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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Lönsamheten för batterier och solceller i framtiden / The profitability of batteries and solar cells in the future

Salomonsson, Elsa, Huang, Linnea January 2023 (has links)
Ensuring a balance between energy production and consumption has become a significant challenge in today’s society. One possible solution is the use of batteries as energy storage. With the growing demand for residential batteries, it is of interest to investigate their profitability, both presently and in the future. The objective of this thesis is therefore to assess the profitability of residential battery storage for various investment years and to compare the economic viability of using batteries alone, solar cells alone, or a combination of both. To achieve this goal it is essential to develop a battery model that accurately simulates battery cell degradation. In this thesis, a fully implemented battery simulation model from Oxford is used.  Additionally, two optimization models are constructed: one that optimizes the utilization of a standalone battery, and another that optimizes the usage of a battery in combination with solar cells. The third model, regarding only solar cells, is not an optimization model. It is a profitability model that calculates the expected profit based on the forecasted electricity prices and expected generated power from the solar cells. The final profitability of the three alternatives for each investment year is determined by calculating the Net Present Value (NPV) using the NPV formula. Further, it is crucial to consider uncertain factors such as differences in investment costs or discount rates, as they might have an impact on the results. To address this uncertainty, a sensitivity analysis is conducted to explore a wider range of possible outcomes.  The results indicate that using batteries alone does not yield profitable outcomes whereas owning only solar cells generates significantly higher profits, with a maximum repayment period of seven years. Combining them both is currently not profitable but it could become profitable in a couple of years. The results from the sensitivity analysis indicate that both the investment costs as well as the discount rate highly effect the results.  One assumption regarding the future is that the use of solar cells will continue to grow, given their demonstrated high profitability. Whether residential batteries will experience a breakthrough will likely depend of a range of factors, including both economical and non- economical considerations. Economical factors will influence the growth of residential batte- ries based on batteries advancements, cost reductions, and the overall economic climate. On the other hand, non-economic factors will also impact the growth of residential batteries. Examples of these factors are the energy crisis, the urge for independence and the development of optimization services that aim to optimize the residents’ profitability.
482

LCA på byggnaden och dess installationer : Utsläpp av växthusgaser vid produktion av isolering kontra energianvändningen i nya byggnader / LCA on the building and its installations : Greenhouse gas emissions in the production of insulation versus the energy use in new buildings

Lindholm, Helena, Dahlby, Susanne January 2023 (has links)
Byggsektorn står idag för en femtedel av Sveriges totala utsläpp av koldioxidekvivalenter (CO2e) och har i det närmaste varit oförändrad medan energianvändningen i byggnader har minskat över tid. Även byggnadens installationer har förbisetts trots att de står för en betydande andel av utsläppen kopplat till en byggnads livscykel. Genom att göra beräkningar i form av en livscykelanalys på en byggnad kan aktiviteter där utsläppen uppstår identifieras och åtgärder prioriteras. Syftet med studien var att göra en livscykelanalys på isoleringsmaterial i huskroppen samt dess VVS-installationer på en nybyggnation av en förskola i Sundbyberg, för att se hur isoleringstjockleken påverkar CO2e-utsläppen samt jämföra det med energianvändningens CO2e-utsläpp som sparas in vid mer isolering. För att kunna jämföra byggnadens energibehov med olika tjocklekar på isoleringen skapades ett flertal modeller. Energibehovet täcktes upp av olika energikällor och leverantörer för att kunna studera vilken inverkan det har på utsläppen när dessa variabler förändras. Det skapades även ett teoretiskt framtidsscenario där el- och fjärrvärmesektorn går mot nollutsläpp år 2045. För installationerna valdes ett annat tillvägagångsätt på grund av brist på information inom området. Ett verktyg för rör och kanalers isolering utvecklades för att kunna utföra beräkningar på dess CO2e-utsläpp och jämföra det med värmeförlusternas utsläpp. Beroende på val av energikälla varierade resultatet, när mindre isolering valdes gynnades utsläppen av de lokala energikällorna, men sett till Boverkets generiska värden uppstod en brytpunkt efter 15 år där val av mer isolering gjorde att de totala CO2e-utsläppen minskade under en 60-årsperiod. För framtidsscenariot visade det sig i båda fallen att mindre isolering var det bättre alternativet sett över samma period. Resultatet påverkas även av de begränsningar som studien förhållit sig till, exempelvis har ingen hänsyn tagits till de sekundära effekterna så som det förlängda bjälklaget vilket blir en naturlig effekt av att isolera mer. Utsläpp kopplat till byggsektorn måste börja minska för att nå Sveriges klimatmål om att bli klimatneutrala till år 2045. / Approximately one-fifth of Sweden's total emissions of carbon dioxide equivalents (CO2e) come from the construction sector. Energy usage in buildings has decreased over time, yet the CO2e emissions from the construction sector have remained unchanged. Even the building's installations have been overlooked despite the fact that they account for a significant proportion of the emissions linked to a building's life cycle. A life cycle analysis on a building can allow us to calculate and identify activities where emissions occur and prioritize areas that require further focus. The purpose of the study was to conduct a life cycle analysis of insulation materials in the building body and the installations in a new construction project; a preschool in Sundbyberg. A comparison was made between the CO2e emissions from insulation with various thicknesses and the CO2e emissions from the energy that is used during the building's lifetime. Three models of different insulation thicknesses were created, to compare the building's energy needs. For each model, different energy sources were used as a variable to identify the different impacts on a building’s CO2e-emissions. A theoretical future scenario was also created where the electricity and district heating sectors would move towards zero emissions by 2045. A different approach was taken for the installations, due to the lack of information in the area. A tool for the insulation of pipes and ducts was developed to be able to perform calculations on its CO2e-emission and compare it with the emissions of heat losses. Depending on the choice of energy source, the result varied, when less insulation was chosen, the emissions of the local energy sources benefited. However, in terms of Boverket's generic values, a cut-off point arose after 15 years where the choice of more insulation meant that the total CO2e-emissions decreased over a period of 60-years. For the future scenario, both cases showed that less isolation was the better option seen over the same period. The result is also affected by the limitations that the study has related to, for example, no consideration has been given to the secondary effects such as the extended floor structure, which becomes a natural effect of isolating more. In order to meet Sweden's climate goals of becoming climate neutral by 2045, emissions linked to the construction sector need to be reduced.
483

Study of Triply Periodic Minimal Surfaces for Heat Transfer Applications

Celaya Granados, María Xuan January 2023 (has links)
In the pursuit of enhancing heat exchanger efficiency, several heat transfer- enhancing strategies are employed. The traditional methods include surface vibrations, microchannels, and integration of vortex generators. Additionally, new solutions are being studied, taking advantage of other relevant improve- ments in the engineering field. The investigation of Triply Periodic Minimal Surfaces (TPMS) is one of the most recent and offers a passive and efficient approach to enhancing heat transfer performance.Triply Periodic Minimal Surfaces, characterised by their lattice structures, present an innovative opportunity for heat transfer applications. Notable TPMS configurations such as Schwarz Diamond, Schoen Gyroid, and Fischer Koch hold promise owing to their thermo-hydraulic characteristics. TPMS ex- hibits a high convection phenomenon due to its geometric attributes: great compactness (a large surface-area-to-volume ratio) and tortuosity, which pro- motes fluid mixing and turbulency. The representative periodic structures de- void of sharp edges of TPMS result in low hydrodynamic resistance and small pressure losses. Beyond their thermo-hydraulic attributes, TPMS are posi- tioned as robust candidates for high-pressure and high-temperature environ- ments. The integration of TPMS into heat exchangers offers substantial ad- vantages over traditional counterparts due to their enhanced heat transfer per- formance and reduced pressure drop.This study centres on the comparative analysis of two TPMS geometries, Fischer Koch S and Schwarz Diamond, to discern their performance in heat transfer applications. The study was conducted by simulating the two TPMS cells at different Reynolds numbers and analysing the obtained thermal and hydraulic results, which were performed using the Star-CCM+ Computational Fluid Dynamics software.The results show that for Reynolds numbers lower than 300, the Fischer Koch cell will outperform the Schwarz Diamond while maintaining compara- ble pressure drops. However, for higher Reynolds numbers, Schwarz Dia- mond performs better.
484

Low temperature catalytic hydrothermal treatment of biomass

Valfridsson, Patrik January 2017 (has links)
Advanced biofuel generation from biomass and waste via catalytic hydrothermal treatment and gasification
485

Techno-economic Analysis of Small Scale Solar Power Systems with Thermal Energy Storage in the Greek Market

Gerokostopoulou, Anna January 2019 (has links)
Climate change has been characterized as the greatest global health threat of the 21st century, therefore, measures in order to address this challenge need to be taken. The integration of renewables to power systems is key to decrease greenhouse gas emissions that negatively contribute to climate change. Furthermore, the coupling of renewable resources with energy storage, and especially long-duration energy storage, is an effective way to further increase renewable penetration to power systems overcoming the intermittency of such resources. Many countries have introduced support schemes for renewable based projects in order to attract investment and facilitate the deployment of renewables. Greece is among these counties having introduced attractive support schemes in order to decarbonize its energy mix which is still dependent extensively on fossil fuels. The aim of this work is to conduct a techno-economic analysis for three different small-scale solar-based energy projects in Greece, namely CSP, CSP with PV, and PV, all coupled with an innovative long-duration energy storage solution. Initially, the identification of existing support schemes is made through an analysis of the Greek electricity market, followed by the quantification of the potential market of solar-based projects in Greece. The study is focused on the Non-Interconnected Islands of Greece, since they present thegreatest potential for the decarbonization of the country’s energy mix. Through the techno-economic analysis the most suitable configuration for each project is identified, and thereafter, the three cases are compared against identified technical and financial Key Performance Indicators. The results of this work show that, with the current support schemes, a CSP project is the most profitable case, while a PV project coupled with long-duration energy storage provides the cheapest solution, presenting great potentials for the decarbonization of the Non-Interconnected Island in Greece. / Klimatförändringar har karakteriserats som det största globala hälsohotet under 2000-talet, därför måste åtgärder vidtas för att möta denna utmaning. Integreringen av förnybara energikällor i kraftsystem är nyckeln till att minska utsläppen av växthusgaser som negativt bidrar till klimatförändringen. Dessutom är kopplingen av förnybara resurser med energilagring, och särskilt långvarig energilagring, ett effektivt sätt att ytterligare öka förnybar penetration till kraftsystem som övervinner intermittensen av sådana resurser. Många länder har infört stödsystem för förnybara baserade projekt för att locka till sig investeringar och underlätta spridningen av förnybar energi. Grekland är bland dessa länder som har infört attraktiva stödsystem för att minska koldioxidutsläppen i sin energimix som fortfarande är mycket beroende av fossila bränslen. Syftet med detta arbete är att genomföra en tekno-ekonomisk analys för tre olika småskaliga solbaserade energiprojekt i Grekland, nämligen CSP, CSP med PV och PV, allt tillsammans med en innovativ lösning för långvarig energilagring. Inledningsvis görs identifieringen av befintliga stödsystem genom en analys av den grekiska elmarknaden, följt av en kvantifiering av den potentiella marknaden för solenergibaserade projekt i Grekland. Studien är fokuserad på Greklands icke sammankopplade öar, eftersom de har den största potentialen för avkarbonisering av landets energimix. Genom den tekno-ekonomiska analysen identifieras den mest lämpliga konfigurationen för varje projekt, och därefter jämförs de tre fallen mot identifierade tekniska och finansiella nyckeltal. Resultaten av detta arbete visar att med de nuvarande stödsystemen så är ett CSP projekt det mest lönsamma fallet, medan ett solcellsprojekt i kombination med långvarig energilagring ger den billigaste lösningen, vilket ger stora möjligheter för avkarboniseringen av den icke sammankopplade ön i Grekland.
486

Greywater recovery in buildings - Performance possibilities actors and strategies

Edström, Niklas January 2022 (has links)
Greywater includes domestic wastewater from sinks, showers, and laundry. Today, most of the greywater that leaves the building contains water and energy that could be re-circulated in the building. There is therefore a potential to recycle the greywater on property, which can lead reduction in water consumption at the building level. There are also gains to be made by recirculating the energy in the form of heat which is found in greywater. This thesis explores greywater recovery taking an actor perspective. When it comes to new water technologies, it is important to analyze the actors involved and their strategies. Both those who support it and those who oppose it. New technologies may produce benefits for some actors but can also be disruptive to other actors. Conflict can emerge between regulators (water laws, health and safety laws, etc) and technology developers. An actor analysis is performed for greywater recycling by a case study of the HSB Living Labs greywater project. HSB Living Lab is located in Gothenburg and has been studied as part of the project hosted at KTH titled “Ensuring sustainability and equality of water and energy systems during actor-driven disruptive innovation” (in short SEQWENS). The case study aims to map the different strategies of actors involved and affected by greywater recycling. Interviews with actors and a literature study are performed for the study. The projects shall be seen as a research experiment. The report concludes from the analysis that the price of water still is too cheap to make greywater recycling a priority for property owners. Further, the study shows that the regulation regarding warm water is not yet updated for on-property greywater technology to operate optimally. / Gråvatten (BDT-vatten) är avloppsvattnet från handfat, duschar och tvättstuga. Idag lämnar gråvattnet byggnaden med avloppssystemen. Det finns en potential att återvinna gråvattnet i fastigheter, vilket skulle minska byggnadens vattenförbrukning. Varje svensk förbrukar i genomsnitt 90 liter vatten som blir till gråvatten.När det kommer till ny teknik är det alltid nödvändigt att kartlägga de inblandade aktörerna och deras strategier. Både de som stöder teknikutvecklingen och de som är emot det. Ny teknik kan vara störande och vissa delar eller aktörer i systemet kan förlora sina positioner på marknaden. Återvinning av gråvatten är kanske inte nödvändigtvis ett acceptabelt alternativ för alla inblandade aktörer. Till viss del är återvinning av gråvatten inte nödvändigtvis ett acceptabelt alternativ för alla inblandade aktörer. Vissa aktörer kan vara för återanvändning av vatten (främst byggnadsägarna) medan andra kan vara misstroende. Andra typer av konflikter kan uppstå mellan tillsynsmyndigheter (vattenlagar, hälso- och säkerhetslagar etc) och teknikutvecklare. En aktörsanalys kommer att göras för återvinning av gråvatten genom en fallstudie av HSB Living Labs gråvattenprojekt. HSB Living Lab ligger i Göteborg. Fallstudien syftar till att kartlägga de olika strategierna för aktörer som är involverade och påverkade av gråvattenåtervinningen. Intervjuer med aktörer och enlitteraturstudie genomförs för studien. Rapporten drar slutsatsen från fallstudien att priset på vatten fortfarande är för billigt för att göra återvinning av gråvatten till en prioritet för fastighetsägare. Studien visar vidare att lagstiftningen kring varmvatten ännu inte är uppdaterad för att gråvattentekniken implementering i fastigheter ska fungera optimalt.
487

Energiteknisk utredning vid Boliden Rönnskär : Temperaturökning på svavelsyraverkets fjärrvärmeproduktion

Eriksson, Daniel January 2015 (has links)
Rönnskärverken is part of Boliden Mineral AB and is located on the coast outside of Skellefteå. Rönnskär receives raw materials from mines and electronic scrap to produce mainly copper, but also gold, silver, zinc and lead. In addition byproducts of sulfur dioxide and sulfuric acid are produced from the metal production. Besides this waste heat from processes is collected and produces steam and district heating. The steam is used to keeping boilers warm and in certain processes and production of district heating for local heating at Rönnskärsverken and consumers in Skelleftehamn and Ursviken. In the current situation waste heat from some processes is used and in addition to these, there are additional sources of heat that can be taken advantage of. Among these are the waste heat in a chimney connected to the sulfuric acid production and a cooler linked to the sea.This report deals with an investigation of the effect on Rönnskär’s steam- and district heating grid that a temperature increase on the produced district heating provides. The effects of two proposals on the utilization of the waste heat from a chimney tied to the sulfuric acid production and a proposal with the use of water vapor from the steam grid were investigated and compared economically.The investigation showed that one of the proposals, which uses waste heat from the chimney and a reduction in thermal cooling of heat with sea water, is of the examined proposals more advantageous from a financial perspective. This proposal corresponds to a saving of approximately 681 m3 oil of the type fuel oil 5 per year and is calculated to repay its investment cost within 6 months. / <p>Validerat; 20151113 (global_studentproject_submitter)</p>
488

Utredning av potentiella prosumenter anslutna till Härnösands fjärrvärmenät

Andersson, André January 2019 (has links)
No description available.
489

Novel cycles using carbon dioxide as working fluid : new ways to utilize energy from low-grade heat sources

Chen, Yang January 2006 (has links)
This licentiate thesis proposes and analyzes three carbon dioxide novel cycles, namely: the carbon dioxide transcritical power cycle, the carbon dioxide Brayton cycle and the carbon dioxide cooling and power combined cycle. Due to the different characteristics of each cycle, the three cycles are suitable for different applications. The CO2 transcritical power cycle is suitable for harvesting energy from low-grade heat sources, near which a low temperature heat sink is accessible. The CO2 Brayton cycle is suitable for harvesting the energy from relatively high-grade heat sources when there is no low temperature heat sink available. The CO2 cooling and power combined cycle is suitable for applications, where both power and cooling are needed (e.g. automobile applications, in which the cycle can utilize the energy in the engine exhaust gasses to produce power and provide cooling/heating to the mobile compartment room at the same time). Several models have been developed using the software known as Engineering Equation Solver (EES)1 for both cycle analysis and computer aided heat exchanger design. Different cycle working conditions have been simulated and different working parameters’ influence on the cycle performance has been explained. In addition, Refprop 7.02 is used for calculating the working fluid properties and the CFD tool Femlab has been employed to investigate the particular phenomena influencing the heat exchanger performance. / QC 20101124
490

Alternatives to carbon capture and storage (CCS) in the deep decarbonisation of the Norwegian cement industry : A cost-optimisation study of GHG mitigation measures

Vågerö, Oskar January 2020 (has links)
Norway’s two cement manufacturing plants are both among the top 10 largest national point sources of Greenhouse Gas (GHG) emissions and together contribute to 2% of the total GHG emissions. One of the important measures being pushed for to mitigate these emissions is Carbon Capture and Storage (CCS), for which the Norwegian Government is to make an investment decision in 2020/2021. Norway may end up with the first full-scale CCS project in the cement sector on a global basis, so the technology is still in its infancy in industrial applications outside of oil extraction. The aim of the study is to collate and summarise multiple data sources on the different measures that could mitigate greenhouse gases and which are feasible in a Norwegian context, in addition to CCS. The measures included are: energy effciency, fuel substitution, new types of clinkers, material effciency, clinker substitution, and substitution for wooden construction materials or biocement. The study utilises the concept of Marginal Abatement Cost (MAC) and Marginal Abatement Cost Curve (MACC) to assess and illustrate the environmental performance of the different measures versus a baseline scenario of 591 kg CO2e emitted per tonne cement manufactured. The two most promising measures are substituting part of the clinkers from the fnal cement product for a combination of calcined clays and ground limestone as well as increased use of fillers in concrete, which partially replace clinker in the final concrete product. These two measures are inexpensive and does not require any technology leap to implement. Barriers exist in the shape of a conservative construction industry where incremental innovation happen slowly. The industry is also utilising highly standardised product which make the entry of new and changed products diffcult and slow. No combination of measures achieve full decarbonisation of the cement industry, without including CCS, which indicates that it may still be necessary for the cement sector to become carbon neutral. / Se filen

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