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Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems

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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A: Sustainable Energy".

Deadline for manuscript submissions: closed (31 March 2026) | Viewed by 7016

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Prof. Dr. Francesco Calise

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Department of Industrial Engineering, University of Naples Federico II, 80125 Naples, Italy
Interests: fuel cells; advanced optimization techniques; solar thermal systems; concentrating photovoltaic/thermal photovoltaic systems; energy saving in buildings; solar heating and cooling; organic Rankine cycles; geothermal energy; dynamic simulations of energy systems; renewable polygeneration systems
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Dr. Maria Vicidomini

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Department of Industrial Engineering, University of Naples Federico II, 80125 Naples, Italy
Interests: solar thermal systems; concentrating photovoltaic/thermal photovoltaic systems; energy saving in buildings; solar heating and cooling; solar desalination; geothermal energy; dynamic simulations of energy systems; renewable polygeneration systems
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Prof. Dr. Qiuwang Wang

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Key Laboratory of Thermo-Fluid Science and Engineering (Ministry of Education), Xi’an Jiaotong University, Xi’an 710049, China
Interests: heat transfer enhancement and its applications to engineering problems; high-temperature heat transfer and fluid flow; transport phenomena in porous media; numerical simulation; prediction and optimization
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Prof. Dr. Wenxiao Chu

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Key Laboratory of Thermo-Fluid Science and Engineering (Ministry of Education), Xi’an Jiaotong University, Xi’an 710049, China
Interests: energy systems; enhanced heat transfer; thermal management; heating, ventilating, and air conditioning (HVAC); supercritical fluid
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Prof. Dr. Poul Alberg Østergaard

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Department of Planning, Aalborg University, 9000 Aalborg, Denmark
Interests: energy systems; energy scenarios; renewable energy system integration; energy and development; environmental impacts from energy development
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Special Issue Information

Dear Colleagues,

In recent decades, the integration and enhancement of energy efficiency across multiple sectors—including electricity, heating, cooling, transport, water, buildings, industry, waste, wastewater, forestry, and agriculture—have become increasingly crucial. In the context of a society striving for sustainability and the urgent need to mitigate greenhouse gas emissions, the SDEWES Conferences have established themselves as a key platform for researchers to exchange ideas, present innovations, and disseminate knowledge.

Within this framework, energy saving and emissions reduction are essential for reducing humanity’s environmental footprint. Despite considerable progress in promoting sustainable energy solutions, important challenges remain in designing and implementing technically optimal energy systems at minimal cost. Addressing these challenges requires attention to renewable energy resources for power and heat generation, advanced sustainable energy conversion and storage systems, hydrogen technologies, power-to-X approaches, and carbon capture, utilization and storage (CCUS) solutions.

This Special Issue aims to provide a comprehensive overview of state-of-the-art solutions for sustainable energy supply, spanning from technical analyses of energy components on both supply and demand sides to scenarios and pathways for decarbonization. Contributions are particularly welcome on topics including, but not limited to: energy efficiency in industry and buildings, smart energy systems, district heating and cooling, cogeneration, trigeneration, polygeneration, biofuels and alternative fuels, hybrid and electric vehicles, waste-to-energy, the biocircular economy, the water–energy–food nexus, electricity transmission and distribution, digitalization and AI applications for energy systems, energy storage and batteries, energy markets and policy, gas security of supply, climate change mitigation and adaptation strategies, decarbonization pathways, and resilience of energy infrastructure.

The 20th Conference on Sustainable Development of Energy, Water and Environment Systems—SDEWES Conference will be held on the 5–10 October 2025 in Dubrovnik (Croatia). The 1^st African SDEWES Conference was held on the 27–31 May 2025 in Oujda–Saidia (Morocco). These SDEWES Conferences are dedicated to the improvement and dissemination of knowledge concerning methods, policies, and technologies for increasing the sustainability of development by de-coupling growth from natural resources and replacing resource exploitation with a knowledge-based economy, taking into account economic, environmental, and social pillars.

We especially encourage submissions that explore integrated energy systems without traditional sector boundaries, highlighting synergies across electricity, heating, cooling, transport, and industrial demands.

Prof. Dr. Francesco Calise
Dr. Maria Vicidomini
Prof. Dr. Qiuwang Wang
Prof. Dr. Wenxiao Chu
Prof. Dr. Poul Alberg Østergaard
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

renewable energy resources
power and heat generation
advanced energy storage systems
power-to-X
hydrogen economy and technologies
carbon capture, utilization and storage (CCUS)
energy efficiency in industry and buildings
smart energy systems
district heating and/or cooling
cogeneration, trigeneration, polygeneration
biofuels and alternative fuels
hybrid and electric vehicles
waste-to-energy
biocircular economy
water–energy–food nexus
electricity transmission and distribution
digitalization and AI for energy systems
energy storage and batteries
energy markets
energy policy
gas security of supply
climate change mitigation strategies
decarbonization pathways
resilience of energy infrastructure

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Published Papers (8 papers)

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Research

32 pages, 3593 KB

Open AccessArticle

Hydrogen Combined Cycles for Low-Carbon Power and Long-Term Carbon Storage

by Julliana Muniz Gonçalves, Gustavo Brêtas Fernandes da Silva, Stefano Ferrari Interlenghi, Jeiveison Gobério Soares Santos Maia and Gustavo Bonolo de Campos

Energies 2026, 19(5), 1275; https://doi.org/10.3390/en19051275 - 4 Mar 2026

Viewed by 420

Abstract

This study presents a comprehensive sustainability assessment of power generation configurations integrating blue hydrogen combined cycles with different carbon capture technologies. Four scenarios were systematically evaluated through process simulation and multi-criteria decision analysis, encompassing technical, economic, environmental, and social indicators. The assessed configurations comprise a conventional natural gas combined cycle, representing the current carbon-based benchmark, alongside three innovative blue hydrogen combined-cycle pathways incorporating distinct carbon capture technologies. The results demonstrate pronounced trade-offs among the evaluated scenarios: although the conventional configuration exhibits superior economic performance, it presents the least favorable environmental outcome, with a carbon intensity approximately an order of magnitude higher than that of the hydrogen-based alternatives. In terms of electricity generation potential, hydrogen-fired combined cycles achieve comparable energy performance, delivering 0.103 kWh per kJ of hydrogen relative to 0.116 kWh per kJ of natural gas. For all evaluated configurations, the chemical absorption case achieved the highest overall sustainability performance, attaining a sustainability degree of 1.41, corresponding to a 25% improvement over the conventional process. The findings of the present work underscore the potential of integrating blue hydrogen combined cycles to substantially improve the sustainability of electricity generation while supporting decarbonization pathways within the energy sector. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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20 pages, 3241 KB

Open AccessArticle

A GIS-Based Approach to Identifying Suitable Areas for Positive Energy Districts Development

by Iván Ramos-Diez, Sofía Mulero-Palencia and José L. Hernández

Energies 2026, 19(4), 1030; https://doi.org/10.3390/en19041030 - 15 Feb 2026

Viewed by 563

Abstract

Positive Energy Districts (PEDs) have been proposed as a holistic approach to urban decarbonization. PEDs are defined as delimited areas that produce, annually, more energy than they consume. The methodology proposed for PED assessment integrates multicriteria decision-making geospatial analysis and weighted overlay techniques to assess PED suitability across different dimensions. Data harmonization is included as part of the modeling process, ensuring methodological consistency across diverse contexts. The approach employs a layer overlay and aggregation through a weighting average process, calibrated through stakeholder input, to reflect local priorities and urban-specific conditions in order to identify the potential areas for PED implementation. Geospatial datasets provided as inputs are processed to produce maps that reflect the PED suitability index for the city districts according to the selected dimensions. As a result, the open-source developed MCDA algorithm provides maps that facilitate the identification of relevant zones for PED feasibility. The algorithm was applied in Bratislava city, understanding its identification potential, adaptability and scalability to other cities. The obtained results highlight the most interesting districts in which to build a PED in Bratislava, promoting the algorithm as a replicable decision-making tool for advancing PED identification and deployment. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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22 pages, 3319 KB

Open AccessArticle

Study, Modelling and Computing of Pressure Losses in GH₂ Pipelines

by Akshay Bambore, Patrick Hendrick and Jean Philippe Ponthot

Energies 2026, 19(4), 885; https://doi.org/10.3390/en19040885 - 8 Feb 2026

Viewed by 474

Abstract

The Wallonia region of Belgium aims to transition to a modern hydrogen infrastructure. Given the relatively low density of hydrogen gas, it is important to understand its nature and behavior during transport through pipelines. This study aims to observe the pressure loss in pipelines due to surface roughness with H₂ and other singular losses to find a solution to minimize the amount of pressure loss that occurs during transportation. This study involves numerical methods and gas equation models to determine the pressure loss. This analysis includes the properties of hydrogen gas, the pipeline material used, the friction factor, pipeline efficiency, and other relevant properties of hydrogen and pipelines. To address this challenge, the study integrates numerical fluid dynamics methods with structural modelling of pipeline walls. It accounts for long-term friction effects, erosion over several years, radial pressure gradients (mixing pressure drop), acceleration effects, and gravity influences, considering the non-ideal behavior of gaseous hydrogen (GH2). This study provides a systematic comparison between AGA-based analytical models and CFD simulations using a scaled pipeline approach, enabling reliable estimation of pressure losses in long-distance hydrogen pipelines. The proposed methodology integrates scaling, numerical validation, and CFD simulation to compute pressure losses in a hydrogen pipeline. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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21 pages, 793 KB

Open AccessArticle

Assessing Energy and Waste Impacts in Orthopaedic Departments: A Case Study from an Italian Public Hospital

by Anna Savio, Beatrice Marchi, Andrea Roletto, Pierangelo Guizzi, Giuseppe Milano, Lucio Enrico Zavanella and Simone Zanoni

Energies 2026, 19(3), 836; https://doi.org/10.3390/en19030836 - 5 Feb 2026

Viewed by 607

Abstract

Hospitals are major consumers of natural resources, and their continuous 24/7 demands exert significant environmental repercussions. Notably, energy utilization and waste generation constitute primary determinants of the ecological footprint associated with healthcare facilities. This study aims to provide a replicable framework for estimating operational carbon account of orthopedic hospital operations using readily available data, without requiring expert-level life cycle assessment tools. A three-level analysis was applied to a case study in a large Italian public hospital, focusing on CO₂e emissions from energy consumption and hazardous waste generation. Operational data from the hospital and detailed audits of orthopedic procedures were used to estimate energy consumption, ventilation loads, and waste volumes. Results showed that HVAC systems dominated energy-related emissions, while surgical waste was a major contributor at the meso- and micro-levels. Several mitigation strategies were proposed, including reducing off-hours air exchange rates and improving waste segregation, leading to potential emission reductions. The study highlights that even a simplified carbon accounting approach can generate valuable insights for healthcare managers, supporting internal benchmarking and sustainability action. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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18 pages, 1471 KB

Open AccessArticle

Modelling, Simulation, and Experimental Validation of a Thermal Cabin Model of an Electric Minibus

by Thomas Bäuml, Irina Maric, Dominik Dvorak, Dragan Šimić and Johannes Konrad

Energies 2026, 19(3), 655; https://doi.org/10.3390/en19030655 - 27 Jan 2026

Viewed by 1733

Abstract

In response to the urgent need for decarbonising the transport sector, this paper analyses the thermal performance of a battery electric minibus under cold ambient conditions. Thermal simulation models of the vehicle cabin and its electric heating circuits for both driver and passenger areas were developed using Modelica and validated with measurement data at −7 °C and 0 °C. The model showed good agreement with the measurements, with cabin temperature deviations within ±1.6 K and heating power deviations below 6%. Results show that the existing electric-only heating system is, in the automatic heating mode selected, insufficient to reach the target cabin temperature of 23 °C, as the optional fuel-powered heater was omitted to ensure fully zero-emission operation. To address this, an extended heating system with an additional heat exchanger was implemented in the simulation, which improved the overall cabin temperature level and also its spatial variation. However, it also increased the heating power demand by 43% at −7 °C (from 4.8 kW to 6.8 kW) and by 17% at 0 °C (from 4.8 kW to 5.6 kW). An additional heat loss analysis revealed that approx. 65–75% of all thermal losses occur through the window areas. Future improvements should therefore focus on optimising the heating strategy and enhancing cabin and heating system insulation to reduce energy demand while maintaining or even improving passenger comfort. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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17 pages, 836 KB

Open AccessArticle

Simplifications in the Optimization of Heat Pumps and Their Comparison for Effects on the Accuracy of the Results

by Maurice Görgen, Louisa Zaubitzer and Frank Alsmeyer

Energies 2026, 19(3), 635; https://doi.org/10.3390/en19030635 - 26 Jan 2026

Viewed by 430

Abstract

This work presents a model that calculates temperature-dependent heat pump performances as a circular heat pump process as a reference model. The model is then systematically simplified by making assumptions or applying functional approximations to key variables. These simplifications include linearization of the substance database calculations and modeling of the compressor efficiency as a function or constant. The effects of these simplifications on the accuracy of results are quantified and compared with other modeling approaches from the literature suitable for linear and bilinear optimization issues. Initial comparisons show that the root mean square error of the model achieves better results than comparable methods. While the root mean square error of the COP in linearized models in the compared literature ranges from 0.433 to 1.233, it can be improved to a maximum of 0.335 using the approach presented. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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20 pages, 2736 KB

Open AccessArticle

Operational Optimization of Steam Turbine Systems for Time Series in Hourly Resolution: A Systematic Comparison of Linear, Quadratic and Nonlinear Approaches

by Louisa Zaubitzer, Maurice Görgen and Frank Alsmeyer

Energies 2026, 19(3), 589; https://doi.org/10.3390/en19030589 - 23 Jan 2026

Viewed by 529

Abstract

Computer-aided modeling and mathematical optimization of energy systems are essential for improving operational efficiency and achieving emission reductions, particularly for steam turbine systems with part-load-dependent efficiency characteristics. Mixed-Integer Linear Programming (MILP) is the state of the art, due to its short computational times and reliable convergence. However, its simplifications often reduce model accuracy. Mixed-Integer Nonlinear Programming (MINLP) offers high accuracy but faces long computational times and potential convergence issues. Recent advancements in Mixed-Integer Quadratically Constrained Programming (MIQCP) offer a promising approach for more accurate energy system modeling by enabling quadratic and bilinear representations while avoiding the full complexity of nonlinear programs. This study compares the optimization methods MILP, MINLP and MIQCP for the operational optimization of a steam turbine system. The parameterization of the models is based on hourly measurement data of two real-world steam turbines. Key evaluation criteria include accuracy, computational time, implementation complexity and the deviation in the calculated optimum. The results show that MIQCP improves accuracy compared with MILP while requiring lower computational time than MINLP. Overall, the results demonstrate that MIQCP provides a suitable compromise between model accuracy and computational efficiency for the operational optimization of steam turbine systems. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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16 pages, 2976 KB

Open AccessArticle

Performance Simulation of an Unglazed Transpired Solar Collector: Two-Dimensional and Three-Dimensional Analysis

by Giedrė Streckienė and Martin Piskulov

Energies 2026, 19(2), 481; https://doi.org/10.3390/en19020481 - 19 Jan 2026

Viewed by 660

Abstract

The growing depletion of fossil fuel resources and rising energy costs underscore the need for efficient renewable energy technologies, such as unglazed transpired solar collectors (UTSCs). UTSCs harness solar energy to preheat outdoor air, thereby improving building energy efficiency and reducing reliance on conventional heating systems. This study presents a computational fluid dynamics (CFD) analysis of UTSC performance under Lithuanian winter conditions (ambient air temperature −2.64 °C, solar irradiance 733.45 W/m², wind speed 1.93 m/s) using two- and three-dimensional models developed in ANSYS FLUENT. The 3D model simulates a realistic wall fragment with multiple repeating sheet metal profiles and an air gap, while the 2D model represents a longitudinal section applicable to generic UTSC configurations. Both models were validated against experimental data and used to evaluate airflow velocity, pressure distribution, and air temperature rise. The results indicate overall thermal efficiencies of 54.32% for the 3D model and 54.07% for the 2D model, demonstrating that simplified 2D models can achieve comparable accuracy while significantly reducing computational cost. These findings highlight the potential of high-resolution CFD modelling for optimizing UTSC design and enabling faster, more reliable assessments for integration in industrial and commercial building applications. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water, and Environment Systems)

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