Editorial

Abstract

Cities and the resources they consume are of paramount importance given that rapid urbanisation is taking place across the globe. Energy is one of those key resources receiving enormous attention. As a contribution towards the ongoing efforts to identify long-term solutions for the energy demands of cities, this themed issue of Energy, on urban transitions to fossil-fuel-free futures, brings together a diverse range of papers that share experiences about how transitions can take place from a multidimensional perspective underpinned by sound technical knowledge of integrating variable energy flow from renewable energy sources while minimising energy losses and maintaining grid stability.The first of these contributions is the paper by Dyer and Ögmundardóttir (2018). The authors share unique experiences about the transition of two medium-sized Scandinavian cities, Sønderborg and Växjö, to becoming almost completely powered by renewable energy, leaving aside transportation. In both these cases, the driving force was not technology but instead community-inspired narratives, stretching back to the 1970s in the case of Växjö. From a series of ethnographic studies, the paper describes the main features of the different and distinct narratives developed by the people and communities of Sønderborg and Växjö from a social, political and cultural perspective. As a guide for planning and implementing future renewable urban energy initiatives, the paper sets out a framework for energy transition comprising local identity, political consensus, external partnerships, inclusive communication, local leadership and champions.In comparison, the paper by Barragán-Escandón et al. (2018) presents a mathematical-based approach for selecting the most appropriate combination of renewable energy sources for cities. Using the Promethee (preference ranking organisation method for enrichment evaluation) method, the authors adapted a multiple-criteria decision analysis (MCDA) methodology that had previously been used at a regional or national scale. The methodology compared the suitability of different renewable energy sources based on technical, economic, environmental and social criteria. The energy sources themselves comprised biomass, biogas, incineration, tidal, wind, photovoltaic (PV) and hydro. The MCAD tool was used to develop a renewable energy strategy for the South American city of Cuenca in Ecuador with the aim of reducing energy imports. In the case of Cuenca, the optimum energy solution based on high solar radiation, presence of river crossings and good waste management practices was a combination of PV, mini hydroelectric and landfill biogas.A similar and complementary multidimensional approach is presented by Ziebell and Singh (2018). Adapting the concept of urban metabolism (UM), the authors have developed a similar large-scale approach for energy use in cities termed urban energy metabolism (UEM). The approach examines energy flows in relation to the physical infrastructures of urban systems as energy sinks as a tool for ur...