942 resultados para Greenhouse gardening.
Resumo:
Late Cenozoic has witnessed a series of climate-environmental change which ends with a transitional shift from greenhouse to icehouse conditions. In last two decades, scientists began to employ the tectonic uplift and its weathering effect to interpret the climatic changes during the late Cenozoic. However, this endeavor has partly been restricted by the lacking of regional and global chemical weathering data. The loess-red clay deposit in the Loess Plateau may record the weathering features of the detritus material from the wide range upwind of the Loess Plateau. Therefore geochemistry of the loess-plaeosol and red clay sequences may provide insights into the regional chemical weathering regime and the connection between the chemical weathering and the late Cenozoic climate-environmental change Here we selected 319 samples from the Baishui section near the Pingliang City, Gansu Province, and analyzed them with X-ray fluorescence. Based on the result, we reconstruct the chemical weathering history of the Baishui section since 6Ma. We chose CIA as the proxy for chemical weathering intensity. The CIA ratio in soil units is higher than in adjacent loess horizons, but lower than in the red clay, in good agreement with the field observation. The CIA ratios of the Baishui section correlates well with the global ice volume fluctuations, indicating that the global cooling may contribute a lot to the chemical weathering variations in Chinese Loess Plateau. There are at least 3 million-year time scale variations that can be identified in the chemical weathering intensity curve, i.e., between 3.3 to 2.1 Ma, 1.7 to 0.9 Ma and from 0.9Ma. We think these may reflect the combined effect of the tectonic uplift and ice sheets on monsoon intensity. Other time scale variations can be also observed. In the period between 2.4 and 0.8 Ma, the CIA record display the 400,000 years cycle, which may be resulted from the Tibetan uplift during the Pliocene-early Pleistocene which have significantly amplified the monsoon response sensitivity to the orbital-scale variations in insolation. From 1.2 Ma, the 100,000 years period became intensifying, and particularly after 0.8 Ma, the earlier monsoon response at 400,000 year periodicity was overwhelmed by the ice sheet forcing at 100,000 year periodicity. These may indicate that the expansions of the Northern Hemisphere ice sheets may have crossed a threshold, which enforce the monsoon responding at the 100,000 year periodicity.
Resumo:
There has been a growing concern about the use of fossil fuels and its adverse effects on the atmospheric greenhouse and ecological environment. A reduction in the release rate of CO2 into the atmosphere poses a major challenge to the land ecology of China. The most promising way of achieving CO2 reduction is to dispose of CO2 in deep saline aquifers. Deep aquifers have a large potential for CO2 sequestration in geological medium in terms of volume and duration. Through the numerical simulation of multiphase flow in a porous media, the transformation and motion of CO2 in saline aquifers has been implemented under various temperature and hydrostatic pressure conditions, which plays an important role to the assessment of the reliability and safety of CO2 geological storage. As expected, the calculated results can provide meaningful and scientific information for management purposes. The key problem to the numerical simulation of multiphase flow in a porous media is to accurately capture the mass interface and to deal with the geological heterogeneity. In this study, the updated CE/SE (Space and time conservation element and solution element) method has been proposed, and the Hybrid Particle Level Set method (HPLS) has extended for multiphase flows in porous medium, which can accurately trace the transformation of the mass interface. The benchmark problems have been applied to evaluate and validate the proposed method. In this study, the reliability of CO2 storage in saline aquifers in Daqingzi oil field in Sunlong basin has been discussed. The simulation code developed in this study takes into account the state for CO2 covering the triple point temperature and pressure to the supercritical region. The geological heterogeneity has been implemented, using the well known geostatistical model (GSLIB) on the base of the hard data. The 2D and 3D model have been set up to simulate the CO2 multiphase flow in the porous saline aquifer, applying the CE/SE method and the HPLS method .The main contents and results are summarized as followings. (1) The 2D CE/SE method with first and second –order accuracy has been extended to simulate the multiphase flow in porous medium, which takes into account the contribution of source and sink in the momentum equation. The 3D CE/SE method with the first accuracy has been deduced. The accuracy and efficiency of the proposed CE/SE method have been investigated, using the benchmark problems. (2) The hybrid particle level set method has been made appropriate and extended for capturing the mass interface of multiphase flows in porous media, and the numerical method for level set function calculated has been formulated. (3) The closed equations for multiphase flow in porous medium has been developed, adept to both the Darcy flow and non-Darcy flow, getting over the limitation of Reynolds number to the calculation. It is found that Darcy number has a decisive influence on pressure as well as velocity given the Darcy number. (4) The new Euler scheme for numerical simulations of multiphase flows in porous medium has been proposed, which is efficient and can accurately capture the mass interface. The artificial compressibility method has been used to couple the velocities and pressure. It is found that the Darcy number has determinant effects on the numerical convergence and stability. In terms of the different Darcy numbers, the coefficient of artificial compressibility and the time step have been obtained. (5) The time scale of the critical instability for critical CO2 in the saline aquifer has been found, which is comparable with that of completely CO2 dissolved saline aquifer. (6) The concept model for CO2 multiphase flows in the saline aquifer has been configured, based on the temperature, pressure, porosity as well as permeability of the field site .Numerical simulation of CO2 hydrodynamic trapping in saline aquifers has been performed, applying the proposed CE/SE method. The state for CO2 has been employed to take into account realistic reservoir conditions for CO2 geological sequestration. The geological heterogeneity has been sufficiently treated , using the geostatistical model. (7) It is found that the Rayleigh-Taylor instability phenomenon, which is associated with the penetration of saline fluid into CO2 fluid in the direction of gravity, has been observed in CO2 multiphase flows in the saline aquifer. Development of a mushroom-type spike is a strong indication of the formation of Kelvin-Helmholtz instability due to the developed short wavelength perturbations present along the interface and parallel to the bulk flow. Additional key findings: the geological heterogeneity can distort the flow convection. The ascending of CO2 can induce the persistent flow cycling effects. The results show that boundary conditions of the field site have determinant effects on the transformation and motion of CO2 in saline aquifers. It is confirmed that the proposed method and numerical model has the reliability to simulate the process of the hydrodynamic trapping, which is the controlling mechanism for the initial period of CO2 storage at time scale of 100 years.
Resumo:
Widespread black chert-shales occur in the Ediacaran-Cambrian(E-C) boundary successions along the flank of Yangtze Platform, South China, remarkable changes in sedimentology, geochemistry and biology were recorded. Although extensive studies were carried out upon this boundary succession, the origin of black chert-shales still remain controversial. This paper focuses on the E-C black chert-shales in western Hunan, South China, upon which detailed depositional and geochemical changes are documented, accordingly a depositional model for black chert-shales is proposed. Stratigraphic anatomy across the depositional strike demonstrates that the shallow-water Dengying dolostone along the platform margin sharply pass basinward into the Liuchapo chert successions, which indicate syndepositional extensional faulting at depth could have occurred along the platform margin. The deep-water Niutitang phosphorite-rich black shales are either underlain by the Dengying dolostones on the platform margin toward platform interior or directly by the Liuchaopo chert successions farther basinwards. By detailed investigation, silica chimneys are firsly identified approximately in the chert along platform margin; two types of silica chimneys, including mounded and splayed/funnelized chert(generally brecciated) bodies are further sorted out. The mounded chert are exitbited by domed or hummocky surfaces on the top and irregular spongy to digitiform internal fabrics; within the silica mounds, abundant original vesicles/voids and/or channels were mostly plugged by initial chalcedony, quartze crystals with minor dolomite and bladed barite crystals. Splayed/funnelized brecciated chert “intrusion” cross-cut the uppermost dolostones capping to the horizon underneath, and are directly overlain by the Niutitang phosphorite-rich black shales. Their similarities to the silica chimneys reported from the oceanic spreading centres suggest a similar origin responsible for these unique silica bodies which is also supported by the microthermonmetric data and element geochemistry. High P, Ba, Fe contents and positive correlation between Fe and TOC concentrations in the Niutitang black shales indicate a high palaeo-productivity in the Early Cambrian ocean. The low Th/U and the high V/Cr, V/Sc, V/(V+Ni) ratios in the black shales suggest an anoxic water condition during this interval. Furthermore, Positive Eu anomalies and high Ba contents in the sediments also imply a hydrothermal influence on the formation of Niutitang black shales. To better constrain the placement of deep-water successions straddling the E-C boundary and the timing of hydrothermal silica chimneys, sensitive high-resoluton ion microprobe(SHRIMP) U-Pb dating of zircon grains from tuffs within the chert succession of Liuchapo Formation at Ganziping was conducted and yields a weighted-mean 206Pb/238Pb age at 536.6±5.5Ma, younger than E-C boundary age(542.0±0.3Ma). This age combined with carbon isotopic data is then proposed to correspond to the U-Pb age of zircons(538.2±1.5Ma) from the Zhongyicun member of Meishucun Formation at Meishucun in eastern Yunna, thus, the E-C boundary in Gazngziping was placed between the Dengying formations and Liuchapo formatioms. therefore, the silica chimneys took place at the beginning of the Cambrian period. The temporal coincidence of silica chimneys and negative excursions of δ13C and δ34Spy pairs suggest hydrothermal activities were likely responsible for the isotopic changes. Under such a circumstance, vast amounts of greenhouse gases(CO2, CH4, H2S), with highly 13C-depleted carbon and 34S-depleted sulfur would be released into the ocean and atmosphere. A positive shift in δ34Scas and Δ34S values from the late Ediacaran to the Early Cambrian could be a reflection of enhanced bacterial sulfate reduction(BSR), strengthened by the intensified oceanic anoxia stimulated by hydrothermal activities. Based on the analyses of sedimentology and geochemistry, a model- “oceanic anoxia induced by hydrothermal–volcanic activies” was proposed to responsible for the formation of black chert-shales during this E-C transition. Under this case, hydrothermal-volcanic activies could release large large amount of greenhouse into atmosphere and metal micronutrients into the ocean, which may lead to global warming, stratified ocean, thereby a high palaeoproductivity; on the other hand, the massive releasing of reduced hydrothermal fluids with abundant H2S, could have in turn enhanced the ocean anoxia. All of these were favourable the for preservation of organic matter, and subsequent extensive deposition of black silica-shales.
Resumo:
Scientists have paid much attention to the greenhouse effects and the greenhouse gases for the fact of global warming. There are many uncertainties in the prediction of future climatic change. One of the important reasons causing the uncertainties is insufficient researches of the sources and sinks of greenhouse gases, especially, there is a missing sink in the global carbon cycle. The recent researches proposal that there may be an important carbon sink in the middle-latitude terrestrial ecosystems (vegetation and soil) in the North Hemisphere, despite that there is much disputation about its position and amplitude. Chinese loess is located in the middle latitude area in the North Hemisphere, what kind of role does it play in and how does it influence on the balance of the global greenhouse gases budget? For this reason, many samples were taken and analyzed from wide range and multi-stratum of Chinese loess to understand characteristics of major greenhouse gases in loess and loess possible effect on global greenhouse gas budget. Using self-made spiral corer, we totally took 81 gas samples and 65 soil samples from 7 loess profiles in China such as Zhaitang loess section of Beijing, Pianguan, Xingxian, Lishi, Puxian, Jishan loess section of Shanxi Province, and Luochuan loess section of Shaanxi Province. The gas concentrations for CO_2, CH_4 and N_2O, the contents of N_2, O_2 and carbonate, and the carbon isotopic compositions of CO_2 and carbonate in loess strata sequences are observed and measured. In addition, 19 gas samples data of the Weinan loess section, Shaanxi Province are combination with this research to study characteristics of greenhouse gases in loess. This research indicates that (1) the free gases in loess are neither paleo-atmospheric gases nor modern atmospheric gases; (2) the concentrations of CO_2, CH_4 and N_2O in loess are higher than atmospheric level; (3) the δ~(13)C of loess CO_2 shows that the CO_2 in loess mainly comes from the oxygenolysis of organic matters, but because of isotopic exchange with carbonate in loess, the carbon isotopic exchange with carbonate in loess, the carbon isotopic compositions of loess CO_2 are much more heavier than organic original CO_2; (4) the concentration of CH_4 in Malan loess is lower because it is not favorable for the decomposition of anaerobic bacteria in the Malan Loess; (5) estimation of the total amount of the carbonate in loess reveals that loess is a huge carbon reservoir (about 850PgC). In addition, the impact of the deuterogenic carbonatization during the loess accumulation on the global carbon cycle was discussed, and the preliminary conclusion is that the research work is still not enough to evaluate the effect of loess on the sources and sinks of the anthropogenic CO_2.
Resumo:
Carbon is an essential element for life, food and energy. It is also a key element in the greenhouse gases and therefore plays a vital role in climatic changes. The rapid increase in atmospheric concentration of CO_2 over the past 150 years, reaching current concentrations of about 370 ppmv, corresponds with combustion of fossii fuels since the beginning of the industrial age. Conversion of forested land to agricultural use has also redistributed carbon from plants and soils to the atmosphere. These human activities have significantly altered the global carbon cycle. Understanding the consequences of these activities in the coming decades is critical for formulating economic, energy, technology, trade, and security policies that will affect civilization for generations. Under the auspices of the International Geosphere-Biosphere Programme (IGBP), several large international scientific efforts are focused on elucidating the various aspects of the global carbon cycle of the past decade. It is only possible to balance the global carbon cycle for the 1990s if there is net carbon uptake by terrestrial ecosystems of around 2 Pg C/a. There are now some independent, direct evidences for the existence of such a sink. Policymarkers involved in the UN Framework Convention on Climate Change (UN-FCCC) are striving to reach consensuses on a 'safe path' for future emissions, the credible predictions on where and how long the terrestrial sink will either persist at its current level, or grow/decline in the future, are important to advice the policy process. The changes of terrestrial carbon storage depend not only on human activities, but also on biogeochemical and climatological processes and their interaction with the carbon cycles. In this thesis, the climate-induced changes and human-induced changes of carbon storage in China since the past 20,000 years are examined. Based on the data of the soil profiles investigated during China's Second National Soil Survey (1979-1989), the forest biomass measured during China's Fourth National Forest Resource Inventory (1989-1993), the grass biomass investigated during the First National Grassland Resource Survey (1980-1991), and the data collected from a collection of published literatures, the current terrestrial carbon storage in China is estimated to -144.1 Pg C, including -136.8 Pg C in soil and -7.3 Pg C in vegetation. The soil organic (SOC) and inorganic carbon (SIC) storage are -78.2 Pg C and -58.6 Pg C, respectively. In the vegetation reservoir, the forest carbon storage is -5.3 Pg C, and the other of-1.4 Pg C is in the grassland. Under the natural conditions, the SOC, SIC, forest and grassland carbon storage are -85.3 Pg C, -62.6 Pg C, -24.5 Pg C and -5.3 Pg C, respectively. Thus, -29.6 Pg C organic carbon has been lost due to land use with a decrease of -20.6%. At the same time, the SIC storage also has been decreased by -4.0 Pg C (-6.4%). These suggest that human activity has caused significant carbon loss in terrestrial carbon storage of China, especially in the forest ecosystem (-76% loss). Using the Paleocarbon Model (PCM) developed by Wu et al. in this paper, total terrestrial organic carbon storage in China in the Last Glacial Maximum (LGM) was -114.8 Pg C, including -23.1 Pg C in vegetation and -86.7 Pg C in soil. At the Middle Holocene (MH), the vegetation, soil and total carbon were -37.3 Pg C, -93.9 Pg C and -136.0 Pg C, respectively. This implies a gain of-21.2 Pg C in the terrestrial carbon storage from LGM to HM mainly due to the temperature increase. However, a loss of-14.4 Pg C of terrestrial organic carbon occurred in China under the current condition (before 1850) compared with the MH time, mainly due to the precipitation decrease associated with the weakening of the Asian summer monsoon. These results also suggest that the terrestrial ecosystem in China has a substantial potential in the restoration of carbon storage. This might be expected to provide an efficient way to mitigate the greenhouse warming through land management practices. Assuming that half of the carbon loss in the degraded terrestrial ecosystem in current forest and grass areas are restored during the next 50 years or so, the terrestrial ecosystem in China may sequestrate -12.0 Pg of organic carbon from the atmosphere, which represents a considerable offset to the industry's CO2 emission. If the ' Anthropocene' Era will be another climate optimum like MH due to the greenhouse effect, the sequestration would be increased again by -4.3 - 9.0 Pg C in China.
Resumo:
Tese de Doutoramento apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutror em Ciências da Terra.
Resumo:
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.
Resumo:
Workshop on Energy Greenhouse Gases & Environment, Porto, 2008
Resumo:
The case for energy policy modelling is strong in Ireland, where stringent EU climate targets are projected to be overshot by 2015. Policy targets aiming to deliver greenhouse gas and renewable energy targets have been made, but it is unclear what savings are to be achieved and from which sectors. Concurrently, the growth of personal mobility has caused an astonishing increase in CO2 emissions from private cars in Ireland, a 37% rise between 2000 and 2008, and while there have been improvements in the efficiency of car technology, there was no decrease in the energy intensity of the car fleet in the same period. This thesis increases the capacity for evidenced-based policymaking in Ireland by developing techno-economic transport energy models and using them to analyse historical trends and to project possible future scenarios. A central focus of this thesis is to understand the effect of the car fleet‘s evolving technical characteristics on energy demand. A car stock model is developed to analyse this question from three angles: Firstly, analysis of car registration and activity data between 2000 and 2008 examines the trends which brought about the surge in energy demand. Secondly, the car stock is modelled into the future and is used to populate a baseline “no new policy” scenario, looking at the impact of recent (2008-2011) policy and purchasing developments on projected energy demand and emissions. Thirdly, a range of technology efficiency, fuel switching and behavioural scenarios are developed up to 2025 in order to indicate the emissions abatement and renewable energy penetration potential from alternative policy packages. In particular, an ambitious car fleet electrification target for Ireland is examined. The car stock model‘s functionality is extended by linking it with other models: LEAP-Ireland, a bottom-up energy demand model for all energy sectors in the country; Irish TIMES, a linear optimisation energy system model; and COPERT, a pollution model. The methodology is also adapted to analyse trends in freight energy demand in a similar way. Finally, this thesis addresses the gap in the representation of travel behaviour in linear energy systems models. A novel methodology is developed and case studies for Ireland and California are presented using the TIMES model. Transport Energy
Resumo:
Due to growing concerns regarding the anthropogenic interference with the climate system, countries across the world are being challenged to develop effective strategies to mitigate climate change by reducing or preventing greenhouse gas (GHG) emissions. The European Union (EU) is committed to contribute to this challenge by setting a number of climate and energy targets for the years 2020, 2030 and 2050 and then agreeing effort sharing amongst Member States. This thesis focus on one Member State, Ireland, which faces specific challenges and is not on track to meet the targets agreed to date. Before this work commenced, there were no projections of energy demand or supply for Ireland beyond 2020. This thesis uses techno-economic energy modelling instruments to address this knowledge gap. It builds and compares robust, comprehensive policy scenarios, providing a means of assessing the implications of different future energy and emissions pathways for the Irish economy, Ireland’s energy mix and the environment. A central focus of this thesis is to explore the dynamics of the energy system moving towards a low carbon economy. This thesis develops an energy systems model (the Irish TIMES model) to assess the implications of a range of energy and climate policy targets and target years. The thesis also compares the results generated from the least cost scenarios with official projections and target pathways and provides useful metrics and indications to identify key drivers and to support both policy makers and stakeholder in identifying cost optimal strategies. The thesis also extends the functionality of energy system modelling by developing and applying new methodologies to provide additional insights with a focus on particular issues that emerge from the scenario analysis carried out. Firstly, the thesis develops a methodology for soft-linking an energy systems model (Irish TIMES) with a power systems model (PLEXOS) to improve the interpretation of the electricity sector results in the energy system model. The soft-linking enables higher temporal resolution and improved characterisation of power plants and power system operation Secondly, the thesis develops a methodology for the integration of agriculture and energy systems modelling to enable coherent economy wide climate mitigation scenario analysis. This provides a very useful starting point for considering the trade-offs between the energy system and agriculture in the context of a low carbon economy and for enabling analysis of land-use competition. Three specific time scale perspectives are examined in this thesis (2020, 2030, 2050), aligning with key policy target time horizons. The results indicate that Ireland’s short term mandatory emissions reduction target will not be achieved without a significant reassessment of renewable energy policy and that the current dominant policy focus on wind-generated electricity is misplaced. In the medium to long term, the results suggest that energy efficiency is the first cost effective measure to deliver emissions reduction; biomass and biofuels are likely to be the most significant fuel source for Ireland in the context of a low carbon future prompting the need for a detailed assessment of possible implications for sustainability and competition with the agri-food sectors; significant changes are required in infrastructure to deliver deep emissions reductions (to enable the electrification of heat and transport, to accommodate carbon capture and storage facilities (CCS) and for biofuels); competition between energy and agriculture for land-use will become a key issue. The purpose of this thesis is to increase the evidence-based underpinning energy and climate policy decisions in Ireland. The methodology is replicable in other Member States.
Resumo:
The European Union has set out an ambitious 20% target for renewable energy use by 2020. It is expected that this will be met mainly by wind energy. Looking towards 2050, reductions in greenhouse gas emissions of 80-95% are to be sought. Given the issues securing this target in the transport and agriculture sectors, it may only be possible to achieve this target if the power sector is carbon neutral well in advance of 2050. This has permitted the vast expansion of offshore renewables, wind, wave and tidal energy. Offshore wind has undergone rapid development in recent years however faces significant challenges up to 2020 to ensure commercial viability without the need for government subsidies. Wave energy is still in the very early stages of development so as yet there has been no commercial roll out. As both of these technologies are to face similar challenges in ensuring they are a viable alternative power generation method to fossil fuels, capitalising on the synergies is potentially a significant cost saving initiative. The advent of hybrid solutions in a variety of configurations is the subject of this thesis. A singular wind-wave energy platform embodies all the attributes of a hybrid system, including sharing space, transmission infrastructure, O&M activities and a platform/foundation. This configuration is the subject of this thesis, and it is found that an OWC Array platform with multi-MegaWatt wind turbines is a technically feasible, and potentially an economically feasible solution in the long term. Methods of design and analysis adopted in this thesis include numerical and physical modelling of power performance, structural analysis, fabrication cost modelling, simplified project economic modelling and time domain reliability modelling of a 210MW hybrid farm. The application of these design and analysis methods has resulted in a hybrid solution capable of producing energy at a cost between €0.22/kWh and €0.31/kWh depending on the source of funding for the project. Further optimisation through detailed design is expected to lower this further. This thesis develops new and existing methods of design and analysis of wind and wave energy devices. This streamlines the process of early stage development, while adhering to the widely adopted Concept Development Protocol, to develop a technically and economically feasible, combined wind-wave energy hybrid solution.
Resumo:
The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diameter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently leading to a radiative forcing which is estimated to be about -0.8 watt per m2 by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and smaller droplets and these clouds have a higher albedo and are more stable compared to clouds with larger droplets. Not only sulfate, but also nitrate and polar organic compounds, formed as intermediates in degradation processes, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m-2 and an indirect effect of as large as -5 watt m-2. About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large radiative forcing is obviously non-uniform and depends on local conditions.
Resumo:
Carbon sequestration in sandstone saline reservoirs holds great potential for mitigating climate change, but its storage potential and cost per ton of avoided CO2 emissions are uncertain. We develop a general model to determine the maximum theoretical constraints on both storage potential and injection rate and use it to characterize the economic viability of geosequestration in sandstone saline aquifers. When applied to a representative set of aquifer characteristics, the model yields results that compare favorably with pilot projects currently underway. Over a range of reservoir properties, maximum effective storage peaks at an optimal depth of 1600 m, at which point 0.18-0.31 metric tons can be stored per cubic meter of bulk volume of reservoir. Maximum modeled injection rates predict minima for storage costs in a typical basin in the range of $2-7/ ton CO2 (2005 U.S.$) depending on depth and basin characteristics in our base-case scenario. Because the properties of natural reservoirs in the United States vary substantially, storage costs could in some cases be lower or higher by orders of magnitude. We conclude that available geosequestration capacity exhibits a wide range of technological and economic attractiveness. Like traditional projects in the extractive industries, geosequestration capacity should be exploited starting with the low-cost storage options first then moving gradually up the supply curve.
Resumo:
This study assesses the value of restoring forested wetlands via the U.S. government's Wetlands Reserve Program (WRP) in the Mississippi Alluvial Valley by quantifying and monetizing ecosystem services. The three focal services are greenhouse gas (GHG) mitigation, nitrogen mitigation, and waterfowl recreation. Site- and region-level measurements of these ecosystem services are combined with process models to quantify their production on agricultural land, which serves as the baseline, and on restored wetlands. We adjust and transform these measures into per-hectare, valuation-ready units and monetize them with prices from emerging ecosystem markets and the environmental economics literature. By valuing three of the many ecosystem services produced, we generate lower bound estimates for the total ecosystem value of the wetlands restoration. Social welfare value is found to be between $1435 and $1486/ha/year, with GHG mitigation valued in the range of $171 to $222, nitrogen mitigation at $1248, and waterfowl recreation at $16. Limited to existing markets, the estimate for annual market value is merely $70/ha, but when fully accounting for potential markets, this estimate rises to $1035/ha. The estimated social value surpasses the public expenditure or social cost of wetlands restoration in only 1 year, indicating that the return on public investment is very attractive for the WRP. Moreover, the potential market value is substantially greater than landowner opportunity costs, showing that payments to private landowners to restore wetlands could also be profitable for individual landowners. © 2009 Elsevier B.V.
Resumo:
Gemstone Team Renewables