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- Workshop on "Energy, greenhouse gases and environment" proceedings, presentations and postersPublication . Lemos de Sousa, M. J.; Oliveira, Gisela; Rodrigues, Cristina; Dinis, Maria Alzira Pimenta; Diogo, Miguel Tato; Barros, Nelson
- O Carvão na ActualidadePublication . Lemos de Sousa, M. J.; Rodrigues, Cristina; Dinis, Maria Alzira Pimenta
- Effect of gas compressibility factor estimation in coal sorption isotherms accuracyPublication . Rodrigues, Cristina; da Silva, J.M. Machado; Dinis, Maria Alzira Pimenta; Lemos de Sousa, M. J.Compressibility factor (CF) is a key parameter in gas industry, regarding gas flow and storage in a gas reservoir. This study highlights the necessity to accurately estimate CF, affecting reservoir sorption capacity determination. The effect of the CF of N2, CH4 and CO2 in the coal porous structure was studied. Sorption isotherms showed no significant hysteresis regarding N2, due to gas inert behaviour. CH4 has a higher CF slope and the hysteresis behaviour is stronger than in N2. CO2 has no linear CF behaviour and besides relevant hysteresis, a distinct general trend between both curve shapes was identified, and the CO2 desorption curve intercepted the CO2 adsorption curve at 30x105 Pa. This is due to CO2 retention on coal porous structure, thanks to the great affinity between CO2 and the organic microporous structure, to pressures up to 6.9x105 Pa. The gas mixture showed a significant hysteresis due to its composition.
- Comparative study of the influence of minerals in gas sorption isotherms of three coals of similar rankPublication . Rodrigues, Cristina; Pinheiro, H. J.; Lemos de Sousa, M. J.; yesThis investigation compares the gas adsorption behaviour and capacity of three bituminous coals from South Africa, of similar rank, by assessing the characteristics of the raw coal, as well as the resulting float and sink fractions (at 1.80 cm3/g) obtained by density separation of crushed coal samples. Calculations were also made to obtain the raw coal gas storage capacity from the weighted contribution of both float and sink fractions results, thereby permitting comparison with the analysed results of the raw coal. The study demonstrated that the clean fraction of a coal has the highest capacity to retain gas in the sorbed state, followed by raw coal, and lastly the sink fraction, and re–confirmed previous investigations that showed minerals to be inhibitors of gas adsorption and retention.
- Tecnologias CAC e Inquéritos de Percepção da Opinião Pública sobre “O papel da Captação e do Armazenamento/Sequestração de Dióxido de Carbono no Futuro da Energia na Europa”:O caso-de-estudo da Comunidade Fernando Pessoa: CCS Technologies and Inquiries into Public Perception on “The Role of Carbon Dioxide Capture and Storage in Europe’s Energy Future“ - the case-study of University Fernando Pessoa CommunityPublication . Oliveira, Gisela; Silva, Pedro Nuno; Maia, Rui Leandro; Rodrigues, Cristina; Diogo, Miguel Tato; Dinis, Maria Alzira Pimenta; Ribeiro, Nuno Magalhães; Lemos de Sousa, M. J.O carvão e outros combustíveis fósseis, continuarão a ser, por décadas, a principal matéria-prima energética para as Centrais Térmicas, não obstante os esforços para, dentro do possível, substituir os combustíveis fósseis por fontes de energia renovável.Tal como está, hoje, bem documentado, a produção de gases com efeito estufa (GEE), designadamente CO2, resulta da combustão dos ditos combustíveis fósseis, sendo que se espera ser possível mitigar substancialmente a emissão de tais gases com a aplicação das chamadas Tecnologias Limpas do Carvão.Há, pois, necessidade de promover o abatimento do CO2 através de Tecnologias de Emissão Zero ou Tecnologias Livres de Carbono, incluindo designadamente a Captura, o Transporte e a Sequestração geológica de CO2 correspondentes ao que é costume designar por Tecnologias CAC (Captação e Armazenamento de Carbono). De facto, tais tecnologias e, designadamente, o armazenamento geológico de CO2 são as únicas que, no estado actual do conhecimento, são capazes de permitir que se cumpram as metas do ambicioso programa da EU para a energia e o ambiente conhecido por “20 20 para 2020” em conjugação com os aspectos económicos das directivas relativas ao Comércio Europeu de Licenças de Emissão – CELE (Directivas 2003/87/EC, 2004/101/EC e 2009/29/EC).A importância do tema está, aliás, bem demonstrada com o facto da Comissão Europeia ter formalmente admitido que as metas supracitadas serão impossíveis de atingir sem Sequestração Geológica de CO2. Esta é, pois, uma das razões de ter sido recentemente publicada a Directiva Europeia 2009/31/EC de 23 de Abril de 2009 expressamente dedicada ao tema do Armazenamento Geológico de CO2.Ora, a questão do armazenamento geológico de CO2 implica, para além das Tecnologias CAC acima mencionadas e da sua viabilização em termos tanto técnicos como económicos, ou seja, neste último aspecto, competitiva com o sistema CELE, também o conhecimento, da percepção pública sobre o assunto. Isto é, a praticabilidade das Tecnologias CAC implica que se conheça a opinião pública sobre o tema e, naturalmente, que face a esta realidade se prestem os esclarecimentos necessários como, aliás, é reconhecido na própria Directiva Europeia 2009/31/EC.Dado que a Fundação Fernando Pessoa / Universidade Fernando Pessoa através do seu Centro de Investigação em Alterações Globais, Energia, Ambiente e Bioengenharia – CIAGEB tem ultimado um Projecto de Engenharia relativo à Sequestração Geológica de CO2 nos Carvões (Metantracites) da Bacia Carbonífera do Douro – o Projecto COSEQ, preocupou-se naturalmente, desde o início, com o lançamento de inquéritos de percepção da opinião pública sobre o assunto.Tal implicou, nesta fase, a tradução para português e o lançamento do inquérito europeu ACCSEPT que não tinha sido ainda formalmente lançado de forma generalizada entre nós. Antes, porém, de lançar publicamente tal inquérito – o que está actualmente já em curso – resolveu-se testar o método de lançamento, a recolha de dados e o seu tratamento com uma amostra correspondente ao que se designou por Comunidade Fernando Pessoa, i.e. o conjunto de docentes, discentes, funcionários e outras pessoas relacionadas com a Universidade Fernando Pessoa (cerca de 5000 individualidades).Este trabalho diz, precisamente, respeito à preparação, lançamento e análise dos resultados do dito inquérito Europeu ACCSEPT a nível da Comunidade Fernando Pessoa. Foram recebidas 525 respostas representando 10,5% da amostra. A análise de resultados foi sistematicamente comparada com os obtidos nos outros países europeus, através do projecto ACCSEPT e, bem assim, com os resultados obtidos num inquérito homólogo lançado no Brasil. The use of coal, and other fossil fuels, will remain for decades as the main source of energy for power generation, despite the important efforts made to replace, as far as possible, fossil fuels with renewable power sources.As is well documented, the production of Greenhouse Gases (GHG), mainly CO2, arises primarily from the combustion of fossil fuels. The increasing application of Clean Coal Technologies-CCTs, is expected to mitigate substantially against the emission of such gases.There is consequently a need to promote the CO2 abatement through Zero Emission (Carbon Free) Technologies - ZETs, which includes CO2 capture, transport and geological storage, i.e. the so-called CCS (Carbon, Capture and Storage) technologies. In fact, these technologies are the only ones that are presently able to conform to the ambitious EU targets set out under the “20 20 by 2020” EU energy and environment programme, jointly with the economic aspects of the EU Directives 2003/87/EC, 2004/101/EC and 2009/29/EC concerned with the Greenhouse Gas Emissions Allowance Trading Scheme – ETS scheme. The European Commission formal admission that the referred targets will be impossible to reach without the implementation and contribution of geological storage clearly demonstrate the importance of this particular issue, and for this reason the EC Directive 2009/31/EC of April 23, 2009 on Geological Storage of CO2 was recently published.In considering the technical and economical viabilities of CCS technologies, the latter in competition with the ETS scheme, it is believed that public perception will dictate the success of the development and implementation of CO2 geological storage at a large industrial level. This means that, in order to successfully implement CCS technologies, not only must public opinion be taken into consideration but objective information must also be provided to the public in order to raise subject awareness, as recognized in the referred Directive 2009/31/EC.In this context, the Fernando Pessoa Foundation / University Fernando Pessoa, through its CIAGEB (Global Change, Energy, Environment and Bioengineering) RDID&D Unit, is the sponsor of an Engineering Project for the Geological Sequestration of CO2 in Douro Coalfield Meta-anthracites - the COSEQ Project, and is therefore also engaged in public perception surveys with regards to CCS technologies.At this stage, the original European ACCSEPT inquiry was translated to Portuguese and submitted only to the “Fernando Pessoa Community” - comprising university lecturers, students, other employees, as well as, former students and persons that have a professional or academic relationship with the university (c. 5000 individuals). The results obtained from this first inquiry will be used to improve the survey informatics system in terms of communication, database, and data treatment prior to resubmission of the inquiry to the Portuguese public at large.The present publication summarizes the process and the results obtained from the ACCSEPT survey distributed to the “Fernando Pessoa Community”. 525 replies, representing 10.5% of the sample, have been received and analysed. The assessment of the results was systematically compared with those obtained from other European Countries, as reported by the ACCSEPT inquiry, as well as with those from an identical inquiry launched in Brazil.
- Overview CO2 Geological SequestrationPublication . Lemos de Sousa, M. J.; Rodrigues, Cristina; Dinis, Maria Alzira Pimenta; Oliveira, Gisela
- The measurement of coal porosity with different gasesPublication . Rodrigues, Cristina; Lemos de Sousa, M. J.Sorption processes can be used to study different characteristics of coal properties, such as gas content (coalbed methane potential of a deposit), gas diffusion, porosity, internal surface area, etc. Coal microstructure (porosity system) is relevant for gas flow behaviour in coal and, consequently, directly influences gas recovery from the coalbed. This paper addresses the determination of coal porosity (namely micro- and macroporosity) in relation to the molecular size of different gases. Experiments entailed a sorption process, which includes the direct method of determining the ‘‘void volume’’ of samples using different gases (helium, nitrogen, carbon dioxide, and methane). Because gas behaviour depends on pressure and temperature conditions, it is critical, in each case, to know the gas characteristics, especially the compressibility factor. The experimental conditions of the sorption process were as follows: temperature in the bath 35 ºC; sample with moisture equal to or greater than the moisture-holding capacity (MHC), particle size of sample less than 212 mm, and mass ca. 100 g. The present investigation was designed to confirm that when performing measurements of the coal void volume with helium and nitrogen, there are only small and insignificant changes in the volume determinations. Inducing great shrinkage and swelling effects in the coal molecular structure, carbon dioxide leads to ‘‘abnormal’’ negative values in coal void volume calculations, since the rate of sorbed and free gas is very high. In fact, when in contact with the coal structure, carbon dioxide is so strongly retained that the sorbed gas volume is much higher than the free gas volume. However, shrinkage and swelling effects in coal structure induced by carbon dioxide are fully reversible. Methane also induces shrinkage and swelling when in contact with coal molecular structure, but these effects, although smaller than those induced by carbon dioxide, are irreversible and increase the coal volume.
- The coal cleat system: A new approach to its studyPublication . Rodrigues, Cristina; Laiginhas, C.; Fernandes, M.; Lemos de Sousa, M. J.; Dinis, Maria Alzira PimentaAfter a general analysis regarding the concept of coal “cleat system!”, its genetic origin and practical application in Coalbed methane (CBM) commercial production and in CO2 geological sequestration projects, the authors have developed a method to answer, quickly and accurately according with the industrial practice and needs, to the following yet unanswered questions: (i) how to define the spatial orientation of the different classes of cleats present in a coal seam, and (ii) how to determine the frequency of their connectivites? The new available and presented techniques to answer these questions have a strong computer based tool (Geographic Information System (GIS)), able to build a complete georeferentiated database, which will allow to three-dimensionally locate the laboratory samples in the coalfield. It will also allow to better understand the coal cleat system and consequently to recognise the best pathways to gas flow through the coal seam. Such knowledge is considered crucial for understanding what is likely to be the most efficient opening of cleat network, then allowing the injection with the right spatial orientation, of pressurized fluids or propants in order to directly drain the maximum amount of gas flow to a CBM exploitation well. The method is also applicable to the CO2 Geological Sequestration Technologies, operations corresponding to the injection of CO2 sequestered from industrial plants in coal seams of abandoned coalmines or high depth coal seams.
- Gas Storage versus Gas Circulation in North Atlantic and Gondwana Coal TypesPublication . Dinis, Maria Alzira Pimenta; Rodrigues, Cristina; Lemos de Sousa, M. J.The growing insufficiency in oil and natural gas supplies and the rise in energy consumption all over the world have created new opportunities to other energy products and technologies. Coal acquired again an important role in the global energy survey. International Organizations are nowadays conscious and compromised to systematically move into Clean/Cleaner Coal Technologies (CCTs) and, above all, into Zero (or near zero) Emission Technologies (ZETs). Carbon Capture and Storage (CCS) Technologies, acting in a complementary way to CCTs, are becoming one of the solutions to face Climate Changes, permitting not to avoid but to minimize at an acceptable level the Green House Gas Effect (GHGE). It is also imperative to emphasize the actual crucial role of coal as a natural gas source rock and as a reservoir. Yet it is also important to understand that when coal has a high gas generation potential this fact does not necessarily imply that coal also has a high gas storage capacity and a high gas circulation performance. This investigation aims to compare the gas storage capacity and the gas circulation behaviour between Gondwana and North-Atlantic coal types. Two sets of Gondwana and North-Atlantic coal types, with different ranks, were selected in the present research. Results revealed that the two sets of samples, corresponding to different facies and, consequently, with different chemical and physical properties, have quite different gas storage and gas circulation behaviours. In general terms, “North-Atlantic Type” coals have a higher CH4 storage capacity than “Gondwana Type” coals, due to differences in their petrographic characteristics, mainly in terms of vitrinite content, and rank but also, although in a smaller scale, in terms of gas sorption temperatures. Diffusion coefficient values present a higher dependency on temperature changes than on gas storage capacities due to the high activation energy induced by high temperatures.
- Coal gas adsorption/desorption isotherms versus diffusion processPublication . Rodrigues, Cristina; Dinis, Maria Alzira Pimenta; Lemos de Sousa, M. J.In the present work, the authors studied two meta-anthracite samples from Douro Coalfield (NW of Portugal) in which classical sorption isotherms were carried out, using CO2 only. Results have demonstrated that whenever the CO2 is adsorbed in the coal pores/matrix it will be enduringly fixed up to, approximately, pressures of 32 bar in sample A and 34 bar in sample B. Since the gas release process it intensely related to diffusion coefficients, it is crucial to define their evolution on the two analyses reported in this paper. So, during adsorption, diffusion coefficients decrease in sample A from 4.66736E-08 to 1.23490E-09 cm2/sec (6.72 and 48.13 bar) and during desorption they increase from 7.61829E-09 to 1.09908E-08 cm2/sec (45.68 and 11.48 bar). In sample B, diffusion coefficients decrease from 2.47409E-08 to 2.11813E-09 cm2/sec (7.53 and 47.17 bar) in adsorption and increase in desorption from 1.48767E-09 to 2.83736E-08 cm2/sec (42.22 and 7.71 bar).
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