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02648 Exergy analysis of a pulp and paper mill
07 Alternative energy sources (others, including development, economics) 05/02646 Design and performance analysis of impulse turbine for a wave energy power plant Thakker, A. et al. International Journal of Energy Research, 2005, 29, (1), 13 36. Wave energy is the most abundant source of renewable energy in the world. For the last two decades, engineers have been investigating and defining different methods for power extraction from wave motion. Two different turbines, namely Wells turbine and impulse turbine with guide vanes, are most commonly used around the world for wave energy power generation. The ultimate goal is to optimize the performance of the turbine under actual sea conditions. The total research effort has several strands; there is the manufacture and experimental testing of new turbines using the Wave Energy Research Team's (WERT) 0.6 m turbine test rig, the theoretical and computational analysis of the present impulse turbine using a commercial software package and finally the prediction of the performance of the turbine in a representative wave power device under real sea conditions using numerical simulation. Also, the W E R T 0.6 m turbine test rig was upgraded with a data acquisition and control system to test the turbine in the laboratory under real sea conditions using the computer control system. As a result, it is proven experimentally and numerically that the turbine efficiency has been raised by 7% by reducing the hub-to-tip ratio from 0.7 to 0.6. Effect of tip clearance on performance of the turbine has been studied numerically and designed tip clearance ratio of 1% has been validated. From the numerical simulation studies, it is computed that the mean conversion efficiency is reduced around 5% and 4.58% due to compressible flow and damping effects inside o w e device.
05/02647 Electricity generation: regulatory mechanisms to incentive renewable alternative energy sources in Brazil Cavaliero, C. K. N. and Da Silva, E. P. Energy Policy, 2005, 33, (13), 1745-1752. The dissemination of renewable alternative energy sources for electricity generation has always being done through regulatory mechanisms, created and managed by the government of each country. Since these sources are more costly to generate, they have received incentives in response to worldwide environmental concerns, above all with regard to the reduction of CO2 emissions. In Brazil, the electricity generation from renewable alternative sources is experiencing a new phase of growth. Until a short time ago, environmental appeal was the strongest incentive to these sources in Brazil but it was insufficient to attain its objective. With the electricity crisis and the rationing imposed in 2001, another important factor gained awareness: the need to diversify energy sources. Within this context, this work has the objective of analysing the regulatory mechanisms recently developed to stimulate electricity generation from renewable alternative energy sources in Brazil by following the experience of other countries such as the United States, United Kingdom and Germany.
05•02648
Exergy analysis of a pulp and paper mill
Gong, M. International Journal of Energy Research, 2005, 29, (I), 79 93. Different energy and exergy concepts and methods are presented and applied to a Swedish pulp and paper mill. Flow diagrams show that the exergy content is mostly much less than the energy content of the flows. The largest exergy losses appear in the boilers. Heating processes are highly exergy inefficient. A limited life cycle exergy analysis shows that the exergy output amounts to over three times the spent exergy as nonsustainable resources. By replacing the present use of non-sustainable resources, mostly fuel oil, the mill could move towards a truly sustainable process.
05•02649 Exploring the possibilities for setting up sustainable energy systems for the long term: two visions for the Dutch energy system in 205 Treffers, D. J. et al. Energy Policy, 2005, 33, (13), 1723-1743. In this paper, two long-term visions of the Dutch future energy system are composed, analysed and evaluated. Both visions were set up to meet the requirement to reduce the greenhouse gas (GHG) emissions with 80% in 2050 in comparison to 1990. The two visions start from very different perspectives and contexts. Quantitative analysis shows that when economic growth and energy use follow a business as usual development, emissions of GHGs can increase up to 250% of 1990 levels. The two, rather opposing, visions show that it is feasible to combine (strong) economic growth with far going reduction of G H G emissions, provided a number of key options are developed and applied. These options were chosen and discussed during several meetings by stakeholders in a dialogue process, using feedback from scientists, and consist of improvements in energy efficiency in industry, CO2 neutral feedstocks for transportation, renewable energy and highly insulated buildings in the built environment and improvements in the primary production of the agricultural sector. It is clear that drastic changes in many areas in society are required to obtain the desired GHG-emission levels in 2050. The results also show though, that such a
development can be realized in different ways. In other words, there are various ways to implement a low G H G emission economy in the long term.
05•02650 Hierarchically structured exergetic and exergoeconomic analysis and evaluation of energy conversion processes Hebecker, D. et al. Energy Conversion and Management, 2005, 46, (7 8), 1247-1266. Evaluation of the efficiency and economic benefit of energy conversion processes and technologies requires a scientifically based analysis. The hierarchically structured exergetic analysis provides a detailed characterization of complex technical systems. By defining corresponding evaluation coefficients, the exergetic efficiency can be assessed for units within the whole system. Based on this exergetic analysis, a thermo-economic evaluation method is developed. A cost function is defined for all units, subsystems and the total plant, so that the cost flow in the system can be calculated. Three dimensionless coefficients, the Pauer factor, the loss coefficient and the cost factor, enable pinpointing cost intensive process units, allocating cost in cases of coproduction and gaining insight for future design improvements. The methodology is demonstrated by a biomass gasification plant producing electricity, heat and cold.
05/02651 Managing a reservoir-based hydro-energy plant: building understanding in the buy and sell decisions in a changing environment van Ackere, A. et al. Energy Policy, 2005, 33, (7), 939-947. This paper describes a modelling process at a Norwegian chemical producer, who owns 20% of a reservoir based hydro-energy plant. While the initial objective was to increase the profitability of the energy plant (in particular by an improved understanding of buying and selling decisions and a reconciliation of the managerial and engineering points of view in the context of a liberalized energy market) the process resulted in the company's decision to refocus on its core-business. The process illustrates how a modelling process can lead to a fundamental reframing of the issue, resulting in major change for the company.
05•02652 Multi-criteria analysis of alternative-fuel buses for public transportation Tzeng, G.-S. et al. Energy Policy, 2005, 33, (11), 1373 1383. The technological development of buses with new alternative fuels is considered in this paper. Several types of fuels are considered as alternative-fuel modes, i.e. electricity, fuel cell (hydrogen), and methanol. Electric vehicles may be considered the alternative-fuel vehicles with the lowest air pollution. Hybrid electric vehicles provide an alternate mode, at least for the period of improving the technology of electric vehicles. A hybrid electric vehicle is defined as a vehicle with the conventional internal combustion engine and an electric motor as its major sources of power. Experts from different decision-making groups performed the multiple attribute evaluation of alternative vehicles. AHP is applied to determine the relative weights of evaluation criteria. TOPSIS and VIKOR are compared and applied to determine the best compromise alternative fuel mode. The result shows that the hybrid electric bus is the most suitable substitute bus for Taiwan urban areas in the short and median term. But, if the cruising distance of the electric bus extends to an acceptable range, the pure electric bus could be the best alternative.
05/02653 PEM electrolysis for production of hydrogen from renewable energy sources Barbir, F. Solar Energy, 2005, 78, (5), 661 669. PEM electrolysis is a viable alternative for generation of hydrogen from renewable energy sources. Several possible applications are discussed, including grid independent and grid assisted hydrogen generation, use of an electrolyser for peak shaving, and integrated systems both grid connected and grid independent where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed. Specific issues regarding the use of PEM electrolyser in the renewable energy systems are addressed, such as sizing of electrolyser, intermittent operation, output pressure, oxygen generation, water consumption and efficiency.
05•02654 Potential applications of renewable energy sources, biomass combustion problems in boiler power systems and combustion related environmental issues Demirbas, A. Progress in Energy and Combustion Science, 2005, 3 l, (2), 171 192. This paper describes the potential applications of renewable energy sources to replace fossil fuel combustion as the prime energy sources in various countries, and discusses problems associated with biomass combustion in boiler power systems. Here, the term biomass includes organic matter produced as a result of photosynthesis as well as municipal, industrial and animal waste material. Brief summaries of the basic concepts involved in the combustion of biomass fuels are
Fuel and Energy Abstracts
November 2005 387
05/02647 Electricity generation: regulatory mechanisms to incentive renewable alternative energy sources in Brazil Cavaliero, C. K. N. and Da Silva, E. P. Energy Policy, 2005, 33, (13), 1745-1752. The dissemination of renewable alternative energy sources for electricity generation has always being done through regulatory mechanisms, created and managed by the government of each country. Since these sources are more costly to generate, they have received incentives in response to worldwide environmental concerns, above all with regard to the reduction of CO2 emissions. In Brazil, the electricity generation from renewable alternative sources is experiencing a new phase of growth. Until a short time ago, environmental appeal was the strongest incentive to these sources in Brazil but it was insufficient to attain its objective. With the electricity crisis and the rationing imposed in 2001, another important factor gained awareness: the need to diversify energy sources. Within this context, this work has the objective of analysing the regulatory mechanisms recently developed to stimulate electricity generation from renewable alternative energy sources in Brazil by following the experience of other countries such as the United States, United Kingdom and Germany.
05•02648
Exergy analysis of a pulp and paper mill
Gong, M. International Journal of Energy Research, 2005, 29, (I), 79 93. Different energy and exergy concepts and methods are presented and applied to a Swedish pulp and paper mill. Flow diagrams show that the exergy content is mostly much less than the energy content of the flows. The largest exergy losses appear in the boilers. Heating processes are highly exergy inefficient. A limited life cycle exergy analysis shows that the exergy output amounts to over three times the spent exergy as nonsustainable resources. By replacing the present use of non-sustainable resources, mostly fuel oil, the mill could move towards a truly sustainable process.
05•02649 Exploring the possibilities for setting up sustainable energy systems for the long term: two visions for the Dutch energy system in 205 Treffers, D. J. et al. Energy Policy, 2005, 33, (13), 1723-1743. In this paper, two long-term visions of the Dutch future energy system are composed, analysed and evaluated. Both visions were set up to meet the requirement to reduce the greenhouse gas (GHG) emissions with 80% in 2050 in comparison to 1990. The two visions start from very different perspectives and contexts. Quantitative analysis shows that when economic growth and energy use follow a business as usual development, emissions of GHGs can increase up to 250% of 1990 levels. The two, rather opposing, visions show that it is feasible to combine (strong) economic growth with far going reduction of G H G emissions, provided a number of key options are developed and applied. These options were chosen and discussed during several meetings by stakeholders in a dialogue process, using feedback from scientists, and consist of improvements in energy efficiency in industry, CO2 neutral feedstocks for transportation, renewable energy and highly insulated buildings in the built environment and improvements in the primary production of the agricultural sector. It is clear that drastic changes in many areas in society are required to obtain the desired GHG-emission levels in 2050. The results also show though, that such a
development can be realized in different ways. In other words, there are various ways to implement a low G H G emission economy in the long term.
05•02650 Hierarchically structured exergetic and exergoeconomic analysis and evaluation of energy conversion processes Hebecker, D. et al. Energy Conversion and Management, 2005, 46, (7 8), 1247-1266. Evaluation of the efficiency and economic benefit of energy conversion processes and technologies requires a scientifically based analysis. The hierarchically structured exergetic analysis provides a detailed characterization of complex technical systems. By defining corresponding evaluation coefficients, the exergetic efficiency can be assessed for units within the whole system. Based on this exergetic analysis, a thermo-economic evaluation method is developed. A cost function is defined for all units, subsystems and the total plant, so that the cost flow in the system can be calculated. Three dimensionless coefficients, the Pauer factor, the loss coefficient and the cost factor, enable pinpointing cost intensive process units, allocating cost in cases of coproduction and gaining insight for future design improvements. The methodology is demonstrated by a biomass gasification plant producing electricity, heat and cold.
05/02651 Managing a reservoir-based hydro-energy plant: building understanding in the buy and sell decisions in a changing environment van Ackere, A. et al. Energy Policy, 2005, 33, (7), 939-947. This paper describes a modelling process at a Norwegian chemical producer, who owns 20% of a reservoir based hydro-energy plant. While the initial objective was to increase the profitability of the energy plant (in particular by an improved understanding of buying and selling decisions and a reconciliation of the managerial and engineering points of view in the context of a liberalized energy market) the process resulted in the company's decision to refocus on its core-business. The process illustrates how a modelling process can lead to a fundamental reframing of the issue, resulting in major change for the company.
05•02652 Multi-criteria analysis of alternative-fuel buses for public transportation Tzeng, G.-S. et al. Energy Policy, 2005, 33, (11), 1373 1383. The technological development of buses with new alternative fuels is considered in this paper. Several types of fuels are considered as alternative-fuel modes, i.e. electricity, fuel cell (hydrogen), and methanol. Electric vehicles may be considered the alternative-fuel vehicles with the lowest air pollution. Hybrid electric vehicles provide an alternate mode, at least for the period of improving the technology of electric vehicles. A hybrid electric vehicle is defined as a vehicle with the conventional internal combustion engine and an electric motor as its major sources of power. Experts from different decision-making groups performed the multiple attribute evaluation of alternative vehicles. AHP is applied to determine the relative weights of evaluation criteria. TOPSIS and VIKOR are compared and applied to determine the best compromise alternative fuel mode. The result shows that the hybrid electric bus is the most suitable substitute bus for Taiwan urban areas in the short and median term. But, if the cruising distance of the electric bus extends to an acceptable range, the pure electric bus could be the best alternative.
05/02653 PEM electrolysis for production of hydrogen from renewable energy sources Barbir, F. Solar Energy, 2005, 78, (5), 661 669. PEM electrolysis is a viable alternative for generation of hydrogen from renewable energy sources. Several possible applications are discussed, including grid independent and grid assisted hydrogen generation, use of an electrolyser for peak shaving, and integrated systems both grid connected and grid independent where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed. Specific issues regarding the use of PEM electrolyser in the renewable energy systems are addressed, such as sizing of electrolyser, intermittent operation, output pressure, oxygen generation, water consumption and efficiency.
05•02654 Potential applications of renewable energy sources, biomass combustion problems in boiler power systems and combustion related environmental issues Demirbas, A. Progress in Energy and Combustion Science, 2005, 3 l, (2), 171 192. This paper describes the potential applications of renewable energy sources to replace fossil fuel combustion as the prime energy sources in various countries, and discusses problems associated with biomass combustion in boiler power systems. Here, the term biomass includes organic matter produced as a result of photosynthesis as well as municipal, industrial and animal waste material. Brief summaries of the basic concepts involved in the combustion of biomass fuels are
Fuel and Energy Abstracts
November 2005 387