political commitments. This gives rise to the question: what deters property owners from making energy efficiency investments and how can the policy framework foster such investments? To answer this question, the paper focuses on a widely neglected property owner group: small private landlords (SPL). Although they manage 37% of all residential rental properties in Germany, very little is known about their decision-making processes for energy efficiency investments. We applied a mixed-method design to identify factors that hindered and supported their investments. In an explorative study, we initially conducted 18 problem-centred interviews. Subsequently, we carried out a postal survey and analysed the questionnaires using a hierarchical linear regression model. The results show that energy renovation is a multi-dimensional decision-making process, which can only be adequately addressed by a comprehensive policy package. To develop such a package, the author recommends that the specific investment behaviour of SPL must be better targeted, their knowledge about energy efficiency investments must be improved through exchange and networking, a sense of responsibility for the neighbourhood must be fostered, and greater focus must be placed on improving local framework conditions

In the light of Germany's chosen path towards the energy transition, the regulatory framework has changed considerably. New players have succeeded in entering the market, and renewable energies have become increasingly competitive. Greater electrification of the transport and heating sectors will be needed in the future to achieve national climate targets. Against this background, Germany's big energy companies need to be sure that their sales will increase. However, they were unable to anticipate this development, and made strategic mistakes in the past. The development of sustainable business models in line with the energy transition failed to materialize. Now it is becoming increasingly clear that companies must create new business models to survive in the long term. These business models have to keep with the tradition, whilst meeting the needs of low-carbon power supplies. In this paper, we will examine the past and future challenges of the four energy companies and develop a proposal for evaluating sustainable business models. For this purpose, we use the multi-level perspective to categorize developments in the electricity market over the last 50 years, and then apply a multi-criteria analysis to derive five suitable business models from the results.

Background: Facing planetary boundaries, we need a sustainable energy system providing its life support function for society in the long-term within environmental limits. Since science plays an important role in decision-making, this study examines the thematic landscape of research on sustainable energy, which may contribute to a sustainability transformation. Understanding the structure of the research field allows for critical reflections and the identification of blind spots for advancing this field. Methods: The study applies a text mining approach on 26533 Scopus-indexed abstracts published from 1990 to 2016 based on a latent Dirichlet allocation topic model. Models with up 1100 topics were created. Based on coherence scores and manual inspection, the model with 300 topics was selected. These statistical methods served for highlighting timely topic trends, differing thematic fields, and emerging communities in the topic network. The study critically reflects the quantitative results from a sustainability perspective. Results: The study identifies a focus on establishing and optimizing the energy infrastructure towards 100% renewable energies through key modern technology areas: materials science, (biological) process engineering, and (digital) monitoring and control systems. Energy storage, photonic materials, nanomaterials, or biofuels belong to the topics with the strongest trends. The study identifies decreasing trends for general aspects regarding sustainable development and related economic, environmental, and political issues. Conclusions: The discourse is latently adopting a technology-oriented paradigm focusing on renewable energy generation and is moving away from the multi-faceted concept of sustainability. The field has the potential to contribute to climate change mitigation by optimizing renewable energy systems. However, given the complexity of these systems, horizontal integration of the various valuable vertical research strands is required. Furthermore, the holistic ecological perspective considering the global scale that has originally motivated research on sustainable energy might be re-strengthened, e.g., by an integrated energy and materials perspective. Beyond considering the physical dimensions of energy systems, existing links from the currently technology-oriented discourse to the social sciences might be strengthened. For establishing sustainable energy systems, future research will not only have to target the technical energy infrastructure but put a stronger focus on issues perceivable from a holistic second-order perspective.

The need for sustainable energy management at the municipal level is growing, in order to meet EU climate goals. Multiple initiatives have been launched to support municipalities in energy planning and strategy development process. Despite available support, research shows mixed results about implementation of plans and strategies. This research paper analyses what targets municipalities set, how they monitor implementation of their sustainable energy action plans (SEAPs) and searches for the most important factors that have enabled or hindered the implementation of local SEAPs at Latvia. The article shows that, in some cases, there is evidence that SEAP development is a project-based activity, supported by external experts. From municipal personnel point of view, it is a project that ends with approved SEAP, but not a part of their future daily routine. Eventually implementation of the plan is difficult, because municipalities lack experience in daily management of energy data, distribution of responsibilities and implementation of procedures. Municipalities also tend to exclude important stakeholders in their SEAPs, like, private sector, household sector and transport sector, which lead to lower targets and lower achievements in GHG reduction.

A significant reduction in greenhouse gas emissions will be necessary in the coming decades to enable the global community to avoid the most dangerous consequences of man-made global warming. This fact is reflected in Germany's 7th Federal Energy Research Program (EFP), which was adopted in 2018. Direct Air Capture (DAC) technologies used to absorb carbon dioxide (CO2) from the atmosphere comprise one way to achieve these reductions in greenhouse gases. DAC has been identified as a technology (group) for which there are still major technology gaps. The intention of this article is to explore the potential role of DAC for the EFP by using a multi-dimensional analysis showing the technology's possible contributions to the German government's energy and climate policy goals and to German industry's global reputation in the field of modern energy technologies, as well as the possibilities of integrating DAC into the existing energy system. The results show that the future role of DAC is affected by a variety of uncertainty factors. The technology is still in an early stage of development and has yet to prove its large-scale technical feasibility, as well as its economic viability. The results of the multi-dimensional evaluation, as well as the need for further technological development, integrated assessment, and systems-level analyses, justify the inclusion of DAC technology in national energy research programs like the EFP.

Nigeria is Africa's largest economy and home to approximately 10% of the un-electrified population of Sub-Saharan Africa. In 2017, 77 million Nigerians or 40% of the population had no access to affordable, reliable and sustainable electricity. In practice, diesel- and petrol-fuelled back-up generators supply the vast majority of electricity in the country. In Nigeria's nationally-determined contribution (NDC) under the Paris Agreement, over 60% of the greenhouse gas emissions (GHG) reductions are foreseen in the power sector. The goal of this study is to identify and critically examine the pathways available to Nigeria to meet its 2030 electricity access, renewables and decarbonization goals in the power sector. Using published data and stakeholder interviews, we build three potential scenarios for electrification and growth in demand, generation and transmission capacity. The demand assumptions incorporate existing knowledge on pathways for electrification via grid extension, mini-grids and solar home systems (SHS). The supply assumptions are built upon an evaluation of the investment pipeline for generation and transmission capacity, and possible scale-up rates up to 2030. The results reveal that, in the most ambitious Green Transition scenario, Nigeria meets its electricity access goals, whereby those connected to the grid achieve a Tier 3 level of access, and those served by sustainable off-grid solutions (mini-grids and SHS) achieve Tier 2. Decarbonization pledges would be surpassed in all three scenarios but renewable energy goals would only be partly met. Fossil fuel-based back-up generation continues to play a substantial role in all scenarios. The implications and critical uncertainties of these findings are extensively discussed.

In recent years, most countries in the Middle East and North Africa (MENA), including Jordan, Morocco and Tunisia, have rolled out national policies with the goal of decarbonising their economies. Energy policy goals in these countries have been characterised by expanding the deployment of renewable energy technologies in the electricity mix in the medium term (i.e., until 2030). This tacitly signals a transformation of socio-technical systems by 2030 and beyond. Nevertheless, how these policy objectives actually translate into future scenarios that can also take into account a long-term perspective up to 2050 and correspond to local preferences remains largely understudied. This paper aims to fill this gap by identifying the most widely preferred long-term electricity scenarios for Jordan, Morocco and Tunisia. During a series of two-day workshops (one in each country), the research team, along with local stakeholders, adopted a participatory approach to develop multiple 2050 electricity scenarios, which enabled electricity pathways to be modelled using Renewable Energy Pathway Simulation System GIS (renpassG!S). We subsequently used the Analytical Hierarchy Process (AHP) within a Multi-Criteria Analysis (MCA) to capture local preferences. The empirical findings show that local stakeholders in all three countries preferred electricity scenarios mainly or even exclusively based on renewables. The findings demonstrate a clear preference for renewable energies and show that useful insights can be generated using participatory approaches to energy planning.

Urban energy systems have been commonly considered to be socio-technical systems within the boundaries of an urban area. However, recent literature challenges this notion in that it urges researchers to look at the wider interactions and influences of urban energy systems wherein the socio-technical sphere is expanded to political, environmental and economic realms as well. In addition to the inter-sectoral linkages, the diverse agents and multilevel governance trends of energy sustainability in the dynamic environment of cities make the urban energy landscape a complex one. There is a strong case then for establishing a new conceptualisation of urban energy systems that builds upon these contemporary understandings of such systems. We argue that the complex systems approach can be suitable for this. In this paper, we propose a pilot framework for understanding urban energy systems using complex systems theory as an integrating plane. We review the multiple streams of urban energy literature to identify the contemporary discussions and construct this framework that can serve as a common ontological understanding for the different scholarships studying urban energy systems. We conclude the paper by highlighting the ways in which the framework can serve some of the relevant communities.

From 6 to 17 November, the 23rd Conference of the Parties (COP23) to the United Nations Framework Convention on Climate Change (UNFCCC) was held in Bonn under the presidency of Fiji. Researchers of the Wuppertal Institute, who attended the conference, have now published an in-depth analysis of the key results of the conference. The report starts by discussing developments regarding the implementation of the Paris Agreement, in particular the negotiations on the detailed "rulebook" for implementing the Agreement. Other key issues addressed at the conference were the support for countries of the Global South in dealing with the effects of climate change (adaptation and climate finance) and preparation of the first global review of climate action that will take place in December this year. In addition, the report discusses recent developments in the wider world that have an impact on the UNFCCC, in particular the rise of pioneer alliances at the intergovernmental and civil society level. Although some progress was achieved regarding the rulebook for implementation of the Paris Agreement, no real breakthrough was made. Therefore, quite some diplomatic work and political leadership will be needed this year to make the adoption of the rulebook at COP24 in Katowice (Poland) possible. This will require quite some tailwind from civil society and the media.

Many countries are increasingly investing in renewable energy technologies to meet growing energy demands and increase the security of their energy supply. This development is also evident in the Middle East and North Africa (MENA) region, where renewable energy targets and policies have evolved rapidly in recent years. There is a steady increase in both the number of planned and implemented solar photovoltaic (PV) but also of solar thermal projects in form of Concentrating Solar Power (CSP) plants. Many of these installations are designed as large utility-scale systems. Despite the fact that these types of large-scale projects can have significant effects on local communities and their livelihoods, the existing research into the social impacts of such large-scale renewable energy infrastructures at local level is limited. However, assessing and managing these impacts is becoming increasingly important to reduce risks to both the affected communities and to the project and businesses activities. In order to provide more robust evidence on the local effects, this research study reviews the social impacts of large-scale renewable energy infrastructure in the MENA region based on a case study of the NOORo I CSP plant in Ouarzazate, Morocco. Data collected during two empirical field studies, in combination with expert interviews and secondary data analysis, provides detailed evidence on the type and significance of livelihood impacts of the NOORo I CSP plant. The analysis results in a consolidated list of 30 impacts and their significance levels for different stakeholder groups including farmers, young people, women, community representatives and owners of small and medium enterprises. The results show that, overall, the infrastructure development was received positively. The review also indicates that factors identified as having effects on the sustainability of local livelihoods are mainly related to information management and benefit distribution, rather than physical or material aspects.

The Port of Rotterdam is an important industrial cluster, comprising mainly oil refining, chemical production and power generation. In 2016, the port's industry accounted for 19% of the Netherlands' total CO2 emissions. The Port of Rotterdam Authority is aware that the cluster is heavily exposed to future decarbonisation policies, as most of its activities focus on trading, handling, converting and using fossil fuels. Based on a study for the Port Authority using a mixture of qualitative and quantitative methods, our article explores three pathways whereby the port's industry can maintain its strong position while significantly reducing its CO2 emissions and related risks by 2050. The pathways differ in terms of the EU's assumed climate change mitigation ambitions and the key technological choices made by the cluster's companies. The focus of the paper is on identifying key risks associated with each scenario and ways in which these could be mitigated.

The Paris Agreement requires mitigation contributions from all Parties. Therefore, the determination of additionality of activities under the market mechanisms of its Article 6 will need to be revisited. This paper provides recommendations on how to operationalize additionality under Article 6. We first review generic definitions of additionality and current approaches for testing of additionality before discussing under which conditions additionality testing of specific activities or policies is still necessary under the new context of the Paris Agreement, that is, in order to prevent increases of global emissions. We argue that the possibility of "hot air" generation under nationally-determined contributions (NDCs) requires an independent check of the NDC's ambition. If the NDC of the transferring country does contain "hot air", or if the transferred emission reductions are not covered by the NDC, a dedicated additionality test should be required. While additionality tests of projects and programmes could continue to be done through investment analysis, for policy instruments new approaches are required. They should be differentiated according to type of policy instrument. For regulation, we suggest calculating the resulting pay-back period for technology users. If the regulation generates investments exceeding a payback period threshold, it could be deemed additional. Similarly, carbon pricing policies that generate a carbon price exceeding a threshold could qualify; for trading schemes an absence of over-allocation needs to be shown. The threshold should be differentiated according to country categories and rise over time.

Green Information Systems in general, and footprint calculators in particular, are promising feedback tools to assist people in adopting sustainable behaviour. Therefore, a Material Footprint model for use in an online footprint calculator was developed by identifying the most important predictors of the Material Footprint of the calculator's users. By means of statistical learning, the analysis revealed that 22 of the 95 predictors identified accounted for 74% of the variance in Material Footprints. Ten predictors out of the 95, mainly from the mobility domain, were capable of showing a prediction accuracy of 61%. The authors conclude that 22 predictors from the areas of mobility, housing and nutrition, as well as sociodemographic information, accurately predict a person's Material Footprint. The short and concise Material Footprint model may help developers and researchers to enhance their information systems with additional items while ensuring the data quality of such applications.

Last year's conference of the global climate change regime took place from 2 until 15 December 2018 in Katowice, Poland. The conference had two main objectives: operationalising the Paris Agreement by adopting detailed rules for its implementation, and starting the process of strengthening Parties' climate protection contributions. This article covers the negotiations on these two sets of issues and also includes a discussion of other recent climate activities by Parties and non-Party actors. Success of the negotiations in Katowice was far from assured, but in the end COP24 concluded with the adoption of the "Katowice Climate Package" setting out detailed guidelines on how to implement its various elements. However, the conference fell short on the first objective, none of the major emitting countries was ready to step up its climate ambition. The most important aspect of the Katowice outcome is therefore that it has brought the wrangling about implementation procedures to a close, making way for the true task at hand: the strengthening of national and international activities to protect the climate and the implementation of the existing pledges. Arguably, a key factor that has been slowing down climate policy is the power of entrenched interests. The article therefore concludes with a reflection on how such barriers to climate action may be overcome and what role future COPs may play in this regard.

The Paris Agreement introduces long-term strategies as an instrument to inform progressively more ambitious emission reduction objectives, while holding development goals paramount in the context of national circumstances. In the lead up to the twenty-first Conference of the Parties, the Deep Decarbonization Pathways Project developed mid-century low-emission pathways for 16 countries, based on an innovative pathway design framework. In this Perspective, we describe this framework and show how it can support the development of sectorally and technologically detailed, policy-relevant and country-driven strategies consistent with the Paris Agreement climate goal. We also discuss how this framework can be used to engage stakeholder input and buy-in; design implementation policy packages; reveal necessary technological, financial and institutional enabling conditions; and support global stocktaking and increasing of ambition.

Research on sustainability transitions has expanded rapidly in the last ten years, diversified in terms of topics and geographical applications, and deepened with respect to theories and methods. This article provides an extensive review and an updated research agenda for the field, classified into nine main themes: understanding transitions; power, agency and politics; governing transitions; civil society, culture and social movements; businesses and industries; transitions in practice and everyday life; geography of transitions; ethical aspects; and methodologies. The review shows that the scope of sustainability transitions research has broadened and connections to established disciplines have grown stronger. At the same time, we see that the grand challenges related to sustainability remain unsolved, calling for continued efforts and an acceleration of ongoing transitions. Transition studies can play a key role in this regard by creating new perspectives, approaches and understanding and helping to move society in the direction of sustainability.

Sulphate aerosols are dominated by SO2 emissions from coal-burning for the Indian electricity sector and they are thought to have a short term but significant, negative impact on South Asian Summer Monsoon rainfall. This reduction in precipitation in turn can lead to reduced economic outputs, primarily through smaller agricultural yields. By bringing together estimates of (a) the impact of sulphate aerosols on precipitation and (b) the observed relationship between monsoon rainfall and GDP, we present a methodology to estimate the possible financial cost of this effect on the Indian economy and on its agricultural sector. Our preliminary estimate is that the derived benefits could be large enough that around 50% of India's SO2 emissions could be economically mitigated at no cost or net benefit, although it should be noted that the large uncertainties in the underlying relationships mean that the overall uncertainty is also large. Comparison of the 1952-1981 and 1982-2011 periods indicates that the Indian economy may now be more resilient to variability of the monsoon rainfall. As such, a case could be made for action to reduce SO2 emissions, particularly in the crucial monsoon period. This would have a significant, positive effect on a crucial and large sector in India's economy and the effects would be visible almost instantly. The recent growth in renewable energy sources in India and the consequent, reduced increase in coal burning means that further financial costs have already been avoided. This impact should be further investigated so that it can be included in cost-benefit analyses of different fuel types in the region. The significant uncertainties associated with these calculations are discussed.

Sustainable Development Goals and the Paris Agreement stand as milestone diplomatic achievements. However, immense discrepancies between political commitments and governmental action remain. Combined national climate commitments fall far short of the Paris Agreement's 1.5/2°C targets. Similar political ambition gaps persist across various areas of sustainable development. Many therefore argue that actions by nonstate actors, such as businesses and investors, cities and regions, and nongovernmental organizations (NGOs), are crucial. These voices have resonated across the United Nations (UN) system, leading to growing recognition, promotion, and mobilization of such actions in ever greater numbers. This article investigates optimistic arguments about nonstate engagement, namely: (a) "the more the better"; (b) "everybody wins"; (c) "everyone does their part"; and (d) "more brings more." However, these optimistic arguments may not be matched in practice due to governance risks. The current emphasis on quantifiable impacts may lead to the under-appreciation of variegated social, economic, and environmental impacts. Claims that everybody stands to benefit may easily be contradicted by outcomes that are not in line with priorities and needs in developing countries. Despite the seeming depoliticization of the role of nonstate actors in implementation, actions may still lead to politically contentious outcomes. Finally, nonstate climate and sustainability actions may not be self-reinforcing but may heavily depend on supporting mechanisms. The article concludes with governance risk-reduction strategies that can be combined to maximize nonstate potential in sustainable and climate-resilient transformations.

The current global momentum for carbon pricing has lately produced innovative hybrids: carbon taxes allowing the use of offsets from emission sources not targeted by the carbon tax for compliance with the tax load. This study aims at filling the knowledge gap in existing literature by exploring the potential impacts of domestic offset components in carbon taxes on mitigation of national emissions, including the country examples Colombia, Mexico and South Africa. The findings indicate that the use of offsets in carbon taxes may significantly influence mitigation of national emissions both positively and negatively. On the one hand, this model may result in real emission reductions from offset projects and positive spillover effects of efforts to reduce emissions from emission sources covered by the carbon tax to other emission sources. Furthermore, the offsetting component can be used as a bargaining chip in political negotiations facilitating the introduction of mitigation policies and measures and/or strengthening their ambition level. On the other hand, it also entails serious risks: Offsetting could compromise the environmental integrity of the carbon tax through low-quality offsets. Furthermore, offsets reduce incentives to curb emissions in the emission sources covered by the carbon tax, potentially leading to carbon lock-in effects. Moreover, an offsetting component could provoke opposition to further climate policies and measures for emission sources generating offsets, as replacing the offsetting component with mandatory emission reduction policies would eliminate revenues from offset credits. General opposition of stakeholder groups to the introduction of offsets may even hinder the introduction of carbon pricing instruments and offsetting altogether. The study identifies options that could be employed to increase potential positive effects of introducing an offset component to a carbon tax and mitigate related risks, pointing to the country examples included, where appropriate.

The potential of mixed-mode office buildings with varying design and control parameters is examined by using an uncertainty analysis in the three climate zones of India. The analysis is in terms of cooling energy consumption, thermal comfort conditions, and natural ventilation hours. Furthermore, influential parameters are identified using sensitivity analysis. In this study, opening the windows enables natural ventilation. Night-time ventilation through the windows is not enabled because these are mostly closed at night. A maximum natural ventilation of 10% of the total building occupancy hours are observed in warm and humid, and hot and dry climates; however, they are slightly higher in the composite climate. A further increase in the number of natural ventilation hours leads to an increase in the occupancy hours outside the Indian Model for Adaptive Comfort model for mixed-mode buildings with at least 90% of occupants are satisfied. There are no occupancy hours outside of 80% of occupants are satisfied. The choice of thermal comfort band is crucial for determining the potential of mixed-mode buildings. The cooling setpoint temperature, building size, window solar heat gain coefficient, and surface properties of exterior surfaces are identified as the more influential parameters than the thermophysical properties of building envelope constructions. Although the building envelope which is in compliance with the Energy Efficient Building Code of India increases energy efficiency during air-conditioning periods, whether it reduces natural ventilation hours, because of overheating during such period remains to be determined.

Transition modelling is an emerging but growing niche within the broader field of sustainability transitions research. The objective of this paper is to explore the characteristics of this niche in relation to a range of existing modelling approaches and literatures with which it shares commonalities or from which it could draw. We distil a number of key aspects we think a transitions model should be able to address, from a broadly acknowledged, empirical list of transition characteristics. We review some of the main strands in modelling of socio-technological change with regards to their ability to address these characteristics. These are: Eco-innovation literatures (energy-economy models and Integrated Assessment Models), evolutionary economics, complex systems models, computational social science simulations using agent based models, system dynamics models and socio-ecological systems models. The modelling approaches reviewed can address many of the features that differentiate sustainability transitions from other socio-economic dynamics or innovations. The most problematic features are the representation of qualitatively different system states and of the normative aspects of change. The comparison provides transition researchers with a starting point for their choice of a modelling approach, whose characteristics should correspond to the characteristics of the research question they face. A promising line of research is to develop innovative models of co-evolution of behaviours and technologies towards sustainability, involving change in the structure of the societal and technical systems.

India's present development trajectory is at a crucial juncture with a requirement to meet the demands of a population of over 1.2 billion while ensuring environmental sustainability. The resulting economic growth over the past two decades has over-exploited finite natural resources and led to tremendous environmental degradation. Therefore, decoupling economic growth from resource consumption is crucial in the transformation towards a green economy. Building construction is one of the most resource-intensive sectors, as well as creating a high impact on the environment. This study analyzes existing mechanisms in India's building construction sector that attempt to decouple economic growth from resource use and environmental impacts. The key contributors for decoupling are analyzed. Recommendations for regulations, market incentives, transparency, data monitoring and capacity-building are provided for an array of policy initiatives targeted at political and financial decision-makers at the national, state and local levels for different buildings.

This paper investigates the multimodal nature of urban congestion and network performance, with the aim of developing practice ready policy tools to alleviate the adverse effects of excess demand, no matter in which mode it realizes. As part of the efforts to get an overall understanding of how congestion is defined in various disciplines, we conduct a literature review of relevant engineering and microeconomics studies. The investigation reveals the main areas where contradiction can be identified between engineering and economics approaches. In a second step, we investigate the results of an expert survey about the principles of congestion analysis from a multimodal perspective. The main contribution of the paper is twofold. First, we draw attention to the pitfalls of oversimplified and narrow viewpoints on congestion. Second, we operationalize these principles in order to enable decision makers to assess the impact of urban transport measures on congestion.

The long-term transition towards a low-carbon transport sector is a key strategy in Europe. This includes the replacement of fossil fuels, modal shifts towards public transport as well as higher energy efficiency in the transport sector overall. While these energy savings are likely to reduce the direct greenhouse gas emissions of transport, they also require the production of new and different vehicles. This study analyses in detail whether final energy savings in the transport sector also induce savings for material resources from nature if the production of future vehicles is considered. The results for 28 member states in 2030 indicate that energy efficiency in the transport sector leads to lower carbon emissions as well as resource use savings. However, energy-efficient transport sectors can have a significant impact on the demand for metals in Europe. An additional annual demand for 28.4 Mt of metal ores was calculated from the personal transport sector in 2030 alone. The additional metal ores from semiprecious metals (e.g., copper) amount to 12.0 Mt, from precious metals (e.g., gold) to 9.1 Mt and from other metals (e.g., lithium) to 11.7 Mt, with small savings for ferrous metal ores (-4.6 Mt).

Ahead of the Conference of Parties (COP) 24 where countries will first take stock of climate action post Paris, this paper assesses India's progress on its nationally determined contribution (NDC) targets and future energy plans. We find that, although India is well on track to meet its NDC pledges, these targets were extremely modest given previous context. Furthermore, there is considerable uncertainty around India's energy policy post 2030 and if current plans for energy futures materialise, the Paris Agreement's 2 degrees goal will be almost certainly unachievable. India's role in international climate politics has shifted from obstructionism to leadership particularly following the announcement of withdrawal by the United States from the Paris Agreement, but analysis reveals that India's "hard" actions on the domestic front are inconsistent with its "soft" actions in the international climate policy arena. Going forward, India is likely to face increasing calls for stronger mitigation action and we suggest that this gap can be bridged by strengthening the links between India's foreign policy ambitions, international climate commitments, and domestic energy realities.

An index of accessibility-based vulnerability is created based on a definition of transport-user vulnerability regarding transport accessibility created for the EMPOWER project, in order to assess the project's key performance indicator of the inclusion of vulnerable people in the project's scheme. The objective of the index is to account for various individual vulnerability aspects, but also for the "multi-dimensionality" of vulnerability, i.e. individuals may be vulnerable because of one specific aspect (e.g., disability), or they may be vulnerable because of multiple aspects which, if assessed in isolation, wouldn't classify the individual as vulnerable. Users of the project scheme in the Dutch city of Enschede are surveyed on, inter alia, their vulnerability based on this definition, according to their income, mobility budget, physical mobility, age, gender, living situation, nation of birth, and education. According to individual questions, 1% to 54% (single parents and females, respectively) of respondents have some level of vulnerability. According to the index, 23–36% of respondents can be considered to be vulnerable. Suitably modified for local conditions, the index is relevant to cities, especially quickly developing cities where congestion reduction is or has been a priority, insofar as it offers a way of measuring and monitoring the vulnerability of the users of their transport system. Finally, steps to adapt the index to other settings (cities or countries) are discussed.

Digital platforms may yield a host of advantages in putting circular economy into effect. This paper analyses the related chances and discusses requirements of digital platforms for the realization of a circular economy. It specifically points to potential solutions offered by digital platforms for existing barriers. From there it identifies issues that need specific attendance to create economically and ecologically functional platforms. Three economically relevant perspectives are discussed for this: a management perspective, a legislative perspective and a social/systems perspective.

The water-energy-food (WEF) nexus is increasingly recognised as a conceptual framework able to support the efficient implementation of the Sustainable Development Goals (SDGs). Despite growing attention paid to the WEF nexus, the role that renewable energies can play in addressing trade-offs and realising synergies has received limited attention. Until now, the focus of WEF nexus discussions and applications has mainly been on national or global levels, macro-level drivers, material flows and large infrastructure developments. This overlooks the fact that major nexus challenges are faced at local level. Aiming to address these knowledge gaps, the authors conduct a systematic analysis of the linkages between small-scale energy projects in developing countries and the food and water aspects of development. The analysis is based on empirical data from continuous process and impact evaluations complemented by secondary data and relevant literature. The study provides initial insights into how to identify interconnections and the potential benefits of integrating the nexus pillars into local level projects in the global south. The study identifies the complex links which exist between sustainable energy projects and the food and water sectors and highlights that these needs are currently not systematically integrated into project design or project evaluation. A more systematic approach, integrating the water and food pillars into energy planning at local level in the global south, is recommended to avoid trade-offs and enhance the development outcomes and impacts of energy projects.

Against the background of an often wasteful use of natural resources, the European Union has made resource efficiency a top policy priority. Policy formulation is, however, at a very early stage in many Member States, with often vague notions of what resource efficiency means, characterised by fragmented instruments and overlapping competencies. This paper develops a conceptual framework for defining, assessing and developing resource efficiency policy mixes. It argues that a mix of policies and instruments is best suited to overcoming the complex challenges of the 21st Century. Such a mix addresses multiple resource domains at a strategic, high level and contains interacting instruments targeting multiple actors, levels of governance and sectors and life-cycle stages of resource use. This paper looks at criteria for effective resource efficiency policy instruments, presents both an indicative policy mix across 9 policy domains and case studies (on environmental harmful subsidies, supply chain efficiency in food systems and product-service systems) and identifies key challenges to overcome trade-offs in instrument design, maximise synergies, reduce conflicts, promote coherence, coordinate activities and move from theory to practice. Research needs are discussed regarding who shall devise, implement, and coordinate such a policy mix, considering negotiating power, timing and complexity.