983 resultados para RENEWABLE RESOURCES


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Tese de Doutoramento - Programa Doutoral em Engenharia Industrial e Sistemas (PDEIS)

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Plants produce a range of biopolymers for purposes such as maintenance of structural integrity, carbon storage, and defense against pathogens and desiccation. Several of these natural polymers are used by humans as food and materials, and increasingly as an energy carrier. In this review, we focus on plant biopolymers that are used as materials in bulk applications, such as plastics and elastomers, in the context of depleting resources and climate change, and consider technical and scientific bottlenecks in the production of novel or improved materials in transgenic or alternative crop plants. The biopolymers discussed are natural rubber and several polymers that are not naturally produced in plants, such as polyhydroxyalkanoates, fibrous proteins and poly-amino acids. In addition, monomers or precursors for the chemical synthesis of biopolymers, such as 4-hydroxybenzoate, itaconic acid, fructose and sorbitol, are discussed briefly

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The performance of natural extracts obtained from underutilized and residual vegetal and macroalgal biomass processed with food-grade green solvents was compared with that of commercial antioxidants. Selected extracts were obtained from two terrestrial sources: winery byproducts concentrate (WBC) and chestnut burs hydrothermally fractionated extract (CBAE), and from two underutilized seaweeds: Sargassum muticum extracts, either extracted with ethanol (SmEE) or after alginate extraction and hydrothermal fractionation (SmAE) and from Ulva lactuca processed by mild acid extraction and membrane concentration (UlAE). These extracts showed in vitro antioxidant properties comparable to commercial antioxidants and were safe for topical use based on the absence of skin-irritant effects at 0.1% on reconstructed human tissues. The stability of several cosmetic model emulsions was assessed during accelerated oxidation assays. The incorporation of natural extracts produced from renewable underutilized resources at 0.4-0.5% in an oil-in-water emulsions reduced lipid oxidation during storage.

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Introduction of second-generation biofuels is an essential factor for meeting the EU’s 2020 targets for renewable energy in the transport sector and enabling the more ambitious targets for 2030. Finland’s forest industry is strongly involved in the development and commercialising of second-generation biofuel production technologies. The goal of this paper is to provide a quantified insight into Finnish prospects for reaching the 2020 national renewable energy targets and concurrently becoming a large-scale producer of forest biomass based second-generation biofuels feeding the increasing demand in European markets. The focus of the paper is on assessing the potential for utilising forest biomass for liquid biofuels up to 2020. In addition, technological issues related to the production of second-generation biofuels were reviewed. Finland has good opportunities to realise a scenario to meet 2020 renewable energy targets and for large-scale production of wood based biofuels. In 2020, biofuel production from domestic forest biomass in Finland may reach nearly a million ton (40 PJ). With the existing biofuel production capacity (20 PJ/yr) and national biofuel consumption target (25 PJ) taken into account, the potential net export of biofuels from Finland in 2020 would be 35 PJ, corresponding to 2–3% of European demand. Commercialisation of second-generation biofuel production technologies, high utilisation of the sustainable harvesting potential of Finnish forest biomass, and allocation of a significant proportion of the pulpwood harvesting potential for energy purposes are prerequisites for this scenario. Large-scale import of raw biomass would enable remarkably greater biofuel production than is described in this paper.

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The threat of global warming and its consequences are widely recognized, and the question of how to proceed with the long transition towards fossil fuel -neutral economies concerns many nations and people. At the same time the world’s primary energy use is predicted to increase significantly during the next decades as a result of global population and welfare increase. Improved energy efficiency and increased use of renewable energy sources in the world’s energy mix play important roles in the future energy production and consumption. The objective of this thesis is to study how novel renewable energy technologies, such as distributed small-scale bio-fueled combined heat and power production and wind power technologies could be commercialized efficiently. A wide array of attributes may contribute to the diffusion of new products. In general, the bioenergy and wind power technologies are in emerging phases, and the diffusion stage varies from country to country. The effects of firms’ technology choices, collaboration and alliances are studied in this thesis. Furthermore, the roles of national energy infrastructure and energy support schemes in the commercialization of new renewable energy products are explored. The empirical data is based on energy expert interviews, financial and patent data, and literature reviews of different case studies. The thesis comprises two parts. The first part provides an overview of the study, and the second part includes six research publications. The results reveal that small-scale bio-fueled combined heat and power production and wind power technologies are still in emerging phases in their life cycles, and energy support schemes are crucial in the market diffusion. The study contributes to earlier findings in the literature and industry by confirming that adequate energy policies and energy infrastructure are fundamental in the commercialization of novel renewable energy technologies. Firm-specific issues, including business relationships and new business models, and market-related issues will have a more significant role in the market penetration in the future, when the technologies mature and become competitive without political support schemes.

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Le Traité de Marrakech stipule que le commerce et le développement économique devraient être orientés de manière à permettre l’utilisation optimale des ressources mondiales, conformément à l’objectif de développement durable. Combiné aux dispositions du Protocole de Kyoto et du Traité de Copenhague, les gouvernements poursuivent de politiques nationales favorisant les producteurs nationaux au détriment des étrangers. Cette mémoire propose une analyse des règles de l’OMC, dans le but de déterminer les mesures disciplinaires possibles contre le Canada à l'égard de ses mécanismes de support de l’énergie renouvelable. Une analyse des règles énoncées dans le GATT, l’Accord sur les subventions et les mesures compensatoires et divers accords multilatéraux conclus dans le cadre de l’OMC permet de déterminer si elles pourraient s’appliquer aux mécanismes de support de l’énergie renouvelable. Une analyse des programmes du Québec et de l’Ontario permet une prise de position quant à leur conformité aux règles commerciales de l’OMC.

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This paper presents a new methodology for the operation and control of a single-phase current-source (CS) Boost Inverter, considering that the conventional CS boost inverter has a right-half-plane (RHP) zero in its control-to-output transfer function, and this RHP zero causes the known non-minimum-phase effects. In this context, a special design with low boost inductance and a multi-loop control is developed in order to assure stable and very fast dynamics. Furthermore, the proposed inverter presents output voltage with very low total harmonic distortion (THD), reduced components and high power density. Therefore, this paper presents the inverter operation, the proposed control technique, the main simulation results and a prototype in order to demonstrate the feasibility of the proposal. © 2011 IEEE.

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Biofuels and their blends with fossil fuel are important energy resources, whose production and application have been largely increased internationally. This study focuses on the evaluation of the activation energy of the thermal decomposition of three pure fuels: farnesane (renewable diesel from sugar cane), biodiesel and fossil diesel and their blends (20% farnesene and 80% of fossil diesel - 20F80D and 20% farnesane, 50% fossil diesel and 30% biodiesel - 20F50D30B). Activation energy has been determined from thermogravimetry and Model-Free Kinetics. Results showed that not only the cetane number is important to understand the behavior of the fuels regarding ignition delay, but also the profile of the activation energy versus conversion curves shows that the chemical reactions are responsible for the performance at the beginning of the process. In addition, activation energy seemed to be suitable in describing reactivity in the case of blends of renewable and fossil fuels. © 2013 Elsevier B.V.

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Belize is currently faced with several critical challenges associated with the production, distribution and use of energy. Despite an abundance of renewable energy resources, the country remains disproportionately dependent on imported fossil fuels, which exposes it to volatile and rising oil prices, limits economic development, and retards its ability to make the investments that are necessary for adapting to climate change, which pose a particularly acute threat to the small island states and low-lying coastal nations of the Caribbean. This transition from energy consumption and supply patterns that are based on imported fossil fuels and electricity towards a more sustainable energy economy that is based on environmentally benign, indigenous renewable energy technologies and more efficient use of energy requires concerted action as the country is already challenged by limited fiscal space which reduces its ability to provide some fiscal incentives, which have been proven to be effective tools for the promotion of sustainable energy markets in a number of countries. This report identifies the fiscal and regulatory barriers to implementation of energy efficiency measures and renewable energy technologies in Belize. Data and information were derived from stakeholder consultations conducted within the country. The major result of the assessment is that the transition of policies and plans into tangible action needs to be increased. In this regard, it is necessary to articulate sub-policies of the National Energy Policy to amend the Public Utilities Commission Act, to develop a grid interconnection policy, to establish minimum energy performance standards for buildings and equipment and to develop a public procurement policy. Finally, decisions on renewable energy and energy efficiency-related incentives from the Government formally requires decision-makers to solve what may be extremely complex optimization problems in order to obtain the lowest-cost provision of energy services to society, thereby weighing the cost of revenue losses with the benefits of fuel and infrastructure expansion savings. The establishment of a management system that is efficient, flexible, and transparent, which will facilitate the implementation of the strategic objectives and outputs in the time available, with the financial resources allocated is recommended. Support is required for additional institutional and capacity strengthening.

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Biofuels and their blends with fossil fuel are important energy resources, which production and application have been largely increased internationally. This study focus on the development of a correlation between apparent activation energy (Ea) and NOx emission of the thermal decomposition of three pure fuels: farnasane (renewable diesel from sugar cane), biodiesel and fossil diesel and their blends. Apparent Activation energy was determined by using thermogravimetry and Model-Free Kinetics. NOx emission was obtained from the European Stationary Cycle (ESC) with OM 926LA CONAMA P7/Euro 5 engine. Results showed that there is a linear correlation between apparent activation energy and NOx emission with R2 of 0,9667 considering pure fuels and their blends which is given as: NOx = 2,2514Ea - 96,309. The average absolute error of this correlation is 2.96% with respect to the measured NOx value. The main advantage of this correlation is its capability to predict NOx emission when either a new pure fuel or a blend of fuels is proposed to use in enginees.

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The future economic development trajectory for India is likely to result in rapid and accelerated growth in energy demand, with expected shortages. Many of its current policies and strategies are aimed at the improvement and possible maximization of energy production from the renewable sector. It is also clear that while energy-conservation and energy-efficiency can make an important contribution in the national energy strategy, renewable energies will be essential to the solution and are likely to play an increasingly important role for the growth of grid power, providing energy access, reducing consumption of fossil fuels, and helping India pursue its low carbon progressive pathway. However, most of the states in India, like the northernmost State of Jammu and Kashmir (J&K), have experienced an energy crisis over a sustained period of time. As India intends to be one of the emerging powers of the 21st century, it has to embark upon with these pressing issues in a more sustainable manner and accordingly initiate various renewable energy projects within these states. This paper will provide a broad-spectrum view about the energy situation within J&K and will highlight the current policies along with future strategies for the optimal utilization of renewable energy resources.

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The future economic growth for India is likely to result in rapid and accelerated surge in energy demand, with expected shortages in terms of supply. Many of its current policies and strategies are aimed at the improvement and possible maximization of energy production from the renewable sector. It is also clear that while energy conservation and energy efficiency can make an important contribution, renewable energies will be essential to the solution and are likely to play an increasingly important role for providing enhanced energy access, reducing consumption of fossil fuels, and helping India pursue its low-carbon progressive pathway. However, most of the states in India, like the northernmost state of Jammu and Kashmir, have experienced an energy crisis over a sustained period of time and the government both at center and state level has to embark upon with these pressing issues in a more sustainable manner and accordingly initiate various renewable energy projects within these states. This paper will provide a broad-spectrum view about the energy situation within Jammu and Kashmir and will highlight the current policies along with future strategies for the optimal utilization of renewable energy resources.

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The European energy sector is undergoing a major transformation and is facing a series of difficult challenges. These include a high and increasing dependence on external energy resources; dramatically reduce the need for the emissions of greenhouse gases to meet environmental objectives and the difficulties related to the promotion of energy market effectively integrated and competitive. Some of the policies associated with the various objectives are sometimes in conflict with each other, while in other cases are mutually reinforcing.The aim of this paper is to do a scienti?c analysis of the developments so far and the expectations for the coming period focusing on the pillars of energy policy in the EU in terms of security of supply, environment, climate change and promoting a competitive and integrated market. The use of renewable energy sources is seen as a key element of European energy policy and should help to: reduce dependence on fuel from non-member countries; reduce emissions from carbon-based energy sources, and; decouple energy costs from oil prices.

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The recognition of the relevance of energy, especially of the renewable energies generated by the sun, water, wind, tides, modern biomass or thermal is growing significantly in the global society based on the possibility it has to improve societies′ quality of life, to support poverty reduction and sustainable development. Renewable energy, and mainly the energy generated by large hydropower generation projects that supply most of the renewable energy consumed by developing countries, requires many technical, legal, financial and social complex processes sustained by innovations and valuable knowledge. Besides these efforts, renewable energy requires a solid infrastructure to generate and distribute the energy resources needed to solve the basic needs of society. This demands a proper construction performance to deliver the energy projects planned according to specifications and respecting environmental and social concerns, which implies the observance of sustainable construction guidelines. But construction projects are complex and demanding and frequently face time and cost overruns that may cause negative impacts on the initial planning and thus on society. The renewable energy issue and the large renewable energy power generation and distribution projects are particularly significant for developing countries and for Latin America in particular, as this region concentrates an important hydropower potential and installed capacity. Using as references the performance of Venezuelan large hydropower generation projects and the Guri dam construction, this research evaluates the tight relationship existing between sustainable construction and knowledge management and their impact to achieve sustainability goals. The knowledge management processes are proposed as a basic strategy to allow learning from successes and failures obtained in previous projects and transform the enhancement opportunites into actions to improve the performance of the renewable energy power generation and distribution projects.