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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.
381

The Life-Cycle Assessment of a Single-Storey Retail Building in Canada

Van Ooteghem, Kevin January 2010 (has links)
In North America, the operation of buildings accounts for approximately one third of the total energy use and greenhouse gas emissions annually. Office buildings are responsible for roughly 35% of the total commercial/institutional secondary energy use in Canada, followed by retail buildings at 17% (NRCan, OEE, 2010). In recent years, a number of researchers from around the world have conducted life-cycle assessment (LCA) studies to investigate the impacts of buildings on the environment. Most studies have focused on three types of buildings: office buildings, single residential dwellings, and multi-unit residential apartments. There have been almost no comprehensive LCA studies of retail buildings, specifically single-storey retail buildings. This is a problem, since compared to office buildings, single residential dwellings, and multi-unit residential apartments, retail buildings consume approximately 1.2, 2.0, and 2.3 times more energy per floor area respectively (NRCan, OEE, 2010). In addition, retail buildings usually undergo major resource intensive renovations far sooner than other building types. Therefore, the primary goal of this study was to conduct a comprehensive LCA for the components of a single-storey retail building located in Toronto, Canada, to determine which building components contribute the most towards the total life-cycle energy use and global warming potential (GWP) after 50 years. Using the latest LCA techniques, the total life-cycle energy use and GWP was calculated for 220 different building components including: exterior infill walls, roofs, structural systems, floors, windows, doors, foundations, and interior partition walls. Also, a comprehensive LCA study was conducted for five single-storey retail buildings (including a pre-engineered steel building system which is lacking in the literature), in order to determine which components of a single-storey retail building are responsible for the most environmental damage. For a typical single-storey retail building located in Toronto, Canada, the operating energy (and GWP) accounts for about 91% (88%) and the total embodied energy (and GWP) accounts for about 9% (12%) of the total energy (and GWP) after 50 years. The roof alone is responsible for nearly half of the total embodied energy and GWP of the entire building. The LCA study also found that after 50 years, the total energy (and GWP) of the five case study buildings only differed at most by 6% (7%), regardless of the choice of structural system, or whether the building was made predominately of steel or wood building components. This thesis concludes with a prioritized list of recommendations for reducing the total life-cycle energy use and GWP of a single-storey retail building in Canada.
382

CARBON LIFE-CYCLE AND ECONOMIC ANALYSIS OF FOREST CARBON SEQUESTRATION AND WOODY BIOENERGY PRODUCTION

Shrestha, Prativa 01 January 2013 (has links)
Sequestering carbon in standing biomass, using woody bioenergy, and using woody products are the three potential ways to utilize forests in reducing greenhouse gases (GHGs) and mitigating climate change. These forestry related strategies are, however, greatly influenced by the existing markets and market based policies. This study focuses on the first two forest strategies. It investigates the combined impact of carbon and woody bioenergy markets on two different types of forests in the US – oak dominated mixed hardwood forests in the Central Hardwood Forests Region and loblolly pine forests in the southeastern US. A modification of the Harman model was used for the economic analysis of carbon sequestration and harvesting woody biomass for bioenergy. A forest carbon life-cycle assessment was used to determine the carbon emissions associated with management of forests and harvesting of wood products. Results from this study indicate that carbon payments and woody bioenergy production increase the land expectation value (LEV) for both forest types.
383

Improving microalgae biofuel production: an engineering management approach

Mathew, Domoyi Castro 07 1900 (has links)
The use of microalgae culture to convert CO2 from power plant flue gases into biomass that are readily converted into biofuels offers a new frame of opportunities to enhance, compliment or replace fossil-fuel-use. Apart from being renewable, microalgae also have the capacity to utilise materials from a variety of wastewater and the ability to yield both liquid and gaseous biofuels. However, the processes of cultivation, incorporation of a production system for power plant waste flue gas use, algae harvesting, and oil extraction from the biomass have many challenges. Using SimaPro software, Life cycle Assessment (LCA) of the challenges limiting the microalgae (Chlorella vulgaris) biofuel production process was performed to study algae-based pathway for producing biofuels. Attention was paid to material use, energy consumed and the environmental burdens associated with the production processes. The goal was to determine the weak spots within the production system and identify changes in particular data-set that can lead to and lower material use, energy consumption and lower environmental impacts than the baseline microalgae biofuel production system. The analysis considered a hypothetical transesterification and Anaerobic Digestion (AD) transformation of algae-to- biofuel process. Life cycle Inventory (LCI) characterisation results of the baseline biodiesel (BD) transesterification scenario indicates that heating to get the biomass to 90% DWB accounts for 64% of the total input energy, while electrical energy and fertilizer obligations represents 19% and 16% respectively. Also, Life Cycle Impact Assessment (LCIA) results of the baseline BD production scenario show high proportional contribution of electricity and heat energy obligations for most impact categories considered relative to other resources. This is attributed to the concentration/drying requirement of algae biomass in order to ease downstream processes of lipid extraction and subsequent transesterification of extracted lipids into BD. Thus, four prospective alternative production scenarios were successfully characterised to evaluate the extent of their impact scenarios on the production system with regards to lowering material use, lower energy consumption and lower environmental burdens than the standard algae biofuel production system. A 55.3% reduction in mineral use obligation was evaluated as the most significant impact reduction due to the integration of 100% recycling of production harvest water for the AD production system. Recycling also saw water demand reduced from 3726 kg (freshwater).kgBD- 1 to 591kg (freshwater).kgBD- 1 after accounting for evaporative losses/biomass drying for the BD transesterification production process. Also, the use of wastewater/sea water as alternative growth media for the BD production system, indicated potential savings of: 4.2 MJ (11.8%) in electricity/heat obligation, 10.7% reductions for climate change impact, and 87% offset in mineral use requirement relative to the baseline production system. Likewise, LCIA characterisation comparison results comparing the baseline production scenarios with that of a set-up with co-product economic allocation consideration show very interesting outcomes. Indicating -12 MJ surplus (-33%) reductions for fossil fuels resource use impact category, 52.7% impact reductions for mineral use impact and 56.6% reductions for land use impact categories relative to the baseline BD production process model. These results show the importance of allocation consideration to LCA as a decision support tool. Overall, process improvements that are needed to optimise economic viability also improve the life cycle environmental impacts or sustainability of the production systems. Results obtained have been observed to agree reasonably with Monte Carlo sensitivity analysis, with the production scenario proposing the exploitation of wastewater/sea water to culture algae biomass offering the best result outcome. This study may have implications for additional resources such as production facility and its construction process, feedstock processing logistics and transport infrastructure which are excluded. Future LCA study will require extensive consideration of these additional resources such as: facility size and its construction, better engineering data for water transfer, combined heat and power plant efficiency estimates and the fate of long-term emissions such as organic nitrogen in the AD digestate. Conclusions were drawn and suggestions proffered for further study.
384

Diesel from wood biomass : Screening LCA of a proposed KDV-plant in Jämtland, Sweden

Chandolias, Pavlos January 2014 (has links)
The KDV-process uses catalytic depolymerisation to convert biomass into diesel oil. The environmental performance of KDV-diesel in a proposed KDV-plant located in the County of Jämtland, Sweden, was assessed using Life Cycle Assessment (LCA) methodology. The functional unit of the study was one litre of KDV-diesel and the environmental impact categories that were considered were Global Warming Potential (GWP), Eutrophication Potential (EP) and Acidification Potential (AP). The acquisition of wood biomass significantly affected the life cycle performance of KDV-diesel production in all three impact categories. When benchmarked against conventional diesel oil, KDV-diesel contributed significantly less to GWP, since there are no fossil carbon dioxide (CO2) emissions from the use phase, but it contributed more to EP and AP due to slightly higher emissions in the production phases. This conclusion holds true for five investigated electricity-supply scenarios for the production of KDV-diesel. Each scenario utilised a different source for electricity production: wind power; hydro power; nuclear power; coal power; and using part of the produced KDV-diesel for on-site electricity production. Another scenario analysis compared an alternative use of the wood biomass and assumed that the same amount of wood biomass was used to generate bio-electricity, instead of being converted into KDV-diesel. The scenario analysis indicated that whether wood biomass should be used for KDV-diesel production or for bio-electricity production depends on the type of electricity that is used throughout the life cycle of KDV-diesel. / KDV-processen använder katalytisk depolymerisering för att omvandla biomassa till dieselolja. Miljöprestanda för KDV-diesel från en föreslagen KDV-anläggning i Jämtland län, Sverige, har studerats med livscykelanalys (LCA) metodik. Studiens funktionella enhet var en liter av KDV-diesel och de studerade miljöpåverkanskategorierna var Klimatpåverkan (GWP), Övergödning (EP) och Försurning (AP). Skogsbruket påverkade signifikant livscykelprestanda för KDV-dieselproduktion från trädbiomassa i de tre studerade miljöpåverkanskategorierna. Kontrasterad mot konventionell dieselolja bidrog KDV-diesel betydligt mindre till GWP eftersom det inte finns några utsläpp av fossil koldioxid (CO2) under användningsfasen, men bidrog samtidigt mer till EP och AP på grund av något högre utsläpp i produktionsfasen. Denna slutsats gäller för fem olika elförsörjning scenarier för produktion av KDV-diesel som studerats. Varje scenario använde olika typ av elproduktion: vindkraft; vattenkraft; kärnkraft; kolkraft; samt att använda en del av den producerade KDV-diesel för egen elproduktion. En annan scenarioanalys studerade alternativ användning av trädbiomassan och antog att samma mängd träbiomassa användes för att generera bio-elektricitet istället för KDV-diesel. Scenarioanalysen visade att utfallet för ifall träbiomassan borde användas för produktion av KDV-diesel eller bio-electricitet beror på typen av elproduktion som används för KDV-diesels livscykel. / Η διαδικασία KDV χρησιμοποιεί καταλυτικό αποπολυμερισμό για τη μετατροπή βιομάζας σε καύσιμο ντίζελ. Οι περιβαλλοντικές επιδόσεις του KDV-ντίζελ σε μια προτεινόμενη μονάδα KDV που βρίσκεται στην περιφέρεια Γιέμτλαντ της Σουηδίας, αξιολογήθηκαν με τη μέθοδο Αξιολόγησης του Κύκλου Ζωής (LCA). Η λειτουργική μονάδα της μελέτης ήταν ένα λίτρο KDV-ντίζελ και οι κατηγορίες περιβαλλοντικών επιπτώσεων που εξετάστηκαν ήταν το Δυναμικό Θέρμανσης του Πλανήτη (GWP), το Δυναμικό Ευτροφισμού (EP) και το Δυναμικό Οξίνισης (AP). Η απόκτηση της βιομάζας ξύλου επηρέασε σημαντικά την απόδοση του κύκλου ζωής της παραγωγής KDV-ντίζελ και στις τρεις κατηγορίες περιβαλλοντικών επιπτώσεων. Σε σύγκριση με το συμβατικό πετρέλαιο ντίζελ, το KDV-ντίζελ συνέβαλε σημαντικά λιγότερο στο GWP, δεδομένου ότι δεν υπάρχουν εκπομπές διοξειδίου του άνθρακα (CO2) ορυκτής προέλευσης κατά τη φάση της χρήσης, αλλά συνέβαλε περισσότερο στο EP και στο AP λόγω ελαφρώς υψηλότερων εκπομπών στις φάσεις της παραγωγής. Το συμπέρασμα αυτό ισχύει για πέντε σενάρια παροχής ηλεκτρισμού για την παραγωγή του KDV-ντίζελ που μελετήθηκαν. Σε κάθε σενάριο χρησιμοποιήθηκε μια διαφορετική πηγή ενέργειας για την παραγωγή ηλεκτρισμού: αιολική ενέργεια, υδροηλεκτρική ενέργεια, πυρηνική ενέργεια, ηλεκτροπαραγωγή με καύση άνθρακα και χρήση μέρους του παραγόμενου KDV-ντίζελ για επιτόπια παραγωγή ηλεκτρισμού. Μια διαφορετική ανάλυση σεναρίου συνέκρινε μια εναλλακτική χρήση της βιομάζας ξύλου, υποθέτοντας ότι η ίδια ποσότητα βιομάζας ξύλου χρησιμοποιήθηκε για την παραγωγή βιο-ηλεκτρισμού, αντί να μετατραπεί σε KDV-ντίζελ. Η ανάλυση σεναρίου κατέδειξε ότι η χρήση της βιομάζας ξύλου για την παραγωγή KDV-ντίζελ ή για την παραγωγή βιο-ηλεκτρισμού εξαρτάται από την πηγή ενέργειας που χρησιμοποιείται για την παραγωγή ηλεκτρισμού καθ’όλη τη διάρκεια του κύκλου ζωής του KDV-ντίζελ.
385

Life Cycle Assessment of Asphalt Roads : Decision Support at the Project Level

Butt, Ali Azhar January 2014 (has links)
Transport infrastructures such as roads are assets for the society as they not only ensure mobility but also strengthen society’s economy. Considerable amount of energy and materials, that include bitumen, aggregates and asphalt, are required to build and maintain roads. Improper utilization of energy and/or use of materials may lead to more waste and higher costs. The impact on the environment cannot be neglected either. Life cycle assessment (LCA) as a method can be used to assess the environmental impacts of a road system over its entire life time. Studying the life cycle perspective of roads can help us improve the technology in order to achieve a system that has a lower impact on the environment. There are number of LCA tools available. However, implementation of such tools is still unseen in real road projects. This clearly indicates that there are gaps which are needed to be filled in order to bring these tools into practice. An open road LCA framework was developed for the asphalt roads in order to help in decision support at the late project planning stage such as that related to the green procurement. The framework takes into account the construction, maintenance and end of life phases and focuses on energy and greenhouse gas (GHG) emissions. Threshold values for the production of some additives were also determined to show how LCA tools can help material suppliers to improve the road materials production processes and the road authorities to set limits on the use of different materials based on the environmental criteria. Additive consideration and feedstock energy in road LCAs were also identified as gaps that were looked in detail. The attributes that are important to consider in an asphalt road LCA that seeks to serve as a decision support in a procurement situation are described. A brief literature review was carried out that focused on project LCAs, and specifically those considering pavements, as this level is assumed to be appropriate for questions relevant in a procurement situation. Following the different standards; road LCAs developed all over the world have generated a lot of knowledge and the studies have been different from each other such as in terms of goals and system boundaries. Hence, the patterns observed have been very different from study to study. It was also difficult to assess the decision support level for which the various LCA frameworks or tools were developed. It is important to define system boundaries based on where in the system the decision support is needed. For LCA to be useful for decision support in a procurement situation, it is important to have a clear understanding of the attributes that constitute the life cycle phases and how data of high quality for them are obtained. The level of consistency and transparency of road LCAs becomes increasingly important in pre-procurement and procurement situations. The key attributes used in a road LCA should mirror the material properties used in a pavement design and therefore be closely linked to the performance of the road in its life cycle. From the different case studies, it was found that asphalt production and transportation of materials are usually highest in the energy and GHG emissions chain. It is highly favorable to have the quarry site, the asphalt plant and the construction site not far from each other and to use the electricity that has been produced in an efficient way. Based on the laboratory test results, it is shown that the effects of chemical warm mix asphalt additives (WMAA)s must be evaluated on a case by case basis since WMAA interaction with the aggregate surface mineralogy appears to play a significant role and thus affects its long term structural behavior. Using the material properties obtained from the Superpave indirect tensile test (IDT) results, pavement thickness design was done in which Arlanda aggregate based asphalt mixtures resulted in thinner pavements as compared to Skärlunda aggregate based asphalt mixtures for the same design life period. Energy (feedstock and expended) saving and reduction in GHG emissions were also seen with addition of WMAA, for both aggregate type cases, based on the data used. Importantly, the results presented illustrate the importance of a systems based LCA approach for evaluating the sustainability for different design and construction options. In this context, having actual pavement material properties as the key attributes in the LCA enables a pavement focused assessment of environmental costs associated with different design options. / <p>QC 20141118</p>
386

Evaluation of an alternative organic waste disposal system in Chevron-Escravos : a case study / O.I. Bojor

Bojor, Olire Innocent January 2008 (has links)
The research presented in this dissertation focuses on the waste management techniques currently used by Chevron-Escravos Nigeria Limited (CENL), as background knowledge of the existing waste disposal system practiced by the company. Investigation has shown that more than four tons (4tons) of organic food waste that CENL generates daily is being disposed of by using incineration and landfilling of the resulting residues. The high recoverability and economic values in form of nutrients and stored energy is not being considered. The main dissertation problem was to develop an alternative means of promoting the economic and environmental recoverability of these huge amounts of organic wastes, by developing a disposal technique other than the current incineration and landfill methods. The mechanism considered to achieve this objective was laid out in the customized organic waste converter or processor that provides one of the baselines for this dissertation. It also presents a procedural description of converting organic food waste to bio-feeds and feedstock of high quality. This alternative processing and utilization of organic food waste was carried out to provide information about tradeoffs to the current practice of incineration and landfill management systems. This was done to guide decision making and to serve as a framework within which the plausibility of the proposed solution could be examined. A comparative analysis of the two scenarios of waste to feed and waste to incineration system, the environmental impact, economic viability, and opportunity cost of recycling organic food waste produce of animal bio-feed was assessed by using: • Life cycle analysis (LCA) • By-products Breakeven Sale Product (BBSP) model. The BBSP model evaluates the opportunity of recycling the organic food waste in production of animal bio-feed to waste incineration. The outcome of the dissertation indicates that incineration is an important contributor to human and environmental toxicity and global warming. The proposed solution (recycling approach) balances the socio-economic, political and environmental safety by producing renewable, clean and eco-friendly feed and by-products. It was also concluded that there are alternative possibilities for the utilization of industrial organic food waste, where both the energy and nutrients are completely utilized, rather than the norms of conversion through chemical, biological, and thermal or other forms of energy fuels), which typically utilizes only one of these (calorific contents) categories at a time. The above mentioned utilization can be achieved by transforming the current waste disposal system. By introducing an alternative model for the recycling of plant and animal nutrients and the utilization of energy, renewable energy can be saved, human health and the environment can be protect and a sustainable economy can be maintained. In summary, it was demonstrated that there is huge capital losses and environmental contamination due to the current waste management practices. Recycling of OF W for feed production would be cost effective method that contributes towards protecting the environment achieving economic sustainability. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2009.
387

Phase Change Materials for Solar Thermal Energy Storage

Allred, Paul 21 March 2014 (has links)
Phase change materials (PCMs) are a viable option for compact thermal energy storage. Effective designs using PCMs require accurate knowledge of the thermal and physical properties, but for many PCMs these are not well known, and when known the knowledge is sometimes contradictory. Therefore, physical characteristics of several promising PCMs (K3PO4·7H2O, FeCl3·6H2O, Mn(NO3)2·4H2O) were determined. In addition, a life cycle assessment (LCA) of dodecanoic acid in a solar thermal energy storage system was carried out to determine the environmental impact for energy storage. This LCA showed that dodecanoic acid in a solar energy system would save energy and facilitate CO2 reductions. However, the economic cost is high and is unlikely to be implemented without incentives. Finally an experimental testbed for a solar thermal system utilizing dodecanoic acid was built. Preliminary measurements demonstrated the utility of this system.
388

Evaluation of an alternative organic waste disposal system in Chevron-Escravos : a case study / O.I. Bojor

Bojor, Olire Innocent January 2008 (has links)
The research presented in this dissertation focuses on the waste management techniques currently used by Chevron-Escravos Nigeria Limited (CENL), as background knowledge of the existing waste disposal system practiced by the company. Investigation has shown that more than four tons (4tons) of organic food waste that CENL generates daily is being disposed of by using incineration and landfilling of the resulting residues. The high recoverability and economic values in form of nutrients and stored energy is not being considered. The main dissertation problem was to develop an alternative means of promoting the economic and environmental recoverability of these huge amounts of organic wastes, by developing a disposal technique other than the current incineration and landfill methods. The mechanism considered to achieve this objective was laid out in the customized organic waste converter or processor that provides one of the baselines for this dissertation. It also presents a procedural description of converting organic food waste to bio-feeds and feedstock of high quality. This alternative processing and utilization of organic food waste was carried out to provide information about tradeoffs to the current practice of incineration and landfill management systems. This was done to guide decision making and to serve as a framework within which the plausibility of the proposed solution could be examined. A comparative analysis of the two scenarios of waste to feed and waste to incineration system, the environmental impact, economic viability, and opportunity cost of recycling organic food waste produce of animal bio-feed was assessed by using: • Life cycle analysis (LCA) • By-products Breakeven Sale Product (BBSP) model. The BBSP model evaluates the opportunity of recycling the organic food waste in production of animal bio-feed to waste incineration. The outcome of the dissertation indicates that incineration is an important contributor to human and environmental toxicity and global warming. The proposed solution (recycling approach) balances the socio-economic, political and environmental safety by producing renewable, clean and eco-friendly feed and by-products. It was also concluded that there are alternative possibilities for the utilization of industrial organic food waste, where both the energy and nutrients are completely utilized, rather than the norms of conversion through chemical, biological, and thermal or other forms of energy fuels), which typically utilizes only one of these (calorific contents) categories at a time. The above mentioned utilization can be achieved by transforming the current waste disposal system. By introducing an alternative model for the recycling of plant and animal nutrients and the utilization of energy, renewable energy can be saved, human health and the environment can be protect and a sustainable economy can be maintained. In summary, it was demonstrated that there is huge capital losses and environmental contamination due to the current waste management practices. Recycling of OF W for feed production would be cost effective method that contributes towards protecting the environment achieving economic sustainability. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2009.
389

Incorporating life cycle assessment into the LEED Green Building rating system

Optis, Michael 12 August 2008 (has links)
Reused, recycled and regional product criteria within the LEED Green Building rating system are not based on comprehensive environmental assessments and do not ensure a measurable and consistent reduction of environmental burdens. A life cycle assessment (LCA) was conducted for the LEED-certified Medical Sciences Building at the University of Victoria to illustrate how LCA can be used to improve these criteria. It was found that a lack of public LCA data for building products, insufficient reporting transparency and inconsistent data collection methodologies prevent a full incorporation of LCA into LEED. At present, LCA data can be used to determine what building products are generally associated with the highest environmental burdens per unit cost and thus require separate LEED criteria. Provided its deficiencies are rectified in the future, LCA can be fully incorporated into LEED to design environmental burden-based criteria that ensure a measurable and consistent reduction of environmental burdens.
390

Environmental analysis of biologically inspired self-cleaning surfaces

Raibeck, Laura 10 July 2008 (has links)
Biologically inspired design is used as an approach for sustainable engineering. Taking a biologically inspired approach, one abstracts ideas and principles from nature, an inherently sustainable system, and uses them in engineering applications with the goal of producing environmentally superior designs. One such biological idea with potential environmental benefits for engineering is microscale and nanoscale surface roughness found on the Lotus plant and many other surfaces in nature. These surfaces repel water and aid in contaminant removal; this self-cleaning phenomenon is called the "Lotus Effect," in honor of the plant first observed to exhibit it. The structures responsible for the Lotus Effect inspired research and development of many technologies capable of creating hydrophobic, self-cleaning surfaces, and many potential self-cleaning surface applications exist beyond nature's intended application of cleaning. While statements have been made about the environmental benefits of using a self-cleaning surface, only limited scientific data exist. Artificial self-cleaning surfaces are successfully cleaned using fog or mist. This shows that such surfaces can be cleaned with less energy and water intensive methods than the more conventional methods used to clean regular surfaces, such as spray or solvent cleaning. This research investigates the potential environmental burden reductions associated with using these surfaces on products. A life cycle assessment is performed to determine the environmental burdens associated with manufacturing a self-cleaning surface, for three production methods: a chemical coating, a laser ablated steel template, and an anodized aluminum template. The environmental benefits and burdens are quantified and compared to those of more conventional cleaning methods. The results indicate that self-cleaning surfaces are not necessarily the environmentally superior choice.

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