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  • 1.
    Ahmed, Amber
    et al.
    Vattenfall R&D, Stockholm, Sweden.
    Etherden, Nicholas
    Vattenfall R&D, Stockholm, Sweden.
    The potential for balancing the Swedish power grid with residential home batteries2021Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, Institution of Engineering and Technology, 2021, s. 2104-2108, artikel-id 0713Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the potential for prosumer batteries coupled to PV units to cover the national frequency balancing needs in Sweden. PV coupled residential batteries are found to be profitable with today's prices, if granted access to balancing markets. Simulations are based on national targets for solar PV production in 2040 (5-10 TWh, 5-10% of electric consumption) and current residential PV share of total installed PV capacity. In the study battery attachment rate was 50% and 15% of single family houses were equipped with 10 kW PV installation with a battery capacity of 6 kW / 7.68 kWh. In total, the battery PV systems constituted 25% of total installed capacity of PV in 2040. The results showed that 20% of the aggregated batteries capacity is sufficient to provide around 70-100% of each of the frequency reserves individually. The highest savings are gained for the households when both the primary frequency reserves, FCR-N and FCR-D, are provided by the aggregated batteries together with increasing the PV self-consumption, peak shaving and energy arbitrage. When providing frequency support the PV system payback time was reduced from 14 to 11 years when equipped with battery, compared to only installing PV.

  • 2.
    Alam, Md Tabrez
    et al.
    Energy & Thermofluids Lab Department of Chemical and Biochemical Engineering Indian Institute of Technology Patna Amhara Road, Bihta Patna 801106, Bihar, India.
    Raj, Aashna
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Singh, Lalan K.
    Energy & Thermofluids Lab Department of Chemical and Biochemical Engineering Indian Institute of Technology Patna Amhara Road, Bihta Patna 801106, Bihar, India.
    Gupta, Anoop K.
    Energy & Thermofluids Lab Department of Chemical and Biochemical Engineering Indian Institute of Technology Patna Amhara Road, Bihta Patna 801106, Bihar, India.
    A comparative analysis on charging performance of triplex-tube heat exchanger under various configurations of composite phase change material2024Ingår i: Thermal Science and Engineering Progress, E-ISSN 2451-9049, Vol. 51, artikel-id 102655Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In present work, the melting performance of triplex-tube latent heat thermal energy storage (LHTES) unit was numerically studied using equal volumes of PCM and metal foam composite PCM (CPCM) in various arrangements. For the n-eicosane (as PCM), the study was conducted at the fixed Rayleigh number (Ra) = 4.08x107, Prandtl number (Pr) = 62.9, and Stefan number (Ste) = 0.14. The results showed that positioning the metal foam on the bottom side and distributing segmented CPCM with alternating PCM zones effectively improved the system performance. Moreover, this also prevents the overheating of thermal layers in the LHTES unit. While the model labelled M2 exhibited the highest economic efficiency among all isotropic models, its low dimensionless thermal energy storage (TES) density (i.e., q’ ∼ 0.6) led this study to focus on models falling under the category having a TES density of ∼ 0.8. Compared to a pure PCM model, the configurations under equal volume ratio category demonstrated up to ∼ four times higher TES rate (p’) and the significant reduction of ∼ 75 % in melting time. The optimized isotropic model achieved the highest TES rate per unit cost with peak value of ∼ 3 at a price ratio (N) of 1. Lastly, the testing of metal foam anisotropy on the chosen design showed a substantial increase in melting/heat storage rates. The largest drop of ∼ 33 % in the total melting time was noticed for model M2 as compared to isotropic case.

  • 3.
    Alenius, Christoffer
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Dynamic simulation and techno-economicevaluation of a seasonally insulated hybridgreenhouse concept for subarctic climates2023Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The Swedish authority for social protection and preparedness, MSB, believes that the self-sufficiency of the country must be strengthened in order to be prepared for a crisis. Presently, Sweden is only 50% self-sufficientwhich is very low compared to its neighboring countries; and it is worse the further north you go. One solution could be to increase the production of food, for example vegetables, but the number of greenhouse operations in Sweden are already dwindling due to the inhospitable climate, which makes it expensive to keep up all-year cultivations. Norrbotten, the northernmost part of Sweden, has the highest heat demand for greenhouses in the country. One option could be to set up operation in heavily insulated buildings and rely on artificial lighting, in so called plant factories. Though, these are expensive, electricity intensive and have generally lower yields.

    This report will cover the development, validation, and performance of a dynamic model of a new greenhouse concept, developed for subarctic climates. The greenhouse is meant to utilize the strengths of both glass houses and plant factories to optimize the profits for a year-round operation. This, to find an alternative solution to the self-sufficiency problem in the winter. In addition to this, the optimal glaze for the climate shell had to be determined and what type of lighting technology would be the most viable. The hybrid greenhouse is a gableroof greenhouse with insulated north, west and east walls designed for microgreen cultivation, Lactuca Sativa. The interesting part of the greenhouse is that it has a retractable insulation cover, of mineral wool, inside of the climate shell. This was meant to heavily insulate the greenhouse during the winter seasons, though it would not let any sunlight in. This meant that the hybrid greenhouse must rely on artificial lighting in the winter but will get a reduced heating demand. When the outdoor temperature rises and the sun becomes more visible,the cover can be retracted to utilize sunlight for heating and photosynthesis. The cost between heating and electricity usage and the profits from the amount of yield will therefore vary depending on how long the coveris opened or closed and an optimal cost solution should be found somewhere within that variation. The model was created using Simulink version 10.6, which could simulate the heat demand, the humidity level, CO2-concentration, and the yield of the greenhouse.

    The models heat demand and yield was validated againsta greenhouse in Nikkala, Sweden, owned by Norrskenstomater. The model produced a standard deviation of 24.6 MWh over three months but it overestimated the yearly yield of Norrskenstomater with about 40%. To make the sure the hybrid greenhouse performed effectively, the amount of leakage must be minimized, as this has a significant impact on the heat demand. The hybrid greenhouse needs lighting alternatives with substantial active cooling (90% of the lamps input power), such as light emitting diodes. High pressure sodium lamps produce too much heat and can not be used at all. For yearly simulations, the cover was set to close for certain amounts of months during the year. The highest yearly profit, highest net present value (4.8 MSEK) and lowest payback time (3.5 years) could be achieved if the cover were closed between October and March. The best glazing material in terms of economic performance was 4 mm glass followed by 16 mm plastic panels in acrylic. The hybrid greenhouse could even outperform a greenhouse that did not cultivate during the winter. The hybrid greenhouse seems to get rid of the negative impacts of winter cultivation and is therefore considereda viable alternative as a cultivation system for subarctic climates. 

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  • 4.
    Ali, Salamat
    et al.
    School of Materials and Energy, Lanzhou University, Lanzhou 730000, China.
    Ahmad, Awais
    Department of Chemistry, The University of Lahore, Lahore, 54590, Pakistan; Departamento de Química Orgánica, Universidad de Córdoba, Campus Universitario de Rabanales, Edificio Marie Curie (C3), E-14014 Córdoba, Spain.
    Hussain, Iftikhar
    Department of Mechanical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong.
    Shah, Syed Shoaib Ahmad
    Department of Chemistry, School of Natural Sciences, National University of Sciences and Technology, Islamabad 44000, Pakistan.
    Ali, Shafqat
    Department of Physics, Shah Abdul Latif University Khairpur, Khairpur, Sindh, 66202, Pakistan.
    Ali, Asad
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Javed, Muhammad Sufyan
    Department of Chemistry, The University of Lahore, Lahore, 54590, Pakistan; School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China.
    Experimental and Theoretical Aspects of MXenes-Based Energy Storage and Energy Conversion Devices2023Ingår i: Journal of Chemistry and Environment, E-ISSN 2959-0132, Vol. 2, nr 2, s. 54-81Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Transition metal carbides, nitrides, and carbonitrides (MXenes) have become an appealing framework for developing various energy applications. MXenes with van der Waals (vdW) interactions are facile, highly efficient, affordable, and self-assembled features that improve energy density. MXenes exhibit large surface area, high electric conductivity, and excellent electrochemical characteristics for various energy applications. This review summarizes and emphasizes the current developments in MXene with improved performance for energy storage or conversion devices, including supercapacitors (SCs), various types of rechargeable batteries (RBs), solar cells, and fuel cells. We discuss the crystal structures of MXenes properties of MXenes and briefly discuss them for different types of energy applications. Finally, the critical outlook and perspective for the MXene progress for applications in energy applications are also described.

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  • 5.
    Bagheri, Marzieh
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Integrated sewage sludge treatment scenarios – techno-economic analysis on energy and phosphorus recovery2022Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Sewage sludge is a by-product of wastewater treatment that simultaneously gathers contaminants, valuable organic matter, and nutrients. The treatment of the increasing amount of sewage sludge is important from both pollution prevention and resource recovery perspectives as i) large shares of mineral phosphorus, listed as a critical raw material, terminate in the sewage sludge, and ii) energy recovery from sewage sludge can cover the energy-intensive demand of the treatment process. Previous research has identified sewage sludge combustion as a suitable treatment approach as it both addresses contaminant destruction and paves the way for efficient phosphorus recovery from the sewage sludge ash. The commercial development of this practice has, however, been slow. Therefore, this thesis aims to investigate the challenges in sustainable sewage sludge management, and to, in more detail, identify the economic viability of energy and phosphorus recovery from sewage sludge through combustion.

    The thesis’ aim is divided into two objectives addressed in three papers. First, to investigate how different aspects of sewage sludge management, such as contaminants, economic efficiency, technical aspects, and legislation, evolve and interact. This has been done by a review of sewage sludge management research over fifty years (Paper I). Second, to investigate the economic viability of simultaneous energy and phosphorus recovery from sewage sludge by comparing different technology and market scenarios. This has been done for i) new sewage sludge mono-/co-combustion plants (Paper II), and ii) the integration of treatment technologies, mainly anaerobic digestion, hydrothermal carbonization, and combustion, in an existing wastewater treatment plant (Paper III). 

    Results from the analysis of sewage sludge management research (Paper I) show a narrow-focused perspective that often excludes inseparable aspects such as combination of economic consideration and advanced extraction technology. The investment viability of a new mono-/co-combustion of sewage sludge (Paper II) is highly conditional on heat, electricity, and fertilizer price, and external financial support is often a crucial requirement. Sewage sludge co-combustion with potassium-rich biomasses improves sewage sludge quality and forms usable ash as fertilizer without further need for phosphorus recovery technology. In this case, the economic feasibility of the process is independent of usable ash revenue, which stimulates a competitive selling price for the ash, thereby improving the marketing of sludge-based fertilizer. Avoided disposal costs of sewage sludge for a retrofitted wastewater treatment plant by introducing hydrothermal carbonization (Paper III) shows good economic feasibility while recovering phosphorus. Integrating anaerobic digestion, hydrothermal carbonization, and combustion may also improve investment incentives by improving energy outputs and phosphorus recovery. The economic feasibility is contingent on product (hydrochar, heat, electricity) prices and sensitive to added equipment costs, and costs for sludge transportation and disposal. 

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  • 6.
    Bagheri, Marzieh
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Sewage Sludge Treatment Scenarios: Techno-Economic Analyses of Energy and Phosphorus Recovery Focusing on Implementation Challenges2024Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Managing sewage sludge, an inevitable by-product of wastewater treatment processes rich in both contaminants and valuable resources, presents a dual challenge: ensuring pollution prevention by immobilizing or destroying contaminants, and facilitating resource recovery. Balancing these objectives is critical given the growing volumes of sewage sludge and the imperative to both protect the environment and recover valuable resources. The unknown risks of land application of sludge, the currently most common disposal method, make thermal conversion a promising alternative, as it enables energy recovery, the breakdown of potentially harmful organic compounds, and the formation of volume-reduced, sanitized products. Despite the technical feasibility, the commercial development of advanced recovery technologies has been slow. 

    This thesis aims to expand knowledge on different sewage sludge treatment and disposal scenarios under varying conditions; thereby shedding light on implementation challenges, local opportunities, and the financial dynamics critical for phosphorus and energy recovery from the perspectives of wastewater treatment plants, investors, and policymakers. The aim is primarily addressed by performing techno-economic analysis of sewage sludge treatment scenarios, covering the entire sludge treatment process from sludge treatment to end products and disposal (Paper II-V). The techno-economic analysis is supplemented by a review of academic research on sewage sludge management from 1971 to 2019 (Paper I). 

    Results from the analysis of sewage sludge management research (Paper I) show a narrow-focused perspective that often misses the broader, interconnected aspects of sewage sludge management, leading to research that, while detailed, fails to capture the complexity of the field. The investment viability of a new mono-/co-combustion plant for sewage sludge (Paper II) is highly conditional on heat, electricity, and fertilizer prices, and external financial support is often a crucial requirement. Cocombustion of sludge (in low ratios) with K-rich agricultural biomass requirement in and energy demand of a thermal dryer, and by yielding ash that contains phosphorus in a plant-available form. Utilizing existing heat facility (Paper III) and co-combustion to mitigate investment costs and energy demand in sludge management showed the potential to offer a cost-effective alternative to land application. However, the viability of co-combustion hinges on both a high heat market price (Paper II) and the proximity of affordable biomass resources (Paper III). Without these conditions, co-combustion may increase the financial burden of sludge management on wastewater treatment plants and policymakers. 

    Retrofitting a wastewater treatment plant by integrating hydrothermal carbonization in sludge treatment (Paper IV), demonstrated good economic feasibility, primarily due to the avoided disposal costs, while also recovering phosphorus. However, integrating hydrothermal carbonization in a system designed for a thermal dryer may cause a significant reduction in electricity production.

    Given the high moisture content of sludge and the low market prices for fertilizer, the potential revenue from energy and phosphorus recovery is inadequate to solely drive investment in advanced sewage sludge treatment technologies (Papers II-V). This issue is exacerbated by the fact that most wastewater treatment plants are small in scale. Collaborative sludge management across neighboring wastewater treatment plants (Paper V) increases phosphorus recovery capacity and leverages economies of scale, fostering investment in advanced technology. This strategy presents a significant opportunity to lower the treatment costs and offers a competitive alternative to land application, while encompassing energy and phosphorus recovery into the sludge treatment.

    In conclusion, resource recovery and pollution prevention in sludge management is a complex task that necessitates simultaneous consideration of technical aspects, product quality, site-specific conditions, and profitability to ensure a comprehensive and viable approach. Leveraging local infrastructure and resources in sewage sludge management is crucial, highlighting the ecessity for strategies to be tailored to the local opportunities and limitations. Such an approach outperforms mono-combustion by eliminating the investment ensures that solutions are not only environmentally sustainable but also economically viable and socially acceptable. 

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  • 7.
    Bagheri, Marzieh
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bauer, Torben
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ekman Burgman, Linus
    Department of Thematic Studies, Technology and Social Change at Linköping University, 58183, Linköping, Sweden.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Fifty years of sewage sludge management research: Mapping researchers' motivations and concerns2023Ingår i: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 325, artikel-id 116412Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sewage sludge management is torn between a desire for pollution prevention and reuse of a valuable resource. Reconciling these interests in sustainable management is a challenge for researchers. This study focuses on how research on sewage sludge management practices has evolved and scrutinizes how this research is interlinked with concerns and societal issues such as contaminants, economic efficiency, and legislation. Based on published academic papers on sewage sludge management between 1971 and 2019, this study found four trends in research focused on sewage sludge management: a decreasing interest in disposal (landfilling and sea dumping), a dominant interest in land application, a growing interest in sewage sludge as product, and a stable interest in energy recovery. Research on disposal focuses on increasing sludge volumes, legislative changes, and economic challenges with an interest in waste co-treatment. Research on land application concerns nutrient use and contaminants, mainly heavy metals. Research on sewage sludge as a product focuses on the extraction of certain resources and less on use of sewage sludge specifically. Research on energy recovery of sewage sludge focuses on volume reduction rather than contaminants. Two-thirds of the papers are detailed studies aiming to improve single technologies and assessing single risks or benefits. As management of sewage sludge is multifaceted, the narrow focus resulting from detailed studies promotes some concerns while excluding others. Therefore, this study highlights potential gaps such as the combination of nutrient use and disposal and energy recovery and nutrient use. 

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  • 8.
    Bagheri, Marzieh
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Introducing hydrothermal carbonization to sewage sludge treatment systems—a way of improving energy recovery and economic performance?2023Ingår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 170, s. 131-143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrothermal carbonization (HTC) can mitigate the disposal costs of sewage sludge in a wastewater treatment plant. This study analyzes the impact of integrating HTC with anaerobic digestion (AD) and combustion from a combined energy and economic performance perspective. Net energy balance and investment opportunity are investigated for a number of technical scenarios considering i) different combinations of the technologies: AD + HTC, AD + thermal dryer + combustion, and AD + HTC + combustion, ii) different options for HTC process water treatment: wet oxidation (WO) + AD, and direct return to AD, and iii) different products: heat-only, heat and electricity, hydrochar, and phosphorus.

    The results show trade-offs between investment cost, self-supplement of heat, and output electricity when WO is used. In AD + HTC, net heat output decreases compared to the reference plant, but avoided disposal costs and hydrochar revenue result in profitable investment when the process water is directly returned to the AD. Although HTC has a lower heat demand than the thermal dryer, replacing the thermal dryer with HTC is only possible when AD, HTC, and combustion are connected, or when WO covers HTC’s heat demand. HTC may impair the electricity production because of the necessity for a high-temperature heat source, whereas the thermal dryer can utilize a low-temperature heat source. In conclusion, energy advantages of HTC in AD + HTC + combustion are insufficient to provide a promising investment opportunity due to high investment costs of HTC. The investment opportunity improves by co-combustion of hydrochar and external sludge.

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  • 9.
    Bagheri, Marzieh
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Öhman, Marcus
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Economic viability of co-combusting sewage sludge with agricultural biomasses: a resource-efficient strategy for sludge treatment and phosphorus recovery in SwedenManuskript (preprint) (Övrigt vetenskapligt)
  • 10.
    Bagheri, Marzieh
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Techno-Economic Analysis of Scenarios on Energy and Phosphorus Recovery from Mono- and Co-Combustion of Municipal Sewage Sludge2022Ingår i: Sustainability, E-ISSN 2071-1050, Vol. 14, nr 5, artikel-id 2603Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study evaluates the techno-economic feasibility of energy and phosphorus (P) fertilizer (PF) recovery from municipal sewage sludge (MSS) through incineration in new combustion plants. We evaluated the economic impact of five critical process design choices: (1) boiler type, (2) fuel (MSS mono-combustion/co-combustion with wheat straw), (3) production scale (10/100 MW), (4) products (heat, electricity, PF), and (5) ash destination. Aspen Plus modeling provided mass and energy balances of each technology scenario. The economic feasibility was evaluated by calculating the minimum selling price of the products, as well as the MSS gate fees required to reach profitability. The dependency on key boundary conditions (operating time, market prices, policy support) was also evaluated. The results showed a significant dependency on both energy and fertilizer market prices and on financial support in the form of an MSS gate fee. Heat was preferred over combined heat and power (CHP), which was feasible only on the largest scale (100 MW) at maximum annual operating time (8000 h/y). Co-combustion showed lower heat recovery cost (19–30 €/MWh) than mono-combustion (29–66 €/MWh) due to 25–35% lower energy demand and 17–25% higher fuel heating value. Co-combustion also showed promising performance for P recovery, as PF could be recovered without ash post-treatment and sold at a competitive price, and co-combustion could be applicable also in smaller cities. When implementing ash post-treatment, the final cost of ash-based PF was more than four times the price of commercial PF. In conclusion, investment in a new combustion plant for MSS treatment appears conditional to gate fees unless the boundary conditions would change significantly.

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  • 11.
    Bakhtiari, Hamed
    et al.
    Electrical Engineering Department, Hamedan University of Technology, Mardom Street, Shahid Fahmideh Boulevard, Hamedan, Iran.
    Naghizadeh, Ramezan Ali
    Electrical Engineering Department, Hamedan University of Technology, Mardom Street, Shahid Fahmideh Boulevard, Hamedan, Iran.
    Multi-criteria optimal sizing of hybrid renewable energy systems including wind, photovoltaic, battery, and hydrogen storage with ɛ-constraint method2018Ingår i: IET Renewable Power Generation, ISSN 1752-1416, E-ISSN 1752-1424, Vol. 12, s. 883-892Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hybrid renewable energy systems (HRES) should be designed appropriately with an adequate combination of different renewable sources and various energy storage methods to overcome the problem of intermittency of renewable energy resources. A multi-criteria approach is proposed in this study to design an HRES including wind turbine, photovoltaic panels, fuel cell, electrolyser, hydrogen tank, and battery storage unit with an intermittent load. Three design criteria including loss of power supply probability, total energy loss (TEL), and the power difference between generation and storing capacity (as TELSUB) are taken into account in minimising the total cost of the system considering the interest rate and lifetime. The justifications and advantages of using these criteria are thoroughly discussed along with appropriate presentation of the results. The purpose of considering TEL and TELSUB is discussed thoroughly. The ɛ-constraint method is used to handle practical constraints of the proposed multi-criteria problem to construct a multi-objective fitness function. Shuffled frog leaping algorithm is implemented to achieve better optimal results. The proposed approach is implemented using real wind speed and solar irradiance data for a specific location with an intermittent load demand. The results verify performance of the proposed multi-criteria design procedure.

  • 12.
    Bakhtiari, Hamed
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Zhong, Jin
    University of Hong Kong, Hong Kong.
    Alvarez, Manuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Risk-Averse Pricing Strategy for Demand ResponseManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Interruptible/curtailable demand response program (ICDRP) is a valuable ancillary service resource in electricity markets. Due to the uncertainty of customer behavior in a market, risk-based pricing for ICDRP is needed. It is also necessary to evaluate the eligibility conditions for utilizing uncertain ICDRP as an ancillary service. In this paper, we first propose a pricing strategy that allocates payoffs to the coalition of ICDRP participants considering risk management costs caused by the uncertain responsiveness of ICDRP participants while maximizing the system operator’s ability to cope with uncertainties and optimizing generation outputs and regulation price in the frequency regulation market. Then, we investigate the flexibility of predetermined reserves in the forward electricity market as an eligibility condition for risk-averse utilization of ICDRP. A risk-averse Shapley value method is developed in the proposed pricing strategy. Finally, we carry out numerical studies to illustrate the feasibility and effectiveness of the proposed pricing strategy to determine the incentives and penalties in a fair way. We also demonstrate the necessity of considering the uncertainties of ICDRP responsiveness in the required reserve selection process to successfully exploit the benefits of ICDRP in the frequency regulation market.

  • 13.
    Bakhtiari, Hamed
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Zhong, Jin
    The University of Hong Kong, Hong Kong.
    Alvarez, Manuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    The Utilization of Demand Response Programs In Renewable-based Microgrids: Benefits and Challenges2021Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, Institution of Engineering and Technology, 2021, s. 2999-3003, artikel-id 0213Konferensbidrag (Refereegranskat)
  • 14.
    Bauer, Torben
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Sustainable Sewage Sludge Management: Addressing Multidisciplinary Challenges2023Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This PhD thesis focuses on multidisciplinary challenges in sewage sludge management and how they can be addressed to increase sustainability. 

    Sewage sludge is the residual from wastewater treatment. It contains both resources and contaminants making its management challenging. In the past sewage sludge was often used as a fertilizer in agriculture, a practice that is still used in several countries. Today, this practice gets questioned in Europe and especially in Sweden due to the presence of contaminants in the sludge. At the same time, the resources in the sludge get into a stronger focus as society moves towards a circular economy and food production should get more resilient in a world with geopolitical challenges. In sustainable sewage sludge management, the two goals of immobilising/destroying the contaminants and utilizing the resources in the sludge are combined. 

    This thesis identifies challenges in various disciplines and provides potential solutions to make sewage sludge management more sustainable. The discussed challenges cover the following areas: legislation (EU and Sweden), perception of sewage sludge (Sweden), research on sewage sludge management (international), and combinations of treatment methods. Results show that outdated legislation in Sweden creates insecurities, while the negative perception of sewage sludge in Swedish society further aggravates these insecurities. Although technical solutions are available or under development, e.g., treatment combinations that can separate resources and contaminants, actors in Sweden remain hesitant due to the aforementioned insecurities. This thesis emphasizes that interdisciplinary approaches, and dialogues between different actor groups and society are essential. The multitude of challenges requires solutions that combine technical and non-technical approaches. Therefore, this thesis provides recommendations for more sustainable sewage sludge management practices, including updating legislation.

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  • 15.
    Bhatt, Puja
    et al.
    Central Department of Biotechnology, Tribhuvan University, Kirtipur 44618, Nepal.
    Poudyal, Pranita
    Central Department of Biotechnology, Tribhuvan University, Kirtipur 44618, Nepal.
    Dhungana, Pradip
    Central Department of Biotechnology, Tribhuvan University, Kirtipur 44618, Nepal.
    Prajapati, Bikram
    Central Department of Biotechnology, Tribhuvan University, Kirtipur 44618, Nepal.
    Bajracharya, Suman
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Yadav, Amar Prasad
    Central Department of Chemistry, Tribhuvan University, Kirtipur 44618, Nepal.
    Bhattarai, Tribikram
    Central Department of Biotechnology, Tribhuvan University, Kirtipur 44618, Nepal.
    Sreerama, Lakshmaiah
    Central Department of Biotechnology, Tribhuvan University, Kirtipur 44618, Nepal; Department of Chemistry and Biochemistry, St. Cloud State University, St. Cloud, MN 56301, USA.
    Joshi, Jarina
    Central Department of Biotechnology, Tribhuvan University, Kirtipur 44618, Nepal.
    Enhancement of Biogas (Methane) Production from Cow Dung Using a Microbial Electrochemical Cell and Molecular Characterization of Isolated Methanogenic Bacteria2024Ingår i: Biomass, E-ISSN 2673-8783, Vol. 4, nr 2, s. 455-471Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biogas has long been used as a household cooking fuel in many tropical counties, and it has the potential to be a significant energy source beyond household cooking fuel. In this study, we describe the use of low electrical energy input in an anaerobic digestion process using a microbial electrochemical cell (MEC) to promote methane content in biogas at 18, 28, and 37 °C. Although the maximum amount of biogas production was at 37 °C (25 cm3), biogas could be effectively produced at lower temperatures, i.e., 18 (13 cm3) and 28 °C (19 cm3), with an external 2 V power input. The biogas production of 13 cm3 obtained at 18 °C was ~65-fold higher than the biogas produced without an external power supply (0.2 cm3). This was further enhanced by 23% using carbon-nanotubes-treated (CNT) graphite electrodes. This suggests that the MEC can be operated at as low as 18 °C and still produce significant amounts of biogas. The share of CH4 in biogas produced in the controls was 30%, whereas the biogas produced in an MEC had 80% CH4. The MEC effectively reduced COD to 42%, whereas it consumed 98% of reducing sugars. Accordingly, it is a suitable method for waste/manure treatment. Molecular characterization using 16s rRNA sequencing confirmed the presence of methanogenic bacteria, viz., Serratia liquefaciens and Zoballella taiwanensis, in the inoculum used for the fermentation. Consistent with recent studies, we believe that electromethanogenesis will play a significant role in the production of value-added products and improve the management of waste by converting it to energy.

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  • 16.
    Bollen, Math H.J.
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Moreno-Munoz, Antonio
    Universidad de Córdoba, Córdoba, Spain.
    The power grid as part of a 100% renewable energy system2017Ingår i: Large Scale Grid Integration of Renewable Energy Sources / [ed] Antonio Moreno-Munoz, Institution of Engineering and Technology , 2017, s. 1-27Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 17.
    Brännvall, Rickard
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB. RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Mattson, Louise
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Lundmark, Erik
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Vesterlund, Mattias
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Data Center Excess Heat Recovery: A Case Study of Apple Drying2020Ingår i: ECOS 2020: Proceedings of the 33rd International Conference on Efficiency, Cost, Optimization, Simulation and Enviromental Impact of Energy Systems / [ed] Ryohei Yokoyama, Yoshiharu Amano, ECOS 2020 Local Organizing Committee , 2020, s. 2165-2174Konferensbidrag (Refereegranskat)
    Abstract [en]

    Finding synergies between heat producing and heat consuming actors in an economy provides opportunity for more efficient energy utilization and reduction of overall power consumption. We propose to use low-grade heat recovered from data centers directly in food processing industries, for example for the drying of fruit and berries. This study analyses how the heat output of industrial IT-load on servers can dry apples in a small-scale experimental set up.To keep the temperatures of the server exhaust airflow near a desired set-point we use a model predictive controller (MPC) re-purposed to the drying experiment set-up from a previous work that used machine learning models for cluster thermal management. Thus, conditions with for example 37 C for 8 hours drying can be obtained with results very similar to conventional drying of apples.The proposed solution increases the value output of the electricity used in a data center by capturing and using the excess heat that would otherwise be exhausted. The results from our experiments show that drying foods with excess heat from data center is possible with potential of strengthening the food processing industry and contribute to food self-sufficiency in northern Sweden.

  • 18.
    Carlsson, Isak
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Kartläggning och energieffektivisering: KV61, Gärstadverket Linköping2019Självständigt arbete på grundnivå (yrkesexamen), 180 hpStudentuppsats (Examensarbete)
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  • 19.
    Carvalho, Lara
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Opportunities to broaden biomass feedstocks in thermochemical conversion technologies2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Global environmental concerns are motivating a growing interest in broadening the biomass feedstock base in several energy sectors, including (i) the domestic heating sector, presently dominated by stem wood combustion, and (ii) biofuel production, presently dominated by edible crops. The objective of this thesis is to investigate new opportunities to broaden the biomass feedstock in thermochemical conversion technologies. The performance of different feedstocks was therefore investigated for (i) heat production in small-scale combustion systems and (ii) biofuel production in large-scale gasification-based plants. The selected feedstocks were agricultural residues, forest wood, pyrolysis liquid and industrial by-products, such as lignin, black liquor, crude glycerol and fermentation residues.

    The alkali metals content in biomass has an important role in combustion and gasification. Alkali metals can cause ash-related problems in small-scale combustion systems, while they can catalyse gasification reactions thus increasing conversion efficiency. Keeping this effect in mind, the present investigation was based on combustion tests with pelletised agricultural residues (non-woody feedstocks with ash contents of 3-8 wt% on a dry basis) to evaluate their combustion feasibility in several small-scale appliances. Moreover, the potential techno-economic benefits of alkali addition in gasification-based biofuel plants were investigated in two different systems: (i) stand-alone biofuel plant operated with wet-alkali-impregnated forest residues and alkali-rich lignin as well as (ii) biofuel plant integrated with a Kraft pulp mill operated with black liquor (an inherently alkali-rich feedstock) mixed with different blend ratios of pyrolysis liquid, crude glycerol or fermentation residues (co-gasification concept). The techno-economic analysis in large-scale entrained-flow-gasification-based biofuel plants was made with the help of simulation tools.

    The combustion tests have shown that high alkali feedstocks lead to problems with ash accumulation and slag formation in small-scale appliances. The results indicated that non-woody feedstocks can only be burned in appliances adapted to manage high ash content feedstocks. Effective ash cleaning and enhanced combustion controlling mechanisms are relevant characteristics to have in appliances when using these feedstocks. It has been shown that four out of the seven selected feedstocks can be burned in small-scale appliances, while fulfilling the legal European requirements (EN 303-5:2012) in terms of combustion efficiency and emissions. The nitrogen content and ash composition were shown to be important parameters to evaluate whether a feedstock can be utilised in small-scale combustion appliances.

    The techno-economic investigations of the gasification-based biofuel plants have shown that alkali impregnation is an attractive option to increase energy performance and downstream biofuel production. The economic assessment has indicated that alkali impregnation does not significantly increase biofuel production costs, while it allows the application of a new syngas cleaning system that can significantly reduce biofuel production costs. The present study has shown that the vi co-gasification concept has also techno-economic benefits as a result of the (i) alkali content in black liquor and (ii) economy-of-scale effects. These benefits can be enhanced by choosing energy-rich and low-cost blend-in feedstocks. The gasification-based biofuel production routes hereby investigated exhibit a good economic performance since biofuel required selling prices were economically competitive with other biofuel production routes as well as with taxed gasoline.

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  • 20.
    Carvalho, Lara
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Furusjö, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. IVL – Swedish Environmental Institute, Stockholm, Sweden.
    Ma, Chunyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Öhrman, Olov G. W.
    IVL – Swedish Environmental Institute, Stockholm, Sweden;RISE Energy Technology Center AB, Piteå, Sweden.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Alkali enhanced biomass gasification with in situ S capture and a novel syngas cleaning: Part 2: Techno-economic analysis2018Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 165, nr Part B, s. 471-482Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Previous research has shown that alkali addition has operational advantages in entrained flow biomass gasification and allows for capture of up to 90% of the biomass sulfur in the slag phase. The resultant low-sulfur content syngas can create new possibilities for syngas cleaning processes. The aim was to assess the techno-economic performance of biofuel production via gasification of alkali impregnated biomass using a novel gas cleaning systemcomprised of (i) entrained flow catalytic gasification with in situ sulfur removal, (ii) further sulfur removal using a zinc bed, (iii) tar removal using a carbon filter, and (iv) CO2 reductionwith zeolite membranes, in comparison to the expensive acid gas removal system (Rectisol technology). The results show that alkali impregnation increases methanol productionallowing for selling prices similar to biofuel production from non-impregnated biomass. It was concluded that the methanol production using the novel cleaning system is comparable to the Rectisol technology in terms of energy efficiency, while showing an economic advantagederived from a methanol selling price reduction of 2–6 €/MWh. The results showed a high level of robustness to changes related to prices and operation. Methanol selling prices could be further reduced by choosing low sulfur content feedstocks.

  • 21.
    Carvalho, Lara
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wolf, Jens
    RISE Bioeconomy.
    Furusjö, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Methanol production via black liquor co-gasification with expanded raw material base: Techno-economic assessment2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 225, s. 570-584Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Entrained flow gasification of black liquor combined with downstream-gas-derived synthesis of biofuels in Kraft pulp mills has shown advantages regarding energy efficiency and economic performance when compared to combustion in a recovery boiler. To further increase the operation flexibility and the profitability of the biofuel plant while at the same time increase biofuel production, black liquor can be co-gasified with a secondary feedstock (blend-in feedstock). This work has evaluated the prospects of producing biofuels via co-gasification of black liquor and different blend-in feedstocks (crude glycerol, fermentation residues, pyrolysis liquids) at different blend ratios. Process modelling tools were used, in combination with techno-economic assessment methods. Two methanol grades, crude and grade AA methanol, were investigated. The results showed that the co-gasification concepts resulted in significant increases in methanol production volumes, as well as in improved conversion efficiencies, when compared with black liquor gasification; 5-11 and 4-10 percentage point in terms of cold gas efficiency and methanol conversion efficiency, respectively. The economic analysis showed that required methanol selling prices ranging from 55-101 €/MWh for crude methanol and 58-104 €/MWh for grade AA methanol were obtained for an IRR of 15%. Blend-in led to positive economies-of-scale effects and subsequently decreased required methanol selling prices, in particular for low cost blend-in feedstocks (prices below approximately 20 €/MWh). The co-gasification concepts showed economic competitiveness to other biofuel production routes. When compared with fossil fuels, the resulting crude methanol selling prices were above maritime gas oil prices. Nonetheless, for fossil derived methanol prices higher than 80 €/MWh, crude methanol from co-gasification could be an economically competitive option. Grade AA methanol could also compete with taxed gasoline. Crude glycerol turned out as the most attractive blend-in feedstock, from an economic perspective. When mixed with black liquor in a ratio of 50/50, grade AA methanol could even be cost competitive with untaxed gasoline.

  • 22.
    Chen, Jingjing
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Heat-transfer Enhancement for Slurries from Biogas Plants− Properties, processes, and thermal systems2022Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

     Biomethane production from renewable residues with anaerobic digestion gains increasing attention as a crucial alternative to petroleum fuels. It has been vigorously developed, but the large amounts of subsidy from the government indicate that the process efficiency needs to be further improved. For biomethane production, on the one hand, a great amount of heat needs to be used for heating the feeding slurry, sanitation of slurry, and maintaining the temperature in the large-scale reactors. On the other hand, a large amount of thermophilic effluent slurries brings a huge amount of waste heat, which can be recovered. This makes it important to study how to increase production by improving the thermal efficiency of biogas plants with novel heat exchangers. 

    The working fluids in the biogas plants are the non-Newtonian and high-viscous slurries, and the conventional heat exchangers in biogas plants always show much lower performance compared to those in other industries. Normally, the slurries in the biogas plant consist of different substrates, including straw, manure, food waste, municipal sludge, and their mixtures, and various factors such as the amount and type of solids, particle size, shear rate, and temperature impact the rheological properties of the slurries, which makes the complexity in the rheological properties and the difficulty in developing novel heat exchangers.

    The development of heat exchangers calls for the rheological properties of slurries. However, to the best of our knowledge, only the rheology of manure slurry was systematically determined and modeled considering the effect of temperature. The lack of the rheological properties of slurries further hinders the design and development of novel geometries to enhance the heat transfer of the slurries. Correspondingly, the quantitative contribution and potential of the waste-heat recovery from the slurries to production using the enhanced geometry remain unclear. 

        In this thesis work, to design novel geometry with heat-transfer enhancement for different slurries and determine its potential in thermal cycles in the full-scale biogas plants, firstly, the temperature-dependent rheological properties of the slurries, including the corn straw, food waste, and mixed slurries, were tested and modeled. It was found that these slurries possess strong shear-thinning behavior, the temperature has a significant impact on their dynamic viscosity, and the power-law model combined with the Arrhenius equation can describe the rheology well.

        Subsequently, with the reliable models of the rheological properties as the key input,  Computational Fluid Dynamics simulations were conducted to screen different twisted geometries, determine the heat-transfer performance, and reveal the mechanism of the heat-transfer enhancement. Lab- and pilot-scale experiments were also conducted to validate the numerical results. The twisted hexagonal tubes show a positive enhancement factor up to 2.6 compared to normal heat exchangers in a wide range of operating conditions. The continuous and strong near-wall shear effect is the intrinsic reason for achieving a significant heat-transfer enhancement in the twisted hexagonal tubes. Moreover, the generalized engineering equations for predicting the effective shear rate and heat-transfer performance with measurable parameters were established and verified with both numerical and experimental results.

        Finally, the twisted-hexagonal-tube heat exchange was integrated with complete thermal cycles, including waste-heat recovery and external heating processes in the biogas plant, and the potential of increased production and profits were modeled and analyzed combined with the practical operating conditions in a full-scale biogas plant. It was found that for the waste-heat recovery using the twisted hexagonal tubes, the net raw biogas production can increase by up to 17.0 %, and for the external heating process, the increased profit equivalent to 39 % of total production can be achieved owing to energy conservation in external heating using the twisted-hexagonal-tube heat exchangers for a full-scale biogas plant. 

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  • 23.
    Chen, Jingjing
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Lu, Xiaohua
    State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Heat-transfer Enhancement with Pulsating Flow in Twisted Hexagonal Tube for Manure Slurry from Biogas Plants2020Ingår i: Proceedings of 12th International Conference on Applied Energy, 2020, Vol. 9, artikel-id 178Konferensbidrag (Refereegranskat)
    Abstract [en]

    Biogas is one of the most crucial renewable energy and achieving high-efficient heat exchangers is the key to improve its production. In this study, the effect of pulsating flow on heat transfer in a twisted hexagonal tube with manure slurry was investigated for the first time by using computational fluid dynamics CFD. The performances of pulsating flows were simulated under different conditions, including the inlet velocity, frequency, and amplitude of pulsating flow in the twisted hexagonal tube with different torques. Pressure drops at different frequencies were further investigated. Moreover, the mechanism of heat-transfer enhancement was revealed with the evolution of the heat-transfer coefficient over time. It was found the pulsating flow achieves an 18.9% enhancement at low torque.

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  • 24.
    Chirwa, Damaseck
    et al.
    Energy Regulation Board of Zambia, Copperbelt Region, Kitwe, Zambia.
    Goyal, Rahul
    Indian Institute of Technology Delhi, Department of Energy Science and Engineering, Delhi, India.
    Mulenga, Enock
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. School of Engineering, Copperbelt University, Kitwe, Zambia Division of Energy Science-Department of Engineering Sciences and Mathematics.
    Floating solar photovoltaic (FSPV) potential in Zambia: Case studies on six hydropower power plant reservoirs2023Ingår i: Renewable Energy Focus, ISSN 1755-0084, Vol. 44, s. 344-356Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study assesses the technical resource potential for floating solar photovoltaic systems on Zambia's existing hydro-based power plants. The research uses System Advisor Model (SAM) and has made some input changes to adapt the standard photovoltaic performance model to Floating Solar Photovoltaics. The input changes are the tilt angle and the losses. Tilt has been taken as 5o, while the soiling losses have been taken as zero (0). Zambia's theoretical maximum floating solar photovoltaic potential (100% coverage) was found to be 254.083 GWp. The floating solar photovoltaic potential in Zambia at 10% coverage is the best option. It was found to be 25.408 GWp, while the energy generated was 43,448.1212 GWh. Compared to the total installed electricity (3.011) GW, this power is 8 times more than the current installed capacity. Kariba dam shows the highest potential of 24.461 GWp, followed by Itezhi Tezhi (0.506 GWp), Kafue Gorge Upper (0.393 GWp), Mita Hills (0.0314) GWp, Mulungushi Dam (0.0131) GWp, and Kafue Gorge Lower (0.0043 GWp). The country has an average photovoltaics electricity daily output ranging from 4.54 to 4.85 kWh/kWp, which equates to 1658 to 1772 kWh/kWp totals. The findings of this study will increase public awareness of floating solar photovoltaic systems and It will allow the government and investors to consider investing in the technology. This shall ultimately increase power generation in Zambia, helping to alleviate the country's 0.81 GWp power deficit. The National Energy Policy facilitates the development and deployment of renewable and alternative energy sources like hydropower and solar photovoltaic power. Through this policy, an assessment of the resource potential for ground-mounted Solar photovoltaics has been conducted. The policy does not mention the new technology of floating solar photovoltaic systems, which benefits from an increased energy yield due to the cooling effect of water since it is located on the water's surface. Lower shading, decreased civil works, lower grid interconnection costs, reduced water evaporation, enhanced water quality, lowered algae blooming, and valuable land are released for other uses, such as agricultural land or residential developments, when existing water reservoirs are used. Some potential benefits come with the new technology, although it is still nascent.

  • 25.
    Collins, Gabriel
    et al.
    Mineral and Energy Economics Program, Colorado School of Mines, Golden, CO, USA; Payne Institute for Public Policy, Colorado School of Mines, Golden, CO, USA.
    Dahl, Carol A.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik, konst och samhälle, Samhällsvetenskap. Mineral and Energy Economics Program, Colorado School of Mines, Golden, CO, USA; Payne Institute for Public Policy, Colorado School of Mines, Golden, CO, USA.
    Fleming, Maxwell
    Mineral and Energy Economics Program, Colorado School of Mines, Golden, CO, USA; Payne Institute for Public Policy, Colorado School of Mines, Golden, CO, USA.
    Tanner, Michael
    Mineral and Energy Economics Program, Colorado School of Mines, Golden, CO, USA.
    Martin, Wilson C.
    Mineral and Energy Economics Program, Colorado School of Mines, Golden, CO, USA.
    Nadkarni, Kabir
    Payne Institute for Public Policy, Colorado School of Mines, Golden, CO, USA.
    Hastings-Simon, Sara
    Payne Institute for Public Policy, Colorado School of Mines, Golden, CO, USA; Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada; School of Public Policy, Sustainable Energy Development Program, University of Calgary, Calgary, AB, Canada.
    Bazilian, Morgan
    Payne Institute for Public Policy, Colorado School of Mines, Golden, CO, USA.
    Projecting demand for mineral-based critical materials in the energy transition for electricity2024Ingår i: Mineral Economics, ISSN 2191-2203, E-ISSN 2191-2211Artikel i tidskrift (Refereegranskat)
  • 26.
    Crafoord, Emelie
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Bark, Glenn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Wanhainen, Christina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Is the Swedish onshore bedrock suitable for carbon dioxidesequestration?2022Ingår i: Geological Society of Sweden, 150 year anniversary meeting: Abstract volume / [ed] Bergman Weihed, J.; Johansson, Å.; Rehnström, E., Geologiska Föreningen , 2022, s. 52-53Konferensbidrag (Övrigt vetenskapligt)
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  • 27.
    Dahmani, Abdennasser
    et al.
    Department of Mechanical Engineering, Faculty of Science and Technology, GIDD Industrial Engineering and Sustainable Development Laboratory, University of Relizane, Bourmadia, Relizane, 48000, Algeria.
    Ammi, Yamina
    Laboratory of Biomaterials and Transport Phenomena (LBMPT), University of Medea, Urban Pole, Medea, 26000, Algeria.
    Bailek, Nadjem
    Energies and Materials Research Laboratory, Faculty of Sciences and Technology, University of Tamanghasset, Tamanrasset, 10034, Algeria; Sustainable Development and Computer Science Laboratory, Faculty of Sciences and Technology, Ahmed Draia University of Adrar, Adrar, Algeria.
    Kuriqi, Alban
    CERIS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, 1049-001, Portugal; Civil Engineering Department, University for Business and Technology, Pristina, 10000, Kosovo.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hanini, Salah
    Laboratory of Biomaterials and Transport Phenomena (LBMPT), University of Medea, Urban Pole, Medea, 26000, Algeria.
    Colak, Ilhami
    Engineering and Architecture Faculty, Nisantasi University, Istanbul, Turkey.
    Abualigah, Laith
    Computer Science Department, Prince Hussein Bin Abdullah Faculty for Information Technology, Al al-Bayt University, Mafraq, 25113, Jordan; Hourani Center for Applied Scientific Research, Al-Ahliyya Amman University, Amman, 19328, Jordan; MEU Research Unit, Middle East University, Amman, 11831, Jordan; Applied Science Research Center, Applied Science Private University, Amman, 11931, Jordan; School of Computer Sciences, Universiti Sains Malaysia, Pulau Pinang, 11800, Malaysia; Department of Computing and Information Systems, School of Engineering and Technology, Sunway University Malaysia, Petaling Jaya, 27500, Malaysia.
    El-Kenawy, El-Sayed M.
    Faculty of Artificial Intelligence, Delta University for Science and Technology, Mansoura, 35712, Egypt.
    Assessing the Efficacy of Improved Learning in Hourly Global Irradiance Prediction2023Ingår i: Computers, Materials and Continua, ISSN 1546-2218, E-ISSN 1546-2226, Vol. 77, nr 2, s. 2579-2594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increasing global energy consumption has become an urgent problem as natural energy sources such as oil, gas, and uranium are rapidly running out. Research into renewable energy sources such as solar energy is being pursued to counter this. Solar energy is one of the most promising renewable energy sources, as it has the potential to meet the world’s energy needs indefinitely. This study aims to develop and evaluate artificial intelligence (AI) models for predicting hourly global irradiation. The hyperparameters were optimized using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton training algorithm and STATISTICA software. Data from two stations in Algeria with different climatic zones were used to develop the model. Various error measurements were used to determine the accuracy of the prediction models, including the correlation coefficient, the mean absolute error, and the root mean square error (RMSE). The optimal support vector machine (SVM) model showed exceptional efficiency during the training phase, with a high correlation coefficient (R = 0.99) and a low mean absolute error (MAE = 26.5741 Wh/m2), as well as an RMSE of 38.7045 Wh/m² across all phases. Overall, this study highlights the importance of accurate prediction models in the renewable energy, which can contribute to better energy management and planning.

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  • 28.
    Das, Himadri Tanaya
    et al.
    Centre of Excellence for Advance Materials and Applications, Utkal University, Bhubaneswar, Odisha, India.
    Balaji T, Elango
    Department of Chemistry, Utkal University, Bhubaneswar, Odisha, India.
    Dutta, Swapnamoy
    CEITEC-Central European Institute of Technology, Brno University of Technology, 612 00 Brno, Czech Republic.
    Das, Nigamananda
    Centre of Excellence for Advance Materials and Applications, Utkal University, Bhubaneswar, Odisha, India; Department of Chemistry, Utkal University, Bhubaneswar, Odisha, India.
    Das, Payaswini
    CSIR-Institute of Minerals and Materials Technology, Bhubaneswar, Odisha 751013, India.
    Mondal, Aniruddha
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Imran, Muhammad
    Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia.
    Recent trend of CeO2-based nanocomposites electrode in supercapacitor: A review on energy storage applications2022Ingår i: Journal of Energy Storage, ISSN 2352-152X, E-ISSN 2352-1538, Vol. 50, artikel-id 104643Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Emergence of supercapacitor's utilization is been clearly observed in recent years due to the advancement in energy conversion technologies as well as in energy storage systems. The supercapacitors are seemed to be attractive mainly due to its high-energy density, stable cycle life and longer lifetime. Additionally, sustainable nanotechnology played a crucial role in pushing the ongoing progress of supercapacitor technology. Among various popular materials, cerium oxide (CeO2) is one of the ceramic materials that have depicted positive electrochemical activity. CeO2 and its nanostructured composite materials are broadly investigated as a promising active material for supercapacitor applications. The enhancement in electrochemical performance due to addition of different elements to CeO2 was also been explained. The morphologies of prepared binary or ternary composite using CeO2 were also briefly discussed in this article.

  • 29.
    de Oliveira, Roger Alves
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Magnification of Transients at the Voltage Dips Starting and its Impacts on DFIG-based Wind Power Plants2022Ingår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 211, artikel-id 108244Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work shows that transients at voltage dips starting impact fault-ride-through of wind turbines. For fault-ride-through studies and manufacturer tests, it is therefore important to consider these transients and their magnification from the transmission grid through the collection grid to the wind turbines. Fault-ride-through studies in the literature do not consider the transient as a dip characteristic and employ overly-simplified models that do not consider the collection grid. This work studies in detail how the dip-starting transient changes during the propagation from the transmission grid to the wind-turbine terminals. It is also studied how this transient impacts the dynamic behaviour of the wind turbines in terms of the overvoltage on the DC-link of wind turbines based on doubly-fed induction generator (DFIG). The analyses are performed for several realistic configurations of a wind-power plant, all based on an existing installation. The results show that the magnitude of the transient is magnified when the resonant frequency of the collection grid is similar to the oscillation frequency of the transient. Moreover, the higher magnitude of the transient results in a significantly higher overvoltage on the DC-link. This work is the first in power quality literature to cover the collection and internal grid as a factor for the magnification of dip-staring transient. The main finding of this work is that the detailed models of the collection grid and the transients at the voltage dips starting must be not neglected when accessing the LVRT of wind turbines. It is strongly recommended to consider the details of the dip-starting transients and of the collection grid to assess the impact of dips on the wind turbines properly.

  • 30.
    De Souza Salles, Rafael
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah K.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Interharmonic Analysis for Static Frequency Converter Station Supplying a Swedish Catenary System2022Ingår i: 2022 20th International Conference on Harmonics & Quality of Power (ICHQP) Proceedings: “Power Quality in the Energy Transition”, IEEE, 2022Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper aims to present a waveform distortion analysis focused on interharmonics in measurements from a 70 kV busbar feeding a traction supply substation with four static frequency converters (SFC). The substation supplies a Swedish catenary system from 50 Hz public grid to 15 kV 16 ⅔ Hz. The paper assesses the interharmonics for different scenarios regarding the point of a connection configuration between the traction substation and the upstream grid, as well as a change in the number of SFCs connected in the substation. The IEC 61000-4-7 grouping method and spectrograms were used to illustrate the issue. The significant presence of interharmonics calls attention to the subject in railway application. The total indexes help to evaluate the broad picture of the phenomena. The work contributes to the waveform distortion and interharmonics in railway systems studies.

  • 31.
    Deng, Jifei
    et al.
    Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland.
    Eklund, Miro
    Department of Information Technology, Abo Akademi University, Turku, Finland; Semantum Ltd, Espoo, Finland.
    Sierla, Seppo
    cal Engineering and Automation, Aalto University, Espoo, Finland.
    Savolainen, Jouni
    Semantum Ltd, Espoo, Finland.
    Niemistö, Hannu
    Semantum Ltd, Espoo, Finland.
    Karhela, Tommi
    Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland; Semantum Ltd, Espoo, Finland.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland.
    Application of reinforcement learning for energy consumption optimization of district heating system2023Ingår i: 2023 IEEE 32nd International Symposium on Industrial Electronics (ISIE), IEEE, 2023Konferensbidrag (Refereegranskat)
  • 32.
    Dossow, Marcel
    et al.
    Technical University of Munich, Chair of Energy Systems, Boltzmannstr. 15 85748 Garching b. München Germany.
    Klüh, Daniel
    Technical University of Munich, Campus Straubing for Biotechnology and Sustainability, Professorship of Regenerative Energy Systems, Schulgasse 16 Straubing 93415 Germany.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. Technical University of Munich, Chair of Energy Systems, Boltzmannstr. 15 85748 Garching b. München Germany.
    Gaderer, Matthias
    Technical University of Munich, Campus Straubing for Biotechnology and Sustainability, Professorship of Regenerative Energy Systems, Schulgasse 16 Straubing 93415 Germany.
    Spliethoff, Hartmut
    Technical University of Munich, Chair of Energy Systems, Boltzmannstr. 15 85748 Garching b. München Germany.
    Fendt, Sebastian
    Technical University of Munich, Chair of Energy Systems, Boltzmannstr. 15 85748 Garching b. München Germany.
    Electrification of gasification-based biomass-to-X processes - a critical review and in-depth assessment2024Ingår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 17, nr 3, s. 925-973Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    To address the impacts of climate change, it is imperative to significantly decrease anthropogenic greenhouse gas emissions. Biomass-based chemicals and fuels will play a crucial role in substituting fossil-based feedstocks and reducing emissions. Gasification-based biomass conversion processes with catalytic synthesis producing chemicals and fuels (Biomass-to-X, BtX) are an innovative and well-proven process route. Since biomass is a scarce resource, its efficient utilization by maximizing product yield is key. In this review, the electrification of BtX processes is presented and discussed as a technological option to enhance chemical and fuel production from biomass. Electrified processes show many advantages compared to BtX and electricity-based processes (Power-to-X, PtX). Electrification options are classified into direct and indirect processes. While indirect electrification comprises mostly the addition of H2 from water electrolysis (Power-and-Biomass-to-X, PBtX), direct electrification refers to power integration into specific processing steps by converting electricity into the required form of energy such as heat, electrochemical energy or plasma used (eBtX). After the in-depth review of state-of-the-art technologies, all technologies are discussed in terms of process performance, maturity, feasibility, plant location, land requirement, and dynamic operation. H2 addition in PBtX processes has been widely investigated in the literature with process simulations showing significantly increased carbon efficiency and product yield. Similar studies on direct electrification (eBtX) are limited in the literature due to low technological maturity. Further research is required on both, equipment level technology development, as well as process and system level, to compare process options and evaluate performance, economics, environmental impact and future legislation.

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  • 33.
    Efkarpidis, Nikolaos
    et al.
    Institute of Electric Power Systems, University of Applied Sciences and Arts Northwestern Switzerland, Windisch, Switzerland.
    Geidl, Martin
    Institute of Electric Power Systems, University of Applied Sciences and Arts Northwestern Switzerland, Windisch, Switzerland.
    Yang, Chen-Wei
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Goranović, Andrija
    TU Wien, Institute of Computer Technology.
    Wilker, Stefan
    TU Wien, Institute of Computer Technology.
    Sauter, Thilo
    TU Wien, Institute of Computer Technology.
    Herbst, Ingo
    Department of Smart Infrastructure, Siemens Switzerland.
    A Robust KPI Framework for Smart Energy Systems of Different Scales2022Ingår i: 2022 IEEE 31st International Symposium on Industrial Electronics (ISIE), IEEE, 2022, s. 454-461Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nowadays, an increasing focus is placed on the development of smart energy systems (SESs) that combine a variety of heterogeneous sub-systems with largely varying applications. Due to their multidisciplinary nature, there are no universally accepted standards assessing their performance. Previous efforts typically define Key Performance Indicators (KPIs) only for specific SES types and application areas. This paper presents a robust KPI framework that can be applied to any SES type regardless of the application area. The proposed framework consists of four layers following the top-down approach. The layers define the application area, SES requirements, main stakeholders involved specifying their objectives and finally, the KPIs for each of the stakeholders' objectives. The proposed KPI framework is applied on the use cases of a European research project with different application areas showing its features.

  • 34.
    Efkarpidis, Nikolaos
    et al.
    Institute of Electric Power Systems, University of Applied Sciences and Arts Northwestern Switzerland, (FHNW), Klosterzelgstrasse 2, CH-5210 Windisch, Switzerland.
    Goranovic, Andrija
    Institute of Computer Technology, TU Wien, Gusshaus Str. 27-29/e384, AT-1040 Vienna, Austria.
    Yang, Chen-Wei
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Geidl, Martin
    Institute of Electric Power Systems, University of Applied Sciences and Arts Northwestern Switzerland, (FHNW), Klosterzelgstrasse 2, CH-5210 Windisch, Switzerland.
    Herbst, Ingo
    Siemens Schweiz AG Smart Infrastructure, Freilagerstrasse 40, CH-8047 Zurich, Switzerland.
    Wilker, Stefan
    Institute of Computer Technology, TU Wien, Gusshaus Str. 27-29/e384, AT-1040 Vienna, Austria.
    Sauter, Thilo
    Institute of Computer Technology, TU Wien, Gusshaus Str. 27-29/e384, AT-1040 Vienna, Austria.
    A Generic Framework for the Definition of Key Performance Indicators for Smart Energy Systems at Different Scales2022Ingår i: Energies, E-ISSN 1996-1073, Vol. 15, nr 4, artikel-id 1289Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growing integration of intermittent renewable energy sources (RESs) and the increasing trend of shutting down fossil-fuel-based power plants has brought about the need for additional flexibility in energy systems. This flexibility can be provided in various forms, including controllable generation and consumption, storage, conversions, and exchanges with interconnected systems. In this context, an increasing focus is placed on the development of smart energy systems (SESs) that combine different types of distributed energy resources (DERs), information and communication technologies (ICTs), demand side management (DSM), and energy conversion technologies. The utilization of SESs can lead to multiple benefits for the stakeholders involved; therefore, the assessment of their performance is a primary concern. Due to their multidisciplinary nature, there are no known or universally accepted standards for assessing the performance of SESs. Previous efforts only define key performance indicators (KPIs) for individual homogeneous subsystems, focusing on a specific SES type and application area. This paper focuses on the development of a novel comprehensive KPI framework that can be applied to any type of SES, regardless of the application area. The proposed framework consists of four layers that specify the application area, the main SES requirements, and the involved stakeholders’ objectives. Next, the KPIs are identified for each of the stakeholders’ objectives. The proposed KPI framework is applied to the use case of a European research project with different application areas, to demonstrate its features. Finally, a repository of KPIs is identified for each use case with respect to the aforementioned SES requirements.

  • 35.
    Efkarpidis, Nikolaos
    et al.
    Institute of Electric Power Systems, University of Applied Sciences and Arts Northwestern Switzerland (FHNW IEE), Windisch, Switzerland.
    Imoscopi, Stefano
    Dalle Molle Institute for Artificial Intelligence (IDSIA), Universita della Svizzera italiana (USI), Lugano, Switzerland.
    Bratukhin, Aleksey
    Center for Distributed Systems and Sensor Networks, Department for Integrated Sensor Systems, University for Continuing Education Krems, Wiener Neustadt, Austria.
    Brännvall, Rickard
    Research Institutes of Sweden (RISE), Luleå, Sweden.
    Franzl, Gerald
    Center for Distributed Systems and Sensor Networks, Department for Integrated Sensor Systems, University for Continuing Education Krems, Wiener Neustadt, Austria.
    Leopold, Thomas
    Energy&IT Group, Institute of Computer Technology, TU, Wien, Austria.
    Bauer, Valentin
    Energy&IT Group, Institute of Computer Technology, TU, Wien, Austria.
    Goranovic, Andrija
    Energy&IT Group, Institute of Computer Technology, TU, Wien, Austria.
    Wilker, Stefan
    Energy&IT Group, Institute of Computer Technology, TU, Wien, Austria.
    Yang, Chen-Wei
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Gustafsson, Jonas
    Research Institutes of Sweden (RISE), Luleå, Sweden.
    Geidl, Martin
    Institute of Electric Power Systems, University of Applied Sciences and Arts Northwestern Switzerland (FHNW IEE), Windisch, Switzerland.
    Sauter, Thilo
    Energy&IT Group, Institute of Computer Technology, TU, Wien, Austria; Center for Distributed Systems and Sensor Networks, Department for Integrated Sensor Systems, University for Continuing Education Krems, Wiener Neustadt, Austria.
    Proactive Scheduling of Mixed Energy Resources at Different Grid Levels2024Ingår i: IEEE Transactions on Sustainable Energy, ISSN 1949-3029, E-ISSN 1949-3037, Vol. 15, nr 2, s. 952-963Artikel i tidskrift (Refereegranskat)
  • 36.
    Etherden, Nicholas
    et al.
    Vattenfall R&D, Stockholm, Sweden.
    Aboukrat, Maxime
    Vattenfall R&D, Stockholm, Sweden.
    Cebollada, Virginia
    Vattenfall R&D, Stockholm, Sweden.
    Lingfors, David
    Uppsala University, Dep. Eng. Sciences, Uppsala, Sweden.
    Karlsson, Björn O.
    Dep. Building, Energy and Environmental Engineering, University of Gävle, Sweden.
    Shading losses for different types of residential PV systems and its city-wide impact on PV potential2019Ingår i: 9th Solar and Storage Integration Workshop: International Workshop on Integration of Solar Power and storage into Power Systems, Energianautics GmbH , 2019Konferensbidrag (Refereegranskat)
  • 37.
    Etherden, Nicholas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. Vattenfall R&D, 169 92 Stockholm, Sweden.
    Alhamwi, Mouaz
    Vattenfall R&D, 169 92 Stockholm, Sweden.
    Using Online Solar Photovoltaics Inverter Measurements to Determine the Hosting Capacity of Distribution Grids2023Ingår i: Solar RRL, E-ISSN 2367-198X, Vol. 7, nr 22, artikel-id 2300509Artikel i tidskrift (Refereegranskat)
  • 38.
    Etherden, Nicholas
    et al.
    Vattenfall R&D, Stockholm, Sweden.
    Nestorovic, Benjamin
    Vattenfall Eldistribution AB, Stockholm, Sweden.
    Isendahl, Christoffer
    E.ON Energidistribution AB, Malmö, Sweden.
    Ruwaida, Yvonne
    Vattenfall Eldistribution AB, Stockholm, Sweden.
    Unlocking the potential of flexibility2021Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, Institution of Engineering and Technology, 2021, artikel-id 0718Konferensbidrag (Refereegranskat)
    Abstract [en]

    The CoordiNet project within Horizon 2020 programme aims to demonstrate how Distribution System Operators (DSO) and Transmission System Operators (TSO) can act in a coordinated manner to procure and activate grid services in the most cost effective and reliable way. With 4 GWh of traded flexibility during winter of 2019/2020, the Swedish demo sites constitutes one of Europe's largest local flexibility markets for congestion management. The paper presents the experience from interviews with fifteen flexibility providers participating in the markets. Together they provide flexibility from a wide mix of different technologies including district heating, generation from waste disposal, aggregated consumer load, industrial heat pumps, gensets and residential housing blocks. Fifteen resource owners have made the journey to become flexibility providers. Understanding their experience and needs will help DSO develop products and business models for flexibility services as well as getting insight in the practical hurdles that hinder network customers to become a flexibility provider (FSP). The results from implementation of the platform, user interface, learnings on stakeholder interaction and initial evaluation of first two years operation of the market is also addressed.

  • 39.
    Etherden, Nicholas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. Vattenfall R&D, Stockholm, Sweden .
    Tavares de Oliveira, Tais
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    First Steps Towards a Standardised Hosting Capacity Method2021Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, Institution of Engineering and Technology, 2021, s. 931-934, artikel-id 0727Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the requirements for a standardised hosting capacity method. It outlines the needs and requirements for a standardised methodology as well as ongoing and upcoming standardisation activities in IEEE and IEC. The paper outlines the criteria for consensus, transparency, interoperability and stability required from a standardised hosting capacity method. The use of IEC 61968/61970 Common Grid Model Exchange Specification is proposed as a basis for reproducibility and benchmarking of results across network operators, countries, regions and network design methods.

  • 40.
    Fischer, Robert
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Investigation into sustainable energy systems in Nordic municipalities2020Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Kommunala energisystem i nordiska miljöer möter flera utmaningar: det kalla klimatet, storskaliga industrier, en stor andel elvärme och långa distanser driver energiförbrukningen. Medan åtgärder vidtas på efterfrågesidan för att minimera energianvändningen, kan utsläppsminskande åtgärder inom gruvdrift, industrier, uppvärmningen och transportsektorn öka förbrukningen av el och biobränslen. Fortsatt tillväxt av intermittent vind- och solkraft ökar elproduktion, men den planerade avvecklingen av svensk kärnkraft kommer att utmana tillförlitligheten i elsystemet i de nordiska länderna. Flaskhalsar i överförings- och distributionsnäten kan begränsa en potentiell tillväxt av elanvändningen i stadsområden, begränsa ny intermittent utbud, och påverka elutbyte mellan länderna. Miljöhänsyn kan begränsa ökad användning av biomassa. Lokala myndigheter är engagerade i att bidra till nationella klimatmål, samtidigt som de följer sina egna mål för ekonomisk utveckling, ökad självförsörjning av energi och överkomliga energikostnader.

    Mot bakgrund av dessa omständigheter undersöker denna avhandling befintliga tekniska och ekonomiska potentialer för förnybar energi i Norden med fokus på de nordliga länen i Finland, Norge och Sverige. Forskningen syftar vidare till att utveckla optimala lösningar för hållbara nordiska kommunala energisystem, där samspelet mellan stora energisektorer studeras, med tanke på att minimera årliga energisystemkostnader och samtidigt minska koldioxidutsläppen samt analysera påverkan på elimport till och export från kommunen.

    Denna forskning formulerar ett integrerad kommunalt energisystem som multimåloptimeringsproblem (multi-objective optimisation problem - MOOP), som löses genom att kombinera simuleringsverktyget EnergyPLAN med en evolutionär algoritm implementerad i Matlab. I ett första steg studeras kopplingen av el- och värmesektorerna, och i ett andra steg effekterna av en integrerad och alltmer förnybar transportsektor på energisystemet. Känslighetsanalys på viktiga ekonomiska parametrar och på olika utsläppsfaktorer utförs. Piteå (Norrbottens län, Sverige) är en typisk nordisk kommun som fungerar som en fallstudie för detta arbete.

    Forskningens slutsatser innebär att det finns betydande teknisk-ekonomiska potentialer för de undersökta förnybara resurserna. Optimeringsresultaten visar att koldioxidutsläppen från ett nordiskt kommunalt energisystem kan minskas med cirka 60% utan en avsevärd ökning av de totala energisystemkostnaderna och att den högsta elimporten kan minskas med upp till 38%. Resultat för år 2030 visar att transportsektorn kan ha en mycket hög elektrifieringsgrad och samtidigt används biobränslen i tunga fordon. Optimala lösningar är mycket känsliga för elpriser, räntor och utsläppsfaktorer.

    Detta arbete ger viktiga insikter om strategier för koldioxidminskning för integrerade energisektorer i ett perspektiv på nordiska kommuner. Min framtida forskning kommer att förfina transportmodellen, utveckla och tillämpa ett ramverk för beslutsanalys med flera kriterier (multi-criteria decision analysis - MCDA) som ska stödja lokala myndigheter att fastställa tekniskt och ekonomiskt hållbara lösningar i deras energiplanering.

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  • 41.
    Fischer, Robert
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Game theory-based analysis of policy instrument consequences on energy system actors in a Nordic municipality2024Ingår i: Heliyon, E-ISSN 2405-8440, Vol. 10, nr 4, artikel-id e25822Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The transition of energy systems requires policy frameworks and instruments to make both energy suppliers and consumers contribute to the common goal of emission reductions and to fairly allocate costs and benefits among market actors and the government. Assuming that market actors – suppliers and consumers adhering to their economic interests – would benefit from cooperating to mitigate emissions, this study applies a game theory-based approach to investigate the interaction between a local electricity supplier and a group of heating consumers not connected to district heating. Selected policy instruments are tested, and their consequences are analyzed in the context of a representative Nordic municipality. The results show that the auction-based Contract for Difference policy instrument is the most suitable one in the studied Nordic context to achieve significant levels of CO2 emissions reduction. It creates a higher level of strategic interaction between the actors, that would be lacking otherwise, under the form of transfer payments from consumers to supplier, and avoids costs to the general taxpayer. While this is sufficient to promote the investments in renewables by the supplier, additional subsidy policies are required to enable the heating consumers to invest in more capital-intensive energy efficiency measures or biomass heating.

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  • 42.
    Forsberg, Jonas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Energy transition in transportation: Applying TIMES-based energy system optimisation models to sub-national levels2021Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Transportation is embedded in the fabric of society and a key enabler of socio-economic development, but it is also a major source of carbon dioxide (CO2) and local air pollution (AP). Cities collectively account for around three quarters of total energy-related CO2 emissions, and the negative health impacts from local APs are most felt in dense urban environments. Thus, transitioning away from current fossil fuel regime in urban transportation is necessary to address both global and local challenges. Mathematical models as energy system optimisation models (ESOMs) are commonly applied to explore contrasting energy futures and to provide insights on how the energy system (or specific sub-sectors) may evolve under different conditions. However, ‘typical’ national level models are not fully adapted to capture the characteristics of local (city) transportation, and previous city-level ESOM based analyses have focused on decarbonisation of local energy systems, thus omitting other local policy considerations as e.g. air quality, and several studies excluded transportation altogether. 

    In this thesis, a generic city-level ESOM framework (TIMES-City) was further adapted and used to provide policy-relevant insights on the anticipated energy transition of the local transport sector. The underlying work rests on a systems analysis approach, building on careful consideration of the overall system performance and boundaries, understanding of specific system characteristics, and challenges and opportunities facing local ‘system managers’; this has implications for model representation and for quantitative and qualitative modelling assumptions. Further, availability and quality of local transport, energy and emission data needed to calibrate models poses significant challenges, and considerable effort was also put on producing projections for future transport demand (a key model input), using lessons and input data from traditional transport demand models. These considerations were addressed in Paper I. 

    The model was then applied to two different cases (in Sweden) to explore potential conflicts and co-benefits between ambitious climate targets and deep cuts in APs (Paper II), and to assess the roles of local and regional governments in CO2 mitigation when also considering ambitious national-scale policies (Paper III). The results of Paper II indicate that substituting fossil fuels for biofuels in conventional vehicles is the least-cost decarbonisation pathway, however this produces only minor or even negative benefits to air quality. While, zero-emission vehicles cut all local tail-pipe emissions, but their total impact on climate change mitigation is determined by upstream impacts from the conversion and distribution of energy carriers. Thus, ensuring low levels of total CO2 and APs from transportation calls for re-coupling of the local and global responsibilities and motivations into comprehensive mitigation strategies. The results of Paper III indicate that current Swedish national mitigation measures will drive down CO2 emissions in transportation considerably, but biofuel availability and BEV (battery electric vehicles) costs are critical for the rate and extent of the transition, while locally and regionally determined measures to enable shifts (from car) to active travelling, public transportation and home-based work have a much more limited direct impact. Nonetheless, these measures, along with city investments in BEVs and charging infrastructure which pave the way also for residents and local businesses, can help to reduce overall energy intensity of the transport sector, thus slowing down growth in fuel demand and contribute to reaching ambitious climate targets with limited renewable resources (as e.g. biofuels). The two studies (Papers II and III) illustrate the usefulness of applying comprehensive ESOMs also at sub-national levels, providing insights on both global and local sustainability implications as well as deeper understanding of the roles of local and regional decision-makers in enabling and supporting low-carbon transitions in transportation. 

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  • 43.
    Forsberg, Jonas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    On the road to climate neutral Swedish transportation: Energy system modelling to support the transition at national, regional, and local levels2023Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Transportation is a critical pillar of modern society. Over the past decades, growth in mobility of people and goods have been both enabled by and dependent upon fossil fuels. Strong action is needed to break this dependence in order to reduce CO2. The overall aim of this thesis is to support the transition towards climate neutral transportation in Sweden considering local, regional, and national settings, by use of TIMES-based ESOMs. This is addressed by i) developing and adapting transport sector representation in TIMES models considering context specific conditions and preferences, ii) applying the models to define and explore alternative long-term scenarios that meet the overall goals, iii) and identify key measures and policy implications for achieving climate neutral transportation.

    In Paper I (Local setting) key considerations and requirements in respect of modelling local energy transition of transportation in a TIMES energy system modelling framework was outlined. The model was then applied to address potential trade-offs between global climate concerns and local air quality issues (Paper II – Local setting). The results showed that decarbonisation with biofuels does little to enhance local air quality, while zero-emission vehicles – that eliminate all local tailpipe emissions – can induce significant upstream CO2 emissions (from energy supply sectors). Comprehensive multi-level strategies are needed to drastically reduce both CO2 and local air pollutants. In Paper III (Regional setting), a participatory modelling approach was applied that involved local practitioners from 15 municipalities. The model results showed that strong national policies can drive down CO2 emissions drastically, and that the impacts from sub-national strategies was very limited under these policies. Still, during the discussions with local practitioners it was emphasized that local action is needed for enabling the measures seen as cost-efficient in the model analysis.

    The TIMES-Sweden model was adapted and used to explore key decarbonisation options in passenger and freight transportation, in a whole-energy-systems perspective. The model was disaggregated to capture underlying contextual heterogeneity in passenger transportation found across the country (Paper IV – National setting). The results showed that different policy strategies have different implications depending on the context, thus, underpinning a shift from one-size-fits-all policies into more regionally tailored strategies. Next (Paper V – National setting), the same model was used to investigate principally different modes of decarbonising domestic freight transportation. The results showed that road freight electrification reduces total demand for electricity over the entire energy system compared to the biofuel and the e-fuel pathways respectively, while also freeing biomass for other purposes than producing biofuels for road vehicles.

    Finally, the usefulness of ESOMs to identify policies to accelerate the decarbonization of transportation has been demonstrated, while outlining some challenges. For local level, the necessary data to calibrate the model was often not available, or available but with a system boundary representation incompliant with the model approach (e.g., fuel statistics). At the national level, a new approach was introduced that capture the underlying contextual factors of different actors. While capturing differences between urban, suburban and rural conditions, more research is needed to identify policies that ensure a just transition across socioeconomic groups.

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  • 44.
    Forsberg, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Krook-Riekkola, Anna
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Klimatåtgärder inom transportsektorn sett i ett energisystemperspektiv – Utsläppsutrymme och åtgärdskostnader2024Rapport (Övrigt vetenskapligt)
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    fulltext
  • 45.
    Forsberg, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Krook-Riekkola, Anna
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Recoupling Climate Change and Air Quality: Exploring Low-Emission Options in Urban Transportation Using the TIMES-City Model2021Ingår i: Energies, E-ISSN 1996-1073, Vol. 14, nr 11, artikel-id 3220Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fossil fuels in transportation are a significant source of local emissions in and around cities; thus, decarbonising transportation can reduce both greenhouse gases (GHGs) and air pollutants (APs). However, the degree of these reductions depends on what replaces fossil fuels. Today, GHG and AP mitigation strategies are typically ‘decoupled’ as they have different motivations and responsibilities. This study investigates the ancillary benefits on (a) APs if the transport sector is decarbonised, and (b) GHGs if APs are drastically cut and (c) the possible co-benefits from targeting APs and GHGs in parallel, using an energy-system optimisation model with a detailed and consistent representation of technology and fuel choices. While biofuels are the most cost-efficient option for meeting ambitious climate-change-mitigation targets, they have a very limited effect on reducing APs. Single-handed deep cuts in APs require a shift to zero-emission battery electric and hydrogen fuel cell vehicles (BEVs, HFCVs), which can result in significant upstream GHG emissions from electricity and hydrogen production. BEVs powered by ‘green’ electricity are identified as the most cost-efficient option for substantially cutting both GHGs and APs. A firm understanding of these empirical relationships is needed to support comprehensive mitigation strategies that tackle the range of sustainability challenges facing cities.

  • 46.
    Fotouhi, Abbas
    et al.
    Advanced Vehicle Engineering Centre, School of Aerospace, Transport and Manufacturing (SATM), Cranfield University, Bedfordshire, UK.
    Shateri, Neda
    School of Mechanical, Aerospace and Automotive Engineering, Coventry University, Coventry, UK.
    Laila, Dina Shona
    School of Mechanical, Aerospace and Automotive Engineering, Coventry University, Coventry, UK.
    Auger, Daniel J.
    Advanced Vehicle Engineering Centre, School of Aerospace, Transport and Manufacturing (SATM), Cranfield University, Bedfordshire, UK.
    Electric vehicle energy consumption estimation for a fleet management system2021Ingår i: International Journal of Sustainable Transportation, ISSN 1556-8318, E-ISSN 1556-8334, Vol. 15, nr 1, s. 40-54Artikel i tidskrift (Refereegranskat)
  • 47.
    Furusjö, Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. IVL Swedish Environmental Research Institute, Climate & Sustainable Cities.
    Ma, Chunyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Carvalho, Lara
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Alkali enhanced biomass gasification with in situ S capture and novel syngas cleaning: Part 1: Gasifier performance2018Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 157, s. 96-105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Previous research shows that alkali addition in entrained flow biomass gasification can increase char conversion and decrease tar and soot formation through catalysis. This paper investigates two other potential benefits of alkali addition: increased slag flowability and in situ sulfur capture.

    Thermodynamic equilibrium calculations show that addition of 2–8% alkali catalyst to biomass completely changes the chemical domain of the gasifier slag phase to an alkali carbonate melt with low viscosity. This can increase feedstock flexibility and improve the operability of an entrained flow biomass gasification process. The alkali carbonate melt also leads to up to 90% sulfur capture through the formation of alkali sulfides. The resulting reduced syngas sulfur content can potentially simplify gas cleaning required for catalytic biofuel production.

    Alkali catalyst recovery and recycling is a precondition for the economic feasibility of the proposed process and is effected through a wet quench. It is shown that the addition of Zn for sulfur precipitation in the alkali recovery loop enables the separation of S, Ca and Mg from the recycle. For high Si and Cl biomass feedstocks, an alternative separation technology for these elements may be required to avoid build-up.

  • 48.
    Galkin, Nikolai
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Yang, Chen-Wei
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Berezovskaya, Yulia
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Vesterlund, Mattias
    ICE Data Center, RISE Research Institutes of Sweden AB, 97347 Luleå, Sweden.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Department of Electrical Engineering and Automation, Aalto University, 02150 Espoo, Finland.
    On Modelling of Edge Datacentre Microgrid for Participation in Smart Energy Infrastructures2022Ingår i: IEEE Open Journal of the Industrial Electronics Society, E-ISSN 2644-1284, Vol. 3, s. 50-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Datacentres are becoming a sizable part of the energy system and are one of the biggest consumers of the energy grid. The so-called “Green Datacentre” is capable of not only consuming but also producing power, thus becoming an important kind of prosumers in the electric grid. Green datacentres consist of a microgrid with a backup uninterrupted power supply and renewable generation, e.g., using photovoltaic panels. As such, datacentres could realistically be important participants in demand/response applications. However, this requires reconsidering their currently rigid control and automation systems and the use of simulation models for online estimation of the control actions impact. This paper presents such a microgrid simulation model modelled after a real edge datacentre. A case study consumption scenario is presented for the purpose of validating the developed microgrid model against data traces collected from the green edge datacentre. Both simulation and real-time validation tests are performed to validate the accuracy of the datacentre model. Then the model is connected to the automation environment to be used for the online impact estimation and virtual commissioning purposes.

  • 49.
    Gao, Kai
    et al.
    Institute of Future Cities, The Chinese University of Hong Kong, Hong Kong, China.
    Fong, K. F.
    Division of Building Science and Technology, College of Engineering, City University of Hong Kong, Hong Kong, China.
    Lee, C. K.
    Division of Building Science and Technology, College of Engineering, City University of Hong Kong, Hong Kong, China.
    Lau, Kevin Ka-Lun
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Ng, Edward
    Institute of Future Cities, The Chinese University of Hong Kong, Hong Kong, China.
    Balancing thermal comfort and energy efficiency in high-rise public housing in Hong Kong: Insights and recommendations2024Ingår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 437, artikel-id 140741Artikel i tidskrift (Refereegranskat)
  • 50.
    Garmabaki, Amir Soleimani
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Thaduri, Adithya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Famurewa, Stephen Mayowa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Adapting Railway Maintenance to Climate Change2021Ingår i: Sustainability, E-ISSN 2071-1050, Vol. 13, nr 24, artikel-id 13856Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Railway infrastructure is vulnerable to extreme weather events such as elevated temperature, flooding, storms, intense winds, sea level rise, poor visibility, etc. These events have extreme consequences for the dependability of railway infrastructure and the acceptable level of services by infrastructure managers and other stakeholders. It is quite complex and difficult to quantify the consequences of climate change on railway infrastructure because of the inherent nature of the railway itself. Hence, the main aim of this work is to qualitatively identify and assess the impact of climate change on railway infrastructure with associated risks and consequences. A qualitative research methodology is employed in the study using a questionnaire as a tool for information gathering from experts from several municipalities in Sweden, Swedish transport infrastructure managers, maintenance organizations, and train operators. The outcome of this questionnaire revealed that there was a lower level of awareness about the impact of climate change on the various facets of railway infrastructure. Furthermore, the work identifies the challenges and barriers for climate adaptation of railway infrastructure and suggests recommended actions to improve the resilience towards climate change. It also provides recommendations, including adaptation options to ensure an effective and efficient railway transport service.

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