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En konceptlösning för ett elektrovinningssystem utvecklas baserat på Glenngårds (2019) tidigare arbete. Arbetet är genomfört så att det besvarar tre frågor om en potentiell konceptlösning. Frågeställningarna inkluderar vilka krav som behöver uppfyllas, design av en passande arkitektur och hur vissa konceptparametrar kan verifieras. Krav formuleras i huvudsak baserat på Glenngårds parametrar; säkerhet, kvalitet, användarvänlighet, enkelhet att tillverka, montera, underhålla systemet, kostnadseffektivitet och användning av standardiserade komponenter. Konceptet som genereras är baserat på att använda en elektrolytbehållare kring vilken andra system är fästa eller indränkta. Designen tillåter en grad av automatisering. En bruksprocess för konceptet beskrivs, relevanta komponenter förklaras och vidare utveckling föreslås. En lista med föreslagna tester för verifikation med hjälp av prototypen är också given. / A concept solution for an electro winning system is developed based on the previous work done by Glenngård (2019). This project is made to answer three questions about a potential concept solution, including what requirements need to be fulfilled, design of a suitable architecture and how to verify certain parameters of the concept. Requirements are formulated mainly based on Glenngård’s parameters; safety, quality requirements, ease of use, ease of manufacturing, ease of assembly, ease of maintenance, cost efficiency and use of standardized components. The concept that is generated is based on a single electrolyte container around which surrounding systems are attached or immersed. The design allows a degree of automatization. A process of use is described, relevant components are explained, and further developments are suggested. A list of suggested tests to be carried out for verification using a prototype is also provided.

Detailed understanding of bubbles growing on a solid surface is a fundamental requirement in many technological domains, with particular application to water electrolysis in relation to the present-day socio-economic significance of clean energy transition. Evolution of bubbles at the electrode surface greatly determines the overall efficiency and throughput of an electrolysis cell. Bubbles residing on the electrode surface creates resistance to the flow of electric current and reduces the active electro-catalytic area. Therefore, fast removal of the bubbles is desirable for efficient operation. With this motivation, this dissertation aims to build deeper understanding of the bubble dynamics during the pre-detachment and detachment stage. To this end, single hydrogen bubbles grown on microelectrodes are chosen as the object of study. Thermocapillary and electric forces acting on an electrolytic bubble are introduced and a thorough account of the forces acting on the bubble is taken. A dynamical model of the bubble motion is developed. By means mathematical and physical modeling of the forces, working mechanism is provided for a novel mode of bubble detachment, namely oscillatory bubble detachment. The model predictions of oscillation parameters are in good correlation with experimental observations. Furthermore, the equation of motion of the bubble is shown to undergo bifurcation thus providing mathematical reasoning behind the existence of different detachment modes. A deeper look is taken specifically at the oscillatory mode. The electrolyte flow velocity is computed and compared with PTV based measurements. Force variation during one oscillation cycle is characterized and correlated with relevant geometric and operational parameters. Based on dynamical conditions of the bubble motion, the surface charge at the bubble interface is quantified. The calculated values match with literature values from bubble electrophoresis experiments. A detailed look is also taken at the effect of electrode size on the thermocapillary effect. The temperature and flow velocity field in the electrolyte is computed for various electrode size. Additional details regarding the flow structure were found. The location of the interfacial temperature hotspot was quantified. The current density distribution along the electrode surface was found to be strongly non-uniform. The Marangoni and the hydrodynamic force acting on the bubble was quantified at various electrode sizes. Further a model was developed to approximate the thermocapillary effect of a bubble on a large electrode. The location of temperature hotspot was found to be different when compared to bubbles on a microelectrode. This influences the Marangoni flow structure and also the Marangoni force on the bubble. Overall, this dissertation provides a systematic framework for characterizing forces acting on the bubble and investigating the dynamics of the bubble motion, which adds to our current understanding of bubble evolution and, takes one step towards predictive detachment models.

Hydrogen, as a dense energy carrier with low carbon footprint, will play an important role in energy transition. It only produces water after reaction which is totally environment friendly. There are many different technologies for hydrogen production. Steam Methane Reforming (SMR) is the most largely commercialized technology in the market, but it has a large carbon footprint in its conventional way. An Electrified Steam Methane Reforming (ESMR) has been proposed to improve the reforming efficiency and reduce the carbon footprint. By using biomethane as feedstock, the carbon footprint could be completely removed from the production itself. Water Electrolysis (WE) is now at the beginning stage of large-scale commercializing, but it’s limited due to the high energy consumption which makes this solution rather expensive. In order to decide which technology is better to cater to local climate policies and energy resources’ availabilities, a techno-economic study is essential for the market investigation. This work briefly introduced a technological comparison between the ESMR and WE technologies, followed by a techno-economic analysis in both grid-connected solutions and decentralized solutions. Biomethane is chosen as feedstock of ESMR technologies to produce greener hydrogen. In grid connected cases, the lowest and highest electricity price in SE1 to SE4 are considered to decide the Levelized Cost of Hydrogen (LCOH) range in these 4 areas for WE technologies, and together with the lowest and highest biomethane, LCOH for ESMR technologies are decided. In decentralized cases, wind farm and PV farm are considered to evaluate the LCOH of each technology. Generally speaking, in grid connected cases, SE1 and SE2 in Sweden are better locations to build up the hydrogen production plants due to the cheap electricity price there. ESMR is the least sensitive solution to electricity price fluctuation at an average rate 19.5%, while it’s 64.15% with PEM and 65.45% with AWE. Meanwhile ESMR is also the cheapest among all the technologies.In decentralized cases, wind farm solution is slightly cheaper than PV farm solution for all the technologies. Wind farm is feasible in whole Sweden while PV farm is only available in SE3 and SE4 in south of Sweden due to the geography and climate limitations which restricted the solar radiation conditions.When it comes to a specific solution, there are boundaries across different technologies, e.g., in ESMR, when the grid electricity price is lower than 715 SEK/MWh, grid connected ESMR is cheaper than wind farm ESMR, vice versa.

In municipal wastewater treatment, anaerobic digestion is the slowest process requiring at least 15 day solids retention time (SRT). Treating only a small fraction of the total wastewater stream, anaerobic digesters require large reactor volumes and consistent heating (40°C). Thus, there is a growing need to investigate techniques to improve digestion efficiency. The long SRT requirement is a result of the time required for biological reactions such as hydrolysis and acetoclastic methanogenesis. There are numerous pretreatment methods which have so far been developed to particularly enhance hydrolysis. These pretreatment methods include thermalization, mechanical treatments, and chemical treatments. These methods aim to increase the degradability of the influent waste sludge which in turn will increase the efficiency of the digestion process. The goal of the research presented in this thesis is to enhance another limiting biological reaction: acetoclastic methanogenesis. Microbial electrolysis cell (MEC) technology was integrated into lab-scale anaerobic digesters in order to accelerate biosolids destruction under various SRT and temperature conditions. Various mathematical simulations were conducted using a developed steady-state ADM1 (Anaerobic Digestion Model No.1) model to further evaluate the performance of the digesters. The results of the research indicate that the proposed method is effective at shortened SRTs (e.g., 6 days) and can enhance the stability of anaerobic digestion when exposed to variations in temperature and influent composition. / Thesis / Master of Applied Science (MASc)

Heavy metal contamination in water is a serious environmental and human health issue. Lead (Pb2+) and cadmium (Cd2+) are strictly regulated in wastewater effluent due to their high toxicity at low concentrations. Heavy metals are difficult to remove in conventional biological wastewater treatment because they are water soluble and non-biodegradable. Advanced treatment, such as tight membrane filtration and ion exchange, can be applied but they often require a high electrical energy input and a large amount of chemicals for pre- or post-treatment. Microbial electrolysis cells (MECs) can be used to treat wastewater while simultaneously recovering energy in the form of hydrogen gas. Additionally, MECs were proven to be effective for heavy metal removal. The commonly investigated removal mechanism for heavy metals in MECs is reduction at the cathode where heavy metal ions are reduced to metallic solids. The research presented in this thesis examined the effectiveness of cathodic reduction and other heavy metal removal mechanisms in MECs over a wide range of metal concentrations (10 μg/L-12 mg/L). Lab-scale MEC operation demonstrated successful removal of both Pb2+ and Cd2+ under different electric conditions, operation times, and initial metal concentrations. In addition to cathodic reduction, heavy metal removal in MECs was demonstrated through chemical precipitation at the cathode and electrochemical reduction and biosorption at the bioanode. The results of this research also confirmed the importance of microbial activity at the bioanode to efficiently drive the removal mechanisms in MECs. / Thesis / Master of Applied Science (MASc)

No description available.

Hydrogen is re-emerging as a serious alternative to fossil fuels. It is a clean gas with high energy density and its combustion only generates water vapour. Nevertheless, the hydrogen industry has a significant carbon footprint since this gas is mostly derived from fossil fuels reforming processes. This project focusses on the development of sustainable alternatives to conventional hydrogen production, in which approaches based on dark fermentation (DF) using an inexpensive residue from the brewery industry as primary feedstock are presented. Firstly, a fungal pre-treatment (FT) was proposed to degrade a high-strength brewery waste slurry (BWS) to obtain an effluent with a lower concentration of chemical oxygen demand (COD) but rich in readily fermentable sugars for the ensuing DF, thus improving hydrogen yields (HY). Secondly, microbial electrolysis and fuel cells (MECs and MFCs) were proposed to assist DF, generating electricity in MFCs while improving HY by MECs. Coupling both microbial electrochemical technologies sequentially after DF did not show any advantage. However, promising results were obtained for electricity and hydrogen production when taking a single-staged approach. Treating BWS directly by MFCs produced 2.0 watts/g COD consumed, while the DF process assisted simultaneously by MECs (DF/MEC) produced 1.6 times more hydrogen than DF alone. An average HY of 2.32 ± 0.06 mol H₂/mol glucose was attained between both DF/MEC and DF after FT, hence approaching the theoretical value of 2.4 mol H₂/mol glucose, representing roughly a 50% improvement compared to DF alone. With an overall COD reduction above 76%, the DF after FT exhibited the highest energy conversion rate per substrate consumed (6.3 kJ/g COD). As valuable by-products obtained, up to 31 g/L of fungal biomass, which is appreciated in many state-of-the-art biomaterials applications, was produced by using BWS. While in the DF/MEC process, 18 g/L of butyric acid were generated, which is three times more than with DF alone. Butyric acid being the precursor to butanol and building block of biodegradable thermoplastics, this result is not without significance. The proposed approaches not only valorize BWS but also validate their economic and environmental attractiveness as promising alternative hydrogen production methods.

The world energy production, transformation, storage, and usage are under a dramatic change. Actions are being taken by Governments to slow down the effects of the climate change. Wind energy is expected to be a central pillar for this change. However, a key issue facing the expansion of wind energy, especially in Sweden, is the integration of the massive amounts of new generation into the electricity grid (Energinet et al., 2021; Ingeberg, 2019; IVA, 2020). Another challenge facing the expansion of the wind energy is that it can’t be used by end-sector which rely on energy-dens carriers (IRENA, 2020b). In the pursuit of solutions to these challenges, green hydrogen produced by offshore wind energy emerges an alternative. Motivated by the recent Swedish plans to develop offshore wind power capacity in the Baltic Sea, as well as the problematic environmental statues in the Baltic Sea, this work investigate the cost of green hydrogen produced from offshore wind energy in Sweden and evaluates the environmental impacts of utilizing by-product oxygen on the marine ecosystem in the Baltic Sea.  The first step of this work considers the economic feasibility of a 2 GW offshore wind energy dedicated for hydrogen production in the Baltic Sea outside Sweden, with three alternative electrolyzer placement: onshore electrolyzer (III), centralized offshore electrolyzer (II), and decentralized offshore electrolyzer (I). The proposed assessment of this work investigated the hydrogen production cost using electricity from offshore wind energy in the Baltic Sea in Sweden. The LCoE and LCoH in relation to three configurations reflecting the electrolyzer placement were analyzed and compared. The electrolyzer operation at nominal capacities of 06%, 65%, and 70% were considered for the three configurations. The results shows that the LCoE and LCoH differed between the three configurations. The results showed that the lowest LCoE and LCoH is achieved by the configuration where the electrolyzer system decentralized at the turbine platform at a price of 1.7 €/kg. Reflecting the impact of the electrolyzer nominal capacities, which are at 60%, 65%, and 70%, on the LCoH, the result showed that the three configurations are equally competitive. However, when the nominal capacity of 65% were compared among the three configurations, it was showed that the LCoH at the onshore electrolyzer were 2.6 €/kg compared to the LCoH at the centralized electrolyzer which resulted in LCoH of 2.7 €/kg. The second step of this work considers the evaluation of the environmental impact of artificial oxygenation by reviewing existing studies. The results of the reviewed studies on the environmental impacts of artificial oxygenation indicate that the utilization of the by-product oxygen would contribute to important environmental benefits for the Baltic Sea. The use of the by-product oxygen to oxygenate would maintain the processes that removes nutrients, keep the sea water oxygenated, and the seabed habitable for marine animal. There are, however, some aspects that need to be considered and understood when planning for oxygenation, such as the complicated physical and biogeochemical interactions. Hence, this requires further studies and investigations.

The purpose of the following research is to explore molten regolith electrolysis (MRE) methodology for in-situ resource utilization (ISRU) of Highlands lunar regolith, to be explored during the initial Artemis missions. An analysis of potential commercial launch providers for MRE-equipment based on technology-readiness level (TRL), payload mass support, and $ USD/kg payload price is provided. SpaceX is ultimately proposed as a launch provider of MRE equipment following multi-factorial analysis, with the SpaceX Starship human landing system (HLS) variant proposed for supporting MRE payload. Finally, customers of regolith-derived oxygen, aluminum, and silicon are distinguished to form the business case for operating MRE equipment on the lunar surface.