Suomen kasvihuonekaasupäästöt Kioton pöytäkirjan ensimmäisen sopimuskauden lopussa – kokonaistilanne ja vähentämistoimenpiteet

Tämä diplomityö on läpileikkaus kasvihuonekaasupäästöistä sekä niitä koskevista vähennystoimenpiteistä Suomessa Kioton pöytäkirjan ensimmäisen sopimuskauden lopussa. Työ on toteutettu kirjallisuustutkimuksena ja siihen on käytetty painettuja sekä sähköisiä lähteitä. Huoli ilmastonmuutoksesta on saanut aikaan sen, että kasvihuonekaasupäästöjä rajoitetaan tänä päivänä kansainvälisillä sopimuksilla. Vaikka kaikki suuretkaan päästäjämaat eivät ole sopimuksia ratifioineet, ovat EU-maat Suomi mukaan lukien sitoutuneet YK:n ilmastonmuutosta koskevaan puitesopimukseen ja sen noudattamiseen. Puitesopimusta tarkentavassa Kioton pöytäkirjassa EU sitoutui vähentämään kuuden eri kasvihuonekaasun kokonaispäästöjä yhteensä 8 prosenttia ajanjaksolla 2008–2012 vuoteen 1990 verrattuna. Kasvihuonekaasut, joita rajoitukset koskivat, olivat hiilidioksidi, metaani, dityppioksidi, fluorihiilivedyt, perfluorihiilivedyt ja rikkiheksafluoridi. EU:n sisäisessä taakanjaossa Suomen tavoite oli pitää päästöt vertailuvuoden 1990 tasossa ja Suomi alitti tämän noin viidellä prosentilla. Vuoden 2012 jälkeen Suomen kasvihuonekaasupäästöjen vähennystavoite on kiristynyt. Vuosille 2013–2020 Suomen tavoite on vähentää kasvihuonekaasupäästöjä 20 prosenttia alle perusvuoden 1990 tason. Työssä tutustutaan myös keinoihin, joilla aiempien ja tulevien päästöjenvähennystavoitteiden saavuttaminen on mahdollista. Näitä keinoja on mm. erilaisten biopolttoaineiden sekoittaminen fossiilisten polttoaineiden sekaan, energiatehokkuuden parantaminen ja biokaasun käytön lisääminen. Lisäksi työssä käsitellään eräitä merkityksellisiä käsitteitä, kuten EU:n päästökauppajärjestelmä ja hiilidioksidin talteenotto ja varastointi.

On Distributed Storage Codes

Distributed storage systems are studied. The interest in such system has become relatively wide due to the increasing amount of information needed to be stored in data centers or different kinds of cloud systems. There are many kinds of solutions for storing the information into distributed devices regarding the needs of the system designer. This thesis studies the questions of designing such storage systems and also fundamental limits of such systems. Namely, the subjects of interest of this thesis include heterogeneous distributed storage systems, distributed storage systems with the exact repair property, and locally repairable codes. For distributed storage systems with either functional or exact repair, capacity results are proved. In the case of locally repairable codes, the minimum distance is studied. Constructions for exact-repairing codes between minimum bandwidth regeneration (MBR) and minimum storage regeneration (MSR) points are given. These codes exceed the time-sharing line of the extremal points in many cases. Other properties of exact-regenerating codes are also studied. For the heterogeneous setup, the main result is that the capacity of such systems is always smaller than or equal to the capacity of a homogeneous system with symmetric repair with average node size and average repair bandwidth. A randomized construction for a locally repairable code with good minimum distance is given. It is shown that a random linear code of certain natural type has a good minimum distance with high probability. Other properties of locally repairable codes are also studied.

Unequal Teeth Widths for Torque Ripple Reduction in Permanent Magnet Synchronous Machines With Fractional-Slot Non-Overlapping Windings

Permanent magnet synchronous machines with fractional-slot non-overlapping windings (FSPMSM), also known as tooth-coil winding permanent magnet synchronous machines (TCW PMSM), have been under intensive research during the latest decade. There are many optimization routines explained and implemented in the literature in order to improve the characteristics of this machine type. This paper introduces a new technique for torque ripple minimization in TCW PMSM. The source of torque harmonics is also described. The low order torque harmonics can be harmful for a variety of applications, such as direct drive wind generators, direct drive light vehicle electrical motors, and for some high precision servo applications. The reduction of the torque ripple harmonics with the lowest orders (6th and 12th) is realized by machine geometry optimization technique using finite element analysis (FEA). The presented optimization technique includes the stator geometry adjustment in TCW PMSMs with rotor surface permanent magnets and with rotor embedded permanent magnets. Influence of the permanent magnet skewing on the torque ripple reduction and cogging torque elimination was also investigated. It was implemented separately and together with the stator optimization technique. As a result, the reduction of some torque ripple harmonics was attained.

Integrated energy storage tank for large scale power-to-gas applications

The global interest towards renewable energy production such as wind and solar energy is increasing, which in turn calls for new energy storage concepts due to the larger share of intermittent energy production. Power-to-gas solutions can be utilized to convert surplus electricity to chemical energy which can be stored for extended periods of time. The energy storage concept explored in this thesis is an integrated energy storage tank connected to an oxy-fuel combustion plant. Using this approach, flue gases from the plant could be fed directly into the storage tank and later converted into synthetic natural gas by utilizing electrolysis-methanation route. This work utilizes computational fluid dynamics to model the desublimation of carbon dioxide inside a storage tank containing cryogenic liquid, such as liquefied natural gas. Numerical modelling enables the evaluation of the transient flow patterns caused by the desublimation, as well as general fluid behaviour inside the tank. Based on simulations the stability of the cryogenic storage and the magnitude of the key parameters can be evaluated.

Cost Reduction of Permanent Magnet Synchronous Machines

Electrical machine drives are the most electrical energy-consuming systems worldwide. The largest proportion of drives is found in industrial applications. There are, however many other applications that are also based on the use of electrical machines, because they have a relatively high efficiency, a low noise level, and do not produce local pollution. Electrical machines can be classified into several categories. One of the most commonly used electrical machine types (especially in the industry) is induction motors, also known as asynchronous machines. They have a mature production process and a robust rotor construction. However, in the world pursuing higher energy efficiency with reasonable investments not every application receives the advantage of using this type of motor drives. The main drawback of induction motors is the fact that they need slipcaused and thus loss-generating current in the rotor, and additional stator current for magnetic field production along with the torque-producing current. This can reduce the electric motor drive efficiency, especially in low-speed, low-power applications. Often, when high torque density is required together with low losses, it is desirable to apply permanent magnet technology, because in this case there is no need to use current to produce the basic excitation of the machine. This promotes the effectiveness of copper use in the stator, and further, there is no rotor current in these machines. Again, if permanent magnets with a high remanent flux density are used, the air gap flux density can be higher than in conventional induction motors. These advantages have raised the popularity of PMSMs in some challenging applications, such as hybrid electric vehicles (HEV), wind turbines, and home appliances. Usually, a correctly designed PMSM has a higher efficiency and consequently lower losses than its induction machine counterparts. Therefore, the use of these electrical machines reduces the energy consumption of the whole system to some extent, which can provide good motivation to apply permanent magnet technology to electrical machines. However, the cost of high performance rare earth permanent magnets in these machines may not be affordable in many industrial applications, because the tight competition between the manufacturers dictates the rules of low-cost and highly robust solutions, where asynchronous machines seem to be more feasible at the moment. Two main electromagnetic components of an electrical machine are the stator and the rotor. In the case of a conventional radial flux PMSM, the stator contains magnetic circuit lamination and stator winding, and the rotor consists of rotor steel (laminated or solid) and permanent magnets. The lamination itself does not significantly influence the total cost of the machine, even though it can considerably increase the construction complexity, as it requires a special assembly arrangement. However, thin metal sheet processing methods are very effective and economically feasible. Therefore, the cost of the machine is mainly affected by the stator winding and the permanent magnets. The work proposed in this doctoral dissertation comprises a description and analysis of two approaches of PMSM cost reduction: one on the rotor side and the other on the stator side. The first approach on the rotor side includes the use of low-cost and abundant ferrite magnets together with a tooth-coil winding topology and an outer rotor construction. The second approach on the stator side exploits the use of a modular stator structure instead of a monolithic one. PMSMs with the proposed structures were thoroughly analysed by finite element method based tools (FEM). It was found out that by implementing the described principles, some favourable characteristics of the machine (mainly concerning the machine size) will inevitable be compromised. However, the main target of the proposed approaches is not to compete with conventional rare earth PMSMs, but to reduce the price at which they can be implemented in industrial applications, keeping their dimensions at the same level or lower than those of a typical electrical machine used in the industry at the moment. The measurement results of the prototypes show that the main performance characteristics of these machines are at an acceptable level. It is shown that with certain specific actions it is possible to achieve a desirable efficiency level of the machine with the proposed cost reduction methods.

CloudSimDisk: Energy-Aware Storage Simulation in CloudSim

Cloud Computing paradigm is continually evolving, and with it, the size and the complexity of its infrastructure. Assessing the performance of a Cloud environment is an essential but strenuous task. Modeling and simulation tools have proved their usefulness and powerfulness to deal with this issue. This master thesis work contributes to the development of the widely used cloud simulator CloudSim and proposes CloudSimDisk, a module for modeling and simulation of energy-aware storage in CloudSim. As a starting point, a review of Cloud simulators has been conducted and hard disk drive technology has been studied in detail. Furthermore, CloudSim has been identified as the most popular and sophisticated discrete event Cloud simulator. Thus, CloudSimDisk module has been developed as an extension of CloudSim v3.0.3. The source code has been published for the research community. The simulation results proved to be in accordance with the analytic models, and the scalability of the module has been presented for further development.

Variance reduction properties of dynamic hedging models - empirical evidence from BRICS countries

This Master’s Thesis analyses the effectiveness of different hedging models on BRICS (Brazil, Russia, India, China, and South Africa) countries. Hedging performance is examined by comparing two different dynamic hedging models to conventional OLS regression based model. The dynamic hedging models being employed are Constant Conditional Correlation (CCC) GARCH(1,1) and Dynamic Conditional Correlation (DCC) GARCH(1,1) with Student’s t-distribution. In order to capture the period of both Great Moderation and the latest financial crisis, the sample period extends from 2003 to 2014. To determine whether dynamic models outperform the conventional one, the reduction of portfolio variance for in-sample data with contemporaneous hedge ratios is first determined and then the holding period of the portfolios is extended to one and two days. In addition, the accuracy of hedge ratio forecasts is examined on the basis of out-of-sample variance reduction. The results are mixed and suggest that dynamic hedging models may not provide enough benefits to justify harder estimation and daily portfolio adjustment. In this sense, the results are consistent with the existing literature.

Liiketoimintayksikön materiaalihallinnan nykytila ja sen tehostaminen materiaalien suoratoimituksilla

Tutkimuksen tarkoituksena on tutkia kansainvälisesti toimivan konserniyrityksen yhden liiketoimintayksikön materiaalinhallinnan ja siihen liittyvien toimintojen nykytilaa. Lisäksi tutkimuksessa selvitetään, miten materiaalinhallintaa varastoinnin osalta voidaan kehittää suoratoimitusmallin periaatetta hyödyntäen ja mitä säästöpotentiaaleja tämän kaltaiseen malliin liittyy kohdeorganisaation toimintaympäristö huomioiden. Tutkimuksen teoriaosion lähdeaineisto koostuu materiaalinhallinnan perusteosten lisäksi tieteellisistä artikkelijulkaisuista. Käytännönosuuden aineisto pohjautuu kohdeorganisaatiossa käytyihin keskusteluihin, tuotannonohjausjärjestelmästä saatuun tietoon ja omiin havaintoihin. Nykytilanteen analyysissä selvisi, että kohdeorganisaation varastointiin liittyy tehostamispotentiaalia erityisesti tila-, käsittely, ja työkustannusten osalta. Kohdeorganisaation varastoinnin tehostamista tutkittiin suoratoimitusmallin avulla. Suoratoimitusmallissa materiaalit eivät kierrä kohdeorganisaation pitämän välivaraston kautta, vaan ne toimitetaan toimittajan tiloista suoraan tuotannon välittömään tarpeeseen. Mallin avulla voidaan jakaa toimittajien kanssa sellaisia resursseja, joita molempien toiminta vaatii ja täten vapauttaa nykyistä varastointitilaa ja keventää sisäisen logistiikan kuormaa. Suoratoimitusmallin liittyvien hyötyjen kannalta on oleellista, että malliin valitaan sellaiset materiaalit, jotka sisältävät eniten potentiaalia niin säästö- kuin soveltuvuusnäkökulmasta. Valittujen kriteerien avulla kohdeorganisaation hankkimista materiaaleista löydettiin joukko materiaaleja, joiden avulla pystyttiin osoittamaan, että suoratoimitusmallin avulla on mahdollista saavuttaa kustannussäätöjä varastoinnin osalta.

Performance Degradation Modelling and Techno-Economic Analysis of Lithium-Ion Battery Energy Storage Systems

Transmission system operators and distribution system operators are experiencing new challenges in terms of reliability, power quality, and cost efficiency. Although the potential of energy storages to face those challenges is recognized, the economic implications are still obscure, which introduce the risk into the business models. This thesis aims to investigate the technical and economic value indicators of lithium-ion battery energy storage systems (BESS) in grid-scale applications. In order to do that, a comprehensive performance lithium-ion BESS model with degradation effects estimation is developed. The model development process implies literature review on lifetime modelling, use, and modification of previous study progress, building the additional system parts and integrating it into a complete tool. The constructed model is capable of describing the dynamic behavior of the BESS voltage, state of charge, temperature and capacity loss. Five control strategies for BESS unit providing primary frequency regulation are implemented, in addition to the model. The questions related to BESS dimensioning and the end of life (EoL) criterion are addressed. Simulations are performed with one-month real frequency data acquired from Fingrid. The lifetime and cost-benefit analysis of the simulation results allow to compare and determine the preferable control strategy. Finally, the study performs the sensitivity analysis of economic profitability with variable size, EoL and system price. The research reports that BESS can be profitable in certain cases and presents the recommendations.