| 1. |
- Böckin, Daniel, 1989
(författare)
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Towards empirically grounded guidance for resource efficiency: Applying, developing and synthesising environmental assessments
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Numerous solutions have been proposed to mitigate environmental damage, including resource efficiency and the vision of circular economy. Suggested solutions are often formulated as guidelines and heuristics like in the EU waste hierarchy, so-called R-hierarchies for resource efficiency and various guidelines for circular business models. However, these are often formulated on a conceptual basis without empirical support. Hence, it is often unclear in what contexts they are valid and how they can be interpreted for different types of products and applications. Systemic environmental assessments are necessary, and have been widely employed, to provide more solid empirical support for guidelines and for investigating the efficacy of suggested solutions. There is also a need for the results and learnings of those assessments to be easily understandable and usable for guiding decision-making towards reducing environmental impact within, say, product design and business management. The purpose of this dissertation is to 1) formulate empirically grounded guidelines for resource efficiency and 2) test existing guidelines and heuristics in specific cases. The first aim is addressed by synthesising assessments of resource efficiency measures in literature. This revealed in what circumstances each measure can yield environmental benefits, depending on product characteristics, as well as when there are possible trade-offs and limitations. Several product characteristics were identified as of key importance for the efficacy of measures, including whether products are durable or consumable, active or passive, used for their full technical lifetime, used frequently or not and finally the product’s complexity and pace of development. The second aim is addressed by carrying out a prospective life cycle assessment (LCA) scrutinising the expectations of metal 3D printing for reducing automotive environmental impacts. The results showed that 3D printing can potentially reduce future life cycle impacts, by allowing redesign of components for lower weight and thus lower fuel consumption. However, this is only valid with low-fossil electricity for the printing process and developments towards printing with low-impact materials like low-alloy steel. The second aim is further addressed by testing the potential environmental benefits of alternative business models. The method business model LCA method (BM-LCA) was developed for this purpose, taking the business itself as the object of analysis. The method uses economic performance as the basis of comparison, thus allowing a business to calculate the environmental consequences of business decisions. BM-LCA was applied to an apparel company, comparing selling and renting jackets. The results show that renting enabled sustained economic performance while reducing environmental impacts. This depended, however, on the sustainability of the transport and energy systems, as well as on business model parameters like price and rental efficiency, and on customer habits. This dissertation shows that environmental assessments can be used to provide an empirical foundation for improved resource efficiency guidelines and to test the validity of heuristics Two key contributions and innovations are emphasised. The first is the formulation of empirically grounded guidelines based on key product characteristics. The second is the formulation and testing of BM-LCA, a method for assessing decoupling business from environmental impact.
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| 2. |
- Engström, Rebecka Ericsdotter, 1984-
(författare)
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Exploring cross-resource impacts of urban sustainability measures : an urban climate-land-energy-water nexus analysis
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In an increasingly urban world, cities' global resource uses grow. Two fundamental resources for making cities liveable are water and energy. These resources are also closely interlinked – systems that convert and deliver energy to cities require water, and urban water systems use energy. In addition, these two resource systems affect and are affected by land use and climate change. This ‘nexus’ between climate, land use, energy and water (CLEW) systems has been extensively studied in the past decade, mainly with a focus on national and transboundary CLEW systems. This doctoral thesis develops the CLEW nexus research from an urban perspective.Two quantitative analyses examine how different types of sustainability measures in cities affect intended and unintended CLEW systems. First, the CLEW impacts of a set of sustainability measures in New York City are assessed - from water conservation to emission reductions. Results show that every measure affects (to varying degrees) all studied sustainability dimensions - water, energy and climate - and that the impacts can be quantified through a reference-resource-to-service-system (RRSS).The second quantitative study focuses on how CLEW impacts from a city's sustainability efforts spread beyond local and international borders. It investigates how global water and land use are affected in alternative scenarios to achieve climate neutrality in 2030 in the town of Oskarshamn, Sweden, using an energy systems simulation model. The study finds that both the magnitude and the geographical distribution of land and water requirements vary between scenarios. A strategy to achieve climate neutrality that invests in electrification leads to increased national water use, while a strategy that relies on biofuels has a greater impact on water and land use internationally. When results are translated to interactions between the UN's sustainable development goals (SDGs), they reveal that SDG synergies and trade-offs are 'strategy-dependent': different options for achieving SDGs on energy, sustainable cities and climate action have varying consequences for the advancement of SDGs on sustainable water, food production and biodiversity.To shed light on how data challenges affect quantitative urban nexus studies, uncertainty assessments of selected thesis’ results are conducted and complemented with a thematic analysis of a set of recently published urban nexus papers. Together, they indicate that analytical choices, uncertainties in results and - as a consequence - research foci are influenced by data limitations in both this thesis and in other urban nexus studies.Lastly, the finding from the Oskarshamn analysis – that SDG interactions are strategy-dependent – is deliberated with experts within sustainability sciences and SDG interaction research. From this, a research agenda is proposed with measures to make SDG 'spillovers' visible in local level decision-making.Taken together, the thesis contributes to filling several knowledge gaps on how urban sustainability measures within the CLEW systems interact within and beyond city limits, and proposes analytical approaches to quantify these interactions. It further points out how current data challenges constrain quantitative urban nexus analyses and highlights research needs to improve data management as well as other key efforts to enable consideration of nexus interactions, including SDG 'spillovers', in cities' sustainability work.
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| 3. |
- Modaresi, Roja, 1982
(författare)
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Dynamics of aluminum use in the global passenger car system: Challenges and solutions of recycling and material substitution
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis analyzes the relationship between the design of vehicles, end-of-life vehicle (ELV) management, and global material production using aluminum as an example. Vehicle manufacturing, material industries and ELV management face different challenges. An important challenge for vehicle manufacturers is the design of lightweight vehicles to reduce energy use and greenhouse gas (GHG) emissions in the use phase for which an increased use of aluminum of different alloys is an attractive option. The aluminum industry has an interest in reducing energy consumption and GHG emissions, which can be accomplished effectively through recycling. ELV management must be improved to enable the first two systems to use aluminum scrap in a sustainable manner. Today, the sorting of different alloys is limited. As a result of having mixed scrap at the ELV phase and limited opportunities for aluminum refining, there may be a future scrap surplus that cannot be absorbed by the aluminum-recycling sink, which is passenger cars. These three sectors are connected through material flows, and a change in one of the sectors can severely affect the others' options for reaching their goals. This thesis addresses the following questions: 1) How are the dynamics of the global vehicle stock changing the boundary condition for aluminum recycling? 2) What are the most effective interventions to minimize a future aluminum scrap surplus? 3) What are the options for material substitution in vehicles to reduce direct and indirect GHG emissions over time? To answer these questions, a system approach is employed to analyze how these three sectors are linked and to explore options for all sectors to reach their objectives in the long term. This thesis employs global bottom-up stock-driven models of the aluminum cycle. A basic model was used to identify the scrap surplus problem. A refined model with segments, components and alloys resolution combined with a source-sink diagram was used to evaluate different solution options. In addition, a global dynamic fleetrecycling MFA model was developed to simulate the future impacts of material substitutions of conventional steel with high-strength steel (HSS) and aluminum on material cycles, energy use and GHG emissions related to the global passenger vehicle fleet. The main findings in this thesis are: i) a continuation of the current practice of cascadic use would eventually result in a scrap surplus because this practice depends on the continuous and fast growth of the secondary casting stock in the global vehicle fleet, a condition that is unlikely to be met. Model simulation indicated a non-recyclable scrap surplus by approximately 2018±5 if no alloy sorting is introduced. The surplus is potentially substantial and could grow to reach a level of 0.4-2 kg/cap/yr by 2050, thereby significantly reducing the option of the aluminum industry to reduce its energy consumption through recycling. ii) Drastic changes in ELV management practices are necessary to make use of the growing scrap flow in the future, including further dismantling and efficient component-to-component recycling, alloy sorting of mixed shredded scrap, and designing recycling-friendly alloys that function as alternative sinks for aluminum scrap. iii) Light-weighting has the potential to substantially reduce global emissions of vehicles (9-18 gigatons cumulative CO2-eq. between 2010 and 2050). In the medium term (5-15 years), global emissions reductions from substituting standard steel with aluminum are similar to those achievable by HSS; however, over a longer term (after 15-20 years), substitution with aluminum can reduce total emissions more effectively, provided that the wrought aluminum will be recycled back into automotive wrought aluminum. The environmental consequences of products in general and passenger cars in particular have led to an increasing awareness of the dependencies between the shaping of vehicles and the shaping of the environment. Governments and intergovernmental bodies have formulated quality goals for the environment, such as the 2-degree target, and have introduced emissions standards, thereby extending the responsibility of automobile manufacturers to the use phase. On the materials side, legislation has been introduced to extend producer responsibility, mainly with the goal of avoiding toxic substances and reducing the amount of waste, as is noted in different end-of-life vehicle (ELV) legislation and directives. The current ELV directives do not sufficiently address the management of material systems as a whole or quality issues related to material recovery. To harmonize ELV management with goals for the global aluminum cycle and its impacts for the environment, it is essential to understand how the above-mentioned systems interact. Has parts Paper 1: Modaresi, Roja; Müller, Daniel B.. The Role of Automobiles for the Future of Aluminum Recycling. Environmental Science and Technology 2012 ;Volum 46.(16) s. 8587-8594 http://dx.doi.org/10.1021/es300648w Copyright © 2012 American Chemical Society Paper 2: Rombach, Georg; Modaresi, Roja; Müller, Daniel B.. Aluminium Recycling- Raw Material Supply from a Volume and Quality Constraint System. World of Metallurgy - ERZMETALL 2012 ;Volum 65.(3) s. 157-162 Paper 3: Modaresi, Roja; Løvik, Amund Nordli; Müller, Daniel Beat. Component- and Alloy-Specific Modeling for Evaluating Aluminum Recycling Strategies for Vehicles. JOM: The Member Journal of TMS 2014 ;Volum 66.(11) s. 2262-2271., The article is not included due to copyright available at http://dx.doi.org/10.1007/s11837-014-0900-8 Paper 4: Løvik, Amund Nordli; Modaresi, Roja; Müller, Daniel Beat. Long-term strategies for increased recycling of automotive aluminum and its alloying elements. Environmental Science and Technology 2014 ;Volum 48.(8) s. 4257-4265 http://dx.doi.org/10.1021/es405604g Copyright © 2014 American Chemical Society Paper 5: Modaresi, Roja; Pauliuk, Stefan; Løvik, Amund Nordli; Müller, Daniel Beat. Global Carbon Benefits of Material Substitution in Passenger Cars until 2050 and the Impact on the Steel and Aluminum Industries. Environmental Science and Technology 2014 ;Volum 48. s. 10776-10784 http://dx.doi.org/10.1021/es502930w Copyright © 2014 American Chemical Society Publisher NTNU Series Doctoral thesis at NTNU;2015:116
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| 4. |
- Nordelöf, Anders, 1975
(författare)
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Using life cycle assessment to support the development of electrified road vehicles. Component data models, methodology recommendations and technology advice for minimizing environmental impact
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The anthropogenic pressure on the Earth system already overshoots safe limits for climate change, so there is an urgent need to drastically reduce greenhouse gas emissions caused by transportation. Electric propulsion technology is a promising solution that can decouple fossil fuel use from road vehicle traffic. Additional benefits include removed tailpipe exhaust gas emissions, which currently damage human health and the environment, both locally and regionally.However, electrification of vehicles could lead to problem shifts, e.g. from the use of fossil fuels to the generation of fossil electricity. Even when combined with renewable energy, there are trade-offs between benefits in operation and added environmental load during manufacturing, shifting from airborne emissions to resource related impacts. This is because electric powertrain components require new materials and more advanced processing compared to conventional vehicle parts.The environmental impacts of vehicle electrification can be analyzed using life cycle assessment (LCA). This is a holistic systems tool, where all life cycle stages, from raw material acquisition to disposal, are investigated for potential contribution to environmental problems. For LCA of vehicles, a well-to-wheels study examines the life cycle of the energy carrier, i.e. a fuel or electricity, whereas complete LCA includes the production, use and disposal of the vehicle as such. A thorough review of the research field exposed short-comings in both methodology and inventory data.This thesis aims to discuss in what ways LCA support the development of electrified road vehicles, and present contributions on how the methodology can advance to provide better support, with the goal to minimize environmental impact of vehicles in the long term.Two component data models were developed. These estimate the mass and composition of one electrical traction motor and one inverter unit (the motor controller), calculate full gate-to-gate manufacturing inventories, and point to an existing database to establish cradle-to-gate models. Both are scalable from basic engineering parameters, build on typical design solutions and are easy-to-use. During this work, 45 new unit process datasets for manufacturing were compiled and the thesis discusses and presents useful strategies for data collection.A critical review of 79 publications was conducted. It was found that most LCA studies of electric vehicles fail to report their purpose and time scope as required by the ISO standard for LCA, making results appear divergent and creating a demand for more restrictive LCA guidelines to enhance comparability. But LCA has utility beyond comparing electric and conventional vehicles, e.g. to guide stepwise improvements in design and manufacturing. Such studies address a technical audience rather than consumers or policy makers. An LCA study in the project evaluated three electric motors with different designs and magnets. Results show that the making of aluminum, electrical steel and copper dominates the environmental load of the production. In particular, copper use is a driver of toxic impacts.The thesis stresses the importance of framing LCA studies to advise specific actors to take action and avoid future environmental impact. The thesis advises policy makers, automotive and power industries to plan and act for a conjoint development of electrified vehicles with fossil free electricity production, to attain the full climate change mitigation potential of electrification. Policy makers and automotive industries need to be aware that energy efficiency is key to low impact, while the equipment production, especially of primary metals and related toxic emissions, becomes increasingly important.
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| 5. |
- Paramonova, Svetlana, 1986-
(författare)
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Re-viewing industrial energy-efficiency improvement using a widened system boundary
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Improved energy efficiency in industry is important for reaching the targets within the EU strategy for increased sustainability. However, energy efficiency is not always prioritised within companies, and the improvement potential remains large. This paradox called an energyefficiency gap is explained by energy-efficiency barriers. The low interest in energy efficiency is also explained by the fact that it is not within companies’ core competences and not perceived as strategic. The public policies aiming at closing the gap have thus far been concentrated on the faster diffusion of energy-efficient technologies. This is not sufficient, and the gap can be extended by including energy management practices. To bridge the extended gap, there is a need to introduce an extended system perspective. The aim of this thesis is to investigate the industrial energy-efficiency potential and possibilities for reaching this potential using an extended system boundary.In this thesis, the extended gap was quantified by means of classification of the energy data covering the most electricity-intensive Swedish industrial companies. The results show that technology-related measures represent 61% of energy savings, whereas management-related measures account for 38%. Energy efficiency due to management-related measures can be improved with lower costs. The energy-efficiency potentials for different levels of industrial motor systems were quantified, showing that the highest potential is found in the measures that include personal involvement and the optimisation of routines. This proves that the general approaches based on technological diffusion seem to not be sufficient to solve the energy paradox.The evaluation of the Swedish energy audit programme for small and medium-sized enterprises (SMEs) proved that there is a lack of energy-related knowledge among SMEs. The implementation rate of measures proposed in the audits is only 54%, while there is also a need to reach the SMEs not covered by the programme. The international study of energy-efficiency potentials did not indicate energy management to be considered by SMEs at all.To bridge the extended gap, the external experts’ knowledge on how to work with energy efficiency has to stay within companies. For this, there is a need for methods based on longterm orientation as well as a systematic view of complicated processes. The methods should be universal and applied in a particular context. An example of such a method for large industries is presented in this thesis, whereas applying it to SMEs is problematic due to limited resources. Participating in networks for energy efficiency can be a way to initiate energy-efficiency work within SMEs on a continuous basis. Moreover, this thesis shows that there is a need for the development of a common taxonomy for energy data as well as the development of a central portal where energy data can be reported and stored. This would simplify the monitoring of energy end-use, the control of measures implementation and the comparison between processes, companies and sectors.
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| 6. |
- Pereira Ramos, Eunice, 1982-
(författare)
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Advancing Nexus Approaches: insights from practice in support of their operationalisation
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The last decade has seen the emergence of a new research theme - the study of the resources Nexus. The “Nexus” refers to considering the functioning of several systems simultaneously, as opposed to one, as the object of research. This perspective reasons that coherent decision-making needs to consider systems' interconnectedness. Typical system-of-systems (Nexus) studied relate to the security of services, such as the Water-Energy and Food Nexus, and resources, i.e. the Climate, Land, Energy and Water systems (CLEWs) Nexus. The process of examining cross-systems dynamics and interactions is known as the Nexus approach. Implementing it requires understanding multiple systems, disciplinary integration, and multi-stakeholder engagement at various decision levels. Adequate planning of an assessment process is needed to ensure the successful implementation of the approach and its long-lasting presence in decision-making processes. Therefore, reviewing the application of Nexus approaches can inform essential aspects that clarify and streamline the entire process. Current gaps in Nexus research include the lack of clarity in systems representation, the lack of flexible and accessible tools and methods for Nexus analyses, and the need for transparency in modelling approaches. All of these hinder the integration of the approach in research and the incorporation into decision-making processes. The thesis aims to advance the science of integrated resource assessments, particularly the Nexus approach, and support its dissemination and implementation within and beyond academia. Insights from applying two Nexus approaches (CLEWs and SIM4NEXUS) are distilled from the comparison of case studies. Overarching aspects examined include the expertise engaged in assessments, practitioners' roles and transdisciplinarity. Also analysed are selected components in the Nexus approach, such as identifying systems' interactions, analytical approaches, and stakeholder engagement and participation. The transversal feature of knowledge transfer between experts, practitioners, and stakeholders is examined to understand its importance in the assessment process. Examples of quantitative analyses illustrate the representation of different Nexus contexts and the elaboration of relevant insights. This thesis presents two such quantitative examples. One example is an entry-level CLEWs modelling exercise, whose development is described from conceptualisation, model development, and interpretation of results. The other example is a quantitative analysis of the transboundary Syr Darya river basin, which investigates the role of model structure in exploring Nexus questions. The thesis highlights a list of principles to support the Nexus approach's operationalisation deriving from practice and considering current research gaps.
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| 7. |
- Brynolf, Selma, 1984
(författare)
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Environmental assessment of present and future marine fuels
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Our globalised world is connected by shipping, an industry powered by one of heaviest and dirtiest products of refining: heavy fuel oil. Tougher environmental regulations are now challenging the industry to take action. Ship-owners and operators are faced with the choice of installing exhaust gas cleaning technologies or switching to a different fuel altogether. The primary purpose of this thesis was to assess the environmental performance of present and future marine fuels and to evaluate potential methods and tools for their assessment.Two different system approaches are used in this study: life cycle assessment (LCA) and global energy systems modelling. LCA is a well-established method for assessing the environmental performance of fuels. This type of assessment was complemented with the use of the Global Energy Transition (GET) model to investigate cost-effective fuel choices based on a global stabilisation of CO2 emissions and the global competition for primary energy sources. The GET model includes all energy sectors and considers the interactions among them, but it is limited in scope to CO2 emissions and costs. The LCAs involve a holistic systems perspective that includes the entire life cycle and various types of environmental impacts, but they are limited to analyses of one product or service at a time. These methods provide insights that are both contradictory and complementary.This study concludes that there is substantial potential for reducing the environmental impact of shipping through a change in fuel types and/or the use of exhaust abatement technologies. A switch from heavy fuel oil to any of the alternatives investigated in this study reduces the overall environmental impact of marine fuels. The GET model indicates that it is cost-effective to phase out the use of crude oil-based fuels in the shipping sector and replace these fuels with the use of natural gas-based fuels during the next few decades. Based on the LCA results, the use of biofuels may be one possible way to reduce the impact of shipping on the climate, but biofuels may only be a cost-effective fuel in shipping if the corresponding annual available bioenergy resources are sufficiently large. Three important implications are highlighted: the importance of reducing the NOX emissions from marine engines, the need to regulate the methane slip from gas engines and the fact that a change in fuels may not reduce the impact of shipping on the climate.
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| 8. |
- Murekatete, Rachel Mundeli, 1981-
(författare)
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Sensitivity, Variation, and Application of Least-Cost Path Models in Landscape Connectivity Analysis and Corridor Planning
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent decades, Rwanda has been affected by the loss and fragmentation of natural habitats for native species of animals and plants. As a consequence, landscape connectivity—i.e., the degree to which a landscape facilitates or impedes the movement of organisms between resource patches—has considerably weakened or is even completely lost, causing detrimental effects on biodiversity, notably the reduction of populations of key native species. In order to counter this problem, one potential solution currently being explored by local planners in Rwanda consists of establishing conservation corridors for organisms to move safely between their habitat remnants. Specifically, this thesis was inspired by a project initiated by the Dian Fossey Gorilla Fund International, a conservation non-governmental organization (NGO) based in Rwanda, which consists of establishing a conservation corridor for pollinators.For their capabilities of storing, processing, and visualizing landscape data, geographic information systems (GIS) have been increasingly popular among conservation biologists and practitioners. Of particular relevance to connectivity analysis and corridor planning is the least-cost path model. A typical use of this model is such that one first estimates the cost for a certain action (e.g., movement by an organism or acquisition by a government) at each location of a given landscape and represents the results in the form of a raster surface, and then measures the degrees of connectivity between patches of interest in terms of effective distances, which are equated with least-cost path distances over the raster cost surface. While the least-cost path model is easy to use and available in virtually any commercial raster-based GIS, we observe that users of it often overlook some important assumptions, the violation of which might greatly affect the validity of the model’s outcome.The goal of this thesis is to provide a scientific contribution to landscape connectivity analysis and conservation corridor planning by 1) investigating the potential misuse or abuse of the conventional least-cost path model when sufficient information is not available on the underlying cost surface, 2) proposing an alternative model under such a circumstance and 3) demonstrating its relevance to conservation practice. More specifically, for the model to work, it is explicitly or implicitly assumed that, the optimality of a path is evaluated as the sum of the cost-weighted lengths of all its segments—cost-weighted, i.e., multiplied by their underlying cost values. The validity of this assumption must be questioned, however, if cost values are measured on a scale—e.g., an ordinal scale of measurement in Stevens’s typology—that does not permit arithmetic operations. In a typical practice of landscape connectivity analysis and corridor planning, the raster cost surface is created by transforming one or more sets of values (e.g., land cover type, land ownership, and elevation) attributed to cells into another set of such values (representing cost) through a function reflecting one or more criteria. A question arises: how certain can one be about the correctness of such a cost estimation function?There are at least four issues in the application of the least-cost path model to landscape connectivity analysis and corridor planning under uncertainty. First, while it is generally anticipated that different cost estimation functions lead to different least-cost paths (hence to different effective distances or different corridor locations), little is known on how such differences arise (or do not arise). Second, while it is generally recognized that the location and length of a least-cost path are both sensitive to the spatial resolution of the raster cost surface, little is known if they are always sensitive in the same way and to the same degree and if not, what makes them more (or less) sensitive. Third, when it is difficult to establish a fully connected corridor between target habitat areas (e.g., because of surrounding anthropogenic activities), the least-cost path (which is by definition fully connected) may not be useful at least in its original form. Lastly, even if the conventional least-cost path model may have inconsistent results in theory, it may well be continued to be used in practice, unless there is a sound alternative to it.The issues raised above are addressed through four studies corresponding to four respective papers which are appended to this thesis. While the first three studies use artificial landscape data generated by computers with varying spatial and non-spatial characteristics, the fourth study uses data on a real landscape. The first study (Paper 1) evaluates how the locations and lengths of least-cost paths (the latter of which are referred to as least-cost distances) vary with change in cost estimation parameters. This is done through a series of computational experiments, in which each of the artificial landscapes is converted into different cost surfaces by systematically varying parameters of a cost-estimation function, on which least-cost paths are generated. The locations and lengths of those paths are statistically analyzed to find sources of their variation. The second study (Paper 2) investigates how the least-cost distance is affected by the spatial resolution of the corresponding cost surface. This is also done through a series of computational experiments, in which each of the artificial landscapes is converted into a cost surface, which is, in turn, converted into different cost surfaces (different, i.e., only in their spatial resolutions) by systematically aggregating grid cells. Then, the statistical behavior of the ratio of the least-cost distance measured on a lower-resolution cost surface to that measured on a higher-resolution cost surface is analyzed. The third study (Paper 3) proposes the mini-max path model as an alternative to the least-cost path model. Unlike the conventional model (in which the optimality of a path is based on the sum of its length multiplied by the underlying cost values), the alternative model determines the optimality of a path using the length of a segment(s) of the path that intersects the cells having the maximum cost value (with a special tie-breaking rule). The performances of the two models are tested in one of the following two assumptions at a time: the cost values are measured on an ordinal scale or on a ratio scale. The fourth study (Paper 4) applies the model proposed in the third study to an ongoing conservation project of the Dian Fossey Gorilla Fund International that plans to design a ‘stepping-stone’ corridor—which is not fully connected but takes the form of a sequence of fragmented forest patches—between two core habitat areas of pollinator birds between two protected areas in Rwanda. The project does not have complete information on the study area and the target species and thus the project staff can only rank land cover types in terms of their suitability/cost for being part of the corridor. The utility of the model is tested with different assumptions on the behavior of the birds (e.g., minimum stepping stone size) as well as on the cost associated with the implementation of the corridor (e.g., cost for planting shrubs along the corridor to encourage the birds to use it).The first study finds that the same pair of terminal cells may well be connected by different least-cost paths on different cost surfaces though derived from the same landscape data. The variation among those paths is highly sensitive to the forms of spatial and non-spatial distributions of landscape elements (which cannot be controlled by users of the least-cost path model) as well as by those of cost values derived from them (which may be, at least indirectly, controlled by users of the model). The second study finds that least-cost distances measured on lower-resolution cost surfaces are generally highly correlated with—and useful predictors of—effective distances measured on higher-resolution cost surfaces. This relationship tends to be weakened when linear barriers to connectivity (e.g., roads and rivers) exist, but strengthened as distances increase and/or when linear barriers (if any) are detected by other presumably more accessible and affordable sources such as vector line data. The third study confirms the effectiveness of the conventional least-cost path model on ratio-scaled cost surfaces but finds that the alternative mini-max path model is mathematically sounder if the cost values are measured on an ordinal scale and practically useful if the problem is concerned not with the minimization of cost but with the maximization of some desirable condition such as suitability. The fourth study demonstrates the utility of the mini-max path model by effectively casting the stepping stone corridor problem as a special case of it. The model allows for a rapid first delineation of candidate routes for stepping stone corridors and facilitates the early exploratory stages of conservation projects.Major implications of this thesis to the research and practice in landscape connectivity analysis and conservation corridor planning with raster-based GIS are summarized as follows.When sufficient information is available for quantification of cost values, the conventional least-cost path model is a reasonable approach to use.However, it is worth trying or at least acknowledging alternatives that do not rely on the quantitative-cost assumption if the value of each cell only indicates the ordinal category of cost of intersecting that cell. Note in particular that information used for cost estimation in practice (e.g., expert opinions or public surveys) are often of subjective and qualitative nature.The highest-resolution data may not always be most effective—much less, most cost-effective—for the task being undertaken. The choice of spatial resolution of th
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| 9. |
- Ajdari, Sima, 1985
(författare)
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Chemistry and Process Design of Integrated Removal of Nitrogen and Sulfur oxides in Pressurized Flue Gas Systems
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carbon capture and storage is vital to reach the climate goals to limit the increase in the global temperature. Among the carbon capture technologies, oxy-fuel and chemical looping combustion produce a stream mainly containing carbon dioxide (CO2) and water but also contaminants such as nitrogen oxides (NOx) and sulfur oxides (SOx). The carbon dioxide is compressed and separated from water and impurities to achieve suitable conditions for transport and storage. In addition to storage and transport system requirements, separation of NOx and SOx during the CO2-conditioning is required to avoid corrosion issues in various parts of the process. In addition to the emission control measures available for conventional power plants, there are new opportunities for control of NOx and SOx in pressurized flue gas systems of oxy-fuel and chemical looping combustion plants. The work presented in this thesis evaluates the chemistry and process design of NOx and SOx removal during CO2-conditioning in oxy-fuel and chemical looping combustion systems. The primary goals of this thesis are to expand the current understanding of NOx and SOx chemistry and identify favorable conditions for achieving cost-effective control processes. Analysis of the reaction system by a detailed chemistry model, uncovers the importance of pH level in the liquid for the selectivity of the integrated NOx and SOx removal process. Moreover, a reduced mechanism is proposed for engineering calculations of the pressurized flue gas systems that captures the effect of pH and describes the relevant gas and liquid-phase chemistry. Process simulations, which utilize the reduced mechanism, enable evaluation of design of the integrated removal of NOx and SOx in pressurized flue gas systems. Technical evaluation of the integrated process reveals that removal rates of >98% for SO2 and >90% for NOx may be achieved. Moreover, the efficiency of the NOx removal can be improved by the presence of SOx and increased concentration of O2 in the flue gas. A comparison of the economic performance of the integrated removal process and the conventional emission control measures, i.e., selective catalytic reduction and wet flue gas desulfurization with limestone, shows significantly lower costs of removal by the integrated process.
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| 10. |
- Laurenti, Rafael, 1980-
(författare)
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The Karma of Products : Exploring the Causality of Environmental Pressure with Causal Loop Diagram and Environmental Footprint
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Environmental pressures from consumer products and mechanisms of predetermination were examined in this thesis using causal loop diagram (CLD) and life cycle assessment (LCA) footprinting to respectively illustrate and provide some indicators about these mechanisms. Theoretical arguments and their practical implications were subjected to qualitative and quantitative analysis, using secondary and primary data. A study integrating theories from various research fields indicated that combining product-service system offerings and environmental policy instruments can be a salient aspect of the system change required for decoupling economic growth from consumption and environmental impacts. In a related study, modes of system behaviour identified were related to some pervasive sustainability challenges to the design of electronic products. This showed that because of consumption and investment dynamics, directing consumers to buy more expensive products in order to restrict their availability of money and avoid increased consumption will not necessarily decrease the total negative burden of consumption. In a study examining product systems, those of washing machines and passenger cars were modelled to identify variables causing environmental impacts through feedback loops, but left outside the scope of LCA studies. These variables can be considered in LCAs through scenario and sensitivity analysis. The carbon, water and energy footprint of leather processing technologies was measured in a study on 12 tanneries in seven countries, for which collection of primary data (even with narrow systems boundaries) proved to be very challenging. Moreover, there were wide variations in the primary data from different tanneries, demonstrating that secondary data should be used with caution in LCA of leather products. A study examining pre-consumer waste developed a footprint metric capable of improving knowledge and awareness among producers and consumers about the total waste generated in the course of producing products. The metric was tested on 10 generic consumer goods and showed that quantities, types and sources of waste generation can differ quite radically between product groups. This revealed a need for standardised ways to convey the environmental and scale of significance of waste types and for an international standard procedure for quantification and communication of product waste footprint. Finally, a planning framework was developed to facilitate inclusion of unintended environmental consequences when devising improvement actions. The results as a whole illustrate the quality and relevance of CLD; the problems with using secondary data in LCA studies; difficulties in acquiring primary data; a need for improved waste declaration in LCA and a standardised procedure for calculation and communication of the waste footprint of products; and systems change opportunities for product engineers, designers and policy makers.
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