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Selected Papers from the SDEWES 2021 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 (1 March 2022) | Viewed by 42078

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Special Issue Editors

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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Prof. Dr. Neven Duić

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Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Lučićeva 5, HR-10000 Zagreb, Croatia
Interests: energy planning of energy systems with a high penetration of renewables; sustainable communities; energy policy; energy economics; mitigation of climate change; energy efficiency and combustion engineering
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Prof. Dr. Maria da Graça Carvalho

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Mechanical Engineering Department, University of Lisbon, 1649-004 Lisboa, Portugal
Interests: energy; sustainable development; climate change; energy policy; science-based policy making
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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. 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,

One of the main issues of the coming decades is improving efficiencies by integrating various life-supporting systems and using waste from one as resource in other and at the exact moment when it is beneficial to all, integrating electricity, heating, cooling, transport, water, buildings, waste, wastewater, industry, forestry, and agriculture systems. Sustainability also being a perfect field for interdisciplinary and multicultural evaluation of complex system, the SDEWES Conferences have become a significant venue for researchers in those areas to meet, and develop, discuss, share, and disseminate new ideas.

Energy has been and is the key factor in human development; however, it is also one of the main—if not the main—human environmental fingerprints. Even with a significant attention on the importance and merits of sustainable energy supply over the last few decades, there are still significant gaps to be filled with respect to how to design and implement technically optimal energy systems at the lowest costs.

This SI aims to provide an important contribution by presenting the state of the art with sustainable energy supply solutions ranging from the technical analyses of energy components on both the supply and demand side to energy scenarios and pathways. This Special Issue particularly welcomes SDEWES papers that address the energy system without traditional sector boundaries between electricity, heating, cooling, transportation, and industrial demands and rather consider the integration and synergies between these sectors.

The 16th conference on Sustainable Development of Energy, Water and Environment Systems—SDEWES Conference will be held in Dubrovnik, dedicated to the improvement and dissemination of knowledge on methods, policies, and technologies for increasing the sustainability of development by decoupling growth from natural resources and replacing them with a knowledge-based economy, taking into account its economic, environmental, and social pillars.

Prof. Dr. Francesco Calise
Prof. Dr. Neven Duić
Prof. Dr. Maria da Graça Carvalho
Prof. Dr. Qiuwang Wang
Prof. Dr. Poul Alberg Alberg Østergaard
Guest Editors

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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 100 words) can be sent to the Editorial Office for announcement on this website.

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

sustainability comparisons and measurements
smart energy systems
energy policy
water–energy nexus
energy system analysis
renewable energy resources
primary energy resources
renewable electricity generation systems
thermal power plants
district heating and/or cooling
advanced sustainable energy conversion systems
renewable heat systems
biofuels and biorefineries
alternative fuels
hybrid and electric vehicles
water treatment for drinking water
modeling for pollution avoidance and energy efficiency
cogeneration, trigeneration, polygeneration
energy storage
electricity transmission and distribution
gas security of supply
energy efficiency in industry and mining
energy efficient appliances
energy efficiency in buildings
energy markets

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24 pages, 3789 KiB

Open AccessReview

Recent Advances in Technologies, Methods, and Economic Analysis for Sustainable Development of Energy, Water, and Environment Systems

by Wenxiao Chu, Maria Vicidomini, Francesco Calise, Neven Duić, Poul Alborg Østergaard, Qiuwang Wang and Maria da Graça Carvalho

Energies 2022, 15(19), 7129; https://doi.org/10.3390/en15197129 - 28 Sep 2022

Cited by 13 | Viewed by 2599

Abstract

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. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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13 pages, 4146 KiB

Open AccessArticle

Direct Driven Hydraulic System for Skidders

by Juraj Benić, Juraj Karlušić, Željko Šitum, Mihael Cipek and Danijel Pavković

Energies 2022, 15(7), 2321; https://doi.org/10.3390/en15072321 - 23 Mar 2022

Cited by 6 | Viewed by 2768

Abstract

This paper investigates potential uses of a novel direct driven electro-hydraulic systems for articulated forestry tractors (skidders), due to these systems having notably higher energy efficiencies compared to classical electro-hydraulic systems that are currently being used in skidders for steering, lifting the front and the rear plate, as well as for operating the double-drum winch. A detailed analysis of the skidder rear plate mechanism is carried out, and static force profiles of hydraulic cylinders are obtained for the rear plate based on mechanism dynamics and measurement data from the literature. Thus, obtained results have been used to emulate the real-life force profiles in laboratory experiments featuring both the classical and the proposed direct driven hydraulic systems for the purpose of comparative analysis of their energy and fuel efficiency. These results are subsequently used to estimate the skidder fuel consumption and possible fuel savings over the entire vehicle life span for the realistic vehicle utilisation scenario. The main result is that fuel consumption can be reduced up to five times in the case of direct driven hydraulic system, thus effectively resulting in return of investment period of about four years in the case of skidder being retrofitted with direct driven hydraulic system. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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15 pages, 5132 KiB

Open AccessArticle

A Techno-Economic Analysis of Energy Storage Components of Microgrids for Improving Energy Management Strategies

by Alla Ndiaye, Fabrice Locment, Alexandre De Bernardinis, Manuela Sechilariu and Eduardo Redondo-Iglesias

Energies 2022, 15(4), 1556; https://doi.org/10.3390/en15041556 - 20 Feb 2022

Cited by 10 | Viewed by 2964

Abstract

Microgrids are essential elements of the energy transition because they allow optimal use of renewable energy sources (photovoltaic panels, wind turbines) and storage devices (batteries, supercapacitors) by connecting them to consumption poles (e.g., buildings, charging stations of electric vehicles). Lithium-ion batteries and supercapacitors are the main electrical storage devices usually used by microgrids for energy and power transient management. In the present paper, microgrid simulations have been performed. Electrothermal and aging models of storage components are presented. Strategies and scenarios for the batteries are presented either based on the state of charge limitation or hybrid association with supercapacitors. The contribution of this study is to provide a management strategy which considers the aging of storage systems in the real-time management of the microgrid in order to extend their life, while minimizing installation costs. The first approach for a techno-economic study provided in that study enables us to improve the strategies by optimizing the use of the battery. The results obtained in this paper demonstrate the key role of the techno-economic approach and knowledge of the aging processes of storage devices in improving the energy management and global feedback costs of microgrids. The simulation results show that battery life can be improved by 2.2 years. The improvement in battery life leads to a reduction in the total cost of the installation by reducing the cost of the batteries. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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17 pages, 2505 KiB

Open AccessArticle

Cost Optimized Building Energy Retrofit Measures and Primary Energy Savings under Different Retrofitting Materials, Economic Scenarios, and Energy Supply

by Leif Gustavsson and Chiara Piccardo

Energies 2022, 15(3), 1009; https://doi.org/10.3390/en15031009 - 29 Jan 2022

Cited by 16 | Viewed by 3370

Abstract

We analyze conventional retrofit building materials, aluminum, rock, and glass wool materials and compared such materials with wood-based materials to understand the lifecycle primary energy implications of moving from non-renewable to wood-based materials. We calculate cost optimum retrofit measures for a multi-apartment building in a lifecycle perspective, and lifecycle primary energy savings of each optimized measure. The retrofit measures consist of the thermal improvement of windows with varied frame materials, as well as extra insulation of attic floor, basement walls, and external walls with varied insulation materials. The most renewable-based heat supply is from a bioenergy-based district heating (DH) system. We use the marginal cost difference method to calculate cost-optimized retrofit measures. The net present value of energy cost savings of each measure with a varied energy performance is calculated and then compared with the calculated retrofit cost to identify the cost optimum of each measure. In a sensitivity analysis, we analyze the cost optimum retrofit measures under different economic and DH supply scenarios. The retrofit costs and primary energy savings vary somewhat between non-renewable and wood-based retrofit measures but do not influence the cost optimum levels significantly, as the economic parameters do. The lifecycle primary use of wood fiber insulation is about 76% and 80% less than for glass wool and rock wool, respectively. A small-scale DH system gives higher primary energy and cost savings compared to larger DH systems. The optimum final energy savings, in one of the economic scenarios, are close to meeting the requirements in one of the Swedish passive house standards. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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20 pages, 8799 KiB

Open AccessArticle

Complex Fluid Flow in Microchannels and Heat Pipes with Enhanced Surfaces for Advanced Heat Conversion and Recovery Systems

by Ana Sofia Moita, Pedro Pontes, Lourenço Martins, Miguel Coelho, Oscar Carvalho, F. P. Brito and António Luís N. Moreira

Energies 2022, 15(4), 1478; https://doi.org/10.3390/en15041478 - 17 Feb 2022

Cited by 8 | Viewed by 2162

Abstract

This paper addresses a multiscale approach for heat recovery systems, used in two distinct applications. In both applications, a microscale approach is used (microchannel heat sinks and heat pipes) for macroscale applications (cooling of a photovoltaic—PV cell), and the thermal energy of exhaust gases of an internal combustion engine is used for thermoelectric generators with variable conductance heat pipes. Several experimental techniques are combined such as visualization, thermography with high spatial and temporal resolution, and the characterization of the flow hydrodynamics, such as the friction losses. The analysis performed evidences the relevance of looking at the physics of the observed phenomena to optimize the heat sink geometry. For instance, the results based on the dissipated heat flux and the convective heat transfer coefficients obtained in the tests of the microchannel-based heat sinks for cooling applications in PV cells show an improvement in the dissipated power at the expense of controlled pumping power, for the best performing geometries. Simple geometries based on these results were then used as inputs in a genetic algorithm to produce the optimized geometries. In both applications, the analysis performed evidences the potential of using two-phase flows. However, instabilities at the microscale must be accurately addressed to take advantage of liquid phase change. In this context, the use of enhanced interfaces may significantly contribute to the resolution of the instability issues as they are able to control bubble dynamics. Such an approach is also addressed here. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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18 pages, 2918 KiB

Open AccessArticle

Data-Driven Optimal Design of a CHP Plant for a Hospital Building: Highlights on the Role of Biogas and Energy Storages on the Performance

by Lorenzo Bartolucci, Stefano Cordiner, Emanuele De Maina and Vincenzo Mulone

Energies 2022, 15(3), 858; https://doi.org/10.3390/en15030858 - 25 Jan 2022

Cited by 5 | Viewed by 2807

Abstract

Combined heat and power (CHP) generation plants are an assessed valuable solution to significantly reduce primary energy consumption and carbon dioxide emissions. Nevertheless, the primary energy saving (PES) and CO₂ reduction potentials of this solution are strictly related to the accurate definition and management of thermal and electric loads. Data-driven analysis could represent a significant contribution for optimizing the CHP plant design and operation and then to fully deploy this potential. In this paper, the use of a bi-level optimization approach for the design of a CHP is applied to a real application (a large Italian hospital in Rome). Based on historical data of the hospital thermal and electric demand, clustering analysis is applied to identify a limited number of load patterns representative of the annual load. These selected patterns are then used as input data in the design procedure. A Mixed Integer Linear Programming coupled with a Genetic Algorithm is implemented to optimize the energy dispatch and size of the CHP plant, respectively, with the aim of maximizing the PES while minimizing total costs and carbon emissions. Finally, the effects of integrating biogas from the Anaerobic Digestion (AD) of the Spent Coffee Ground (SCG) and Energy Storage (ES) technologies are investigated. The results achieved provide a benchmark for the application of these technologies in this specific field, highlighting performances and benefits with respect to traditional approaches. The effective design of the CHP unit allows for achieving CO₂ reduction in the order of 10%, ensuring economic savings (up to 40%), when compared with a baseline configuration where no CHP is installed. Further environmental benefits can be achieved by means of the integration of AD and ES pushing the CO₂ savings up to 20%, still keeping the economical convenience of the capital investment. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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17 pages, 2687 KiB

Open AccessArticle

Supporting Local Authorities to Plan Energy Efficiency in Public Buildings: From Local Needs to Regional Planning

by María Herrando, Antonio Gómez and Norberto Fueyo

Energies 2022, 15(3), 907; https://doi.org/10.3390/en15030907 - 27 Jan 2022

Cited by 11 | Viewed by 2142

Abstract

The support offered to local authorities in this work consisted of technical and economic training on the integration of energy efficiency measures as well as the development of tools (guidelines, a decision support tool, databases and a visualization platform) that allow local authorities to prepare their building renovation plans. These tools are found very useful for local authorities, particularly in the case of Teruel province, characterised by many small municipalities whose local governments do not have the technical staff to undertake this type of planning. As a result of this work, an energy action plan was elaborated for the implementation of 96 energy efficiency measures in public buildings of Teruel province. The execution of this plan would allow energy savings of 1.3 MWh/year and 245 tonsCO_2e/year of CO₂ emission reduction, involving an investment of EUR 1.2 M. The close collaboration with public authorities made it possible to assess the strengths and weaknesses of using the developed tools. One of the barriers found is the availability of accurate building data (e.g., regarding envelope features) necessary for the decision support tool. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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22 pages, 6344 KiB

Open AccessArticle

Passive Strategies for Building Retrofitting: Performances Analysis and Incentive Policies for the Iranian Scenario

by Yorgos Spanodimitriou, Giovanni Ciampi, Michelangelo Scorpio, Niloufar Mokhtari, Ainoor Teimoorzadeh, Roberta Laffi and Sergio Sibilio

Energies 2022, 15(5), 1628; https://doi.org/10.3390/en15051628 - 22 Feb 2022

Cited by 10 | Viewed by 3356

Abstract

A large amount of the Iranian energy demand is related to the building sector, mainly due to its obsolescence. In this paper, a second-skin system has been implemented as a retrofit action for an office building, evaluating the effect of a tensile material as second-skin in terms of primary energy saving, carbon dioxide equivalent emissions, and simple payback period. The analysis was carried out through numerical simulations across a whole year and for four Iranian cities (Tabriz, Teheran, Yazd, and Bandar Abbas) in four different climates (cold, temperate, hot-dry, and hot-wet), and with the building aligned at either north-south or east-west. Moreover, an economic analysis was carried out suggesting different incentive policies to promote building energy refurbishment. The simulation results highlighted a favorable orientation for buildings in Iran, suggesting a guideline for new constructions. Indeed, the best results were achieved for an east-west orientation of the building (up to a primary energy saving of 13.6% and reduction of carbon dioxide equivalent emissions of 45.5 Mg_CO₂,eq, in Yazd), with a decrease of the annual specific total (cooling and thermal) energy demand of 37.9 kWh/m²/year. The simple payback period values were also lower in the east-west orientation than the north-south one. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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22 pages, 28902 KiB

Open AccessArticle

Energy Analysis of an Industrial Nozzle with Variable Outlet Conditions during Compressible and Transient Airflow

by Krzysztof J. Wołosz

Energies 2022, 15(3), 841; https://doi.org/10.3390/en15030841 - 24 Jan 2022

Cited by 2 | Viewed by 2360

Abstract

The nozzle which is applied in industrial pneumatic pulsators is studied. It is a part of the system for unclogging the drains and outlets of silos and hoppers for loose materials. The nozzle is required to achieve the lowest level of energy losses while directing the airflow, which impacts the loose material bed. The energy rate transferred into the bed depends on the temperature and pressure differences between the inlet and outlet of the nozzle. In this study, the available energy is determined assuming compressible and transient airflow through the nozzle, which is a part of the industrial pneumatic pulsator. Numerical simulations are performed using the OpenFOAM CFD toolbox. Energy analysis is carried out by using Reynolds Transport Theorem for specific energy for the variable temperature inside the silo on the basis of CFD results. In fact, the air parameters at the outlet of the nozzle are the ones inside the silo. The study showed that the design of the nozzle is not very sufficient from an energetic point of view. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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11 pages, 2760 KiB

Open AccessArticle

Effect of Cooking Conditions on Selected Properties of Biodiesel Produced from Palm-Based Waste Cooking Oils

by Vladimir Plata, Deyanira Ferreira-Beltrán and Paola Gauthier-Maradei

Energies 2022, 15(3), 908; https://doi.org/10.3390/en15030908 - 27 Jan 2022

Cited by 8 | Viewed by 2217

Abstract

Cooking conditions affect oil properties and consequently, the quality of the derived biodiesel. Nevertheless, little information regarding the impact of the cooking process on biodiesel properties is currently available, especially for palm biodiesel. Therefore, this study examined the effect of cooking temperature, time of use, and length of reuse, on selected properties of biodiesel produced from palm-based waste cooking oils (WCO). Several WCO collected from restaurants belonging to four categories, namely fried chicken restaurants, fast food restaurants, snack producers, and typical restaurants, were subjected to base-catalyzed transesterification. The biodiesel yield was calculated, and the produced biodiesel was characterized as to its kinematic viscosity, calorific value, and cetane number. As a result, palm-based WCO performed better than other WCO in terms of biodiesel yield regardless of the conditions that they experienced, achieving almost 95% in some cases. The yield decreased as the cooking temperature and length of reuse moved upward, whereas the kinematic viscosity was sensitive only to the length of reuse, rising with increasing reuse. Non-compliance with biodiesel standards and technical requirements was observed in a few cases. The calorific value did not significantly change unless the cooking conditions were severe. The cetane number dropped as use and reuse decreased, remaining better compared to petrodiesel (70.2 ± 3.2 on average). Typical restaurants would generate the most suitable WCO to produce biodiesel, i.e., yield: 93.1 ± 0.2%; kinematic viscosity: 5.0 ± 0.3 mm²/s; calorific value: 39.9 ± 0.1 MJ/kg; density: 919 ± 9 kg/m³; and cetane number: 67.4 on average. This is consistent with the less severe cooking conditions employed at these restaurants. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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16 pages, 2256 KiB

Open AccessArticle

Investigation on Individual and Collective PV Self-Consumption for a Fifth Generation District Heating Network

by Jacopo Vivian, Mattia Chinello, Angelo Zarrella and Michele De Carli

Energies 2022, 15(3), 1022; https://doi.org/10.3390/en15031022 - 29 Jan 2022

Cited by 25 | Viewed by 3072

Abstract

Renewable Energy Communities have been recently introduced in European legislation to promote distributed generation from renewable energy sources. In fact, they allow to produce and consume energy from shared local power plants. Low temperature district heating and cooling networks with distributed heat pumps have demonstrated their capability to exploit renewable and waste heat sources in the urban environment. Therefore, they are considered a promising infrastructure to help decarbonize the building sector. As their main operating cost is the electricity purchased by the utility for heat pumps and circulation pumps, this work investigates whether a Renewable Energy Community could help mitigate such cost by sharing electricity produced by local photovoltaic (PV) systems. The research relies on computer simulations performed with both physical and statistical models for the evaluation of electrical load profiles at the district level. Results show that due to the different seasonality between heating demand and PV production, the increase in self-consumption due to the distributed heat pumps is lower than 10%. The use of batteries does not seem convenient for the same reason. The environmental benefit of the proposed system is evident, with CO₂ emissions reduced by 72–80% compared to the current situation depending on PV power installed. It also emerged that PV sharing significantly improves the self-consumption at the district level, in particular when the installed PV power is limited (+45%). In conclusion, results suggest that current incentives on PV-sharing make Renewable Energy Communities a viable option to improve the techno-economic performance of fifth-generation district heating and cooling networks. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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28 pages, 75361 KiB

Open AccessArticle

Statistical Investigation of Climate Change Effects on the Utilization of the Sediment Heat Energy

by Nebiyu Girgibo, Anne Mäkiranta, Xiaoshu Lü and Erkki Hiltunen

Energies 2022, 15(2), 435; https://doi.org/10.3390/en15020435 - 7 Jan 2022

Cited by 5 | Viewed by 3142

Abstract

Suvilahti, a suburb of the city of Vaasa in western Finland, was the first area to use seabed sediment heat as the main source of heating for a high number of houses. Moreover, in the same area, a unique land uplift effect is ongoing. The aim of this paper is to solve the challenges and find opportunities caused by global warming by utilizing seabed sediment energy as a renewable heat source. Measurement data of water and air temperature were analyzed, and correlations were established for the sediment temperature data using Statistical Analysis System (SAS) Enterprise Guide 7.1. software. The analysis and provisional forecast based on the autoregression integrated moving average (ARIMA) model revealed that air and water temperatures show incremental increases through time, and that sediment temperature has positive correlations with water temperature with a 2-month lag. Therefore, sediment heat energy is also expected to increase in the future. Factor analysis validations show that the data have a normal cluster and no particular outliers. This study concludes that sediment heat energy can be considered in prominent renewable production, transforming climate change into a useful solution, at least in summertime. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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26 pages, 4840 KiB

Open AccessFeature PaperArticle

Feasibility Assessment of a Dual Intake-Port Scroll Expander Operating in an ORC-Based Power Unit

by Fabio Fatigati, Giammarco Di Giovine and Roberto Cipollone

Energies 2022, 15(3), 770; https://doi.org/10.3390/en15030770 - 21 Jan 2022

Cited by 10 | Viewed by 3494

Abstract

The main driver of research in the road transportation sector is almost certainly the development of technologies which allow for the reduction of CO₂ emissions from internal combustion engines (ICEs). Wasted heat recovery (WHR) from the exhaust gases of ICEs based on organic rankine cycle (ORC) power units is one of the most promising technological solutions. However, several issues are raised when the recovery unit is scaled down to small applications, not to mention the fact that thermal sources are characterized by their intrinsically transient nature, as is the case with ICEs. In fact, this leads the ORC unit having to work frequently in off-design conditions. To successfully overcome this issue, the proper design and selection of the expanders are crucial. They are generally chosen from volumetric-type machines, thanks to their capacity to deal with time-varying thermo-fluid dynamic inlet properties. Among them, scroll machines represent one of the best solutions, despite them not yet being optimized as expanders, with them having been studied more as compressors. Dual-intake-port (DIP) technology is a novel solution used to enhance the performance of scroll machines. The effectiveness of this technology was assessed thanks to a comprehensive, experimentally-validated theoretical model of the scroll. It demonstrated that DIP technology can produce a 25% increase in mechanical power with respect to the baseline machine, without modifying the in–out pressure ratio. Maintaining a constant pressure difference across the expander at 5.6 bar, the power grew from 1131 W to 1410 W with the adoption of DIP technology. This power boost is lower than that achieved with a comparable DIP sliding rotary vane expander (SVRE) already studied by the authors, but the DIP Scroll achieved a higher efficiency (50–60%) when compared to the DIP SVRE case (40%). Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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21 pages, 4348 KiB

Open AccessArticle

Modelling and Environmental Assessment of a Stand-Alone Micro-Grid System in a Mountain Hut Using Renewables

by Mitja Mori, Manuel Gutiérrez, Mihael Sekavčnik and Boštjan Drobnič

Energies 2022, 15(1), 202; https://doi.org/10.3390/en15010202 - 29 Dec 2021

Cited by 6 | Viewed by 2494

Abstract

Mountain huts are stand-alone micro-grid systems that are not connected to a power grid. However, they impact the environment by generating electricity and through day-to-day operations. The installed generator needs to be flexible to cover fluctuations in the energy demand. Replacing fossil fuels with renewable energy sources presents a challenge when it comes to balancing electricity generation and consumption. This paper presents an integration-and-optimization process for renewable energy sources in a mountain hut’s electricity generation system combined with a lifecycle assessment. A custom computational model was developed, validated with experimental data and integrated into a TRNSYS model. Five different electricity generation topologies were modelled to find the best configuration that matches the dynamics and meets the cumulative electricity demand. A lifecycle assessment methodology was used to evaluate the environmental impacts of all the topologies for one typical operating year. The carbon footprint could be reduced by 34% in the case of the actually implemented system upgrade, and by up to 47% in the case of 100% renewable electricity generation. An investment cost analysis shows that improving the battery charging strategy has a minor effect on the payback time, but it can significantly reduce the environmental impacts. Full article

(This article belongs to the Special Issue Selected Papers from the SDEWES 2021 Conference on Sustainable Development of Energy, Water and Environment Systems)

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