441 |
Life Cycle Analysis of Greenhouse Gas Emissions from the Mining and Milling of Uranium in Saskatchewan2015 June 1900 (has links)
This thesis presents a detailed study of life cycle greenhouse gas (GHG) emissions intensity during the uranium mining-milling phase of the nuclear fuel cycle for three paired uranium mine-mill operations in northern Saskatchewan (SK). The study period runs from 2006 – 2013 for two of the three pairs, and from 1995-2010 for the third. The life cycle analysis has been conducted based on the ISO 14040:2006 standard using a Process Chain Analysis methodology.
This study differs from previous studies of GHG emissions intensity during the uranium mining-milling phase of the nuclear fuel cycle in two key respects. First, it has a very large system boundary which includes the uranium exploration and mine-mill decommissioning phases. Second, it utilizes a life cycle inventory database to include many processes which would normally fall outside of the system boundary due to their small individual contributions. These differences contribute to a more accurate result.
The production-weighted average life cycle GHG emissions intensity is estimated as 45 kg CO2e/kg U3O8 at an average ore grade of 9.12% U3O8 based on relative U3O8 production volumes at Mine-Mill A, B, and C from 2006 to 2010. The 95% confidence interval for the production-weighted average result ranges from 42 to 49 kg CO2e/kg U3O8, indicating that overall uncertainty in the result is low. Life cycle GHG emission intensity for the three uranium mine-mill pairs are 84, 66, and 35 kg CO2e/kg U3O8 at average ore grades of 0.71%, 1.54%, and 11.5% U3O8 respectively.
Nearly 90% of life cycle GHG emissions are associated with operation of the uranium mine-mills, primarily from energy consumption during operation (69% of total) transport of materials and personnel (7.0%), and use of reagents (5.6%). Remaining processes each individually account for less than 5% of the total.
In calculating emissions from electricity consumption, the base-case emission intensities reported above use a province-wide electricity emission factor because the utility does not differentiate its emissions by region. However, the facilities included in this study are all located in Northern Saskatchewan, which is powered exclusively by hydropower. Application of a regional emission factor reduces the production-weighted average life cycle GHG emission intensity to 26 kg CO2e/kg U3O8 with a 95% confidence interval of 25 to 29 kg CO2e/kg U3O8. This represents a 42% reduction in life cycle GHG emission intensity from the base case.
Due to the high uranium ore grades found in SK uranium deposits, life cycle GHG emissions intensity for uranium from SK is among the lowest in the world. Further, the life cycle GHG emission intensity estimate from uranium mining-milling in SK is a small (approximately 10%) contributor to the life cycle GHG emissions intensity from the nuclear fuel cycle for light water reactors overall, amounting to approximately 1.2 g CO2e/kWh electricity (0.6 g CO2e/kWh electricity calculated using the regional hydroelectric power source).
|
442 |
Techno-economic and Environmental Assessments of Replacing Conventional Fossil Fuels: Oil Sands Industry Case StudiesMcKellar, Jennifer Marie 20 March 2014 (has links)
Conventional fossil fuels are widely used, however there are growing concerns about the security of their supply, volatility in their prices and the environmental impacts of their extraction and use. The objective of this research is to investigate the potential for replacing conventional fuels in various applications, focusing on the Alberta oil sands industry. Such investigations require systems-level approaches able to handle multiple criteria, uncertainty, and the views of multiple stakeholders. To address this need, the following are developed: life cycle assessment (LCA) and life cycle costing models of polygeneration systems; a life cycle-based framework for multi-sectoral resource use decisions; and a method combining LCA and real options analyses to yield environmental and financial insights into projects. These tools are applied to options for utilizing oil sands outputs, both the petroleum resource (bitumen) and by-products of its processing (e.g., asphaltenes, coke), within the oil sands industry and across other sectors. For oil sands on-site use, multiple fuels are assessed for the polygeneration of electricity, steam and hydrogen, in terms of life cycle environmental and financial impacts; asphaltenes gasification with carbon capture and storage (CCS) is the most promising option, able to reduce greenhouse gas (GHG) emissions to 25% of those of current natural gas-based systems. Coke management options are assessed with the life cycle-based framework; the most promising options are identified as: Electricity generation in China through integrated gasification combined cycle; and, hydrogen production in Alberta, either for sale or use by the oil sands industry. Without CCS, these options have amortized project values ranging from $21 to $160/t coke. The application of the combined LCA and real options analyses method finds that uncertainty in natural gas and potential carbon prices over time significantly impacts decisions on coke management; the formulated decision tree identifies increases of 29% and 11% in the financial and GHG emissions performance, respectively, of the overall coke management project compared to pursuing the decision identified by the life cycle-based framework. While promising options for replacing conventional fossil fuels are identified through systems-level analyses, there are trade-offs to be made among the financial, risk and environmental criteria.
|
443 |
Techno-economic and Environmental Assessments of Replacing Conventional Fossil Fuels: Oil Sands Industry Case StudiesMcKellar, Jennifer Marie 20 March 2014 (has links)
Conventional fossil fuels are widely used, however there are growing concerns about the security of their supply, volatility in their prices and the environmental impacts of their extraction and use. The objective of this research is to investigate the potential for replacing conventional fuels in various applications, focusing on the Alberta oil sands industry. Such investigations require systems-level approaches able to handle multiple criteria, uncertainty, and the views of multiple stakeholders. To address this need, the following are developed: life cycle assessment (LCA) and life cycle costing models of polygeneration systems; a life cycle-based framework for multi-sectoral resource use decisions; and a method combining LCA and real options analyses to yield environmental and financial insights into projects. These tools are applied to options for utilizing oil sands outputs, both the petroleum resource (bitumen) and by-products of its processing (e.g., asphaltenes, coke), within the oil sands industry and across other sectors. For oil sands on-site use, multiple fuels are assessed for the polygeneration of electricity, steam and hydrogen, in terms of life cycle environmental and financial impacts; asphaltenes gasification with carbon capture and storage (CCS) is the most promising option, able to reduce greenhouse gas (GHG) emissions to 25% of those of current natural gas-based systems. Coke management options are assessed with the life cycle-based framework; the most promising options are identified as: Electricity generation in China through integrated gasification combined cycle; and, hydrogen production in Alberta, either for sale or use by the oil sands industry. Without CCS, these options have amortized project values ranging from $21 to $160/t coke. The application of the combined LCA and real options analyses method finds that uncertainty in natural gas and potential carbon prices over time significantly impacts decisions on coke management; the formulated decision tree identifies increases of 29% and 11% in the financial and GHG emissions performance, respectively, of the overall coke management project compared to pursuing the decision identified by the life cycle-based framework. While promising options for replacing conventional fossil fuels are identified through systems-level analyses, there are trade-offs to be made among the financial, risk and environmental criteria.
|
444 |
Sustainability Assessment of Community Scale Integrated Energy Systems: Conceptual Framework and ApplicationsJanuary 2018 (has links)
abstract: One of the key infrastructures of any community or facility is the energy system which consists of utility power plants, distributed generation technologies, and building heating and cooling systems. In general, there are two dimensions to “sustainability” as it applies to an engineered system. It needs to be designed, operated, and managed such that its environmental impacts and costs are minimal (energy efficient design and operation), and also be designed and configured in a way that it is resilient in confronting disruptions posed by natural, manmade, or random events. In this regard, development of quantitative sustainability metrics in support of decision-making relevant to design, future growth planning, and day-to-day operation of such systems would be of great value. In this study, a pragmatic performance-based sustainability assessment framework and quantitative indices are developed towards this end whereby sustainability goals and concepts can be translated and integrated into engineering practices.
New quantitative sustainability indices are proposed to capture the energy system environmental impacts, economic performance, and resilience attributes, characterized by normalized environmental/health externalities, energy costs, and penalty costs respectively. A comprehensive Life Cycle Assessment is proposed which includes externalities due to emissions from different supply and demand-side energy systems specific to the regional power generation energy portfolio mix. An approach based on external costs, i.e. the monetized health and environmental impacts, was used to quantify adverse consequences associated with different energy system components.
Further, this thesis also proposes a new performance-based method for characterizing and assessing resilience of multi-functional demand-side engineered systems. Through modeling of system response to potential internal and external failures during different operational temporal periods reflective of diurnal variation in loads and services, the proposed methodology quantifies resilience of the system based on imposed penalty costs to the system stakeholders due to undelivered or interrupted services and/or non-optimal system performance.
A conceptual diagram called “Sustainability Compass” is also proposed which facilitates communicating the assessment results and allow better decision-analysis through illustration of different system attributes and trade-offs between different alternatives. The proposed methodologies have been illustrated using end-use monitored data for whole year operation of a university campus energy system. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2018
|
445 |
Security Testing for Web Applications in SDLC / Security Testing for Web Applications in SDLCSrilatha, Rondla, Someshwar, Gande January 2011 (has links)
Context: In Web applications, the Software vulnerability can be reduced by applying security testing in all phases of the software development life cycle (SDLC). Lot of vulnerabilities might occur if the security testing is applied in the last phase of SDLC. In order to mitigate these vulnerabilities, a lot of rework is required that involves reverse engineering in the development and design phases. To overcome this situation, organizations are shifting from security testing (performed in last phase) towards security testing in the early phases of SDLC. Objectives: The main objectives of this thesis are to gather the benefits and challenges of security testing in the last phase versus security testing in every phase of the SDLC. After gathering, authors want to compare both implementations because these days most organizations are shifting from last phase to every phase of SDLC. Justification to the reason can be achieved by this comparison. Methods: In order to satisfy the objectives of this thesis, a literature review and interviews were conducted. The literature review was conducted by gathering benefits and challenges of last phase and every phase of SDLC. Authors have applied coding technique to the data gathered from literature review. By using the results from literature review, a set of questions were framed. Based on these questions, interviews in various organizations were performed. To analyze the practitioner’s data we used Sorting and Coding technique. Then, we conducted a comparative analysis to compare both results. Results: Application of security testing in the last phase of the SDLC results in a lot of rework which in turn leads to instability in managing the cost, time and resources in an organisation. In order to overcome this, more and more organisations are introducing security testing at each and every phase of SDLC. Conclusions: It can be concluded that every phase of security testing in SDLC has more benefits than applying in last phase of SDLC. To evaluate this process more research is needed to acquire more knowledge of security testing in all phases of SDLC. Through literature review and interviews conducted, it is evident that security testing at early phases causes a reduction in rework which in turn leads to more efficient management of cost, time and resources of a project. / +91 8977404640
|
446 |
Evaluation of the sustainability of controlling diffuse water pollution in urban areas on a life cycle basisTomasini Montenegro, Claudia January 2013 (has links)
Diffuse water pollution in urban areas is growing due to polluted runoffs. Therefore, there is a need to treat this kind of pollution. Different structural treatment practices can be used for these purposes. However, little is known about their environmental, economic and social impacts. Therefore, the aim of this study has been to develop an integrated methodology for sustainability evaluation of structural treatment practices, considering environmental, economic and social aspects. Both environmental and economic evaluations have been carried out on a life cycle basis, using life cycle assessment and life cycle costing, respectively. For social evaluation, a number of social indicators, identified and developed in this research, have been used. The methodology has been applied to the case of the Magdalena river catchment in Mexico City. Three structural treatment practices have been analysed: bio-retention unit, infiltration trench and porous pavement. Based on the assumptions and the results from this work, the bio-retention unit appears to be environmentally the most sustainable option for treatment of diffuse water pollution. It is also the second-best option for social sustainability, slightly behind the porous pavement. However, if the costs of treatment are the priority, then the porous pavement would be the cheapest option. If all the sustainability aspects evaluated here are considered of equal importance, then the bio-retention unit is the most sustainable option. Therefore, trade-offs between the different sustainability aspects are important and should be considered carefully before any decisions are made on diffuse water pollution treatment. This also includes the trade-offs with the additional life cycle impacts generated by the treatment options compared to the impacts from the untreated runoff. The decisions can only be made by the appropriate stakeholders; however, some recommendations are given, based on the outcomes of this research.
|
447 |
Posuzování vlivu na životní prostředí při konstrukci výrobních strojů z pohledu emise vybraných skleníkových plynů / Assesment of the Environmental Impact in the Design of Production Machines in Terms of Greenhouse Gas Emissions of SelectedKrbalová, Maria January 2016 (has links)
The presented doctoral thesis is focused on environmental impact assessment of basic engineering materials used in a production machine construction. Ecological profile of the machine itself develops already in the phase of its design. It is not only about the choice of future machine parameters and materials that it is built from, but also about technologies used for its manufacture and operation conditions of the finished machine (consumption of energy and service fluids). The thesis occupies in detail with environmental impact analysis of the production machine design from the viewpoint of material production that mentioned machine consists of. The output from the performed analysis is methodology for evaluating of machine design from the viewpoint of greenhouse gas emissions. Created methodology enables evaluating of machine ecological profile and its possible adjustments even during pre-production stage. In the first part of the thesis the analysis of current legislation in the field of fighting against climate changes, reducing of products energy consumption and increasing of production machines energy efficiency is presented. Also in this part of the thesis description of methods that were used to achieve thesis goals is stated. Furthermore analysis of production machine as a system of structural components that fulfil the certain functions and description of used basic engineering materials are presented. The second part of the thesis is devoted to environmental impact analysis of the production machine design process. There the design process and environmental impact of machine design are described. This is followed by description of production machine life cycle and detailed analysis of undesirable substances emissions emitted during pre-production phases of machine life cycle (i.e. during the raw materials extraction and materials production). From this analysis the particular constituents’ pre-production phases which are sources of undesirable substances emissions (e.g. greenhouse gas emissions) were derived. The thesis also includes analysis of these constituents’ life cycles and description of electric power generation as a basic constituent of any phase of product life cycle. In this part of the thesis calculations of particular fuel type’s amounts that is required to produce 1 MWh of electric power and carbon dioxide amount produced during electric power generation are presented. The third part of the thesis contains created models of manufacturing processes of basic engineering materials and calculations of related emissions of selected greenhouse gases. The practical output from this part of the thesis is methodology that enables environmental impact assessment of machine design from the viewpoint of engineering materials used in its construction.
|
448 |
A Decision-making Framework for Hybrid Resource Recovery Oriented Wastewater SystemsRezaei, Nader 28 June 2019 (has links)
Water shortage, water contamination, and the emerging challenges in sustainable water resources management (e.g., the likely impacts of climate change and population growth) necessitate adopting a reverse logistics approach, which is the process of moving wastewater from its typical final destination back to the water supply chain for reuse purposes. This practice not only reduces the negative impacts of wastewater on the environment, but also provides an alternative to withdrawal from natural water resources, forming a closed-loop water supply chain. However, the design of such a supply chain requires an appropriate sustainability assessment, which simultaneously accounts for economic, environmental, and social dimensions. The overall aim of this work was therefore to contribute to the literature by evaluating the impacts of water reclamation and reuse according to the triple-bottom-line sustainability indicators (i.e., economic, environmental, and social) and to develop frameworks and mathematical models to help decision-makers, stakeholders, and officials with the design of sustainable water reclamation and reuse systems. The applicability of the developed frameworks and models was examined using real case studies and hypothetical scenario analyses. This enactment also revealed the tradeoffs and thresholds associated with the design of sustainable water reclamation and reuse systems.
To conquer the mentioned goal, the research was conducted in three major sections. The first part of the research was outlined to design possible scenarios for water reuse based on water reuse guidelines and evaluate the different types of end-use based on the three major dimensions of sustainability (i.e., economic, environmental and social aspects), simultaneously. The different reuse types considered include unrestricted urban reuse, agricultural reuse, indirect potable reuse (IPR), direct potable reuse (DPR), distributed unrestricted urban reuse, as well as some degree of decentralization of treatment plants for distributed unrestricted urban reuse. The tradeoff investigation and decision-making framework were demonstrated in a case study and a regret-based model was adopted as the support tool for multi-criteria decision-making. This study revealed that although increasing the degree of treatment for water reuse required implementation of advanced treatment options and it increased the implementation, operation, and maintenance (O&M) costs of the design, it increased the value of resource recovery significantly, such that it can offset the capital and O&M costs associated with the treatment and distribution for DPR. Improving the reclaimed water quality also reduced the environmental footprint (eutrophication) to almost 50% for DPR compared to the other reuse scenarios. This study revealed that the distance between the water reclamation facility and the end use plays a significant role in economic and environmental (carbon footprint) indicators.
In the second part of this research, a multi-objective optimization model was developed to minimize the costs and environmental footprint (greenhouse gas emissions), and maximize social benefits (value of resource recovery) of the water reclamation systems by locating the treatment facility, allocating treatment capacity, selecting treatment technology, and allocating customers (final reclaimed water users). The expansion of the water reclamation system in Hillsborough County, Florida was evaluated to illustrate the use of the model. The impacts of population density and topography (elevation variation) of the water service area on the model outputs were also investigated. Although the centralization of treatment facilities takes advantage of the economies of scale, the results revealed that simultaneous consideration of economic and environmental indicators favored decentralization of treatment facilities in the study area. This was mainly due to the significant decrease in water transfer requirements, especially in less populous areas. Moreover, the results revealed that contribution of population density to the optimal degree of decentralization of treatment facilities was significant.
In the last part of this work, hypothetical scenarios for a water service area were generated to evaluate the impacts of external variables on the design of water reclamation and reuse systems. Although the conducted sensitivity analyses in the previous sections revealed the tradeoffs and thresholds associated with the design of water reclamation systems, the concept of a hypothetical study helped with the elimination of case-specific factors and local conditions that could possibly influenced the outcomes. These factors, which were specific to the case studies (e.g., the location of candidate sites for implementation of water reclamation facilities and special population distribution patters) made barriers to the conclusions and hurdled the interpretation of findings. Two major factors, which were found to be significant among the factors influencing the design of water systems (i.e., elevation variation and population density), were selected for the evaluation. Accordingly, three different topographies (i.e., flat region, medium elevation variation, and hilly) and three types of population density (i.e., low, medium, and high) were considered for the design of hypothetical cases and the previous model developed in the second section was modified and used to evaluate the impacts. The results revealed that although decentralization of water reclamation facilities decreases the costs and environmental impacts associated with water transfer phase (i.e., wastewater collection and reclaimed water distribution), there were tradeoffs between the impacts of decentralization of treatment plants and the benefits from economies of scale for treatment. The results showed that when the population density is high and there is moderate to high elevation variations in the water service area, decentralization of treatment facilities is the beneficiary option. However, if the population density is low, economies of scale for treatment becomes more influential and lower degrees of decentralization of treatment facilities is preferred.
|
449 |
Preliminary design and multi-criteria analysis of solutions for widening an existing concrete bridge : Case of the Bridge of Chaillot in Vierzon (France)Fline, Pierre January 2011 (has links)
Europe experienced the destruction of numerous infrastructures during World War II, followed by a reflation and a strong economic growth during the next two decades allowing a more perennial and durable situation. A classical bridge lasting in general around 80 years, one should observe that these constructions built after the war will have to be either replaced either seriously strengthened in a few years. Besides, since the needs also vary over time, transportation infrastructures built during those years might not be adapted to the actual needs anymore – some bridges might thus have to be widened. A case study has been chosen in order to simulate under which conditions the widening of such a bridge can be performed. This road bridge, located in Vierzon in France, is rather simple since it is made of simply supported prestressed concrete beams and of reinforced concrete piers. It has been chosen in particular for its reduced size – three spans of 30 m each and two road lanes – that corresponded well to this project. Based on some data provided when the bridge was initially built and on a visual inspection, this project suggests six technical solutions to double the actual amount of lanes. An evaluation of the performance of the solutions according to three criteria – durations of works, cost of the works, and environmental impact – is made in order to give recommendations regarding the optimal solution. The results show that in spite of being installed quickly, adding steel beams is more expensive and has a greater impact on the environment than adding prestressed concrete beams. Regarding the modification of piers, the solution suggesting widening the existing piers is preferable than adding new extra piers according to all the criteria. Consequently, among all the solutions analysed, the optimal one is also the simplest one. Finally, the limits of the study and some suggestions for improvements are indicated.
|
450 |
Náklady životního cyklu budovy / Building Life Cycle CostsBohadlová, Darina January 2012 (has links)
This diploma thesis deals with the life-cycle cost of the building for teaching and research. The theoretical part deals with the introduction of life-cycle cost method. A description ofdetermining life-cycle cost and procedure of processing. In the practical part of the budgetis prepared surveyed the building, which is divided into functional parts and the fixed costs of repair and reconstruction over the lifetime of the building. At the end of life are roughlydetermined the cost of demolition and waste removal. This whole process is summarized in the table, which sets the cost of operating the building throughout its life.
|
Page generated in 0.0354 seconds