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Europe aims for a transition towards less greenhouse gas emission and dependency on fossil fuels. The integration of intermittent renewable energy sources, as wind or solar power, can be facilitated by, among others, temporally decoupling demand and supply of electricity. If technologies for electrical energy storage are profitable, wide implementation could support the transition. Therefore, this study assesses the revenues and costs of long-term storage technologies and evaluates the possibility to stack several services provided by a storage unit to fully utilise it. Key market characteristics influential on storage potential are outlined and used to classify and compare the demand for storage in European markets. Considering them market clusters are formed comprising of countries with similar electricity market and from these two contrasting archetypal countries are chosen for further evaluation, Sweden and Germany. Storage technologies, as pumped hydro or compressed air, are delineated by essential technical specifications and used to determine the compatibility of them to corresponding services. A process for combining multiple services for a single storage unit is designed and employed to develop five cases. The results show that providing multiple services device can improve the profitability of the designed business cases by generating multiple revenue streams and increase the value to the electricity system. The stacking also minimises the storage’s idle time. Furthermore, the results demonstrate the influence of the key characteristics on the economic viability of the electrical energy storage in European markets. / Europa eftersträvar en övergång från att släppa ut mindre växthusgaser och minska eroendet av fossila bränslen. Att implementera förnybara energikällor, som vindkraft ller solenergi, kan underlättas genom att bland annat genom att tillfälligt rikoppla efterfrågan och leveransen av el. Om tekniken för energilagring är lönsam, an genomförande därför stödjas. Denna studie beskriver därför både intäkter ch kostnader för långsiktiga lagringstekniker och utvärderar även möjligheten att mplementera flera tjänster som tillhandahålls av en lagringsenhet till att kunna tnyttja denna till fullo. Marknaden av lagring kännetecknas redan ha potentiella förutsättningar och att den an användas för att klassificera och jämföra efterfrågan för lagring på de europeiska arknaderna. En marknadsanalys har valts att genomförts av länder med likartad lmarknad och de två länder som har välts ut för en vidare utvärdering är Sverige ch Tyskland. Lagringsteknik som vattenkraft som pumpas eller tryckluft, beskrivs ärmare med tekniska förutsättningar och används för att beskriva kompatibiliteten v tekniken och tjänsterna. Ett förfarande för att leverera flera tjänster från en enda innesenhet är utformad och används för att utveckla fem beskrivande fall. Resultatet visar att tillhandahålla flera tjänster från en enda lagringsenhet förbättrar önsamheten för affärsidéer genom att generera flera intäktsströmmar och ökar ärdet till elsystemet. Stapling minimerar också lagring är ledig tid. Dessutom visar esultatet om hur de viktigaste egenskaperna påverkas av de ekonomiska affärsmodellerna.

Global concern about climate change and its impacts on the environment isprogressively increasing. This has raised an important issue in the buildings andconstruction industry regarding the effects of climate change on the buildingenergy performance. Currently, many residential buildings do not fulfill theenergy requirements even with the current weather conditions, mainly becauseof poor design or because the buildings are designed according to olderregulations. Consequently, there is a need for significant changes in the buildingdesign and construction in order to create a more sustainable built environmentwith lower energy consumption. However, it is not possible to change all thesebuildings in order to meet the needs of today. It is therefore of utmostimportance that the energy production comes from renewable sources as ameans to mitigate the potential environmental impacts of climate change.In Sweden, the field of renewable energy has seen a significant growth inrecent years, and particularly in Gotland, where the project under investigationis located. In Gotland, several wind farms and wind turbines have already beeninstalled in order to benefit from the advantageous wind conditions of the island.However, the development of the project for improving the connection ofGotland’s electricity grid with the Swedish mainland power grid has come intoa halt since 2017, and Gotland is now facing major issues in terms of electricityconsumption. And as climate change only escalates in the future, it is crucial toaddress this issue. Through an extensive study of the residential sector ofGotland, this thesis examines the buildings’ energy performance with theintention of finding and proposing possible solutions and alternatives that caneventually flatten the peaks in the energy consumption of the built environmentin Gotland.

The objective of this thesis was to assess the market opportunities for two novel Carnot battery system solutions, one supplying power and low temperature heat as well as a system supplying medium temperature heat exclusively. To fulfill the objective, a methodology was developed and implemented to investigate the market potential, further two techno-economic models were developed and utilized to investigate the performance of such Carnot battery solutions. Based on the market review four industrial sectors were identified as most interesting and the geographical scope was confined to Europe. Further, case studies were developed to mimic two different sizes of manufacturing plants, a small and large, for the identified sectors. The cases were then implemented to the techno-economic analysis to compare the performance of a new Carnot battery system against the conventional energy solutions. The identified market offers a vast opportunity for incorporating Carnot battery solutions to meet the industrial sectors requirements, both from a technical and market size perspective. The market review combined with the techno-economic analysis indicates that the heat market is interesting as long as fuel, power grid costs and industrial operations are at the ideal level. For the Carnot battery system supplying both power and heat, it was found that yearly cost savings in the range of 10-15 % could be achieved for the identified market. The added value of incorporating heat generation and surplus power from PV had a strong effect on the business case. Through sensitivity analysis it was approximated that locations in central/south Europe with global horizontal irradiance (GHI) above 1500 kWh/m2 would benefit from the solution. For the Carnot battery system supplying medium temperature heat it was found that solutions would struggle with feasibility for the given market conditions. Through sensitivity it was found that locations with GHI higher than 2100 kWh/m2 would benefit from the solution. For both models it was found that the hybrid solution, Carnot battery combined with on-site PV, yields the most feasible solution for the end user, compared to charging the Carnot storage system from the power grid. Both models were sensitives to changes in energy cost for operating the old conventional system as well as operations times of the industries. The availability of space is a major constraint to implement Carnot battery solutions, as both the Carnot battery as well as PV plant require substantial space. It was found through literature and interviews that industries with close proximity to end customer and which faces pressure to decarbonize, may be most interesting to target, as for e.g. the Food and beverage sector. / Syftet med denna uppsats var att undersöka marknadspotentialen för två stycken Carnot batterisystem, ett system som generar både el och låg tempererad värme och ett som endast generar medel tempererad värme. För att uppnå målet så utvecklades och implementerades en metod för att undersöka marknadspotentialen, vidare så utvecklades och användes två tekno-ekonomiska modeller för att undersöka prestandan för de två Carnot lösningarna. Baserat på marknadsundersökningen så identifierades fyra industriella sektorer som mest intressanta och baserat på dem begränsades omfattningen av studien till Europa. Från marknadsgenomsökningen och de identifierade industriella sektorerna skapades två olika profiler för att representera en liten och stor industri för de identifierade sektorerna. Profilerna användes som utgångspunkt för den tekno-ekonomiska analysen för att jämföra prestandan hos ett nytt Carnot batterisystem mot konventionella energilösningar. Den identifierade marknaden erbjuder en stor möjlighet för att integrera Carnot batterilösningar för att möta industrisektorns krav, både ur ett tekniskt perspektiv och med tanke på marknadensstorleken. Marknadsundersökningen kombinerat med tekno-ekonomiskanalysen indikerar att värmemarknaden för industrier är intressant så länge bränsle- och elkostnader samt drifttiden är i rättnivå. Resultat från analysen tyder på att Carnot batterilösningar, som generar både el och värme, kan skapa energikostnadsbesparingar runt 10–15 % för den identifierade marknaden. Värdet av att addera kassaflöden från överskotts el från solcellerna samt värmegenerering har en stark påverkan på resultaten. Från en känslighetsanalys gick det att identifiera centrala/södra Europa som platser med tillräcklig solinstrålning (runt 1500 kWh/m2) för att dra nytta av ett Carnot batteri. För Carnot batterisystemet som endast producerar medel tempererad värme så skapas inga energikostandsbesparingar för slutanvändaren för den analyserade marknadsförutsättningarna. Genom en känslighetsanalys gick det att fastställa att hög solinstrålning krävs (över 2100 kWh/m2) för att slutanvändaren ska skapa några besparingar med systemet. För båda modellerna generade en hybridsystemlösning med både Carnot batteri samt lokal solcellsanläggning de bästa resultaten, jämfört med om systemet skulle laddas från elnätet. Båda modellerna är känsliga mot förändringar i energikostnader, värme eller el, för det konventionella systemet samt lägre drifttid. Vidare så är tillgänglig yta en annan restriktion som både kan hindra implementeringen av Carnot batteriet samt också solcellsanläggningen. Både litteraturstudien och de genomförda intervjuerna tyder på att industrier som har nära kontakt med slutkonsumenten och som har krav på att reducera sin miljöpåverkan, är en intressant användare av ett Carnot batterilösning, som exempelvis livsmedelsindustrin.

Det finns en ökande efterfrågan på förnybar elproduktion och effektiva lösningar att kombinera med denna. Ett flertal tidigare arbeten har undersökt energilagringssystem (ESS) och dess lönsamhet i olika tillämpningar. Det råder en osäkerhet kring lönsamheten hos ESS för ökad självkonsumtion i Sverige. Detta arbete undersöker lönsamheten hos batterilagringssystem (BESS) som används i syftet att öka självkonsumtionen för aktörer med solceller i den svenska bostadssektorn. En modell konstruerades baserat på Levelized Cost of Storage (LCOS), och indata till modellen varierades för olika scenarier. Resultaten visade att BESS kostnader i dagsläget är för höga, med LCOS mellan 1,68 kr/kWh och 3,56 kr/kWh beroende på aktör och indata. För lönsamhet krävs reduktion av LCOS mellan 55% och 85%. Vidare undersöker arbetet vilka variabler som har störst påverkan på BESS lönsamhet. En känslighetsanalys genomfördes, där CAPEX, antalet battericykler per år, WACC och skattereduktioner vid elhandel identifierades som viktiga variabler. Arbetet visade att det antagligen krävs en kombination av högre elpriser och reducerade investeringskostnader för att motivera en investering i BESS. Utöver ökad självkonsumtion behövs ytterligare värden för att motivera en investering i BESS inom en snar framtid. / There is a growing demand for renewable power generation and efficient solutions to combine with renewables. Previous works have explored energy storage systems (ESS) and their profitability in various applications. There is an uncertainty about the profitability of ESS for increased self-consumption in Sweden. This thesis explores the profitability of battery energy storage systems (BESS) used for increased self-consumption for stakeholders with solar photovoltaics in the Swedish residential sector. A model based on levelized cost of storage (LCOS) was constructed, and varying input values were used for different scenarios. The results showed that the current cost of BESS is too high, with LCOS ranging between 1,68 SEK/kWh and 3,56 SEK/kWh depending on the stakeholder as well as input data. For profitability, a reduction of LCOS between 55% and 85% is needed. Furthermore, this thesis explores which variables have the greatest effect on a BESS’s profitability. A sensitivity analysis was conducted, where CAPEX, the number of battery cycles per year, WACC and tax reductions linked to electricity trading were identified as important variables. This thesis concluded that higher electricity prices in combination with reduced investment costs is needed to justify an investment in BESS. Besides increased self-consumption, other values are needed to justify an investment in a BESS in the near future.

<p>No comments. Thanks.</p> / <p>Advanced electrodes based on MnO₂ for the electrochemical supercapacitor (ES) application have been fabricated using electrochemical and chemical methods.</p> <p>Electrosynthesis method has been utilized for the in-situ impregnation of manganese dioxide in commercial Ni plaque current collectors. Dipping-reduction, cathodic galvanostatic and reverse pulse electrosynthesis methods were investigated. The material loading was varied by the variation of the number of the dipping-reduction procedures in the chemical precipitation method or by the variation of charge passed in the electrochemical methods. The results obtained by different methods were compared. The dipping-reduction method offered the advantage of higher specific capacitances (SCs) at high scan rates, whereas other methods allowed higher material synthesis rate.</p> <p>Cathodic electrolytic deposition (ELD) has been utilized for the fabrication of Ag-doped MnO₂ films. The Ag-doped MnO₂ films showed improved capacitive behavior and lower electrical resistance of 0.6 Ohm compared to pure MnO₂ films. The highest SC of 770 F g^-1 was obtained at a scan rate of 2 mV s^-1 in the 0.5 M Na₂SO₄ electrolyte.</p> <p>Electrodes for ES application were fabricated by cathodic electrodeposition of MnO₂ on CNTs, which were grown by chemical vapor deposition on stainless steel meshes. The MnO₂-CNT nanocomposites showed excellent capacitive behavior and low electrical resistance of 0.5 Ohm.</p> <p>Electrophoretic deposition (EPD) has been utilized for the deposition of composite MnO₂-multiwalled carbon nanotube (MWCNT) films for the ES application. Dopamine (DA), caffeic acid (CA), tyramine (TA), gallic acid (GA), polyacrylic acid (PAA) and pyrocatechol violet (PV) were shown to be effective and universal charging additives, which provide stabilization of MnO₂ nanoparticles and MWCNTs in the suspensions. The influence of the structure of the organic molecules on their adsorption on the oxide nanoparticles has been investigated. We discovered that the number and site of OH group for dispersants were essential for the adsorption on oxide materials, and the number of aromatic ring was important for the adsorption on carbon materials. Pure CNT films were deposited using PV as a dispersant, which was the first time in literature to prepare pure CNT film using a dispersant. SCs decrease with increasing film thickness. SCs of composite MnO₂-MWCNT obtained using EPD were in the range of 350-650 F g^-1 depending on material loadings.</p> / Doctor of Science (PhD)

Thermal energy storage systems as an integral part of concentrated solar power plants improve the performance of the system by mitigating the mismatch between the energy supply and the energy demand. Using a phase change material (PCM) to store energy increases the energy density, hence, reduces the size and cost of the system. However, the performance is limited by the low thermal conductivity of the PCM, which decreases the heat transfer rate between the heat source and PCM, which therefore prolongs the melting, or solidification process, and results in overheating the interface wall. To address this issue, heat pipes are embedded in the PCM to enhance the heat transfer from the receiver to the PCM, and from the PCM to the heat sink during charging and discharging processes, respectively. In the current study, the thermal-fluid phenomenon inside a heat pipe was investigated. The heat pipe network is specifically configured to be implemented in a thermal energy storage unit for a concentrated solar power system. The configuration allows for simultaneous power generation and energy storage for later use. The network is composed of a main heat pipe and an array of secondary heat pipes. The primary heat pipe has a disk-shaped evaporator and a disk-shaped condenser, which are connected via an adiabatic section. The secondary heat pipes are attached to the condenser of the primary heat pipe and they are surrounded by PCM. The other side of the condenser is connected to a heat engine and serves as its heat acceptor. The applied thermal energy to the disk-shaped evaporator changes the phase of working fluid in the wick structure from liquid to vapor. The vapor pressure drives it through the adiabatic section to the condenser where the vapor condenses and releases its heat to a heat engine. It should be noted that the condensed working fluid is returned to the evaporator by the capillary forces of the wick. The extra heat is then delivered to the phase change material through the secondary heat pipes. During the discharging process, secondary heat pipes serve as evaporators and transfer the stored energy to the heat engine. Due to the different geometry of the heat pipe network, a new numerical procedure was developed. The model is axisymmetric and accounts for the compressible vapor flow in the vapor chamber as well as heat conduction in the wall and wick regions. Because of the large expansion ratio from the adiabatic section to the primary condenser, the vapor flow leaving the adiabatic pipe section of the primary heat pipe to the disk-shaped condenser behaves similarly to a confined jet impingement. Therefore, the condensation is not uniform over the main condenser. The feature that makes the numerical procedure distinguished from other available techniques is its ability to simulate non-uniform condensation of the working fluid in the condenser section. The vapor jet impingement on the condenser surface along with condensation is modeled by attaching a porous layer adjacent to the condenser wall. This porous layer acts as a wall, lets the vapor flow to impinge on it, and spread out radially while it allows mass transfer through it. The heat rejection via the vapor condensation is estimated from the mass flux by energy balance at the vapor-liquid interface. This method of simulating heat pipe is proposed and developed in the current work for the first time. Laboratory cylindrical and complex heat pipes and an experimental test rig were designed and fabricated. The measured data from cylindrical heat pipe were used to evaluate the accuracy of the numerical results. The effects of the operating conditions of the heat pipe, heat input, and portion of heat transferred to the phase change material, main condenser geometry, primary heat pipe adiabatic radius and its location as well as secondary heat pipe configurations have been investigated on heat pipe performance. The results showed that in the case with a tubular adiabatic section in the center, the complex interaction of convective and viscous forces in the main condenser chamber, caused several recirculation zones to form in this region, which made the performance of the heat pipe convoluted. The recirculation zone shapes and locations affected by the geometrical features and the heat input, play an important role in the condenser temperature distributions. The temperature distributions of the primary condenser and secondary heat pipe highly depend on the secondary heat pipe configurations and main condenser spacing, especially for the cases with higher heat inputs and higher percentages of heat transfer to the PCM via secondary heat pipes. It was found that changing the entrance shape of the primary condenser and the secondary heat pipes as well as the location and quantity of the secondary heat pipes does not diminish the recirculation zone effects. It was also concluded that changing the location of the adiabatic section reduces the jetting effect of the vapor flow and curtails the recirculation zones, leading to higher average temperature in the main condenser and secondary heat pipes. The experimental results of the conventional heat pipe are presented, however the data for the heat pipe network is not included in this dissertation. The results obtained from the experimental analyses revealed that for the transient operation, as the heat input to the system increases and the conditions at the condenser remains constant, the heat pipe operating temperature increases until it reaches another steady state condition. In addition, the effects of the working fluid and the inclination angle were studied on the performance of a heat pipe. The results showed that in gravity-assisted orientations, the inclination angle has negligible effect on the performance of the heat pipe. However, for gravity-opposed orientations, as the inclination angle increases, the temperature difference between the evaporator and condensation increases which results in higher thermal resistance. It was also found that if the heat pipe is under-filled with the working fluid, the capillary limit of the heat pipe decreases dramatically. However, overfilling of the heat pipe with working fluid degrades the heat pipe performance due to interfering with the evaporation-condensation mechanism. / Mechanical Engineering

Concerns with emissions, CO2 in particular, and energy resource associated with conventional internal combustion engine (ICE) vehicles is motivating a shift towards more electrified power-trains for road transportation, as well as other transportation applications. The modelling, characterization and design of electrified power-trains, including energy storage technologies, traction machine technologies and their associated power electronics, are discussed in this thesis. Port cranes are a special case of land transportation encompassing many of the power-train objectives found common with road based hybrid electric vehicles; here a port crane system is studied. The power flow for a typical crane loading cycle is analyzed and the value of the energy consumption and saving potential is calculated. Then alternative energy storage applications are considered for hybrid power-train configurations employing diesel engine generators, battery packs, supercapacitors (SCs), and flywheels. A hybrid rubber tyred gantry crane (RTGC) power-train model with power management is developed and the battery-SC hybrid energy storage systems are designed for both short- and long-period operation. The Induction machine (IM) is a popular technology for traction applications. Although many publications discuss IM design to realize a traction torque-speed characteristic, the IM model is studied to determine the main parameters impacting on the machine performance capability at constant torque and extended speed. Based on the model analysis, an IM design procedure for traction applications is proposed which improves machine performance capability. The machine design parameters are normalized in per unit form and hence the proposed design procedure is applicable across different ratings. In the specification and definition of vehicle power-trains, it is common (in industry) to quote data at specific operating conditions, for example, full or fixed battery terminal voltage and system temperature. The interactive influence between energy storage devices and the vehicle system is investigated. Using the all-electric Nissan Leaf power-train as a reference example, the Nissan Leaf traction system is evaluated and performance assessed by considering DC-link voltage variation from battery full state of charge (SoC) to zero SoC and temperature variations typical of an automotive application, showing that the system stated performance is reduced as battery SoC decreases. An alternative traction machine design is proposed to satisfy the vehicle target performance requirements over the complete variation of SoC. The vehicle power-train is then modified with the inclusion of a DC/DC converter between the vehicle battery and DC-link to maintain the traction system DC-link voltage near constant. A supercapacitor system is also considered for improved system voltage management. The trade-offs between the actual Nissan Leaf power-train and the redesigned systems are discussed in terms of electronic and machine packaging, and mitigation of faulted operation at high speeds. Using the Nissan Leaf interior permanent magnet (IPM) machine as the benchmark machine, an example surface permanent magnet (SPM) machine, with same design constraints, is designed and compared with the benchmark IPM machine. The phase voltage distortion of IPM and SPM machines are compared and the mechanisms are revealed. An alternative machine topology with pole shoe rotor is proposed for reduction of machine peak current rating and voltage distortion. The pole shoe topology is common in industrial variable speed drives employing constant torque regimes, but not for traction. Here, the machine with pole shoe rotor is designed to achieve traction performance. The pole shoe concept for vehicle traction is significantly different from existing practice in the electric and hybrid electric automotive industry and thus departure in standard design is a contribution of this thesis. / Thesis / Doctor of Philosophy (PhD)

This thesis suggests a new approach to extend the lifetime of Lithium-ion batteries for a Home Energy Storage System equipped with a renewable energy source. The new configuration improves the lifetime of the energy storage device by using the pulsed charge-discharge method. The batteries in this system can be charged either using solar panels when solar energy is available or by the grid power during off-peak hours when the electricity cost is at its lowest rate. In the new configuration, the battery bank is split into two equal sections to employ pulsed charge-discharge method. Interrupting the charge or discharge current provides a relaxation time for the lithium ions to diffuse gradually into the electrodes material of Lithium-ion batteries, this reduces the damage in the microstructure of the electrodes and thus it helps to prolong the battery lifetime. The spilt bank strategy improves the longevity of Lithium-ion batteries while maximizing the solar energy utilization. This strategy leads to reduce the reliance on the grid power which decreases the consumer’s total energy cost as well. To show the usefulness of the new approach, different modes of operation are discussed in details along with simulation results. An experimental setup is also developed to evaluate the effectiveness of the new approach in extending the Lifetime of Lithium-ion batteries. / Thesis / Master of Applied Science (MASc)

Energy demand for buildings has been rising during recent years. Increasing building energy consumption has caused many energy-related problems and environmental issues. The on-site community energy system application is a promising way of providing energy for buildings. Community energy system usage reduces the primary energy consumption and environmental effects of greenhouse gas (GHG) emissions compared to the implementation of the stand-alone energy systems. Furthermore, due to the increase in electricity price and shortage of fossil fuel resources, renewable energies and energy storage technologies could be great alternative solutions to solve energy-related problems. Generally, the energy system might include various technologies such as internal combustion engine, heat recovery system, boiler, thermal storage tank, battery, absorption chiller, ground source heat pump, heating coil, electric chiller, solar photovoltaics (PV) and solar thermal collectors, and seasonal thermal energy storage. The economic, technical and environmental impacts of energy systems depend on the system design and operational strategy. The focus of this thesis is to propose unified frameworks, including the mathematical formulation of all of the components to determine the optimal energy system configuration, the optimal size of each component, and optimal operating strategy. The proposed methodologies address the problems related to the optimal design of the energy system for both deterministic and stochastic cases. By the use of the proposed frameworks, the design of the energy system is investigated for different specified levels of GHG emissions ratio, and the purpose is to minimize the annual total cost. To account for uncertainties and to reduce the computational times and maintain accuracy, a novel strategy is developed to produce scenarios for the stochastic problem. System design is carried out to minimize the annual total cost and conditional value at risk (CVaR) of emissions for the confidence level of 95%. The results demonstrate how the system size changes due to uncertainty and as a function of the operational GHG emissions ratio. It is shown that with the present-day technology (without solar technologies and seasonal storage), the lowest amount of GHG emissions ratio is 37%. This indicates the need for significant technological development to overcome that ratio to be 10% of stand-alone systems. This thesis introduces novel performance curves (NPC) for determining the optimal operation of the energy system. By the use of this approach, it is possible to identify the optimal operation of the energy system without solving complex optimization procedures. The application of the proposed NPC strategy is investigated for various case studies in different locations. The usage of the proposed strategy leads to the best-operating cost-saving and operational GHG savings when compared to other published approaches. It has shown that other strategies are special (not always optimal) cases of the NPC strategy. Based on the extensive literature review, it is found that it is exceptionally complicated to apply the previously proposed models of seasonal thermal energy storage in optimization software. Besides, the high computational time is required to obtain an optimum size and operation of storage from an optimization software. This thesis also proposes a new flexible semi-analytical, semi-numerical methodology to model the heat transfer process of the borehole thermal energy storage to solve the above challenges. The model increases the flexibility of the storage operation since the model can control the process of the storage by also deciding the appropriate storage zone for charging and discharging. / Thesis / Doctor of Engineering (DEng)