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  • Johnson S, Rejish Lal
    KTH, School of Industrial Engineering and Management (ITM).
    Thermal gas radiation modelling for CFD simulation of rocket thrust chamber2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Methane and oxygen are a promising propellant combination in future rocket propulsion engines mainly due to its advantages like reusability and cost reduction. In order to have a comprehensive understanding of this propellant combination extensive research work is being done. Especially, for reusable rocket engines the thermal calculations become vital as an effective and efficient cooling system is crucial for extending the engine life. The design of cooling channels may significantly be influenced by radiation. Within the framework of this thesis, the gas radiation heat transfer is modelled for CFD simulation of rocket thrust chambers and analysed for the ūĚź∂ūĚźĽ4/ūĚĎā2 fuel combination. The radiation is modelled within ArianeGroup‚Äôs in-house spray combustion CFD tool - Rocflam3, which is used to carry out the simulations.

    Radiation properties can have strong influence for certain chemical compositions, especially ūĚź∂ūĚĎā2 and ūĚźĽ2ūĚĎā which are the products of the ūĚź∂ūĚźĽ4 and ūĚĎā2 combustion. A simplified gas radiation transport equation is implemented along with various spectral models which compute the gas emissivity for higher temperature. Also, Rocflam-II code which has an existing gas radiation model is used to compare and validate the simplified model. Finally the combination of the convective and radiative heat transfer values are compared to the experimental test data. In contrast to the previously existing emissivity models with a certain temperature limit, the model used here enables the inclusion for the total emissivity of ūĚź∂ūĚĎā2 and ūĚźĽ2ūĚĎā for temperatures up to 3400 K and hence more appropriate for hydrocarbon combustion in space propulsion systems.

    It turns out that the gas radiation is responsible for 2-4% of the total heat flux for a ūĚź∂ūĚźĽ4/ūĚĎā2 combustion chamber with maximum integrated temperature of 2700 K. The influence of gas radiation would be greater than 4% respective of the integrated temperature. Gas radiation heat flux effects are higher in stream-tube combustion zone compared to the other sections of the thrust chamber. The individual contribution of radiative heat flux by ūĚź∂ūĚĎā2 was noted to be 1.5-2 times higher than that to ūĚźĽ2ūĚĎā. It was shown that the analytically derived simplified expression for gas radiation along with the various spectral models had reasonable approximation of the measured radiation. The estimated radiation was correct to the measured radiation from the Rocflam-II model for a temperature range of 400-3400 K.

  • Wahlgren, Lars Fredrik
    KTH, School of Industrial Engineering and Management (ITM).
    Evaluation of CFD Methods for Prediction of Total Temperature and Total Pressure Distribution in Gas Turbines2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work was performed as a collaboration between the Royal Institute of Technology in Stockholm and Siemens Industrial Turbomachinery in Finspång. It was undertaken with the purpose of investigating the use of CFD methods in ANSYS CFX to predict flow mixing in gas turbines.

    The results were evaluated against experimental data gathered as part of an international collaboration; The FACTOR project. The experimental data investigated were total temperature and total pressure at nozzle guide vane inlet and outlet.

    The results thus focus mainly on nozzle guide vane inlet and outlet due to the nature of the available experimental data.

    The distribution of these parameters was also investigated in the NGV flow channel and on the vane surface, but it is appreciated that any conclusions drawn from these results are speculative in nature due to the lack of experimental data. Any conclusions drawn must be placed in perspective of the evaluation of NGV inlet and outlet, for which experimental data is available.

    The focus was on the mixing of the total temperature and total pressure in a nozzle guide vane connected to a combustion chamber simulator.

    The methods investigated were RANS-SST, SBES and LES-WALE. The main conclusions are that the inclusion of a combustion chamber mesh and thus simulating the CC flow increases the accuracy of the nozzle guide vane results for RANS-SST simulations. It is also observed that in general the SBES and LES-WALE method yield highly similar results under the investigated circumstances, and that both these methods show a general improvement over the RANS-SST method.

  • Pettersson, Marcus
    KTH, School of Industrial Engineering and Management (ITM).
    Cooling Potential of Methane in Rocket Nozzle Cooling Channels: A Conjugate Heat Transfer Analysis2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of hydrocarbons as fuel in rocket propulsion has been of great interest to the aerospace industry in recent years. Specifically, natural gas with a high content of methane has taken the interest of several actors, among them Sweden-based GKN Aerospace who in collaboration with KTH Royal Institute of Technology have started the MERiT project. In this project, the potential of methane as a fuel is explored through conjugate heat transfer analysis of a cooling channel geometry on a test rig. The goal is partly to find what the cooling potential of the methane is, and partly to determine the risks of thermal cracking occurring in the cooling channel.

    This report aims to provide a CFD analysis of the behavior of a test rig developed in earlier stages of the project. The analysis is to be used to provide design points that real experiments can be based upon. Studied behaviors include limitations regarding overheating, choke in the cooling channel and efficiency of the rig. In addition to this, the fluid temperature is studied in order to provide an estimate of which design points provide the highest potential risk of thermal cracking. In experiments, this potential risk is to be evaluated and explored in order to judge the viability of methane as a fuel.

    From this thesis a database of design points has been built regarding two potential channel geometries with different alloy materials. The post process and gathering of data are designed in such a way that specific behaviors can be monitored depending on a specific input. Inputs include mass flow, heat flux, inlet temperature and outlet pressure of the test rig. These were parametrized such that 243 specific design points could be examined for each channel geometry. Concluding this thesis, it was found that 131 of the cases examined for the first channel geometry were within the realm of being useful, and that a few cases fall within the realm of being at risk for coking. The risk for choke in the cooling channel is apparent at high mass flows and low pressures. The efficiency is heavily tied to heat flux and inlet temperature but shifts to be more dependent on Reynold’s number when cases with unintended behavior are filtered out.

  • Andersson, Jacob
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Danielsson, Fredrik
    KTH, School of Industrial Engineering and Management (ITM).
    A Study of Air Suspended AWD Trucks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Currently, Scania is not offering full air suspended AWD trucks, which it seems to be a demand for. This study acts as a first step to fulfill this demand. Including, a benchmarking of what competitors offer as well as an investigation and an evaluation of Scania’s current suspension system. Moreover, a requirement specification and a concept generation for a front air suspension system on AWD trucks have been presented. Eight concept were generated, where two were chosen for further study of design, force analysis and roll gradient analysis. It was concluded that there is a market for this configuration, however, implementing it would require extensive design work.

  • Ruan, Tianqi
    KTH, School of Industrial Engineering and Management (ITM).
    Techno-Economic Analysis of an Innovative Purely Solar Driven Combined Cycle System based on Packed Bed TES Technology2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With increasing awareness of environmental issues and worldwide requirements for sustainable development, renewable energy technologies with lower environmental impact, especially those having abundant resources like wind and solar energy, attract more attention. Concentrating Solar Power (CSP) is one of the most promising solar energy technologies. Indeed, thermal energy storage (TES) units could be integrated into CSP plants, enhancing their flexibility and capacity factor. However, tower based CSP plants still remain cost intensive.

    This study evaluates the performance of a 55MWe combined-cycle CSP plant with rock-bed TES located in Sevilla, Spain. Sensitivity analysis has been performed to assess the influence of critical parameters. Furthermore, in order to decrease the costs with increasing efficiency, improved CSP plant schemes have been proposed.

    In the study, EES, SAM and TRNSYS are used to design and simulate the model from technological perspective, then the capital and operational costs are calculated in MATLAB. For one-year simulation of the designed case, the performance of the plant is determined by the trade-off among several conflicting factors. The study focuses on three key indicators to measure the performance- levelized costs of electricity (LCoE), capital expenditure (CAPEX) and efficiency factor (UF). As long as CAPEX is within the acceptable range, LCoE would be the most concerned one-as low as possible, then followed by UF. Compared to conventional CCGT plant, the proposed combined-cycle tower-based CSP plant, with efficiency of 0.49 and LCoE of 196USD/MWe, enables efficiency improvements, while both CAPEX and LCoE are higher. On the other hand, it has to be noticed that CCGT relies on fuel (natural gas) price, which means higher risks and operational expenditure (OPEX). A sensitivity study is involved varying gas turbine expansion ratio (to vary its outlet temperature and therefore supply power for the bottoming Rankine cycle), size of TES and solar multiple (SM). It can be found that same LCoE and UF could be achieved with lower CAPEX by setting appropriate parameters.

    The study also introduces two improved CSP plant schemes with sensitivity study. To some extent, the LCoE decreases due to increasing power output and the efficiency of the system simultaneously increases.

  • Siddique, Muhammad Bilal
    KTH, School of Industrial Engineering and Management (ITM).
    Techno-economic analysis of mobile battery storage systems to utilize curtailed wind energy in Germany for off-grid applications2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increasing share of renewable energy especially wind energy leads to increased share of unpredictable and varying energy into the grid. This leads to congestion in the grid which ultimately results in wind curtailment. In Germany in 2015 alone more than 4000 GWh of wind energy was curtailed. On the other hand, off grid energy requirements for event industry especially concerts and festivals, rely heavily on diesel generators to fulfill their power requirements. This thesis investigates a unique use case for the mobile storage application. The batteries are used to utilize the curtailed wind energy for off-grid applications like festivals and concerts in Germany. The batteries are charged at the wind farm during the duration of curtailment and once they are fully charged, the batteries are transported to the location of concert or an event to provide clean energy. The batteries or storage system used for this case have a capacity of 1.5 MWh and the whole system is constructed in a standard shipping container to allow convenient transportation.

    According to the findings of this study, the proposed use case can lead to a significant CO2 emission reduction, a single storage system could save up to about 8.4 million kg of CO2, at the events and festivals. Furthermore, it could help in renewable energy integration by providing clean wind energy, that is otherwise curtailed, to festivals and concerts. This study identifies a wind farm with most curtailed energy in Germany with total curtailment duration accounting for about 32% of the time in the year 2017. The technical model, simulated in MATALB/Simulink, successfully charged the battery storage system without any bottleneck. The levelized cost of storage was found to be in comparison with the levelized cost of diesel generators. A single storage system has an ability save up to 8.4 million kg of CO2 emissions. The study further proposes policy suggestions to promote such innovative use case.

  • Rosso, Stefano
    KTH, School of Industrial Engineering and Management (ITM).
    Power Plant Operation Optimization Economic dispatch of combined cycle power plants2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As electricity production from renewable sources increases, higher flexibility is required by fossil fuel generation to cope with the inherent fluctuations of solar and wind power. This results in shorter operating cycles and steeper ramps for the turbines, and more uncertainty for the operators.

    This thesis work applies mathematical optimization and statistical learning to improve the economic dispatch of a combined cycle power plant composed by two separate blocks of two gas turbines and one steam turbine. The goal is to minimize the input fuel to the gas turbines while respecting a series of constraints related to the demand the plant faces, power generation limits etc. This is achieved through the creation of a mathematical model of the plant that regulates how the plant can operate. The model is then optimized to reduce fuel consumption at a minimum.

    Machine learning techniques have been applied to sensor data from the plant itself to realistically simulate the behavior of the turbines. Input-Output curves have been obtained for power and exhaust heat generation of all the turbines using ordinary least squares on monthly data with a ten minutes sampling rate. The model is cross-validated and proven statistically valid.

    The optimization problem is formulated through generalized disjunctive programming in the form of a mixed-integer linear problem (MILP) and solved using a branch-and-bound algorithm. The output of the model is a one-week dispatch, in fifteen minutes intervals, carried out for two months in total.

    Lower fuel consumption is achieved using the optimization model, with a weekly reduction of fuel consumed in the range of 2-4%. A sensitivity analysis and a correlation matrix are used to highlights the demand and the maximum available capacity as critical parameters. Results show that the most efficient machines (alternatively, the ones with highest available capacity) should be operated at maximum load while still striving for an efficient utilization of the exhaust gas.

  • Budianto, Richard
    KTH, School of Industrial Engineering and Management (ITM).
    A cost-optimal and geospatial analysis for the power system of Sierra Leone2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In 2014, the electricity access in Sierra Leone was almost 13.1%, consisting of 42% in urban areas and 1% in rural areas. The high transmission and distribution losses in the national grid, the insufficient generation capacity, and regulatory constraints are also some of the country¬īs challenges in the power sector (SEforALL Africa Hub, 2018). Nevertheless, the government of Sierra Leone has set a target to increase the electrification rate to 92% in 2030 (SEforALL Africa Hub, 2018). This target could be achieved by exploiting the abundant sources of renewable energy in such as hydro and solar.

    The objective of this study is to analyze the investments in the power sector of Sierra Leone in order to cover the country¬īs future electricity needs considering national targets (electrification rate) and different tiers of electricity in the residential sector. The modelling tools, OnSSET,spatial electrification planning tool and OSeMOSYS, cost optimization for medium to long-run integrated assessment and energy planning tool are used for this thesis project.

    In order to achieve future electricity target, the modelling period of this study has been set to 2015- 2065. Under this study, three scenarios are analyzed, the reference, medium electricity demand, and high electricity demand for the period 2015-2065. In 2015, the consumption level was 578 kWh/household/year for the urban population and 73 kWh/household/ year for the rural population. The reference scenario considers Tier 3 (Global Tracking Framework, 2015) on electricity consumption for urban population and Tier 2 (Global Tracking Framework, 2015) for the rural population in 2065. The medium electricity demand scenario assumes slightly higher energy consumption (Tier 4 (Global Tracking Framework, 2015) for urban population and Tier 3 (Global Tracking Framework, 2015) for rural population) in 2065. Lastly, the high electricity demand scenario assumes the highest electricity demand (Tier 5 (Global Tracking Framework, 2015) for urban population and Tier 4 (Global Tracking Framework, 2015) for rural population) in 2065.

    This study shows that for Sierra Leone, in order to cover its electricity needs in the future as well as to be fully electrified, its power generation will mainly be based on hydro. In the Reference scenario, where both OnSSET and OSeMOSYS analysis were used, it is suggested that 28% of the total electricity produced is to be generated by solar PV and 60% by hydropower plant. This is due to the fact that OnSSET, as a spatial analysis tool, also takes into consideration the distance between available resource and demand, on top of resource availability. Meanwhile, in the medium and high electricity demand scenarios, where only OSeMOSYS analysis was conducted, hydropower plant shows a more dominant contribution than the reference scenario. Around 68% of total electricity produced for medium electricity demand scenario is from hydropower plant. In the high electricity demand scenario, besides high electricity production from hydro (79.5% of total electricity produced), production from other technology such as HFO and solar PV is more evenly spread, especially in 2065.

    Overall, it can still be deduced that hydro power plant is the most promising option for electricity generation in all scenarios. This is attributed mostly to its abundance as well as low production costs, such that even when the distance is considered, it is still reasonably more attractive than other options available.

  • Rama Curiel, Jos√© Adrian
    KTH, School of Industrial Engineering and Management (ITM).
    Analysis of potential impact of direct load control of AC units in the Indian State of Karnataka2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Demand Side Management (DSM) is a term coined to describe the control of demand to optimize energy usage in a way beneficial to both users and utilities. There are different technologies and policies designed for DSM, and one of them is Direct Load Control (DLC) which refers to a utility directly controlling demand. In this thesis, an analysis of DLC for air conditioning units during summer in the Indian state of Karnataka is carried out. A new control mechanism is proposed, based on the local generation capacity, which seems to reduce until the monsoon season arrives, as the lack of rain reduces water levels in hydro power plants. The direct load control of ACs using this mechanism allows for 0.88% energy savings in a state where only around 5% of all households seem to have AC units and electricity is available for only 37% of the population. The mentioned savings could have significant economic impacts for both users and utilities, reduce the fossil-based energy consumption and/or improve issues such as blackouts and the lack of capacity to cover peak loads. Continuous improvements in both energy access and the economic conditions of the state will lead to a larger number of AC’s installed, meaning that a mechanism that reduces AC consumption could be of great utility for all stakeholders of the electricity sector.

  • Public defence: 2019-12-18 10:00 Sal Sefstr√∂m, Stockholm
    Jarnerud, Tova
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Utilization of recovered lime-containing materials from pulp and paper industries as slag formers in stainless steel production2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In recent years, major efforts have been made to develop a more circular economy. The desire to reuse, remanufacture and recycle materials are important for the development towards a sustainable society. An extended lifespan of materials helps to reduce the amount of waste kept in landfills, as well as to reduce the extraction of natural resources. Pulp and paper and steel industries are two of the largest export industrial sectors in Sweden. It is well known that the pulp and paper industries also generates large amounts of organic and inorganic wastes, of which a significant part is kept in landfills. Year by year deposit of wastes in landfills is becoming more difficult to handle and expensive due to stronger regulations and requirements regarding the environment. During Electric Arc Furnace (EAF) and Argon Oxygen Decarburization (AOD) stainless steelmaking operations, burnt lime (primary lime) is charged together with other slag forming materials in the furnace or converter to attain a specific basicity of the slag and to achieve purification from unwanted elements by chemical reactions in the steel.

    However, a number of CaO-containing wastes from pulp/paper mills can be used as slag formers in steelmaking processes to replace the currently used burnt natural lime, since the use of this primary lime does not conform with the closing the loop idea that is being prioritized in modern society. This thesis presents results from preliminary experiments for examining the replacement of primary lime with secondary lime from pulp and paper production waste as slag formers in EAF and AOD converters. The obtained results showed a possibility of using up to 30% CaO from secondary lime as a replacement for primary lime in the EAF. Furthermore, the amount of ferrosilicon alloys additions can be decreased by up to 3kg/ton of steel. For the AOD process the use of secondary lime doesn¬īt have any negative effects on the decarburization process and reduction process. Furthermore, it has similar desulphurization functions as the primary lime. However, the phosphorus content in the metal was slightly increased. Thus, the replacement ratio of secondary lime will be limited by the acceptable phosphorus level in the final steel due to higher phosphorus content in wastes from pulp and paper mills compared to that in primary lime. Moreover, it was revealed during this study that slags from AOD converters can be used as binding agents for briquetting of these secondary lime materials. These results shows that waste/by products from two major industries can be used to make metallurgical briquettes, uniting two major industrial sectors in a circular symbiosis towards a more sustainable future.

  • Ollas, Fredrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Ernir Vi√įarsson, Gestur
    KTH, School of Industrial Engineering and Management (ITM).
    Proposed Design and Feasibility Study of a Hybrid-Electric Propulsion System for a Ten Passenger Aircraft2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aims to propose a hybridized version of a propulsion system for a 10-passenger aircraft and compare it to a conventional (reference) aircraft which uses a fossil fuelled turbofan for propulsion. The hybridized powertrain includes a fossil fuelled gas turbine, which is only used for producing electricity, coupled in a series configuration with a battery storage, that provide power to two electrically ducted fans.

    The comparison mainly aims towards total energy consumption and carbon dioxide emissions; hence, these are aimed to be reduced in the hybridized solution. The aircrafts are compared when flying the same pre-defined route that is a 900 km long distance, cruising at an altitude of 7500 m at 150 m/s. Rate of climb, climb speed and descent angle are optimized, with regards to energy demand. The hybridized propulsion system is evaluated in three different scenarios, that is: 2020, Near Future- and Advanced Future scenario, which contain different component properties that address different future predictions.

    An experiment is conducted with a small scale electrical ducted fan, operating in a wind tunnel, to measure different quantities such as power and thrust. These results are then scaled up and used as design parameters for a proposed fan design that is of sufficient size to propel the hybridized aircraft.

    The results show that the hybridized concept, at design conditions, proves feasible in all scenarios. The mass of the aircraft increases as the hybridized system is introduced, but nevertheless the fuel consumption decreases where the reduction depends highly on energy density of the batteries.

  • Dominik Benjamin, Philipp
    KTH, School of Industrial Engineering and Management (ITM).
    Decarbonization Pathways for the German Chemical and Steel Industry: Integrated Scenario-Based Technology Roadmaps2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Currently Germany is failing to reach its set emission targets. To achieve the envisioned carbon neutrality until 2050 fundamental changes will have to be implemented in all productive and non-productive sectors in the coming decades. Especially the transformation of the industry is of interest, as Germany’s economy relies heavily on the large industrial sector. This paper focusses on the transition of the two largest industrial sectors, the chemical and steel industry.

    The needed emission reduction in the industries will be mainly enabled by the implementation of innovative decarbonization technologies. Based on a thorough analysis of the developments of the technological and economic characteristics of the current production technologies and alternative decarbonized production technologies, this paper proposes detailed technology roadmaps for the decarbonization of the two industries until 2050.

    For developing the roadmaps two scenarios are defined: An economic potential scenario which aims at minimum cost of the transition and a technological potential scenario which aims at maximum emission reduction. In addition to the costs and emissions of the decarbonization technologies, the pathways of the industry transformation are defined by the reinvestment cycles of the existent production facilities and the market entry points of decarbonization technologies.

    The analysis of the modelled decarbonization pathways shows that the envisioned emission reduction target cannot be achieved based on the assessed decarbonization technologies, as either their remaining emissions are not low enough or their use is limited by external factors. The most promising technologies to achieve full decarbonization are based on hydrogen. The maximum achievable emission reduction is 84%, the economic potential scenario achieves only 75%.

    A sensitivity analysis of the emission reduction in the economic potential scenario against financial incentives shows a limited and sometimes even negative impact of external price reductions. The strongest positive effect is achieved by an increase of the price rise of CO2 price with a final price in 2050 in the range of 140 to 300 EUR/tCO2.

    Concerning the production cost the assessment reveals that, assuming a CO2 prices of 200 EUR/tCO2 in 2050, the production cost of most decarbonization technologies already drops below the cost of the current production technologies after 2030. This allows the general conclusion that the transition to a low carbon production will be profitable.

  • Oggioni, Niccol√≤
    KTH, School of Industrial Engineering and Management (ITM).
    Modelling of microgrid energy systems with concentrated solar power2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master’s thesis presents the work performed during a four-month long internship at Azelio AB in Gothenburg. Energy performance models for common energy technologies in microgrid energy systems were developed and validated. The investigated technologies are traditional and bifacial PV modules, wind turbines, Li-ion battery energy storage systems and diesel generators.

    Subsequently, they were utilised to simulate the energy supply of two remote communities in Queensland, Australia. Azelio’s CSP technology, which combines heliostats, thermal energy storage with phase change materials and Stirling engine, was introduced as well. By means of scenarios and key performance indicators, the possibility of disconnecting such towns from the local electricity distribution network was investigated. Both technical and economic aspects were analysed. This led to the conclusion that 10 MW CSP system would be sufficient to achieve grid independence if extra backup capacity, e.g. diesel generators, or demandside control strategies, are introduced.

    Sensitivity analysis performed on the possibility of dividing the CSP park into two clusters, the smaller one being subject to a power threshold, was investigated as well. In terms of economic feasibility, off-grid systems resulted more expensive than maintaining the grid connection.

  • Dahlstr√∂m, Pontus
    KTH, School of Industrial Engineering and Management (ITM).
    Potential of electrical building heating as thermal energy storage in Sweden2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this Master thesis is to investigate the potential of using electricity based building heating as thermal energy storage in Sweden and its applications. Building data and statistics along with literature were the basis for data collection and processing. The work was then carried out by selecting a thermal energy storage model to represent different building types that are equipped with electricity based heating systems. This aggregate thermal energy storage model was applied to the Swedish building stock, historical weather data and typical thermal comfort zones. The power and energy capacity of the thermal energy storage were studied and the model was used to evaluate Demand Response (DR) both as Price Based DR and Emergency DR. This thesis gives an approximation of the potential of both power and energy capacity which has not been clearly quantified in previous studies for thermal energy storage in buildings of Sweden. The thesis was carried out for the Department of Energy Technology (EGI) at the Division of Electric Power and Energy Systems (EPE) in collaboration with SWECO as part of the North European Energy Perspectives Project (NEPP).

  • Hoenes, Michael
    KTH, School of Industrial Engineering and Management (ITM).
    Potential of harvesting solar neutrinos to power electric cars2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Imminent penalties for excess emissions force the automotive industry to radically rethink how to power vehicles. Novel concepts are needed to facilitate these changes, which might be found by scouting patents of emerging and established companies. During their patent search, Daimler AG has come across a patent of the startup Neutrino Energy GmbH, which reveals a device designed to harvest solar neutrinos for electricity generation purposes. From here the question arises: Is it possible to harvest solar neutrinos to power electric consumers, such as cars? To answer this question, this study analyzes the solar neutrino flux on Earth’s surface and the state-of-the-art solar neutrino technology (including solar neutrino detectors used in research and the solar neutrino converter proposed by Neutrino Energy GmbH). The energy inherent to the solar neutrino flux is computed based on the solar neutrino spectrum found in literature. Solar neutrino detectors are analyzed on their ability to harvest solar neutrinos by consulting literature and by estimating their power output. In case of the graphene based converter by Neutrino Energy GmbH, the threshold energies of neutrino-graphene interactions are compared to the energies of incoming neutrinos to estimate an upper limit for the power output. Results from the analysis of the solar neutrino flux show that the energy inherent to solar neutrinos is too low to power an electric vehicle, even if it could be fully exploited. In fact, only a tiny fraction of the solar neutrino energy flux can be converted into electricity as neutrinos barely interact with matter. The analysis of the state-of-the-art solar neutrino research shows that detectors with a weight of several tonnes are constructed to capture signals from solar neutrinos. Still, the power output of such detectors is several orders of magnitude lower than the demand of an electric vehicle. Analyzing the concept developed by Neutrino Energy GmbH shows that only a small part of the solar neutrino flux can be harvested, insufficient to generate a significant amount of electricity. Hence, the conclusion is drawn, that solar neutrino conversion technology is no suitable candidate to enable sustainable mobility.

  • Pomares Bleda, Laura
    KTH, School of Industrial Engineering and Management (ITM).
    Analysis of load capacity in the low voltage network for different electricity load scenarios in Hammarby Sjöstad, Stockholm.2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sweden’s population is growing rapidly, especially in the southern areas like Stockholm, where the electricity consumption is higher. Therefore, more electricity will need to be transported from north to south, from where it is produced to where it is consumed. The current electric infrastructure, i.e. the transmission and distribution networks, will need to be able to handle this consumption increase. Moreover, transition through a more sustainable cities, notably in the transport sector with the increase in electric vehicle use and electrification of public transport sector, would rise even more the electricity needs. Increase in Stockholm’s electricity consumption is not possible due to capacity limitations and grid restrictions. The situation is already strained for the city and further electricity consumption would cause several contingences. The aim of this project is to analyze the impact of the increase in electricity demand due to population growth and the integration of electric vehicles on the low voltage network in one of Stockholm’s districts, Hammarby Sjöstad.

    In order to analyze it, six scenarios have been simulated, one base scenario representing today’s situation, four short-term scenarios for 2025 and one long-term scenario for 2040. Different EVs penetration levels are considered, as well as two different charging schedules, following an uncontrolled charging strategy.

    The results show that if today’s EV sales trend remains, the low voltage grid would be able to operate properly. However, if a massive increase of EV occurred, several problems would appear. For evening charging, at peak hour the load would increase around 20%, transformers of two of the four analyzed substations would be overloaded. Problems of power quality and line overloading would appear as well. For night charging, the peak gets displaced to night hours but the network situation is similar to the previous case. Even though a 100% of EV integration is not likely to happen by 2025, it could occur by 2040. Thus, actions on the grid would need to be done if the charging remains uncontrolled. By controlling the charging schedule or introducing load management, for instance by being able to manage the energy on the battery, the problem may be reduced.

  • Weinstein, Miles
    KTH, School of Industrial Engineering and Management (ITM).
    Future Scenarios for Energy Security and Sustainable Desalination in Jordan2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Jordan is one of the most water-scarce countries in the world and contains very limited reserves of traditional energy resources. In fact, the country is classified as extremely water scarce according to FAO, with a water availability of less than 100 m3 per person annually. Additionally, in 2017, 94% of total primary energy resources were imported. In parallel, the Kingdom’s population has more than doubled since 1997, due mainly to regional instability, putting a further strain on resources. Furthermore, climate change will only exacerbate water scarcity issues in the coming years.

    The objective of this thesis is to identify future scenarios for increased energy independence in Jordan and to examine the effect of desalination on the associated increase in water consumption for power generation. This intersection between water and energy resources is known as the Water-Energy nexus. Nexus planning is a holistic strategy that aims to create synergies between sectors, whereas traditional planning can in some cases put them at odds with each other (UNECE, 2015). The methodology is widely used for regional- or national-scale intersectoral planning and serves as the underlying motivation for this investigation.

    A model of Jordan’s power system on the national level was built using the Open Source Energy Modeling System (OSeMOSYS) with eight scenarios to 2050. OSeMOSYS uses linear programming for cost optimization in long-term planning. The program seeks to minimize cost based on the given data and constraints input by the modeler. Because the Jordanian Ministry of Energy and Mineral Resources (MEMR), has set a target for 40% of all energy to be supplied by domestic resources by 2025, several scenarios were created with varying domestic resource targets by that year. As a case study for desalination, The Red Sea-Dead Sea Water Conveyance Project (RSDSP) was used. The RSDSP is a massive desalination and hydropower project that, if constructed, will connect the Red Sea to the Dead Sea.

    The results of the scenarios have demonstrated that a 100% domestic power supply is, in fact, feasible by 2025. To achieve that, renewables, specifically wind and solar, will supply much of the added domestic resource capacity. At the same time, combined cycle power plants will also remain an integral part of the energy mix in order to provide dispatchable power production, as battery storage was found not to be cost effective. Large scale desalination, in the context of the RSDSP, was shown to be net freshwater positive in all scenarios. Thus, it is highly recommended that the project be constructed in order to provide a sustainable and reliable water source for the region. Together, the results of this project provide pathways for a sustainable and secure future for the energy and water sectors in Jordan.

  • Michaud, S√©bastien
    KTH, School of Industrial Engineering and Management (ITM).
    Techno-economic analysis of wind farm repowering strategies in France2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    French wind farms are aging. By 2025, the French Environment & Energy Management Agency estimates that 1 GW per year of operating wind turbines will reach their expected lifetime. The handling of wind turbines end of life is relatively new to wind farm owners, both technically and economically. New aspects to handle appear, such as dismantling, strategies of maintenance for the last years of living or again the repowered wind farm construction timing.

    This work aims at giving an overview of the volume France is going to have to handle in the coming years and how to handle it. The report gives insights for the main questions’ developers should ask themselves when they start thinking about the repowering of their assets. Those insights are based upon what is permitted by the current regulation, which will certainly evolve with the growing experience authorities will soon acquire.

    From those insights, different strategies will emerge, some more attractive from a technical point a view, but more difficult to set up in agreement with the regulation, common sense, and acceptance of local population. The goal will be to find the best balance between technical feasibility and aimed improvement.

    Those strategies can then be studied from an economical point of view to try to find the optimum rate of return. This profitability is not unique for a chosen technical scenario but can be optimized. An economic analysis tool will be set up. This tool can perform sensitivity analysis on a scenario, accepting as inputs the parameters that have the most influence on the results.

    Finally, a concrete application is given on an old and still operating wind farm. This shows one methodology that can be followed when thinking of repowering. There is, of course, multiple available solutions. The goal of this work is to provide developers with all the tools to perform a quick, efficient and accurate analysis of their repowering.

  • Menos-Aikateriniadis, Christoforos
    KTH, School of Industrial Engineering and Management (ITM).
    Methods to identify broken neutral fault in LV distribution grids by using existing smart meters infrastructure2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The vast majority of Swedish utility network customers for nearly a decade has been supported by Advanced Metering Management (AMM) systems, including smart meters. Vattenfall¬īs modern smart meters enable a new level of monitoring for LV networks and improved MV network supervision. Therefore, improving power quality, fault detection and outage management functionalities are just some of the areas that smart metering systems can contribute to. One of the typical faults in LV networks is when the neutral conductor is broken or loose at either the network or the load side of the meter. The situation of lost continuity of the neutral conductor may damage the connected load or create hazardous touch voltages at equipment body. Since there is a big potential to supervise LV networks with assistance of the end-customer smart meters, Vattenfall wants to take further advantage of such data. The value is to bring in event information from the smart meters in order to contribute to a better and more efficient monitoring of the LV and MV network. The goal of this project is to analyze the behavior of the LV grid under broken neutral fault conditions and propose effective methods (algorithms) to identify loose neutral situation based on end-customer meter readings (disturbance events).

    Based on previous literature review and studies conducted for broken neutral fault detection, phase to neutral voltages has been proved that can be a useful indicator to detect the fault, since there is a clear pattern during the fault. However, the voltages-based method is not always effective, such as during periods when the load is almost balanced among the three phases or when the load magnitude is not high enough. This is the reason why other electrical parameters could be useful as well to detect the fault, except from the phase to neutral voltages. This study adds a great value into the study of broken neutral fault in low voltage grids since no previous work has been found where dynamic load profiles are modelled and simulated.

    The broken neutral fault study has started with the creation of dynamic load profiles that has been used in MATLAB/SIMULINK to model inductive linear load with or without the integration of single-phase PV assets. Furthermore, non-linear load has been investigated during BN fault in a single-customer model, where three case studies with different percentages of nonlinear load integration into the system have been included. Later, a 7-customer low voltage rural grid has been modelled where not only broken neutral but also phase loss and short circuit faults have been modeled and simulated. 9 different locations for Broken Neutral and Phase Loss faults and 7 locations for Short Circuit fault, 4 seasons with different load profiles and 4 different PV integration combinations with single and three-phase assets were considered. It has been proved that the combination of different electrical parameters and not only phase to neutral voltages can improve significantly the detection of broken neutral fault, not only on the DSO side but also at the customer side, with the use of smart meter data.

    Last but not least, part of this study has been to use the data that have been produced from the simulations to train a machine learning model that can accurately detect broken neutral fault. For that reason, a Proof of Concept using different machine learning classification methods as well as neural networks have been trained and tested, based on large amount of data, has been proposed. Bagged decision trees have been found as the most accurate method.

    It is important to highlight that due to data confidentiality issues, specific values and thresholds that have been set in the algorithms that are currently used or proposed cannot be published.

  • Lindblad, Karl
    KTH, School of Industrial Engineering and Management (ITM).
    An economic feasibility study of hydrogen production by electrolysis in relation to offshore wind energy at Oxelösund2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the light of the world’s environmental concerns, every instance of society and in turn our industries, must take their responsibility in order to reach the goals set for ensuring a sustainable future. Standing globally for almost 10 % of all carbon emissions, the steel industry is a major actor in this problem. It is of great importance to change their processes if we are to reach our set goals.

    Swedish steel and energy industries have started working together to solve this in order to remain competitive in a future market which might value sustainability higher than ever. This is the background to the HYBRIT project which focuses on a new way of producing steel using hydrogen instead of coal, in a process called hydrogenation. Hydrogen can be produced in many ways, but electrolysis shows the greater sustainable potential and is therefore the focus for HYBRIT.

    The focus for this project is to examine the economic potential in hydrogen production by electrolysis in connection to an offshore wind energy farm. Various system sizes, types and designs were evaluated to understand how and if this could be considered economically feasible.

    During the study it became clear that these kinds of projects show great potential in order to reduce carbon emissions and an economic potential could be observed. Concerns arise when trying to reach the lowest hydrogen prices available on the market today but even these systems could be valued positive when applying low internal rates of returns.

    The main conclusion is that there is an economic potential for electrolysis systems in relation to offshore wind energy. What value this system might take, mostly comes down to investment costs, electricity prices and agreements between the concerned parties. In addition, green hydrogen could potentially be valued higher than market minimums and therefore increase the economic potential further. It can also be discussed that a deal stretching over multiple years could be considered stable and in turn increase value. Availability power production and hydrogen storage mostly affects the amount of green energy that is utilized in the process.

  • Rastan, Hamidreza
    KTH, School of Industrial Engineering and Management (ITM).
    Investigation of the heat transfer of enhanced additively manufactured minichannel heat exchangers2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mini-/microchannel components have received attention over the past few decades owing to their compactness and superior thermal performance. Microchannel heat sinks are typically manufactured through traditional manufacturing practices (milling and sawing, electrodischarge machining, and water jet cutting) by changing their components to work in microscale environments or microfabrication techniques (etching and lost wax molding), which have emerged from the semiconductor industry. An extrusion process is used to produce multiport minichannel-based heat exchangers (HXs). However, geometric manufacturing limitations can be considered as drawbacks for all of these techniques. For example, a complex out-of-plane geometry is extremely difficult to fabricate, if not impossible. Such imposed design constraints can be eliminated using additive manufacturing (AM), generally known as three-dimensional (3D) printing. AM is a new and growing technique that has received attention in recent years. The inherent design freedom that it provides to the designer can result in sophisticated geometries that are impossible to produce by traditional technologies and all for the redesign and optimization of existing models.

    The work presented in this thesis aims to investigate the thermal performance of enhanced minichannel HXs manufactured via metal 3D printing both numerically and experimentally. Rectangular winglet vortex generators (VGs) have been chosen as the thermal enhancement method embedded inside the flat tube. COMSOL Multiphysics, a commercial software package using a finite element method (FEM), has been used as a numerical tool. The influence of the geometric VG parameters on the heat transfer and flow friction characteristics was studied by solving a 3D conjugate heat transfer and laminar flow. The ranges of studied parameters utilized in simulation section were obtained from our previous interaction with various AM technologies including direct metal laser sintering (DMLS) and electron-beam melting (EBM).

    For the simulation setup, distilled water was chosen as the working fluid with temperaturedependent thermal properties. The minichannel HX was assumed to be made of AlSi10Mg with a hydraulic diameter of 2.86 mm. The minichannel was heated by a constant heat flux of 5 Wcm‚ąí2 , and the Reynolds number was varied from 230 to 950. A sensitivity analysis showed that the angle of attack, VG height, VG length, and longitudinal pitch have notable effects on the heat transfer and flow friction characteristics. In contrast, the VG thickness and the distance from the sidewalls do not have a significant influence on the HX performance over the studied range. On the basis of the simulation results, four different prototypes including a smooth channel as a reference were manufactured with AlSi10Mg via DMLS technology owing to the better surface roughness and greater design uniformity. A test rig was developed to test the prototypes. Owing to the experimental facility and working fluid (distilled water), the experiment was categorized as either a simultaneously developing flow or a hydrodynamically developed but thermally developing flow. The Reynolds number ranged from 175 to 1370, and the HX was tested with two different heat fluxes of 1.5 kWm‚ąí2 and 3 kWm‚ąí2 .

    The experimental results for the smooth channel were compared to widely accepted correlations in the literature. It was found that 79% of the experimental data were within a range of ¬Ī10% of the values from existing correlations developed for the thermal entry length. However, a formula developed for the simultaneously developing flow overpredicted the Nusselt number. Furthermore, the results for the enhanced channels showed that embedding VGs can considerably boost the thermal performance up to three times within the parameters of the printed parts. Finally, the thermal performance of the 3D-printed channel showed that AM is a promising solution for the development of minichannel HXs. The generation of 3D vortices caused by the presence of VGs ii can notably boost the thermal performance, thereby reducing the HX size for a given heat duty.

  • Parra Molina, Hector
    KTH, School of Industrial Engineering and Management (ITM).
    Design and analysis of a nZEB with IDA ICE.2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Recently, the environmental policy makers have realized that the building sector is the largest end-use sector with a significant percentage of the environmental load of human activities. What is more, according to official sources, it is necessary a reduction in the building sector of 88-91% of greenhouse gas emissions in order to achieve the goals established by the European Roadmap 2050. That is why laws such as the Directive 2010/31/EU are coming up. That directive says that all member states shall ensure that all new buildings are near zero energy buildings (nZEB) by December 31st, 2019. Therefore, the aim of this master thesis is the design of a nZEB in different climate zones around Spain. All near zero energy buildings designed meet the requirements established by the Spanish technical building code (CTE). In regard to the supply system, a facility is developed by means of IDA ICE consisting of a heat pump connected to an outdoor pool and a ground heat exchanger. The operation of the ground heat exchanger will depend on the temperature of the swimming pool. Finally, it is explained if the swimming pool can work as a heat source for each location studied.

  • Gas, Cl√©mentine
    KTH, School of Industrial Engineering and Management (ITM).
    Implementation of a Block Krylov Algorithm in Variational Data Assimilation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Numerical weather prediction relies on two major components: sophisticated atmospheric forecast models and equally important data assimilation algorithms. Data assimilation (DA) is the process used to produce the best estimate of the state of a model, using an Earth system numerical model and observations. This ‚Äúbest estimate‚ÄĚ will then be an accurate initial condition to the model.

    More and more applications of weather or weather-related forecasts (such as air quality) require estimates of the uncertainty in the forecasts, or even full probability distribution, to inform decision making. An estimate of the probability distribution of the analysis can be obtained by generating an ensemble of analysis. For each member of the ensemble, all inputs to the assimilation process are perturbed randomly according to their respective error statistics. Each data assimilation instance is an optimization problem and in the context of Ensemble Data Assimilation, many almost identical optimization problems are solved. So far, these problems have been solved independently of each other, using for example a Lanczos algorithm. However, it is possible to use information from all the members to construct a better approximation of the eigen-structure of the matrix at the heart of the optimization problem, and accelerate the convergence. The block-Lanczos algorithm is one of the block methods that exist to solve an Ensemble of Data Assimilation.

    This project consists in implementing the block Lanczos algorithm in the Joint Effort for Data assimilation Integration (JEDI) framework and demonstrate the relevance of the technique with the use of the Quasi-Geostrophic model (QG). Results show that when comparing a Lanczos and a block Lanczos, two effects compete against each other: the block requires less iterations to converge but each iteration takes more time. The fastest time to converge is reached when using around 16 members. Though, some issues are still encountered and requires to look more into the kind of operators we use in the block algorithm or it is subject to divergence.

  • Lehtinen, Silja
    KTH, School of Industrial Engineering and Management (ITM).
    Thermodynamic and Economic Evaluation of Hybridization Biomass-solar for a Cogeneration Power Plant in a Cuban Sugar Mill, George Washington2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study evaluates the thermodynamic and economic performance of hybridization of biomass-solar for a cogeneration power plant in a Cuban sugar mill, George Washington. The evaluation is performed by varying the parameters of the thermal power block and considering scenarios with 1) bagasse and marab√ļ, 2) bagasse and solar field, and 3) bagasse, marab√ļ and solar field as heat sources for the cogeneration cycle. The most feasible configuration combines all the three heat sources having the superheated steam parameters of 100 bar and 540 ‚ĀįC and the solar field aperture area of 88,560 m2 using SkyTrough collectors. The NPV for the proposed system is 30.97 million USD which indicates that it is economically feasible and the LCOE of 0.091 USD/kWh is in the range of a typical LCOE for biomass electricity generation with a stoker boiler (0.06 ‚Äď 0.21 USD/kWh).

  • Kubulenso, Saga
    KTH, School of Industrial Engineering and Management (ITM).
    The OSeMOSYS teaching kit ‚Äď an example of open educational resources to support sustainable development2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis explores the role of open online educational resources as a tool for building longterm capacity for Sustainable Development planning. The focus is on energy and climate mitigation related to SDG 7 and 13. In particular the thesis explores medium to long term energy systems analysis and modelling - a critical activity for energy infrastructure development. An open teaching kit and online course for the Open Source energy Modelling System (OSeMOSYS) is presented. The OSeMOSYS teaching kit is derived from training and teaching experience on the use of the tool by the OpTIMUS community of practice and its partners.

    Several international organisations and consortium have long experience in carrying out capacity building initiatives and programmes in energy systems analysis and modelling across the globe. Yet, knowledge transfer, dissemination and application of newly learned tools are not as effective as they might be. Enabling conditions for sustained, effective and contentflexible long-term capacity building and teaching in energy systems analysis is necessary. Yet few accessible resources exist. Availability and access to open educational materials can contribute to the development of solid and long-term capacity, particularly in developing country contexts, which often rely on international support for such activities.

    The OSeMOSYS open educational resources, including the online course presented in this thesis, provide a ready-made example of an energy systems analysis course that can be directly deployed at higher education levels and in-house capacity building initiatives. Its open nature promotes and facilitates the development of a network of practitioners who can contribute back to the community. Users have the option of contributing to, using and reconfiguring materials and course examples of varying levels and specifics. These can then be shared and taken up by the community of practice.

  • Kiljanov, Grigory
    KTH, School of Industrial Engineering and Management (ITM).
    Accumulation of energy in autonomous power plants using renewable energy sources2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Kiljanov G.M. Energy storage in autonomous power plants using renewable energy sources, 2017 - p.104, 11 tables, 40 pic. Head Bessel V.V., Professor, Ph.D. Department of Thermodynamics and Thermal Engines.

    An analysis of existing energy storage devices in the world is carried out. The scientific and technical basis of energy storage. The device and the operating principle of an autonomous combined power plant with an energy storage device are considered. On the basis of the technological calculation, an optimal combination of a wind generator, a system of solar panels and a reservoir, which can provide reliable and uninterrupted power generation, was chosen. The economic efficiency of the project on the use of combined medium power plants at gas production facilities in remote areas was estimated. Conclusions are drawn about the advisability of introducing energy systems based on renewable sources with energy storage devices at the country's enterprises.

  • Lin, Jiacheng
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Teng, Haoran
    KTH, School of Industrial Engineering and Management (ITM).
    Influence of Nucleation Techniques on the Degree of Supercooling and Duration of Crystallization for Sugar Alcohol as Phase Change Material: Investigation on erythritol-based additiveenhanced composites2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Utilizing Phase Change Materials (PCM) for Latent Thermal Energy Storage (LTES) applications have previously been extensively researched as a measure to reduce greenhouse gas emissions from energy consumption. In order to make use of the waste heat from industrial processes for LTES purposes, a new demand emerged for PCMs capable of phase change in mid-temperature ranges of 100 ¬įC - 200 ¬įC. This higher temperature requirement made most of the previously studied material inapplicable as they had much lower melting and solidification temperatures. With this in mind, a new generation of PCMs consisting of Sugar Alcohols (SA) has been proposed.

    Erythritol is seen as an especially promising SA with good thermophysical properties for LTES purposes. However, it has been shown to suffer from severe supercooling, which makes it unreliable in real applications. To eradicate this issue, two additives, Graphene Oxide (GO) and Polyvinylpyrrolidone (PVP) at varying mass fractions were mixed with pure erythritol to form a composite which was studied using the Temperature-history (T-history) method to determine its effectiveness in reducing supercooling. Results show that at its most effective mass fraction, GO reduces supercooling by 28 oC and a 31 oC reduction is seen by the addition of PVP. The impacts on the duration of crystallization was also documented and analyzed using the same method. It was observed that the duration of crystallization was increased with increasing mass fractions of the additives.

    Other important properties of the composites were also studied in order to determine the overall feasibility for industrial applications. It includes analysis of the storage capacity through latent heat, changes in viscosity along with impacts on thermal diffusivity of the composites.

  • Isaksson, Maja
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Stjerngren, Ellen
    KTH, School of Industrial Engineering and Management (ITM).
    Opportunities, Barriers and Preconditions for Battery Energy Storage in Sweden: A Study Investigating the Possibilities of Grid Connected Lithium-Ion Battery Energy Storage Systems in the Swedish Electricity Market2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The global energy system is under transformation. The energy transition from a centralized, fossil fuel based energy system to a more decentralized, renewable energy based system will challenge the balancing of electricity supply and demand. This stresses the importance of grid flexibility. In this challenge, energy storage will play a valuable role as it can provide flexibility and support the renewable energy integration. More specifically, lithium-ion battery energy storage systems (Li-ion BESS) demonstrate technological advantages and valuable application possibilities in the electricity grid. This thesis examines opportunities and barriers for deployment of grid-scale Li-ion BESS in the Swedish electricity market, and provides an overview of different perspectives of possibilities with BESS from several market actors. The purpose of the exploratory study is to gain an understanding of prospects for grid-scale BESS in Sweden.

    Through a comprehensive literature study and an empirical study, based on fourteen interviews with various actors in the electricity market, data was collected and analyzed. The analysis of the empirical findings resulted in two tables summarizing opportunities and barriers for implementation of BESS in Sweden. The opportunities and barriers are categorized into three hierarchical levels; contextual level, power system level and BESS level, referring to where in the system the benefits or hinders are localized. Also, key discussion points related to BESS (such as storage time perspective, ownership, grid services, cost, price signals and knowledge gap) are explored and evaluated. Furthermore, to understand the possibilities for grid-scale BESS in Sweden, a potential business setup for BESS is assessed and analyzed to identify preconditions for BESS to be attractive on the Swedish electricity market.

    The findings of the thesis indicate that grid flexibility is most likely going to be a considerable issue within 10-20 years. By the time of the potential nuclear phase out in Sweden, there will be major instabilities in the electricity grid if solutions are not in place. Therefore, keys to grid flexibility need to be evaluated and planned for well in advance, and the findings indicate that BESS could be a possible part of the solution. Until now, the regulatory framework has been perceived as rather unclear when it comes to energy storage, which has led to uncertainties among the market actors. These unclarities are about to be clarified with new laws and regulations, which will enable potential businesses for BESS. With the changes in the regulatory framework in place, we see an opportunity with new actors on the market. Our analysis shows that the BESS owner will most likely be a commercial actor, to enable utilization of a BESS for combined applications. An important factor, affecting the possibilities of implementing BESS on the Swedish electricity market, is the cost of BESS. We consider the cost aspect as vital for the likelihood of deploying BESS in Sweden. Based on our main findings, we conclude several preconditions for the deployment of BESS in Sweden. These are; decreased costs of BESS, acceptance from market actors, increased knowledge, a trading platform for grid services provided by a BESS, coordination between markets and electricity load forecasts. We believe that if these preconditions are fulfilled, Li-ion BESS has a chance to affect and have an impact on the Swedish electricity market.

  • Wang, Haotian
    KTH, School of Industrial Engineering and Management (ITM).
    Influence on tip leakage flow in a compressor cascade with plasma actuation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As one of the key components of aero engines, compressor is required to endure higher pressure,  possess  higher  efficiency  and  wider  operating  range. Intensive studies have been made on tip leakage flow and researchers find that by reasonably organizing tip leakage flow, aero engines are  more likely to achieve better performance and reliability. Conventional flow controlling methods  like casing treatment and micro jet could substantially modify tip leakage flow, unfortunately with  a price of additional loss, not to mention the difficulty in manufacturing such structure. Whereas  plasma actuation  flow control method  uses  plasma actuators,  such equipment is easy  to  build,  responses  fast  and  has  a  wide  excitation  bandwidth.  This  method  has  become  a  new  trend  in  internal flow active control field. 

    In this research, a phenomenological model is adopted to simulate DBD plasma actuation in the  flow field inside a compressor cascade. The aim is to find out how plasma actuation will influence  tip  leakage  flow.  Meanwhile  possible  means  to  improve  plasma  actuation  performance  are  discussed. 

    First of all, numerical simulation of flow inside a compressor cascade without plasma actuation is  conducted to validate accuracy of the numerical methodology adopted and then determine one  numerical  approach  that  satisfies  specific  needs  sufficiently.  Meanwhile,  influence  of  casing  movement on tip leakage flow as well as possible mechanism of tip leakage vortex core generation  is investigated in detail. The results indicate:   

    1. Generating position of tip leakage vortex moves towards leading edge with increasing moving  speed of shroud. 

    2. As shroud moving speed increases, trajectory of tip leakage vortex moves away from suction  side of blade and closely towards shroud. 

    3. Casing movement  tends  to  transform  tip leakage vortex  from  circular  to  oval  shape  due  to  circumferential shearing. 

    4. Casing  movement  has  little  influence  on  total  pressure  field  concerning  absolute  pressure  value. While total pressure loss does reduce slightly with increasing moving speed of shroud. 

    5.Vorticity  transport  from  tip  clearance  into  passage  may  be  contributing  significantly  to  generation of tip leakage vortex inner core. 

    Secondly, a simplified model of DBD plasma actuation based on literature [1] is derived and applied  through  UDF  function  of  commercial  software  Fluent  into  the  flow  field.  Different  actuation  positions,  voltages  and  frequencies  are  applied  in  simulation  and  compared.  After  that  casing  movement is included. Main conclusions are as follow:   

    6. Plasma  actuation  shows  significant  suppressing  effect  on  tip  leakage  vortex  on  both  size,  trajectory and strength. 

    7. The suppressing effect on tip leakage vortex grows stronger as actuator moves towards leading  edge. 

    8. Increasing actuation voltage results in stronger suppressing effect on tip leakage vortex. 

    9. Plasma actuation can effectively improve total pressure loss situation near shroud region with  increasing actuation power. 

    10. Increasing actuation frequency results in stronger suppressing effect on tip leakage vortex as  well. Additionally, frequency performs slightly better than voltage.

    11. Casing  movement  tends  to  weaken  suppressing  effect  of  tip  leakage  vortex  by  plasma  actuation. More  actuation  power  is  needed  to  achieve  sufficient  suppressing  effect  in  real  compressors. 

  • Hadziomerovic, Dado
    KTH, School of Industrial Engineering and Management (ITM).
    Energy Systems Simulation on an Urban District-Level2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The development of urban-scale energy systems modelling on a district-level is presently the target of many research organisations because of the growing interest in assessing the effect of energy efficiency throughout the full energy chain in urban district environments. This Master thesis includes an overview on energy use with aggregation at building- and a geographically restricted residential area level. The research was focused on three aspects to achieve sustainable development: selection of a modelling tool within energy engineering, energy systems modelling on a building-level and on an urban district-level, and an analysis of the magnitude of energy flows (heat and electricity) between different system components and also on an aggregated level on an hourly basis at predefined climate conditions.

    To reach the objectives, an extensive screening of 129 modelling tools was conducted based on nine different parameters provided in table form. Moreover, a more in-depth literature study was conducted in text form where a total of 21 modelling tools were reviewed addressing a wide range of characteristic features within each tool. The chosen modelling tool was ‚ÄúSimulationX‚ÄĚ for this work. Other tools considered were e.g. EnergyPlan, TRNSYS, and Homer. SimulationX was mainly chosen because of the expected high level of detail that could be achieved in the modelling process and the wide range of components available to design an energy system, both on a building-level and on an urban district-level. Furthermore, a design of the requested architecture of the energy system on an urban district-level has been established representing the full energy chain from natural resources to energy end-use services. By the use of the SimulationX software and the Green City library specifically used in this project, a total number of three concepts were created with the general idea to present the difference between individual energy solutions of households compared to integrated solutions of multiple households for a part of a district in the area of Uppsala to emphasise the possible synergistic effects. The first and second concept describe the integrated energy system within a building while the third concept simulated a restricted residential area consisting of 67 single-family houses, 197 terraced houses and 120 dwelling apartments.

    Based on the results from the simulations the total annual energy demand for electricity and heat was estimated to be 4653 and 11 153 kWh, respectively for a single-family house. For a terraced house, the electricity and heat demand amount to 4000 and 7122 kWh, respectively. On an urban district-level, the model design indicates that the heat demand of 2604 MWh can be sufficiently met throughout the year with a TES integrated in the system, but the total annual electricity supply is 436 MWh lower than the demand. The main advantages with the chosen modelling tool are the predefined parameters and user profiles available as well as the high level of detail that can be achieved on a building-level. However, the tool currently lacks the ability to estimate CO2 emissions and calculate the investment costs required for the different energy system models. For future recommendations, an economic analysis can be conducted to calculate the investment costs required for different energy system designs. This will help future decision-making processes in evaluating the feasibility of an energy system and possibly what components that significantly might affect the total investment costs.

  • Gustafsson, Katarina
    KTH, School of Industrial Engineering and Management (ITM).
    Techno-economic analysis for the conversion of utility-scale heat pump to a refrigerating machine for district cooling application: a case study at Norrenergi2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heat pumps with wastewater as a heat source are used at Solnaverket, Norrenergi to provide a base load district heating and some cooling services. Currently, the waste cooling produced from the heat pumps is needed to supply a growing demand for district cooling during hot summer days. At the same time, the heating demand is very low in summer. Part of the heating base load could instead be imported from Stockholm Exergi with very low production costs for district heating in the summer. While the heating cost decreases as a result, the supply of district cooling becomes a more expensive product for Norrenergi.

    Bromma sewage treatment plant will presumably shut down in 2027, which means that Norrenergi needs to replace the wastewater with for example lake water as heat source. This study investigates how the district cooling production could become more economical and resource efficient by converting a heat pump to a chilling machine for summer operation.

    The technical possibilities of a redesign have been investigated. This resulted in three alternatives; two of those focused on converting a heat pump to a refrigerating machine in the summer with the possibility to use lake water as a cooling source. The third alternative connected the evaporator directly to the district cooling network, but still required a heating load in order to operate. An operational model of how the district cooling network prioritizes which cooling equipment starts first was built to simulate the converted heat pump behavior for three representative historical cooling demands.

    The option of converting a heat pump to a refrigerating machine with an intermediate cycle connected to the condenser was considered as the best investment. The sensitivity analysis showed that the climate data is the factor that affects the results the most, followed by the electricity price. Before Bromma sewage plant shuts down, the annual savings are too low to recommend an investment. However, this alternative was profitable considering an increased cooling demand and the inclusion of a cooling buffer energy storage in the future. A scenario considering the whole system profit also showed to be profitable. After Bromma sewage plant shuts down, the alternatives must be compared with the investment in new chilling machines, which are expensive, and potentially replacing heating capacity. Therefore, an investment could be recommended for this case, but needs further investigation.

  • Garcia Redondo, David
    KTH, School of Industrial Engineering and Management (ITM).
    Parallel CO2 refrigeration system compared to state-ofthe-art solution in supermarket application2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis compares the performance of two trans-critical CO2 refrigeration systems, the state-of-the-art booster system and the standard parallel system. The main goal is to quantify the efficiency difference between these two systems.

    By using computer assisted calculations both systems are modelled, then energy results are obtained. Different configurations for the parallel solution are considered. Adding direct expansion sub-cooling or using indirect sub-cooling, gives a significant improvement in the performance of the system. Also, a heat recovery control system is considered to operate when a heat load is demanded.

    The calculations indicate that standard parallel system with the assumptions given, become a more efficient solution with a COP of 6,8 and 3 for the MT level and LT level respectively. This translate in energy saving of 9% and 7,6% when the heat recovery control system is used in comparison with the state-of-the-art booster system.

  • Garc√≠a, Jos√© Angel
    KTH, School of Industrial Engineering and Management (ITM).
    Development and validation of a combined heat and power plant model for integration in DYESOPT2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The liberalization of electricity markets and a growing penetration of renewables has led many countries to feel changes in the operation of their grids. The boundary conditions for the operation of conventional power plants are changing and, as such, an improved understanding of the varying loads and prices on the electricity grid is required to assess the performance of emerging combined cycle gas turbine (CCGT) concepts and to further optimize their design for these new markets in the pursuit of increasing their profitability, especially when considering co-generation of heat and power. A clear consequence of such renewable integration is the need for these plants to be more flexible in terms of tamping-up periods and higher part-load efficiencies. In the pursue of greater power plant dispatch flexibility, new ideas and technologies are being analyzed and tested in new and in already existing installations. Power plant simulations in modeling tools offer the possibility to have first estimates of how profitable it is to implement a new technology, operation scheme or dispatch strategy without having to invest in building the systems or applying any change to the operation of a real power plant. DYESOPT is one of the modeling tools used by researchers and consultants at KTH for simulating and doing techno-economic analyses of thermal energy systems. It has proven to be an accurate and customizable tool for the task. In that sense, the work in this thesis project is to enhance this modeling tool by incorporating a new power plant layout, which will be used in future works for increasing dispatch flexibility of a pilot combined heat and power plant. The power plant modeled consists on a topping Brayton cycle coupled to a bottoming Rankine cycle with three pressure levels, reheat features, and two extractions to feed a district heating system (one extraction from the low-pressure section of the steam turbine, and other from the economizer section of the heat recovery steam generator). The model was built considering the novel ideas to be tested on it and was then validated by comparing its performance against operational data provided by a real power plant during steady state conditions and part load transients. The results show that the validated model is of high relevance for further investigations regarding flexibility increase of CCGT-CHP power plants.

  • Yuning, Jiang
    KTH, School of Industrial Engineering and Management (ITM).
    LCA of Microgrid System: a Case Study at ‚ÄėNorth-five Islands‚Äô of Changshan Archipelago, China2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Microgrid can provide stable, clean, and sustainable electricity supply for remote places since it can operate on renewable energy sources and work isolated from the utility grid. This thesis evaluates the life cycle greenhouse gas (GHG) emissions of the microgrid system which is located at the ‚ÄėNorth-five Islands‚Äô of Changshan archipelago in China. The existing electricity generation technologies of the microgrid system are wind turbine, PV system and diesel generators with the capacity of 2 MW, 300 kW and 2046 kW, respectively. The total demand of electricity (362.2 GWh) will be supplied by the wind turbine, PV system and diesel generators with 32.03%, 2.36% and 65.62%, respectively, if the microgrid system is required to supply the electricity demand for the ‚ÄėNorth-five Islands‚Äô area alone under the islanded mode during 20 years lifespan. The thesis uses the Life Cycle Assessment (LCA) to evaluate the life cycle GHG emissions of the microgrid system. The life cycle stages of this study include: raw material extraction, manufacturing, transportation and operation. In order to assess the environmental benefits of the microgrid system, three electricity supply options ‚Äď ‚Äėmicrogrid electricity supply option‚Äô, ‚Äėgrid extension electricity supply option‚Äô, and ‚Äėconventional fossil diesel generators electricity supply option‚Äô are designed to evaluate the life cycle GHG emissions for supplying 20 years electricity demand (362.2 GWh) of the ‚ÄėNorthfive Islands‚Äô.

    The results show that the life cycle GHG emissions of the ‚Äėmicrogrid electricity supply option‚Äô are 223.19 million kgCO2eq. Compared to the ‚Äėgrid extension electricity supply option‚Äô and ‚Äėconventional fossil diesel generators electricity supply option‚Äô, the net savings of the GHG emissions are 70.56 and 112.18 million kgCO2eq, respectively. It mainly results from the differences of the electricity supply methods of the three electricity supply options. For the ‚Äėmicrogrid electricity supply option‚Äô itself, the operation stage takes the most responsibility of the life cycle GHG emissions with 97.6%. The raw material extraction, manufacturing and transportation stages account for 1.93%, 0.44% and 0.026%, respectively. For the system components of the microgrid system, the wind turbine, PV system, diesel generators, energy storage system, and cables account for 0.34%, 0.18%, 97.75%, 0.60%, and 1.12%, respectively, of the microgrid system‚Äôs life cycle GHG emissions.

    The thesis conducts the sensitivity analysis of diesel burn rate efficiency (L/kWh) of the microgrid system‚Äôs diesel generators due to a large quantity (60.84 million L) of diesel consumption by the diesel generators during 20 years operation time. According to the results of the sensitivity analysis, the diesel burn rate efficiency can directly impact the diesel consumption of the diesel generators, and consequently has a significant impact on the life cycle GHG emissions of the ‚ÄėNorth-five Islands‚Äô microgrid system. Since the diesel burn rate efficiency represents the amount of diesel consumption, this results highlight the significance of any factors that affect the diesel consumption (e.g. quantity of diesel, temperature, altitude, etc.), in affecting the life cycle GHG emissions of the ‚ÄėNorth-five Islands‚Äô microgrid system. In addition, the thesis performers the sensitivity analysis of renewable energy (wind and solar energy in specific) fraction of the studied microgrid system because of the huge potential of available renewable energy (63.65 MW of wind turbines) nearby the microgrid system. The results of the sensitivity analysis show that the life cycle GHG emissions of the microgrid system decrease linearly with the increase of wind and solar energy fraction. Particularly, the life cycle GHG emissions of the microgrid system decrease 1.46% (3.26 million kgCO2eq) and 1.37% (3.05 million kgCO2eq) with an increase of 1% in wind and solar energy, respectively.

  • Public defence: 2019-12-17 10:00 Sal C, Electrum, Kista
    Ghoorchian, Kambiz
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Graph Algorithms for Large-Scale and Dynamic Natural Language Processing2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Natural Language Processing, researchers design and develop algorithms to enable machines to understand and analyze human language. These algorithms benefit multiple downstream applications including sentiment analysis, automatic translation, automatic question answering, and text summarization. Topic modeling is one such algorithm that solves the problem of categorizing documents into multiple groups with the goal of maximizing the intra-group document similarity. However, the manifestation of short texts like tweets, snippets, comments, and forum posts as the dominant source of text in our daily interactions and communications, as well as being the main medium for news reporting and dissemination, increases the complexity of the problem due to scalability, sparsity, and dynamicity. Scalability refers to the volume of the messages being generated, sparsity is related to the length of the messages, and dynamicity is associated with the ratio of changes in the content and topical structure of the messages (e.g., the emergence of new phrases). We improve the scalability and accuracy of Natural Language Processing algorithms from three perspectives, by leveraging on innovative graph modeling and graph partitioning algorithms, incremental dimensionality reduction techniques, and rich language modeling methods. We begin by presenting a solution for multiple disambiguation on short messages, as opposed to traditional single disambiguation. The solution proposes a simple graph representation model to present topical structures in the form of dense partitions in that graph and applies disambiguation by extracting those topical structures using an innovative distributed graph partitioning algorithm. Next, we develop a scalable topic modeling algorithm using a novel dense graph representation and an efficient graph partitioning algorithm. Then, we analyze the effect of temporal dimension to understand the dynamicity in online social networks and present a solution for geo-localization of users in Twitter using a hierarchical model that combines partitioning of the underlying social network graph with temporal categorization of the tweets. The results show the effect of temporal dynamicity on users’ spatial behavior. This result leads to design and development of a dynamic topic modeling solution, involving an online graph partitioning algorithm and a significantly stronger language modeling approach based on the skip-gram technique. The algorithm shows strong improvement on scalability and accuracy compared to the state-of-the-art models. Finally, we describe a dynamic graph-based representation learning algorithm that modifies the partitioning algorithm to develop a generalization of our previous work. A strong representation learning algorithm is proposed that can be used for extracting high quality distributed and continuous representations out of any sequential data with local and hierarchical structural properties similar to natural language text.

  • Tyagi, Abhimanyu
    KTH, School of Industrial Engineering and Management (ITM).
    Simulation of a scaled down version of a run-around coil heat recovery system on COMSOL¬ģ Multiphysics.2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Due to changing anthropological activities, the consumption of resources is continuously increasing. As humans are spending more time indoors, the energy demand is also increasing. The building sector is a major consumer of energy. In buildings, space heating is important to maintain a comfortable space. For this, apart from increasing the thermal insulation and wellconstructed buildings, air-air heat recovery systems(among others) are being used to precondition the ambient air, so that the exhaust air from the conditioned space can pre-heat/ pre-cool the ambient air, depending on the season.

    In this thesis report, the run around coil heat recovery systems are discussed. A Multiphysics model on COMSOL¬ģ Multiphysics was created which was a scaled down version of an actual system. Real-life boundary conditions were provided as inputs to the model and its results were subsequently discussed. First, a literature review of the different air-air heat recovery systems was done, followed by discussing their various advantages and disadvantages. Next, an introduction to COMSOL¬ģ was made, followed by the construction of the model and the materials, mesh and physics conditions which were used along with the solver configuration. In the end the model showed success in pre-heating the ambient air in winter and pre-cooling it in summer seasons. Along with that other results were also discussed. In the end some options for future work on the project were also discussed.

  • Thermos, Ioannis
    KTH, School of Industrial Engineering and Management (ITM).
    Albania and North Macedonia: The evolution of the electricity system under the scope of climate change2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Albania and North Macedonia, along with the rest of the Balkan region, have been developing since the early nineties and have achieved an upper-middle income status. Along with this development, the energy demand grew as well. However, the current electricity system in these two countries has not significantly evolved during the past 35 years since the majority of the infrastructure was built during the Soviet era. It is therefore crucial to upgrade the existing system to avoid power shortages and to reduce electricity losses. At the same time, the effects of climate change are becoming more and more obvious and pose a direct threat to the affordability of electricity generated by large hydropower plants during the last decades.

    This study examines the evolution of the electricity sector of Albania and North Macedonia for the next 20 years. It will put to the test the current electricity system extrapolated into the future, the changes that might be necessary to be made to tackle the effects of climate change and the nations’ commitments to reduce the impacts of a changing climate. The first step is to understand the energy system in each country, starting with their available resources, historical capacities, electricity demand etc. Both countries are almost identical in terms of sizes with each one having an electricity supply system of around 2 GW in capacity and a final electricity consumption of 5,563 GWh and 6,104 GWh in 2017 for Albania and North Macedonia respectively. On the other hand, the systems differ qualitative. To be more specific, almost 100% of Albania’s generation capacity is hydropower, while the North Macedonian system is based mainly on lignite (coal power) and to a smaller extend on hydropower. Since this study focuses on the effects of climate change on electricity produced from hydropower, a correlation was made to link the reduced precipitation with river flow and in the end hydropower generation. The correlation results show that an average decrease in precipitation of 1.6% and 1.9% can be expected in 2037 compared to current levels, that will lead to a decrease in hydropower generation of 3.3% and 4% for Albania and North Macedonia respectively.

    Then the cost-optimization model, using OSeMOSYS, was created to depict those changes. First, the business-as-usual scenario, used as a reference scenario, extends the current situation into the future. In a few words, Albania and North Macedonia will invest in hydropower and wind capacity respectively to cover the increasing electricity demand. Secondly the Climate Change scenario was investigated, where the decrease in precipitation was considered, but according to the model, electricity imports will increase instead of investing in additional capacity. The third scenario was the Increased Renewables scenario, where the countries fulfil their obligations to install more renewable capacity and diversify their electricity mix. This approach will reduce their vulnerability to climate change and electricity imports but will come at a great investment cost for the countries’ economy. Overall, results show that the regional power sector will be affected by climate change. However, the biggest challenge will be to tackle the annual and seasonal variation in hydropower generation rather than the general decreasing trend in precipitation over the years. To be more specific, annual hydropower generation can even double between a dry and a wet year in some cases. However, under the climate change scenario annual hydropower generation will only decrease by 5.7% and 2.7% during a wet and a dry year compared to the business-as-usual scenario respectively.

  • Jalken√§s, Frida
    KTH, School of Industrial Engineering and Management (ITM).
    Evaluation tool for large scale onshore wind power projects2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sweden has a goal of having 100% renewable electricity production by 2040. To reach this goal, wind power is one of the most important energy sources that needs to be heavily expanded. However, finding a good project site and realizing a project is a process that takes several years and can be difficult to achieve. Between 2015 and 2018, no less than 76% of Swedish wind power projects applying for permits were rejected.

    As an industry player with the aim of becoming fossil free, Pöyry has the interest to pursue Sweden reaching its goal. Pöyry has long experience of wind energy development and has now requested a method that can evaluate and compare Swedish wind power projects in all stages with the aim of identifying the best available project to proceed with. The objective of this thesis is thus to investigate factors that are critical for developing profitable projects, identify the largest expenses and create a tool that evaluates projects based on several parameters.

    A literature review is performed to obtain knowledge about wind power project development and data is collected from various projects in Sweden from 2016 and onwards to get an updated view with information and valuable numbers from realized projects. An analysis is then carried out with the aim of finding the most important factors that can affect the development of wind power projects, positively or negatively. This is followed by an identification of the most significant expenses in a project, whereupon a simplified but realistic way of calculating these are created. Lastly an evaluation tool is developed using Excel, with the purpose of evaluating projects, finding risks and estimating costs as well as electric energy production. Finally, candidate projects can be compared, helping developers finding the most beneficial and environmentally friendly projects.

  • Elf, Julia
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Svensson, Ludvig
    KTH, School of Industrial Engineering and Management (ITM).
    Standardization in Sustainability Transitions: A Study on Stakeholder Attitudes and Power Relations During the Standardization Process in the Vehicle-to-Grid Ecosystem2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The electrification of the transportation sector plays an important role in the sustainability transition as successful electric vehicle (EV) integration allows for the reduction of CO2 emissions. Moreover, bidirectional capabilities of the EVs (vehicle-to-grid) further facilitate this transition by supporting the electricity grid while lowering the cost of ownership of EVs when revenues from grid-supporting services are split between stakeholders. Due to sustainability challenges facing several domains, fundamental transformation processes are needed to transition away from our current global energy system. However, with the strong inertia of the current system together with the sheer complexity and vexed interests during transitions, neither private markets nor government agencies seem likely to spur this transition on their own. Transitions are thus political processes, in which standards can play an important role since they point to the direction of the transition.

    This thesis investigates the role of standardization in sustainability transitions. The aim was to improve the understanding of the diverse stakeholder attitudes towards the standardization process of the communication protocol between the vehicle and its charging equipment. While exploring this topic, the thesis further aimed to investigate the power relations that govern the interactions and coordination efforts between the diverse stakeholders involved in the vehicle-to-grid (V2G) standardization processes. To achieve this, a qualitative study was conducted where two transcripts from the California Energy Commission, adding up to a total of 667 pages, were coded in a mixed inductive-deductive manner. In addition, as a complement, 13 expert interviews were conducted.

    The results showed that power was expressed by actors on (and between) all levels in the system. Mutual dependency was the most frequently expressed power relation among the actors. The mutual dependency was assumed to be widely present due to the interdependent nature between the components in the V2G system. The automotive manufacturers were observed to have a strong position in the vehicle-to-grid ecosystem and it was noted that other actors conformed with their political and/or economic goals. Another finding related to power was the sense of powerlessness and frustration expressed by actors on all levels, likely enabling the status quo to prevail. There was also clear frustration towards policymakers concerning the lack of policy direction and actors expressed the need for market signaling. The policymakers seemed to adhere to both disruptive innovations and the existing regime, causing uncertainty in policy decisions. The empirics also showed that the standardization discussions have little focus on competition between standards at this point of the transition. The debate seemed to rather be shaped by the conflict between advocates and opponents of standardization, where the opponents argued against standardization due to fear of prematurely mandating a single standard. Advocates dominated over opponents at this point of the transition and the communication standard, ISO 15118 seemed to have significant industry support. Automotive manufacturers were found to be the most vocal stakeholder group against standardization. Furthermore, the results highlighted the functions and features of standards commonly mentioned in the V2G standardization discussions, where compatibility, market signaling, and future proof features belonged to the most frequently mentioned.

  • Quesada Zeljkovic, Joaquin
    KTH, School of Industrial Engineering and Management (ITM).
    Construction of a Heat Transfer Rig based on Energy Balance for Rapid Production of Correlations for Additively Manufactured Geometries2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis has set the first milestones towards building a Nusselt number correlation that adapts to the current state of art designing and manufacturing processes at Siemens Industrial Turbomachinery AB, focusing on cooling mini-channels produced with Additive Manufacturing. 

    Additive manufacturing (AM), also known as 3D printing, is a gamechanger technology that has revolutionised manufacture and design know-how, bringing down production cost, time and waste. There are techniques within AM that can be applied in the gas turbine industry. Particularly, Selective Laser Melting (SLM) can be utilised to build high-temperature-alloy components without the design constraints imposed by conventional manufacturing. However, when assessing the performance of these AM components, challenges arise due to surface roughness inherent to the SLM process.

    The goal is to assess SLM parts for a specific application: thermal performance of AM cooling minichannels. This thesis presents the design, construction and validation of a heat transfer experimental rig, capable of assessing the Nusselt number in SLM single mini-channel samples. The SLM samples vary in the material alloy used for its fabrication, the shape of the mini-channel, and hydraulic diameter. The results show that SLM channels have a higher Nusselt number than smooth, conventionally manufactured channels. This heat transfer enhancement comes at a cost: an increased friction factor coefficient, which was the subject of study in a parallel thesis conducted in the same facilities. The relative friction growth of an SLM sample is significantly higher than the increase in relative Nusselt number for the same SLM when compared to the smooth channel performance.

    These results are aligned with the expectations, matching the general trends observed in the literature. However, some contradictions with other studies were obtained: surface roughness, the key factor affecting flow performance, yielded inconclusive effects for the results obtained in the present thesis. Further assessment and validation of the heat transfer rig built is to be pursued.

  • Martin, Guillaume
    KTH, School of Industrial Engineering and Management (ITM).
    District Heating Networks Design2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    District heating networks are a solution to decrease the amount of CO2 emission in the atmosphere and a mean to increase the share of renewable energy in the energy mix. This degree project, conducted at Engie Réseaux, investigates the best options to design them. The challenges and the constraints of their design will be developed and the tools created to achieve it will be presented. This thesis exposes the major climatologic, economic, and energetic parameters to take into account when designing a network and shows the methodology used in these three fields.

  • Nikzad, Dario
    KTH, School of Industrial Engineering and Management (ITM).
    Techno-economic analysis of integrating renewable electricity and electricity storage in √Öland by 2030: Overview of the current energy situation and definition of four possible environmentally friendly pathways2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study focuses on the possible positive impacts derived from implementing innovative energy solutions to the Åland energy system by 2030. Four scenarios are formulated in order to determine feasible solutions in economic and technological terms. At the present most of the energy supply relies on the power exchange with mainland by subsea interconnections. The archipelago’s main challenge is to reduce the high dependence from the main importer (Sweden) by increasing the use of local renewable energy sources.

    Wind power results to be the most favorable form of variable renewable energy (VRE) available. ‚ÄúBehind the meter‚ÄĚ photovoltaic (PV) rooftop solar panels, biomass combined heat and power (CHP) generation and a Li-ion battery system are considered as supportive solutions to wind power. The simulations made with RetScreen and EnergyPLAN confirm that solar power and a battery system can only have a modest role compared to wind power. A final economic analysis assesses the revenue projections for the new technologies implemented. The results indicate a very positive investment potential for the new wind farms, coupled with a proper Li-ion battery solution.

    Additionally, the thesis investigates the best options for solving frequency and voltage imbalances, appearing after the implementation of intermittent energy sources. A flywheel technology has been included in the scenarios in order to enhance the primary frequency control of the whole system.

  • Pastor Pascual, Daniel
    KTH, School of Industrial Engineering and Management (ITM).
    Development of a GIS model for water accounting in Jordan: focus on irrigation and energy usage in the water sector2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With a water availability of less than 100 m3 per capita and year, Jordan is suffering extreme water-scarcity. To its intrinsic limited water resources more pressure is being added every year as a result of socioeconomic factors, such as the accelerated population growth, and a reduction of rainfalls and increase of evaporation as consequence of climate change. What is more, the poor condition of the water system together with a considerably high water consumption for irrigation are not helping in such drastic situation. In a country with scarce surface water, groundwater is the main resource. As a result, Jordan’s aquifers are being over abstracted and, consequently, depleted every year. Wastewater treatment arise as a solution as wastewater can be reused for irrigation, reducing the consumption of natural resources that can be, then, employed for domestic consumption. However, only 64% of people in Jordan is connected to the sewerage system, narrowing the amount of wastewater.

    Water shortages are the direct consequence of all of this, limiting the agriculture development and reducing quality of life. Urgent action is required in the country to mitigate the effects of water scarcity and optimize the resources. What is more, the incredibly high energy consumption of the water system is adding more pressure to the energy system, which relies mostly on energy imports such as fossil fuels. Thus, the water scarcity problem should be assessed considering its synergies and trade-offs with the energy system.

    Thus, the aim of this thesis is to create a Geographic Information System (GIS) model in which the water consumption was obtained and divided by sector with a resolution of 1 km2 . To do so, the population and water consumption per capita was taken into account for the domestic water consumption, while the evapotranspiration of the irrigated cropland in Jordan was calculated to ultimately obtain the water consumption in the agriculture sector. Then, taking advantage of the potential of a GIS model, the water consumption obtained in every spot was divided by source. Afterwards, the energy consumption of the water system is obtained. Lastly, three scenarios were built and simulated in order to analyze the consequence of the Jordan’s Ministry of Water and Irrigation policies, set to fight against water scarcity. The results showed that, although a mitigation of water scarcity and reduction of natural resources depletion can be achieved, even more strict action is required in order to reach a sustainable water sector, eliminating water shortages and reducing the pressure on the natural resources.

  • Danebergs, Janis
    KTH, School of Industrial Engineering and Management (ITM).
    Techno-economic Study of Hydrogen as a Heavy-duty Truck Fuel: A Case Study on the Transport Corridor Oslo ‚Äď Trondheim2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Norway has already an almost emission-free power production and its sales of zero-emission light-duty vehicles surpassed 30% in 2018; a natural next challenge is to identify ways to reduce emissions of heavyduty vehicles. In this work the possibilities to deploy Fuel Cell Electric Trucks (FCET) on the route Oslo-Trondheim are analyzed by doing a techno-economic analysis. The literature study identified that in average 932 kton goods where transported between the cities. The preferred road choice goes through √ėsterdalen and that an average load for a long-distance truck is 16 tons.

    The methodology used in the study is based on cost curves for both truck and infrastructure, and a case study with various scenarios is evaluated to find a profitable business case for both an FCET fleet and its infrastructure. The cost curves for trucks are based on total cost of ownership (TCO) as a function of hydrogen price, while the levelized cost of hydrogen (LCOH) is used to present the cost of infrastructure.

    An analysis was made to identify the trucks component sizes and a FCET for this route would require an onboard hydrogen storage of 46 kg, a fuel cell stack with a nominal power of 200 kW, a battery of 100 kWh (min SOC 22%), and an electric motor with a rated power of 402 kW. TCO was calculated both for an FCET based on the dimensioned components and a biodiesel truck. The results show that an FCET purchased in 2020 can be competitive with biodiesel with a hydrogen price of 38.6 NOK/kgH2. While the hydrogen price can increase to 71.8 NOK/ kgH2 if the FCET is purchased in 2030.

    To identify the most suitable infrastructure, four different designs of hydrogen refueling stations (HRS) were compared. Furthermore, hydrogen production units (HPUs) with both alkaline or PEM type water electrolyzer were compared. The analysis in this study showed that the most cost competitive option was a 350-bar HRS without cooling, which only can serve type III onboard storage tanks. A HPU with alkaline electrolyzer was the most price competitive alternative. In case each HRS is refueling more than 7 FCETs per day, an HPU in direct connection to HRS is the preferred infrastructure setup. Three HRS are required along the route to ensure a minimum service level for the FCETs.

    When the TCO of the fuel cell truck and LCOH of the hydrogen infrastructure were compared for a 2020 scenario, no feasible solution was identified. The cost of installing three HRS in 2020, serving a fleet of 14-24 trucks, would cost 16.0 ‚Äď 17.6 million NOK/year more than a fleet based on biodiesel trucks. In a future scenario, where both the FCET and infrastructure costs decrease due to expected learning curves, a business case can be found if at least 5 FCETs were refueling at each HRS on daily basis, which corresponds to a total fleet of approx. 24 FCETs.

    Finally, a set of clear recommendations on how to improve the techno-economic analysis in future studies are provided. Both by identifying areas lacking sufficient documentation and by providing steps how the tecno-economic model could be enhanced.

  • Daglish, Jonathan
    KTH, School of Industrial Engineering and Management (ITM).
    A Prefeasibility Analysis of a PV Mini Grid with Ice Plant on Buvu Island in Lake Victoria2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Improving energy access through the provision of sustainable electrification is fundamental to reducing poverty and facilitating development in many areas of rural Sub Saharan Africa. The region currently suffers from severe energy inequality, with 81% of people relying on traditional forms of biomass for direct energy provision. A major reason for this is that centralised grid infrastructure in many countries remains under maintained and grid extension to remote rural areas poses as too much of a financial burden to governments. Solar PV mini grids are gaining increasing attention from policy makers, researchers, and developers in the region as they pose as a means of leapfrogging the necessity for centralised fossil-fuel based infrastructures. Despite this, a high number of mini grid projects in SSA remain in their pilot stage. A major reasoning for this is the difficulty associated with accurately predicting the future electricity demand of currently un-electrified communities, and following on from that, it is also difficult to incentivize local economies once electricity is made available. The aim of this work was to assess the feasibility of Buvu Island on Ugandan Lake Victoria housing a PV mini grid and ice plant so as to provide power to its three un-electrified communities, and flaked ice to the local fishing industry. Structured interviews were first held with developers in the region so as to assess current weaknesses in mini grid design methodologies and following from that the literature was used to develop a suitable methodology. Data gathered in the field was used to predict the electricity demand of the island, and the HOMER optimization tool was used to size an appropriate system. The modelled system includes an AC-coupled PV array, a lead acid battery bank, a back-up generator, and a converter. Within Uganda, it is the role of the grid operator to provide capital investment for the distribution network. Accordingly, within this study, such a system has been proposed and costed, however this does not impact upon mini grid feasibility. A full financial analysis was used to as to assess the feasibility of the mini grid and ice plant project over a twenty year lifetime. A reference scenario returned promising results, with an IRR of 23.5%, DSCR of 529%, and NPV of $114,651 assuming that daily electricity demand is 695 kWh / day, and 2.5 tonnes of flaked ice are sold per day. The business model is highly dependent on the sale of ice and if average sales drop below under 1.6 tonnes per day over the project lifetime the system becomes unviable. To overcome the problems associated with unpredictability of demand and encouraged new uses of electricity, the mini grid in this work is scaled to match current demand on the island ‚Äď thus mitigating such risks. Additionally, a sensitivity study is included so as to fully characterise the range of mini grid operative models that may need be considered, and indeed the likely financial outcomes.

  • Costa, Matteo
    KTH, School of Industrial Engineering and Management (ITM).
    Resource energy efficiency measures for retail sector in Azerbaijan2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis work is part of a larger project financed by the European Bank for Reconstruction and Development (EBRD) and awarded by RINA Consulting S.p.A.. Azeri Retail will receive the loan from EBRD in order to refurbish its six new acquisitions in Baku, Azerbaijan. Azeri Retail considers the current Fresco format store a good technological and structural level, therefore Azeri Retail would like to replicate this state also for the new acquisitions. The thesis objective is to understand and analyse the current energy efficiency state and consequently propose some resource efficiency measures in order to replicate this new format for the new acquisitions to have a lower carbon footprint compared to the existing supermarkets belonging to the same brand.

    The thesis project is an energy audit comprising analysis of historical data, site visit to current Azeri Retail’s stores and consequent proposal of energy saving measures to be applied to the new acquisitions. In order to do this, three case studies have been developed: ATL, Project and REM.

    The first step has been the literature review about the energy utilization and carbon footprint of the retails sector, past energy audits, current and future policy framework in Azerbaijan. During this phase, it turned out that Azerbaijan doesn’t have a dedicated law for energy efficiency and therefore the construction phase doesn’t consider energy efficiency a primary target. Furthermore, in average the refrigerators represent the 40% of the total energy consumption of the supermarket.

    The site visit in Baku highlighted huge differences between the two brands’ buildings owned by Azeri Retail: Fresco brand belongs to high structural and technological level supermarkets, while Sebet doesn’t have any insulation on the envelope and the technical equipment is rather old.

    Microsoft Excel have been used in order to create the tool to perform the calculations. The thermal losses considered are the transmission losses, due to the building envelope, and the ventilation losses, due to the temperature difference between the exhaust indoor air and outdoor air. The internal gains are included in the model, in particular occupancy and solar loads. Furthermore, every case study considers different technical equipment according to what it is representing.

    All three built case studies refer to the geometry of the Fresco 2 building, since the comparison is more valuable if the buildings considered have similar geometry and activity inside. The ultimate aim of the modelling phase is to achieve good savings through measures in the REM case, since it is supposed to represent a useful list of saving measures to carry out during the actual refurbishment of the new stores. The measures proposed are: refurbishment of the envelope, purchase of a heat recovery heat exchanger, the exploitation of daylight through solar tubes and installation of LED bulbs, the refurbishment of cold rooms and the installation of double air curtains in the open refrigerated display cabinets. Great and positive results have been achieved during the modelling phase:

    ‚ěĘ Fresco stores can show very good structural properties and technological equipment and for this reason, each saving measures is additional to the already existing Fresco‚Äôs buildings status.

    ‚ěĘ Although Fresco stores‚Äô buildings are better than Sebet stores‚Äô ones and better than average practice in Azerbaijan, huge savings have been identified and this means that the new acquisitions could perform even better than the existing ones, mostly considering medium-low cost measures.

    The report closes with the overall comparison between the three case studies’ energy consumption and international benchmarks about food driven retails.

  • Choli, Marcelina
    KTH, School of Industrial Engineering and Management (ITM).
    Carbon dioxide emissions modelling in a power system model:: A case study of Germany and Poland2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aims to build a method for validating a power system model in the PLEXOS software. Special emphasis is put on the carbon dioxide emissions modelling. A case study of Germany and Poland is formulated in order to apply the created procedure to a European power model. The verification of emissions being one of the outputs, is divided into two phases. The first one focuses on the historical results from 2016-2017, which are compared with the chosen reference statistics and the emissions results obtained in another optimization tool. The second phase looks into the trends of emissions in the near future, i.e. time period between 2019-2025. OSeMOSYS as the second piece of software is used for benchmarking the results obtained by the PLEXOS model.

  • Chamarande, Th√©o
    KTH, School of Industrial Engineering and Management (ITM).
    Increasing Photovoltaic penetration rate on isolated grid using storage, overbuilding and curtailment: Case study of the Reunion Island2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the global context of GHG emissions reduction, insular isolated grids which are the most vulnerable systems in terms of fossil fuel dependency have to conduct their energy transition. Conventional units using fossil fuels are well adapted to those systems because they are dispatchable, reliable and flexible, so they can easily respond to grid requirements. Despite that, their large negative environmental impact and their dependence on geopolitical and economical context encourage islands to develop renewables. The Reunion Island wants to achieve a 100% renewable electricity mix by 2030. This ambitious goal can be achieved using the high solar resource’s potential in the region. However, this renewable potential is limited in the electricity mix because of issues related to uncertainty and variability of grid-connected PV systems.

    To deal with these issues a solution is to combined PV systems with storage systems to guarantee a firm power production. Considering the high costs for storage and the decreasing costs for PV systems, using overbuilding and curtailment could reduce the needs for storage and thus the cost related to it. The goal of this study is to develop an algorithm that will test and size this solution for the entire power production of the Reunion Island.

    To do so, satellite based data for solar resource (GHI and DNI) with resolutions of 1km² and 15min over the year 2018 were available from the SUNY model. These data were evaluated by a comparison with 13 ground measurements stations for the GHI and two trackers for the DNI in terms of power and energy. It was shown that estimation errors were quite large (relative RMSE between 27.5% and 78.8%) and that stations with the higher altitudes were the one with highest errors.

    This solar resource was used as well as temperatures and installed PV capacities to model the entire PV production fleet of the island. Different models were tested using a representative PV installation for the entire island and its parameters were adjusted to fit the real PV power production of 2018. The model with the lowest relative RMSE for power comparison uses only efficiency, tilt and orientation angles with installed PV capacities gathered at each 63kV/15kV transformer’s zone to reach a relative RMSE of 14.3%.

    Using this model, the algorithm was developed to size PV production fleet, PHES and Li-ion batteries capacities for a given desired production profile. Different production profiles were tested to cover from 10% to 100% of the total electricity demand of the Reunion Island in 2030 with different profile’s shapes. For each of these profiles, best configuration was chosen by minimizing the LCOE resulting in a range from 14.8c/kWh to 22.1c/kWh. Order of magnitude for the different system parts were found to range from 0.5 to 5 GW for PV, 2 to 37 GWh for PHES and 3 to 70 MWh for Li-ion batteries. In some cases, curtailed energy could serve to cover the annual consumption of 44 000 hydrogen cars or the half of 2018 water consumption by using desalinization. Profiles to replace fossil fuels power production were tested and a 100% renewable mix could be achieved with 4 GW of PV, 27 GWh of PHES and 50 MWh of Li-ion batteries for a LCOE of 19.8c/kWh. This profile allows dividing by almost ten the estimated GHG emissions related to the electricity production in 2030.

    The final conclusion of this study is that variability and uncertainty of solar PV production can be overcome by using overbuilding, curtailment and storage to guarantee a firm power production profile, no matter the desired energy penetration rate and this without increasing the cost of electricity compared to the current mix.

  • Tendolkar, Chaitanya
    KTH, School of Industrial Engineering and Management (ITM).
    An Analysis of Geospatial Factors in Medium Voltage Grid Distribution Network Routing2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To provide electricity access to the population currently deprived of it, is one of the sustainable development goals. Although the number is decreasing and is below 1 billion people without access to electricity for the first time in the year 2017, there is still much to be done. At the current rate of electrification an additional approximately 550 million people of those deprived now would have access to electricity by the year 2030, but 650million would still be without electricity access. This report studies the spatial factors that affect how MV network expansion occurs. The motivation for this report comes from studying previous research work using GIS and studying the Open Source Spatial Electrification Tool (OnSSET) which is developed by the division of Energy Systems Analysis at KTH. The objective of this tool is to aid electrification planning by examining options ranging from national grid expansion to off-grid resources such as solar, wind, hydro based on spatial analysis of data.

    The study is conducted into two parts. First by undertaking a literature review of relevant GIS based electrification and utility planning articles, to identify the factors that contribute to the costs of grid network extension. Thereafter, existing grid networks in Malawi, Nigeria and Uganda have been analyzed to examine the correlation to the different factors identified in the literature review. A qualitative comparison is conducted between the different countries to aid the development of spatial analysis tools such as OnSSET.

    The observations made studying the countries in the Sub-Saharan Africa region are noted down in the results section depicting similarities in planning and implementation of the grid network. Finally, necessary suggestions are made that might supplement and help the efforts in geospatial electrification network planning tools like OnSSET. The differences between literature review and practical geospatial analysis tools is also mentioned including the challenges faced during this thesis.

  • Emilsson, Arvid
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Buhrgard, Andreas
    KTH, School of Industrial Engineering and Management (ITM).
    Towards a prototype of a modular biogas system2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As of today, large unused potential for biogas production exist within the Swedish agriculture sector. The biogas production within this sector is, however, associated with several problems such as poor energy efficiency and non-profitable systems. This is to some degree due to lack of standardized technical solutions. International Micro BioGas AB (IMB AB) has been aided by KTH since 2014. This project investigates several innovations from IMB AB in regards to biogas production:

    ÔĀ∂ A mixing device

    ÔĀ∂ A building capturing waste heat from the digesters (building concept)

    ÔĀ∂ Insulation of the digester (cover concept)

    ÔĀ∂ Small-scale and modular package systems

    The innovations listed above are evaluated from energy, economic and environmental perspectives by doing a case study on the dairy farm Ogestad close to Gamleby, Sweden. Two cases are considered. In Case 1, the raw biogas is burned in a combined heat and power-unit (CHP) in order to produce electricity. In Case 2, raw biogas is upgraded in a small-scale upgrading unit to vehicle gas standards which is sold to the market.

    The results show that the mixing device is promising in terms of energy use. It is therefore recommended to move on with testing of the equipment. The cover concept and the building concept show similar performance from energy and environmental standpoints. The building concept is concluded not to be economically viable. The cost reduction by applying a modular concept where one product can be used on different sized farms is significant. However, the needed investment from the company is large. The goal of achieving a modular system is therefore concluded desirable. The subsidy from the Swedish board of agriculture covering 40 % of the investment cost, has a major impact on the profitability of the systems. Without this subsidy, the systems are not viable in terms of economy. In Sweden, the small-scale vehicle gas production (Case 2) was concluded the most profitable as well as the best-performing from energy and environmental standpoints.