| 1. |
- Abdallah, Mohammed, et al.
(författare)
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Daily global solar radiation time series prediction using variational mode decomposition combined with multi-functional recurrent fuzzy neural network and quantile regression forests algorithm
- 2023
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Ingår i: Energy Reports. - 2352-4847. ; 10, s. 4198-4217
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Tidskriftsartikel (refereegranskat)abstract
- Global solar radiation (GSR) prediction capability with a reliable model and high accuracy is crucial for comprehending hydrological and meteorological systems. It is vital for the production of renewable and clean energy. This research aims to evaluate the performance of combined variational mode decomposition (VMD) with a multi-functional recurrent fuzzy neural network (MFRFNN) and quantile regression forests (QRF) models for GSR prediction in daily scales. The hybrid VMD-MFRFNN and QRF models were compared with standalone MFRFNN, random forest (RF), extreme gradient boosting (XGB), and M5 tree (M5T) models across the Lund and Växjö meteorological stations in Sweden. The meteorological data from 2008 to 2017 were used to train the models, while the prediction accuracy was verified by using the data from 2018 to 2021 under five different input combinations. The various meteorological-based scenarios (including the input are air temperatures (Tmin, Tmax, T), wind speed (WS), relative humidity (RH), sunshine duration (SSH), and maximum possible sunshine duration (N)) were considered as input of predictor models. The current study resulted that the M5T model exhibited higher accuracy than RF and XGB models, while the QRF model showed equivalent performance with the M5T model at both study sites. The MFRFNN model outperformed QRF and M5T models across all input combinations at both study sites. The hybrid VMD-MFRFNN model showed the best performance when fewer input variables (Tmin, Tmax, T, WS at Lund station and Tmin, Tmax, T, WS, SSH, RH at Växjö station) were used for GSR prediction. We conclude that the MFRFNN model best predicts average daily GSR when combining all meteorological variables (Tmin, Tmax, T, WS, SSH, RH, N).
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| 2. |
- Abugabbara, Marwan, et al.
(författare)
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How to develop fifth-generation district heating and cooling in Sweden? : Application review and best practices proposed by middle agents
- 2023
-
Ingår i: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 9, s. 4971-4983
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Tidskriftsartikel (refereegranskat)abstract
- Sweden has an ambitious plan to fully decarbonise district heating by 2030 and to contribute with negative emissions of greenhouse gases in 2050. The vagaries of the energy market associated with climate, political, and social changes entail cross-sectoral integration that can fulfill these national targets. Fifth-generation district heating and cooling (5GDHC) is a relatively new concept of district energy systems that features a simultaneous supply of heating and cooling using power-to-heat technologies. This paper presents best practices for developing 5GDHC systems in Sweden to reach a consensus view on these systems among all stakeholders. A mixed-method combining best practice and roadmapping workshops has been used to disseminate mixed knowledge and experience from middle agents representing industry professionals and practitioners. Four successful implementations of 5GDHC systems are demonstrated and the important learned lessons are shared. The best practices are outlined for system planning, system modeling and simulation, prevailing business models for energy communities, and system monitoring. A roadmap from the middle agents’ point of view is composed and can be utilised to establish industry standards and common regulatory frameworks. © 2023 The Author(s)
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| 3. |
- Abugabbara, Marwan, et al.
(författare)
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Modelica-based simulations of decentralised substations to support decarbonisation of district heating and cooling
- 2021
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 7:4, s. 465-472
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Tidskriftsartikel (refereegranskat)abstract
- District heating and cooling are considered effective solutions to decarbonise the energy use in the building sector. The latest generation of district heating and cooling also increases the potential of integrating heat pumps and chillers in each building substation. The benefits of such integration are the reduction of network temperature and distribution losses; the recovery of waste heat through a bidirectional network; and the decentralised production of heating and cooling. Sizing the network depends mainly on the heat flows between connected buildings. The substation performance and technical installations determine these heat flows. We present in this paper Modelica-based simulations of two design cases for substations. The first design case involves installed heat pump, chiller, and circulation pumps. Alternatively, the second design enables the heat pump to provide direct cooling through a heat exchanger. The models for these installations were developed using the Modelica language to perform continuous-time simulations. The performance in each design case was evaluated in terms of seasonal coefficient of performance and total electric energy use. An analysis on a cluster of 11 buildings suggests that the addition of the direct cooling heat exchanger can save up to 10% of the total annual electric energy use. Additional savings can be achieved by optimising the building supply temperatures and the district network temperature.
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| 4. |
- Agar, David, et al.
(författare)
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Combining behavioural TOPSIS and six multi-criteria weighting methods to rank biomass fuel pellets for energy use in Sweden
- 2023
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Ingår i: Energy Reports. - 2352-4847. ; 10, s. 706-718
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Tidskriftsartikel (refereegranskat)abstract
- EU energy and climate policies continue to drive interest in biomass fuel pellets which can be produced from a wide variety of feedstock. The use of multi-criteria decision analysis (MCDA) to support feedstock selection has the potential for more transparent and better decision-making. This study applies the behavioural TOPSIS, a prominent MCDA technique, to rank pellets for energy use in Sweden produced from under-utilised forest and agricultural biomass. Seven criteria were used to assess and rank the biomass pellets. The alternatives include 88 types of pellets from 11 biomass materials. Possible attitudes of an expert towards the risk of losses (risk averse, risk neutral and risk-seeking) were combined with six sets of criteria weights obtained using six weighting methods – a total of 18 input settings (scenarios). Despite having different input settings, almost identical results were obtained in all scenarios, meaning that the rankings were stable and consistent. Across all 18 scenarios, pellets produced from a reference spruce/pine sawdust blend are ranked ahead of other pellet types. Pellets produced from Scots pine bark exhibited stable and consistent rankings across all scenarios; and thus this biomass is the second-best overall. The next best materials overall are poplar, reed canary grass and wheat straw, whereas torrefied pellets (torrefied beech, poplar and wheat straw) were ranked last in all scenarios. Combining behavioural TOPSIS and a variety of criteria-weighting methods is a meaningful way of improving decision-making with respect to producing a more valid and reliable ranking of biomass fuel pellets for energy use in Sweden.
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| 5. |
- Agyekum, Ephraim Bonah, et al.
(författare)
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Towards a reduction of emissions and cost-savings in homes: Techno-economic and environmental impact of two different solar water heaters
- 2024
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Ingår i: Energy Reports. - : ELSEVIER. - 2352-4847. ; 11, s. 963-981
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Tidskriftsartikel (refereegranskat)abstract
- South Africa currently has the highest carbon emission intensity per kilowatt of electricity generation globally, and its government intends to reduce it. Some of the measures taken by the government include a reduction of emissions in the building sector using solar water heating (SWH) systems. However, there is currently no study in the country that comprehensively assesses the technical, economic, and environmental impact of SWH systems across the country. This study therefore used the System Advisor Model (SAM) to model two different technologies of SWH systems (i.e., flat plate (FPC) and evacuated tube (EPC) SWH) at five different locations (i.e., Pretoria, Upington, Kimberley, Durban, and Cape Town) strategically selected across the country. According to the study, the optimum azimuth for both the evacuated tube and flat plate SWH system in South Africa is 0 degrees. Installing FPC and EPC at the different locations would yield payback periods of 3.2 to 4.4 years and 3.5 to 4.3 years, respectively. Comparably, levelized cost of energy for the FPC and EPC will range from 7.47 to 9.62 cents/kWh and 7.66 to 9.24 cents/kWh, respectively, based on where the SWH system is located. Depending on where the facility is located, the annual cost savings for the FPC system would be between $486 and $625, while the EPC system would save between $529 and $638. Using SWHs can reduce CO2 emissions by 75-77% for the evacuated tube system and 69-76% for the flat plate system annually, depending on the location.
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| 6. |
- Al-Sulttani, Ali Omran, et al.
(författare)
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Thermal effectiveness of solar collector using Graphene nanostructures suspended in ethylene glycol–water mixtures
- 2022
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 8, s. 1867-1882
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Tidskriftsartikel (refereegranskat)abstract
- Flat plate solar collectors (FPSCs) are the most often used as solar collectors due to their easiness of installation and usage. The current research investigates the energy efficiency of FPSC using different mass concentration with varied base fluids containing Graphene nanofluids (T-Gr). Mass concentration of 0.1%-wt., 0.075%-wt., 0.050%-wt. and 0.025%-wt. were mixed with ethylene glycol (EG) and distilled water (DW) in different rations. The operating conditions were volumetric flowrate (1.5, 1 and 0.5) LPM 50 °C-input fluid temperature and 800 W/m2-global solar irradiation. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) were used to synthesize the thermally treated nanomaterial. The theoretical investigation indicated that using T-Gr nanosuspensions increased the FPSC efficiency in comparison with the host fluid for all examined mass concentrations and volumetric flowrates. In quantitative terms, the maximum thermal effectiveness improvement for the EG, (DW:70 + EG:30) and DW:EG (DW:50 + EG:50) and using flowrates of (1.5, 1 and 0.5) LPM were 12.54%, 12.46% and 12.48%. In addition, the research results pointed that the essential parameters (i.e., loss energy (FRUL)) and gain energy (FR (τα)) of the T-Gr nanofluids were increased significantly.
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| 7. |
- Andersson, Elias, 1989-, et al.
(författare)
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Decarbonization of industry : Implementation of energy performance indicators for successful energy management practices in kraft pulp mills
- 2021
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 7, s. 1808-1817
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Tidskriftsartikel (refereegranskat)abstract
- Energy management is the most prominent means of improving energy efficiency, and improved energy efficiency constitutes the cornerstone in decarbonization. For successful industrial energy management, defining accurate energy performance indicators (EnPIs) is essential. Energy-intensive industries have previously been found to have an improvement potential regarding the current monitoring of EnPIs, especially at process level. While general models for developing and implementing EnPIs exist, manufacturing industries are diverse in terms of their production processes, which is why industry-tailored models for EnPI development are needed. One major outcome of this paper is a unique model specifically tailored for kraft pulp mills. The model derives from a practice-based approach for EnPI development, building on real-life experiences from a Swedish group of companies. This paper’s developed model, and the validation of the EnPIs, further increase the understanding of the kraft pulp industry’s processes and how to apply descriptive and explanatory indicators. The developed model can potentially be generalized to other sectors.
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| 8. |
- Andrei, Mariana, et al.
(författare)
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Decarbonization of industry : Guidelines towards a harmonized energy efficiency policy program impact evaluation methodology
- 2021
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 7, s. 1385-1395
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Tidskriftsartikel (refereegranskat)abstract
- The decarbonization of EU energy system is under way, but manufacturing industry is still using approximately 25% of the EU total final energy use. To maintain long-term competitiveness while contributing to the EU goal of carbon neutrality by 2050, manufacturing industry needs to improve energy efficiency in a cost-effective way. One important way to achieve this is through energy audits. The Energy Efficiency Directive promotes member states development of energy efficiency programs to encourage industry to undergo energy audits. Previous studies have reviewed industrial energy efficiency policy program evaluations and argued that there is no harmonized way to conduct them. This leads to difficulties in: i) comparing energy efficiency and cost saving potentials throughout different programs, and ii) providing necessary information that supports the improvement of the policy program. Therefore, we argue that a harmonized methodology for industrial energy efficiency policy program evaluation is of great importance, and, we have developed a set of five-steps guidelines that lay the foundation for an ex-ante energy efficiency policy program evaluation methodology. The guidelines are to be be conducted during the lifetime of the program, in five steps, as follows: (s1) define key issues, (s2) set the objectives for each key issue, (s3) identify the options for each key issue, (s4) analyze options from an energy and environmental perspective, and (s5) compare options and select the recommended one. Our proposed methodology will support policymakers and evaluators answer questions such as: i) how can the objectives of the policy program be achieved? ii) is there any need to change the policy program? Furthermore, a comparison in terms of relevance, efficiency, effectiveness, and sustainability of all major policy options developed, including the status quo option is proposed in the methodology. This paper can be seen an important step towards the goal of creating a harmonized policy evaluation methodology. (C) 2021 The Authors. Published by Elsevier Ltd.
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| 9. |
- Andrei, Mariana, 1981-, et al.
(författare)
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Exploring the design of voluntary initiatives from the transition management perspective – A means for industrial decarbonization
- 2024
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Ingår i: Energy Reports. - 2352-4847. ; 11, s. 5894-5909
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies claim that national policies fall short of the ambitious goal to limit global temperature increase to well below 2°C, preferably 1.5°C, revealing an ambition gap between current commitments and those needed to reach climate neutrality. To bridge this gap, commitments must increase more than fivefold to achieve the necessary reduction in GHG emissions. Voluntary initiatives (VIs), gaining interest as an approach to support the Paris Agreement's ambition, have the potential to bridge the commitment gap and limit the expected temperature increase to 2°C if all their voluntary commitments to climate neutrality are fulfilled. While decarbonizing the manufacturing sector is crucial for climate targets, no prior study has explored the theoretical potential of industry-related VIs to bridge the gap for industrial decarbonization. This paper addresses this gap by examining the potential contribution of these VIs, analyzing criteria related to arena and agenda creation, operationalization, and accountability. By applying the transition management framework innovatively, the study investigates eighty-three industry-related VIs led by both state and non-state actors. The research process, involving the development of an analytical framework, VIs selection, data collection and validation, categorization, and analysis, provides insights into how the design affects VIs' potential for industrial decarbonization. The main findings highlight, firstly, the need for clearly defined and measurable targets, enhanced commitments, and robust accountability mechanisms, especially for non-state actor-led initiatives. Secondly, increased participation from energy-intensive sector companies due to their pivotal role for GHG emission reduction. Lastly, collaboration between state and non-state actors is critical for bridging the decarbonization gap in manufacturing industries. Additionally, the similarity between VIs and voluntary agreement programs (VAPs) is highlighted, with VAPs been overseen by governmental bodies with administrative authority. Given the urgency of addressing climate change, an unanswered question remains: Will future policies transition away from voluntariness towards more mandatory administrative character?
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| 10. |
- Asim, Muhammad, et al.
(författare)
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Techno-economic assessment of energy and environmental impact of waste-to-energy electricity generation
- 2023
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 9:Suppl 1, s. 1087-1097
-
Tidskriftsartikel (refereegranskat)abstract
- This study explored cumulative 127.5MW waste to energy (WtE) potential in five populous cities of Pakistan based on local waste characterization profiles and global standards. The 50MW WtE plant in Lahore using National electricity regulator codes and practices resulted in an attractive Levelized cost of electricity (LCOE) of US¢ 7.86/kWh over 25 years with a $151.5 million investment cost. The net savings to Lahore Waste Management Company can be $103.4 and $137.7 million respectively with and without tipping fees on account of waste disposal cost, bricks revenue using bottom ash, and waste fee. The project developers can get net savings of $16.9 and $51.5 million respectively with and without tipping fees other than LCOE. Furthermore, the greenhouse gas emissions of 216.6 million tons of CO2eq can be saved throughout plant life against 279 GWh/year energy generation, in terms of grid emission factor and current methane release into the atmosphere from the dumping site.
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| 11. |
- Averfalk, Helge, 1988-, et al.
(författare)
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Domestic hot water design and flow measurements
- 2021
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Ingår i: Energy Reports. - Amsterdam : Elsevier. - 2352-4847. ; 7:Suppl. 4, s. 304-310
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the sizing of primary side components for preparation of domestic hot water are analysed, both qualitatively and based on measurements of domestic hot water demand in one multi-family building with 268 apartments. The collected data spans a period of 18 days during the end of 2020 and is collected in 15-min, 1-min, and 6-s intervals. An overview of the historic development for the design of domestic hot water flow in Sweden is also presented. There is a long-standing argument in Sweden, that the current district heating guidelines result in an overdesign of the flow for domestic hot water. The consequence of this is oversizing heat exchangers and valves in the substations. This study assesses, qualitatively, the issues related to overdesigned primary side valves for preparation of domestic hot water. A revised design for domestic hot water flow for the Swedish context is also conceptualised. The study suggests that an improved design flow for domestic hot water in multi-family buildings can be derived based on empirical measurements. The 15-min intervals are observed to tone down information of peaks to a degree where it is unsuitable to use as basis for a new design flow. The 1-min data does appear to preserve information to a degree where it can be used to assess a design flow when related to data with a 6-s interval. The 6-s data is expected to constitute a resolution that may be less available, and in this study, it constitutes a representation of the real domestic hot water demands. However, to find a fitted curve to empirical data, for the design flow based on number of apartments per multi-family building, the population of datasets needs to be increased. © 2021 The Authors. Published by Elsevier Ltd.
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| 12. |
- Bahaghighat, Mahdi, et al.
(författare)
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Using machine learning and computer vision to estimate the angular velocity of wind turbines in smart grids remotely
- 2021
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 7, s. 8561-8576
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Tidskriftsartikel (refereegranskat)abstract
- Today, power generation from clean and renewable resources such as wind and solar is of great salience. Smart grid technology efficiently responds to the increasing demand for electric power. Intelligent monitoring, control, and maintenance of wind energy facilities are indispensable to increase the performance and efficiency of smart grids (SGs). Integration of state-of-the-art machine learning algorithms and vision sensor networks approaches pave the way toward enhancing the wind farms performance. The generating power in a wind turbine farm is the most critical parameter that should be measured accurately. Produced power is highly related to weather patterns, and a new farm in a near area is also likely to have similar energy generation. Therefore, accurate and perpetual prediction models of the existing wind farms can be led to develop new stations with lower costs. The paper aims to estimate the angular velocity of turbine blades using vision sensors and signal processing. The high wind in the wind farm can cause the camera to vibrate in successive frames, and the noise in the input images can also strengthen the problem. Thanks to couples of solid computer vision algorithms, including FAST (Features from Accelerated Segment Test), SIFT (Scale-Invariant Feature Transform), SURF (Speeded Up Robust Features), BF (Brute-Force), FLANN (Fast Library for Approximate Nearest Neighbors), AE (Autoencoder), and SVM (support vector machines), this paper accurately localizes the Hub and track the presence of the Blade in consecutive frames of a video stream. The simulation results show that determining the hub location and the blade presence in sequential frames results in an accurate estimation of wind turbine angular velocity with 95.36% accuracy. (C) 2021 The Authors. Published by Elsevier Ltd.
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| 13. |
- Bhattacharjee, Shimantika, et al.
(författare)
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Energy and indoor thermal performance analysis of a glazed façade high-rise building under various Nordic climatic conditions
- 2023
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 10, s. 3039-3053
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Tidskriftsartikel (refereegranskat)abstract
- Research has shown that glazed buildings can have higher energy use and are more prone to overheating than other types of buildings. However, few studies have explored the performance of glazed buildings in cold climates. This article aims to evaluate the energy and indoor thermal performance of a high-rise residential building with glazed façades and balconies under Nordic climatic conditions, through a parametric study. Dynamic, whole-year simulations are used to evaluate the impact of four design parameters (with and without glazed balconies, type of balcony glazing, window to wall ratio, and building location within the Nordic region) on the energy and indoor thermal performance of the building. The results show that the building without glazed balconies outperformed that with glazed balconies. Changing from single- to double-pane glazing also helped to reduce energy use and overheating, as did lowering the window-to-wall ratio. Overheating of apartments was found to occur during the summer in five of the six locations simulated, which suggests that solar control strategies might be needed for glazed buildings even in a Nordic climate. This study highlights the importance of further research on glazed residential buildings, which are becoming more common in contexts subject to such climates.
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| 14. |
- Blomqvist, Stefan, 1988-, et al.
(författare)
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Ten years of energy efficiency—Exploring the progress of barriers and drivers in the swedish residential and services sector
- 2022
-
Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 8, s. 14726-14740
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Tidskriftsartikel (refereegranskat)abstract
- Making buildings more energy efficient is an important part of achieving the European Union's energy and climate goals, which several directives, policies, and measures has addressed over the years. This paper aims to study changes over a 10-year period in perception on barriers to and drivers for energy efficiency in the Swedish building sector and identifying success factors. The data collection consists of surveys conducted in 2010 and 2020 among organizations that mainly build, own, and manage multi-dwelling buildings. Besides the overall result, special focus is given to changes depending on type of ownership, size of organization, and organizational hierarchy. Lack of time or other priorities and slim organizations remain the most important barriers, which is most evident among small organizations. Reducing cost remains the major driver. The uncertainty surrounding a rising energy price has diminished and cost-effective solutions are more adaptable. More capital for energy efficiency is available, particularly in the private sector. Furthermore, the result acknowledges the impact of regulatory measures. The study recognizes a connection between organizational development and the integration of energy efficiency in an organizations’ agenda. Future challenges are related to hidden costs and knowledge acquisition.
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| 15. |
- Cabral, Diogo, PhD, 1990-, et al.
(författare)
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Parametric comparison of a CPVT performance evaluation under standard testing procedures - ISO 9806:2017 and IEC 62108:2016 - for an automated and manual 2-axis tracking solar system stand
- 2024
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 11, s. 1242-1255
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Tidskriftsartikel (refereegranskat)abstract
- Currently, a noticeable lack of literature with respect to a wide-ranging comparison of the precision exhibited by automated and manual two-axis tracking solar systems, particularly within the context of adhering to the standard testing protocols delineated by ISO and IEC. To address this research gap, a symmetrical concentrating Photovoltaic-Thermal solar collector underwent a detailed evaluation encompassing two standard testing procedures such as ISO 9806:2017 and IEC 62108:2016. This comprehensive assessment covered thermal and electrical performance parameters, unfolding across two distinct geographical locations: Athens (Greece) and Gävle (Sweden). Within this experimental framework, an automated two-axis tracking solar system stand was employed at the Greek testing site, while in Sweden it was characterized by the employment of a manual two-axis tracking solar system. The collective peak power performance presented marginal divergence within a narrow range of ± 1% across both testing sites. This culminated in an overall peak power output of 1550 Wpeak, which included an electrical peak capacity of 218 Wpeak and a thermal peak power of approximately 1332 Wpeak. Notably, the most pronounced deviation has been materialized in the transversal and longitudinal Incidence Angle Modifier coefficients, with disparities remaining limited to a threshold of < 5%. These findings underscore the commendable precision hallmarking. In summary, the outcomes presented in this study not only contribute to the extant body of knowledge by bridging the existing gap in literature, but also emphasize the precision inherent to manual two-axis tracking solar systems when compared with automated equivalents.
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| 16. |
- Çelik, Onur, et al.
(författare)
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Consumer purchasing behavior and its organizational evaluation toward solar water heating system
- 2023
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 10, s. 1589-1601
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Tidskriftsartikel (refereegranskat)abstract
- Renewable energy sources are fundamental to a country’s economic growth. Solar energy is one of these resources that has a favorable effect on economic growth. Turkey’s solar energy industry is still in its early stages. Due to its location and degree of sunshine each year, the country has a great solar potential. Despite the huge potential, solar energy awareness and utilization are not widespread in all parts of Turkey. In order to identify the factors that affect consumers’ decisions to utilize water heating systems, which is a sort of solar energy system, the purpose of this research is to examine these systems. In this study, all factors influencing consumers’ decisions to acquire solar water heating systems were evaluated holistically for the first time. A questionnaire was used in the study, which is a quantitative research technique. The study identifies the variables that influence consumers’ attitudes toward solar collector purchases and assesses the consequences from an organizational point of view. The study’s results act as a guide for decision-makers.
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| 17. |
- Cruz, Igor, 1986-, et al.
(författare)
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Assessment of the potential for small-scale CHP production using Organic Rankine Cycle (ORC) systems in different geographical contexts: GHG emissions impact and economic feasibility
- 2022
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Ingår i: Energy Reports. - Amsterdam, Netherlands : Elsevier. - 2352-4847. ; 8, s. 7680-7690
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Tidskriftsartikel (refereegranskat)abstract
- According to the European Commission’s 2050 Climate Strategy, renewable electricity is the most important driver for decarbonising the energy system. The intermittent nature of wind and solar creates a demand for dispatchable electricity production that can contribute to a stable and steady supply all year. This supply can be provided, for example, by biomass boilers with combined heat and power production. This paper analyses the potential for small-scale electricity production in Organic Rankine Cycle systems (ORC) in different geographical contexts. The focus is on installing ORC systems with existing biomass-fired boilers in district heating (DH) systems or industry, and with industrial excess heat streams. Economic and climate effects are studied in three countries with different climates and energy-market conditions, namely Sweden, the United Kingdom and Brazil. The results show that there is the potential to install ORC systems around the world that are both economically viable and reduce global greenhouse gas emissions. Equipment size has a large effect on the profitability of the investments. Moreover, the benefits of tax exemptions and certificates for renewable electricity production significantly impact profitability, particularly for smaller equipment sizes.
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| 18. |
- Djaafari, Abdallah, et al.
(författare)
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Hourly predictions of direct normal irradiation using an innovative hybrid LSTM model for concentrating solar power projects in hyper-arid regions
- 2022
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 8, s. 15548-15562
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Tidskriftsartikel (refereegranskat)abstract
- Although solar energy harnessing capacity varies considerably based on the employed solar energy technology and the meteorological conditions, accurate direct normal irradiation (DNI) prediction remains crucial for better planning and management of concentrating solar power systems. This work develops hybrid Long Short-Term Memory (LSTM) models for assessing hourly DNI using meteorological datasets that include relative humidity, air temperature, and global solar irradiation. The study proposes a unique hybrid model, combining a balance-dynamic sine–cosine (BDSCA) algorithm with an LSTM predictor. Combining optimizers and predictors, such hybrid models are rarely developed to estimate DNI, especially in smaller prediction intervals. Therefore, various commonly adopted algorithms in relevant studies have been considered references for evaluating the new hybrid algorithm. The results show that the relative errors of the proposed models do not exceed 2.07%, with a minimum correlation coefficient of 0.99. In addition, the dimensionality of inputs was reduced from four variables to the two most cost-effective variables in DNI prediction. Therefore, these suggested models are reliable for estimating DNI in the arid desert areas of Algeria and other locations with similar climatic features.
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| 19. |
- Duvnjak Zarkovic, Sanja, 1989-, et al.
(författare)
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Integrated reliability centered distribution system planning — Cable routing and switch placement
- 2021
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 7, s. 3099-3115
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Tidskriftsartikel (refereegranskat)abstract
- Distribution utilities aim to operate and plan their network in a secure and economical way. The prime focus of this work is to assist utilities by developing a new integrated approach which considers the impacts of system reliability in distribution system planning (DSP). This approach merges different problems together and solves them in a two-stage process, as follows: 1. cable routing and optimal location and number of switching devices (circuit breakers and reclosers); 2. optimal location and number of tie switches. Moreover, the possibility of installing different cable options, with different prices and capacities, is included. The optimization algorithm is designed using mixed-integer programming (MIP). The developed algorithm analytically evaluates relationships between different components in the system and dynamically updates reliability indices, failure rate and restoration time, of every node in the system. This approach has been tested on two distribution systems. Despite the complexity and the exhaustiveness of the problem, MIP converges and provides the optimal solution for every studied scenario. The results show that an integrated approach enables utilities to obtain more comprehensive solutions. Moreover, by understanding the impact of parameter variation enables utilities to categorize their priorities in the decision making process and optimally invest in distribution network with respect to reliability.
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| 20. |
- Ebeed, Mohamed, et al.
(författare)
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A Modified Artificial Hummingbird Algorithm for solving optimal power flow problem in power systems
- 2024
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Ingår i: Energy Reports. - : ELSEVIER. - 2352-4847. ; 11, s. 982-1005
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Tidskriftsartikel (refereegranskat)abstract
- Optimal power flow (OPF) problem solution is a crucial task for the operators and decision makers to assign the best setting of the system components to obtain the most economic, environmental, and technical suitable state. Artificial Hummingbird Algorithm is a recent optimization algorithm that has been applied to solving several optimization problems. In this paper, a Modified Artificial Hummingbird Algorithm (MAHA) is proposed for improving the performance of the orignal Artificial Hummingbird Algorithm as well as effectivelly solve the OPF problem. The proposed MAHA is based on improving the searching capability by boosting the exploitation using the bandwidth motion around the best solution, while the exploration process is improved using the Levy flight distribution motion and the fitness-distance balance selection. This modified version helps overcome issues such as stagnation, premature convergence, and a propensity for local optima when tackling complex, nonlinear, and non-convex optimization problems like OPF. In order to confirm the effectiveness of the proposed algorithm, a series of tests are conducted on 23 standard benchmark functions, including CEC2020. The resulting outcomes are then compared to those obtained using other algorithms such as fitness-distance balance selection-based stochastic fractal search (FDBSFS), antlion optimizer (ALO), whale optimization algorithm (WOA), sine-cosine algorithm (SCA), fitness-distance balance and learning based artificial bee colony (FDB-TLABC), and traditional artificial hummingbird algorithm (AHA).The proposed algorithm is evaluated by solving the OPF problem with multiple objective functions on the IEEE 30-bus system. These objectives include fuel cost, fuel cost with valve loading effects, power losses, emissions, and voltage profile. Additionally, the algorithm's effectiveness is further assessed by testing it on single objective functions using medium and large-scale IEEE 57 and 118-bus networks.The results obtained by the proposed MAHA demonstrate its power and superiority for solving the OPF problem as well as the standard benchmark functions , surpassing the performance of other reported techniques.
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| 21. |
- Edsand, Hans -Erik, 1979, et al.
(författare)
-
Power struggles: Advances and roadblocks of solar powered mini grids in Tanzania
- 2024
-
Ingår i: ENERGY REPORTS. - 2352-4847. ; 11, s. 342-354
-
Tidskriftsartikel (refereegranskat)abstract
- Rural energy poverty persists in Tanzania, with 77% of the population not having access to electricity. A com-bination of high solar radiation and slow extension of the national energy grid has raised off-grid solar PV based mini-grids as a potential solution. In this paper, a novel extension to the Technological Innovation System (TIS) function approach is used to analyze the positive and negative trends of solar PV based mini-grid diffusion in the country. This framework, adapted for a Global South context, considers key dynamic processes (functions) and structural components (actors and institutions) that are considered essential for diffusion of technological sys-tems, along with the general institutional infrastructure, informal institutions and other contextual factors that may influence the development and implementation of solar PV based mini-grid systems. Based on a combination of semi-structured interviews with key stakeholders and secondary data, the paper identified negative trends in several functions such as market formation, entrepreneurial activities and guidance of the search. The paper demonstrates a clear link between the worsening conditions for solar PV mini-grids with institutional changes as a result of the new political direction for the energy sector that followed the 2015 presidential election in Tanzania.
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| 22. |
- Fang, Yin, et al.
(författare)
-
An accelerated gradient-based optimization development for multi-reservoir hydropower systems optimization
- 2021
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 7, s. 7854-7877
-
Tidskriftsartikel (refereegranskat)abstract
- Hydropower is one of the significant renewable energy resources. It is regularly requested at peak time steps to meet the load requirements of power systems resources allocation. Therefore, modeling the optimal operation of hydropower systems to maximize the entire energy production of reservoir systems can be a vital task for energy investment. Deriving optimal unknown decision parameters of these reservoir systems is a nonlinear, nonconvex, and complex optimization problem. Herein, a novel optimization algorithm, called an accelerated version of gradient-based optimization (AGBO), is developed to solve a complex multi-reservoir hydropower system. This advised technique uses an efficient adaptive control parameters mechanism to stabilize the global and local search; utilizing an enhanced local escaping operator (ELEO) to extend the chances of getting away from local optima; expanding the exploitation search by applying the sequential quadratic programming (SQP) technique. At first, the developed AGBO algorithm is employed to solve the optimal operation of a complex 10-reservoir hydropower system. Secondly, the possibility of the AGBO algorithm within the global optimization problems is illustrated by numerical tests of 23 mathematical benchmark functions. Optimal results show that the proposed AGBO can approach to 0.9999% of the optimal global solution. As a result, the advised method is the most superior one compared to the other advanced optimization algorithms for maximizing the load demands in hydropower system. In conclusion, this offers a productive tool to solve the complex hydropower multi-reservoir optimization systems.
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| 23. |
- Gebresenbet, Girma
(författare)
-
Performance prediction of a pump as a turbine using energy loss analysis
- 2024
-
Ingår i: Energy Reports. - 2352-4847. ; 12, s. 210-225
-
Tidskriftsartikel (refereegranskat)abstract
- As interest in renewable energy sources grows, interest in small-scale hydropower development and utilization increases. The development of micro- and small-scale hydropower plants is challenging, mainly due to the high cost of hydraulic turbines. If the turbine mode performance can be predicted accurately before installation, pumps as turbines (PATs) are an excellent alternative for small-scale hydropower generation. In this study, a theoretical procedure using a detailed energy loss analysis to determine PAT's energy losses is developed, and a non-dimensional performance prediction model is presented. The models were implemented to determine the pressure, head, torque, power, and efficiency across a wide range of flow rates. This work clearly characterizes the effects of individual losses, thereby acknowledging their influence. The prediction results were tested at ten different flow rates, ranging from 50 % to 180 %. The model result was validated through experiments using a hydro-pump test rig developed at the Bahir Dar Institute of Technology at Bahir Dar University. The numerical and model results have good agreement with the experimental results. at BEP The experimental result gives a 1.6 flow rate, 1.72 head ratios, and an efficiency of 76.53 %, 78.09 %, and 74.04 % using analytical, numerical, and experimental methods, respectively. The PAT off-design efficiency decreases sharply below BEP and smoothly above BEP. At BEP, the CFD and analytical results deviated by -2.04 % and 3.08 %, respectively, from the experimental results. Further, the detailed energy loss analysis revealed that the volute frictional (12.1 %), the throat frictional (11.9 %), the inlet pipe frictional (11.2 %), the impeller frictional (9.4 %), and the volute diffusion (8.9 %) losses take the major energy losses sequentially. This provides full insight for applying performance optimization measures.
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| 24. |
- Gubin, Pavel Y., et al.
(författare)
-
Optimizing generating unit maintenance with the league championship method: A reliability-based approach
- 2023
-
Ingår i: Energy Reports. - : ELSEVIER. - 2352-4847. ; 10, s. 135-152
-
Tidskriftsartikel (refereegranskat)abstract
- The electrical power industry has experienced an unprecedented pace of digital transformation as a prevailing economic trend in recent years. This shift towards digitalization has resulted in an increasing interest in the collection of real-time equipment condition data, which provides opportunities for implementing sensor-driven condition-based repair. As a result, there is a growing need for the development of generator maintenance scheduling to consider probabilistic equipment behavior, which requires significant computational efforts. To address this issue, the research proposes the use of a meta-heuristic league championship method (LCM) for generator maintenance scheduling, considering random generation profiles based on generation adequacy criteria. The experimental part of the study compares this approach and its modifications to widely used meta-heuristics, such as differential evolution and particle swarm methods. The identification and demonstration of optimal method settings for the generation maintenance scheduling problem are presented. Subsequently, it is illustrated that employing random league scheduling expedience can reduce the variance of objective function values in resulting plans by over three times, with values of 0.632 MWh and 0.205 MWh for conventional and proposed techniques respectively. In addition, three approaches are compared to assess generation adequacy corresponding to different schedules. The study emphasizes the efficacy of employing the LCM approach in scheduling generator maintenance. Specifically, it showcases that among all the methods examined, the LCM approach exhibits the lowest variance in objective function values, with values of 38.81 and 39.90 MWh for LCM and its closest rival, the modified particle swarm method (MPSM), respectively.& COPY; 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 25. |
- Gunasekara, Saman Nimali, Dr. 1982-, et al.
(författare)
-
Distributed cold storage in district cooling-Grid dynamics and optimal integration for a Swedish case study
- 2021
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 7, s. 419-429
-
Tidskriftsartikel (refereegranskat)abstract
- District cooling (DC) is gaining interest with global warming and rising demands on indoor comfort. As DC grid expansions are capital intensive, cost effective alternatives to meet these rising cooling demands are desired. Integrating cold storage (CS) into the grids is one attractive choice, allowing peak shaving, load shifting, and renewable electricity recovery via power-to cold. To analyze the impact of new CSs, the DC distribution grid dynamics must be investigated. This work evaluates the implementation of several new CSs into an existing DC system (called the base case-BC), to find the optimal solution. This is performed considering the case study DC system of Norrenergi AB, Sweden, catering to Solna and Sundbyberg via three production plants Solnaverket, Sundbybergsverket and Frosundaverket, and a 10 MW CS (in Solnaverket). The software tool Netsim is used for distribution grid dynamics analysis of the BC and three scenarios with additional cold storages, for the optimization of differential pressure (dP) of the grids to be within 100-800 kPa. These scenarios include: one additional 15 MW CS in Sundbybergsverket (Scenario 1), one additional 15 MW CS in Frosunda (Scenario 2) and two additional 3 MW CSs in Sundbybergsverket and Frosunda (Scenario 3). The CSs in Sundbybergsverket are centrally placed, whereas, those in Frosunda were positioned in a grid loop experiencing low differential pressure, identified in Netsim simulations of BC. The simulations were done for 24 h at 1-hour resolution, on a chosen historically highest demand day (02 August 2018). The results indicate that the optimal solution is implementing two additional CSs in Sundbybergsverket (centralized) and Frosunda (distributed), each with a capacity between 3-7.5 MW (6-15 MW total capacities). Further evaluations to determine the optimal sizing of these CSs is the next step in this study.
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| 26. |
- Habib, Md Zakaria, et al.
(författare)
-
Distributed fault-passage indicators versus central fault location : Comparison for reliability centred planning of resonant-earthed distribution systems
- 2023
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 9, s. 1731-1742
-
Tidskriftsartikel (refereegranskat)abstract
- Fault location methods are crucial for reducing fault restoration time, and thus improving a network's system average interruption duration index (SAIDI) and customer outage cost. Resonant-earthed systems pose problems for traditional fault location methods, leading to poor accuracy and a need for additional complexity. In this context, methods that detect fault direction (fault-passage indicators, FPI) at multiple points in the network may show advantages over a central distance-estimation method using fault locators (FL) of poor accuracy. This paper includes a comparative study of these two major fault location methods, comparing the reliability benefit from a varied number of FPIs or a central method. The optimal placement of the fault locating devices is found by formulating a mixed-integer linear programming (MILP) optimization approach that minimizes both outage and investment costs and assesses SAIDI. This approach has been tested on an example distribution system. However, to justify the universality of the algorithm, the RBTS reliability test system has also been analysed. The comparison of location methods and placement method of FPIs are useful for reliability centred planning of resonant-earthed distribution systems where fault location is to be used. Results show that a small number of FPIs that give accurate identification of direction may give more cost effective increase in reliability than a distance estimate by FL with typical levels of inaccuracy.
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| 27. |
- Huang, Pei, et al.
(författare)
-
Investigation of the Peer-to-Peer energy trading performances in a local community under the future climate change scenario in Sweden
- 2022
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 8, s. 989-1001
-
Tidskriftsartikel (refereegranskat)abstract
- Peer-to-peer (P2P) energy sharing among neighboring households is a promising solution to mitigating the difficulties of renewable power (such as solar Photovoltaics (PV)) penetration on the power grid. Until now, there is still a lack of study on the impacts of future climate change on the P2P energy trading performances. The future climate change will cause variances in the renewable energy production and further lead to changes in the economic performances of households with various energy uses and affect the decision making in PV ownership and pricing strategies. Being unaware of these impacts could potentially hinder the P2P energy sharing application in practice. To bridge such knowledge gap, this paper conducts a systematic investigation of the climate change impacts on the energy sharing performance in solar PV power shared communities. The future weather data is generated using the Morphine method, and an agent-based modeling method is used for simulating the energy trading behaviors of households. Four comparative scenarios of different PV ownerships and pricing strategies are designed. The detailed energy trading performances (including the PV power self-sufficiency, cost saving, revenues, and compound annual growth rate) for the four comparative scenarios are analyzed under both the present and future climates and compared. The study results of a building community located in Sweden show that the future climate change is more beneficial to large energy use households while less beneficial to small households. High price of energy trading can improve the fairness of the economic performances in the community, especially when some of the households do not have any PV ownership. This study can help understand the future climate impacts on the energy sharing performances of building communities, which can in turn guide decision making in PV ownership and price setting for different households under the future climate change to facilitate real applications. © 2021 The Author(s)
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| 28. |
- Iqbal, Wasif, et al.
(författare)
-
Techno-economic and emission analysis of solar assisted desiccant dehumidification: An experimental and numerical study
- 2023
-
Ingår i: Energy Reports. - : ELSEVIER. - 2352-4847. ; 10, s. 2640-2654
-
Tidskriftsartikel (refereegranskat)abstract
- In humid climates, it is challenging to maintain moisture content in the air for human thermal comfort and industrial applications. Commercial dehumidifiers rely on conventional electric heaters to regenerate desiccant material, which accounts for significant energy consumption by such dehumidifiers. As a green solution to this problem, the present study integrates a flat plate solar air collector (FPSAC) with a desiccant dehumidifier to effectively use solar thermal energy and reduce electrical consumption. Performance evaluation of glazed and unglazed FPSAC-assisted desiccant dehumidifier has been conducted at process air flow rates of 33, 51 and 62 m3/h with a constant regeneration flow rate of 42 m3/h. Both glazed and unglazed FPSAC assisted desiccant dehumidification systems had the highest dehumidification effectiveness and percentage increase in temperature at the flow rate of 33 m3/h, while the highest moisture removal capacity was at 51 m3/h. Maximum dehumidification effectiveness, percentage temperature increase, and moisture removal capacity for the glazed case were 0.4, 66.67%, and 6.14 kg/h, respectively. Experimental results showed that the glazed FPSAC-integrated desiccant dehumidification system outperforms unglazed FPSAC in all performance evaluation parameters. Using Transient System Simulation software (TRNSYS), the proposed glazed and unglazed assisted desiccant dehumidification system was modeled and validated with experimental results. Furthermore, a techno-economic analysis of the solar hybrid desiccant dehumidification system has been carried out. The FPSAC used in this study showcased a 33.57% yearly solar fraction with a solar hybrid system having a payback period of 4.23 years. In addition, the hybrid system can reduce greenhouse gas emissions yearly by 0.352 tons of CO2 equivalents.
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| 29. |
- Jaouaf, Salaheddine, et al.
(författare)
-
Passive strategies for energy-efficient educational facilities : Insights from a mediterranean primary school
- 2024
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 11, s. 3653-3683
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the thermal and energetic dynamics of primary school classrooms in a Mediterranean climate in Khoualed Abdel Hakeem, Ain Temouchent County, Algeria. The research highlights significant optimizations by focusing on passive strategies such as external shading devices, Window-to-Wall Ratio (WWR), glazing types, and building envelope adjustments. Our simulations, validated rigorously, showcase a remarkable congruence with actual electricity consumption, affirming the reliability and efficacy of our simulation model as a valuable predictive tool. A Vertical Shading Angle (VSA) of 60° proves optimal, resulting in an impressive 11% reduction in Annual Energy Consumption (AEC). A recommended WWR of 30% demonstrates an 11% decrease in AEC and improves thermal and energy efficiency. Double Low Emissivity (Double-Low E) glazing is found to be superior, resulting in a significant 14% decrease in AEC. Achieving a WWR of 50% in shaded areas helps maintain a well-balanced thermal environment, resulting in a 12% reduction in heating and cooling requirements. The integration of passive strategies in the optimized model showcases a remarkable 44% overall reduction in energy consumption. The results highlight the efficacy of passive strategies, promoting energy-conscious and ecologically responsible practices, advocating for their incorporation in educational facilities, and offering valuable insights for sustainable school building design.
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| 30. |
- Ji, Linan, et al.
(författare)
-
An overview of the progress of new working pairs in absorption heat pumps
- 2023
-
Ingår i: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 9, s. 703-729
-
Forskningsöversikt (refereegranskat)abstract
- Absorption heat pumps have emerged as a potential tool to address the energy crisis because of their ability to utilize low-grade heat. The performance of an absorption heat pump largely depends on the efficiency of the working pair to operate at the source temperature. The commercialized working pairs H2O/LiBr and NH3/H2O linger with operational and economic issues. Several binary/ternary combinations were tested among water, ammonia, salt, alcohols, hydrocarbons, and ionic liquids (ILs) in quest of the potential working pairs. The last decade has witnessed a stupendous surge in IL-based working pairs because of their several advantageous properties over the traditional solvents. The present review encompasses the research progress on various working pairs, in particular, their properties, modeling and correlation results, and coefficient of performance (COP) values.
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| 31. |
- Kheloufi, S., et al.
(författare)
-
Multi-energy planning of a city neighbourhood and improved stakeholders' engagement-Application to a Swiss test-case
- 2021
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 7, s. 343-350
-
Tidskriftsartikel (refereegranskat)abstract
- During the IntegrCiTy project, a novel urban energy planning approach was successfully tested. The latter combines stakeholder engagement with an innovative multi-energy model using different control strategies, while combining both energy demand and supply dynamics on selected zones. The applied control strategies applied to the energy networks show the potential gains linked to using synergies among networks and technologies, as to foster renewable energy penetration in the system. Thanks to the combined approach of advanced optimization techniques and stakeholder engagement, solutions can be identified much quicker. In addition, unfeasible solutions can be discarded at earlier stages of the planning process, based on the feedback of the stakeholders even though, from a pure mathematical and energy point of view, the solutions might be theoretically interesting to consider.
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| 32. |
- Kranenbarg, Jelle, et al.
(författare)
-
Uncertainty in the numerical prediction of the tangential velocity in axial turbines at part load operations: A parametric study
- 2023
-
Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 10, s. 2597-2611
-
Tidskriftsartikel (refereegranskat)abstract
- Numerical simulations of axial hydraulic turbines away from the best efficiency point are challenging. Previous studies especially show difficulties predicting the tangential velocity at Part Load (PL) operating conditions, where the swirl is high, in comparison to experiments. This is a reoccurring problem, and it is essential to understand, as the high tangential velocity is a fundamental characteristic of the flow in hydraulic turbines and is directly related to the swirling flow stability and the turbine's power output. The objective of this study is to numerically investigate and understand the origin of the tangential velocity deviation from experimental results by performing simulations with the finite volume method of an axial turbine operated at PL. A parametric study is performed to address the abovementioned. Specifically, the effects of the blade clearance, blade angle, flow rate, and different turbulence models are studied on this issue. Results are analyzed by comparing the predicted axial and tangential velocity profiles and torque to experimentally obtained values. Primarily the runner inter-blades flow is studied as there is a knowledge gap. In addition, the physical phenomena responsible for head losses are studied in detail. Results show that the model can predict the flow relatively well at optimal flow conditions with low swirl but has problems at part load; the tangential velocity between the runner blades is underestimated by ∼20%. The undervalued head losses are the root cause. They result in an overestimated torque and an underestimated tangential velocity as the runner extracts too much energy from the fluid. A small modeling error of 0.5° in the blade angle and a change of 3% in the flow rate significantly affect the tangential velocity and torque prediction. The studied parameters must be considered carefully when building a numerical model.
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| 33. |
- Levihn, Fabian, 1983-, et al.
(författare)
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Introducing BECCS through HPC to the research agenda : The case of combined heat and power in Stockholm
- 2019
-
Ingår i: Energy Reports. - : ELSEVIER. - 2352-4847. ; 5, s. 1381-1389
-
Tidskriftsartikel (refereegranskat)abstract
- In the years since COP21 in Paris, awareness of the need for carbon sinks has grown rapidly. However, policy instruments supporting a path to this target are still lacking. Bioenergy carbon capture and storage (BECCS) may provide a way to rapidly reduce global warming. In the Nordics, much of the basic infrastructure for successful BECCS implementation is already in place. So why is not more happening? This study provides insights to barriers and policy implications in relation to successful BECCS implementation. Though implementation could support economic growth and welfare development, the cost is relatively high for individual utilities. In the deregulated competitive heating market in the case of Stockholm, cost transfer to customers is prohibited, effectively impeding implementation. Moreover, while present national or EU-based support schemes could cover investments, the operating cost is high, so other economic policy approaches are required. Lastly, this paper shows that BECCS on combined heat and power plants has a potential, but requires much more research. Thus it is suggested that negative emission technologies in energy systems are brought into research agendas such as the future of combined heat and power and urban multi energy systems.
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| 34. |
- Li, Fangfei, et al.
(författare)
-
Application and analysis of flip mechanism in the melting process of a triplex-tube latent heat energy storage unit
- 2023
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 9, s. 3989-4004
-
Tidskriftsartikel (refereegranskat)abstract
- In order to improve the characteristics of uneven melting in the melting process of the horizontal latent heat energy storage system, the triplex-tube latent heat energy storage unit is taken as the research object, and the flip mechanism is applied to its melting process. Numerical simulation is used for the research, and the numerical model is verified by experimental data. The results show that under different dimensionless times, the melting performance of the unit can be significantly improved by a single flip. When the dimensionless time is 0.4576, it is found that the total melting time of the unit is reduced by 16.17 %, the average heat absorption rate is increased by 14.7 %, but the total heat energy absorption is reduced by 3.85 %. The results show that the addition of a flip can effectively shorten the melting time and increase the heat absorption rate, but it has a negative effect on the total heat absorption in one melting cycle. Moreover, through the comparison of dynamic flow rate, dynamic temperature response, and temperature interval, it is shown that the addition of flip effectively reduces the negative influence of the hard-to-melt zone on the melting performance of the unit during the melting process. The flip mechanism reduces the proportion of high-temperature phase change material in the melting process and makes the melting process more uniform.
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| 35. |
- Li, Zhongtian, et al.
(författare)
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Impact of turbine availability and wake effect on the application of dynamic thermal rating of wind farm export transformers
- 2024
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 11, s. 1399-1411
-
Tidskriftsartikel (refereegranskat)abstract
- Dynamic thermal rating allows transformers to operate beyond the nameplate rating according to the actual weather and loading conditions. This paper proposes a methodology to improve the application of this technology in the design of new transformers or in the operation of existing transformers connected to wind farms by accurately predicting their load profiles, accounting for the influence of wake effect and turbine availability. Specifically, the variation of turbine availability due to the intermittent wind is considered in the load profile estimation. Additionally, a correction method, which can be incorporated into any wake model, is proposed to improve the accuracy of wake loss computation. A case study shows that the wake effect and the changing turbine availability shorten the time that the transformers maintain at full load, thereby reducing the aging rate of the wind farm export transformers. The findings suggest that considering these two factors in the DTR application can benefit the longevity and efficiency of wind farm exported transformers.
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| 36. |
- Linjee, Siwat, et al.
(författare)
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Corrosion behaviour improvement from the ultrafine-grained Al–Zn–In alloys in Al–air battery
- 2022
-
Ingår i: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 8, s. 5117-5128
-
Tidskriftsartikel (refereegranskat)abstract
- Corrosion of aluminium anode in alkaline solution is a challenging matter for the development of a long-life aluminium anode in Al–air battery. This research focuses on grain size reduction by equal channel angular pressing (ECAP) of Al, Al–Zn, and Al–Zn–In samples. The average grain size of all samples after ECAP is lower than 1μm. Open circuit potential, potentiodynamic polarisation, electrochemical impedance spectroscopy, and self-corrosion test were carried out to study the effects of alloying elements (Zn, In) and grain size reduction by ECAP on the electrochemical behaviours of aluminium alloy anodes. The results show that alloying element, zinc, can improve the stability of ion dissolution by porous Al2ZnO4 film formation. Indium can activate ion dissolution that causes enhanced electrochemical activities for Al–Zn–In sample. Moreover, increasing grain boundaries through grain size reduction can enhance more negative potential and cause a uniformly corroded surface of Al–Zn–In sample, leading to a longer anode life in alkaline solution. © 2022 The Authors
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| 37. |
- Liu, Suhong, et al.
(författare)
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Energy analysis using carbon and metallic oxides-based nanomaterials inside a solar collector
- 2020
-
Ingår i: Energy Reports. - Germany : Elsevier. - 2352-4847. ; 6, s. 1373-1381
-
Tidskriftsartikel (refereegranskat)abstract
- The effectiveness of a flat-plate solar collector was studied by using SiO2, Al2O3, Graphene, and graphene nanoplatelets nanofluids with distilled water as the working fluids. The energy efficiency was theoretically compared using MATLAB programming. The prepared carbon and metallic oxides nanomaterials were structurally and morphologically characterized via field emission scanning electron microscope. The study was conducted under different operating conditions such as different volume fractions (0.25%, 0.5%, 0.75% and 1%), fluid mass flow rate (0.0085, 0.017, and 0.0255 kg/s), input temperatures (30, 40, and 50 °C), and solar irradiance (500, 750, and 1000 W/m2). Nanofluids showed better thermophysical properties compared to standard working fluids. With the addition of the nanofluids SiO2, Al2O3, Gr and GNPs to the FPSC the highest efficiency of 64.45%, 67.03%, 72.45%, and 76.56% respectively was reached. The results suggested that nanofluids made from carbon nanostructures and metallic oxides can be used in solar collectors to increase the parameters of heat absorbed/loss compared to water only usage.
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| 38. |
- Liu, Z., et al.
(författare)
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Effect of soil moisture content on thermal performance of ground source heat exchangers : An electromagnetism topology-based analysis
- 2023
-
Ingår i: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 10, s. 3914-3928
-
Tidskriftsartikel (refereegranskat)abstract
- Ground source heat pump (GSHP) technology has gained significant attention as a viable solution for the heating, ventilation, and air conditioning (HVAC) of buildings. One of the factors that can impact the performance of GSHP systems is the soil moisture content. In this study, an innovative approach, referred to as soil impedance topology, is introduced as an alternative to traditional methods for measuring soil moisture content in geothermal heat pump systems. This method is inspired by pipeline grid utilizes impedance measurement, which provides a direct measurement of soil moisture content without the need for sensors. The study also proposes a changing rule of impedance with varying moisture content, where capacitance increases and resistance decreases when the soil moisture content is less than 20% but stabilizes beyond a water content of 20%. The accuracy of the topological mechanism prediction method is high, as demonstrated through the verification of the Smith circle and measured data. However, it is noted that the performance may be insufficient in the high frequency band and high soil moisture content. The use of impedance topology provides a more accurate and reliable method for measuring soil moisture content as well as for modeling and predicting heat transfer rates and system performance. This technology has strong potential to improve efficiency, reduce energy costs, and enhance the environmental sustainability of geothermal heat pump systems.
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| 39. |
- Liu, Z., et al.
(författare)
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Multi-objective optimizations and multi-criteria assessments for a nanofluid-aided geothermal PV hybrid system
- 2023
-
Ingår i: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 9, s. 96-113
-
Tidskriftsartikel (refereegranskat)abstract
- Energy transition has brought widespread attentions to the concept of coupled utilization of the geothermal and solar energy. This paper provides an integrated assessment on developing a nanofluid geothermal-photovoltaic hybrid system that addresses the multi-objective optimization and multi-criteria evaluation difficulties. The coupling system design and dispatch are optimized by considering the multiple objectives from the microscopic particles to the system. The life cycle cost, levelized cost of energy, levelized cost of heat, and the irreversibility are introduced in the optimization stage. The optimization parameters include the pipe arrangement, type of nanoparticles, and the concentration of the nanoparticles in nanofluids. A combined analysis including the energy, exergy, economy, and the environment is proposed to evaluate the various objectives and cases. The results show that the combination of 2% Al2O3 nanofluid and spiral pipe has the optimum performance. The monocrystalline solar panels with the nanofluids-aided heat pump create the least CO2 emissions (550 kg/year), the least LCOE (198.18 $), and the highest exergy efficiency. However, the LCOH (211.78 $/MWh) is still much high. Only when the electricity cost is higher than 0.11$/kWh, the proposed coupling system would show competitiveness. In summary, these results effectively prove the robustness and superiority of the hybrid system.
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| 40. |
- Mahmud, Shadman, et al.
(författare)
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Bioethanol and biodiesel blended fuels : Feasibility analysis of biofuel feedstocks in Bangladesh
- 2022
-
Ingår i: Energy Reports. - Oxford, United Kingdom : John Wiley & Sons. - 2352-4847. ; 8, s. 1741-1756
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Forskningsöversikt (refereegranskat)abstract
- In 2019–2020, Bangladesh imported 5.2 million metric tonnes of petroleum products, worth 2.5 billion USD, and 50% of the imports were consumed by the transportation sector. Having limited natural oil reserves and being heavily dependent on oil imports, the country is vulnerable to shocks in the international oil market, which can jeopardize its consistent economic growth. The Government announced a 5% blending of bioethanol with gasoline in 2017, with broken rice, maize, and molasses as the feedstocks, but sourcing biofuel from food crops can hamper the country’s food security. This study explores second and third generation feedstocks e.g., organic plants, seeds, agricultural residues, and waste animal fat or skin that can be collected and processed for the extraction of biofuels. Technical potential of biofuel from the feedstocks is analysed which shows that Bangladesh has a potential to extract 44.4 million metric tonnes of bioethanol in a year from agricultural residues with rice residue having the highest potential (71%). Ground nut and rubber seeds can be major feedstocks for biodiesel production having a potential of 61,000 and 42,000 metric tonnes per year, respectively. Waste chicken skin can be another promising feedstock for the extraction of biodiesel. Biofuels extracted from these non-edible feedstocks and blended with existing transport fuels can lessen Bangladesh’s import bills through a sustainable, environmentally friendly manner.
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| 41. |
- Marques, Luciana, et al.
(författare)
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Categorizing shared photovoltaic business models in renewable markets : An approach based on CANVAS and transaction costs
- 2023
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 10, s. 1602-1617
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Tidskriftsartikel (refereegranskat)abstract
- Shared Photovoltaic (PV) business models enable a broader percentage of consumers to benefit from renewable energy because installation and transaction costs are significantly decreased. Designing these shared and community-based business models can contribute to help countries achieve emission reduction targets, particularly in developing countries. A systematization in different categories of how these business models can improve the awareness of opportunities and barriers to such models, including the identification of potential models is yet to be explored in a specific market. This paper proposes such categorization and discusses different shared PV business models observed in this sector, discussing the main similarities and differences of each one based on the CANVAS business model methodology. Further, this paper analyzes these categories in terms of how the decrease in transaction costs from the consumers’ perspective would help to deliver value. Finally, we demonstrate the proposed categorization to existing models in Brazilian and Indian markets, defining which business model categories are more adherent to this market. Moreover, we discuss possible innovative models yet to be applied to these developing countries and barriers to be overcome. It was identified that major existing business models are feasible for both India and Brazil, however, regulatory hindrances needs to be addressed beforehand.
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| 42. |
- Matviychuk, Andriy, et al.
(författare)
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Modeling carbon dioxide emissions reduction
- 2024
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 12, s. 1876-1887
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Tidskriftsartikel (refereegranskat)abstract
- The paper proposes a new scientific approach to modeling carbon dioxide (CO2) emissions in individual countries, based on the tools of Kohonen self-organizing maps and the provisions of economic theory. This work is based on conducted a comprehensive analysis of wide set of indicators influencing carbon dioxide emissions and decarbonization processes in 40 selected countries for 10 years time span from 2013 till 2022. During clustering these nations using self-organizing maps, 14 key indicators were chosen that cover economic and demographic growth, energy consumption, CO2 emission data, and includes trade of energy recourses for wider analysis and identification of countries with similar decarbonization potential, economic development and trade energy recourses possibilities. This approach exposed distinct clusters of nations with varying decarbonization capabilities and tracked the progress of analyzed countries in terms of CO2 emission changes in dynamic.The analysis of clustering was focused on identification leaders and followers in decarbonization activities. The leaders cluster includes Sweden, Norway, New Zealand and other countries exhibited leadership in developing a climate-resilient economy among 40 countries. Hence, all countries positioned closer to the leader cluster on the map demonstrated higher efficiency in their decarbonization pathways. Consequently, these properties of Kohonen maps provide a foundation for formulating general recommendations to achieve an efficient and effective low-carbon economy for followers including Ukraine, Kazakhstan and other energy intensive countries.Distinct countries decarbonization profiles resulting from clustering were used to develop practical recommendations towards estimating and establishing targeted CO2 emission levels for analyzed countries, conducting continued promoting renewable energy utilization, enhancing cross-border energy trade, diversifying energy portfolios, etc. Also, the proposed methodology can be utilized to project future emissions trends for each country based on cluster-specific models and facilitate policy decisions making process related to mitigating carbon emissions.
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| 43. |
- Mevada, Dinesh, et al.
(författare)
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Experimental performance evaluation of solar still with zig-zag shape air cooled condenser: An energy-exergy analysis approach
- 2023
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Ingår i: Energy Reports. - : ELSEVIER. - 2352-4847. ; 10, s. 1198-1210
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Tidskriftsartikel (refereegranskat)abstract
- In the present experimental effort is made to increase the performance of a solar still (SS) by including a novel design of a zig-zag-shaped air-cooled condenser (ZZACC) and cuprous oxide (CuO) as a nanomaterial. Research work is conducted in the climatic conditions of Gandhinagar, Gujarat, India, from September to November 2020. A comparison was made to assess the performance of a conventional solar still (CSS) and a solar still equipped with a zig-zag shape air-cooled condenser (SSWZZACC) with CuO. The experiments findings showed that adding CuO to SSWZZACC increases the distillate production by 46.83% and the daily energy efficiency by 45.98%, respectively, compared to CSS. Also, SSWZZACC demonstrates a better efficiency of exergy and latent heat of vaporization than CSS because CuO causes an increase in the evaporative heat transfer coefficient of water. In life cycle cost analysis study discovered that SSWZZACC has a 27.77% lower cost per litre of water (CPL) than CSS. The obtained maximum energy and exergy efficiency values for CSS and SSWZZACC were 2.36% & 25.75% and 3.9% & 37.59%, respectively. In economic and environmental aspects, it was found that SSWZZACC with CuO showed a cost-effective desalination unit and was highly effective from a carbon credit point of view (CCP) by CO2 mitigation.& COPY; 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 44. |
- Monteiro, Helena, et al.
(författare)
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Energy and material efficiency strategies enabled by metal additive manufacturing – A review for the aeronautic and aerospace sectors
- 2022
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 8:3, s. 298-305
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Tidskriftsartikel (refereegranskat)abstract
- Conventional manufacturing of aeronautic and aerospace parts requires substantial amount of resources (energy and materials) while generating high quantities of waste and carbon dioxide emissions. Metal additive manufacturing (MAM) has the potential to reduce resource consumption, which is particularly important for energy-intensive materials such as titanium. We undertake a systematic literature review of MAM processes for the aerospace/aeronautic sector focusing on energy and material efficiency. Relevant literature was classified and discussed based on the life cycle stages at which resource efficiency strategies for MAM were identified: (1) product design; (2) material development and sourcing; (3) processes development, control, and optimization; (4) end-of-life extension and circular economy. Results highlight the key factors required to optimize MAM and the relevance of assessing its environmental impact compared to conventional manufacturing. Material and energy efficiency vary significantly between different MAM processes due to several factors directly linked to the process but also associated with the supply chain, e.g. electricity mix or material sourcing. Further research could explore new trends in technological development for circularity or multi-material MAM.
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| 45. |
- Negahdar, Houshmand, et al.
(författare)
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Reinforcement learning-based event-triggered secondary control of DC microgrids
- 2024
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Ingår i: Energy Reports. - 2352-4847. ; 11, s. 2818-2831
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a reinforcement learning (RL)-based event-triggered mechanism (ETM) for employing in the secondary control layer (SCL) of DC microgrids is developed. The proposed RL-based ETM satisfies the SCL objectives, which is overcoming the disadvantages of primary control (such as voltage deviation and inappropriate current sharing among the distributed generating units). More importantly, it also aids in reducing the amount of transmitted data exchanged within all the distributed generators (DGs). The design parameters of the ETM scheme are regulated through a robust RL approach to provide adaptive ETM parameter tuning, enabling the ETM error vector threshold to quickly adapt to changes in the MG. The suggested RL-based ETM approach is implemented in a DC microgrid, and utilizing hardware in the loop (HIL) real-time OPAL-RT experimental tests, its performance in the SCL of DC microgrids is investigated. Experimental validations have confirmed the merits of the proposed approach.
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| 46. |
- Palm, Jenny, et al.
(författare)
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Understanding tenants’ responses to energy efficiency renovations in public housing in Sweden : From the resigned to the demanding
- 2020
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 6, s. 2619-2626
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the experiences of tenants in renovation projects of public housing rental apartments in Sweden. Tenants’ perspectives are under-researched in the context of energy efficiency renovation projects, which is a considerable oversight given the many ways in which such projects impact their lives. The aim of the paper is to reveal rare qualitative insights into tenants’ experiences of, and attitudes towards, energy efficiency renovations in a public housing context and the extent to which they feel motivated and able to influence the renovation project. Participatory observations at tenant meetings were conducted as well as semi-structured phone interviews. An empirically driven typology is developed indicating that tenants have different interests and attitudes regarding energy efficiency renovations. Six different types are identified: the satisfied; the demanding, the conservative, the resigned, the sceptical and the resistant.
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| 47. |
- Qin, Haihong, et al.
(författare)
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An optimized parameter design method of SiC/Si hybrid switch considering turn-off current spike
- 2022
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 8, s. 789-797
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Tidskriftsartikel (refereegranskat)abstract
- In order to reduce the switching loss of SiC MOSFET/Si IGBT (SiC/Si) hybrid switch, the switching mode that turn off the Si IGBT prior to the SiC MOSFET is generally adopted to achieved the zero-voltage switching operation of IGBT. The minority carrier in N-base region of the IGBT are recombined in the form of exponential attenuation due to the conductivity modulation effect. When the SiC MOSFET is turned off, if the carrier recombination process of the IGBT is not finished, it needs to bear a large collector–emitter voltage change rate, resulting in apparent current spike. This current spike will increase the current stress of the device and produce additional turn-off loss. The equivalent model of double pulse test circuit of SiC/Si hybrid switch considering parasitic parameters is established, and the turn-off transient process is given analytically. The influence of turn-off delay time, circuit parameters and working conditions on current spike are analysed quantitatively. Combined with the consideration of device stress and comprehensive turn-off loss, an optimized circuit design method of SiC/Si hybrid switch considering turn-off current peak is proposed, which provides theoretical and design guidance for high reliability and high efficiency SiC/Si-based converters.
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| 48. |
- Qin, Haihong, et al.
(författare)
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Design of overvoltage suppression filter based on high-frequency modeling of cable in SiC based motor drive
- 2022
-
Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 8, s. 822-831
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Tidskriftsartikel (refereegranskat)abstract
- SiC-based motor drives have the advantages of achieving higher efficiency and higher power density than traditional Si-based motor drives, and are gradually being widely used in electric power transmission. Due to different application situations such as oil field and airplane, a long cable is applied between the motor drive and three-phase motor and the distance may exceed hundreds of meters, which will cause serious voltage reflection problem, damaging working life of the motor. Meanwhile, the high slew rate of output voltage created by SiC-based motor drive deteriorates this phenomenon. In order to solve this problem, we first analyze the principle and influencing factors of voltage reflection, and establish the equivalent circuit model of the long cable. Then we put forward design method of LRC passive filter to suppress voltage reflection, and give simulation analysis. At last we built an experimental platform to verify the effectiveness of the LRC passive filter in SiC-based motor drive, and the experimental results show that the LRC passive filter with optimized parameters has good suppression effect of voltage reflection.
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| 49. |
- Qin, Haihong, et al.
(författare)
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Evaluation of antiparallel SiC Schottky diode in SiC MOSFET phase-leg configuration of synchronous rectifier
- 2023
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Ingår i: Energy Reports. - 2352-4847. ; 9, s. 337-342
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Tidskriftsartikel (refereegranskat)abstract
- The MOSFET synchronous rectification (SR) is widely used to reduce the conduction loss during the freewheeling period. Due to the wide band gap of silicon carbide (SiC), the intrinsic body diode of SiC MOSFET exhibits a high voltage drop. Therefore, SiC Schottky diodes (SBD) and SiC MOSFETs are usually used in reverse parallel to reduce power loss. However, the increase of equivalent junction capacitance due to the addition of an external SiC SBD could bring larger turn-on current on opposite power transistor of the phase-leg. Furthermore, as the parasitic inductance associated with layout hinders the prompt transfer of current between SiC SBD and body diode, the external SiC SBD cannot be fully utilized, and it may deteriorate the overall performance, especially at heavy load. We comprehensively compare power losses when SiC SBD are antiparallel or not, at different working conditions, including different layout compactness, load current and dead time. It's hard to get the effect of loss reduction loss when add antiparallel SiC SBD due to the parasitic inductance induced by the layout. The results can provide a guidance to properly select SiC SBD in a phase-leg configuration under SR mode for freewheeling during the dead time.
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| 50. |
- Qiu, Kaiqing, et al.
(författare)
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Reliability evaluation of power distribution grids considering the dynamic charging mode of electric buses
- 2021
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 7, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Advances in wireless power transfer technology provide the possibility to construct electrified roads and charge electric vehicles driving on the road. Dynamic charging mode enables the contactless interaction of electric vehicles with the power grid and has a promising prospect, but it may also bring about potential challenges to the power grid such as reliability deterioration. Electric buses serve as the forerunner to use this new charging mode due to their fixed driving patterns. Thus, it is needed to investigate its potential impact on power distribution system reliability. In this paper, first, the electric bus dynamic charging model is constructed, and then the impacts of this model on power distribution system reliability are studied. Simulation results indicate that compared with the non-dynamic charging mode, the electric bus dynamic charging mode does not cause additional deterioration to the reliability performance and has a slightly better effect. (C) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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