795 resultados para biogas, biometano, upgrading, purificazione


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fuel cells are electrochemical energy conversion devices that convert fuel and oxidant electrochemically into electrical energy, water and heat. Compared to traditional electricity generation technologies that use combustion processes to convert fuel into heat, and then into mechanical energy, fuel cells convert the hydrogen and oxygen chemical energy into electrical energy, without intermediate conversion processes, and with higher efficiency. In order to make the fuel cells an achievable and useful technology, it is firstly necessary to develop an economic and efficient way for hydrogen production. Molecular hydrogen is always found combined with other chemical compounds in nature, so it must be isolated. In this paper, the technical, economical and ecological aspects of hydrogen production by biogas steam reforming are presented. The economic feasibility calculation was performed to evaluate how interesting the process is by analyzing the investment, operation and maintenance costs of the biogas steam reformer and the hydrogen production cost achieved the value of 0.27 US$/kWh with a payback period of 8 years. An ecological efficiency of 94.95%, which is a good ecological value, was obtained. The results obtained by these analyses showed that this type of hydrogen production is an environmentally attractive route. © 2013 Elsevier Ltd.

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Versión en inglés disponible en Biblioteca

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In the 1980s Butler adapted the life cycle product model to the tourism industry and created the “Tourism Area Life Cycle (TALC) model”. The model recognizes six stages in the tourism product life cycle: exploration, investment, development, consolidation, stagnation and followed, after stagnation, by decline or revitalization of the product. These six stages can in turn be regrouped into four main stages. The Butler model has been applied to more than 30 country cases with a wide degree of success. De Albuquerque and Mc Elroy (1992) applied the TALC model to 23 small Caribbean island States in the 1990s. Following De Albuquerque and Mc Elroy, the TALC is applied to the 32 member countries of the Caribbean Tourism Organization (CTO) (except for Cancun and Cozumel) to locate their positions along their tourism life-cycle in 2007. This is done using the following indicators: the evolution of the level, market share and growth rate of stay-over arrivals; the growth rate and market share of visitor expenditures per arrival and the tourism styles of the destinations, differentiating between ongoing mass tourism and niche marketing strategies and among upscale, mid-scale and low-scale destinations. Countries have pursued three broad classes of strategies over the last 15 years in order to move upward in their tourism life cycle and enhance their tourism competitiveness. There is first a strategy that continues to rely on mass-tourism to build on the comparative advantages of “sun, sand and sea”, scale economies, all-inclusive packages and large amounts of investment to move along in Stage 2 or Stage 3 (Cuba, Dominican Republic, Puerto Rico). There is a second strategy pursued mainly by very small islands that relies on developing specific niche markets to maintain tourism competitiveness through upgrading (Anguilla, Antigua and Barbuda, British Virgin Islands and Turks and Caicos), allowing them to move from Stage 2 to Stage 3 or Stage 3 to a rejuvenation stage. There is a third strategy that uses a mix of mass-tourism, niche marketing and quality upgrading either to emerge onto the intermediate stage (Trinidad and Tobago); avoid decline (Aruba, The Bahamas) or rejuvenate (Barbados, Jamaica and the United States Virgin Islands). There have been many success stories in Caribbean tourism competitiveness and further research should aim at empirically testing the determinants of tourism competitiveness for the region as a whole.

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The main purpose of this paper is to explore and analyze the contributions that publicprivate partnerships and public policy have made in the development of tourism in the Caribbean as tools for enhancing competitiveness in the Caribbean tourism industry. The paper explores these contributions mainly in the context of the upgrading strategies that Caribbean countries have pursued over the past 15 years or so and using the lens of the tourism value chain and tourism cluster approach. The paper also analyzes the potential roles that public-private partnerships and public policy will continue to play in the future especially in the process of building linkages between the tourism sector and other sectors in order to increase net benefits from tourism to the Region. This paper is divided into five sections. In Section I, we define public-private partnerships (PPP) and describe the areas in tourism where PPP are most widely used, the tools used to implement PPP in tourism and the various forms of PPP. Economic arguments are then laid to motivate PPP as a determinant of tourism competitiveness using the tourism value-chain and tourism cluster approach. Specific case examples illustrating the contributions of PPP and public policy towards increasing tourism competitiveness are provided at a regional level and for specific areas in Sections II and III respectively. Section IV summarizes findings from the previous two sections and discusses ways to enhance the effectiveness of PPP and public policy in Caribbean tourism for increased competitiveness. Section V analyzes a few of the challenges that the Caribbean tourism sector is facing. The final section proposes new areas of intervention for PPP and public policy as tools for enhancing competitiveness in the Caribbean tourism sector in order to assist the region in addressing these challenges.

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The main purpose of this paper is to explore and analyze the contributions that publicprivate partnerships and public policy have made in the development of tourism in the Caribbean as tools for enhancing competitiveness in the Caribbean tourism industry. The paper explores these contributions mainly in the context of the upgrading strategies that Caribbean countries have pursued over the past 15 years or so and using the lens of the tourism value chain and tourism cluster approach. The paper also analyzes the potential roles that public-private partnerships and public policy will continue to play in the future especially in the process of building linkages between the tourism sector and other sectors in order to increase net benefits from tourism to the Region. This paper is divided into five sections. In Section I, we define public-private partnerships (PPP) and describe the areas in tourism where PPP are most widely used, the tools used to implement PPP in tourism and the various forms of PPP. Economic arguments are then laid to motivate PPP as a determinant of tourism competitiveness using the tourism value-chain and tourism cluster approach. Specific case examples illustrating the contributions of PPP and public policy towards increasing tourism competitiveness are provided at a regional level and for specific areas in Sections II and III respectively. Section IV summarizes findings from the previous two sections and discusses ways to enhance the effectiveness of PPP and public policy in Caribbean tourism for increased competitiveness. Section V analyzes a few of the challenges that the Caribbean tourism sector is facing. The final section proposes new areas of intervention for PPP and public policy as tools for enhancing competitiveness in the Caribbean tourism sector in order to assist the region in addressing these challenges.

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This paper reviews and synthesizes the literature on social upgrading, while exploring its connections with economic upgrading. Using the parsimonious method proposed by Bernhardt and Milberg and an alternative method that takes into account increases in national productivity, this paper analyzes the case of Mexico. Though the proposed approach to social upgrading can be made more sophisticated through the inclusion of more variables, in order to facilitate the replication of the analysis in developing countries where data are scarce, labor productivity, wages and employment were considered sufficient information to analyze economic and social upgrading.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Cogeneration may be defined as the simultaneous production of electric power and useful heat from the burning of a single fuel. This technique of combined heat and power production has been applied in both the industrial and tertiary sectors. It has been mainly used because of its overall efficiency, and the guarantee of electricity with a low level of environmental impact. The compact cogeneration systems using internal combustion engine as prime movers are thoroughly applied because of the good relationship among cost and benefit obtained in such devices. The cogeneration system of this study consists of an internal combustion engine using natural gas or biogas as fuel, combined with two heat exchangers and an absorption chiller utilising water-ammonia as working mixture. This work presents an energetic and economic comparison between natural gas and biogas as fuel used for the system proposed. The results are useful to identify the feasible applications for this system, such as residential sector in isolated areas, hotels, universities etc. (C) 2014 Elsevier Ltd. All rights reserved.

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The biogas originated from anaerobic degradation of organic matter in landfills consists basically in CH4, CO2, and H2O. The landfills represent an important depository of organic matter with high energetic potential in Brazil, although with inexpressive use in the present. The estimation of production of the productive rate of biogas represents one of the major difficulties of technical order to the planning of capture system for rational consumption of this resource. The applied geophysics consists in a set of methods and techniques with wide use in environmental and hydrogeological studies. The DC resistivity method is largely applied in environmental diagnosis of the contamination in soil and groundwater, due to the contrast of electrical properties frequent between contaminated areas and the natural environment. This paper aims to evaluate eventual relationships between biogas flows quantified in drains located in the landfill, with characteristic patterns of electrical resistivity in depth. The drain of higher flow (117 m3 /h) in depth was characterized for values between 8000 Ω⋅m and 100.000 Ω⋅m, in contrast with values below 2000 Ω⋅m, which characterize in subsurface the drain with less flow (37 m3 /h), besides intermediary flow and electrical resistivity values, attributed to the predominance of areas with accumulation or generation of biogas.

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The need for increasing the loading capacity of transmission lines in a traditional way, by replacing or reinforcement of the structures and foundations on routes crossing areas considered of permanent environmental preservation, may require additional works that alter the environment. The present rigorous environmental legislation turns these changes and substitution unfeasible. One way to increase the capacity of these lines is the use of new conductor technology. The aim of this paper is to discuss the needs for upgrading a transmission line and minimize or eliminate the damage to the environment by using special conductors. Because the aluminum conductor composite reinforced technology is relatively new and considering the lack of information related to its effective performance in practical system, there is a need to verify the behavior of these conductors through monitoring procedures.

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Ni catalysts supported on gamma-Al2O3 modified by Rh and La were prepared and evaluated on the reforming of a model biogas. The catalysts were characterized by EDS, XRD, TPR, XANES and surface area estimation (BET). The results showed that in the original Ni catalyst, the Ni interacted strongly with the alumina support, exhibiting high reduction temperatures in TPR tests. In the catalytic tests, the addition of Rh on Ni catalysts improved CH4 conversion but also increased carbon deposition, possible by causing the segregation of Ni species under the reaction conditions. The presence of La on Ni catalysts reduced the carbon deposition by favoring the gasification of carbon species. Addition of synthetic air to the process improved the CH4 conversion and also decreased the carbon formation. The catalysts Ni, Rh-NiLa, and Rh showed good results in the conversion of model sulfur-free biogas, which suggests that they are promising catalysts to be tested in conversion of real biogas. (C) 2012 Elsevier B.V. All rights reserved.