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The Journal of Sustainable Development of Energy, Water and Environment Systems (JSDEWES) is an international journal dedicated to the improvement and dissemination of knowledge on methods, policies and technologies for increasing the sustainability of development by de-coupling growth from natural resources and replacing them with knowledge based economy, taking into account its economic, environmental and social pillars, as well as methods for assessing and measuring sustainability of development, regarding energy, transport, water, environment and food production systems and their many combinations. In total 56 manuscripts were published in Volume XII, all of them reviewed by at least two reviewers. The Journal of Sustainable Development of Energy, Water and Environment Systems would like to thank reviewers for their contribution to the quality of the published manuscripts.

Holistic strategies in energy, water, and environmental systems can enhance climate change mitigation efforts. Recent scientific innovations have opened up numerous pathways toward comprehensive human development. This editorial explores the 18th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES), highlighting eight key topics from eight research articles that showcase the latest scientific advancements. The articles that addressed energy saving, energy efficiency, and clean energy, include (1) Bioethanol burner operating parameters optimization: Effects of burner opening area modulation on heat output and flue gas composition, (2) Integration of photovoltaic panels and biomass-fuelled CHP in an Italian renewable energy community, (3) AI-Driven Innovations in Greenhouse Agriculture: Reanalysis of Sustainability and Energy Efficiency Impacts, and (4) Methodology to assess the impact of urban vegetation on the energy consumption of residential buildings. A case study in a Mediterranean city. One article discussed infrastructure planning: (5) Dynamic Reduction of Network Flow Optimization Problem: Case of Waste-to-Energy Infrastructure Planning in Czech Republic. One article reviewed the effects of national policies on renewable energy communities: (6) How do national policies influence energy community development across Europe? A review on societal, technical, and economical factors. Additionally, other two articles discussed the method for projections of wind power: (7) A copula post-processing method for wind power projections under climate change, and comparative analysis on open/closed loop with thermal load in an elastocaloric device: (8) 2D thermo-fluidynamic rotary model of an elastocaloric cooling device: The energy performances.

The signing of the Paris Agreement represents a consensus on limiting the increase of the average global temperature compared to the preindustrial period. The European Union has set an ambitious goal of achieving climate neutrality by 2050. By 2030, the European Commission's REPowerEU plan aims to accelerate the processes of increasing the share of renewable energy sources, improving energy efficiency, reducing energy use, and, at the same time, diversifying energy sources and increasing electricity connectivity between member states.In order to achieve the stated goals, future energy systems will be based on renewable energy sources, which are characterized by production variability. Such systems require flexibilization technologies that ensure security and stability of supply. In this study, an analysis of how different fuel and technology costs, as well as policy targets, influence the pace of the energy transition dynamic was made on the case study of Croatia, as there was no such previous investigation. Therefore, the goal of the research is to identify the most prominent driver to achieve energy transition targets in Croatia, with an emphasis on the required flexibilization technologies. The investigation has been implemented in the energy planning tool H2RES, a detailed open-source long-term optimization model in a five-year step model based on scenario analysis of different RES and CO2 targets, technology costs, and fuel prices. The results reveal a need for an ambitious energy policy if the goal is to achieve full energy system decarbonization. Currently, high carbon prices and lower technology costs won't be enough to lead the energy transition, without legislative support.

Over the past few decades, there has been significant attention devoted to the development of advanced technologies for achieving sustainable and environmentally friendly energy production. One prominent event in this field was the 17th SDEWES Conference (Sustainable Development of Energy, Water, and Environment Systems), which took place from November 6–10, 2022, in Paphos, Cyprus. This conference served as a gathering for 496 professionals, comprising scientists, researchers, and experts specializing in sustainable development. Participants came from 52 countries spanning six continents, with 349 attending in person and 147 joining virtually. Prof. Neven Duić, the full professor in the University of Zagreb, originated the SDEWES series since 2002, and serves as the associate editor of Energy Storage and Saving (ENSS) from the journal organization in 2021. This special issue (SI) is the second-time collaboration between SDEWES and ENSS. This editorial focuses on collating the key papers presented during the conference, with a particular emphasis on the pivotal topics including review on electrification and decarbonization, geothermal power utilization, thermal energy storage in heat pump, thermo-economic analysis on thermal system of buildings, industrial policymaking for low-emission technologies and mining investment in Latin America. ENSS also has established the SI for 18th SDEWES in 2023. Manuscripts are welcomed to 18th SDEWES held in Dubrovnik, Croatia on September 24–29, 2023.

Scientific research development in energy, water and environmental systems is vital for climate change mitigation and adaptation. In this regard, the outcome of the 17th Conference on Sustainable Development of Energy, Water and Environment Systems was reviewed and presented in this editorial. Examining recent scientific developments, thirteen research articles on this special issue are related to specific topics. The topic of industrial energy reduction potentials and alternative fuels were discussed in the articles 1) Electricity demand reduction through waste heat recovery in olefins plants based on a technology-agnostic approach, 2) Integration of a rSOC-system to industrial processes, 3) Spray combustion of fast-pyrolysis bio-oils under engine-like conditions, 4) Complex aspects of climate change impacts on the cultivation of perennial energy crops in the Czech Republic, while residential and small scale applications were presented in 5) Experimental and theoretical analysis of a micro-cogenerative solar ORC-based unit equipped with a variable speed sliding rotary vane expander, 6) Exergy-Optimum coupling of radiant panels with heat pumps for minimum CO2 emission responsibility and 7) State-of-the-art review of micro to small-scale wind energy harvesting technologies for building integration and 8) Dynamic simulation of a 4th generation district heating network with the presence of prosumers. Potentials of renewable energy increased penetration and measures and strategies for CO2 emissions reduction presented in 9) An evaluation of the synergy between the wave and wind energy along the west Iberian nearshore, 10) Energy efficiency improvement in multi-family houses in Kosovo, 11) Natural lighting performance of vernacular architecture, case study oldtown Pasa, Ecuador, 12) Diagnosis of the building stock using Energy Performance Certificates for urban energy planning in Mediterranean compact cities. Case of study: The city of València in Spain and 13) Carbon insetting as a measure to raise supply chain energy efficiency potentials: Opportunities and challenges.

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.

The critical need to mitigate climate change brings with it prospects to transform societies globally onto more sustainable pathways. The articles in this special issue of e-Prime - Advances in Electrical Engineering, Electronics and Energy provide timely research advances that support integrated approaches for effective climate mitigation based on the sustainable development of energy, water and environment systems. The articles are organized into three main themes: (1) smart energy systems and sector coupling, (2) Energy Systems Modeling and Analysis, and (3) Emission Reduction Strategies and policies.The Decarbonization and Sector Coupling theme includes articles analyzing electrification and heat pump integration in industrial processes, optimization of nuclear-renewable hybrid energy systems, electric vehicle growth projections in Brazil, and impacts on electricity demand and fossil fuel reduction. The Energy Systems Modeling and Analysis theme covers contributions on offshore wind farm design software tools, optimization of future European energy mixes considering risks, climate change impacts on wind resources in the Black Sea region, and visualizations for home electricity monitoring systems. The Resource and Emission Reduction Strategies theme comprises articles evaluating policy instruments for CO2 utilization, machine learning for projecting passenger vehicle fleet growth in Brazil, and resulting energy and emissions outcomes. Together, these articles provide timely research advances across a range of topics relevant to integrated approaches for climate change mitigation through sustainable energy, water and environment systems. The articles emphasize opportunities for decarbonization, renewable energy deployment, resource efficiency, and emission reductions across multiple sectors and systems.

The heating sector of the European Union covers 80% of the household’s final energy consumption, which shows its relevance for the energy transition to the carbon neutral society, as set out in the Green Deal. Since most of the heat demand is located in the high heat density areas, district heating shows to be a promising solution for reducing the environmental impact of this sector, as it enables the utilisation of renewable energy sources and the use of high efficiency production technologies. An especially interesting source for district heating is excess heat from various industries and tertiary sector buildings, which has a significant technical potential. However, to enable excess heat producers to supply their heat to district heating, third-party access needs to be granted, which calls for a deregulated heat market.This work consists of analysing two different bidding strategies which can be applied on the heat market: total cost and marginal cost biding. The focus here is to research the feasibility of the excess heat sources when different bidding strategies are used, especially when low temperature excess heat is considered, which has variable hourly costs due to the electricity demand for operating a heat pump. The results show that, despite the increased capacity factor of low temperature excess heat when marginal cost biding is used, it remains infeasible when supplying heat to the high temperature district heating networks through a heat market. Therefore, lower temperature district heating is a necessity for a feasible utilisation of low temperature excess heat. Finally, the effect of the power market prices on the low temperature excess heat feasibility was analysed and it was shown that it is significant, which led to the conclusion that introducing a higher share of renewables into the power market could foster the utilisation of these heat sources.

As global energy crises and climate change intensify, offshore wind energy, as a renewable energy source, is given more attention globally. The wind power generation system is fundamental in harnessing offshore wind energy, where the control and design significantly influence the power production performance and the production cost. As the scale of the wind power generation system expands, traditional methods are time-consuming and struggle to keep pace with the rapid development in wind power generation systems. In recent years, artificial intelligence technology has significantly increased in the research field of control and design of offshore wind power systems. In this paper, 135 highly relevant publications from mainstream databases are reviewed and systematically analyzed. On this basis, control problems for offshore wind power systems focus on wind turbine control and wind farm wake control, and design problems focus on wind turbine selection, layout optimization, and collection system design. For each field, the application of artificial intelligence technologies such as fuzzy logic, heuristic algorithms, deep learning, and reinforcement learning is comprehensively analyzed from the perspective of performing optimization. Finally, this report summarizes the status of current development in artificial intelligence technology concerning the control and design research of offshore wind power systems, and proposes potential future research trends and opportunities.

The 16th conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES) has been successfully held on October 10−15, 2021 in Dubrovnik, Croatia. The Chair as well as the initiator of SDEWES series, Prof. Neven Duic, who is the professor in the University of Zagreb, Croatia, serves as the associate editor of Energy Storage and Saving (ENSS), and this special issue (SI) is the first-time collaboration between SDEWES and ENSS. A total of 6 papers were selected for publication. This SI in ENSS mainly addressed the topics related to sustainable energy application (e.g., solar photovoltaic, wind and biomass energy), residual reuse, energy saving of direct heating and cooling, thermal energy storage integration and heat exchanger optimization. The series of SDEWES conference provides a good platform to discuss the most recent development in advanced technologies, methods for distinguished researchers in the field of sustainable energy utilization, energy exploitation, energy policy, etc., which has rich experience on soliciting high-quality manuscript. ENSS, which is an international, peer-reviewed Open Access journal, has established the SI for the 17th SDEWES in 2022, and will go on to cooperate with the SDEWES series in 2023. Manuscripts are welcomed to the 18th SDEWES held in Dubrovnik, Croatia on September 24−29, 2023.

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.

Integrated approaches in energy, water and environmental systems can improve the climate change reduction process. New scientific developments and advancements have provided numerous opportunities in the comprehensive human progress direction. In this regard, we have reviewed the 16th Conference on Sustainable Development of Energy, Water and Environment Systems presented in this editorial. Examining recent scientific developments, eight research articles on this special issue are related to eight main topics. The solar energy technology and storage section reviewed the first four articles. These articles include topics such as: 1) advanced technologies to form a new TT PS-TIM window system for adaptive daylight control and advanced thermal insulation combination, 2) using experimental data for field testing located in an area with Mediterranean climate conditions, of newly installed FPVS in these areas, 3) possibilities described in short rotation of willow type and energy crop Miscanthus cultivation dedicated to former coal mining areas, 4) using solar and geothermal energy with boiling water purification and reverse osmosis. Furthermore, the following four articles are reviewed in the energy management systems section. These articles include topics such as, 5) deep analysis of facial expression and eye tracking using samples of non-expert participants to determine emotions caused by electricity consumption graphs in different time scales, 6) studying the electric vehicles (EVs) main life cycle activities using an exploratory survey and their potential inequities, 7) the biodiesel fuel production from waste sardine fish oil using methanol, ethanol or isopropanol and a solid heterogeneous catalyst prepared using eggshell and copper oxide [CaCu(OCH3)2] is analyzed. Finally, 8) biotechnology microalgae have been studied in 70-litre vertical photobioreactors that use unsupplemented secondary brewery wastewater as growth media using two collecting cells mechanically methods under hydrothermal (autohydrolysis) and dilute acid hydrolysis.

The aim of this study was to analyse specific greenhouse gas emissions savings for a variety of agricultural residues, industrial by-products, and municipal biowaste. One of the most viable alternatives to fossil fuels is bioenergy, particularly biogas produced by the anaerobic digestion of renewable feedstocks. The revised Renewable Energy Directive (D 2018/2001) recognizes that biogas production from agricultural residues, livestock production, and industrial by-products is an acknowledged greenhouse gas mitigation technology in cases where their use results in a certain level of specific greenhouse gas savings. This study delivered values for the maximum transport distance of agricultural residues and industrial by-products to achieve the greenhouse gas (GHG) emissions-saving requirement defined by Directive 2018/2001. It analysed the greenhouse gas emissions reduction for numerous feedstocks for which Directive 2018/2001 has not defined the default and typical values but which could be used as sustainable substitutes for currently dominantly used maize silage in biogas production. The results obtained in this work define the maximum transport and distribution distance for which biogas produced from considered feedstocks achieved required specific greenhouse gas emissions savings (80%), compared with fossil fuel comparator. The obtained results can be used as the constraints in the optimisation of the biomass supply chains for the feedstocks considered in this work.

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.

The ongoing climate change, together with the global increase in energy consumption and unpredictable fossil fuel prices have been the main drivers for the implementation of power exchange, market coupling, energy efficiency measures and larger use of renewable energy. All these targets bring up the need for the development of new modelling frameworks and governance systems that will be based on competitive, secure and sustainable national action plans. For this purpose, the Dispa-SET model has been applied to six countries in the Western Balkans region. In the first scenario, the model has been validated for the year 2010. The second scenario has been developed according to the targets from national energy strategies for the years 2020 and 2030, while the third scenario has been developed with the purpose of determining the maximum share of renewable energy sources in the regional power mix. Simulation results indicate that the integration of additional wind and solar capacities, compared to the short and long-term national strategies for the years 2020 and 2030, can be achieved without compromising the stability of the system.

Recycling and energy recovery of waste plastic are major categories of modern solid waste management systems. Since the lower heating values of plastics are around 30 MJ/kg, equivalent to traditional solid fuels, such as petroleum coke, coal and charcoal, waste plastics are considered as potential fossil fuels alternatives in various industrial sectors. Already nowadays, energy recovery of waste plastic is typically conducted by combustion in incinerators or cement kilns. However, due to various types of waste plastics, their thermochemical behaviour has been rarely investigated. Even more, the thermochemical behaviour of waste plastics under oxy-combustion conditions has even rarely been studied. In this study non-isothermal thermogravimetric analyser was used to study the thermochemical behaviour of polyurethane plastic waste under seven different atmospheric conditions. Polyurethane decomposition kinetic constants have been estimated by the simultaneous evaluations of seven weight loss curves measured for the heating rate of 20 K/min and a final temperature of 1,073 K. The obtained results showed that the combustion of polyurethane is mainly composed of two stages, and the higher oxygen concentration slightly influenced the first stage but highly accelerates the second one, ascribing to a higher mean weight loss rate and an increasing activation energy. Replacing carbon dioxide with nitrogen slightly influences the first stage while positively influences the second stage, expressing in lower peak temperatures in differential thermogravimetry curves and higher peak values in differential scanning calorimetry curves.

Sustainability has become a broad societal goal, aiming to ensure that human beings coexist safely and harmoniously with nature over a longer time. The influence of the COVID-19 pandemic on the global economy is coming to an end. The development and merits of sustainable energy supply, advanced technology, and economic features have received significant attention over the last few decades. However, significant gaps still exist with respect to how to design, construct, and implement hybrid and optimal energy systems with the lowest investment and cost. Since 2002, the Sustainable Development of Energy, Water, and Environment Systems (SDEWES) conferences have become a significant meeting venue for researchers to introduce, discuss, share, and disseminate novel concepts and ideas. This paper presents an overview of published articles in the Special Issues (SIs) dedicated by the series SDEWES conferences, especially those published in Energies recommended by the 16th SDEWES Conference, which was held on 10–15 October 2021 in Dubrovnik, Croatia. This SI in Energies focused on four main topics, including the application of renewable bioenergy, component enhancement in renewable systems, sustainable development for buildings and economic analysis and evaluation for sustainability. The collected papers provide insight into the topics related to recent advances in improving sustainable efficiency, including studies on waste-to-wealth techniques, utilization of hybrid bioenergy systems, heat exchangers and other components for performance enhancement, energy supply and demand analysis, low-temperature DHC systems, techno-economic assessment, and environmental evaluation.

Anthropogenically caused climate change is amongst the main problems that society faces today. To limit the increase in average global surface temperature, several countries have developed targets (e.g., goals of the Paris agreement) that seek to reduce their greenhouse gas emissions levels, particularly from the energy and transport sectors. The installation of large renewable generating capacities creates new challenges. Particularly, their high variability creates uncertainties to the energy system regulators and operators to guarantee the security of supply at affordable prices. Therefore, new approaches must be considered to help reduce the uncetainty associated with variable renewable energy. Power-to-X and demand response technologies, which provide a high degree of flexibility to energy systems, could be in fact a viable solution.This research compares two methods of planning the development of energy system. The developed software H2RES is being compared to the existing commercial energy system's configuration optimization program PLEXOS. The research compares these models in terms of endogenous capacity expansion of renewable sources and flexibility options Additionally, H2RES is extended to account for endogenous capacity investment decisions in power and energy storage technologies. The two models are compared on the case of the Croatian Energy system. Results show that Power-to-X technologies provide the required flexibility in order to successfully integrate new generating capacities of variable renewable sources, reaching economically optimal and low carbon energy systems. Newly developed software H2RES is shown to be capable in providing energy system simulations, optimization and investment planning. Displayed functionalities in some aspects have shown to be even more capable than in established software PLEXOS to which it is compared. There is as well high amount of room for improvements due to its open-source nature.

The COVID-19 pandemic has had a significant impact on the supply chains of traditional fossil fuels. According to a report by the International Energy Agency (IEA) from 2020, oil-refining activity fell by more than the IEA had anticipated. It was also assumed that the demand in 2021 would likely be 2.6 million bpd below the 2019 levels. However, renewable markets have shown strong resilience during the crisis. It was determined that renewables are on track to meet 80% of the growth in electricity demand over the next 10 years and that sustainable energy will act as the primary source of electricity production instead of coal. On the other hand, the report also emphasized that measures for reducing environmental pollution and CO2 emissions are still insufficient and that significant current investments should be further expanded. The Sustainable Development of Energy, Water and Environment Systems (SDEWES) conference series is dedicated to the advancement and dissemination of knowledge on methods, policies and technologies for improving the sustainability of development by decoupling growth from the use of natural resources. The 15th SDEWES conference was held online from 1–5 September 2020; more than 300 reports with 7 special sections were organized on the virtual conference platform. This paper presents the major achievements of the recommended papers in the Special Issue of Energies. Additionally, related studies connected to the above papers published in the SDEWES series are also introduced, including the four main research fields of energy saving and emission reduction, renewable energy applications, the development of district heating systems, and the economic assessment of sustainable energy.

District heating systems are almost always located in densely populated urban areas where various heat sources are available, such as cooling and refrigeration systems in supermarkets, shopping malls, and power transformers. These urban sources often have a large share of waste heat, which is usually emitted into the environment. This waste heat could be used to partially cover the thermal load in district heating systems. The biggest challenge for their integration is the spatial distribution of urban heat sources in relation to the existing heat network and the temporal distribution of the availability of waste heat energy throughout the year. In this paper, we have developed an economic assessment model for the integration of urban heat sources into existing district heating systems. By the hourly merit order of waste heat utilization technologies based on pinch analysis, we have defined the most suitable integration of urban heat sources into existing district heating systems. Different temperature regimes of the urban source and the existing heat network have been considered. Finally, the method was tested on the case study of a supermarket and power substation located in Zagreb, while the sensitivity analysis was carried out with a focus on various technical and economic boundary conditions.

Crop-based biogas energy production, in combination with electricity generation under subsidy schemes, is no longer considered a favourable business model for biogas plants. Switching to low-cost or gate fee feedstocks and utilising biogas via alternative pathways could contribute to making existing plants fit for future operations and could open up new space for further expansion of the biogas sector. The aim of this study was to combine a holistic and interdisciplinary approach for both the biogas production side and the utilisation side to evaluate the impact of integrating the biogas sector with waste management systems and energy systems operating with a high share of renewable energy sources. The geospatial availability of residue materials from agriculture, industry and municipalities was assessed using QGIS software for the case of Northern Croatia with the goal of replacing maize silage in the operation of existing biogas plants. Furthermore, the analysis included positioning new biogas plants, which would produce renewable gas. The overall approach was evaluated through life cycle assessment using SimaPro software to quantify the environmental benefits and identify the bottlenecks of the implemented actions. The results showed that the given feedstocks could replace 212 GWh of biogas from maize silage in the relevant region and create an additional 191 GWh of biomethane in new plants. The LCA revealed that the proposed measures would contribute to the decarbonisation of natural gas by creating environmental benefits that are 36 times greater compared to a business-as-usual concept. The presented approach could be of interest to stakeholders in the biogas sector anywhere in the world to encourage further integration of biogas technologies into energy and environmental transitions.

The problem of modernization of the heat module (HM) with two-stage mixing scheme connection of hot water supply (HWS) by installations of the heat pump (HP) during interheating period is considered. Heating water of the in-house circuit of the building heating system is used as heat source for HP. The district cooling of the residential areas is possible through heaters during summer. R600 refrigerant is chosen for HP as a most environmentally freindly and as one that has low-pressure evaporation and condensation. The economic calculation is made for interheating period with and without HP. This paper advanes selection of optimum amount heat to be recovered during low potential heat utilisation and targets for heating and cooling capacities. Almost all residential buildings connected to the district heating and that have heat module with two-stage mixing scheme HWS system have market potential. Climatic conditions for such modernization are quite broad and include virtually all residential buildings in Europe. Primary energy consumption is taking place during daytime, when the cost is high. And so promising direction of development of the proposed approach to use HP in the in the heating system with hot water supply tanks, which charged at night. The results of this work may be used for in Total Site methodology development allowing heat recovery for district heating needs of both new designs and as retrofits to existing sites to ensure fast, widespread and cost-efficient industrial deployment. It leads to carbon footprint reduction and energy efficiency improvement of regions with heating and cooling demands during winter and summer seasons.

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.

Hybridisation of district heating systems can contribute to more efficient heat generation through cogeneration power plants or through the share increase of renewable energy sources in total energy consumption while reducing negative aspects of particular energy source utilisation. In this work, the performance of a hybrid district energy system for a small town in Croatia has been analysed. Mathematical model for process analysis and optimisation algorithm for optimal system configuration has been developed and described. The main goal of the system optimisation is to reduce heat production costs. Several energy sources for heat production have been considered in 8 different simulation cases. Simulation results show that the heat production costs could be reduced with introduction of different energy systems into an existing district heating system. Renewable energy based district heating systems could contribute to heat production costs decrease in district heating systems up to 30% in comparison with highly efficient heat production technologies based on conventional fuels.

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.

EU energy policy is more and more promoting a resilient, efficient and sustainable energy system. Several agreements have been signed in the last few months that set ambitious goals in terms of energy efficiency and emission reductions and to reduce the energy consumption in buildings. These actions are expected to fulfill the goals negotiated at the Paris Agreement in 2015. The successful development of this ambitious energy policy needs to be supported by scientific knowledge: a huge effort must be made in order to develop more efficient energy conversion technologies based both on renewables and fossil fuels. Similarly, researchers are also expected to work on the integration of conventional and novel systems, also taking into account the needs for the management of the novel energy systems in terms of energy storage and devices management. Therefore, a multi-disciplinary approach is required in order to achieve these goals. To ensure that the scientists belonging to the different disciplines are aware of the scientific progress in the other research areas, specific Conferences are periodically organized. One of the most popular conferences in this area is the Sustainable Development of Energy, Water and Environment Systems (SDEWES) Series Conference. The 12th Sustainable Development of Energy, Water and Environment Systems Conference was recently held in Dubrovnik, Croatia. The present Special Issue of Energies, specifically dedicated to the 12th SDEWES Conference, is focused on five main fields: energy policy and energy efficiency in smart energy systems, polygeneration and district heating, advanced combustion techniques and fuels, biomass and building efficiency.

District heating plays a key role in achieving high primary energy savings and the reduction of the overall environmental impact of the energy sector. This was recently recognized by the European Commission, which emphasizes the importance of these systems, especially when integrated with renewable energy sources, like solar, biomass, geothermal, etc. On the other hand, high amounts of heat are currently being wasted in the industry sector, which causes low energy efficiency of these processes. This excess heat can be utilized and transported to the final customer by a distribution network. The main goal of this research was to calculate the potential for excess heat utilization in district heating systems by implementing the levelized cost of excess heat method. Additionally, this paper proves the economic and environmental benefits of switching from individual heating solutions to a district heating system. This was done by using the QGIS software. The variation of different relevant parameters was taken into account in the sensitivity analysis. Therefore, the final result was the determination of the maximum potential distance of the excess heat source from the demand, for different available heat supplies, costs of pipes, and excess heat prices.

The Journal of Sustainable Development of Energy, Water and Environment Systems - JSDEWES is an international journal dedicated to the improvement and dissemination of knowledge on methods, policies and technologies for increasing the sustainability of development by de-coupling growth from natural resources and replacing them with knowledge based economy, taking into account its economic, environmental and social pillars, as well as methods for assessing and measuring sustainability of development, regarding energy, transport, water, environment and food production systems and their many combinations. In total 32 manuscripts were published in Volume IV, all of them reviewed by at least two reviewers. The Journal of Sustainable Development of Energy, Water and Environment Systems would like to thank reviewers for their contribution to the quality of the published manuscripts.

The Journal of Sustainable Development of Energy, Water and Environment Systems - JSDEWES is an international journal dedicated to the improvement and dissemination of knowledge on methods, policies and technologies for increasing the sustainability of development by de-coupling growth from natural resources and replacing them with knowledge based economy, taking into account its economic, environmental and social pillars, as well as methods for assessing and measuring sustainability of development, regarding energy, transport, water, environment and food production systems and their many combinations. In total 32 manuscripts were published in Volume III, all of them reviewed by at least two reviewers. The Journal of Sustainable Development of Energy, Water and Environment Systems would like to thank reviewers for their contribution to the quality of the published manuscripts.

The Journal of Sustainable Development of Energy, Water and Environment Systems – JSDEWES is an international journal dedicated to the improvement and dissemination of knowledge on methods, policies and technologies for increasing the sustainability of development by de-coupling growth from natural resources and replacing them with knowledge based economy, taking into account its economic, environmental and social pillars, as well as methods for assessing and measuring sustainability of development, regarding energy, transport, water, environment and food production systems and their many combinations. In total 32 manuscripts were published in Volume II, all of them reviewed by at least two reviewers. The Journal of Sustainable Development of Energy, Water and Environment Systems would like to thank reviewers for their contribution to the quality of the published manuscripts.

The Journal of Sustainable Development of Energy, Water and Environment Systems – JSDEWES is an international journal dedicated to the improvement and dissemination of knowledge on methods, policies and technologies for increasing the sustainability of development by de-coupling growth from natural resources and replacing them with knowledge based economy, taking into account its economic, environmental and social pillars, as well as methods for assessing and measuring sustainability of development, regarding energy, transport, water, environment and food production systems and their many combinations. In total 28 manuscripts were published in Volume I, all of them reviewed by at least two reviewers. The Journal of Sustainable Development of Energy, Water and Environment Systems would like to thank reviewers for their contribution to the quality of the published manuscripts.

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.