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  • 1. Aalhuizen, Christoffer
    Potential of V2G in a Rural Low-Voltage Grid on Gotland for Voltage and Power Capacity Control2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Swedish transportation sector needs to undergo major changes in order to achieve the established goals for climate and environment. The largest change is the replacement of fossil-fuelled vehicles to vehicles propelled by renewable energy sources, such as biofuels and electricity. To account for an increase in local electric power consumption, the electric power infrastructure of Sweden needs to adapt through expansion and reconstruction of the electric power grid. However, changes in infrastructure are usually expensive. It is therefore suitable to also examine alternative solutions, which could potentially be more cost efficient. One of these solutions are vehicle-to-grid (V2G), where electric vehicles acts as local electric power control and provides auxiliary services to the electric power grid. This thesis is a case study of a part of a low-voltage electric power grid on Gotland, with the goal of analysing the potential of V2G in the investigated area. The study focused on utilizing V2G for balancing electric power consumption and generation, and for adjusting voltage levels. Simulations of the area were executed in PSS®E for three different cases; one high-load case, low-load case and average-load case. It was found that by utilizing V2G a ramp up of electric power during mornings was delayed by approximately one hour, making the electric power grid potentially more compatible with photovoltaics (PV). However, the overall effects from V2G was fairly low. This outcome can partly be explained by the assumptions made in the report, and also due to some odd behaviour of the system model. 

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  • 2.
    Aarthi, Aishwarya Devendran
    et al.
    LKAB, Sweden.
    Mainali, Brijesh
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Linnaeus University.
    Khatiwada, Dilip
    KTH Royal Institute of Technology, Sweden.
    Golzar, Farzin
    KTH Royal Institute of Technology, Sweden.
    Mahapatra, Krushna
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Implementation of GIS-AHP Framework for the Identification of Potential Landfill Sites in Bengaluru Metropolitan Region, India2023In: The 9th International Conference on Energy and Environment Research. ICEER 2022. / [ed] Caetano, N.S., Felgueiras, M.C., Springer, 2023Conference paper (Refereed)
    Abstract [en]

    Uncontrolled open dumping and burning of municipal solid waste (MSW) has resulted in soil, water, and air pollution in many urban cities in India. Landfills are the most common cost-effective solution for MSW management in many developing countries like India. However, the identification of suitable landfill sites always remains a challenging task as it involves the selection of several environmental criteria set by the local authorities. The objective of this study is to identify the most potential landfill sites proposed by the Government in Bengaluru Metropolitan Region, Karnataka state, India using Geographic Information System enabled Analytical Hierarchy Process based multi-criteria evaluation technique. Several criteria and constraints as recommended by the local authorities along with the proximity to the solid waste processing plants are used to identify the potential landfill sites in the study region. The study identified three highly suitable sites (Neraluru, Gudhatti, Madivala) for landfills which are not only environmentally sustainable but also economically attractive as they are closer to the solid waste processing plants minimizing the transportation cost involved in the disposal of solid waste from the source to the final disposal sites in the study region.

  • 3.
    Abadie, Brendan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Power investment outlook for Chile to 20402020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aims to build a medium-term (2019-2040) model for the Chilean electricity generation system in the OSeMOSYS software, a linear cost optimisation model, in light of the most recent developments in government policy and targets. In 2019, the Chilean government committed to decommissioning all coal plants by 2040 at the latest, and set out a non-binding target to be carbon neutral by 2050. The carbon neutrality target could be enshrined in the climate change law, which has yet to be ratified. In this thesis, a focus was put on the upfront capital cost of the system, and the emissions attributable to Chile’s GHG Inventory (called the SNI GHG in Chile) from operating the system. Three scenarios are developed within the thesis, in line with three paths the power system may follow: a BAU scenario including current power purchase agreements, a scenario in which power purchase agreements for fossil fuels are bought out and the free market then takes over, and a non-conventional renewable energy (NCRE) scenario in which certain renewable technologies account for 68% of production in 2040. The model is validated against the results from 2019 and a broadly similar model developed in the private sector. Sensitivity analysis scenarios were conducted for the input parameters: price of natural gas, price of coal, capital cost of solar PV, capital cost of wind, capital cost of wind & solar, and the capacity factor of hydropower. The sensitivity analyses show the most sensitive input parameters are the price of natural gas and capital cost of wind with respect to the outputs of capital cost, NCRE production ratio such as the share of all solar, wind, and certain hydro technologies as a percentage of total electricity production and GHG emissions.

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  • 4.
    Abbott, Michele
    et al.
    RAND Corp, Pardee RAND Grad Sch, Santa Monica, CA 90406 USA..
    Bazilian, Morgan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Columbia Univ, Swedish Royal Inst Technol, Ctr Global Energy Policy, New York, NY 10027 USA..
    Egel, Daniel
    RAND Corp, Santa Monica, CA 90406 USA..
    Willis, Henry H.
    RAND Corp, Santa Monica, CA 90406 USA..
    Examining the food-energy-water and conflict nexus2017In: Current Opinion in Chemical Engineering, E-ISSN 2211-3398, Vol. 18, p. 55-60Article, review/survey (Refereed)
    Abstract [en]

    There is growing evidence of a strong linkage or 'nexus' between conflict - both domestic and international - and food, energy, and water (FEW) resources and services. This article demonstrates a positive, significant correlation between two measures, FEW security and political stability, and reviews the evidence for how each of these three types of resource insecurities affects political and social stability. We describe what is known about the FEW-conflict nexus itself, note that remaining knowledge gaps include evidence on developing governance structures and preparing for climate change, and examine the types of policies that countries and international donors might take to help mitigate the role that FEW can play in affecting stability.

  • 5.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    State of the art in hydrogen liquefaction2020In: Proceedings of the ISES Solar World Congress 2019 and IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2019, International Solar Energy Society , 2020, p. 1311-1320Conference paper (Refereed)
    Abstract [en]

    Hydrogen is a potential option to replace fossil fuels considering the increasing demand of energy applications. It is naturally abundant and is regarded as a suitable energy carrier. There has been extensive research to improve the efficiency of storing hydrogen with different methods, including gas compression, liquefaction and sorption in metal hydrides or carbon nanotubes. A comparison of the storage methods shows that liquefaction of hydrogen is more beneficial than compression of hydrogen in terms of higher volumetric capacity, and it is more technologically mature than sorption technologies. This makes it more plausible for long distance distribution. On the other hand, the obstacles in full exploitation of the method are low energy efficiency of the liquefaction process and associated high cost. The recent research has been focusing on increasing the energy efficiency of the storage process. This paper provides, with regard to the conventional methods, a state of the art review of the novel and modified liquefaction process and the latest developments in increasing the efficiency of the energy intensive process. Furthermore, the developments in combining the hydrogen liquefaction plants with renewable energy sources are covered and reviewed. Finally, the ongoing development of hydrogen liquefaction is highlighted.

  • 6.
    Abdollahi, Elnaz
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Hamon, Camille
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Potential profits from ancillary service markets2023Report (Other academic)
    Abstract [en]

    In this deliverable from the SeCoHeat project, profits that can be made with 1 MWh of electricity production capacity on existing ancillary service markets are evaluated in 2020 and 2021. Profits are evaluated for four different marginal production costs corresponding to the following fuels for a CHP power plant: waste (assumed fuel price: 0 kr/MWh), recycled wood (10 kr/MWh), wood chips (20 kr/MWh) and wood pellets (30 kr/MWh). The results show that except for wood chips and wood pellets in 2020, the most profitable ancillary service markets are FFR (fast-frequency response) and aFRR down (automatic frequency restoration reserves for down-regulation). The reasons are that (1) producers don’t have to withhold capacity from the day-ahead market when their participate in these two markets and (2) producers get compensated for the capacity reserved for the ancillary service markets. For wood chips, the FFR market was the most profitable in 2020, followed by the mFRR down market (manual frequency restoration reserves for down-regulation). The reason for the mFRR down market to be more profitable than the aFRR down market for this fuel is that the profits from mFRR down depend on the avoided fuel costs, which are higher for wood chips than for waste and recycled wood. In 2021, all prices started increasing significantly, which decreased the relative profitability of the mFRR down compared to other markets. For wood pellets, the mFRR down market was also the second most profitable market in 2020, for the same reasons. The most profitable one in 2020 was the mFRR up market (manual frequency restoration reserves for up-regulation). The reason is that the higher fuel price of these two fuels entails low participation in the day-ahead market. Therefore, withholding capacity from the day-ahead market to be able to participate on the mFRR up market brings additional profits. In 2021, however, day-ahead prices started increasing significantly (a trend that continued into 2022) and the mFRR up market became the least profitable market for these two fuels. The profit evaluation performed in this deliverable is purely economic. It does not include the sector coupling to the heat sector (which entails limitation of the available electricity production capacity but also a possibility to store heat if storage is available) nor does it include other technical limitations such as ramp rates. These aspects will be considered in follow-up work in this project. This report has been compiled within the scope of the project SeCoHeat - Sector coupling of district heating with the electricity system: profitability and operation. The project is financed by the Research and Development Foundation of Göteborg Energi.

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  • 7.
    Abellán Guallarte, Alejandro
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Energy analysis between traditional hot water circulation system and an innovative pipe-in-pipe system2022Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We are at a time when energy efficiency and the reduction in the use of non-renewable energy is an important objective in all aspects and will continue to be so, therefore it is necessary to try to reduce energy and heat losses in the systems used in homes and, in particular, in the domestic hot water (DHW) system. This study aims to find out the advantages and disadvantages of an innovative pipe-in-pipe (PIP) system for DHW circulation with respect to the conventional system of two separate pipes. Previous studies have shown that DHW circulation is indeed an important point of energy losses in the home and that it is possible to reduce these losses by using the innovative system under study. The properties and coefficients defining the heat transfer system have been obtained for both the traditional and innovative systems by using empirical equations and iterative processes, indicating a 32% reduction in heat losses in favour of the pipe-in-pipe system. However, this result has been obtained in a kind of case study, using some simplifying assumptions, needed to accomplish to work within limited time. So the result could vary if a somewhat different system is studied, which is why it is necessary to carry out further studies and research on this subject in order optimize DHW systems in buildings.

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  • 8.
    Abeywardana, Asela Janaka
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Solar - Biomass hybrid system for process heat supply in medium scale hotels in Sri Lanka2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel.

    Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels. 

    When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area.  

    This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.    

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  • 9.
    Abghari, Shahrooz
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science.
    Boeva, Veselka
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science.
    Brage, Jens
    NODA Intelligent Systems AB, SWE.
    Grahn, Håkan
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science.
    A Higher Order Mining Approach for the Analysis of Real-World Datasets2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 21, article id 5781Article in journal (Refereed)
    Abstract [en]

    In this study, we propose a higher order mining approach that can be used for the analysis of real-world datasets. The approach can be used to monitor and identify the deviating operational behaviour of the studied phenomenon in the absence of prior knowledge about the data. The proposed approach consists of several different data analysis techniques, such as sequential pattern mining, clustering analysis, consensus clustering and the minimum spanning tree (MST). Initially, a clustering analysis is performed on the extracted patterns to model the behavioural modes of the studied phenomenon for a given time interval. The generated clustering models, which correspond to every two consecutive time intervals, can further be assessed to determine changes in the monitored behaviour. In cases in which significant differences are observed, further analysis is performed by integrating the generated models into a consensus clustering and applying an MST to identify deviating behaviours. The validity and potential of the proposed approach is demonstrated on a real-world dataset originating from a network of district heating (DH) substations. The obtained results show that our approach is capable of detecting deviating and sub-optimal behaviours of DH substations.

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  • 10.
    Abid, Hamza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Techno-economic analysis of energy storage integration for solar PV in Burkina Faso2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electrification in rural areas of West African countries remain to be a challenge for the growth of the region. The Economic Community of West African States (ECOWAS) has set a target of 2030 to achieve 100% electrification in all member countries. Burkina Faso is one of the least electrified countries in the world, where only 9 % of the rural population has access to electricity. This study presents a conceptualization of techno-economic feasibility of pumped hydro storage (PHS) and electric batteries with solar photovoltaics (PV) in the context of Burkina Faso. The results are explored for an off grid standalone PV plus storage system for a rural setting and a grid connected PV system for an urban setup. The least cost configurations for both the cases are determined using HOMER (Hybrid Optimization Model for Electric Renewables). The results indicate the need of extended solar penetration in Burkina Faso in response to the challenges of low electrification rates in the country. Adding more PV to the present electricity mix of Burkina Faso could drive down the cost of energy by 50 % compared to the present grid electricity prices by making cheap electricity available to the local population. Adding PHS to grid connected PV leads to a cost reduction of 8% over a lifetime of 25 years which does not provide enough motivation for the high investments in storage at present. Policy interventions that allow stacking up of revenues and benefits of storage are needed to make it more competitive. PV plus pumped hydro storage remains the optimal system architecture as compared to PV plus electric batteries for off grid standalone systems provided the geographic availability of lower and upper reservoirs. The capital cost of PV remains to be the most dominating factor in the cost of optimal system for both the urban and the rural cases, and driving down the costs of PV would have the most positive effect for increased electricity access in the country.

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  • 11.
    Abid, Hamza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Thakur, Jagruti
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Khatiwada, Dilip
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bauner, David
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability, Industrial Dynamics & Entrepreneurship. Renetech AB, Sweden.
    Energy storage integration with solar PV for increased electricity access: A case study of Burkina Faso2021In: Energy, E-ISSN 0360-5442, Vol. 230, no 120656, p. 120656-Article in journal (Refereed)
    Abstract [en]

    Electricity access remains a challenge for the majority of the West African countries, wherein 5 out of 16 have an electrification rate of less than 25%, with Burkina Faso having only 9% of the rural population with electricity access in 2017. This study presents a techno-economic feasibility analysis of solar PV system integration with conceptualized Pumped Hydro Storage (PHS) and electric batteries for Burkina Faso. The study explores two cases (a) an off-grid PV with a storage system for rural areas and (b) a grid-connected PV system for an urban location. The least-cost configuration of PV with feasible storage is investigated using HOMER. The results show that Solar PV with PHS remains the optimal system configuration for both rural and urban cases even when the construction costs of lower and upper reservoirs are considered. Battery energy storage systems remain an economically expensive solution even when the added costs of pumped hydro storage are included, owing to the low lifetime and high capital costs of battery storage. The capital cost of PV remains to be the most dominating factor for both cases, signifying the importance of policy interventions for cost reduction of PV for increased green electrification in West African countries.

  • 12.
    Abolghasemi Moghaddam, Saman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    The effects of low-emissivity window films on thermal comfort and energy performance of a historic stone building in cold climate: computer simulations with "IDA ICE"2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Low-emissivity (low-E) window films are designed to improve the energy performance of windows and prevent indoor overheating by solar radiation. These films can be applied to different types of glazing units without the need for changing the whole window. This characteristic offers the possibility to improve the energy performance of the window of old and historic buildings for which preservation regulations say windows should remain more or less unchanged. This research aims to figure out to what extent a low-E window film can improve thermal comfort and energy performance of an old three-storey historic stone building in the cold climate of Mid-Sweden. In this research, first, with help of the simulation software “IDA ICE”, the entire building was modelled without window films in a one-year simulation. Second step was to add the low-E window films (3M Thinsulate Climate Control 75 (CC75)) to all the windows and repeat the simulation. Comparison between the results of the two cases revealed an improvement in energy use reduction as well as the thermal comfort when applying the films. For the application of the window films, a cost analysis using payback method was carried out which showed a long- time payback period. Although an investment with a long-time payback period is considered as a disadvantage, for historic buildings with very strict retrofit regulations specially when it comes to the building’s facades, application of the low-emissivity window films for better energy performance and thermal comfort is among the recommendable measures, but not necessarily the best.

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  • 13.
    Abolhosseini, Shahrouz
    et al.
    Petr Univ Technol, Natl Iranian Oil Co, Int Affairs, Tehran, Iran.
    Heshmati, Almas
    Jönköping University, Jönköping International Business School, JIBS, Economics. Sogang Univ, Seoul, South Korea.
    Rashidghalam, Masoomeh
    Univ Tabriz, Tabriz, Iran.
    Energy security and competition over energy resources in Iran and Caucasus region2017In: AIMS Energy, ISSN 2333-8326, E-ISSN 2333-8334, Vol. 5, no 2, p. 224-238Article in journal (Refereed)
    Abstract [en]

    Energy security as a dominant factor in international stability is of great importance for major economies. The global energy market with its current level of supply and demand relies on energy sources in the Middle East, Caucasus, Central Asia and Russia. After the Fukushima disaster nuclear powers in Europe view renewable energy sources as a serious alternative. Europe’s energy vulnerability has deteriorated due to the Russia-Ukraine conflict. However, renewable energy sources are not large enough to replace nuclear power completely. This trend will continue with climbing demand especially in the natural gas sector as clean energy. In this research, Caucasus and Iran are considered the main sources and routes for energy transmission to the global market, including Europe. Caucasus plays a key role in bridging Europe and Asia. Also, Iran is an alternative for energy transmission to Europe after lifted sanctions. As part of the European active supply diversification policy Iran has capacity to reduce Europe’s energy dependency on Russia. However, changes in US new administration America First Policy is harmful for the EUs energy security. Caucasus aims to catch a large share of the European energy market since the Baku-Tbilisi-Ceyhan pipeline has started operations and Iran is also trying to expand its market to become a sustainable source of energy for major consumers. Therefore, Iran and Caucasus are considered reliable energy suppliers for Europe. In this regard, we analyze the best motivation for changing the direction new suppliers’ energy policies towards Europe and suggest alternative solutions to compete with rival countries in order to enhance energy security.

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  • 14.
    Abrahamsson, Curt Johan David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Pérez-Loya, Jesús José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Fregelius, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Evestedt, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bladh, Johan
    Lundin, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Magnetic thrust bearing for a 10 MW hydropower generator with a Kaplan turbine2018Conference paper (Refereed)
  • 15.
    Abrahamsson, Linnéa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energianvändning vid pelletering: En undersökning av strömningsenergins betydelse för den totala energianvändningen vid pelletering2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Biofuels make up 25% of Sweden’s energy supply and the majority of biofuels used are made from wood. Wood pellets is one type of biofuel and in Sweden, 1.6 million tonnes of wood pellets were produced in 2018. Different pellet properties such as durability and energy use for production is often tested in a single pellet press. The total energy use for making a pellet in an industrial scale machine is the sum of the energy required for three different component sequences, compression, friction and flow. Flow is when the material that lies on the surfaces between the press channel openings is compressed and pushed downwards towards the coned openings and the materiel in the coned opening is deformed and pushed down to the press channel.

    Only compression and friction can be studied using a conventional single pellet press. Thus, this study focuses on the impact of the flow component on the total energy use for pelletizing. In order to do this, energy used for compression, friction and flow, as well as the power required for the material to enter the flow component, Fflow, has been studied for three different particle sizes.

    Fresh spruce with a moisture content of 10% has been pressed in different dies. With these pressings, the impact of the flow component, as well as the impact of pressing material located around the coned press channel opening on the total energy use was determined.

    Particle size did not affect energy use. Fflow was higher for pressings with material located on the surface around the coned opening, compared to pressings without. This resulted in an increased compression energy for pressings with material around the coned opening. The material located around the press channel opening affected the pelletizing so that the produced pellet was 1 mm shorter, which resulted in a lower energy use for the friction component. Energy used by the flow component made up over 43-57% of the total energy use. The part of the flow energy that is needed to compress the material around the press channel opening and move that material towards the opening stood for 35-52% of the total energy use for palletization.

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  • 16.
    Abran, Eszter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Andersson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Intäktsanalys av vindkraft som reglerresurs: Med och utan batterilager2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to ensure a stable power system, a balance between production and consumption at every given moment is necessary. An indication of this balance is the system frequency, which deviates from its nominal value in case of imbalance. With an increasing share of weather dependent energy in the Nordic synchronous system, such as wind power, the need for stabilizing services are becoming even more crucial. Ancillary services are a way of keeping the frequency stabilized, they are provided by different actors in the power system with flexible production or consumption. This contributes to increasing or decreasing the input and output of energy to the system when needed. Ancillary services are procured in separate markets that are structured and designed by the transmission system operator, Svenska kraftnät.

    This thesis investigates wind power and its potential of providing ancillary services in the Swedish power system. The report presents two different studies which are performed based on two specific wind farms in Sweden. Firstly, the possibility of providing ancillary services by the wind farms alone are considered with emphasis on the economic profitability. A model is used to present a theoretical maximum of income based on historical production and market data from 2022. The second study has an additional aspect of combining the wind farms with a battery energy storage system (BESS), creating a hybrid system, to examine the potential improvement of income for the company. Due to the production being dependent on weather conditions, the BESS can provide additional contribution when needed. The second study is performed using an optimization model in order to optimize the use of the BESS for the simulated period.

    The results presented an increase of revenues when participating on the ancillary service markets for both studies. The first study showed that down regulating services were the most profitable, this being FCR-D down and aFRR down. With the hybrid system, the profitability was even more significant. It demonstrated a big potential of participating on the FFR market during the summer and FCR-D during winter. Furthermore, the hybrid system also showed an increase in participation on the up-regulating markets. Without the BESS, the windfarm is forced to curtail production toparticipate in the up-regulating markets, which proved to be less profitable than participating on down-regulating markets. The results also give an understanding of the cycling of the BESS and how this affects the results and the BESS lifetime. With coming market development, the conditions on the ancillary service markets is expected to change, the effect of this is considered in a sensitivity analysis. Finally, the studies collectively show the opportunity for wind power to contribute to stabilizing the power system and ensuring the security of energy supply in the Nordicsynchronous system.

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  • 17.
    Abran, Eszter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Andersson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Nilsson Rova, Therese
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Battery Storage for Grid Application: A case study of implementing a Lithium-ion storage system for power peak shaving and energy arbitrage2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Large scale Lithium-ion battery energy storage systems (BESS) for stationary power grid application is a developing field among energy storage technologies. Predictions indicate an increased use of the technology which offers a solution to the challenges that the increasing share of intermittent energy sources causes on the power grid. The non-plannability of intermittent power production requires solutions to maintain a stable and reliable power grid. Further commercialization of BESSes is also seen as use increases for electric vehicles and other mobile use.

    A distribution grid owner, referred to as the Company, has a power subscription for power that is fed from the regional grid, where additional power peak fees are added when exceeding the subscription limit. This study investigates whether a Lithium-ion BESS can be financially beneficial for the Company by examining two power grid services. The first one is power peak shaving, and the second one is energy arbitrage. Energy arbitrage signifies that the BESS is charged during low electricity prices and discharged during high prices, thus generating profit. This is accomplished by simulating a Lithium-ion BESS in MATLAB (2019) where the studied services are combined.

    The results show that a Lithium-ion BESS can be used for the purpose of peak shaving and energy arbitrage, although an investment is not profitable for the Company with the current market situation. The sensitivity analysis does however indicate profitability if the current power peak fees and spot prices remain unchanged while the BESS investment cost is reduced by 50%. This decrease in BESS cost is predicted possible within the next decade as BESS demand is expected to increase. The study implies that the main factor effecting the solution to be profitable is the high investment cost.

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  • 18.
    Abugabbara, Marwan
    et al.
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden.
    Gehlin, Signhild
    The Swedish Geoenergy Center, Lund, Sweden.
    Lindhe, Jonas
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden; Alfa Laval Corporate AB, Lund, Sweden.
    Axell, Monica
    RISE Research Institute of Sweden, Gothenburg, Sweden.
    Holm, Daniel
    Vasakronan AB, Stockholm, Sweden.
    Johansson, Hans
    Umeå ProjektEnergi AB, Umeå, Sweden.
    Larsson, Martin
    RISE Research Institute of Sweden, Gothenburg, Sweden.
    Mattsson, Annika
    Granitor Properties, Malmö, Sweden.
    Näslund, Ulf
    Vasakronan AB, Stockholm, Sweden.
    Puttige, Anjan Rao
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Berglöf, Klas
    ClimaCheck Sweden AB, Nacka, Sweden.
    Claesson, Johan
    Department of Building and Environmental Technology, Division of Building Physics, Lund University, Lund, Sweden.
    Hofmeister, Morten
    Research Center for Built Environment, Energy, Water and Climate, VIA University College, Horsens, Denmark.
    Janson, Ulla
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden.
    Jensen, Aksel Wedel Bang
    Region Midtjylland, Aarhus, Denmark; Department of Planning, Aalborg University, Aalborg, Denmark.
    Termén, Jens
    Energy Machines, Gävle, Sweden.
    Javed, Saqib
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden.
    How to develop fifth-generation district heating and cooling in Sweden?: Application review and best practices proposed by middle agents2023In: Energy Reports, E-ISSN 2352-4847, Vol. 9, p. 4971-4983Article in journal (Refereed)
    Abstract [en]

    Sweden has an ambitious plan to fully decarbonise district heating by 2030 and to contribute with negative emissions of greenhouse gases in 2050. The vagaries of the energy market associated with climate, political, and social changes entail cross-sectoral integration that can fulfill these national targets. Fifth-generation district heating and cooling (5GDHC) is a relatively new concept of district energy systems that features a simultaneous supply of heating and cooling using power-to-heat technologies. This paper presents best practices for developing 5GDHC systems in Sweden to reach a consensus view on these systems among all stakeholders. A mixed-method combining best practice and roadmapping workshops has been used to disseminate mixed knowledge and experience from middle agents representing industry professionals and practitioners. Four successful implementations of 5GDHC systems are demonstrated and the important learned lessons are shared. The best practices are outlined for system planning, system modeling and simulation, prevailing business models for energy communities, and system monitoring. A roadmap from the middle agents’ point of view is composed and can be utilised to establish industry standards and common regulatory frameworks.

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  • 19.
    Achour, Nemer
    Sveriges lantbruksuniversitet.
    Evaluating energy efficiency and emissions of charred biomass used as a fuel for household cooking in rural Kenya2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In sub-Saharan Africa a large share of the energy use utilize biomass as a fuel. In some

    countries more than 90 percent of the energy use is biomass. This energy is primarily used for

    cooking, heating and drying. Cooking food on an open fire or using a traditional stove will

    combust the firewood inefficiently and leads to pollution in the form of particulate matter,

    carbon monoxide and other hazardous pollutants. Indoor pollution has serious health effects

    and especially women and children are affected by this since they spend more time in the

    kitchens compared to men.

    More efficient combustion would lead to less harmful pollution to women and children in

    these rural areas. There are different kinds of stoves on the market and one of them is the

    gasifier stove which allows the biomass to go through pyrolysis in a separate step before

    complete combustion. If the charred biomass is harvested before complete combustion it can

    be saved for later use. This stove will result in cleaner and more energy efficient combustion

    compared to the traditional 3-stone-fire.

    The aim of this study has been to evaluate the charred biomass harvested from this gasifier

    stove in terms of energy use efficiency, emissions and cooking time. The charred biomass was

    compared to conventional charcoal bought at the local market. The charred biomass

    investigated is charred Grevillea prunings from the

    Grevillea Robusta tree, charred coconut

    husks (

    Cocos nucifera) and charred maize cobs (Zea mays). They were tested by cooking a

    meal consisting of two dishes at five different households for different kinds of charred

    biomass and conventional charcoal as a reference.

    Using charred Grevillea prunings gives an energy saving up to 31 percent while charred

    coconut husks gives up to 11 percent energy saved compared to the 3-stone-fire. Charred

    maize cobs was only up to 2 percent more energy efficient than conventional charcoal due to

    its low energy density and fast burning rate. In most cases there was no significant difference

    between the emissions of the different charred fuel types. Only charred maize cobs resulted in

    significantly higher emissions than the other fuels. Household B deviated from the others

    households and had higher emissions. In conclusion the different types of charred biomass are

    good fuels for cooking. Charred maize cobs are less valuable since they require a higher rate

    of refilling of fuel during cooking and do not result in better energy use efficiency compared

    to conventional charcoal.

    There were no significant differences between the different types of charred biomass and

    conventional charcoal in emissions except for a few cases where charred maize cobs had a

    slightly higher level of emission compared to the others. CO

    2- levels were so low that there

    was no risk of harmful concentrations in any way. PM

    2.5-emissions levels were safe, but the

    CO-emissions levels for charred maize cobs were close to levels were symptoms might show.

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  • 20.
    Ackebjer Turesson, Hampus
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems.
    Werneskog, Jesper
    Linköping University, Department of Management and Engineering, Energy Systems.
    The Challenge of Providing Sufficient Grid Capacity for Electrification to Be a Key Factor in Achieving Climate Neutrality Until 2045: A national and regional demand analysis investigating the future electricity demand and the grid operators' perspectives on large-scale electrification in Sweden2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of the thesis is to contribute to grid planning and public debate about how the electric power system can cope with electrification and decarbonisation. The thesis is based on the assumption that Sweden, in accordance with the climate goals, will achieve climate neutrality by 2045.

    Based on a literature review, an analysis is made of how different scenarios predict the future national electricity demand up until 2045 and identifies the underlying drivers for changes in electricity demand. A more detailed analysis based on results from a literature review and interviews with industry representatives is made for four chosen regions, Norrbotten, Västra Götaland, Stockholm and Skåne. For each region, estimates are made of how high the electrification potential is in the industrial, transport, residential and service sectors.

    The prerequisites for the electricity grid to handle the identified electrification potential, in terms of grid capacity, have been analysed in order to highlight what challenges there are for large-scale electrification to be a key factor in achieving the climate goals.

    The general belief in the studied scenarios is that the national electricity demand will increase until 2045. The investigated scenarios predict increases resulting in an annual national electricity demand of up to 207 TWh in 2045, corresponding to an increase of almost 60 %. The most significant increases are due to decarbonisation in the industry and transport sector.

    The regional analysis shows significant electrification potentials in the investigated regions. A few industries stand out with dramatic increases, Borealis AB in Västra Götaland shows an electrification potential of 8 TWh and 1 000 MW and SSAB in Norrbotten shows an electrification potential of 9 TWh and 900 MW. Significant electrification potentials in the transport, residential and service sectors have been identified in metropolitan areas, i.e. in the region of Stockholm, Västra Götaland and Skåne.

    The grid analysis shows that it will be challenging to increase grid capacity at sufficient speed. It is concluded that there is currently insufficient grid capacity to meet large-scale electrification, and that the grids need to be reinforced. However, the concession process for grid reinforcements is considered too slow to meet the demands that arise, primarily in the industry sector. Three ways to address this challenge have been identified:

    -          If the permission process for electricity grid expansion does not change and the industry is to choose the electrification route, this needs to be decided before 2030 in order for reinforcements in the electricity grid to be ensured before 2045.

    -          Speed up the permit process to allow shorter lead times for power grid expansions.

    -          The industry choose another route for decarbonisation than electrification.

    The overall conclusion is that new approaches for expanding the electricity grid will be required if large-scale electrification is to be a key factor in achieving the climate goals in 2045.  

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  • 21.
    Ackeby, Susanne
    et al.
    STRI AB.
    Tjäder, Jonas
    Bastholm, Caroline
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The role and interaction of microgrids and centralized grids in developing modern power systems2017Conference paper (Refereed)
    Abstract [en]

    An extension of microgrids is now underway, primarily to allow increased electrification in growing economies but also to meet the need to reduce global CO2 emissions and to provide ancillary services to centralized grids. Energy access constitutes one of the fundamental building blocks for economic growth as well as social equity in the modern world. Access to sustainable energy is needed to achieve sustainable development. A microgrid should not be seen as a competitor to the centralized grid but as a complement.Through examination of several implemented cases from different parts of the world the following topics are considered: Analysis of the interaction between centralized grids and microgrids Analysis of stakeholder decision parameters for electrification Analysis of design differences and requirements for microgrids, depending on the intended purpose and the need of the end customer.It is determined that good planning, suitable requirements and clear regulations for microgrids (in relation to centralized grids) limits the risk of stranded assets and enables better business cases for the involved stakeholders.The paper is based on the discussion paper The role and interaction of microgrids and centralized grids in developing modern power systems – A case review publiced by ISGAN (International Smart Grid Action Network) Annex 6: Power T&D Systems.The discussion paper and further information about ISGAN is available at http://www.iea-isgan.org/.

  • 22.
    Ackermann, Thomas
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Historical Development and Current Status of Wind Power2012In: Wind Power in Power Systems, Second Edition, John Wiley & Sons, 2012, p. 21-24Chapter in book (Refereed)
    Abstract [en]

    The chapter provides an overview of the historical development (mechanical and electrical power generation) of wind power. It also present the current status of wind power world-wide (capacity installed) together with a discussion of the main drivers for the wind power development, e.g. feed-in tariffs, green certificates etc. Furthermore, the chapter briefly discuss the current trends in wind turbine technology, e.g. larger turbines, and projects development, e.g. offshore wind power.

  • 23.
    Ackermann, Thomas
    KTH. Energynautics GmbH, Germany; Technical University in Darmstadt (TUD), Germany..
    Introduction2012In: Wind Power in Power Systems, Second Edition, Wiley , 2012, p. 1-5Chapter in book (Refereed)
  • 24.
    Ackermann, Thomas
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Wind Power in Power Systems2005Book (Other academic)
    Abstract [en]

    As environmental concerns have focussed attention on the generation of electricity from clean and renewable sources, wind energy has become the world's fastest growing energy source. The authors draw on substantial practical experience to address the technical, economic and safety issues inherent in the exploitation of wind power in a competitive electricity market. Presenting the reader with all the relevant background information key to understanding the integration of wind power into the power systems, this leading edge text: Presents an international perspective on integrating a high penetration of wind power into the power system Offers broad coverage ranging from basic network interconnection issues to industry deregulation and future concepts for wind turbines and power systems Discusses wind turbine technology, industry standards and regulations along with power quality issues Considers future concepts to increase the penetration of wind power in power systems Presents models for simulating wind turbines in power systems Outlines current research activities Essential reading for power engineers, wind turbine designers, wind project development and wind energy consultants dealing with the integration of wind power systems into distribution and transmission networks, this text would also be of interest to network engineers working for power utility companies dealing with interconnection issues and graduate students and researchers in the field of wind power and power systems.

  • 25.
    Ackermann, Thomas
    KTH.
    Wind Power in Power Systems, Second Edition2012Collection (editor) (Refereed)
    Abstract [en]

    The second edition of the highly acclaimed Wind Power in Power Systems has been thoroughly revised and expanded to reflect the latest challenges associated with increasing wind power penetration levels. Since its first release, practical experiences with high wind power penetration levels have significantly increased. This book presents an overview of the lessons learned in integrating wind power into power systems and provides an outlook of the relevant issues and solutions to allow even higher wind power penetration levels. This includes the development of standard wind turbine simulation models. This extensive update has 23 brand new chapters in cutting-edge areas including offshore wind farms and storage options, performance validation and certification for grid codes, and the provision of reactive power and voltage control from wind power plants. Key features: Offers an international perspective on integrating a high penetration of wind power into the power system, from basic network interconnection to industry deregulation; Outlines the methodology and results of European and North American large-scale grid integration studies; Extensive practical experience from wind power and power system experts and transmission systems operators in Germany, Denmark, Spain, UK, Ireland, USA, China and New Zealand; Presents various wind turbine designs from the electrical perspective and models for their simulation, and discusses industry standards and world-wide grid codes, along with power quality issues; Considers concepts to increase penetration of wind power in power systems, from wind turbine, power plant and power system redesign to smart grid and storage solutions. Carefully edited for a highly coherent structure, this work remains an essential reference for power system engineers, transmission and distribution network operator and planner, wind turbine designers, wind project developers and wind energy consultants dealing with the integration of wind power into the distribution or transmission network. Up-to-date and comprehensive, it is also useful for graduate students, researchers, regulation authorities, and policy makers who work in the area of wind power and need to understand the relevant power system integration issues.

  • 26.
    Ackermann, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Holttinen, H.
    Overview of Integration Studies - Methodologies and Results2012In: Wind Power in Power Systems, Second Edition, John Wiley & Sons, 2012, 2, p. 361-386Chapter in book (Refereed)
  • 27.
    Ackermann, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems. Energynautics GmbH, Germany; Technical University in Darmstadt (TUD), Germany.
    Morthorst, P. E.
    Economic Aspects of Wind Power in Power Systems2005In: Wind Power in Power Systems, John Wiley & Sons, 2005, p. 383-410Chapter in book (Other academic)
  • 28.
    Ackermann, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Orths, A.
    Rudion, K.
    Transmission Systems for Offshore Wind Power Plants and Operation Planning Strategies for Offshore Power Systems2012In: Wind Power in Power Systems, John Wiley & Sons, 2012, 2, p. 293-327Chapter in book (Refereed)
    Abstract [en]

    The electric system within an offshore wind power plant and its connection to the main power system pose new challenges to the experts. The best way of interconnecting the wind turbines inside a wind farm has to be found, fulfilling both, redundancy requirements without compromising economic feasibility. The best choice between technologies (HVAC, HVDC - VSC or LCC) for connecting windfarms to shore has to be made, depending on several criteria. The risk of losing this connection versus redundancy has to be economically evaluated. By combining interconnectors and offshore windfarm connections in a modular way, a DC offshore grid can be developed. Anyhow, already during the planning phase the secure operation should be considered thoroughly, because the optimal architecture has to be found, minimizing the necessary assets ensuring secure operation and facilitating later expansion options. The interaction with the onshore grid has to be investigated as well. To enable investigations covering these issues a benchmark offshore test system has been developed which is described in this chapter.

  • 29.
    Ackermann, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    The Value of Wind Power2012In: Wind Power in Power Systems, John Wiley & Sons, 2012, 2, p. 131-155Chapter in book (Refereed)
    Abstract [en]

    The aim of the power plants in a power system is to supply the load in an economical, reliable and environmentally acceptable way. Different power plants can fulfil these requirements in different ways. In order to select the right sources it is important to compare the value of the different sources using an objective approach. The aim of this chapter is describe the different needs of a power system and how these needs can be met with wind power, that is, the value of wind power in a certain system. The values are operating cost value, capacity value, control value, grid loss reduction value and grid investment value. The values can be calculated for different types of power plants, they can be both positive and negative, and they can be calculated both as a physical cost value and a market value.

  • 30.
    Ackermann, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Tröster, E.
    New Control Concept for Offshore Wind Power Plants: Constant-Speed Turbines on a Grid with Variable Frequency2012In: Wind Power in Power Systems, John Wiley & Sons, 2012, 2, p. 345-359Chapter in book (Refereed)
    Abstract [en]

    By using a permanent magnet induction machine as wind generator, the gearbox and converter can be omitted, and the total number of parts reduced leading to a low maintenance and reliable turbine for offshore application. The rotation speed of the turbine however cannot be matched to the wind speed, reducing the energy yield at part load. To overcome this drawback, a central converter can be used, which adjusts the frequency of the local grid in the wind park; this is the so-called park-variable concept. This concept has been compared with respect to energy yield with constant speed and variable speed turbines. Overall, the differences in energy yield of the investigated concepts are so small that other criteria, such as reliability or cost, may be relevant for the selection of one or the other approach. Above all, the park-variable concept represents an interesting alternative to today's common concepts.

  • 31.
    Acuña, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Distributed thermal response tests: New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs.

    Field tests are performed using distributed temperature measurements along U-pipe and coaxial heat exchangers installed in groundwater filled boreholes. The measurements are carried out during heat injection thermal response tests and during short heat extraction periods using heat pumps. Temperatures are measured inside the secondary fluid path, in the groundwater, and at the borehole wall. These type of temperature measurements were until now missing.

    A new method for testing borehole heat exchangers, Distributed Thermal Response Test (DTRT), has been proposed and demonstrated in U-pipe, pipe-in-pipe, and multi-pipe BHE designs. The method allows the quantification of the BHE performance at a local level.

    The operation of a U-pipe thermosyphon BHE consisting of an insulated down-comer and a larger riser pipe using CO2 as a secondary fluid has been demonstrated in a groundwater filled borehole, 70 m deep. It was found that the CO2 may be sub-cooled at the bottom and that it flows upwards through the riser in liquid state until about 30 m depth, where it starts to evaporate.

    Various power levels and different volumetric flow rates have been imposed to the tested BHEs and used to calculate local ground thermal conductivities and thermal resistances. The local ground thermal conductivities, preferably evaluated at thermal recovery conditions during DTRTs, were found to vary with depth. Local and effective borehole thermal resistances in most heat exchangers have been calculated, and their differences have been discussed in an effort to suggest better methods for interpretation of data from field tests.

    Large thermal shunt flow between down- and up-going flow channels was identified in all heat exchanger types, particularly at low volumetric flow rates, except in a multi-pipe BHE having an insulated central pipe where the thermal contact between down- and up-coming fluid was almost eliminated.

    At relatively high volumetric flow rates, U-pipe BHEs show a nearly even distribution of the heat transfer between the ground and the secondary fluid along the depth. The same applies to all coaxial BHEs as long as the flow travels downwards through the central pipe. In the opposite flow direction, an uneven power distribution was measured in multi-chamber and multi-pipe BHEs.

    Pipe-in-pipe and multi-pipe coaxial heat exchangers show significantly lower local borehole resistances than U-pipes, ranging in average between 0.015 and 0.040 Km/W. These heat exchangers can significantly decrease the temperature difference between the secondary fluid and the ground and may allow the use of plain water as secondary fluid, an alternative to typical antifreeze aqueous solutions. The latter was demonstrated in a pipe-in-pipe BHE having an effective resistance of about 0.030 Km/W.

    Forced convection in the groundwater achieved by injecting nitrogen bubbles was found to reduce the local thermal resistance in U-pipe BHEs by about 30% during heat injection conditions. The temperatures inside the groundwater are homogenized while injecting the N2, and no radial temperature gradients are then identified. The fluid to groundwater thermal resistance during forced convection was measured to be 0.036 Km/W. This resistance varied between this value and 0.072 Km/W during natural convection conditions in the groundwater, being highest during heat pump operation at temperatures close to the water density maximum.

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    José Acuña - Doctoral Thesis
  • 32.
    Acuña, José
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Distributed thermal response tests on pipe-in-pipe borehole heat exchangers2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 109, no SI, p. 312-320Article in journal (Refereed)
    Abstract [en]

    Borehole Thermal Energy Storage systems typically use U-pipe Borehole Heat Exchangers (BHE) having borehole thermal resistances of at least 0.06 K m/W. Obviously, there is room for improvement in the U-pipe design to decrease these values. Additionally, there is a need for methods of getting more detailed knowledge about the performance of BHEs. Performing Distributed Thermal Response Tests (DTRT) on new proposed designs helps to fill this gap, as the ground thermal conductivity and thermal resistances in a BHE can be determined at many instances in the borehole thanks to distributed temperature measurements along the depth. In this paper, results from three heat injection DTRTs carried out on two coaxial pipe-in-pipe BHEs at different flow rates are presented for the first time. The tested pipe-in-pipe geometry consists of a central tube inserted into a larger external flexible pipe, forming an annular space between them. The external pipe is pressed to the borehole wall by applying a slight overpressure at the inside, resulting in good thermal contact and at the same time opening up for a novel method for measuring the borehole wall temperature in situ, by squeezing a fiber optic cable between the external pipe and the borehole wall. A reflection about how to calculate borehole thermal resistance in pipe-in-pipe BHEs is presented. Detailed fluid and borehole wall temperatures along the depth during the whole duration of the DTRTs allowed to calculate local and effective borehole thermal resistances and ground thermal conductivities. Local thermal resistances were found to be almost negligible as compared to U-pipe BHEs, and the effective borehole resistance equal to about 0.03 K m/W. The injected power was found to be almost evenly distributed along the depth.

  • 33.
    Adesanya, Adewale A.
    et al.
    Energy and Environmental Analysis Group, New York State Energy Research and Development Authority (NYSERDA), Albany, NY, 12203, USA; Havenergy Consulting Inc, Albany, NY, 12203, USA.
    Sommerfeldt, Nelson
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Pearce, Joshua M.
    Department of Electrical and Computer Engineering, Ivey School of Business, University of Western Ontario, London, ON, N6A 5B9, Canada.
    Achieving 100% Renewable and Self-Sufficient Electricity in Impoverished, Rural, Northern Climates: Case Studies from Upper Michigan, USA2022In: Electricity, E-ISSN 2673-4826, Vol. 3, no 3, p. 264-296Article, review/survey (Refereed)
    Abstract [en]

    The development of 100% renewable electricity (RE) systems play a pivotal role in ensuring climate stability. Many municipalities blessed with wealth, an educated and progressive citizenry, and large RE resources, have already reached 100% RE generation. Impoverished municipalities in unwelcoming environments both politically and climatically (e.g., northern latitudes with long, dark winter conditions) appear to be incapable of transitioning to renewables. This study challenges that widespread assumption by conducting a detailed technical and economic analysis for three representative municipalities in the Western Upper Peninsula of Michigan. Each municipality is simulated with their own hourly electricity demand and climate profiles using an electrical supply system based on local wind, solar, hydropower, and battery storage. Sensitivities are run on all economic and technical variables. Results show that transition to 100% RE is technically feasible and economically viable. In all baseline scenarios, the 100% RE systems produced a levelized cost of electricity up to 43% less than the centralized utility rates, which are predominantly fueled by gas and coal. Current policies, however, prevent such self-sufficient systems from being deployed, which are not only detrimental to the global environment, but also aggravate the economic depression of such regions. Potential energy savings advance the prohibitive energy justice principle.

  • 34.
    Adolfsson, Antonia
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Off grid boende: Dimensionering samt värdering av möjliga system för hantering av avlopp och energiförsörjning2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Bostadsbristen är ett ständigt faktum i Sverige idag och i takt med att boendepriserna ökar så ökar också intresset för att bygga sin egen bostad. Arkitektfirman Tengbom i Karlstad har startat upp ett projekt, Portable Empowerment, som bygger på visionen om att skapa en portabel bostad som ska kunna fungera som en lösning när ett plötsligt behov av bostäder uppstår. För att bostäderna ska kunna flyttas runt krävs det att lösningar för energi- och avloppssystem finns integrerade i bostaden och ska kunna flyttas med för att göra bostaden portabel. För att detta ska vara möjligt krävs det avlopps- och energisystem som är off grid.

    Off grid betyder att systemet inte är kopplat till kommunalt avlopp eller elnät. Det finns sedan länge sätt att lösa både avlopp och energiförsörjning off grid och några exempel där det tillämpas är husvagnen och den klassiska sommarstugan, men de är allt som oftast inte anpassade för bruk året runt. Målet med denna studie är att identifiera samt värdera avlopps- och energisystem som kan tillgodose behoven i en liten bostad som brukas året runt av två personer. Bostaden har sin utgångspunkt i de ritningar som tagits fram av Tengbom för deras projekt Portable Empowerment.

    För att identifiera system som kan tillgodose behoven i bostaden har modeller byggts upp och simuleringar skett där system lämpade för off grid inkluderats. Lösningarna har sedan jämförts med varandra med hjälp av värderingsmatriser där portabilitet, kostnad, miljö och användarvänlighet för varje system värderats.

    Resultatet av studien visar att det finns flera system för både energi och avlopp som kan tillgodose behoven i bostaden året om. Flera av systemen uppfyller kraven för en portabel bostad och det är med andra ord möjligt att uppfylla Tengboms vision om ett fullständigt portabelt boende. Jämfört med en ”vanlig” bostad som är ansluten till vatten- och elnät är dock off grid-lösningarna betydligt mer tidskrävande. Genom att installera ett eget system med lösningar för enbart den egna bostaden tar brukaren också på sig det fulla ansvaret, något som kan tänkas vara en belastning för vissa brukare och en frihet för andra.

    Ur ekonomisk synpunkt visar studien att på energisidan är det svårt att hitta ett off grid-system som är billigare än on grid-systemet där en luftvärmepump installerats. Däremot är anslutningen till ett kommunalt avlopp betydligt dyrare, mellan 100 000-150 000 kronor mer, än att anlägga till exempel en egen infiltrationsanläggning i anslutning till den egna bostaden.

    För att utveckla denna studie bör möjligheten att bygga off grid-byar undersökas. Genom att bygga upp ett samhälle om ett stort bostadsbehov skulle uppstå kan energi- och avloppsanläggningar delas. Anläggningarna har större kapacitet och genom att dela på dessa kan både ansvar och kostnad minskas.

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  • 35.
    Adolfsson, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Characterization of combinatorial Cu2ZnSnS4 thin films2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The kesterite Cu2ZnSnS4 (CZTS) is considered as a possible absorber layer in future photovoltaic (PV) applications. The abundance of its constituent elements along with the material being non-toxic and having a direct band gap of around 1.5 eV make it an attractive material for solar cell applications. So far, cells with an efficiency of 12.6 % have been achieved. The limiting factor is the finished cells' open circuit voltage (VOC) deficit which has been attributed to structural defects in the material. Problems with sustaining a sulfur-enriched atmosphere during the annealing step of material production have been observed, and are thought to be partially responsible for the high density of structural defects. Elemental sulfur is commonly used for inducing a sulfur-enriched atmosphere in the anneal. In this study, four combinatorial and polycrystalline CZTS thin films were prepared and annealed in different conditions with regards to time, sulfur source and amount. The samples were characterized using energy dispersive-, Raman- and photoluminescence spectroscopy. The effect of the anneal on the different composition regions were analyzed and secondary phases were identified. Introducing CuS as the sulfur source during the anneal reduced the decomposition of the CZTS phase, and lowered the density of the defect complex [ZnCu + CuZn], while enlarging the single phase region. Strictly and highly Sn-rich compositions of CZTS was observed to yield both high cation order and photoluminescence intensity, and a link between the two parameters was observed.

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  • 36.
    Adolfsson, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Expanding operation ranges using active flow control in Francis turbines2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report contains an investigation of fluid injection techniques used in the purpose of reducing deleterious flow effects occurring in the draft tube of Francis turbines when operating outside nominal load. There is a focus on implement ability at Jämtkrafts hydroelectric power plants and two power plants were investigated, located in series with each other named Lövhöjden and Ålviken. The only profitable scenario found with some degree of certainty was an increase in the operating range upwards to allow overload operation.

    Findings show that both air and water can be introduced in various locations to improve hydraulic efficiency around the turbine parts as well as reduce pressure pulsations in harmful operating regions. Investments in such systems have proven useful and profitable at several facilities with poorly adapted operating conditions. But due to losses in efficiency when operating injection systems, it turns out unprofitable in situations where it does not improve the operating range in a way that is resulting in increased annual or peak production.

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    Lastområdesutvidgning med aktiv flödeskontroll i Francisturbiner
  • 37.
    Aftab, Mohammad Adnan
    Halmstad University, School of Business, Engineering and Science.
    Biofuel, An alternative source for jet fuel in Aviation2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The transport industry is one of the fastest growing industries with the sector playing a significant role in negative impact on global warming and pollution through the emission of greenhouse gases. Aviation in particular, has enjoyed growth especially in the few decades. New airlines and aircraft manufacturers are coming up with different innovations and technologies to ensure they make the best possible environmentally friendly aircraft. The new main area of focus has been on how to come up with fuel that will reduce the greenhouse gas-emissions. The stakeholders in the same effort include developed nations like the United States, United Kingdom, Russia, France, Germany, and Canada among others. Energy providers as well as jet fuel suppliers are also making efforts to conserve the environment. The purpose of this thesis is to explore the area of biofuel in aviation by looking into various stakeholders involved in the efforts of the transition from fossil fuel to biofuel. The conclusion of this thesis is that biofuels are viable options in the aviation industries since there have been positive results in the tests made. 

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  • 38.
    Aga, Aboma Emiru
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fuel Supply Investigation for an Externally Fired Microturbine based Micro CHP System: Case study on a selected site in Bishoftu, Ethiopia2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sudden change on earth’s climate, which is a result of an increase in CO2 in the atmosphere, is mainlycaused by burning of fossil fuels for various energy services. However, for the energy services to befavourable to the environment, there should be a balance with the environmental protection, and we cancall that “Sustainable Innovative Development”.

    “EXPLORE Polygeneration” initiative will serve as an important tool to promote the application ofrenewable technologies extending to the future sustainable energy engineering field. This paper is intendedin investigating a suitable fuel supply for the microturbine based micro CHP system available at theDivision of Heat and Power Technology, KTH, Sweden; for a site called “Alema Farm PLC”, Bishoftu,Ethiopia.

    Though there is a large biomass energy resource and a huge potential to produce hydroelectric power inEthiopia, the modern energy sector is very small and the energy system is mainly characterized by biomassfuel supplies and household energy consumption. The nation’s limited biomass energy resource is believedto have been depleting at an increasingly faster rate.

    Of the many and surplus amount of renewable energy resources available in and around Alema FarmPLC, poultry litter and pig’s manure are selected to be the two main energy sources for the CHP systemavailable in the lab, after passing through different conversion techniques. However, after consideringsome basic properties like: Energy content and Bulk Density of the fuel, Moisture content , Ashcharacteristic, Tar content, Fuel logistics, Local storage, Fuel feeder system, and Magnitude of GHGReduction; poultry litter is found to be the most convenient to produce a syngas with a Downdraftatmospheric gasifier available in the HPT lab.

    Finally, For the problems caused by the nature of the poultry litter by itself and the methods used in theconversion process, the 40 TRIZ principles of TRIZ inventive principles is used and some major pointsare recommended.

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    Fuel Supply Investigation for an Externally Fired Microturbine based Micro CHP System
  • 39.
    Agerhäll, Isabella
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Flexibilitet i elsystemet: En undersökning om hur flexibilitet lokalt kan samverka med de nationella stödtjänstmarknaderna2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Swedish power system is facing a lot of change in the near future. A system which is built around nuclear- and hydropower now contains more and more intermittent power sources such as wind and solar. In addition, Sweden is entering a second electrification era, where the electricity use is predicted to increase substantially. This means the need for flexibility in the power system is bigger than ever and is going to increase.

    The power system needs to be in balance at every instance. The same amount of energy that is produced also needs to be consumed. This balance, or imbalance, affects the frequency in the system and there are balancing markets in place to handle disturbances in the frequency.Flexible solutions outside these balancing markets can also be valuable since they can lower costs for power use and prevent unnecessary investments in the power grids.

    This thesis was written in cooperation with the municipal energy company Gävle Energi. The cases it is built on are both cases in and around Gävle. The study is based on two cases: One case where a local hauling company is interested in a combination of solar power, electric charging for vehicles, and a battery storage. The hauling company plans to electrify parts of their fleet and will by doing so increase their power use. The second case regards the building of a gasturbine for electricity production in Gävle Energi’s grid.

    Both cases examine how the balancing markets can be used to motivate investments in flexible solutions. The hauling company can lower their power peaks by using a battery storage and the battery storage can also be used to sell capacity on the balancing market FCR-D. Through planning when heavy duty charging and regular vehicle charging is done, unnecessary power peaks can be avoided. The study shows that a battery storage can in fact be profitable and bring benefits to both the hauling company and the national energy system.

    The second case, the gas turbine, is based on income from both the spot market and the balancing market mFRR which is then compared to the price for gas. The income from mFRR was varied between 140-250% of the prices from 2021 and the gas price was varied from 800-2100 SEK. The results show that the prices for mFRR need to increase a lot for the turbine to be profitable and the gas turbine could perhaps be more beneficial if combined with other solutions. The case has a lot of insecurities as the turbine runs very few hours per year (only 10 hours would have been profitable in 2021). It becomes vital that the bidding is won these hours, which is hard to predict.

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    Flexibilitet_i_elsystemet
  • 40.
    Aguirre Sánchez, Mikel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Air flow disturbance by moving objects at local exhaust ventilation2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The present thesis aims to study the effect of human movements on local exhaust ventilation.

    In its simplest terms, local exhaust ventilation is a system which has the function of extracting contaminated air situated close to the contaminant source, protecting a working person from exposure to hazardous substances by containing or capturing them locally, at the emission point. As an important security measure referred to terms of health, it is crucial for the healthiness of workers to control and prevent them from the exposure to vapour, mist, dust or other airborne contaminants. Additionally, to a lesser degree of significance, it can be stressed an expected increase in worker performance due to an improvement of the working conditions.

    There is an existing necessity for well-defined and appropriate methods to test the performance of local exhaust devices in order to reach standard efficiency values. The lack of an international standardization led to the realization of this study, which, ultimately, has the purpose of obtaining relevant results that can be utilized for future normalized test procedures.

    The study entails full scale experimental measurements that include air velocity measurements in 3 dimensions, a local exhaust ventilation device with circular hood and a flat flanged plate and a controlled generation of air turbulence through physical movements of a human-sized cylinder, simulating a walking person.

    The present study extends previous similar studies at the University of Gävle, where the controlled air turbulence was generated by a moving plate. After meaningful results obtained in that study, one of the considerations was to better simulate a walking person, by replacing the plate for a movable cylinder. The present study points at a larger similarity occurring with a cylinder than with a plate, as regards the air flow pattern produced by a real walking person.

    As in the previous study, the Percentage of Negative Velocities, PNV, has been used as the main measure of turbulence induced risk of contaminant spread. The PNV represents the fraction of the time when the flow is directed opposite to the suction air stream in front of the local exhaust hood. The obtained results conclude that the use of the cylinder as a moving object has been an improvement to simulate the effect of the movement of a human being on a relaxed walking pace.

    The present study was carried out in parallel with the thesis work by Leyre Catalán Ros, which complements this study by analyzing the effect of an added heated dummy, simulating a person seated in front of the local exhaust device.

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  • 41.
    Agyekum, Ephraim Bonah
    et al.
    Ural Fed Univ, Russia.
    Ampah, Jeffrey Dankwa
    Tianjin Univ, Peoples R China.
    Khan, Tahir
    Zhejiang Univ, Peoples R China.
    Giri, Nimay Chandra
    Centurion Univ Technol & Management, India; Centur Univ Technol & Managemention, India.
    Hussien, Abdelazim
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering. Fayoum Univ, Egypt; Appl Sci Private Univ, Jordan; Middle East Univ, Jordan.
    Velkin, Vladimir Ivanovich
    Ural Fed Univ, Russia.
    Mehmood, Usman
    Bahcesehir Cyprus Univ, Turkiye; Univ Punjab, Pakistan.
    Kamel, Salah
    Aswan Univ, Egypt.
    Towards a reduction of emissions and cost-savings in homes: Techno-economic and environmental impact of two different solar water heaters2024In: Energy Reports, E-ISSN 2352-4847, Vol. 11, p. 963-981Article in journal (Refereed)
    Abstract [en]

    South Africa currently has the highest carbon emission intensity per kilowatt of electricity generation globally, and its government intends to reduce it. Some of the measures taken by the government include a reduction of emissions in the building sector using solar water heating (SWH) systems. However, there is currently no study in the country that comprehensively assesses the technical, economic, and environmental impact of SWH systems across the country. This study therefore used the System Advisor Model (SAM) to model two different technologies of SWH systems (i.e., flat plate (FPC) and evacuated tube (EPC) SWH) at five different locations (i.e., Pretoria, Upington, Kimberley, Durban, and Cape Town) strategically selected across the country. According to the study, the optimum azimuth for both the evacuated tube and flat plate SWH system in South Africa is 0 degrees. Installing FPC and EPC at the different locations would yield payback periods of 3.2 to 4.4 years and 3.5 to 4.3 years, respectively. Comparably, levelized cost of energy for the FPC and EPC will range from 7.47 to 9.62 cents/kWh and 7.66 to 9.24 cents/kWh, respectively, based on where the SWH system is located. Depending on where the facility is located, the annual cost savings for the FPC system would be between $486 and $625, while the EPC system would save between $529 and $638. Using SWHs can reduce CO2 emissions by 75-77% for the evacuated tube system and 69-76% for the flat plate system annually, depending on the location.

  • 42.
    Ahl, Amanda
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Eklund, Johanna
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Yarime, M.
    Balancing formal and informal success factors perceived by supply chain stakeholders: A study of woody biomass energy systems in Japan2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 175, p. 50-59Article in journal (Refereed)
    Abstract [en]

    Small-scale woody biomass energy systems have an inherent ability to aid in emissions reduction while stimulating local economies and, as collective energy systems, are strongly connected to supply chain design based on local conditions and stakeholder integration. Despite an abundance of forest area alongside the promotion of biomass in energy policies, however, woody biomass utilization still remains low in Japan. The woody biomass supply chain, considered as a socio-technical system, involves a complex, cross-sectoral stakeholder network in which inter-organizational dynamics necessitates well-organized management based on an understanding of formal factors such as technology, as well as informal factors such as social relations and culture. In this paper, success factor perceptions from across the woody biomass supply chain are investigated based on semi-structured interviews with four stakeholders in the Kyushu region of Japan. Identified success factors here are: 1) respect of values & traditions, 2) transportation infrastructure, 3) business model integration, 4) relationship & trust, 5) local vitalization and 6) biomass quality control. A convergence as well as divergence of perceptions are observed, involving both formal and informal dimensions. Aiming to balance perceptions and to enable long-term success of woody biomass in Japan, a series of policy implications are drawn, including cross-ministerial integration, knowledge building on wood logistics, forest certification, local coordinators, biomass quality control standards and a feed-in-tariff for heat. This paper suggests a new arena of policy-making based on the importance of considering both informal and formal dimensions in energy policy.

  • 43.
    Ahlberg, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Georges, Elza
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Norlén, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    The potential of hemp buildings in different climates: A comparison between a common passive house and the hempcrete building system2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this bachelor thesis was to study the potential of hemp buildings in different climates. The report examines and models two different energy efficient building concepts – the more common passive house and the environmental friendly hempcrete building system. These two buildings thermal performances were then simulated and compared in different climates followed by a brief discussion about their economic and environmental impact.

    The simulation was performed with the energy calculating program VIP-energy v 2.1.1 with the two models located in Kiruna, Sundsvall, Malmo, Berlin and Rome to represent the different climates. Simulations for different wall sizes and a sensitivity analysis of some significant parameters were also made.

    The hempcrete building system showed to have a thermal performance similar to that of passive houses in more southern climates. In the north of Sweden however the hempcrete building required up to 20 % more energy than the passive house to maintain comfortable indoor temperatures. This deficit could be compensated for with hemp fibre insulation to augment the building envelope and U-value. Furthermore the hygrothermal material properties that were not included in the simulation can be expected to have a significant positive impact on hemp buildings relative thermal performance.

    With a passive house thermal performance, a healthy indoor environment and an economically viable and environmental friendly production process hemp building demonstrated great potential in all the fields studied.

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    The potential of hemp buildings in different climates
  • 44.
    Ahlfors, Charlotta
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Amelin, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Weekly planning of hydropower in systems with large volumes and varying power generation: A literature review2021In: 2021 IEEE Madrid PowerTech, PowerTech 2021 - Conference Proceedings, Institute of Electrical and Electronics Engineers (IEEE) , 2021, article id 9495058Conference paper (Refereed)
    Abstract [en]

    Hydropower is the world's largest source of renewable electricity generation and hydropower plants with reservoirs provide flexibility to the power systems. Efficient planning techniques improve the flexibility of the power systems and reduce carbon emissions, which is needed in power systems exposed to a rapid change. Renewable energy sources, such as wind and solar power, are increasing in the power systems. Hydropower plants have low operating costs and are used as base power. This paper reviews hydropower planning in different time frames and specifically focuses on weekly planning, i.e. hydropower planning for 1 to 3 weeks. Main conclusions in this study are that the term weekly planning is seldom used and the definitions in earlier studies of short term, mid term and long term planning, respectively, varies. The authors propose that weekly planning should belong to mid term planning.

  • 45. Ahlm, Niklas
    Laststyrning av eluppvärmning och varmvattenberedning: En studie av potentialen för hushåll att bidra till en sänkt abonnerad effekt mot överliggande elnät2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study has explored the potential for lowering the subscripted power of 25 MW for one of the connection points between the local power grid and its overhead power grid for a local grid owner. The potential for doing so through hard, direct load control of electrical domestic heating and domestic water heating for detached houses with a fuse size of 16-25 A is evaluated for 12 different scenarios. The scenarios are found by combining a customer participation of 25, 50, 75 and 100 percent with a maximum allowed duration for load control of two, three and four hours respectively. A function describing the need for electrical power for domestic heating as dependent of the outdoor temperature is developed and combined with a model that is used for simulating hot water usage and a model that describes the power demand of a domestic water heater. Furthermore, a control function is incorporated to ensure that households are not subjected to load control for a longer period than allowed and that all households bear the same burden in this respect. 

    The results show that a power of 1,0-4,1 MWh/h can be redistributed, but that the potential is heavily limited by the returning load that occurs. Due to the long duration of the critical peaks that are being redistributed, up to 5-10 hours, returning load occurs even though load control has not yet been finalized. The returning load leads to a bigger amount of power having to be redistributed and therefore limits the potential for the new subscripted power that can be achieved. Furthermore, the maximum aggregated power for the investigated year amounts to 25,9 MW. Still, a new subscripted power of 21,8–24,9 MW is theoretically deemed to be achievable. The most likely outcome however is thought to be a lowering of the subscripted power to at least 23,4–24,4 MW, having taken the composition of type of heating systems as well as the most likely customer participation into account. 

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    Laststyrning av eluppvärmning och varmvattenberedning: En studie av potentialen för hushåll att bidra till en sänkt abonnerad effekt mot överliggande elnät
  • 46.
    Ahlström, Johan
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Corrosion.
    Jafri, Yawer
    Luleå University of Technology, Sweden.
    Wetterlund, Elisabeth
    Luleå University of Technology, Sweden; International Institute for Applied Systems Analysis, Austria.
    Furusjö, Erik
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy. Luleå University of Technology, Sweden.
    Sustainable aviation fuels – Options for negative emissions and high carbon efficiency2023In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 125, article id 103886Article in journal (Refereed)
    Abstract [en]

    Mitigating the climate impact from aviation remains one of the tougher challenges in adapting society to fulfill stated climate targets. Long-range aviation cannot be electrified for the foreseeable future and the effects of combusting fuel at high altitude increase the climate impact compared to emissions of green-house gasses only, which further limits the range of sustainable fuel alternatives. We investigate seven different pathways for producing aviation biofuels coupled with either bio-energy carbon capture and storage (BECCS), or bio-energy carbon capture and utilization (BECCU). Both options allow for increased efficiency regarding utilization of feedstock carbon. Our analysis uses process-level carbon- and energy balances, with carbon efficiency, climate impact and levelized cost of production (LCOP) as primary performance indicators. The results show that CCS can achieve a negative carbon footprint for four out of the seven pathways, at a lower cost of GHG reduction than the base process option. Conversely, as a consequence of the electricity-intensive CO2 upgrading process, the CCU option shows less encouraging results with higher production costs, carbon footprints and costs of GHG reduction. Overall, pathways with large amounts of vented CO2, e.g., gasification of black liquor or bark, as well as fermentation of forest residues, reach a low GHG reduction cost for the CCS option. These are also pathways with a larger feedstock and corresponding production potential. Our results enable a differentiated comparison of the suitability of various alternatives for BECCS or BECCU in combination with aviation biofuel production. By quantifying the relative strengths and weaknesses of BECCS and BECCU and by highlighting cost, climate and carbon-efficient pathways, these results can be a source of support for both policymakers and the industry. © 2023 The Author(s)

  • 47.
    Ahlund, Viktor
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energikartläggning av förskolan Smultronstället2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is an energy audit with recommended energy efficient solutions recommended made on a preschool in north Gävle. This preschool is administrated by Gavlefastigheter. In Sweden almost 40 % of Sweden’s energy supply goes to the housing and service sector. This means there is a lot of potential to save energy in this field. A good way to start saving energy in a building is to do an energy audit.This energy audit is made from blueprints of the building, real measurements, standard values, assumptions, and literature.The school has a calculated energy use of 1239 MWh per year; this is divided on ventilation, transmission losses and hot tap water. A calculation with energy efficient solutions makes a total of 612 MWh or 49, 4 % in saved energy. The energy efficient savings calculated are new windows, additional insulation and changed ventilation. To only change the ventilation made for an energy saving of 522 MWh which is 42, 1 % from the total energy use in the building. To change the ventilation to an FTX-system is the recommended change to be made.

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  • 48.
    Ahlvin, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Arriaga, Yasmine
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Bauman, Elise
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Berglund, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Magnusson, Clara
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Wiklund, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Energiomställning Gotland: Alternativ för att nå ett förnybart energisystem2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sammanfattning

    Syftet med denna studie är att i åtta scenarier konkretisera hur Gotland skulle kunna ställa om till en förnybar energiförsörjning. Detta ska visa vägen för hela Sveriges omställning till förnybar energi 2040. Studien ska tjäna som en första orientering av vad fortsatt forskning kan inriktas på. Metoden var främst litteraturstudie samt modellering och beräkningar utifrån representativa exempel. Bedöm- ning av alternativ gjordes utifrån de övergripande kriterierna hållbarhet, resurseffektivitet och realis- tisk potential. Som begränsning utgick studien från åtta scenarion med olika förutsättningar och olika fokus. Tidsramen var fram till 2030.

    Scenario 1 - Transport: I scenario 1 var fokus att göra transportsektorn förnybar. Biogas och el från vind- kraft ansågs vara de energikällor som bäst ersätter de fossila bränslena. Import av biodiesel bedömdes även nödvändig, framför allt till tung transport. Utmaningen ligger främst i den omfattande omställ- ningen som krävs av fordonsflottan.

    Scenario 2 - Industri: I scenario 2 fokuserades endast på industrins omställning till förnybar energi. Framför allt cementproducenten Cementa använder en stor andel av Gotlands energi. Alternativet med störst potential, och som bör prioriteras för fortsatta studier, ansågs vara att att elektrifiera Ce- menta.

    Scenario 3 - Bioenergi: I scenario 3 skulle bioenergi användas för att ersätta fossila bränslen, samtidigt som Gotland var självförsörjande på livsmedel. Industrin bortsågs ifrån. De två intressena visade sig vara förenliga.

    Scenario 4, 5 och 6 - Reglering: Scenario 4, 5 och 6 fokuserar alla på olika typer av energilagring och reglering. Detta är nödvändigt i ett energisystem som till stor del bygger på vindkraft och solenergi. Batteriparker, tryckluft, pumpkraft och vätgas studerades som möjliga lagringsmetoder. Främst bat- terier i kombination med vätgas ansågs ha potential på Gotland. Fortsatt breda studier krävs dock.

    Scenario 7 - Ingen kabel: Idag finns en kabel mellan Gotland och fastlandet för import och export av elektricitet. I scenario 7 kan den kabeln inte användas. Stor utbyggnad av vindkraften krävs då, spe- ciellt havsbaserad. För att lättare reglera energin föreslogs att Gotland delas in i mindre system.

    Scenario 8 - Energiplan 2020: Region Gotland har satt upp mål för energisystemet år 2020 i Energiplan 2020. I scenario 8 studerades hur energisystemet skulle kunna se ut om målen uppfylldes. Stora för- ändringar från dagens energisystem skulle krävas.

    Slutsatsen av studien var att fortsatta studier främst ska riktas mot möjliga lagringstekniker, indu- strins energiförsörjning samt samhällets inställning till en energiomställning. Lagringstekniker är en förutsättning för den storskaliga utbyggnad av vindkraft som är nödvändig och som finns potential för. Grundläggande för att nå ett förnybart energisystem är hela samhällets delaktighet. Att kartlägga allmänhetens drivkrafter och motsättningar är därför viktigt.

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  • 49.
    Ahmad, Iftikhar
    et al.
    Natl Univ Sci & Technol, Pakistan.
    Arif, Muhammad Salman
    Natl Univ Sci & Technol, Pakistan.
    Cheema, Izzat Iqbal
    Univ Engn & Technol, Pakistan; Univ Engn & Technol, Pakistan.
    Thollander, Patrik
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Khan, Masroor Ahmed
    United Nations Ind Dev Org, Pakistan.
    Drivers and Barriers for Efficient Energy Management Practices in Energy-Intensive Industries: A Case-Study of Iron and Steel Sector2020In: Sustainability, E-ISSN 2071-1050, Vol. 12, no 18, article id 7703Article in journal (Refereed)
    Abstract [en]

    The two major reasons behind the worlds energy crisis are losses in energy transmission and less efficient energy use at sinks. The former flaw can be catered by changing the entire energy transmission system which requires investment and planning on a large scale, whereas the later deficiency can be overcome through proper management of energy utilizing systems. Energy-intensive industries have a substantial share in energy consumption and equally high energy saving potentials if they adopt some integrated and improved energy efficiency. This study investigates the energy management systems in the iron and steel sector of Pakistan, and compare it with findings of similar work in Sweden, Bangladesh, and Ghana. A systematic questionnaire was circulated in the iron and steel sector across the country and afterward the collected data was analyzed to find major barriers and drivers for efficient energy management practices. In addition, questions on non-energy benefits and information sources relevant to the energy efficiency were also part of the questionnaire. Cost reduction resulting from lowered energy use was rated as the most important driver for applying energy-efficient operation. On the other hand, the cost of production disruption was considered among high-level barriers to the implementation of improved energy efficiency. An increase in the life-time of equipment was labeled as the top non-energy benefits. Company peers and seminars/conferences were referred as the best information sources related to energy efficiency. The outcome of the study will be helpful to the decision-maker in the industry, as well as the government levels.

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  • 50.
    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 batteries2021In: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution, Institution of Engineering and Technology, 2021, p. 2104-2108, article id 0713Conference paper (Refereed)
    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.

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