• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 16
  • 14
  • 10
  • 4
  • 4
  • 1
  • Tagged with
  • 52
  • 52
  • 28
  • 14
  • 12
  • 11
  • 9
  • 9
  • 8
  • 7
  • 7
  • 6
  • 6
  • 6
  • 5
  • 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.
1

Cogeração: Uma Alternativa para Produção de Eletricidade / COGENERATION: AN ALTERNATIVE FOR PRODUCTION OF ELECTRICITY

Oddone, Domingos Carlos 31 January 2002 (has links)
O objetivo deste trabalho é demonstrar por que a cogeração não se desenvolve no Brasil, mesmo apresentando-se como alternativa para produção de eletricidade. Entretanto existem vários estímulos por parte do Estado para a implantação de grandes termoelétricas no país. Será apresentada a análise dos processos de cogeração, envolvendo: as alternativas tecnológicas, a viabilidade econômica, e as questões ambientais, chegando-se a um quadro indicando a sensibilidade aos diversos parâmetros econômicos que fazem parte dos projetos de cogeração. Serão mostrados cenários com a visão de futuro, indicando diferentes opções que permitam o crescimento do mercado de energia no Brasil, de uma forma mais segura. No momento em que o Brasil passa por profundas mudanças no setor energético, incluindo a necessidade da expansão do parque gerador e considerando que parte importante dessa expansão será através de grandes centrais termoelétricas, torna-se importante apresentar uma alternativa de produção de eletricidade, no Brasil ainda pouco explorada, que é a cogeração. Este trabalho irá mostrar que com maior incentivo aos projetos de cogeração, através de uma política energética nacional adequada, se pode produzir parcela importante da energia elétrica para o atendimento das necessidades crescentes da sociedade brasileira, com menor impacto ambiental e econômico, refletindo em menor custo final da energia produzida. / The aim of this paper is to show why the CHP does not develop in Brazil, even presenting itself as an alternative to producing electricity. However there are several incentives from the state for the deployment of large power plants in the country. You will see the analysis of cogeneration processes, involving: the technological alternatives, the economic viability and environmental issues, coming to a table showing the sensitivity to various economic parameters that are part of cogeneration projects. Scenarios are shown with the vision of the future, indicating different options that allow for growth of the energy market in Brazil, a more secure way. At the moment Brazil is going through profound changes in the energy sector, including the need for expansion of generating facilities and considering that an important part of this expansion will be through large power plants, it is important to present an alternative electricity production in Brazil still little explored, which is cogeneration. This paper will show that with greater encouragement to cogeneration projects through an adequate national energy policy, it can produce substantial amount of electricity to meet the growing needs of Brazilian society, with less environmental impact and economic development, reflecting a lesser cost final energy produced.
2

The incorporation of environmental costs into power system planning in Brazil

Furtado, Ricardo Cavalcanti January 1996 (has links)
No description available.
3

Cogeração: Uma Alternativa para Produção de Eletricidade / COGENERATION: AN ALTERNATIVE FOR PRODUCTION OF ELECTRICITY

Domingos Carlos Oddone 31 January 2002 (has links)
O objetivo deste trabalho é demonstrar por que a cogeração não se desenvolve no Brasil, mesmo apresentando-se como alternativa para produção de eletricidade. Entretanto existem vários estímulos por parte do Estado para a implantação de grandes termoelétricas no país. Será apresentada a análise dos processos de cogeração, envolvendo: as alternativas tecnológicas, a viabilidade econômica, e as questões ambientais, chegando-se a um quadro indicando a sensibilidade aos diversos parâmetros econômicos que fazem parte dos projetos de cogeração. Serão mostrados cenários com a visão de futuro, indicando diferentes opções que permitam o crescimento do mercado de energia no Brasil, de uma forma mais segura. No momento em que o Brasil passa por profundas mudanças no setor energético, incluindo a necessidade da expansão do parque gerador e considerando que parte importante dessa expansão será através de grandes centrais termoelétricas, torna-se importante apresentar uma alternativa de produção de eletricidade, no Brasil ainda pouco explorada, que é a cogeração. Este trabalho irá mostrar que com maior incentivo aos projetos de cogeração, através de uma política energética nacional adequada, se pode produzir parcela importante da energia elétrica para o atendimento das necessidades crescentes da sociedade brasileira, com menor impacto ambiental e econômico, refletindo em menor custo final da energia produzida. / The aim of this paper is to show why the CHP does not develop in Brazil, even presenting itself as an alternative to producing electricity. However there are several incentives from the state for the deployment of large power plants in the country. You will see the analysis of cogeneration processes, involving: the technological alternatives, the economic viability and environmental issues, coming to a table showing the sensitivity to various economic parameters that are part of cogeneration projects. Scenarios are shown with the vision of the future, indicating different options that allow for growth of the energy market in Brazil, a more secure way. At the moment Brazil is going through profound changes in the energy sector, including the need for expansion of generating facilities and considering that an important part of this expansion will be through large power plants, it is important to present an alternative electricity production in Brazil still little explored, which is cogeneration. This paper will show that with greater encouragement to cogeneration projects through an adequate national energy policy, it can produce substantial amount of electricity to meet the growing needs of Brazilian society, with less environmental impact and economic development, reflecting a lesser cost final energy produced.
4

Elproduktion från överskottsånga i en kondensturbin : En lönsamhets- och miljöbedömning / Electricity production from excess steam in a condensing turbine : An economic feasibility and environmental assessment

Ternström, Linus, Gustafsson, Linnéa January 2016 (has links)
Den stora användningen av fossil energi i världen är en av orsakerna till de höga utsläppen av koldioxid som förstärker växthuseffekten. För att minska människans klimatpåverkan bör därför mer förnyelsebar energi användas. EU har därför som mål att minska utsläppen av koldioxid med 40 % till år 2030. Industrisektorn står för 32 % av världens totala energianvändning och pappers- och massaindustrin använder 6 % av den energin. I denna studie undersöks Stora Enso Skoghalls Bruk som är ett pappers- och massabruk beläget norr om Vänern. De senaste åren har en rad energieffektiviserande åtgärder utförts där som gjort att det tidvis produceras ett överskott av ånga. I dagsläget friblåses överskottsångan för att hålla trycket på deras ångnät på avsedd nivå. Studiens syfte är att undersöka om elproduktion med hjälp av en kondensturbin är ett lönsamt alternativ för att ta till vara på överskottsångan istället för att friblåsa den. Målet är att ta fram ett beslutsunderlag för dimensionering och bedömning av lönsamhet samt miljöpåverkan för en kondensturbin på Skoghalls Bruk. Studien utfördes genom energitekniska beräkningar i Simulink och en lönsamhetsbedömning genom en nuvärdesanalys. Som grund till beräkningarna ligger driftdata och vetenskaplig litteratur. Scenarier har konstruerats för att avgöra hur både elpriser och koldioxidalstring knuten till den nordiska elmarknaden kan se ut i framtiden. Den samlade bedömningen av studien är att Skoghalls Bruk inte bör investera i en kondensturbin i dagsläget. Låga elpriser i kombination med höga bränslepriser gör att vinsten inte blir tillräckligt hög i förhållande till investeringskostnaden. Vid mer gynnsamma förhållanden, alltså med högre elpriser, lägre bränslekostnader och låg ränta är det mer troligt att investeringen blir lönsam. Investeringen är dock lönsam ur ett miljöperspektiv så länge kondensturbinens elproduktion ersätter någon form av fossil elproduktion i Norden. / The high use of fossil energy in the world is one of the causes of the high emissions of carbon dioxide, which increases the greenhouse effect. In order to reduce the anthropogenic climate impact, more renewable energy should be used. The EU aims to reduce carbon dioxide emissions by 40 % by the year 2030. The industrial sector accounts for 32 % of the total world energy consumption of which the pulp and paper industry uses 6 %. This study examines Stora Enso Skoghall Mill which is a pulp and paper mill located north of Vänern. In recent years, a series of energy efficiency measures has been carried out at Skoghall Mill. At times these measures have resulted in a surplus of steam production. Today this excess steam is released to the atmosphere to maintain the pressure on the steam network at the required level. The purpose of this study is to investigate whether electricity production using a condensing turbine is a profitable alternative for recovery of the excess steam which is currently being released to the atmosphere. The aim is to develop a decision basis for the design and assessment of profitability and environmental impact of a condensing turbine at Skoghall Mill. The study was conducted through energy calculations in Simulink and a profitability assessment by a present value analysis. The basis for the calculations is operational data provided by Skoghall Mill and scientific literature. Scenarios have been designed to determine both how electricity prices and generation of carbon dioxide linked to the Nordic electricity market might look in the future. The overall conclusion of the study is that Skoghall Mill should not invest in a condensing turbine at this time. The profit is not high enough compared to the investment cost due to low electricity prices combined with high fuel costs. In more favourable conditions, i.e. with higher electricity prices, lower fuel costs and lower interest rates, it is more likely that the investment will be profitable. The investment, however, is profitable from an environmental perspective, as long as the electricity from the condensing turbine is replacing fossil power generation in the Nordic region.
5

Who invests in renewable electricity production? Empirical evidence and suggestions for further research

Bergek, Anna, Mignon, Ingrid, Sundberg, Gunnel January 2013 (has links)
Transforming energy systems to fulfill the needs of a low-carbon economy requires large investments in renewable electricity production (RES-E). Recent literature underlines the need to take a closer look at the composition of the RES-E investor group in order to understand the motives and investment processes of different types of investors. However, existing energy policies generally consider RES-E investments made on a regional or national level, and target investors who evaluate their RES-E investments according to least-cost high-profit criteria. We present empirical evidence to show that RES-E investments are made by a heterogeneous group of investors, that a variety of investors exist and that their formation varies among the different types of renewable sources. This has direct implications for our understanding of the investment process in RES-E and for the study of motives and driving forces of RES-E investors. We introduce a multi-dimensional framework for analyzing differences between categories of investors, which not only considers to the standard economic dimension which is predominant in the contemporary energy literature, but also considers the entrepreneurship, innovation-adoption and institutional dimensions. The framework emphasizes the influence of four main investor-related factors on the investment process which should be studied in future research: motives, background, resources and personal characteristics. / <p>Highlights</p><p>► The RES-E investor group is heterogeneous. ► Investors with no traditional background within electricity production make the majority of RES-E investments in Sweden. ► Different types of RES-E investors invest in different renewables. ► A standard economic perspective is not sufficient to understand emerging RES-E investors. ► Motives, background, resources and personal characteristics of RES-E investors matter.</p> / NYEL - Nya investerare i förnybar elproduktion
6

Scenarios for future power balance in bidding zone 3 in Sweden year 2040.

Caliskan, Hevi January 2020 (has links)
This is a master thesis performed on behalf of WSP, aiming to investigate scenarios for future energy balances in bidding zone 3 in Sweden during year 2040, based on different production alternatives and consumption scenarios. This report aims to highlight the challenges of transitioning to a more electrified energy system where a greater proportion of renewable sources, mainly from hydro, wind, solar and bioenergy, are integrated into the energy system. Increasing the share of weather-dependent electricity production, such as solar- and wind power, set higher standard on the ability to maintain system balance and guaranteeing sufficient power when consumption is high. Higher consumption will be caused by increased electrification of different sectors, and urbanization, which will be necessary in order to achieve climate goals. Production from other power sources, import of electricity from other bidding zones, and flexibility will have to be considered when the demand for electricity cannot be met by solely the production that takes place in bidding zone 3. In this study, EXCEL is used to build a model that calculates future energy balances and presents the extent that future imports of electricity and flexibility, that will be needed to supply enough electricity to bidding zone 3 in the year 2040. With four different production alternatives and three consumption scenarios, 12 different cases of future energy balances are presented.
7

Assessment of geothermal application for electricity production from the prairie evaporite formation of Williston Basin in South-West Manitoba

Firoozy, Niloofar 10 1900 (has links)
In this thesis, the potential of enhanced geothermal system to provide adequate energy to a 10 MW electricity power plant from Prairie Evaporite Formation of Williston Basin was investigated. This formation partly consists of halite with low thermal resistance and high thermal conductivity, which translates into a lower drilling length to reach the desired temperature, comparing to other rock types. To this end, two numerical models with experimental data in south-west Manitoba (i.e. Tilston) and south-east Saskatchewan (i.e. Generic) were designed. The thermal reservoirs were located at 1.5 km (Tilston site) and 3 km (Generic site) with approximate thicknesses of 118 m. Considering an injection brine of 6% NaCl at 15°C, the final derived temperature at wellhead of the production wells were 43°C and 105°C respectively. Finally, the Generic site was concluded as a suitable candidate for electricity production by providing higher surfaced fluid temperature than the minimum of 80°C. / February 2017
8

Analysis of metatranscriptomes from an acidophilic electricity generating community treating acidic mining wastewaters

Palma, Daniela January 2018 (has links)
Human ́s constant need for metals requires unsustainable mining and refining of metalore. As a result, highly contaminated wastewaters are discharged in the environmentcompromising the nearby habitat together with all its life forms. Microbial fuel cells arebioelectrochemical systems (BES’s) that use microorganisms to convert organic andinorganic matter, producing electricity as the final product. This technology has shownto have great potential for application for bioremediation of wastewaters. This thesisdescribes the gene expression and the taxonomical abundance of an acidophilic,electricity generating community that was used to treat mining wastewaters in amicrobial fuel cell. A complete metatranscriptomics analysis has been performed onduplicate MFC anode acidophilic microbial community generating electricity frominorganic sulfur compounds (ISC) oxidation at extremely low pH. The analysis showsthat the most expressed genus is Ferroplasma-like, the genus Acidithiobacillus-like isfollowing along with Sulfobacillus-like and Thermoplasma-like. Some of the generaexpressed show behaviours never described before suggesting that potentially, newspecies have been selected. The reactions of the sulfur pathway are regulated mostly bytwo genera: Acidithiobacillus-like during the disproportionation of tetrathionate, andFerroplasma-like by expressing the hdr gene that catalyses the reaction from elementalsulfur to sulfite, the sulfite is then converted to sulfate. The hdr gene has not previouslybeen found in F. acidarmanus-like suggesting that the specie might have been selectedfor this trait. Acidithiobacillus-like genus has a bigger role for the energy conservationand the electron transport in the sample, however the data are not sufficient to point outwhich gene has the major role in the process. The CO2 fixation in the chamber wasconsiderably low as a result from a significant carboxysomes production, bacterialcompartiments involved in the carbon dioxide fixation. The transcripts abundanceregarding the metal resistance genes have shown low expression suggesting that thecells were not under stress. This result is indicated by the synthesis of a transcriptionalrepressor protein that had prevented a significant production of metal resistanceenzymes. Likewise, the pH homeostasis plot does not show vast transcripts abundances,indicating that the cells were thriving under conditions not far from the optimum.
9

The electricity system vulnerability of selected European countries to climate change : A comparative analysis

Klein, Daniel R. January 2012 (has links)
The electricity system is particularly susceptible to climate change due to the close interconnectedness between not only electricity production and consumption to climate, but also the interdependence of many European countries in terms of electricity imports and exports. This study provides a country based relative analysis of a number of selected European countries’ electricity system vulnerability to climate change. Taking into account a number of quantitative influencing factors, the vulnerability of each country is examined both for the current system and using some projected data. Ultimately the result of the analysis is a relative ranked vulnerability index based on a number of qualitative indicators. Overall, countries that either cannot currently meet their own electricity consumption demand with inland production (Luxembourg), or countries that experience and will experience the warmest national mean temperatures, and are expected to see increases in their summer electricity consumption are found to be the most vulnerable for example Greece and Italy. Countries such as the Czech Republic, France and Norway that consistently export surplus electricity and will experience decreases in winter electricity consumption peaks were found to be the least vulnerable to climate change. The inclusion of some qualitative factors however may subject their future vulnerability to increase. The findings of this study enable countries to identify the main factors that increase their electricity system vulnerability and proceed with adaptation measures that are the most eective in decreasing vulnerability.
10

Parallel-Powered Hybrid Cycle with Superheating “Partially” by Gas Turbine Exhaust

Ghasemi, Milad, Hammodi, Hassan, Moosavi Sigaroodi, Homan January 2014 (has links)
It is of great importance to acquire methods that has a sustainable solution for treatment and disposal of municipal solid waste (MSW). The volumes are constantly increasing and improper waste management, like open dumping and landfilling, causes environmental impacts such as groundwater contamination and greenhouse gas emissions. The rationalization of developing a sustainable solution implies in an improved way of utilizing waste resources as an energy source with highest possible efficiency. MSW incineration is by far the best available way to dispose the waste. One drawback of conventional MSW incineration plants is that when the energy recovery occurs in the steam power cycle configuration, the reachable efficiency is limited due to steam parameters. The corrosive problem limits the temperature of the superheated steam from the boiler which lowers the efficiency of the system. A suitable and relatively cheap option for improving the efficiency of the steam power cycle is the implementation of a hybrid dual-fuel cycle. This paper aims to assess the integration of an MSW incineration with a high quality fuel conversion device, in this case natural gas (NG) combustion cycle, in a hybrid cycle. The aforementioned hybrid dual-fuel configuration combines a gas turbine topping cycle (TC) and a steam turbine bottoming cycle (BC). The TC utilizes the high quality fuel NG, while the BC uses the lower quality fuel, MSW, and reaches a total power output of 50 MW.  Using a high-quality fuel in cogeneration can prove to be beneficial for improving and enhancing the overall plant profitability and efficiency while eliminating the corrosion problems with conventional MSW firing. The need for few interconnections between the different subunits in a parallel-fueled system allows for a wider range of operation modes and leaves room for service modes of the subunit. The hybrid dual-fuel cycle will be assessed for optimal cycle configuration and evaluated to how it compares to the sum of two separate single-fuel plants with optimal cycle configurations. Investigation of such aspects is a very important issue in order to be able to fully promote an implementation of hybrid combined cycle. The work presented herein also concentrates on investigating scenarios that include a full-load and part-load analysis in both condensing and combined heat and power (CHP) mode of operation. Through simulations and evaluation of obtained data, the results strengthens the fact that the electrical efficiency of hybrid configurations increases at least with 2% in condensing mode and 1,5% in CHP mode, comparing it to the sum of two separate single-fuel units of similar scale. The simulations show increased electrical efficiencies when running the BC in part-load and the TC in full load, with a higher NG to MSW ratio. The results also indicated that it is possible to extract more power output from the cycle by operating in CHP mode, due to more energy being utilized from the input fuel.

Page generated in 0.1155 seconds