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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Circular economy in the Nordic region – on the right path? : The effect of circular economy business practices on firms’ environmental performance

Horikx, Lotte, Beqiri, Bledar January 2017 (has links)
Over the last couple of decades, sustainability has gained importance in the business world, and a concept that has often been used as a prime example of how to deal with today’s environmental problems is circular economy. Even though the topic is relatively new, there has already been quite some debate about its actual advantages and disadvantages, and while there is as of yet no consensus, the majority argues that the application of circular economy practices will be beneficial for the environment. Which is exactly what this research has attempted to ascertain by looking at 78 firms from a wide range of industries yet all from the Nordic region, since this geographical area has been hailed repeatedly for their sustainability. This was done by performing a hierarchical regression analysis on the data in order to explore a possible relationship between the score of a firm on the benchmark of circular economy practices and its corresponding environmental performance, specifically energy consumption, water usage and greenhouse gas emissions. The hierarchical regression analysis showed a significantly positive relationship between a firm’s score on the benchmark of circular economy practices and its energy consumption, while controlling for firm size, industry, debt ratio,slack resources and country of origin, which was contrary to expectations. No such relationship was found between a firm’s benchmark score and their water usage, the same goes for greenhouse gas emissions. Nevertheless, this research has taken an important step in understanding the relationship between circular economy practices and a firm’s environmental performance, and in doing so has opened up new avenues to explore in terms of future research. While the Nordic region is on the right track, there is still a long road ahead.
112

Catalytic Upgrading of Biogas to Fuels: Role of Reforming Temperature, Oxidation Feeds, and Contaminants

Elsayed, Nada 23 January 2017 (has links)
Global energy demands are constantly increasing and fossil fuels are a finite resource. The shift towards alternative, more renewable and sustainable fuels is inevitable. Furthermore, the increased emissions of greenhouse gases have forced a pressing need to find cleaner, more environmentally friendly sources of fuel. Biomass energy is a promising alternative fuel because it offers several important advantages. It is a renewable energy form, it comes from many sources and produces biogas (CH4 and CO2). Furthermore, it can have a zero carbon footprint; this is due to the fact that the carbon produced is from the same carbon used to make the biomass. In addition, by replacing fossil fuels, the emissions of CH4 and CO2 (both greenhouse gases) is reduced. Biomass-derived syngas (H2 and CO) can be utilized as a feedstock for many important industrial processes such as methanol synthesis, ammonia synthesis and Fischer-Tropsch synthesis (FTS) to produce long chain hydrocarbon fuels. Municipal solid waste (MSW) biomass is considered as the source of the biomass for this dissertation work. MSW accounts for 20% of man-made methane emissions making it an attractive source for utilization. However, methane reforming to synthesis gas (H2 and CO) typically occurs at temperatures higher than 600°C making it economically challenging at the smaller scale of MSW conversion processes. This dissertation effort focused on formulating low precious metal loaded heterogeneous catalysts that can reform methane at low temperature (T<500°C) making the process more industrially viable. The effect of select contaminants (siloxanes) in the biogas on the reforming catalysts was studied through accelerated poisoning. Finally, the syngas ratio was improved by combining low temperature dry reforming with steam reforming (termed bi-reforming). The catalyst system used for this dissertation study was comprised of 1.34wt%Ni- 1.00wt%Mg on a Ceria-Zirconia oxide support (0.6:0.4 ratio respectively). The catalysts were doped with platinum (0-0.64% by mass) and compared to palladium doped catalysts (0-0.51% by mass). The ratio chosen for the support, Ce0.6Zr0.4, was determined to be the best ratio in terms of activity and surface area by previous studies done in this group [1]. Nickel has been widely studied as methane reforming catalyst [2-6]. Alone, nickel atoms are prone to carbon deposition especially during methane decomposition, however, coupling NiO with MgO helps to reduce carbon deposition by reducing agglomeration of Ni crystallites, thereby improving catalyst lifetime [2, 7]. Furthermore, addition of small amounts of noble metals such as Pt or Pd help to drive the reduction of the catalyst to lower temperatures and enhance catalytic activity. Different metal loadings of Pt and Pd were tested to determine the optimum catalyst that will reform methane at low temperatures, is resistant to deactivation and produces a high syngas ratio (~2:1) which is necessary for processes such as FTS. Preliminary results have shown that in general Pt is superior in this catalyst system for low temperature reforming of methane. It consistently had syngas ratios near the desired ratio compared to Pd, it did not deactivate with extended time on stream and overall had higher turnover frequencies. This catalyst system has potential to make industrial reforming of methane from biomass feedstock more economically viable.
113

Bunker levy schemes for greenhouse gas (GHG) emission reduction in international shipping

Kosmas, Vasileios, Acciaro, Michele 24 September 2020 (has links)
A fuel levy is one of the market-based measures (MBMs) currently under consideration at the International Maritime Organization. MBMs have been proposed to improve the energy efficiency of the shipping sector and reduce its emissions. This paper analyses the economic and environmental implications of two types of levy on shipping bunker fuels by means of an analytical model built on the cobweb theorem. A unit-tax per ton of fuel and an ad-valorem tax, enforced as a percentage of fuel prices, are examined. In both cases, a speed and fuel-consumption reduction equivalent to an improvement in the energy efficiency of the sector would be expected as a result of the regulation enforcement. The speed reduction in the unit-tax case depends on fuel prices and the tax amount, whereas in the ad-valorem case it relies upon the enforced tax percentage. Both schemes lead to industry profit decline, the extent of which depend on the structure of the levy and market conditions. Since there is concern that the costs resulting from the policy will be passed from shipping companies to their customers along the supply chain, the paper dwells on how the costs arising from the enforcement of the levy will be actually allocated between ship-owners and operators, and cargo-owners. In a market characterised by high freight rates and with no or limited excess capacity, a higher percentage of the total tax amount is transferred from ship-owners to shippers. In case of a recession the opposite happens.
114

Towards Climate Neutral Facility Management : Improved Greenhouse Gas Emission Calculations for Ihus

Agerhäll, Isabella, Kindmark, Malin, Stern, Cecilia January 2020 (has links)
Uppsala municipality has set a goal in line with the UN’s 2030 Agenda for sustainable development to be fossil-free by 2030. To achieve this a lot of local companies have signed the Uppsala Climate Protocol. One of these companies is the municipal facility management company AB Uppsala Kommun Industrihus, Ihus. This project aimed to help Ihus map their emissions connected to facility maintenance and management and to enable them to reach their goal of becoming climate neutral by 2030.  The daily facility management was split up into the categories gardening, ventilation and installation, cleaning and facility work, materials and products, renovations, and painting. A sustainability spend analysis was performed on Ihus’ organisation and emissions per spent MSEK were calculated for each category by researching Ihus’ suppliers. By using those emission intensities, the two categories with the highest emissions could be identified as renovations and materials and products with intensities of 84.48 and 57.56 tonnes CO2e/MSEK, respectively. The remaining categories all had intensities below 3 tonnes CO2e/MSEK.  Sensitivity analyses were performed on the results by tweaking the values of which the emissions were based on. The results showed that to lessen Ihus’ climate impact the areas of improvement are life cycle assessments for their facilities and overseeing transports.
115

Analysis of a real-time signal for greenhouse gas emissions of district heating consumption

Reniers, Jorn January 2015 (has links)
The district heating system (DHS) of Stockholm is one of the largest systems in the world with a total yearly production of 10TWh of heat and 2TWh of electricity (through combined heat and power plants). Large amounts of greenhouse gasses (GHG) are emitted to produce this heat and electricity. Given the goal of the City of Stockholm to reduce the amount of GHG emissions to 3 ton per capita in 2015 and to keep reducing emissions at a similar rate after 2015, it is important to identify the potentials for further reductions. Numerous studies have been done on how the DHS can become more sustainable by installing new generation units. However, also the consumers have an influence on the DHS. After all, it are the consumers who decide when and how much heat or electricity they use. Most former studies and environmental guidelines for the DHS in Stockholm focussed on the producer side. This thesis looks at the consumer perspective of the (heat of the) district heating system. A real-time signal giving the greenhouse gas emissions of individual households is developed and its potential and challenges are discussed. With this signal, households that want to minimise their environmental impact have a tool to decrease their environmental impact by changing their consumption. This can be a first step to transform the DHS to a smart district heating system. First, generic models to calculate the dynamic greenhouse gas intensity of the heat production of district heating and to calculate the greenhouse gas emissions related to the heat consumption of households are suggested. Then the feedback signal with those real-time household emissions is calculated for representative households in Stockholm based on data of Stockholm’s DHS and data about hot tap water consumption in Sweden. Results indicate that variations in household level greenhouse gas emissions mostly reflect changes in consumption but can also result from changes by the producer. Intraday variations are mostly caused by changes in hot tap water consumption, while variations on a timescale of a few days are caused by changes in heating consumption (changing weather) and changes made by the producer (to use different fuels). Then several scenarios are calculated, each scenario looking at the actions a consumer can take to shift or reduce his/her consumption (decrease hot tap water usage, lower indoor temperature etc.). The real-time household emissions are calculated again to see if the signal gives the needed incentives (is the household rewarded for its effort? Does it get further incentives?). It was found that a strong time-incentive (to decrease consumption when it saves most emissions) is missing if the average perspective is used to calculate the emission intensity of the heat production. Also, the results confirmed the finding that the feedback signal might not reflect changes in consumption. Finally, challenges for the signal are discussed. One of the major hurdles is the fact that household consumption of heat (heating and hot tap water) can often not be measured on a household level. Thus, it has to be estimated but it seems very difficult to get this estimation accurate enough to give correct feedback to households, especially about the emissions saved by their efforts to reduce/shift their consumption. Secondly, the time resolution should be chosen well to still get accurate results but not make the signal to data-intensive. Finally, the result is heavily dependent on the chosen methodology (average or marginal perspective? Do you account for the electrical side of the DHS? How about the distribution losses? Etc.).
116

Förändrade resemönster i Gävleborgs län : En sammanställning av kostnader och klimatpåverkan vid tjänsteresor samt analys av sociala effekter vid ett skifte mot videkonferens i en organisation / Changed travel patterns in Gävleborgs län : A summary of costs and carbon footprints of business travelling and an analysis of the social effects of a shift towards virtual meetings in an organization

Evers, Erik January 2014 (has links)
The world we live in becomes more globalized as a result of new communication media. Communication occurs over greater distances which leads to increased travel. In the report AR5, by IPCC, it is showed that the human impact of climate change is clear and that something has to be done. Therefore its very important to change the human impact. A part of it is to change the way we travel within the service which leads to the purpose of the thesis. The purpose is to eximine how commune´s, in Gävleborgs län, choice of transport and with a change against virtual meetings affects greenhouse gas emissions and costs. An additional purpose is to gather information about currently known differences between natural and virtual meetings and explain these with a focus on interaction and communication. This is to give information about what it is that makes people feel that virtual meetings lack of communication . This has been done by studying the empirical results of the CERO-model and the NTM-database of greenhouse gas emissions and conduct a literature review relating to projects in the area of virtual meetings and then try to explain their results by learning and communication theories. The results clearly shows that train as vehicle is preferred both environmentally as financially and if the trip must be carried while driving or flying it is only justifiable when trains and public transport is disadvantaged. Virtual meetings are rather cheaper and more environmentally friendly than all vehicles but has some limitations. That is because the conversation becomes formal, and gesticulation and phonological patterns is missing. The restriction of virtual meetings can be explained with that contextual differences arise when individuals meet at great distances while communication requires a stricter meeting posture. / reser inom tjänsten vilket leder till syftet med examensarbetet som är att undersöka hur en kommuns val av färdmedel vid tjänsteresor samt vid ett skifte mot resfria möten påverkar samhället med avseende på växhusgasutsläpp och kostnad. Vidare är syftet att samla information om idag kända skillnader mellan fysiska och resfria möten och förklara dessa med fokus på interaktion och kommunikation. Detta för att ge information om vad det är som gör att en del känner att resfria möten brister i kommunikationen. Detta har gjorts genom att studera empiriska resultat av CERO-modellen och NTMs databas för växthusgasutsläpp samt genomföra en litteraturstudie av projekt inom området resfria möten, för att förklara deras resultat utifrån lärande- och kommunikationsteorier. Resultatet visar tydligt på att tåget som färdmedel både är att fördedra miljömässigt såsom ekonomiskt om resan måste genomföras medan bil och flyg endast är försvarbart då utbredningen av tåg och kollektivtrafik är missgynnad. Resfria möten är istället billigare och miljövänligare än alla färdmedel men har vissa begränsningar då samtalet blir formellt och saknar gestikulering samt fonologiska mönster. Att resfria möten har begränsningar kan förklaras i att kontextuella skillnader uppstår när individer möts på stora avstånd samtidigt som kommunikationen kräver en striktare möteshållning.
117

Benefits of GHG Reduction and Carbon Finance for Adjara project : a case study in Georgia

Tayyeba, Omid January 2009 (has links)
The grave concern over climate change threat and different economic incentives such as the clean development mechanism have given more weight to the potential of projects for reducing greenhouse gas emissions. In Adjara solid waste management project, even though the greenhouse gas reduction was acknowledged, it was not one of the key factors for selecting the most practicable treatment option. In doing so, the study was addressed the benefit of various solid waste treatment methods for Adjara project in terms of greenhousegas emissions reduction. It is followed by analyzing the economic impacts of carbon finance on the financial feasibility of the project according to different economic scenarios. In considering the solid waste treatment technologies that could be suitable for developing countries, seven options were focused in the study: the baseline of open dumping, four options for landfill (no provision of landfill gas capture, landfill gas capture with open flaringsystem, enclosed flaring system and electricity generation), composting and an aerobicdigestion with electricity production. The applicable CDM methodologies were adopted toquantify the amount of reductions for scenarios. Anaerobic digestion scenario had by far thegreatest amount of reduction. In versely, the worst scenario was landfill without landfill gasrecovery which had even more contribution to climate change than the base case. In the economic assessment part, the internal rate of return was adopted as financial indicator and the feasibility study of the project was adjusted according to new economic condition in the presence of carbon finance. The scenario with additional incomes from the sales of both certified emission reductions and electricity maximized the profits of theproject. In case the project partners do not consider the possibility for generating electricity,they can maintain the project’s economic position through the sale of certified emissionreductions instead of the income from selling electricity. These conclusions were tested for uncertainty and sensitivity by modifying the price of the certified emission reductions and the input waste composition and were found to be robust. / <p>www.ima.kth.se</p><p>External cooperation with SWECO</p>
118

LCA of Microgrid System: a Case Study at ‘North-five Islands’ of Changshan Archipelago, China

Yuning, Jiang January 2019 (has links)
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 ‘North-five Islands’ 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 ‘North-five Islands’ 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 – ‘microgrid electricity supply option’, ‘grid extension electricity supply option’, and ‘conventional fossil diesel generators electricity supply option’ are designed to evaluate the life cycle GHG emissions for supplying 20 years electricity demand (362.2 GWh) of the ‘Northfive Islands’. The results show that the life cycle GHG emissions of the ‘microgrid electricity supply option’ are 223.19 million kgCO2eq. Compared to the ‘grid extension electricity supply option’ and ‘conventional fossil diesel generators electricity supply option’, 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 ‘microgrid electricity supply option’ 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’s life cycle GHG emissions. The thesis conducts the sensitivity analysis of diesel burn rate efficiency (L/kWh) of the microgrid system’s 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 ‘North-five Islands’ 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 ‘North-five Islands’ 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.
119

Sustainability demands on internal and external providers of IT

Lenman, Emma, Appelgren, Ida January 2023 (has links)
The use of IT in companies is constantly expanding, and therefore, so is the energy consumption and carbon footprint from IT. If companies do not take steps towards more sustainable IT usage, the footprint will continue to expand, toxic metals will be used in hardware and the usage of world resources will not become more circular. Few studies are made regarding internal and external factors that affect the implementation of sustainable IT. Sustainability is seen as a “core IT objective” by 90% of European IT leaders. There is a knowledge gap concerning internal and external demands within sustainable IT, since no research studies have been found. The aim of this study is to understand what large companies in Sweden do to act more sustainably in their IT usage. What demands are put on suppliers to make more sustainable solutions and which demands are put on employees internally to make their IT usage more sustainable. The research question is: “What external sustainability demands do large companies put on their suppliers of IT systems and hardware, and what internal demands do the companies have on their own IT usage?”. This study will be carried out using survey as a research strategy. Data will be collected from semi-structured interviews with employees from nine different companies as well as the collection of internal documents and documents from the websites of the companies. The data analysis method used is thematic analysis. From the interviews with employees with high knowledge in the companies sustainable IT work, five themes with sixteen different demands were found. Five of the demands were identified as new that previous research has not addressed while the remaining eleven demands can be found in previous research. Some of the demands were repeated no matter how long the company have worked with sustainable IT, such as Recycling hardware, Increasing the life cycle, Involve employees in sustainable IT, Server location and Move to cloud computing. While other demands like System boundaries, Sustainable software development, and Sustainably developed software were more common among more mature companies within sustainable IT. This study found that the two most considerable demands are the external demand Hardware can be recycled and the internal demand Recycling hardware, which implies that circularity has become a more critical topic.
120

Building renovation processes towards low greenhouse gas emissions and energy use

Olsson, Stefan January 2016 (has links)
Buildings from the record year era are now 40 – 55 years old and in many cases in need of extensive renovation measures. This need for renovation could be seen as an opportunity to achieve overarching sustainability target levels and to perform renovation with a holistic approach. This thesis aims at creating support for the formulation and achievement of adequate environmental targets that relate to overarching Swedish Environmental Quality Objectives. The overall aim of the thesis is to contribute to an understanding of the current situation of environmental management in renovation processes. The scope of this thesis is limited to the aspects energy use and greenhouse gas (GHG) emissions from energy use and material production. This thesis contributes to this aim with a stepwise procedure for evaluation of measures together with a proposal for target levels for three environmental aspects. The first paper appended to this thesis investigates how six Swedish property owners performed renovation projects. From this paper it can be concluded that the main barrier (except economic ones) are characterized by lack of knowledge about overarching objectives and what aspects define a sustainable built environment. The second paper assesses embodied GHG emissions due to material production for the totality of measures needed to reduce operational energy demand per unit heated floor area by 50% compared with 1995. On a national level, embodied GHG emissions are estimated to be 12% of the reduction of GHG emissions achieved by operational energy demand reduction. The final paper appended to this thesis uses a case study building to illustrate a working procedure to identify project-specific target levels for three environmental aspects. In addition, it identifies indicative improvements necessary for the achievement of long-term targets for those aspects, which could be focused and further investigated in later project stages with the help of a long-term plan of action. / <p>QC 20160926</p>

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