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This 43rd volume of the International Journal of Sustainable Energy Planning and Management presents contemporary research within the diverse field of energy planning. The issue starts with analyses of an Indian programme targeting the replacement of fossil fuel-based stoves with induction stoves. Another electrification analysis targets maritime transportation and floating offshore charging stations. Third, analyses are presented regarding the potential impacts of household energy savings in Iran, and whether to optimally use savings for unmet demands in industry or for export – or indeed to lower production correspondingly. Two Hungarian studies focus on a comparison of using heat atlas and using measured data for heat planning and on the feasibility of using individual heat pumps as flexibility provider for the electricity system. Taking a Danish case as a starting point, the role of the heating system in the overall energy system transition is analysed and lastly, a study review the literature on city energy planning approaches.

This 42nd volume of the International Journal of Sustainable Energy Planning and Management includes two articles from the 2023 Sustainable Development of Energy, Water and Environmental Systems (SDEWES) conference series as well as two ordinary articles. The two first articles establish links between the energy systems analysis model EnergyPLAN and respectively the Quintel Energy Transition Model (ETM) and urban building energy modelling to form more comprehensive modelling environments. Third, an article addresses energy systems modelling from a more spatial perspective, with the presentation of the ODHeatMap tool to model the spatial characteristics of heat demand particularly in areas where optimal energy planning data may not be available. Lastly, Vietnam’s economy and energy demand is increasing rapidly, and, in this issue, analyses are presented regarding how ambitions measures in renewable energy utilization and energy efficiency improvements have to beer under different scenarios, for Vietnam to reach its carbon dioxide emission reduction goal.

This 41st volume of the International Journal of Sustainable Energy Planning and Management includes three categories of papers: Ordinary submissions, submissions from the 2023 Smart Energy Systems Conference held in Copenhagen, Denmark and a submission from the 2023 Sustainable Development of Energy, Water and Environmental Systems (SDEWES) conference series. The work presented address photo voltaics (PV) in the arctic and in Sweden and electricity system scenarios of Indonesia based on, e.g. PV. Staying with PV a study investigated the interplay between PV and electric vehicles in Denmark. Moving to district heating, two papers address waste heat utilisation and positive energy districts respectively, and finally a study proves into unavoidable carbon dioxide emissions in Austria accounts for carbon capture and storage (CCS) and carbon capture and utilisation (CCUS) needs and possibilities.

With this volume 40 the International Journal of Sustainable Energy Planning and Management can celebrate its 10 years anniversary. In this editorial we take a closer look at the journals impact over its first 10 years of existence and highlight the articles that have made the largest impacts in the scientific community from a citation perspective. The topic of the journal – sustainable energy planning and management – has not decreased in importance over the first ten years of the journal’s existence – and fortunately the results published in the journal has garnered interest and the impact of the journal has significantly increased. In terms of citation, the journals 275 published articles, has received 1484 citations as per March 2024 and nine articles have 40 or more citations in Scopus. CiteScore ranks the journal in the top 10% out of 700+ journals within the topic of Geography, Planning and Development.

The present paper reviews the hot topics at the 18th Conference on Sustainable Development of Energy, Water, and Environment Systems (SDEWES) held from 24 to 29 September 2023 in Dubrovnik, Croatia. The selected papers, including aspects of biomass energy application, energy saving in building, low-carbon development and climate change adaptation, hybrid application of sustainable energy, energy storage system, and other measures in sustainable development, are published in this Special Issue of Energies. The 12 selected papers in Energies and corresponding literature that relates to the above topics and has been published in the most recent year are reviewed. In particular, diversifying energy applications are trending towards comprehensive integration with more efficient clean energy capacities for global energy procurement, which can also offer increased resilience and sustainability, reduce reliance on fossil fuels, mitigate environmental impacts, and enhance energy security through a mix of renewable sources and innovative technologies. Meanwhile, energy storage has become increasingly important, which can manage the intermittent of renewable energy, stabilize the grid, and improve energy security and resilience against disruptions. In addition to conventional solar energy storage, biomass energy storage, building energy storage, water storage, etc., can also reduce the overall energy costs, deferring investments in additional transmission infrastructure.

This 38th volume of the International Journal of Sustainable Energy Planning and Management presents some of the newest work within the planning of future sustainable energy systems based on renewable energy sources. In this issue, we focus on developments in Indonesia within renewable energy exploitation, electricity use in Africa and finally subsidy schemes for renewable energy exploitation in Indonesia

At the local level, energy communities are at the forefront of the European Green Deal strategy offering new opportunities for citizens to get actively involved in energy markets. The scope of this study is to propose a multi-objective optimization framework to minimize both carbon dioxide emissions and total annual costs in an energy community, considering, within different constraints, a wide availability of decision variables including local renewable energy sources, sector coupling, storage and hydrogen. The methodology involves the coupling of the software EnergyPLAN with a multi-objective evolutionary algorithm, considering 2030 and 2050 as target years and modelling a set of eight types of scenarios, each consisting of 100 optimal systems out of 10,000. The case study is an energy community in the European Alps. The results show, on the one hand, the key role of sector coupling technologies such as cogeneration, heat pumps and electric vehicles in exploiting local renewable energy sources and, on the other hand, the higher costs in introducing both electricity storage to achieve a complete decarbonisation and hydrogen as an alternative strategy in the electricity, thermal and transport sectors.

The current applications in the energy sector are based largely on fossil fuels which release greenhouse gas emissions to the atmosphere. To face the issue of global warming, the energy sector has to transfer to and develop sustainable energy solutions that do not release carbon emissions. This is one of the primary motivators for the SDEWES conference as well as for this review, and previous ones, examining the most recent works based on sustainable and green energy production in such fields. The 17th Conference on the Sustainable Development of Energy, Water, and Environment Systems (SDEWES) was held on 6–10 November 2022 in Paphos, Cyprus. The SDEWES conference aims at solving complex and ongoing concerns that approach a long-term perspective and supporting innovative solutions and continuous monitoring and evaluation. This review paper aims at collecting the main presented papers focused on the following hot topics: low-carbon technologies based on renewable and clean-energy systems, including mainly biomass, solar, and wind energy applications; energy storage systems; hydrogen-based systems; energy-saving strategies in buildings; and the adoption of smart management strategies using renewable energy systems. These topics are investigated in order to propose solutions to address the issues of climate change, water scarcity, and energy saving. From the analyzed works, we note that some key issues for sustainable development remain to be further addressed: such as novel and advanced energy storage systems, green hydrogen production, novel low-temperature district heating and cooling networks, novel solar technologies for the simultaneous production of power and high temperature heat, solar desalination for hydrogen production systems, and agrivoltaic systems for the production of power and food.

This 36th volume of the International Journal of Sustainable Energy Planning and Management starts at the global scale with a survey of the economy of the oil industry. Limitations of single-sector analyses of Chile is the focal point of a commentary on a previously published study in the journal Energies. The authors of the commentary find that limitations in literature survey, methodology, and data result in a significant underestimation of, e.g., the potential for photo voltaics. The potential for hydro power is affected by changes in water flows as analysed by Melo, which brings some level concern as hydro power is a key element in Brazil’s renewable energy exploitation effort. Lasty, Dall-Orsoletta et al. look into system dynamic models and whether they include social aspects in the modelling. This is only found in a minority of system dynamic models.

This 35th volume of the International Journal of Sustainable Energy Planning and Management includes work investigating different biomass resource utilisation scenarios for Mexico as well as scenarios for the transition of Thailand. The latter finds significant photo voltaic requirements when factoring in the transition to green hydrogen for transportation. Transportation is also the focal point in a study of Indonesia, finding that cost and emission optimisation are pushing optimum in different directions. Continuing with Indonesia, the country is seeing a rapidly growing electricity demand, and Siregar investigates social, environmental, technical, and economic criteria for the development of the system towards a more sustainable electricity supply. The scenario analyses are largely based on larger societal transitions, but Appiah makes a more concerted effort to investigate the actual investments in renewable energy sources. Lastly, an article focuses on the industrial sector and how energy efficiency may be affected by policies.

This 34th volume of the International Journal of Sustainable Energy Planning and Management includes papers from the 2021 conference on Sustainable Development of Energy, Water and Environmental Systems (SDEWES) held October 10-15, 2021, in Dubrovnik, Croatia as well as the 7th International Conference on Smart Energy Systems held September 21-22 in Copenhagen, Denmark and two normal papers. A focus area of this issue is district heating and district cooling systems, with articles addressing resources for district heating and cooling systems, impacts of having individual district heating metres for consumers and approaches to analysing district heating systems. Another focus area is stakeholder involvement where two groups of researchers focus on stakeholders from an energy island perspective as well as from a positive energy district perspective. Both groups note the importance of factoring in stakeholders when devising transition plans. Plans for increasing the penetration of renewable energy sources for the Estonian, Latvia and Lithuanian systems are analysed using the Backbone model, finding modest increases in system costs. Lastly, an article sets up an indicator system for assessing environmental performance of European Union member states ranking, e.g., Estonian, Latvia and Lithuanian as moderate (Estonia and Latvia) to weak (Lithuania) in terms of sustainable energy performance score, based on 2019 data.

This study analyses the expansion of solar energy in Iran, considering political, economic, social, and technological factors. Due to the prolonged sanctions on Iran, the development of clean energy power plants has been either halted or significantly reduced. Hence, this study aims to identify barriers to the expansion of solar energy power plants and simulate solar power plants using PVsyst (Photovoltaic system) software. The study is unique in its approach of combining technical analysis with social sciences to facilitate the implementation of solar energy expansion in remote areas. This study focuses on two specific areas with high solar radiation, namely Darab and Meybod, which are located in Fars and Yazd provinces, respectively. Solar energy can be generated in these two areas due to their unique location with high levels of solar irritation. To achieve this goal, the technical analyses focuson simulating the performance of a 9 kWp (kilowatt ‘peak’ power output of a system) grid-connected polysilicon(poly-Si) photovoltaic plant for Darab and a 9.90 kWp plant for Meybod. The simulation is carried out to obtain maximum electricity production and evaluate parameters such as incident radiation, performance ratio, energy into the grid, energy output at the array, and losses. The produced energy for Darab was 20.40 MWh/year, with specific production of 2061 kWh/kWp/year, and the performance ratio (PR) was 81.26%. For Meybod, production was 20.70 MWh/year, with specific production of 2091 kWh/kWp/year, and the performance ratio (PR) was 80.88%. Through the PEST analysis, it is evident that strategic planning and appropriate actions are crucial at the provincial, national, and local levels for energy systems’ development. This indicates that both governments and citizens should play an active role in supporting the expansion of energy systems by planning and creating awareness among the public to embrace and adopt energy systems.

This issue presents some of the latest findings within energy planning research and form a special issue from the 2021 5th Annual Conference of the Portuguese Association of Energy Economics as well as for the 2020 Sustainable Development of Energy, Waste and Environmental Systems conference series. The work presented probes into the effects of the European emissions’ trading system on innovation, and the development of the Chinese wind power industry. Notable is also an analysis of people at Portuguese universities revealing lesser knowledge of renewable energy technologies but a more positive attitude towards this among women – and vice versa among men. EnergyPLAN-based energy systems analyses with cases from Iran and Serbia are presented, and different indicators for energy systems analyses are deliberated in a Mexican context. Marine energy developments in Columbia, the United Kingdom, Canada and Denmark are discussed with a focus on siting and barriers. Also, barriers against solar energy exploitation in Indonesia are explored as are barriers against energy savings in Nigeria.

Despite high expectations for the sector, most marine energy technologies remain in the research and development, or at best demonstration, phase. The industry is in a period of stagnation, and requires new approaches to overcome the challenges that inhibit widespread deployment. Small-scale initiatives have proven to be a successful means of developing other renewable technologies but their role in supporting marine energy is not well researched. This paper provides a review of the barriers and opportunities presented by different policy landscapes, financial support mechanisms, markets, key actors, and wider regulatory and governance issues. Semi-structured interviews with marine energy stakeholders from the UK, Canada and Denmark were used to explore the role of small-scale marine energy projects, and were supplemented by interviews with the general public in England. This showed that while marine energy is appropriately scalable for local projects, financing remains a major hurdle. Discretionary local authority finance, as well as other novel options such as crowdfunding, tends to be relatively modest, supporting the argument for small-scale projects. A market for smaller devices exists, particularly for remote communities currently dependent on expensive energy from oil-fired generators. There remains a significant role for small-scale projects in testing the technology, contributing to reductions in cost and environmental risk. Current processes for environmental impact assessment can present a significant hurdle for small projects, but proportionate, adaptive assessments are evolving. Finally, community ownership and public participation have the potential to increase advocacy for the industry, with multi-actor partnerships presenting a positive way forward.

Homes in rural China often have access to water wells for domestic and agricultural use. Given the significant difference in height between the well water and the roof of the house, such an arrangement could be used as a solar-powered pumped-hydro energy generation system. These systems could both limit increases in carbon emissions from coal-powered electricity while alleviating energy insecurity, while providing significant savings to households. The potential for these systems in rural regions across Shaanxi province is investigated by assessing eight key environmental and socioeconomic indicators. The find is that positive impacts across almost all indicators with generally rapid investment payback periods of 6.4–8.1 years, annual net income increases of 314.2 CNY −541.6 CNY per year per household. This research laid a theoretical foundation for the promotion of PV-PH system in Shaanxi Province.

This editorial introduces the 31st volume of the International Journal of Sustainable Energy Planning and Management. This volume reports some of the latest developments in energy systems analyses of smart energy systems and of district heating as well as in methods and analyses using multi-objective optimisation. In one of the analyses, the authors investigate the effects of decentralised storage in district heating systems, finding positive effects on grid design as the impact of peaks can be reduced. Three contributions address the more sociological factors influencing acceptance and energy system development such as ownership, awareness, and moral.

This editorial introduces the main findings from the 30th Volume of the International Journal of Sustainable Energy Planning and Management. This volume probes into analyses of the technical interactions between multi-energy carrier energy hubs and the role and feasibility of cogeneration of heat and power in a Portuguese context. It moves on to analyse the framework for implementing photo voltaic technology and decision processes for implementing PV technology. Lastly, it presents work on the role of renewable energy sources in meeting carbon dioxide emission reduction goals in Iran.

This editorial introduces the main findings from the 29th Volume of the International Journal of Sustainable Energy Planning and Management. The issue includes both contributions to the 2019 Sustainable Development of Energy Water and Environmental Systems conference and ordinary journal submissions. In either case, the research is centred on sustainable development using renewable energy systems – with particular attention to technology assessment, pricing & regulation and systems analyses. Case studies and model development from Austria, Cape Verde, Columbia, and Iran are presented – with varying focal points. Different drive trains for the electrification of the transportation sector are assessed. Lastly, pricing regimes for evolving district heating systems as well as consumer involvement in 4th generation district heating and social factors for implementing building energy conservation policy are considered

This editorial introduces the 28th volume of the International Journal of Sustainable Energy Planning and Management probing into the actors engaged in energy renovation, rural district heating, and hydropower in Sulawesi. Other work address power-to-gas technology, pine needles as a source of biomass in Himalaya and finally how adaptive pricing can impact electricity demand and thus energy system performance.

This special issue presents some of the latest energy planning-related research as presented at the 2019 International Conference on Energy & Environment (ICEE), University of Minho, Portugal, 2019. In this issue, work is presented which investigates policy initiatives’ effects on electricity prices. Other authors apply Modern Portfolio Theory to analyse the energy and environmental policies of the European Union member states. Solar thermal systems are analysed based on a novel costing methodology and lastly carbon dioxide emissions from a Portuguese energy system with further deployment of electric vehicles are assessed.

This editorial introduces the 27th volume of the International Journal of Sustainable Energy Planning and Management, which reports some of the latest developments in energy systems analyses of smart energy systems as well as district heating. The issue looks into district heating in Estonia and Norway – as part in a renewable energy transition and flexibility-providing measure. Other analyses look into future prices of renewable energy-based power production systems and optimal design of carbon-neutral energy systems combing EnergyPLAN and EPLANOpt.

Entire volume in one collated pdf file

This editorial introduces the 25th volume of the International Journal of Sustainable Energy Planning and Management. This volume presents research on low-temperature district heating in China, prospects for energy savings in Aalborg, Denmark, and impacts on heating systems, offshore wind power and electricity interconnection in the Baltic sea, integration of electricity markets in the United States, and finally the modelling of renewable energy systems both on the remote island of Bonaire and in Chile.

Energy efficiency improvements of buildings is widely recognized as an important part of reaching future sustainable energy systems, as these both reduce the need for energy and improve the efficiency of the heat supply. Finding the correct level of efficiency measures, depends on the type of measure, on the supply system typology as well as on the heat supply cost. As this information is often building-specific, most analyses related to energy efficiency in buildings are carried out in relation to specific renovation projects, while energy plans for larger areas make crude assumptions regarding levels of savings and costs. This article aims at improving the latter, by using a detailed heat atlas in combination with specific marginal energy renovation costs, in a study of Aalborg Municipality in Denmark. In the analysis, all buildings in the municipality are mapped at building level and both the marginal energy efficiency measure costs and the marginal heat supply costs are identified. The buildings are then sorted by their supply type, and marginal costs curves on supply and savings are compared to determine the feasible level of efficiency measures in each building. The results show that both the building type and the supply costs have a large influence on the feasible measures. Furthermore, the results show that a demand reduction of 30% in district heating areas, 35% for buildings with heat pumps and 37% for buildings with oil boilers, for the examined buildings, is socio economically feasible in a Business as Usual 2050 Aalborg Municipality scenario.

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This editorial introduces the 23rd volume of the International Journal of Sustainable Energy Planning and Management. This volume presents research on the robustness of energy modelling, firstly through an assessment of the accuracy of heat demand estimations compared to measured data, followed by an examination of assessment of the robustness of energy modelling relative to the results’ dependency on input time series. Subsequently, challenges to the integration of renewable energy are reviewed, followed by a case from Iran investigating a 100% renewable energy system for desalination. Finally, the issues of technology prioritization for energy efficiency purposes and the development of energy indicators are tackled.

This paper introduces contemporary research on smart cities from the special issue of the International Journal of Sustainable Energy Planning and Management organised in conjunction with the EERA Joint Programme on Smart Cities. The topic - Tools, technologies and systems integration for the Smart and Sustainable Cities to come – highlights the variety of research within this field. From a starting point in a discussion on smart cities and smart energy systems, the paper goes on to describe new research findings within the wider area of smart cities and smart energy systems starting with cases of transition, moving on to data requirements and data generation for designing transitions and ending with theories and methodologies for designing transitions

This editorial introduces the 21st volume of the International Journal of Sustainable Energy Planning and Management. This volume present research on overall national energy planning development with a case from Nigeria. This is followed up by a sustainability assessment of nine sample countries. Moving on to the more local scale, potentials and barriers for photo voltaic systems with cases from Germany, Nigeria and Tanzania are presented. Finally, analyses focusing on the spatial dimension of energy system are presented. This last part addresses both the delimitation between rural and city energy systems and how they should combine and the optimal design of district heating systems.

The conference series International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems – abbreviated ECOS has been at the forefront of the scientific development in energy systems for over three decades. 2018 saw the 31st edition of ECOS held in Guimarães, Portugal. The venue received the contribution of over three hundred papers ranging over selected 19 topics, covering aspects related to thermodynamics, energy systems integration and optimization, planning, cogeneration of heat and power, environmental issues, amongst others. A number of the contributions were invited to the present special issue of the International Journal of Sustainable Energy Planning and Management, and eight of these were after the selection and reviewing process considered to bring the best contributions to the field. These articles address rural household appliance ownership, how much flexibility there is in the Bolivian electricity system to accommodate wind power and photo voltaics, national exergy analyses of Bolivia and thermal imagery of buildings to asses heat losses from these. Other work focus on polygeneration system combining renewable energy sources, cogeneration of heat, cooling and power to supply district heating and cooling in a case area in Italy. In the same area, a mobile thermal energy storage using phase change material is proposed as a way to connect heat sources and heat demands. For the future electrification of the transportation sector and for system design, reliable data on driving cycles are required thus methods for assessing these are presented, followed by analyses of high penetrations of electricity in the transportation system through various technological options.

This editorial introduces the 20th volume of the International Journal of Sustainable Energy Planning and Management. Papers included are all from the conference on 4th generation District heating and Smart Energy Systems, Aalborg, 2017, treating the control of heat systems, technical and non-technical barriers to low-temperature district heating. Temperature levels are also key-parameters in an investigation of heat pumps and heat sources for heat pumps in Tallinn. In parallel to apps focusing on electricity systems, an app focusing on heat systems is presented.

Energy planning increasingly revolves around the use of tools for energy system modelling and analysis with a view to generating scenarios to show implications and possibilities for decision makers. Municipalities engage in the transition to renewable energy systems through the formulation of strategies and goals at a local level despite often lacking appropriate tools and resources to conduct the needed complex analyses. Tools for energy system analyses have traditionally been designed either with the scope of national energy systems or detailed project-specific analysis in mind, leaving municipal planners in a state of flux. This study aims to identify important specifications and critical design principles for future energy system modelling tools designed for municipal planners. Through a qualitative case-oriented approach, this study investigates the planning practices of four municipalities. It is found that future tools for municipal planning purposes need to combine the need for systematic analyses with concrete and implementable initiatives while balancing analytical complexity with operational simplicity.

The global COVID-19 pandemic has had strong impacts on national and international freight, construction and tourism industry, supply chains, and has resulted in a rapid decline in the demand for traditional energy sources. In fact, research has outlined that urban areas depend on global supply chains for their day-to-day basic functions, including energy supplies, food and safe access to potable water. The disruption of global supply chains can leave many urban areas in a very vulnerable position, in which their citizens may struggle to obtain their basic supplies, as the COVID-19 crisis has recently shown. Therefore, solutions aiming to enhance local food, water and energy production systems, even in urban environments, have to be pursued. The COVID-19 crisis has also highlighted in the scientific community the problem of people’s exposure to outdoor and indoor pollution, confirmed as a key element for the increase both in the transmission and severity of the contagion, on top of involving health risks on their own. In this context, most nations are going to adopt new preferential policies to stimulate the development of relevant sustainable energy industries, based on the electrification of the systems supplied by renewable energy sources as confirmed by the International Energy Agency (IEA). Thus, while there is ongoing research focusing on a COVID 19 vaccine, there is also a need for researchers to work cooperatively on novel strategies for world economic recovery incorporating renewable energy policy, technology and management. In this framework, the Sustainable Development of Energy, Water and Environment Systems (SDEWES) conference provides a good platform for researchers and other experts to exchange their academic thoughts, promoting the development and improvements on the renewable energy technologies as well as their role in systems and in the transition towards sustainable energy systems. The 14th SDEWES Conference was held in Dubrovnik, Croatia. It brought together around 570 researchers from 55 countries in the field of sustainable development. The present Special Issue of Energies, specifically dedicated to the 14th SDEWES Conference, focuses on four main fields: energy policy for sustainable development, biomass energy application, building energy saving, and power plant and electric systems.

Currently, Kenya depends mainly on oil, geothermal energy and hydro resources for electricity production, however all three have associated issues. Oil-based electricity generation is environmentally harmful, expensive and a burden to the national trade balance. The rivers for hydropower and their tributaries are found in arid and semi-arid areas with erratic rainfall leading to problems of supply security, and geothermal exploitation has cost and risk issues amongst others. Given these problems and the fact that Kenya has a significant yet underexploited potential for photo voltaic (PV)-based power generation, the limited—although growing—exploitation of solar PV in Kenya is explored in this paper as a means of diversifying and stabilising electricity supply. The potential for integration of PV into the Kenyan electricity generation mix is analysed together with the sociotechnical, economic, political, and institutional and policy barriers, which limit PV integration. We argue that these barriers can be overcome with improved and more robust policy regulations, additional investments in research and development, and improved coordination of the use of different renewable energy sources. Most noticeably, storage solutions and other elements of flexibility need to be incorporated to balance the intermittent character of electricity generation based on solar PV.

This editorial introduces the 19th volume of the International Journal of Sustainable Energy Planning and Management. The volume present work on oil and electricity use in Africa, heating and cooling demands for buildings in Algeria, spot and futures markets in the Iberian electricity markets, transportation sector energy scenarios in Indonesia and corporate willingness to adopt renewable energy sources in Nigeria.

This editorial introduces the 18th volume of the International Journal of Sustainable Energy Planning and Management, which addresses the energy mix of Indonesia, the water-energy nexus in the Drina River Basin, the effects of economic crises on electric utilities, the potential for biogas production in Ukraine and the organisation and ownership of community energy projects.

This editorial introduces the 15th volume of the International Journal of Sustainable Energy Planning and Management. The volume is a special issue from the 2017 International Conference on Energy & Environment, Porto, Portugal and it presents work on energy markets, energy financing and accounting of energy projects.

This editorial introduces the 16th volume of the International Journal of Sustainable Energy Planning and Management, which addresses different angles of district heating ranging from the planning of district heating systems and economic incentives for flexible district heating plants to comparisons between low and ultra-low-temperature district heating systems and methods for determining thermal conductivity in district heating pipes.

The Danish energy system is undergoing a transition from a system based on storable fossil fuels to a system based on fluctuating renewable energy sources. At the same time, more of and more of the energy system is becoming electrified; transportation, heating and fuel usage in industry and elsewhere. This article investigates the development of the Danish energy system in a medium year 2030 situation as well as in a long-term year 2050 situation. The analyses are based on scenario development by the Danish Climate Commission. In the short term, it is investigated what the effects will be of having flexible or inflexible electric vehicles and individual heat pumps, and in the long term it is investigated what the effects of changes in the load profiles due to changing weights of demand sectors are. The analyses are based on energy systems simulations using EnergyPLAN and demand forecasting using the Helena model. The results show that even with a limited short-term electric car fleet, these will have a significant effect on the energy system; the energy system’s ability to integrated wind power and the demand for condensing power generation capacity in the system. Charging patterns and flexibility have significant effects on this. Likewise, individual heat pumps may affect the system operation if they are equipped with heat storages. The analyses also show that the long-term changes in electricity demand curve profiles have little impact on the energy system performance. The flexibility given by heat pumps and electric vehicles in the long-term future overshadows any effects of changes in hourly demand curve profiles.

This editorial introduces the 13th volume of the International Journal of Sustainable Energy Planning and Management, which addresses thermal storage systems in district heating systems, simulation of scheduling of energy units as well as the structure of pricing systems for district heating in Sweden. Beyond the area of district heating, the volume probes into the effects of energy price reductions on energy demand in Hungary as well as the geographical distribution of electricity demand and production in Germany.

This issue presents research results from the 8th Conference on Sustainable Development of Energy, Water and Environment Systems – SDEWES - held in Dubrovnik, Croatia in 2013. Topics covered here include the energy situation in the Middle East with a focus in Cyprus and Israel, energy planning methodology with Ireland as a case and the applicability of energy scenarios modelling tools as a main focus, evaluation of energy demands in Italy and finally evaluation of underground cables vs overhead lines and lacking public acceptance of incurring additional costs for the added benefit of having transmission beyond sight.

Islands typically have sensitive energy systems depending on natural surroundings, but innovative technologies and the exploitation of renewable energy (RE) sources present opportunities like self-sufficiency, but also challenges, such as grid instability. Samsø, Orkney, and Madeira are in the transition to increase the RE share towards 100%—however, this is addressed in different ways depending on the local conditions and current development phases in the transition. Scenarios focusing on the short-term introduction of new technologies in the energy systems are presented, where the electricity sector is coupled with the other energy sectors. Here, both smart grid and sector-integrating solutions form an important part in the next 5−15 years. The scenarios are analyzed using the modeling tool EnergyPLAN, enabling a comparison of today’s reference scenarios with 2030 scenarios of higher RE share. By including three islands across Europe, different locations, development stages, and interconnection levels are analyzed. The analyses suggest that the various smart grid solutions play an important part in the transition; however, local conditions, sector integration, and balancing technologies even more so. Overall, the suggestions complement each other and pave the way to reach 100% RE integration for both islands and, potentially, other similar regions.

Several countries have recently realized that the present development paradigm is not sustainable from an environmental and energy point of view. The growing awareness of the population regarding environmental issues is pushing governments worldwide more and more to promote policies aiming at limiting harmful effects of human development. In particular, the rapid increase of the global temperature, especially in the polar regions, and the management of human wastes, mainly plastic in seas, are some of the main points to be addressed by these novel policies. Several actions must be implemented in order to limit such issues. Unfortunately, the recent COP 24 Conference was not successful, but hopefully an agreement will be established in 2020 at the COP 26 Conference. The effort performed by policymakers must be mandatorily supported by the scientific community. In this framework, this paper aims at showing that countries worldwide are trying to negotiate an agreement to increase energy efficiency and reduce greenhouse gas (GHG) emissions. In addition, in this paper all the researchers reported can provide quantitative measures of the actions to be implemented in order to address a sustainable and efficient use of energy. Here, innovations in terms of novel efficient and environmentally friendly technologies mainly based on renewable energy sources have been also investigated. The study also highlights different sectors that have been involved for this aim, such as energy conversion systems, urban areas, mobility, sustainability, water management, social aspects, etc. In this framework, specific conferences are periodically organized in order to provide a forum for discussion regarding these topics. In this area the Sustainable Development of Energy, Water and Environment Systems (SDEWES) conference is the most ordinary conference. The 13th Sustainable Development of Energy, Water and Environment Systems Conference was held in Palermo, Italy in 2018. The current Special Issue of Energies, precisely dedicated to the 13th SDEWES Conference, is based on three main topics: energy policy and energy efficiency in urban areas, energy efficiency in industry and biomass and other miscellaneous energy systems.

This editorial introduces the seventh volume of the International Journal of Sustainable Energy Planning and Management. The volume presents part of the outcome of the project Energy Systems Modelling Research and Analysis (ENSYMORA) funded by the Danish Innovation Fund. The project carried out by 11 university and industry partners has improved the basis for decision-making within energy planning and energy scenario making by providing new and improved tools and methods for energy systems analyses.

District heating systems are prevailing in parts of Northern Europe and this editorial introduces work on the optimisation of such systems in Denmark, Britain and Norway. Focus of two of the articles are on low temperature systems. This is either directly through lowering the forward temperature and analysing system consequences and optimal forward temperatures as in the work of Lund et al. – or it is by the use of the return pipe water for heating in district heating system functioning at relatively high temperature levels, as in the work by Ianakiev on Nottingham. Analyses by Trømborg et al. probe into future Norwegian electricity market prices and their effects on the operation of district heating storage and electric boilers. Finally, Ogundari et al. compare photo voltaic systems to diesel systems in standalone systems for Abuja, Nigeria.

This editorial introduces the 11th volume of the International Journal of Sustainable Energy Planning and Management. The volume addresses smart energy systems and the optimal ways of integrating renewable energy into these. Two of the contributions are from the perspective of energy storage with one arguing that other storage options are preferable to designated electricity storage. This includes thermal storages for house heating and gas and liquid fuel storage for e.g. the transportation sector. Secondly, a paper investigates more narrowly communal vs individual electricity storage in residential PV systems with a view to lowering grid dependency. Lastly, an analysis investigates the role of flexible electricity demand as a means to integrate fluctuating renewable energy sources such as wind and PV.

It is often highlighted how the transition to renewable energy supply calls for significant electricity storage. However, one has to move beyond the electricity-only focus and take a holistic energy system view to identify optimal solutions for integrating renewable energy. In this paper, an integrated cross-sector approach is used to determine the most efficient and least-cost storage options for the entire renewable energy system concluding that the best storage solutions cannot be found through analyses focusing on the individual sub-sectors. Electricity storage is not the optimum solution to integrate large inflows of fluctuating renewable energy, since more efficient and cheaper options can be found by integrating the electricity sector with other parts of the energy system and by this creating a Smart Energy System. Nevertheless, this does not imply that electricity storage should be disregarded but that it will be needed for other purposes in the future.