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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.
51

Förbättrad biogaspotential med hydrokol som additiv : En laborativ studie om metanproduktion / Improved biogaspotential with hydrochar as an additive : A laboratory study on methane production

Kristoffersson, Maria January 2023 (has links)
Anaerob rötning är en naturlig nedbrytningsprocess av organiskt material som tar tillvara på avfall samtidigt som nyttig energi kan utvinnas. På Biogasbolaget AB i Karlskoga omvandlas substrat som matavfall, gödsel och ensilage till biogas som sedan kan uppgraderas till fordonsgas. Fordonsgasen kan användas som drivmedel till bussar i närområdet. Det bildas dessutom en rötrest som används som biogödsel, men som är kostsam för företaget. Rötkamrarna i Karlskoga är överdimensionerade i förhållande till den mängden substrat som levereras, vilket innebär att de kan ta hand om mer gas än det som bildas i dagsläget. Tidigare studier har visat att tillsats av hydrokol kan öka metangasproduktionen. Därför var syftet med studien att utvärdera ifall hydrokol kan öka metangasproduktionen i satsvis anaerob rötning. Målen var att jämföra två olika hydrokol; skogsindustriellt och kommunalt, samt att komma fram till en optimal dos. Eftersom området är relativt nytt var det också av intresse att ta reda på hur klimatpåverkan förändras vid tillsats av hydrokol genom att utföra en enkel livscykelanalys.   Utvärderingen av hydrokolets potential i anaerob rötning utfördes genom satsvis rötning i två omgångar. Substrat och ymp hämtades från Karlskogas biogasanläggning. De doserna hydrokol som testades i båda försöken var 4, 8 och 10 g/l samt referensfallet 0 g/l vilket motsvarade Karlskogas förhållanden. Det gjordes även försök med endast hydrokol för att ta reda på om det var hydrokolet i sig som producerade metangas. Den satsvisa rötningen visade att det kommunala hydrokolet med en dos på 8 g/l gav mest metangas (841 Nml/g VS) jämfört med referensen 0 g/l (435 Nml/g VS) vilket var en ökning med 93%. Det skogsindustriella hydrokolet med en dos på 8 g/l visade en ökning med 16,6% (517 Nml/g VS) jämfört med referensen 0 g/l (443 Nml/g VS). Den enkla livscykelanalysen visade att det resulterade i en större minskning av utsläpp när dieselbussar kan bytas ut mot hydrokolsbaserad biogas jämfört med vanlig biogas. Vid tillsats av kommunalt hydrokol till biogasprocessen blev besparingen 14783 ton CO2.ekv./år vid utbyte av diesel och för skogsindustriellt hydrokol motsvarade besparingen 8938 ton CO2.ekv./år. Det jämfört med biogas som produceras utan hydrokol som vid utbyte av diesel sparar 7688 ton CO2.ekv./år. Massflödesanalysen visade att det teoretiskt är möjligt att använda Karlskogas rötrest för att använda som substrat till HTC-anläggningen och därmed införa ett cirkulärt system. Däremot visade metallanalysen att det finns risk för förhöjda mängder tungmetall i rötresten, vilket skulle kunna leda till att de inte klarar de krav som finns för att certifiera biogödseln.   För Biogasbolaget AB i Karlskoga innebär resultaten att de med 8 g/l kommunalt alternativt skogsindustriellt hydrokol skulle kunna öka sin metangasproduktion med 93% respektive 16,6%. Däremot kan det leda till problem med metallhalterna i rötresten som riskerar att överstiga gränsvärdena som finns för biogödsel. / Anaerobic digestion is a natural decomposition process of organic material that utilizes waste while extracting useful energy. At Biogasbolaget AB in Karlskoga, substrates such as food waste, manure, and silage are converted into biogas, which can then be upgraded to vehicle fuel. The vehicle gas can be used as fuel for buses in the local area. Additionally, a digestate is formed, which is used as biofertilizer but is costly for the company. The digesters in Karlskoga are oversized compared to the amount of substrate delivered, which means they can handle more gas than is currently being produced. Previous studies have shown that the addition of hydrochar can increase methane gas production. Therefore, the aim of the study was to evaluate whether hydrochar can increase methane gas production in batch anaerobic digestion. The goals were to compare two different types of hydrochar: from the forestry industry and municipal sources, and to determine the optimal dosage. Since the area is relatively new, it was also of interest to determine how the climate impact changes with the addition of hydrochar by conducting a simple life cycle analysis.   The evaluation of hydrochar's potential in anaerobic digestion was carried out through batch digestion in two rounds. Substrate and inoculum were obtained from Karlskoga's biogas plant. The doses of hydrochar tested in both experiments were 4, 8, and 10 g/l, as well as the reference case of 0 g/l, which corresponded to Karlskoga's conditions. Experiments were also conducted with hydrochar alone to determine if it was the hydrochar itself that produced methane gas. The batch digestion showed that the municipal hydrochar with a dosage of 8 g/l produced the most methane gas (841 Nml/g VS) compared to the reference of 0 g/l (435 Nml/g VS), which was an increase of 93%. The forestry industry hydrochar with a dosage of 8 g/l showed an increase of 16,6% (517 Nml/g VS) compared to the reference of 0 g/l (443 Nml/g VS). The simple life cycle analysis showed that it resulted in a greater reduction in emissions when diesel buses can be replaced by hydrochar-based biogas compared to regular biogas. When municipal hydrochar was added to the biogas process, the savings amounted to 14,783 tons of CO2 equivalent per year through diesel substitution. For forest industry hydrochar the equivalent resulted in savings of 8,938 tons of CO2 equivalent per year. This is in comparison to biogas produced without hydrochar, which saves 7,688 tons of CO2 equivalent per year when substituting diesel. The mass flow analysis showed that it is theoretically possible to use Karlskoga's digestate as substrate for the HTC plant, thus introducing a circular system. However, the metal analysis revealed a potential risk of elevated levels of heavy metals in the digestate, which could prevent it from meeting the requirements for certifying the biofertilizer.   For Biogasbolaget AB in Karlskoga, the results mean that with 8 g/l of municipal or forest industry hydrochar, they could increase their methane gas production by 93% and 16.6%, respectively. However, this could lead to issues with metal levels in the digestate, which may exceed the threshold values set for  biofertilizer.
52

Utveckling av ett flytande montagesystem för solpaneler / Development of a floating solar mounting system

Säther, Vilma January 2022 (has links)
Framtidens energimix kommer till stor del innebära användning av förnyelsebara energikällor, så som solen. Solens energi strålar konstant in på jorden och den är tillgänlig att använda så länge den kan omvandlas på rätt sätt. Solpaneler används numera för att omvandla solens energi till elektricitet.  Panelerna monteras vanligen på markställning men skulle med fördel även kunna monteras på ställningar som flyter på vatten. Med uppdrag av E.ON ska detta arbete undersöka möjligheten och presentera ett konceptförslag för ett flytande montagesystem. Montagesystemet som presenteras i projektet är ett teoretiskt framtaget system som framförallt fokuserar på funktionen. Resulatet är även till viss del baserat frågeställningar ur hållbarhetssynpunkt och även ur tillverkningssynpunkt. Arbetet präglas till stor del av produktutvecklingsprocessen men med inslag av maskinteknik för att ett funktionsdugligt koncept ska stå i fokus. Avslutningsvis diskuteras bland annat möjligheter till vidareutveckling, alternativa lösningsförslag och vindlastens påverkan. Det slutgiltiga konceptförslaget är ett avstamp i en framtida vision om en grönare energiframställning och i längden en förändrad värld. / The use of renewable energy sources, for example solar energy, will be a big part of the energy mix in the future. The sun constantly radiates its energy onto earth and with the right kind of conversion technology it is available for us to use. The progress of developing solar panels have made this possible. The panels are usually installed on a ground mounted rack but there would be several advantages with placing the panels on top of a floating mounting system. On behalf of E.ON, the assignment is to analyze the possibilities with having floating solar panels and with that in mind develop a suggestion for a functioning floating solar mounting system. The concept that is being introduced in this project is a theoretical outcome that primarily focus on functionality. The result is also based on questions regarding sustainability and manufacturing. The project itself is mostly characterized by the product development process, but does also include subjects such as mechanical engineering since the aim with the given assignment is to present a concept based on its functionality. With the final suggestion in mind, the discussion is primarily based on further development possibilities, alternative solutions and the influence of the wind load. This is hopefully the beginning of a new, greener chapter in the making of energy and the possibility of changing the world.
53

Business Models for Energy Communities : A Case Study on the Swedish Market / Affärsmodeller för Energisamhällen : En Fallstudie av den Svenska Marknaden

Hartmanis, Eric, Lindblom, Robin January 2021 (has links)
Global warming is one of our time’s most pressing issues and the energy industry is the leading cause. In the current Swedish electricity systems, individual consumers hold little to no power as the system is inherently centralized, with large incumbent actors. The Swedish electricity grid is prognosticated to encounter a troublesome situation with grid capacity as society enjoys and evergrowing electrification. The climate issueshave however given renewable energy a more predominant role in the Swedish energy sector. Through the directives of the European Union’s Clean Energy Package, each member state now has to enact laws enabling for individuals to cooperatively engage in selfproduction of energy as a joint entity, which in turn enables for new niche technologies to become market actors. Energy communities is such an entity with a promising outlook to become both a considerable market actor, and an actor that can help alleviate grid tensions. The purpose of this study is to: 1) investigate how the internal business model for energy communities could be constructed in order to maximize societal outreach and promote the creation of new energy communities, and 2) to investigate how the business models could be constructed in order to coexist with the incumbent structures, while contributing to the developments in the sociotechnical regime. The study utilizes an abductive approach through the form of a single case study and qualitative data collection methods. The results are presented and analyzed using the business model canvas framework and its potential is analyzed through the MultiLevel Perspective. The prospects of energy communities in Sweden using photovoltaic (PV) production units are overall positive. The value propositions that lie at the core of the proposed business model are constituted of environmental benefits, autarky, social values and economic costs savings. The most prosperous developmental path for energy communities in order to in the future be recognized in the sociotechnical regime is through a relationship characterized by cooperation with the incumbent structures. / Global uppvärming är en av vår tids största problem, och energiindustrin är den största bidgrande faktorn. I det nuvarande energisystemet har individen lite kontroll, eftersom systemet är till hög grad centraliserat med stora aktörer. Effektbrist och kapacitetsbrist är växande problem i det svenska elnätet, vilket späds på av ökad elektrifiering. Klimatförändringarna har dock givits en större roll i den svenska energisektorn. Genom ett direktiv på EU nivå, Ren Energi paketet, kan nu varje medlemsstat etablera lagar för hur individer kan engagera sig och samarbeta i elproduktion för att själva bli marknadsaktörer. Ett samlingsnamn för sådana aktörer är energigemenskaper. Energigemenskaper kan bidra till att motverka både klimatkrisen men också problemen i elnäten. Syftet med denna studie är att: 1) undersöka hur affärsmodellen för energigemenskaper kan utformas så att man maximerar samhällsspridning och promoterar skapandet av nya energisamhällen, och 2) undersöka hur affärsmodellen can konstrueras så att de kan samexistera med nuvarande aktörer i energisystemet och dessutom utveckla det vidare. Denna studie har ett abduktivt tillvägagångssätt, genom en fallstudie med kvalitativ datainsamling. Resultaten presenteras och analyseras med business model canvas och dess potential undersöks med hjälp av MultiLevel Perspective ramverket. Utsikterna för energigemenskaperna, med fokus på solcellsproduktion, är överlag goda. Energigemenskapens affärsmodells främsta värderbjudanden var klimatmedvetenhet, autarki, sociala attribut och kostnadsbesparingar. Den mest lovande utvecklingsbanan för energigemenskaper inkluderar karaktäriseras av inkludering och samarbeta med de stora och nuvarande aktörerna i energisystemet.
54

Optimering av driftstemperatur vid mesofil rötning av slam : - funktionskontroll vid Uppsalas reningsverk / Optimizing operational temperature in mesophilic digestion of sewage sludge : – a study at Uppsala wastewater treatment plant

Andersson, Johanna January 2019 (has links)
För att minska klimatpåverkan är energisnåla processer och användning av fossilfria bränslen viktigt. Vid stabilisering av avloppsslam vid reningsverk är en vanlig metod rötning som förutom att ta hand om slammet även producerar biogas, ett fossilfritt bränsle med låga växthusgasutsläpp. Processer som drivs inom det mesofila temperaturområdet har visat sig vara stabila och ger en jämn gasproduktion. Det mesofila området sträcker sig mellan 25–40°C men de flesta processer drivs mellan 35–40°C. Den här studien undersöker möjligheten att sänka temperaturen inom det mesofila området för att få en lägre energiförbrukning och en energisnålare process. Då det är viktigt att biogasproduktionen inte försämras av en sänkt temperatur har skillnad i utrötningsgrad, metanpotential och utrötningstid undersökts vid tre olika temperaturer (32, 34,5 samt 37,5°C) via satsvisa utrötningsförsök. Utöver påverkan på biogasproduktionen har en energibalansberäkning utförts för rötkamrarna vid Uppsala reningsverk. Detta ger ett mått på hur stora vinster i värmeenergi en sänkt temperatur kan leda till. En betydande kostnad vid reningsverk är avvattningen av slam och det är därför viktigt att den inte riskerar att försämras om temperaturen sänks. Ett filtreringsförsök som mäter CST (Capillary Suction Time) ger ett mått på slammets avvattningsegenskaper och har därför utförts vid tre olika temperaturer. Resultaten visade ingen försämring i biogasproduktion vid en sänkning till 34,5°C och en minskning i metanpotential med 11 % vid en sänkning till 32°C. Nedbrytningshastigheten försämrades inte vid en sänkt temperatur. Vinster i form av lägre värmeförbrukning uppgick till 14 % vid sänkning till 34,5°C och 27 % vid sänkning till 32°C. Avvattningsförsöket visade ingen försämrad avvattning vid lägre temperaturer. Den här studien visar att det finns en möjlighet att sänka temperaturen i rötkammaren vid reningsverket i Uppsala och på så sätt sänka energiförbrukningen. För att bekräfta resultaten bör även kontinuerliga försök utföras men denna studie visar att det är möjligt att få en lyckad nedbrytning även i lägre mesofila temperaturer. Resultatet öppnar upp för fortsatta undersökningar om temperaturförändringar inom det mesofila området och kan leda till en optimering av rötningsprocessen och möjlighet att få en effektiv och energisnål produktion av biogas. / Energy efficient processes and the use of fossil free fuels play an important role in order to reduce the impact of climate change. Anaerobic digestion is a common way for stabilizing sewage sludge at wastewater treatment plants (WWTP). One of the benefits with anaerobic digestion is that it also produces biogas, a fossil free fuel with low greenhouse gas emissions. An operational temperature within the mesophilic range has proven to give a stable process with an unfluctuating production of gas. The mesophilic temperature range between 25-40°C but most processes are operated between 35-40°C. This study investigates the opportunity to lower the temperature within the mesophilic range in order to reduce energy consumption. It is important to maintain the production of biogas with a lower temperature. Therefore, the reduction in VS-content (VS-volatile solids), methane yield and time for degradation was determined by a BMP-experiment (BMP-Biochemical Methane Potential) in three different temperatures (32, 34.5 and 37.5°C). In order to quantify the reduction in heat consumption with lower operational temperatures the change in heat balance for a full-scale WWTP in Uppsala was calculated. A major part of the operational cost is dewatering of sludge and it is therefore important that it does not deteriorate with a lower temperature. The effect on the dewaterability at different temperatures was examined by a filterability test measuring CST (capillary suction time). The results from the study showed no significant difference in methane yield between 37.5°C and 34.5°C. The methane yield at 32°C was 11 % lower compared to 37.5°C but the degradation kinetic was not affected by a temperature change. The reduction in heat consumption was 14 % when the temperature was reduced to 34.5°C and 27 % when it was reduced to 32°C. The filterability test did not show a deterioration with lower temperatures. The study showed that it is possible to reduce the operational temperature for anaerobic digestion at the WWTP in Uppsala in order to reduce the energy consumption. To confirm these results a continuously experiment should be done, but this study shows that it is possible to get a successful degradation in a lower mesophilic temperature. This leads the way for further investigations within the mesophilic range and could lead to optimizing anaerobic digestion and the opportunity to get an energy efficient production of biogas.
55

Femmilsradie : Hållbar möbelproduktion / Within a range of fifty kilometers : A strategy for sustainable furniture production

Erik, Lith, Lundin, Hannes January 2012 (has links)
Hållbarhet handlar om att främja välfärd nu, och i all tid framöver, genom att ta hänsyn till egologiska, sociala och ekonomiska aspekter. Det handlar om att tillgodose dagens behov utan att förstöra möjligheterna för kommande generationer att tillgodose sina. Vårt examensarbete undersöker förutsättningarna för hållbar möbelproduktion. och vi gör detta genom ett flödesschema som skall användas vid uppstart av hållbart producerande företag. Idén bygger på att råvarorna utvinns och förädlas inom en femmilsradie. Vi hoppas kunna åstadkomma en djupare relation mellan användaren och objektet än vad endast köpande och ägande ger. Vi har valt att tydliggöra konstruktion och uppbyggnad, samtidigt som formen uppmanar förnuftet till kritiskt ifrågasättande av stabilitet och hållbarhet både konkret och i ett vidareperspektiv. Vi vill att objektet skall kunna utvecklas, individualiseras och anpassas efter användaren så att de tillsammans kan leva vidare in i ett samhälle vi ännu inte känner till. / Sustainability is about promoting prosperity now, and in the future, by taking into account ecological, social and economic factors. It is about meeting the demands of today without compromising the ability of future generations to meet theirs. Our thesis explores the conditions for sustainable furniture production through a flowchart, intended for use at the startup of sustainable manufacturing companies. The concept is based on the idea of raw materials being extracted and processed within a fifty kilometre radius. We hope to bring about a deeper relationship between user and object than that which comes with mere purchasing and ownership. We have chosen to make construction and structure apparent, while the design invites the mind to critical questioning of stability and sustainability, both in a literal and a wider sense. We want the object to be developed, personalised and tailored to the user, so that together they can live on in a society that we do not yet know
56

Optical active thin films on cover glass increasing the efficiency of photovoltaic modules.

Johansson, Wilhelm January 2018 (has links)
Thin film coatings of ZnO, TiO2, CeOX and BiOX have been deposited on soda lime silica glass through spray pyrolysis. The effects on the optical properties of the coated glass, as well as the possible impacts on the life expectancy and energy efficiency of PV-modules have been studied. ZnO and TiO2 coatings both reduced the transmission of UV radiation of wavelengths destructive to PV-modules. Therefore, both have the potential to increase the life expectancy of PV-modules if used on cover glass. The ZnO thin film also showed an increase in photoluminescence at 377 nm when radiated with UV radiation of 325 nm while TiO2 reduced the photoluminescence. ZnO coatings on the cover glass have the potential to increase the efficiency of PV-modules in addition to UV protection. No CeOX or BiOX films were found to be deposited with the method used. The ZnO and TiO2 coated samples showed a decrease in transmission of light, due to increased reflection and possibly scattering. This needs to be addressed if these kinds of coatings are going to be beneficial for Si PV-modules.
57

Increasing the profitability of a PV-battery system : A techno-economic study of PV-battery systems as resources for primary frequency regulation

Samuel, Forsberg January 2018 (has links)
In order to handle the mismatch between photovoltaic (PV) electricity production and household electricity use, battery storage systems can be utilized. However, the profitability of PV-battery systems in Sweden is poor, and economic incentives for households to invest in such systems are therefore missing. Hence, it is important to improve the profitability to increase the number of PV-battery installations. The aim of this thesis is to investigate the techno-economic potential of a PV-battery system offering ancillary services, more specifically the primary frequency regulation FCR-N. Five cases of residential PV-battery installations are investigated: the first with a PV system only, the second with a PV-battery system to store surplus PV electricity, and the three other cases with PV-battery systems with the ability to regulate the grid through FCR-N to varying degrees. The results show that providing FCR-N with a PV-battery system offers a substantial techno-economic potential for the system owner. By using available battery capacity for FCR-N, the payback time for a PV-battery system can be shortened significantly. With a battery price of EUR 570 per kWh (VAT excluded) and a discount rate of 2%, the payback time for the entire system can decrease from 32 to 9 years if the battery is used for FCR-N regulation. Furthermore, the payback time for a battery storage can be shortened with FCR-N. Calculated with respect to the economic added value of a battery and with a discount rate of 5%, the payback time can decrease from over 100 years to 4 years.
58

Hästavmaskningsmedels påverkan på miljö och välfärd

Landgren, Emilia, Wallman, Sabina January 2014 (has links)
Healthy, natural pastures is very valuable for biodiversity in the form of both plants and animals. An efficient use of pastures helps to preserve biodiversity, but grazing animals needs to be de-wormed to keep them healthy and to prevent harmful parasites spread on the pasture. The awareness about the environmental impact of the frequent use of deworming agents is low among the public. Some people are unaware that the absorption in horses of anthelmintics is incomplete, which make the circumstances about enviromental effect important to investigate further. The scientific evidence in this area is limited and more studies and trials are needed to deepen the knowledge about the effects of anthelmintics in the environment. Our report includes a compilation of studies conducted on anthelmintics and equine parasites, as well as an experiment which was conducted at the University of Halmstad biogaslaboratory April 2014. Anthelmintics have been shown to have negative impact on the manure ecosystem and especially against manure living fauna. Deworming routines has changed over the years as the equine industry has developed. Nevertheless, there’s still a lack of concrete approach to deworming.
59

Gårdsbaserad biogas på Nya Skottorp : utvärdering och optimering av anläggningen och uppgradering av biogasen

Kalén, Jonas, Åkerlund, Nathan January 2013 (has links)
Biogas is an expanding sector within the broad field of agriculture and animal production. Small-scale biogas offers local combined power and heating production and the substrate is transformed into high-quality biological fertilizer. This bachelor thesis focuses on a pig farm in south-western Sweden, where biogas is produced from pig manure, evaluates and suggests ways of optimizing the process and investigates whether investing in an upgrading plant would be a feasible and more cost-efficient option. The results show that the biogas plant is working well, although the production differs from the original plans. This shows in turn that planning and examining the basic conditions before making the investment is of great importance, as well as monitoring and keeping detailed statistics of the running process. Logistical factors make optimizing the process through additional substrates difficult. The thesis shows that investing in a Biosling upgrading plant would be a profitable option, supposing that the upgraded gas is sold via the natural gas infrastructure. Furthermore, many farmers are interested in producing their own fuel for tractors and other machines, which offers more future alternatives for the upgraded biogas. However, biogas producers in Sweden today are not offered any particular subsidies, which makes it especially hard for small-scale producers.
60

A market-based instrument for renewable energy : Modelling a dynamic price function for local areas

Flygare, Carl January 2019 (has links)
This thesis describes the current situation of the electrical grid on a general level and contemporary support policies for residents who feed renewably produced electricity into the grid within a Swedish context. It shows which issues currently exists and suggests a new way to value overproduced renewable electricity which is not self-consumed. This way is called a dynamic price function (DPF), and this thesis models, simulates and analyzes the DPF in order to create an economic incentive to support the balance of the electrical grid – one of its most important parameters. The suggested DPF could potentially work with any renewable source in any area, but the focus in this thesis has been on solar power-systems for households in local areas. While the currently support policies, which uses static models to value overproduced renewable electricity, have created important incentives for the initial penetration of solar power among local residents they do not scale well as the share of renewable production on a local level increase. This might cause negative impacts on the electrical grid. The thesis’ results show that by designing the DPF in certain ways it is possible to create an economic incentive for different behaviors. The most promising design incorporates three different incentives at the same time and they are: 1) to incentivize the initial penetration of solar power in local areas which do not have any production, 2) to incentivize a higher share of solar power, but not too high, and 3) to procure storage possibilities for overproduced electricity. These incentives do not only encourage a more even geographical distribution of solar power, but also allow for a higher share of solar power in the energy system without risking the balance of the grid.

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