• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 84
  • 34
  • 22
  • 10
  • 7
  • 4
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 188
  • 73
  • 66
  • 52
  • 46
  • 45
  • 29
  • 26
  • 20
  • 19
  • 17
  • 16
  • 15
  • 15
  • 15
  • 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.
91

Sustainability assessment of nuclear power in the UK using an integrated multi-criteria decision-support framework

Youds, Lorraine Helen January 2013 (has links)
In the UK, the debate surrounding energy production lies at the forefront of the political agenda, with growing emphasis on achieving an increasingly sustainable energy mix into the future. The nuclear option is especially debatable - issues such as waste management and decommissioning receive much attention. In addition, the many stakeholders interested in nuclear power display very divergent views on its sustainability. Since the turn of the century, nuclear power has received much attention globally, with many nations’ governments taking consideration of the potential benefits of new nuclear adoption. Conversely, the Fukushima nuclear disaster has led to new nuclear resistance in other nations, such as Germany, where plans have been made to stop nuclear power generation completely. This research aims to help inform the debate on nuclear power and the future UK electricity mix. A multi-criteria decision support framework (developed by the SPRIng Project) has been used for these purposes, taking into account technical, economic, environmental and social criteria.The methodology used in this work has involved: stakeholder consultation; use of future electricity scenarios; sustainability assessment of current and future electricity options (Pressurised Water Reactor, European Pressurised Reactor, European Fast Rector, coal, gas, solar and wind power, and coal carbon capture and storage [CCS] power); assessment of future electricity scenarios based on both sustainability impacts and stakeholder (expert and public) preferences for the sustainability indicators and electricity technologies. The sustainability assessment of future nuclear power options and coal CCS power have been carried out here for the first time in a UK-specific context.Based on the public and expert opinions on the importance of different sustainability indicators, results of the scenario analysis suggest that the scenario with a high penetration of low-carbon technologies (nuclear [60%] and offshore wind power [40%]) is the most sustainable. For the sample considered in this study, this finding is not sensitive to different stakeholder and public opinions on the importance of the sustainability indicators. However, when the stakeholder preferences for individual technologies are considered, scenarios with high penetration of renewables (26-40% solar and 20-48% wind) become the preferred options. This is due to the favourable stakeholder opinion on solar and wind power. In that case, the scenario with high penetration of nuclear is never the preferred option due to the low to moderate stakeholder preference for nuclear power.Therefore, the results from this research suggest that the ‘sustainability’ of different electricity options and scenarios is highly dependent on stakeholder preferences and priorities. Thus, for successful future deployment of these options and implementation of energy policy measures, transparency of information on the impacts of electricity options is key in ensuring that stakeholder opinions are founded in the actual rather than the perceived impacts of these options.
92

Emission reduction in waste incineration : A comparison of three applicable measures

Linde, Adam January 2021 (has links)
Utilization of waste as fuel for heat and power production is commonplace in Sweden, and the fossil emissions from the incineration of waste is primarily derived from the share of plastics in the fuel. Reducing the share of fossil material in the fuel should therefore lead to diminished local emissions. Alternatively, district heating with waste incineration have potential for implementation of CCS technology, that have the possibility to create negative emissions. The purpose of this study is to evaluate the potential of emission reduction and cost efficiency for three different measures that can be applied for waste incineration: sorting of waste, requirement specification and implementation of CCS technology. This was made with the case of Stockholm Exergi, a district heating actor in the Stockholm region with a desire to achieve emission reduction sufficient to offset additional emissions from a new waste incineration facility in development. The measures were compared by constructing distinct scenarios where the emissions and costs of the scenarios could be found in comparison to a reference case where no measures had been applied. For this, modelling of the properties of the waste streams used as fuel was necessary. The results showed that the capacity for sorting is not sufficient to achieve the desired levels of emission reduction on its own, while it is a cost-efficient measure. Requirement specification together with sorting can reduce the emissions to desired levels, but the required reduction of plastics in the fuel is significant. The additional quantities of waste required to produce energy at the same level as before limiting the shares of plastic results in an income from gate fees that mitigate the potential decrease in value of the gate fees brought on by requirement specification. Implementation of CCS technology would create significant negative emissions and yield overall net negative emissions for the studied facilities, but the cost of the technology would create a dependency of external incentives to keep it profitable.
93

Posouzení metod CCS a CCU / Assessment of CCS and CCU methods

Kroupa, Zdeněk January 2020 (has links)
The thesis focuses on CCS and CCU technologies, which could find application in industry and other sectors in the future. These technologies are used to reduce CO2 emissions, mainly from point sources. This thesis provides a comprehensive overview and division of CCS and CCU technologies and points out negative effects of its installation. Part of the work is also a comparison of individual steps of technology, both from an energetic and financial point of view. The aim is to show a wide range of influences on the final price and a significant discrepancy in the results of some scientific works. At the same time, in some parts, you can find a detailed description of individual parts of the technology.
94

Estudo da infecção intramamária e dos métodos de triagem para detecção de mastite subclínica em búfalas /

Sales, Danielle Cavalcanti January 2019 (has links)
Orientador: Humberto Tonhati / Resumo: A mastite é a enfermidade que mais causa prejuízos de ordem quantitativa e qualitativa nos sistemas de produção de leite no mundo. A prevenção e controle da doença precisam envolver atividades práticas e eficientes que auxiliem a tomada de decisões rápidas na fazenda. Os métodos de triagem para o diagnóstico da mastite aplicados às búfalas leiteiras são aqueles desenvolvidos especificamente para as vacas. Assim, o objetivo geral da tese foi estudar a mastite subclínica em búfalas e avaliar os métodos de triagem que auxiliam o diagnóstico da doença na fazenda. O trabalho se divide em quatro capítulos que tratam de: revisar a literatura sobre as temáticas (I); caracterizar o leite de quartos mamários com e sem infecção intramamária, e avaliar a associação entre a presença de infecção intramamária e as características microbiológicas do leite de quartos mamários de búfalas, posição dos tetos e os resultados dos métodos de triagem (II); e avaliar os testes rápidos California Mastitis Test , Somaticell e condutividade elétrica como métodos de triagem para auxiliar o diagnóstico da mastite subclínica em búfalas diretamente na fazenda (III). O estudo foi realizado em um rebanho de búfalas no estado do Rio Grande do Norte. Foram colhidas 533 amostras de leite de quartos mamários que foram submetidas à contagem eletrônica de células somáticas (CCS), aos testes de triagem (California Mastitis Test – CMT, teste Somaticell - SO e condutividade elétrica – CEL) e ao exame microbiológico pa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Mastitis is the disease that causes the most quantitative and qualitative losses in milk production systems in the world. Disease prevention and control need to involve practical and efficient actions that may help on decision-making on farm. Screening methods applied for mastitis diagnosis in dairy buffaloes are those developed specifically for cows. Thus, the objective of the thesis was to study subclinical mastitis in buffaloes and to evaluate the screening methods that help the disease diagnosis in farm. The work is divided into four chapters that deal with: reviewing the literature on the themes (I); to characterize breast milk with and without intramammary infection and to evaluate the association between the presence of intramammary infection and microbiological characteristics of buffalo milk, teat position, and the results of screening methods (II); and evaluate the California Mastitis Test (CMT), Somaticell (SO) and electrical conductivity (EC) rapid tests as a screening method to assist the diagnosis of subclinical mastitis in buffaloes on farm (III). The work was developed in a buffaloes commercial herd in the Rio Grande do Norte state. A total of 533 randomly selected milk samples were obtained and submitted to electronic somatic cell count (SCC), screening tests (CMT, SO and EC) and microbiological examination for diagnosis of subclinical mastitis (IMM: positive/negative), infection classification (negative, contagious, environmental, mixed and opportunistic) an... (Complete abstract click electronic access below) / Doutor
95

Intégration du critère de dioxyde de carbone dans la localisation des industries : le cas du cluster industriel du Havre / Integration of carbon dioxide factor in industrial location : the case of Le Havre industrial cluster

Musset, Yann 02 October 2014 (has links)
Les problèmes environnementaux, notamment ceux qui, liés au réchauffement global, ont attiré de plus en plus l’attention des décideurs de l'entreprise. Leurs préoccupations sur ces problèmes les conduisent à une réflexion de réorganisation de leurs activités. Pour les entreprises industrielles qui doivent faire face au problème des émissions de CO2, le soutien de gouvernement local qui concerne la gestion des émissions de CO2 devient non négligeable. Dans cette thèse, nous interviewons 50 décideurs de l'industrie, le gouvernement et la communauté universitaire. L’importance du problème des émissions de CO2 dans le choix de site est globalement évaluée. Nos observations suggèrent que le problème du CO2 est un facteur mineur dans la localisation des sites. Il peut être intégré dans le coût global. Pour les autorités locales, il n'est pas nécessaire d'investir dans les infrastructures de traitement des émissions de CO2 à l'heure actuelle. Nos résultats fournissent ainsi une meilleure compréhension du problème des émissions de CO2 pour les décideurs des industries locales. / Environmental problems, especially those related to the global warming have attracted extensive attention from the decision makers of companies. Their concerns on the environmental problems lead them to a reform of the mode of management. For the decision makers from industry who have to face the CO2 problem, whether they can be supported by the local government with respect to managing CO2 emissions becomes non trivial. In this thesis, we interviewed 50 decision makers from industries, government, and academic community. The significance of the CO2 problem in site selection is comprehensively evaluated. Our observations suggest that the CO2 problem is a minor factor. It can be measured by the cost. For the local government, there is no need to invest in the infrastructures of CO2 treatment at present. Our results thus provide a better understanding of the CO2 problem for the decision makers of local industries.
96

Carbon capture from reheating furnaces in the Swedish steel industry : evaluation of techno-economic feasibility

Haglund, Anna January 2020 (has links)
The reduction of greenhouse gas emissions is important to keep climate change under control. One of the largest CO2 emitters of the Swedish industries is the steel industry. This is, among others, due to the need of heat treatments and reheating processes depending on high temperatures and fossil fuels. The business organisation Jernkontoret and their department for energy and furnace technique is working towards reducing the emissions for these processes and one area of research is the carboncapture and storage (CCS) techniques. This report aims to give an overview of existing and emerging CCS techniques applicable for the reheating and heat treating furnaces, along with evaluating one post-combustion carbon capture technique for different cases provided by some involved companies. The carbon capture technique investigated in this project can be divided into three main sections; Oxyfuel combustion, pre-combustion and post-combustion capture. Oxyfuel relies on the usage of pure oxygen instead of air for the combustion of the fuel, this gives a high CO2 concentration in the flue gas (80-98%). Concentrations below 95% require further purification before compression and transportation to storage. Using pre-combustion capture the CO2 is removed before the combustion, this can be done by reformingthe used fossil fuel to a syngas (a gas with a high H2 and CO concentrations). The CO2 is formed by passing the syngas through a water-gas shift, which also increases the H2 concentration further. The CO2 can then be removed relying on reversible chemical reactions or the affinity between the CO2 and an absorbent. The post-combustion carbon capture also relies on reversible chemical reactions or affinity to an absorption medium, usually an amine solvent. The bond is then broken in the desorption unit, creating a pure CO2 stream and a reusable absorbent. The case studies were done only for a post-combustion capture process with a MEA-water solvent (20%) as the absorption medium. The simulation program Aspen Plus was used both for the technicaland economical values, executed by the PhD student Nan Wang at LTU. The values were interpolated/extrapolated nonlinear for each given case. Six different cases were given by four companies, four conventional furnaces and two oxyfuel furnaces. Evaluations for the oxyfuel furnaces were excluded, due to big differences between the model and case values and since the technique evaluated is not implementedat oxyfuel plants. The evaluations done for the conventional furnace cases gave a total cost of between 86 - 126 $/tonne captured CO2. This has to be viewed as a high cost investment even without having a full economic evaluation regarding cost for transportation and storage included.
97

Den gröna betongens framtid : En studie om marknaden för klimatförbättrad betong i förhållande till kommande gränsvärden i klimatdeklarationer / The future of green concrete : A study of the market for climate-improved concrete in relation to future limit values in climate declarations

Sjöblom, Axel, Österberg, Fredrik January 2022 (has links)
Sverige har som mål att senast år 2045 inte ha några nettoutsläpp av växthusgaser till atmosfären. Ett område som diskuteras är byggsektorn och dess utsläpp, vilket har lett till åtgärder i form av införandet av klimatdeklarationer. Dessa ska revideras med krav i form av gränsvärden som förväntas implementeras senast år 2027. Ett område med betydande utsläpp inom byggsektorn är användandet av betong som material vid nybyggnation, varvid intresset av klimatförbättrade varianter har ökat drastiskt under senaste åren.  Denna studie genomförs i samarbete med Wallenstam där det övergripande målet är att identifiera hur marknaden för klimatförbättrad betong står sig gentemot de kommande gränsvärden som förväntas införas till klimatdeklarationer senast år 2027. Ett av målen är att genom en beräkning visa hur en byggnads klimatutsläpp påverkas vid ett användande av klimatförbättrad betong istället för traditionell betong, där ett referensprojekt från Wallenstam har använts. Arbetet ska även, genom en intervjustudie, redogöra för vilka förutsättningar leverantörer av klimatförbättrad betong står inför att ta fram klimatneutral betong. Även om vissa leverantörers produkter gav ett lägre klimatutsläpp än andra visade resultatet ingen större avvikelse hos någon av leverantörerna. Samtliga undersökta leverantörer har produkter som ger ett lägre klimatavtryck än det gränsvärde som är baserat på referensprojektet. Alla undersökta kombinationer av leverantörernas produkter visade ett resultat med en minskning på över 20% där kombinationen med lägst klimatavtryck, som enbart innehåller platsgjuten betong, visade en minskning av byggnadens totala utsläpp på 38.4%. Intervjustudien visade att implementering av CCS-teknik och andra alternativa bindemedel krävs för att nå en klimatneutral betong. / Sweden aims to have zero net emissions of greenhouse gases by the year 2045. A major contributor to emissions is the construction sector, which has led to the introduction of climate declarations. These will be revised with requirements in the form of limit values that are expected to be implemented by the year 2027. As concrete accounts for a large part of the emissions from the construction sector, interest in climate-improved variants has increased significantly in recent years. This study is carried out in collaboration with Wallenstam, where the overall goal is to identify how the market for climate-improved concrete stands in relation to the future limit values that are expected to be introduced in climate declarations by the year 2027. One of the goals is to show how a building's climate emissions are affected by the use of climate-improved concrete instead of traditional concrete. For this, a reference project from Wallenstam has been used. The study will also, through an interview study, account for the conditions that suppliers of climate-improved concrete are facing to produce climate-neutral concrete. Although some suppliers' products had lower climate emissions than others, the results did not show any major deviation at any of the suppliers. All surveyed suppliers have products that have a lower climate footprint than the limit value based on the reference project. All examined combinations of the suppliers' products showed a result with a reduction of over 20%, where the combination with the lowest climate footprint, which only contains cast-in-place concrete, showed a reduction in the building's total emissions of 38.4%. The interview study showed that implementation of CCS technology and other alternative binders is required to reach a climate-neutral concrete.
98

BECCS is next : A study on Bioenergy with Carbon Capture and Storage in Norwegian news media

Persson Skare, Kjersti Maria January 2021 (has links)
Bioenergy with carbon capture and storage is emphasized by the Intergovernmental Panel on Climate Change as a key mitigation option to reach the Paris Agreement goal of 2 degrees Celsius but the required need of large-scale facilities is yet to be developed and is therefore in large theoretical. Norway is one country often portraited as a forerunner in the field especially when it comes to offshore storage. How media is framing the technology can impact how society responds to it. This thesis explores how bioenergy with carbon capture and storage is constructed in Norwegian news media between 2005 and 2020. This is done by conducting a discourse analysis based on Marten Haajers analytical approach and reflect on how the constructed story lines are aligned with the current policy path in Norway. The results show that the three discourses Survivalism, Promethenaism and Ecological modernization have dominated the Norwegian news media and the notion of bioenergy with carbon capture and storage. The majority of published articles in the sample were found to be supportive of the technology but there are also more critical voices who above all advocate an increased focus on the forests’ mitigation potential. The discourses constructed in the news media have clear similarities with the ongoing policy path on bioenergy with carbon capture and storage, as both voice the idea that technological development is well aligned with striving towards sustainability.
99

The Economic Impacts of Technical Change in Carbon Capture

Rasmussen, Peter G. 01 January 2012 (has links) (PDF)
There is a general consensus in the literature that carbon capture and storage (CCS), a technology that controls CO2 emissions from fossil fuel power plants, figures to be a critical technology to reduce CO2 emissions to CO2 concentration stabilization levels prescribed in the literature. We completed three projects that advance the understanding of how technical change in carbon capture affects both near-future costs of CCS and the economy in the long term. First, we conducted a literature review of near-future capture cost estimates in order to get an idea of how expensive carbon capture will be in the near-future. The literature indicates that pre-combustion capture is the least expensive carbon capture technology because its combustion process best facilitates carbon capture. Second, we explored the limits of incremental technical change in each near-future capture technology using a performance-cost model. The results of the sensitivity analysis showed that pre-combustion capture could be the least expensive capture technology after incremental technical change has occurred. Third, we used an integrated assessment model (IAM) to investigate how rapid incremental and breakthrough technical change in carbon capture could impact the electric energy market, total CO2 abatement cost and CO2 price over time. We modeled breakthrough technical change using data from a paper in the literature that provides cost and performance estimates for a radical carbon capture technology still in the early stages of research and development (R&D) (Baker, Chon, & Keisler, 2009). CCS dominates electricity market share over time given a chemical looping breakthrough.
100

Experimental Investigation on Ash Mineralization and Carbon Dioxide Capture and Storage to Meet Gas Grid Limits for Biogas

Sakowski, Bastian Alexander 22 December 2023 (has links)
The present work deals with capture and storage of carbon dioxide from biogases by bond- ing to alkaline earth metals from power plant ashes. The aim is to achieve the feed-in standard in Germany for the natural gas grid by binding CO2 in a long-term stable and environmentally compatible manner. In addition, the ash quality is to be improved by reduced mobility of critical metals such as lead, zinc and cadmium, and calcium carbonate is to be recovered as a valuable material in addition to the biomethane. In several experimental setups from laboratory scale to pilot plant, it was shown that both carbon dioxide and hydrogen sulfide can be captured and stored in large quantities of ash residues. Both the use of a packed column to compensate for the poor absorption and reaction kinetics and the use of ammonium chloride as an extraction agent proved to be particularly effective for biogas upgrading to biomethane level. In contrast, both the absorption and reaction temperature, as well as gas-specific influencing factors such as carbon dioxide concentration and volume flow rate, had little to no influence. With regard to ash quality, an improvement of the landfill class from IV to 0 was achieved with respect to lead, from II to 0 for zinc and from III to I for cadmium. A significant improvement was also achieved for chlorine, but this did not result in a reduction of the landfill class. The ash quantity could be reduced by more than 50 %, among other things, by dissolving out the alkaline earth metals for the carbon dioxide reaction. As further research steps, it remains to further reduce the metal mobility with respect to the ash eluate in order to better optimize the process water quality. This could be achieved, for example, by a controlled pH value.

Page generated in 0.0353 seconds