Vasakronan is a real estate company with plans to build several geoenergy systems among other energy saving solutions to reduce 50 % of their buildings energy use. Each plant is designed by different constructors; thus, the design of the plants varies with both operating systems and construction. With this, Vasakronan has identified new challenges with managing, monitoring and operating optimization of the energy plants compared to the more commonly district heating plants. In order for Vasakronan to gain more control over the system design, this master thesis has investigated two different system for borehole energy storage solutions. One system by covering the cooling demand completely with free cooling from the boreholes and the second one by utilizing the buildings heat pump in cooling mode. Since the energy plants are affected by supply temperatures and COP, Vasakronan requested an investigation in how these systems should be adapted in a building with a geoenergy system.   The result showed that the system with free cooling had a lower cost over long time than the system with cooling operation, but was limited by the requirement for large ground areas for implementation of the system. Additionally, the supply temperature and COP had a larger impact to the total costs than the choice between the two systems in the short term.   An optimal geo energy plant for Vasakronan's office buildings would consist of high temperature cooling and low-temperature heating. The cooling requirement should be completely covered by free cooling as the cost of the system has low reinvestment, operation and maintenance costs in the long term. In cases where the ground area of the energy storage was limited for total free cooling, the cooling operation system should be built with the same supply temperatures in order to maintain the utilization rate of free cooling and high COP. / Fastighetsbolaget Vasakronan bygger samt planerar att bygga ett flertal geoenergianläggningar med långsiktigt mål att halvera energianvändningen för det nya och nuvarande fastighetsbeståndet. Varje anläggning projekteras av olika konstruktörer med varierande systemlösningar och konstruktion. I och med detta ser Vasakronan utmaningar med att hantera, följa upp och optimera anläggningarna i drift jämfört med ett enklare system som en fjärrvärmeanläggning. Då Vasakronan önskar bilda sig en uppfattning om hur en anläggning bör utformas, har detta examensarbete behandlat två olika och intressanta systemlösningar för borrhålsenergilager. Det första genom att täcka kylbehovet helt med frikyla från ett antal borrhål, och det andra systemet utnyttjar fastighetens värmepump även i kyldrift. Eftersom anläggningar påverkas av framledningstemperaturer och COP ville Vasakronan se hur dessa bör anpassas i en byggnad med en geoanläggning.   Resultatet visade att systemet med enbart frikyla hade en lägre kostnad på lång sikt än systemet med kyldrift, däremot begränsades systemet av stora markytor som krävs för placering av borrhålen. Dessutom hade framledningstemperatur och COP för de flesta fallen större påverkan på den totala kostnaden än valet mellan systemen på kort sikt.   En optimal geoanläggning för Vasakronans kontorsfastigheter, utifrån dem undersökta systemen, har högtemperaturkyla och lågtemperaturvärme för uppvärmning respektive komfortkyla. Kylbehovet bör täckas helt med frikyla då kostnaden för systemet på lång sikt har låga reinvesterings-, drift och underhållskostnader. I fallen då ytan för energilagret inte finns, bör systemet med kyldrift byggas med samma framledningstemperaturer för att bibehålla utnyttjandegraden av frikyla och höga COP.

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Natural graphite, a type of carbon, is used in most battery driven electronic devices around the world as it serves as the anode in Li-ion batteries. Since 67\% of global production of graphite originates from a single country the EU has classified it as a critical raw material with a high supply risk. If graphite can be produced locally from biomass not only would it potentially make batteries cheaper it could be a huge boon to the Swedish bio industry. In this thesis carbonization of pure lignin is done through hydrothermal carbonization and slow pyrolysis with peak temperature of 900\degree C. The type of carbon needed for these applications involves a high degree of crystallization and large surface areas and pore volumes. Analysis of the samples was done through X-Ray Diffraction, Raman spectroscopy, CHNO- and specific surface analysis. Results show a D/G ratio of 0.85, full width half maximum (FWHM) values of 7.7, which points toward a hard carbon with nano crystalline graphite present in the samples. SSA results show a Brunauer–Emmett–Teller (BET) surface area of around 350 $m^2/g$ and CHNO show a carbon content of about 90\%. The results are promising for use as an anode in hard carbon sodium-ion batteries or for $CO_2$ separation. Techno-economical analysis show that integrated biocarbon production in a bio-ethanol plant is a much more profitable solution than selling the lignin as biofuel or burning it for electricity production.

<p> A CAT C6.6 turbocharged diesel engine was operated in dual-fuel diesel-hydrogen mode. Hydrogen was inducted into the intake and replaced a portion of the diesel fuel. Hydrogen was added across multiple engine speeds and loads until reaching the knock limit, identified by a threshold on the rate of in-cylinder pressure rise. In-cylinder pressure and emissions data were recorded and compared to diesel-only operation. Up to 74% H₂ substitution for diesel fuel was achieved. Hydrogen addition increased thermal efficiency up to 32.4%, increased peak in-cylinder pressure up to 40.0%, increased the maximum rate of pressure rise up to 281%, advanced injection timing up to 13.6&deg;, increased NO_x emissions up to 224%, and reduced CO₂ emissions up to 47.6%. CO and HC emissions were not significantly affected during dual-fuel operation. At 25% load an operating condition was observed with low NO_x and nearly 0 CO₂ emissions, which however exhibited unstable combustion.</p>

<p> This research develops a comprehensive methodology and model for accurate prediction of power losses caused by nonuniform electrical characteristics and operating conditions in grid-tied photovoltaic systems, as well as the potential for increased energy capture in systems which employ sub-array power optimizers (microconverters or microinverters). Investigation of these topics provides a framework for more accurate loss modeling and determination of power optimizers' value in a variety of scenarios, enabling future PV research and maximizing the value of PV systems in the built environment. </p><p> A custom multitracer, which records simultaneous module-level I-V curves, is designed and built to collect data on 27 PV installations in the Southwestern U.S. The resulting measured dataset, including over 500 modules of crystalline silicon and thin film technologies, indicates that commonly-used, single diode PV generator modeling methodologies often incorrectly predict PV performance at low and medium light levels. A new modeling methodology and parameters are proposed, demonstrating an improved way to incorporate low light data to increase prediction accuracy for crystalline silicon and thin film arrays. </p><p> A unique, detailed annual simulation environment for PV system modeling is developed, allowing user-input electrical characteristics and operating conditions at the PV cell level. It is designed specifically to model electrical mismatch and partial array shading, and use of power optimizers to mitigate related energy losses. The resulting simulations, combined with the module-level I-V curve dataset, are used to predict annual mismatch losses caused by module-to-module performance variation in each monitored array. The losses, representing energy that may be directly recovered using power optimizers, are moderately low for most of the tested arrays. </p><p> Annual simulations of realistic shading scenarios and PV array configurations show percent annual energy losses that are 2&ndash;3 times the annual percent incident light lost in partially shaded arrays. Sub-module or even module level simulations predict nearly the same shading losses as cell level simulations, demonstrating opportunities for model simplification. Arrays with power optimizers can recover 30&ndash;45% of the energy loss. In the example scenarios, power optimizers are most advantageous at the module or cell levels, adding little benefit at the string or bypass diode sub-module levels.</p>

<p> Vanadium oxide has emerged as a potential electrochemical capacitor material due to its attractive pseudocapacitive performance; however, it is known to suffer from capacitive degradation upon sustained cycling. In this work, the electrochemical cycling behavior of anodically electrodeposited vanadium oxide films with various surface treatments in aqueous solutions is investigated at different pH. Quantitative compositional analysis and morphological studies provide additional insight into the mechanism responsible for capacitive degradation. Furthermore, the capacitance and impedance behavior of vanadium oxide electrochemical capacitor electrodes is compared for both aqueous and nonaqueous electrolyte-solvent systems. Alkali metal chloride and bromide electrolytes were studied in aqueous systems, and nonaqueous systems containing alkali metal bromides were studied in polar aprotic propylene carbonate (PC) or dimethyl sulfoxide (DMSO) solvents. The preferred aqueous and nonaqueous systems identified in the half-cell studies were utilized in symmetric vanadium oxide whole-cells. An aqueous system utilizing a 3.0 M NaCl electrolyte at pH 3.0 exhibited an excellent 96% capacitance retention over 3000 cycles at 10 mV s^-1. An equivalent system tested at 500 mV s^-1 displayed an increase in capacitance over the first several thousands of cycles, and eventually stabilized over 50,000 cycles. Electrodes cycled in nonaqueous 1.0 M LiBr in PC exhibited mostly non-capacitive charge-storage, and electrodes cycled in LiBr-DMSO exhibited a gradual capacitive decay over 10,000 cycles at 500 mV s^-1. Morphological and compositional analyses, as well as electrochemical impedance modeling, provide additional insight into the cause of the cycing behavior. Lastly, reduced graphene oxide and vanadium oxide nanowire composites have been successfully synthesized using electrophoretic deposition for electrochemical capacitor electrodes. The composite material was found to perform with a higher capacitance than electrodes containing only vanadium oxide nanowires by a factor of 4.0 at 10 mV s^-1 and 7.5 at 500 mV s^-1. The thermally reduced composite material was examined in both symmetric and asymmetric whole cell electrochemical capacitor devices, and although the asymmetric cell achieved both higher energy and power density, the symmetric cell retained a higher capacitance over 50,000 cycles at 200 mV s^-1.</p>

<p> During the last several decades engineers and scientists put significant effort into developing reliable and efficient wind turbines. As a wind power production demands grow, the wind energy research and development need to be enhanced with high-precision methods and tools. These include time-dependent, full-scale, complex-geometry advanced computational simulations at large-scale. Those, computational analysis of wind turbines, including fluid-structure interaction simulations (FSI) at full scale is important for accurate and reliable modeling, as well as blade failure prediction and design optimization. </p><p> In current dissertation the FSI framework is applied to most challenging class of problems, such as large scale horizontal axis wind turbines and vertical axis wind turbines. The governing equations for aerodynamics and structural mechanics together with coupled formulation are explained in details. The simulations are performed for different wind turbine designs, operational conditions and validated against field-test and wind tunnel experimental data.</p>

<p> The <i>Cool Robot</i> is a solar powered autonomous robot designed to support summertime science campaigns in the Polar Regions. While the overall design was proven in a previous deployment to Summit Greenland, it lacked the robustness for longer campaigns, and the ergonomics of accessing the interior of the robot were arduous and time consuming. The objectives of this thesis were to 1) redesign the solar panel system for improved performance in wind and rough terrain and for easier assembly and access to inside of the robot chassis, 2) update the power system controls and electronics for reliable and robust operation, 3) update all electrical systems using common, off-the-shelf components, 4) establish a common code base and communication protocol used by other similarly designed robots, 5) provide permanent data logging capability to evaluate mobility and the power system performance, and 6) develop and implement a sensor-based framework for detecting and avoiding dangerous levels of tilt which could result in roll-over. All of these objectives aim to increase the performance reliability of the <i>Cool Robot</i>. The data logging capability allows for collecting data to evaluate performance of the new power system. The reliability of the <i>Cool Robot</i> will be tested during a summer mission to Summit Greenland.</p>