O bambu e uma graminea lenhosa, renovavel, perene e com boa produtividade de biomassa por hectare. Pode ser cultivada praticamente em todo o territorio brasileiro, que esta quase todo localizado em regioes tropicais e chuvosas, oferecendo excelentes condicoes para a producao e o uso energetico da biomassa de bambu em larga escala. O setor de papel e celulose apresenta boas perspectivas na producao de papel de fibras longas utilizando bambu, no entanto, apenas duas empresas brasileiras utilizam esse tipo de biomassa em grande escala no Brasil: O Grupo Penha queima o bambu em caldeira e utiliza o vapor no processo de reciclagem de papel e O Grupo Joao Santos utiliza a biomassa como materia prima na fabricacao de papel e celulose. No entanto, em ambos os casos a biomassa nao e utilizada em sistema de cogeracao de eletricidade, considerada uma tecnologia eficiente de conversao. O objetivo dessa tese e estudar os aspetos tecnicos, economicos e ambientais da implantacao de um sistema de cogeracao de eletricidade utilizando biomassa de bambu. Sao estudadas as caracteristicas agronomicas e as particularidades da implantacao de cultivos comerciais de bambu voltado a fins energeticos. Visando determinar o Poder Calorifico (PCS) de cinco diferentes especies consideradas adaptadas ao clima brasileiro e conhecidas como boas produtoras de biomassa por hectare, foram realizado ensaios em laboratorio empregando a bomba calorimetrica, possibilitando identificar variacoes do poder calorifico entre as especies estudadas. Considerando o dado referente aos processos das empresas e pesquisa em literatura, os resultados apontam que e tecnicamente possivel cogerar eletricidade de modo eficiente, queimando 17 toneladas de bambu por hora e gerar 3.5 MW. No entanto, o sistema nao apresenta viabilidade economica em funcao do modelo de atual adotado pelas empresas no manejo de seus cultivos. Em relacao aos aspectos ambientais, por ser uma planta perene, capaz de produzir biomassa anualmente sem replantio, pode ser uma excelente opcao para estocar carbono. / Bamboo is a grass, woody perennial with good biomass productivity per hectare. Bamboo can be grown virtually anywhere in the Brazilian territory and almost all existing plantations are located in tropical and rainy areas, offering excellent conditions for the production and use of biomass energy in large scale. Two Brazilian companies already utilize bamboo biomass in large scale in Brazil. The Penha Group, in Bahia, burns bamboo in boilers and uses the steam in the process for recycling paper. Joao Santos Group uses bamboo as raw material in the manufacture of pulp and paper. However in any case there is the use of this biomass for energy cogeneration, which is the most efficient technology for energy conversion. Therefore, this thesis analyses the use of bamboo as fuel for electricity cogeneration in Brazil considering the technical aspects, as well as the corresponding economic and environmental system deployment. Also, to study the development of the productive chain of bamboo in large scale in Brazil, specifically targeted for energy purposes, this paper presents the survey of data concerning the different production systems adopted by companies, both in the cultivation and processing of biomass. Based in these results it is analyzed an efficient cogeneration system using bamboo as fuel on large scale. Obtained results show that the power to be produced in an efficient cogeneration system (60 bar, 490 oC), from 17 tones of bamboo per hour, is 3,5 MW but, with the existing bamboo production models, there is no economic feasibility, as discussed in the paper. Regarding environmental aspects, it must be noted that the bamboo is as perennial plant, able to produce biomass annually without replanting, and so appears to be an excellent carbon sink.

Biomass-fed cogeneration units and waste incinerators have the advantages of producing efficiently heat and power and of reducing the amount of CO2 emitted per produced energy. However, they produce toxic polychlorinated VOCs (dioxins), CO and NOx. This thesis aims at developing a catalytic system for the total oxidation of chlorinated VOCs that: i) convert efficiently chlorinated VOCs below 250 °C and ii) resist to the exhaust co-pollutants (H2O, CO, NOx). Moreover, this thesis aims at having a complete understanding of the catalytic mechanism. Part I demonstrated that VOx/TiO2 based catalysts are very efficient in the total oxidation of chlorobenzene (taken as a model molecule). In particular, they proved to be highly resistant against deactivation. Moreover, Part I established that the addition of secondary phases producing VOx-WOx/TiO2 or VOx-MoOx/TiO2 induces a synergetic effect that improves the performances. Furthermore, the replacement of a classical TiO2 by a sulfated one improves the catalytic activity. In Part II, the investigation of the co-pollutants influence on the catalysts performances demonstrated their quite good resistance. Indeed, the presence of CO does not induce any deactivation of the catalysts while NOx induces a huge improvement of the catalysts ability to destroy chlorinated VOCs. This beneficial effect is explained by the in situ production of a strong oxidant (NO2) that speeds up the reoxidation of the reduced VOx sites. Nevertheless, H2O vapor can affect negatively the catalyst activity when present in a high concentration. Part III, by revisiting catalytic and characterization results exposed in Part I and II, demonstrated that the catalytic mechanism proceeds in four steps: i) adsorption of chlorinated VOCs on Brønsted sites, ii) VOx redox sites give some of their lattice oxygen atoms to oxidize the aromatic ring producing H2O and COx, iii) reoxidation of the VOx reduced sites thanks to the gas stream oxidant (O2) and iv) retrieving of the chlorine from the surface. The second and third steps compose a Mars and van Krevelen mechanism and the third one is the mechanism rate limiting step. Our work shows that the performances can be improved by tuning the redox properties of the VOx phases: i) improvement of the reducibility and ii) stabilization of the vanadium oxidation level above a limit value, estimated around 4.87.

Small combined heat and power generators have the potential to reduce energy consumption and greenhouse gas emissions of residential buildings. Recently, much attention has been given to these units. To date, the majority of studies in this field have concentrated on the steady operational performance of a specific generator type, and the available computer models have largely been theoretical in nature. <br /><br /> The main goal of this study was to evaluate the performance of the latest combined heat and power generators, when integrated into Canadian residential homes. A fair comparison of four 1 kW (electrical) units was made. The combined heat and power units studied were based on PEM fuel cell, solid oxide fuel cell, Stirling Engine, and internal combustion engine energy converters. <br /><br /> This study utilized recent test data in an attempt to evaluate the most efficient method of integrating the combined heat and power units into residential houses. Start-up, shut down, and load change transients were incorporated into the simulations. The impact of load variations due to building thermal envelope differences and varying building heating system equipment was evaluated. The simulations were evaluated using TRNSYS software. The building heat demands were determined with eQuest hourly building simulation software. <br /><br /> All of the combined heat and power units under study were capable of providing a net annual benefit with respect to global energy and greenhouse gas emissions. The fuel cells offer the highest integrated performance, followed closely by the internal combustion engine and lastly the Stirling engine. Annual global energy savings up to 20%, and greenhouse gas savings up to 5. 5 tonnes per year can be achieved compared to the best conventional high efficiency appliances. <br /><br /> Heat demand influences performance greatly. As the thermal output of the generator unit approaches half of the average building thermal demand, the system design becomes critical. The system design is also critical when integrating with a forced air furnace. Only the PEM fuel cell unit produces clear global energy and emissions benefits when operating in the summertime.

In recent years, there has been significant pressure to reduce greenhouse gas emissions, to achieve higher efficiency and to integrate greater amounts of renewable energy resources in energy system. Governments at all levels have recognized the environmental impacts of the energy sector, as well as the ways in which this sector is closely-linked to a range of economic issues (e.g., industrial development, inflationary prices and local economic development). In general, every effort has been made to cope with the challenges in providing a sustainable energy solution for achieving the goals. Even though the concept of “Smart Grid” has recently been highlighted in the electricity sector to improve efficiency of energy use and to reduce greenhouse gases to achieve business goals, the driving initiatives for generating a Smart Grid are straightforward and its scope and functions differ from a Smart Energy Network (SEN) which has a broader boundary and more components. A comprehensive concept of SEN beyond Smart Grid is presented to effectively integrate energy systems which can not only cover available energy resources but also address sustainability issues. The availability of new technologies for utilizing the renewable energy such as solar, wind and biomass, and reducing the carbon footprint of fossil fuels by including natural gas within an integrated energy network provides a base for better conservation of energy usage and providing a cleaner environment. Moreover, the new energy carriers such as hydrogen and sustainable natural gas integrated into cogeneration systems should be taken into account when such a network is developed. A cogeneration system is a promising solution for effectively supplying energy to district consumers for high density urban environment. In this thesis, a new community-scale cogeneration system is modeled using TRNSYS (Transient System Simulation) software, which enables analysis of transient characteristics of cogeneration and to investigate critical factors which should be considered for successful integration into a SEN. This thesis focuses on defining what a Smart Energy Network is, its functions and the critical criteria of demonstrating and validating this concept, and developing a model for cogeneration system according to the concept of Smart Energy Network.

The extraction-condensing cogeneration system is a popular technology for heat and power integration which can be used by petrochemical process. To compare with back pressure system, extraction-condensing system has better flexibility for process control. However, the thermal efficiency of extraction- condensing system could be affected by the amount of effective heat to process. If the effective heat to process and the plant power demand were not well designed, the cogeneration system may violate government regulation of ¡§qualified cogeneration system¡¨ by MOEA, or the system economics can not meet investor¡¦s requirement. From another point of view, if the cogeneration system bias original design operating condition or it has to run under low loading, the energy efficiency will move away from the target. A 94.9 MW extraction-condensing system of a petrochemical plant was selected as an example. For the purpose of data requisition, the author established a model to predict main steam flow, extraction steam flow, and power generation load. Moreover, a set of equations for the calculation of heat rate of turbine plant was developed. Besides, a Microsoft Excel calculation sheet was programmed to compute real time plant thermal efficiency. The actual operation data was compared with computer simulation. Results show (1) To meet the regulation, the process steam shall exceed 100 t/h with rated power generation. (2) For the minimum generator load (about 20 MW), the effective heat to process must exceed 78% in order to ensure a 52% overall thermal efficiency. (3) Low load means low thermal efficiency of this system. Some energy conservation ideas of this cogeneration system were assessed. Four ideas were presented, including (1) Increase boiler feed water temperature during low evaporation load. (2) Recovering of flash steam vented from blow down tank for the heating of boiler combustion air. (3) Control of cooling tower fans speed by using frequency inverter. (4) Utilization of hydraulic coupled forced draft fan. The total benefit of these energy conservation ideas is 2,546.44 kilo-liter fuel oil equivalent.

Co-generation is an efficient energy system that generates steam and electricity simultaneously. In ordinary operation, fuel cost accounts for more than 60% of the operational cost. As a result, the boiler efficiency and optimization level of co-generation are both high. To achieve further energy conservation, objectives of this thesis are to find the Profit-maximizing dispatch and efficiency enhancing strategy of the co-generation systems under deregulation. In a coexistent environment of both Bilateral and Poolco-based power market, there are bid-based spot dispatch, and purchases and sales agreement-based contract dispatch. For profit-maximizing dispatch, the steam of boilers, fuels and generation output will be obtained by using the SQP(Sequential Quadratic Programming ) method. In order to improve the boiler efficiency, this thesis utilizes artificial neural networks(ANN) and evolutionary programming(EP) methods to search for the optimal operating conditions of boilers. A co-generation system (back-pressure type and extraction type) is used to illustrate the effectiveness of the proposed method.

In this thesis, load scheduling problem for cogeneration plants is interpreted in the context of stochastic programming. Cogeneration (CHP) is an important technology in energy supply of many countries. Cogeneration plants are designed and operated to cover the requested time varying demands in heat and power. Load scheduling of cogeneration plants represents a multidimensional optimization problem, where heat and electricity demands, operational parameters and associated costs exhibit uncertain behavior. Cogeneration plants are characterized by their &lsquo / heat to power ratio&rsquo / . This ratio determines the operating conditions of the plant. However, this ratio may vary in order to adapt to the physical and economical changes in power and to the meteorological conditions. Employing reliable optimization models to enhance short term scheduling capabilities for cogeneration systems is an important research area. The optimal load plan is targeted by achieving maximum revenue for cogeneration plants. Revenue is defined for the purpose of the study as the sales revenues minus total cost associated with the plant operation. The optimization problem, which aims to maximize the revenue, is modeled by thermodynamic analyses. In this context, the study introduces two objective functions: energy based optimization, exergy-costing based optimization. A new method of stochastic programming is developed. This method combines dynamic programming and genetic algorithm techniques in order to improve computational efficiency. Probability density function estimation method is introduced to determine probability density functions of heat demand and electricity price for each time interval in the planning horizon. A neural network model is developed for this purpose to obtain the probabilistic data for effective representation of the random variables. In this study, thermal design optimization for cogeneration plants is also investigated with particular focus on the heat storage volume.

ABSTRACT With the development of high-tech industry, the power quality has become a critical issue for the industrial customers in science park. The voltage sag and power system stability problems due to fault contingency in Taipower network has caused serious production loss. The manufacturing process platforms, which are driven by power electronics equipments may shutdown when the voltage dip exceeds 30% and it will take long time for the restoration of production. To enhance the service reliability and power quality, the new cogeneration system in Hsin Chu Science Park has been selected for case study to solve the problems of short circuit capacity and voltage sag. The short circuit analysis by both ANSI and IEC is performed to find the magnitudes of fault currents. The transient stability analysis is executed to identify the critical clearing time to support the design of protective relays for tie line tripping. The static var compensator (SVC) is also considered in the simulation to investigate the mitigation of system voltage drop due to fault contingency. It is found that the implementation of cogenerators and SVC can improve the electricity service quality for high-tech customers with proper design of industrial power systems.

No description available.

In recent years, there has been significant pressure to reduce greenhouse gas emissions, to achieve higher efficiency and to integrate greater amounts of renewable energy resources in energy system. Governments at all levels have recognized the environmental impacts of the energy sector, as well as the ways in which this sector is closely-linked to a range of economic issues (e.g., industrial development, inflationary prices and local economic development). In general, every effort has been made to cope with the challenges in providing a sustainable energy solution for achieving the goals. Even though the concept of “Smart Grid” has recently been highlighted in the electricity sector to improve efficiency of energy use and to reduce greenhouse gases to achieve business goals, the driving initiatives for generating a Smart Grid are straightforward and its scope and functions differ from a Smart Energy Network (SEN) which has a broader boundary and more components. A comprehensive concept of SEN beyond Smart Grid is presented to effectively integrate energy systems which can not only cover available energy resources but also address sustainability issues. The availability of new technologies for utilizing the renewable energy such as solar, wind and biomass, and reducing the carbon footprint of fossil fuels by including natural gas within an integrated energy network provides a base for better conservation of energy usage and providing a cleaner environment. Moreover, the new energy carriers such as hydrogen and sustainable natural gas integrated into cogeneration systems should be taken into account when such a network is developed. A cogeneration system is a promising solution for effectively supplying energy to district consumers for high density urban environment. In this thesis, a new community-scale cogeneration system is modeled using TRNSYS (Transient System Simulation) software, which enables analysis of transient characteristics of cogeneration and to investigate critical factors which should be considered for successful integration into a SEN. This thesis focuses on defining what a Smart Energy Network is, its functions and the critical criteria of demonstrating and validating this concept, and developing a model for cogeneration system according to the concept of Smart Energy Network.