<p>In this research, liquid-liquid dispersion of viscous fluids was studied in an SMX static mixer in the laminar regime. Backlighting technique was used for flow visualization, and the Hough transform for circle detection was used in OpenCV to automatically detect and measure drop diameters for obtaining the size distribution. Silicone oil and an aqueous solution of high fructose corn syrup were used for dispersed and continuous phases respectively, and sodium dodecyl sulfate was used as the surfactant to modify the interfacial tension. Experiments were conducted at varying viscosity ratios and flow rates-each at zero, low (~200 ppm) and high (~1000 ppm) surfactant concentrations. The effect of holdup was explored only for a few cases, but it was found to have a minimal effect on the weighted average diameter D₄₃.</p> <p>It was found that the superficial velocity and the continuous phase viscosity had a dominant effect on D₄₃. The tail at the higher end of the droplet size distribution decreased with increasing superficial velocity and continuous phase viscosities. It was also found that D₄₃ decreased with lowering of the interfacial tension. Furthermore, the effect of the dispersed phase viscosity was significant only at non zero surfactant concentrations.</p> <p>An approximate model has been proposed that relates D₄₃ to the capillary number. It is based on an energy analysis of the work done by the viscous and surface forces on a drop of an initial diameter that is largely determined by the gap distance between the cross bars in the element</p> / Master of Applied Science (MASc)

<p>Microdroplets have large and varied areas of application ranging from document printing to complex lab-on-chip devices. Lab-on-chip systems often require precise volume control as well as high throughput operations. Microdroplets fulfill these requirements and have become a staple in these devices. The work presented in this thesis involves the design and characterization of two individual devices capable of droplet generation utilizing flow focusing and electrogeneration methods.</p> <p>The first design involved the generation of gel microdroplets utilizing the flow focusing technique. This device proved to be robust and reliable producing large volumes of uniformly mixed droplets. Long term operation of this device was analyzed and determined to be a feasible route for the manufacture of large quantities of droplets. The device was operated for over 30 hours creating gel droplets ranging from 40-200 μm in diameter with acceptable polydispersities for use in drug release studies.</p> <p>The second device involved the design and characterization of a system for the electrogeneration of microdroplets. This novel device involved the injection of droplets via high voltage and high frequency signals into a cross-flow of oil. The droplet generation was characterized and different droplet generation modes were observed. With the careful selection of parameters ideal conditions were obtained to generate monodisperse droplets of sizes ranging from under 5 to over 100 μm in a highly repeatable manner.</p> <p>To conclude, two separate microfluidic droplet generation devices operating in distinct modes were designed and analyzed. These devices are robust, reliable, and flexible with some applications being tested.</p> / Master of Applied Science (MASc)

<p>Injectable, in-situ gelling magnetic plum pudding hydrogel composites were fabricated by entrapping superparamagnetic iron oxide nanoparticles (SPIONs) and thermosensitive N-isopropylacrylamide (NIPAM)-co–N-isopropylmethacrylamide (NIPMAM) microgels in a pNIPAM-hydrazide/carbohydrate-aldehyde hydrogel matrix. The resulting composites exhibited significant, repeatable pulsatile release of 4 kDa FITC-dextran upon exposure to an alternating magnetic field. The pulsatile release from the composites could be controlled by altering the volume phase transition temperatures of the microgel particles (with VPTTs over 37°C corresponding to improved pulsatile release) and changing the microgel content of the composite (with higher microgel content corresponding to higher pulsatile release). By changing the ratio of dextran-aldehyde (which deswells at physiological temperature) to CMC-aldehyde (which swells at physiological temperature) in the composites, bulk hydrogel swelling and thus pulsatile release could be controlled; specifically, lower CMC-aldehyde contents resulted in little to no composite swelling, improving pulsatile release. <em>In vitro</em> cytotoxicity testing demonstrated that the composite precursors exhibit little to no cytotoxicity up to a concentration of 2000 µg/mL. Together, these results suggest that this injectable hydrogel-microgel composite hydrogel may be a viable vehicle for <em>in vivo</em>, pulsatile drug delivery.<strong></strong></p> / Master of Applied Science (MASc)

The objectives of the thesis were to find the mechanisms that govern compression failures in paperboard and to find the link between manufacturing process and paperboard properties. The thesis also investigates two different test methods and evaluates how suitable they are for paperboard grades. The materials are several commercial board grades and a set of hand-formed dynamic sheets that are made to mimic the construction of commercial paperboard. The method consists of mounting a stereomicroscope on a short-span compression tester and recording the compression failure on video, long-span compression testing and standard properties testing. The observed failure modes of paperboard under compression were classified into four categories depending on the appearance of the failures. Initiation of failure takes place where the structure is weakest and fiber buckling happens after the initiation, which consists of breaking of fiber-fiber bonds or fiber wall delamination. The compression strength is correlated to density and operations and raw materials that increase the density also increases the compression strength. Short-span compression and Long-span compression are not suitable for testing all kinds of papers; the clamps in short-span give bulky specimens an initial geometrical shape that can affect the given value of compression strength. Long-span compression is only suitable for a limited range of papers, one problem with too thin papers are low wavelength buckling.

I Sverige har målet länge varit att reducera mängden växthusgasutsläpp från transportsektorn [1]. Ambitionen har därför varit att försöka fasa ut användningen av fossila bränslen som till exempel diesel. Det har bland annat gjorts genom att öka andelen elbilar och skapa förutsättningar för det genom att etablera en storskalig infrastruktur för laddningsstationer runtom i landet. På senare tid har intresset för vätgas som ett potentiellt drivmedel för fordon ökat markant. Detta har i sin tur motiverat olika aktörer (industri, akademi, transportsektor och offentliga sektor) i Mellansverige att ingå i ett partnerskap för att tillsammans vidareutveckla detta mål genom att initiera samverkansprojektet ”Mid Sweden Hydrogen Valley”. Projektets ambition är att utforma och driva storskalig vätgasproduktion i syfte att bland annat stegvis introducera vätgasdrivna transportmedel i Gävle hamn som ett alternativ till nuvarande dieseldrivna fordon i hamnen. Detta då vätgasdrivna fordon erbjuder grön transport, längre körsträcka, snabbare påfyllningstid samt en viktmässigt lättare bränslelager jämfört med tunga batterier i elbilar. För att uppnå detta måste först vätgasinfrastruktur etableras för att skapa en tillgänglighet och därför har Mellansverige som huvudmål att ta en ledande roll.  Detta masterprojekt hade som mål att utforma och undersöka om en storskalig vätgasproduktionsanläggning som drevs på förnybar energi (vindkraft), hade potentialen att bli ekonomiskt lönsamt utifrån ett investeringskalkylsperspektiv. Detta gjordes genom att först konstruera en generell och optimerad konfiguration av en sådan anläggning. Detta tillvägagångssätt involverade bland annat att ta reda på vilka relevanta komponenter som behövdes, analysera lämpliga teknologier och undersöka komponenternas kommersiella tillgänglighet. En tekno-ekonomiskt analys tillämpades därefter på den färdigställda anläggningen. Den tekno-ekonomiska analysen genomfördes i form av en fallstudie för åren 2019, 2020 och 2021, där en fiktiv vätgasanläggning i Gävle hamn anslöts till en fiktiv havsbaserad vindkraftspark strax utanför hamnen. Denna havsbaserade vindkraft var i samma stund ansluten till nätet via en närliggande anslutningspunkt. Syftet var att ta reda på vid vilka spotpriser som funktion av vätgaspris, där det var lönsamt att producera vätgas i stället för att sälja elektriciteten direkt till elmarknaden. Dessa spotpriser räknades fram genom att subtrahera alternativintäkten av att sälja elen till nätet från vätgasens försäljningspris. Dessa spotpriser användes till att erhålla antalet lönsamma produktionstimmar av vätgas. Baserat på dessa lönsamma produktionstimmar kunde den totala generade inkomsten av vätgasförsäljning kalkyleras. Den slutliga vinsten beräknades genom avdrag av anläggningens fasta kostnader från den genererade rörliga inkomsten. Denna fallstudie är baserad på en djupgående litteraturstudie samt kontakt med Svenska Kraftnät (SvK), Energimyndigheten, diverse vindkraftsproducenter och Svea Vind Offshore. Tre varianter av fallstudien skapades där den enda skillnaden var storlekarna på huvudkomponenterna PEM elektrolys, kompressor, lager och vätgastankstation. I denna rapport valdes följande tre elektrolyskapaciteter: 5 MW, 10 MW och 20 MW.  Resterande komponenter dimensionerades utifrån elektrolysens kapacitet. Anledningen till att tre olika anläggningsvarianter studerades var för att ta reda på om det fanns ett tydligt samband mellan anläggningens storlek och sannolikheten att uppnå ekonomisk lönsamhet. Resultaten visade att dessa tre anläggningsstorlekar bar på olika för- och nackdelar. Fördelen som en 5 MW anläggning hade var till exempel flest antal produktionstimmar men nackdelen att den producerade minst mängd av vätgas. En 20 MW anläggning hade minst antal produktionstimmar men störst vätgasproduktion vilket resulterade i höga vinster. Enligt vad som kan förväntas låg 10 MW-anläggningen mellan 5 MW och 20 MW när det kom till antalet produktionstimmar och genererad vinst. Denna information var dock inte tillräcklig för att utfärda en slutlig bedömning gällande vilken anläggning som hade störst potential att uppnå lönsamhet. Detta grundade sig i att alla dessa anläggningsvarianter var enkelt konstruerade, vilket innebar att många mindre komponenter som också har en teknisk och ekonomisk inverkan, inte togs med i beräkningarna. Utöver detta så antogs även att anläggningen arbetade helt isolerat, vilket innebar att inget vätgasläckage ägde rum, något som inte överensstämmer i praktiken. / The goal to reduce emissions of greenhouse gases from the transportation sector in Sweden, has been ongoing for a while [1]. Therefore, the ambition to phase out the usage of fossil fuels such as diesel, has been actively taking place through different strategies. One such strategy is to increase the share of electric cars and apply a major effort in establishing a large-scaled infrastructure for charging stations throughout the country. Recently, interest in hydrogen as a potential fuel has significantly increased. This has in turn motivated different actors (industry, academia, transport, and public sector) in mid Sweden to form a partnership to further develop this goal by initiating a collaborative project called "Mid Sweden Hydrogen Valley”. The project’s ambition is to construct and operate a large-scale hydrogen production facility with the aim of, among other things, gradually introducing hydrogen fueled vehicles in Gävle harbor. The hydrogen fueled vehicles will pose as alternatives to current operating diesel fueled vehicles in the harbor. The plausible reasons for hydrogen fuel in the transport sector is that it offers green transport, longer driving distances, faster refueling time, and a lightweight fuel storage compared to the heavy batteries in electric cars. To achieve this, hydrogen infrastructure must first be established to create accessibility. Thus, the collaboration in mid Sweden has the mission of taking a leading role in this matter.  The aim of this master thesis is to investigate whether a large-scale hydrogen production facility powered by renewable energy (wind energy) has the potential of becoming economic viable from the perspective of an investment calculation. This investigation was executed by firstly constructing a generalized and optimized configuration of such a facility, which, in turn, was accomplished by analyzing what type of relevant equipment that was needed, studying, and selecting appropriate technologies, and examining the commercial availability of the equipment. Thereafter, a techno-economic analysis on the facility’s operational process was applied. This analysis was conducted in the form of a case study for the following target years 2019, 2020 and 2021, where a hydrogen production plant was placed in Gävle harbor and was connected to a hypothetical offshore wind farm, situated just outside the harbor. This offshore wind farm was simultaneously connected to the grid via a nearby connection point. The purpose was to determine which spot prices, as a function of different hydrogen prices, made it possible to produce and sell hydrogen at a profit rather than selling the electricity directly to the grid. These breakeven spot prices were computed by subtracting the alternative revenue of selling electricity to the grid from the selling price of hydrogen. Thereafter, these spot prices were used to obtain the profitable number of hydrogen production hours. Based on these hydrogen production hours, the total variable income generated from selling hydrogen could be calculated. Finally, the actual profit was calculated by deducting the facility's fixed costs from the generated income. This case study was based on an in-depth literature research and contact with Svenska Kraftnät (SvK), the Swedish Energy Agency, different wind power producers, and Svea Vind Offshore. Three variants of the case study were produced, where the only difference were the sizes of the main components: PEM electrolysis, compressor, storage, and hydrogen refueling station. In this report, the following three electrolyzer capacities 5 MW, 10 MW, and 20 MW, were selected. The dimensions of the other components were based on the electrolyzer’s capacity. The reason for producing three different facility sizes, was to determine whether there was a correlation between facility size and the probability of achieving economic profitability. The results showed that these three facilities possessed different advantages and drawbacks. The 5 MW facility had the advantage of obtaining the highest number of productions hours but had the drawback of generating the least volume of hydrogen. However, the 20 MW facility had the fewest production hours but the highest volume of hydrogen production, resulting in high profits. Lastly, the 10 MW facility fell between the 5 MW and 20 MW in terms of the number of production hours and generated profit. However, this information was not sufficient to make a final deciding of which facility size possessed the highest chance of achieving profitability. The reason for this is that the technical and economic impact of small components were disregarded in the calculations. Additionally, these facilities were also assumed to operate with perfect insulation, meaning no occurrence of hydrogen leakage took place, which is not realistic in practice.

The objective of this research was to develop high performing polymer modified calcium sulfoaluminate (CSA) cement materials for use in applications requiring superior adhesion characteristics. Little information is available describing interactions of CSA cement containing minor phase tri-calcium aluminate (C3A) with commonly used admixtures. Given the scarcity of information, a basic approach for developing cementitious materials was followed. The basic approach consisted of four tasks: cement design, admixture design, polymer design and testing developed materials. The iterative, time consuming process is necessary for understanding the influence of specific constituent components on overall system behavior. Results from the cement design task suggest calcium sulfate type influences microstructural characteristics and strength development for materials based upon the experimental CSA cement. Results from the admixture design task suggest lithium carbonate and tartaric acid are effective accelerating and retarding admixtures for hydration reactions including reactants yeelimite, calcium sulfate and water. Results from the polymer design task suggest vinyl acetate / ethylene (VAE) dispersible polymer powders (DPP) are compatible with systems containing the experimental CSA cement and other commonly used admixtures. Additionally, results from the polymer design task highlight a method for specifying the ductile behavior of materials containing the experimental CSA cement as majority hydraulic binding agent. Finally, results from the testing of developed materials task suggests adhesion performance for materials containing the experimental CSA cement can be influenced by adjusting the ratio of polymer to hydraulic binding agent in material formulations. Polymer modified CSA cement mortars demonstrated bond strength resulting in substrate failure when cast over porous concrete substrates. Developed mortars demonstrated consistent bonding performance when applied to non-porous substrate materials, metal and glass. Select polymer modified mortars displayed adhesion bond performance such that the glass substrate materials fractured during pull off testing.

En ny komplex aspekt i frågan om vattenkvalité är ackumuleringen av organiska föroreningar.Den begränsade utbredningen av vattenrening i Brasilien såväl som i andra utvecklingsländervisar på ett tydligt behov av utveckling av billiga och effektiva metoder för provtagning ivatten. Bristen på den här typen av metoder försvårar idag möjligheterna att kontrolleravattenkvalitén och på så vis även arbetet med att säkerställa de sanitära förhållandena ivattentillgångar. Det här examensarbetet innehåller en sammanfattande genomgång avprinciperna för den passiva provtagningsmetoden med namnet ”Diffusive Gradients in Thin‐Films (DGT)”, som direktöversatt får det svenska namnet ”Diffusiva gradienter i tunnfilmer”.När metoden används för provtagning för att upptäcka olika organiska ämnen i vattnetbenämns den som o‐DGT.Målet med detta arbete är att ta fram en metod med målet att specifikt upptäcka olika typerav nya framväxande organiska föroreningar som i de flesta fall förekommer bara i väldigt lågakoncentrationer i vår miljö. Grundliga undersökningar genomfördes för att få svar på huruvidabiokol kan fungera som den bindande agenten i DGT apparatur och verka för att kunnaupptäcka och identifiera dessa ämnen på ett effektivt sätt.Resultaten från de undersökningar som genomförts hittills visar på att biokol har godpotential att tillämpas som bindande agent i filter för bruk i o‐DGT apparatur. De organiskaföreningarna av intresse i denna studie kunde alla detekteras, kvantifieras och identifieras.För optimering av provtagningsmetoden bör vidare studier vid varierande förhållanden medhänsyn till pH, temperatur och jonkoncentration genomföras, såväl som studier av detbindande lagrets egenskaper i förhållande till koncentration av biokol och lagrets tjocklek.Detta för att kunna optimera tekniken, och förhoppningsvis bidra till ett konventionelltanvändande av biokol på adsorberande agent i o‐DGT anordningar i framtiden. / A new complex aspect in the matter of water quality is the occurrence of emerging organicpollutants and contaminants in waste water. The currently low extent to which treatment ofwaste water is performed in Brazil, and in the world as a whole, there is a considerable needfor development of cheap and accurate in‐situ sampling methods for far‐reaching studies ofsurface water quality. The lack of such methods today makes the maintenance andestablishing of sanitary safety difficult. This diploma work gives a brief introduction to thebasic principles of the passive sampling method known as Diffusive Gradient in Thin‐films(DGT). A method that could be useful for such monitoring of quality in water bodies worldwide.The aim of this study is to develop a method, for the detection of organic emerging pollutantsand contaminants – i.e. compounds, which usually are present at very low concentrationswhen found in the environment as a result of human activity. More specifically, this workinvestigates the potential and usefulness of the application of DGT devices in detection oforganic compounds that can affect human health and ecosystems, even at lowconcentrations, however, their effects still are in need of further investigations.This study focuses on both purely technical as well as practical points of views. The efficiencyof organic DGT (o‐DGT) with biochar as the adsorbing agent is examined targeting thedetection of organic pollutants and contaminants in surface water. In this sense, the specificaim of the work is to evaluate the performance of biochar as adsorbing agent. This workshowed that the performance of biochar as the adsorbing agent in binding layers in o‐DGTsample devices can be considered as satisfactory since all compounds of interest in this studywas successfully detected, quantified an identified. Further investigations in the future areneeded to determine the effects of varying pH, temperature and ion concentration in thedeployment media, as well as the properties of the binding layer in relation to concentrationof biochar and the thickness of the layer. These in order to optimize the method for in‐situwater sampling, aiming conventional use of biochar as the adsorbing agent in the future.

Inledning En tredjedel av den mat som produceras i världen slängs (United Nations Development Programme [UNDP], 2020) och de livsmedelsförstörande mikroorganismerna är ett vanligt förekommande problem och en bidragande orsak till det globala matsvinnet (Snyder &amp; Worobo, 2018). Livsmedelsindustrin använder därför olika hurdletekniker för att minimera risken för tillväxt av förskämningsorganismer (Snyder &amp; Worobo, 2018). En strategi för att kontrollera om olika hurdletekniker uppfyller sitt syfte är att utsätta ett livsmedel för ett belastningstest. Syfte Syftet med studien var att genom ett belastningstest i ett flytande livsmedel jämföra konserveringsmedlen lingonjuice och kaliumsorbat + natriumbensoat samt att undersöka produktens fysikaliska och kemiska förändringar över tid.  Material och metod Ett flytande livsmedel (n = 73 á 180 ml) inokulerades i ett belastningstest med log 2–3 mikroorganismer per ml livsmedel. Därefter tillsattes konserveringsmedlen lingonjuice (n = 24) eller kaliumsorbat + natriumbensoat (n = 25). En tredjedel av proverna (n = 24) lämnades utan konserveringsmedel. Provtagning för analys av tillväxt, färg, pH och viskositet (mPas) utfördes vid 0, 14 och 30 dagar efter livsmedlet inokulerats med mikroorganismer.   Resultat Resultatet visade mikrobiell tillväxt i samtliga livsmedel vid dag 0. Dag 14 identifierades tillväxt i livsmedlet med kaliumsorbat + natriumbensoat samt lingonjuice. Vid analysen på dag 30 identifierades tillväxt i livsmedlet med kaliumsorbat + natriumbensoat och i livsmedlet utan konserveringsmedel. Över tiden skedde även fysikaliska förändringar i viskositet och kemiska förändringar av pH-värdet. Gällande färg skedde enbart marginella förändringar. Slutsats Resultatet av belastningstestet visade att lingonjuice är det konserveringsmedel som har bäst effekt med avseende på produktstabilitet genom att hämma tillväxt av tillsatta mikroorganismer. Resultaten av de fysikaliska mätningarna visade på förändringar över tid med avseende på viskositet. Färg visade enbart minimala förändringar. Resultatet av den kemiska mätningen visade på förändringar av pH-värdet över tid. / Introduction One third of food produced in the world is discarded (United Nations Development Program [UNDP], 2020) and food-destroying microorganisms are a common problem and a contributing cause of global food waste (Snyder &amp; Worobo, 2018). The food industry therefore uses various hurdle techniques to minimize the risk of growth of spoilage organisms (Snyder &amp; Worobo, 2018). One strategy to check whether different hurdle techniques meet their purpose is to expose foods in a challenge test. Aim The aim of the study was to compare the preservatives lingonberry juice and potassium sorbate + sodium benzoate and examine any physical and chemical changes over time through a challenge test on a liquid food product. Material and method A liquid food (n = 73 á 180 ml) was inoculated in a challenge test with log 2-3 microorganisms per ml food. Thereafter preservatives lingonberry juice (n = 24) or potassium sorbate + sodium benzoate (n = 25) were added. One third of the samples (n = 24) were left without preservatives. Sampling for analysis of growth, color, pH and viscosity (mPas) was performed at 0, 14 and 30 days after the food was inoculated with microorganisms. Results The results showed microbiological growth in all food products at day 0. Day 14 growth were found in the food with potassium sorbate + sodium benzoate and lingonberry juice. By the analysis on day 30 growth in the food with potassium sorbate + sodium benzoate and in the food without preservatives were showed. Over time physical changes of viscosity and chemical changes of pH occurred. Regard to color only marginal changes occurred. Conclusion The result of the challenge test showed that lingonberry juice is the preservative that has the best effect regard to product stability through inhibiting the added microorganisms. The results of the physical measurements showed changes regard to viscosity over time. Color only showed marginal changes. The result of the chemical measurement showed changes of pH over time.

Antibiotic resistance is a global and accelerating matter. Over time, the bacteria have evolved several defense mechanisms against the antibiotics. One of the defense mechanisms is that the bacteria can produce enzymes with the ability to hydrolyze the characteristic b-lactam ring of the antibiotics. These enzymes are called b-lactamases. There are three different generations of antibiotics clinically available, and b-lactamases have co-evolved with the antibiotics over the generations. The third generation of antibiotics are called the carbapenems and b-lactamases which hydrolyze carbapenems are called carbapenemases. Carbapenemases are promiscuous, which means that they hydrolyze a variety of antibiotics. The b-lactamase IMI-1 is an imipenem-hydrolyzing enzyme and imipenem is a carbapenem, hence IMI-1 is a carbapenemase. In this project, IMI-1 was investigated in complex with the carbapenems imipenem, meropenem and biapenem using computational methods. More specifically, a homology model of IMI-1 was generated and the carbapenems were docked into the model. The system was then used for MD simulations where the important molecular interactions were identified, and the binding free energies were calculated using the LIE method. The results indicate that IMI-1 has flexible loops that enables an open and a closed conformation of IMI- 1. All three carbapenems were docked and simulated in both conformations of IMI-1. The results indicate that open and closed conformations confirms the promiscuity of carbapenemases since the flexibility enables various initial binding mechanisms. in other words, the hydrolysis may occur so quickly that the binding does not have much bearing of the activity of the enzyme. Furthermore, the calculated binding free energies indicate that IMI-1 is optimized for the catalytic process rather than the binding affinity. In conclusion, IMI-1 and similar systems requires further research using computational methods to counteract antibiotic resistance based on knowledge.

Hydrogen has the potential to become an important energy carrier in the future with many areas of applications, as a clean fuel for transportation, heating, power generation in places where electricity use is not fit, etc. Already today hydrogen plays a key role in numerous industries such as petroleum refineries and chemical industries. There are different production methods for hydrogen. Today, natural gas reforming is the most commonly used. With the growing importance of green production paths, hydrogen production by electrolysis is expected to grow. Two main electrolyzer technologies are used today; alkaline and polymer electrolyte membrane electrolyzer. High-temperature electrolyzers are also interesting techniques, where solid oxide is under development and molten carbonate electrolyzers is researched. In this thesis, a comparative life cycle analysis was performed on the alkaline and molten carbonate electrolyzer. Due to inaccurate inventory data for the molten carbonate electrolyzer, those results are excluded from the published thesis. The environmental performance of the alkaline electrolyzer technology was compared to that of the solid oxide and the polymer electrolyte membrane electrolyzers. The system boundaries were set as cradle to gate. Thereby, the life cycle steps included in the study are raw material extraction, electrolyzer manufacturing, hydrogen production, and transports in between these steps. The functional unit was chosen as 100 kg produced hydrogen gas. The results show that the polymer electrolyte membrane electrolyzer has the lowest environmental impact out of the compared technologies. It is also determined that the lifetime and the current density of the electrolyzers have significant impact on their environmental performance. Moreover, it is established that electricity for hydrogen production has the highest environmental impact out of the electrolyzers life cycle steps. Therefore, it is important to make sure that the electricity used for hydrogen production derives from renewable sources. / Vätgas har potential att spela en viktig roll som energibärare i framtiden med många användningsområden, såsom ett rent bränsle för transporter, uppvärmning, kraftförsörjning där elproduktion inte är lämpligt, med mera. Redan idag är vätgas ett viktigt inslag i flera industrier, där ibland raffinaderier och kemiska industrier. Det finns flera metoder för att producera vätgas, där reformering av naturgas är den största produktionsmetoden idag. I framtiden spås vätgasproduktion med elektrolys bli allt viktigare, då hållbara produktionsprocesser prioriteras allt mer. Idag används främst två elektrolysörtekniker, alkalisk och polymerelektrolyt. Utöver dessa är högtemperaturelektrolysörer också intressanta tekniker, där fastoxidelektrolysören är under utveckling och smältkarbonatelektrolysören är på forskningsstadium. I det här examensarbetet har en jämförande livscykelanalys utförts på alkalisk- och smältkarbonatelektrolysören. På grund av felaktiga indata för smältkarbonatelektrolysören har dessa resultat uteslutits från den publika rapporten. Miljöpåverkan från den alkaliska elektrolysören har sedan jämförts med miljöpåverkan från fastoxid- och polymerelektrolytelektrolysörerna. Systemgränserna sattes till vagga till grind. De livscykelsteg som inkluderats i studien är därmed råmaterialutvinning, elektrolysörtillverkning, vätgasproduktion och transporter mellan dessa steg. Den funktionella enheten valdes till 100 kg producerad vätgas.  Resultaten visar att polymerelektrolytteknologin har den lägsta miljöpåverkan utav de tekniker som jämförts. Resultaten påvisar också att livstiden och strömtätheten för de olika teknikerna har signifikant påverkan på teknikernas miljöpåverkan. Dessutom fastslås att elektriciteten för vätgasproduktion har högst miljöpåverkan utav de studerade livscykelstegen. Därför är det viktigt att elektriciteten som används för vätgasproduktionen kommer ifrån förnybara källor.