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The performance of turbo-generators significantly depends on the design of the power turbine. In addition, the thermoelectric generator can convert waste heat into another source of energy. This research aims to design and optimize an integrated turbo-generator and thermoelectric generator for diesel engines. The goal is to generate electricity from the vehicle exhaust gas. Electrical energy is derived from generators using the flow, pressure, and temperature of exhaust gases from combustion engines and heat-waste. In the case of turbo-generators and thermoelectric generators, the system automatically adjusts the power provided by an inverter. Typically, vehicle exhausts are discarded to the environment. Hence, the proposed conversion to electrical energy will reduce the alternator charging system. This work focuses on design optimization of a turbo-generator and thermoelectric generator for 2500 cc. diesel engines, due to their widespread usage. The concept, however, can also be applied to gasoline engines. Moreover, this model is designed for a hybrid vehicle. Charging during running will save time at the charging station. The optimization by variable van angles of 40°, 50°, 62°, 70°, and 80° shows that the best output power is 62°, which is identical to that calculated. The maximum power outputted from the designed prototype was 1262 watts when operating with an exhaust mass flow rate of 0.1024 kg/s at 3400 rpm (high performance of the engine). This research aims to reduce fuel consumption and reduce pollution from the exhaust, especially for hybrid vehicles.

The concentration of solar radiation by either a lens or a mirror is one of the options for practical utilisation of light to obtain higher temperatures. However, it is difficult to maintain high temperatures on the hot side of the module due to solar diurnal motion. This study evaluates the influence of the thermoelectric (TE) output by optical light concentration. Three-dimensional partial differential equations describing heat balance and TE phenomena were simultaneously solved by applying numerical methods, and the temperature distribution in the whole TE module as well as the current density were simulated. It was shown that the three models of light concentration on a single TE module (BiTe-based, four legs having dimensions of 10 mm x 10 mm x 10 mm) generate a similar output in the external load. This happens because the long leg becomes a large thermal resistance, and because the alumina plate (1 mm thick) with a high thermal conductivity covers the top of the TE modules. The homogenised temperature at the hot junctions generates a similar output in all three models when the cold terminals were kept at constant temperature.

In the becoming years, energy demand is expected to grow faster than current needs. Thermoelectric technology works through conversion process from heat energy into electricity directly and vice versa. Thermoelectric device that use for energy conversion from heat into electrical is known as thermoelectric generator (TEG). TEG is made of Bismuth Telluride, Lead Telluride and Silicon Germanium compound which contains figure of merit (ZT). In term of applications, TEG is possible to be applied in extreme condition such as a power supply in the space mission, harvesting heat from transportation vehicle, and getting waste heat from industrial sector. Furthermore thermoelectric generation is possible also to be applied as a micro power generation system which is very useful for electrical source for residential installation. In this paper, a brief review of above applications is presented. Early developed research investigation is carried out for application of thermoelectric generator in residential installation by using biomass wooden-fuel stove. The early result shows that there are amount of heat emitted from the side cylinder cook stove as energy waste. There is a chance and possibility to harvest energy waste in the stove to become electric source and finally this related research effort will increase the efficiency of the electric stove in energy conversion.

Waste heat recovery can apply to a wide range of applications, from transportation, or industries to domestic appliances. Thermoelectric generation technology applied to those cases could produce electrical energy and thus improve their efficiency. A validated computational methodology, which simulates the behavior of any thermoelectric generator and calculates the energy consumption of the auxiliary equipment involved, has been used to determine the potential of waste heat harvesting. The usable energy, the net energy, generated has to be maximized, not only the thermoelectric generation has to be maximized, but also the consumption of the auxiliary equipment has to be minimized, or if possible eliminated. Heat exchangers with a liquid as the heat carrier procure high thermoelectric generations, as their thermal resistances are very low, nevertheless when the consumption of their auxiliary consumption is borne in mind, their use is not that promising. The optimal thermoelectric energy obtained from the flue gases of a real industry using these dissipation systems is 119 MWh/year, while the maximum net energy is 73 MWh/year due to the consumption of the auxiliary equipment. The latest scenario does not only represent a 40% reduction from the optimal thermoelectric generation but also a different optimal working point. The complete elimination of the auxiliary equipment using novel biphasic thermosyphons with free convection at the same application produces a net energy of 128 MWh/year. This novel dissipation technology presents an increase on the thermoelectric generation due to its low thermal resistances, but above all due to the elimination of the auxiliary consumption. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the economic support to this work, included in the DPI2014-53158-R research project.

Waste heat generation has a widespread presence into daily applications, however, due to the low-temperature grade which presents, its exploitation with the most common technologies is complicated. Thermoelectricity presents the possibility of harvesting any temperature grade heat; besides it also includes many other advantages which make thermoelectric generators perfect for generating electric power from waste heat. A prototype divided into two levels along the chimney which uses the waste heat of a combustion has been built. The experimentation has been used to determine the parameters that influence the generation and to validate a generic computational model able to predict the thermoelectric generation of any application, but specially applications where waste heat is harvested. The temperature and mass flow of the flue gases and the load resistance determine the generation, and consequently, these parameters have been included into the model, among many others. This computational model incorporates all the elements included into the generators (heat exchangers, ceramics, unions) and all the thermoelectric phenomena and moreover, it takes into account the temperature loss of the flue gases while circulating along the thermoelectric generator. The built prototype presents a 65 % reduction in the generation of the two levels of the thermoelectric generator due to the temperature loss of the flue gases. The general computational model predicts the thermoelectric generation with an accuracy of the ±12 %. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the economic support to this work, included in the DPI2014-53158-R research project.

A water lens is employed to concentrate sunlight on the surface of a thermoelectric module in order to heat it. This water lens can change its shape flexibly and is adjustable to solar altitudes. The lens shape and light path were simulated for the cases when the light is incident at an angle to the water surface, parallel to the central axis of the half-cylindrical water lens, and when the light is focused on a plate. A condensing ratio larger than 70 is achieved when the incident light is closer to the normal of the water surface and if the optimal lens shape is maintained.

The purpose of this study is to develop flexible and high-efficient thermoelectric water electrolysis system using hot spring water and water of a stream nearby. The system was field tested in 2010 for the first time and several improvements were adopted to the system and field tests were conducted in 2011 and 2012. The consecutive improvements made it possible to produce twice as much hydrogen as before. In addition, we established the method which determines the best connection method of thermoelectric cells under various water temperature combinations.

A thermoelectric (TE) module with two different thermal sources for power generation is studied in this work. Here, a conventional ¬-type module is tilted in the shape of a parallelogram. A numerical analysis is conducted by using the finite volume method to examine threedimensional (3-d) flows of heat and electric charge. The module configuration and the shape of the elements determine the distribution of temperature and current density inside the TE module. Further, the shortest path is chosen preferentially as the path of the current, depending on the geometry of the TE elements. Although the distribution of current density depends greatly on the module configuration, the TE output power is not affected by the parallel and symmetrical configurations in the two equivalent modules. Thus, the conventional TE module with ¬-type elements is the most favorable, and maximum performance is obtained for a tilting angle of 90° because of the lowest internal electric resistance. [doi:10.2320/matertrans.E-M2014822]

Attentions have been paid to wide use of the natural energy while problems such as depletion of the fossil energy, control of greenhouse gases and risk caused by atomic power are faced. In this paper, we aim to realize a small solar power generation system by using solar heat based on thermoelectric generation principle. During the research, firstly, the amount of solar radiation at Fukuroi area where our university is located is calculated. Secondly, a small parabolic collector is used to collect the light and the heat. Thirdly, a thermoelectric generator is designed and manufactured inside which 4 Petier modules are employed. Then, by amounting the thermoelectric generator to the focus part of the parabolic collector, an experiment testing the electricity generation performance of the solar power generation is carried out. It is found that the open voltage reaches 3.9 V when the temperature difference is 40 degree.

The refrigeration process reduces the temperature of a space or a given volume while the power generation process employs a source of thermal energy to generate electrical power. Because of the importance of these two processes, training of engineers in this area is of great interest. In engineering courses it is normally studied the vapor compression and absorption refrigeration, and power generation systems such as gas turbine and steam turbine. Another type of cooling and generation less studied within the engineering curriculum, having a great interest, it is cooling and thermal generation based on Peltier and Seebeck effects. The theoretical concepts are useful, but students have difficulties understanding the physical meaning of their possible applications. Providing students with tools to test and apply the theory in real applications, will lead to a better understanding of the subject. Engineers must have strong theoretical, computational and also experimental skills. A prototype test bench has been built and experimentally validated to perform practical lessons of thermoelectric generation and refrigeration. Using this prototype students learn the most effective way of cooling systems and thermal power generation as well as basic concepts associated with thermoelectricity. It has been proven that students learn the process of data acquisition, and the technology used in thermoelectric devices. These practical lessons are implemented for a 60 people group of students in the development of subject of Thermodynamic including in the Degree in Engineering in Industrial Technologies of Public University of Navarra.

Plant factories have been attracted a great deal of attention because those are less susceptible to the effects of natural disasters. However, fruits or tall plants are difficult to cultivate using only the artificial lighting. Therefore, we were cultivated strawberries as a sample of fruits using only the artificial lighting. A source of the artificial light was used high power LEDs. Results of cultivating strawberries, the products were almost the same plants as growing under half shade. Furthermore, we thought effective use of the waste heat that generated by the high power LEDs. The waste heat of the LEDs was converted into electricity using a thermoelectric conversion element. As a result, the waste heat was able to generate power of 4.81mW in the case of using three LEDs of 3W-type onto Peltier device. To commercialize plant factories, thermoelectric converted power can be utilized effectively

Thermoelectric (TE) generation performance can be enhanced by stacking several TE modules (so-called cascade-type modules). This work presents a design method to optimize the cascade structure for maximum power output. A one-dimensional model was first analyzed to optimize the TE element dimensions by considering the heat balance including conductive heat transfer, Peltier heat, and Joule heat, assuming constant temperatures at all TE junctions. The number of p–n pairs was successively optimized to obtain maximum power. The power output increased by 1.24 times, from 12.7 W in a conventional model to 15.7 W in the optimized model. Secondly, a two-dimensional numerical calculation based on the finite-volume method was used to evaluate the temperature and electric potential distributions. Voltage–current characteristics were calculated, the maximum power output was evaluated, and the efficiencies of two possible models were compared to select the optimal design. The one-dimensional analytical approach is effective for a rough design, and multidimensional numerical calculation is effective for evaluating the dimensions and performance of cascade-type TE modules in detail.

An innovative conversion module (CM) for concentrating solar power applications, named ST2G (Solar Thermionic-Thermoelectric Generator), has been developed and fabricated. The new technology is based on a solid-state converter that works at temperatures up to 1000 °C and exploits a double conversion stage: a thermionic stage and a thermoelectric one, connected thermally in series. Potentially, the CM could reach a combined solar energy-to-electrical efficiency larger than 30%, producing also additional thermal energy to be exploited as a co-generation. Different prototypes have been fabricated and the discussion on the technological key-points has been reported, relating them to the physical requirements necessary for an efficient conversion mechanism. The preliminary results obtained at a lab-level are here discussed, indicating low electrical power output, but also how to increase the performance by solving the identified issues.

Thermoelectric generators (TEGs) are currently being explored for their potential in harvesting energy from automobile exhaust. TEGs in form of an appropriate TEG- Heat exchanger module can utilize the temperature difference between the hot exhaust gases and the automobile coolant and convert it into electrical voltage. The amount of power is anticipated to be a few hundred watts depending on the temperature gradient and the material of the TEGs. The focus of this study is increasing the hot side heat transfer for improved performance of the thermoelectric generators using two different internal fins — louvered fins and herringbone wavy fins. The multi-louvered fins basically have 'multi flat plate' behavior and will enhance the heat transfer by deflecting the air from its original path and aligning it with the plane of the louvers. Herringbone fins are used to lengthen the path of airflow allowing for greater residence time and better mixing of the flow. They also provide for greater wetted surface area achieving higher heat transfer. The flow and heat transfer behavior inside the exhaust pipe test section with internal fins is modeled using commercial numerical software. The thermal and flow behavior through both these internal fins depends to a large extent on geometric parameters and fin arrangement. Optimization of the fin design is considered to determine the configuration that provides highest heat transfer while providing least pressure drop across the pipe length. The heat transfer and pressure drop characteristics are compared to the baseline flow without any fin enhancement. Master of Science

The final publication is available at Springer via http://dx.doi.org/10.1007/s11664-014-3057-x The reduction of the thermal resistances of the heat exchangers of a thermoelectric generation system (TEG), leads to a significant increase in the TEG efficiency. For the cold side of a thermoelectric module (TEM), a wide range of heat exchangers has been studied, form simple finned dissipators to more complex water (water-glycol) heat exchangers. As Nusselt numbers are much higher in water heat exchangers than in conventional air finned dissipators, convective thermal resistances are better. However, to conclude which heat exchanger leads to higher efficiencies, it is necessary to include the whole system involved in the heat dissipation, that is, TEM-to-water heat exchanger, water-to-ambient heat exchanger, as well as the required pumps and fans. This paper presents a dynamic computational model able to simulate the complete behavior of a TEG, including both heat exchangers. The model uses the heat transfer and hydraulic equations to compute TEM-to-water and water-to-ambient thermal resistances, along with the resistance of the hot side heat exchanger at different operating conditions. Likewise, the model includes all the thermoelectric effect with temperature-dependent properties. The model calculates the net power generation at different configurations, providing a methodology to design and optimize the heat exchange in order to maximize the net power generation for a whole variety of TEGs. The authors are indebted to the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund for economic support of this work, included in the DPI2011-24287 Research Project.

Esta es la versión no revidada del artículo: Rodríguez, A., Astrain, D., Martínez, A. et al. Experimental Study and Optimization of Thermoelectricity-Driven Autonomous Sensors for the Chimney of a Biomass Power Plant. Journal of Elec Materi 43, 2415–2419 (2014). Se puede consultar la versión publicada en http://doi.org/10.1007/s11664-014-3097-2 In the work discussed in this paper a thermoelectric generator was developed to harness waste heat from the exhaust gas of a boiler in a biomass power plant and thus generate electric power to operate a flowmeter installed in the chimney, to make it autonomous. The main objective was to conduct an experimental study to optimize a previous design obtained after computational work based on a simulation model for thermoelectric generators. First, several places inside and outside the chimney were considered as sites for the thermoelectricity-driven autonomous sensor. Second, the thermoelectric generator was built and tested to assess the effect of the cold-side heat exchanger on the electric power, power consumption by the flowmeter, and transmission frequency. These tests provided the best configuration for the heat exchanger, which met the transmission requirements for different working conditions. The final design is able to transmit every second and requires neither batteries nor electric wires. It is a promising application in the field of thermoelectric generation. The authors are indebted to the Spanish Ministry of Economy and Competitiveness, and the European Regional Development Fund for economic support to this work, included in the DPI2011-24287 research project.

Este trabalho apresenta um estudo de Qualidade de Energia Elétrica (QEE) no sistema elétrico industrial de uma concessionária geradora de energia elétrica do Brasil. O estudo teve enfoque na distorção harmônica gerada nos serviços auxiliares da usina termoelétrica. Para tanto, foi necessária a simulação e análise da planta da termoelétrica, com atenção nos serviços auxiliares pertencentes a ela, devido aos altos níveis de distorções harmônicas registrados. A simulação foi feita com o programa ATP (Alternative Transients Program) no domínio do tempo, através de sua interface gráfica, o ATP Draw. Nele foram modelados os principais componentes que pertencem ao Sistema Elétrico de Potência (SEP) em questão, como geradores, transformadores, linhas e cargas não lineares. Com a modelagem do SEP da termoelétrica, é possível determinar os níveis da distorção harmônica em diversos locais da planta, e aprofundar o estudo para que seja possível fazer a mitigação desses distúrbios. A diminuição da distorção harmônica junto ao aumento do fator de potência permite um melhor desempenho da usina, aumentando a faturamento da empresa através do aumento da energia entregue ao sistema elétrico. This dissertation presents a study of Power Quality in an electrical system of a thermoelectric power plant in Brazil. The study focused on the harmonic distortion generated in the auxiliary services of the plant. Therefore, it was necessary to simulate and analyze the thermal plant, with attention to auxiliary services belonging to it, due to high levels of harmonic distortion registered. The simulation was performed using the ATP (Alternative Transients Program) in the time domain through its interface, the ATP Draw. It were modeled the main components that belong to the Power System in question, such as generators, transformers, lines and non-linear loads. With the modeling of the thermoelectric plant, is possible to determine the levels of harmonic distortion at various locations within the plant. The reduction of harmonic distortion along with the increase of power factor allows a better plant performance, increasing company revenue by increasing the energy delivered to the electrical system.

Thermoelectric generators (TEGs) are currently a topic of interest in the field of energy harvesting for automobiles. In applying TEGs to the outside of the exhaust tailpipe of a vehicle, the difference in temperature between the hot exhaust gases and the automobile coolant can be used to generate a small amount of electrical power to be used in the vehicle. The amount of power is anticipated to be a few hundred watts based on the temperatures expected and the properties of the materials for the TEG. This study focuses on developing efficient heat exchanger modules for the cold side of the TEG through the analysis of experimental data. The experimental set up mimics conditions that were previously used in a computational fluid dynamics (CFD) model. This model tested several different geometries of cold side sections for the heat exchanger at standard coolant and exhaust temperatures for a typical car. The test section uses the same temperatures as the CFD model, but the geometry is a 1/5th scaled down model compared to an full-size engine and was fabricated using a metal-based rapid prototyping process. The temperatures from the CFD model are validated through thermocouple measurements, which provide the distribution of the temperatures across the TEG. All of these measurements are compared to the CFD model for trends and temperatures to ensure that the model is accurate. Two cold side geometries, a baseline geometry and an impingement geometry, are compared to determine which will produce the greater temperature gradient across the TEG. Master of Science

This work presents the design and development of a thermoelectric generator intended to harness waste heat in a biomass power plant, and generate electric power to operate sensors and the required electronics for wireless communication. The first objective of the work is to design the optimum thermoelectric generator to harness heat from a hot surface, and generate electric power to operate a flowmeter and a wireless transmitter. The process is conducted by using a computational model, presented in previous papers, to determine the final design that meets the requirements of electric power consumption and number of transmissions per minute. Finally, the thermoelectric generator is simulated to evaluate its performance. The final device transmits information every 5 s. Moreover, it is completely autonomous and can be easily installed, since no electric wires are required. The authors are indebted to the Spanish Ministry of Science and Innovation (DPI2011-24287) and FEDER funds (European Union) for economic support of this work.

According to different sources, from forty to sixty percent of the overall energy generated in the world today is squandered in waste heat. The existing energy conversion technologies are either close to their efficiency limits or too costly to justify their implementation. Therefore, the development of new technological approaches for waste heat recovery is highly demanded. The field of thermoelectrics can potentially provide an inexpensive, clean and efficient solution to waste heat underutilization, given that a new type of thermoelectric materials capable of meeting those requirements are available. This thesis reports on strategies to optimize a thermoelectric efficiency (ZT) of conducting polymers, more specifically poly(3,4-ethylenedioxythiophene) (Pedot). Conducting polymers constitute a special class of semiconductors characterized by low thermal conductivity as well as electrical conductivity and thermopower that can be readily modified by doping in order to achieve the best combination of thermoelectric parameters. Conducting polymers that have never previously been regarded as hypothetically compatible for thermoelectric energy conversion, can exhibit promising thermoelectric performance at moderate temperatures, which is a sought-after quality for waste heat recovery. A rather substandard thermoelectric efficiency of Pedot-Pss can be markedly improved by various secondary dopants whose addition usually improves polymer’s morphology accompanied by a drastic increase in electrical conductivity and, consequently, in ZT. In order to enable further enhancement in thermoelectric properties, the optimization of the charge carrier concentration is commonly used. The oxidation level of Pedot-Pss can be precisely controlled by electrochemical doping resulting in a tenfold increase of ZT. In contrast to Pedot-Pss, another conducting polymer Pedot-Tos exhibits superior thermoelectric performance even without secondary doping owning to its partially crystalline nature that allows for an improved electronic conduction. With the aid of a strong electron donor, positively doped Pedot-Tos gets partially reduced reaching the optimum oxidation state at which its thermoelectric efficiency is just four times smaller than that of Be2Te3 and the highest among all stable conducting polymers. The downsides associated with chemical doping of Pedot-Tos such as doping inhomogeneity or chemical dopants air sensitivity can be surmounted if the doping level of Pedot-Tos is controlled by acidity/basicity of the polymer. This approach yields similar maximum thermoelectric efficiency but does not necessitate inert conditions for sample preparation. Optimized Pedot-Tos/Pedot-Pss can be functionalized as a p-type material in organic thermogenerators (OTEG) to power low energy electronic devices. If printed on large areas, OTEGs could be used as an alternative technique for capturing heat discarded by industrial processes, households, transportation sector or any natural heat sources for electricity production.

Made available in DSpace on 2015-04-11T13:47:53Z (GMT). No. of bitstreams: 1 Whylker Frota.pdf: 831426 bytes, checksum: 85b7070b88b58686155dc241d8fa9435 (MD5) Previous issue date: 2011-12-20 Coordena????o de Aperfei??oamento de Pessoal de N??vel Superior This study investigated the economic impacts caused by substitution of fuel oil derived from oil to gas, from the Solim??es Basin Petroleum, city of Coari (AM), the electrical grid of the city of Manaus - Amazonas state. The study was done through a scene analysis which considers the gas volume and the period specified in the contract, supplying natural gas to the thermal park of Manaus until December 2030. The methodology was based on aspects of electricity generation, energy consumption and cost of fuels (derived from petroleum and natural gas) in order to set the avoided cost of the fuels replacement, as well as present a study of Thermal Plants modulation indicating a better energy efficiency for the use of the volume of gas already contracted. Thus, the research permitted to: (a) identify the avoided cost, with the replacement of fuels to the existing thermoelectric park in the city of Manaus, will be around R$ 1 billion (US$ 529 million) per year from the year 2012, and (b) develop a proposal to use the entire volume of natural gas contracted for electric power generation, with the implementation of a power plant with gas turbines in combined cycle size from 500 to 600 MW of installed rated power, resulting in an increase of about 80% generation capacity with natural gas, as well as an energetic efficiency gain of about 28% in the thermoelectric park system currently installed in Manaus Electric System. Este trabalho objetivou estudar os impactos econ??micos decorrentes da substitui????o dos ??leos combust??veis derivados de petr??leo pelo g??s natural, proveniente da Bacia Petrol??fera do Solim??es, munic??pio de Coari (AM), na matriz el??trica da cidade de Manaus estado do Amazonas. O estudo foi feito atrav??s de uma an??lise de cen??rio que considera o volume de g??s e o prazo de dura????o definidos pelo contrato de fornecimento do g??s natural para o parque t??rmico de Manaus at?? dezembro de 2030. A metodologia foi baseada nos aspectos de gera????o de eletricidade, consumo e custo dos energ??ticos (??leos derivados de petr??leo e g??s natural), visando definir o custo evitado com a substitui????o dos combust??veis, bem como apresentar um estudo de modula????o de usinas t??rmicas que indique uma melhor efici??ncia energ??tica para a utiliza????o do volume de g??s contratado. Dessa forma, a pesquisa permitiu: (a) identificar que o custo evitado, com a substitui????o dos energ??ticos para o parque t??rmico existente na cidade de Manaus, ser?? da ordem de R$ 1 bilh??o (US$ 529 milh??es) por ano a partir do ano de 2012; e (b) desenvolver uma proposta para a utiliza????o de todo o volume de g??s natural contratado para a gera????o de energia el??trica, com a implanta????o de uma usina termel??trica com turbinas ?? g??s em ciclo combinado do porte de 500 a 600 MW de pot??ncia nominal instalada, resultando em um aumento da ordem de 80% na capacidade de gera????o a g??s natural, bem como um ganho de efici??ncia energ??tica de aproximadamente 28% no parque termel??trico instalado atualmente no Sistema Manaus.

The rice husk production in Rio Grande do Sul, state responsible for more than half of this cereal s country production, leads to the need of an appropriate environmental management in view the impacts produced by this residue in the environment, whether they be local or global, like greenhouse effect impacts. Therefore, a rational utilization of this energetic resource in small thermal power plants may guarantee the environmental adequation of the company, filling the requirements needed to sustainable production, at the same time in which may provide financial attractiveness to necessary investments to this objective. The development of the technology known as MCT allowed existent small thermoelectrical potentials, originated from the decentralized husk production, to be attended in a satisfactory way, but needing an environmental and economical analysis. For that reason, this study had as objective the gathering of rice production and beneficiation data on the State which can provide the evaluation of the rice husk availableness and furthermore to grant a thermal electrical potential analysis current on Rio Grande do Sul. Intending to award the units which do not have this economic and environmental analysis, it has been continued the financial analysis of the MCT s investments, to power plants bellow 800 kW, including the economic impacts of the carbon credits (CC) trade. Through indicators as IRR, payback, NPV and generation cost, associated to the impacts of the environmental quality caused by the CC trade, it has been possible to prove that, for scales smaller than 400 kW, there is no economic feasibility, unless they receive tributary incentives, whether for a short period, as a diminish of the finance interest rate and/or the raise of the exceeding tradable energy selling price, as shown on the sensitivity analysis made. It has been also evaluated the operation and obtained results of the MCT installed on the city of São Pedro do Sul, which demonstrate the difficulties found in the small scale thermoelectrical biomass generation. These difficulties can be modified if they would be set as priority, by programs of incentive, the use of biomass on decentralized electric energy generation. A produção de casca de arroz no Rio Grande do Sul, estado responsável por mais da metade da produção desse cereal no país, conduz a necessidade de uma adequada gestão ambiental, tendo em vista os impactos gerados por esse resíduo no meio ambiente, sejam eles locais ou globais, como os do efeito estufa. Assim, a utilização racional desse recurso energético em pequenas centrais termoelétricas pode garantir a adequação ambiental da empresa, preenchendo os requisitos necessários à produção sustentável, ao mesmo tempo em que pode proporcionar certa atratividade financeira aos investimentos necessários a esse fim. O desenvolvimento da tecnologia denominada MCT permitiu que os pequenos potenciais termoelétricos existentes, decorrentes da produção descentralizada de casca, fossem atendidos de forma satisfatória, porém carecendo de uma análise econômico-ambiental. Dessa forma, este estudo objetivou o levantamento de dados de produção e beneficiamento de arroz no Estado de forma a permitir a avaliação da disponibilidade de casca, de maneira a subsidiar uma conseqüente análise do potencial termoelétrico existente no Rio Grande do Sul. Com vistas a contemplar as unidades desprovidas dessa avaliação econômico-ambiental, deu-se seguimento a análise financeira de investimentos em MCT s, para potências menores que 800 kW, incluindo-se os impactos econômicos da comercialização dos créditos de carbono (CC). Através de indicadores como TIR, payback, VPL e custo de geração, em associação aos impactos de qualidade ambiental efetivados pela comercialização dos CC, foi possível comprovar que para as escalas inferiores a 400 kW não há viabilidade econômica, a menos que essas usufruam de incentivos fiscais, ainda que temporários, como diminuição da taxa de juros do financiamento e/ou aumento do valor pago pela energia elétrica excedente comercializável, como demonstrado na análise de sensibilidade realizada. Também foi avaliado o funcionamento e os resultados obtidos pela MCT instalada no município de São Pedro do Sul, comprovando as dificuldades encontradas na geração termoelétrica à biomassa em pequena escala, passíveis de alteração se priorizados por programas de incentivo ao uso de biomassa na geração descentralizada de energia elétrica.

Paralelo entre os impactos ambientais das usinas hidrelétricas .e termoelétricas demonstra a importância dos programas de conservação de energia. Comparison between the environmental impacts from the hydroelectric and thermoelectric dams shows the importance of the energy conservation programs.

The stability of output performance plays a very important role in the thermoelectric generation (TEG) system, but the fluctuation problem of heat source widely exists in the industry which releases the waste heat, and the fluctuating process will cause the instability and low efficiency of the TEG system. In this article, a novel TEG system with thermal switch was proposed to solve this serious problem. In order to get the detailed characteristics of the TEG system with thermal switch, experimental and dynamic modelling methods were used. The experimental and modelling results show that the thermal switch can efficiently reduce the temperature fluctuation and increase the output power and efficiency of the TEG system, and there is an optimal turning on temperature and turning off temperature to maximally increase the output power and electricity efficiency of the TEG system. The comparison between the numerical data and the experimental results has approved the reasonability of the dynamic model.