Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2016-01-27T12:02:02Z No. of bitstreams: 1 arquivototal.pdf: 2243707 bytes, checksum: 00171b11e2c4e62b920d4e821b052696 (MD5) / Made available in DSpace on 2016-01-27T12:02:02Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2243707 bytes, checksum: 00171b11e2c4e62b920d4e821b052696 (MD5) Previous issue date: 2015-09-04 / This M.Sc. dissertation includes four manuscripts, elaborated from the results obtained in a study case carried out at a public hospital in the Paraíba state (northeast Brazil), considering economic, legal and environmental aspects. Photovoltaic solar energy and biomass were included in the polygeneration superstructure for a large-sized consumer center, for distributed energy generation. An optimization model, based on Mixed Linear Integer Programming (MILP), was built and solved for the obtainment of optimal configuration and operation of the energy supply system under economic and environmental viewpoints. Environmental information was generated by the application of the Life Cycle Assessment methodology to the equipment of the superstructure as well as energy resources available. The regulation that encompasses distributed generation in Brazil is studied, in detail, on the basis of comparative law. It was verified, generally, that despite a rather advanced and consolidated regulation is in force, there is still a lack of fiscal and economic incentives to make distributed generation viable in Brazil. The economic optimization suggested the utilization of biomass in boilers for the production of hot water, and when compared to a conventional system, presented an annual cost 10.99% lower. The environmental optimal solution indicated trigeneration to minimize the envitonmental impacts produced by thesupply and conversion energy system. / São apresentados nesta dissertação quatro artigos elaborados a partir dos resultados obtidos no estudo de caso realizado em um hospital público do estado da Paraíba, considerando aspectos econômicos, jurídicos e ambientais. Energia solar fotovoltaica e a biomassa foram incluídas na superestrutura de poligeração de uma unidade consumidora de grande porte, para a geração distribuída de energia. Um modelo de otimização baseado em Programação Linear Inteira Mista (PLIM) foi construído e resolvido para obtenção da solução ótima (configuração e operação otimizadas), desde objetivos econômico e ambiental. Informação ambiental foi gerada pela aplicação da metodologia da Análise de Ciclo de Vida (ACV) para os equipamentos e recursos energéticos da superestrutura. Também se apresenta um estudo, com base no direito comparado, da norma que regula a geração distribuída no Brasil. Verificou-se, de forma geral, que, apesar do Brasil possuir uma legislação bastante avançada e consolidada, ainda se carece de incentivos fiscais e econômicos para tornar a geração distribuída viável. A otimização econômica sugeriu a utilização da biomassa como recurso nas caldeiras para produção de água quente e vapor, e quando comparado a um sistema convencional, apresentou custo anual 10,99% inferior. A solução ambiental otimizada indicou a trigeração para minimizar os impactos ambientais produzidos pelo sistema de abastecimento e conversão de energia.

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-05-24T14:15:12Z No. of bitstreams: 1 arquivototal.pdf: 8882813 bytes, checksum: 447bbc34337976e5c2a098df23cee335 (MD5) / Made available in DSpace on 2017-05-24T14:15:12Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 8882813 bytes, checksum: 447bbc34337976e5c2a098df23cee335 (MD5) Previous issue date: 2015-08-31 / This paper presents the development of a High Performance System (HPS). The project has three setting developed that analyzes the performance in quantity and quality energy for a generator engine Group (GEG) 100 KVA inserted in settings. For each study, the behavior of energy flows are decouple, making it possible to analyze the best structure of the HPS. The unit constituints of the project were a subsystem cooling by absorbing water – ammonia chiller, a heat recover and a biodiesel production plant. It with these subsystems will work separately characterizing them as cogeneration systems. After that it will be integrated all in one system and then classified as trigeneration system. This work also aims to analyze the behavior of electric charges by energy analyzer and temperature by thermal imager. / Este trabalho apresenta o desenvolvimento de um Sistema de Alto Desempenho (SAD). O projeto desenvolvido apresenta três arranjos em que é analisado o desempenho em quantidade e qualidade energética para um grupo motor gerador (GMG) de 100 KVA inserido nos arranjos. Para cada estudo, os comportamentos dos fluxos de energia são distintos, o que possibilitará analisar a melhor estrutura do SAD. As unidades que constituem o projeto são um subsistema de refrigeração por absorção água-amônia, um recuperador de calor e uma usina de produção de biodiesel. Foram realizados ensaios com esses subsistemas individualmente caracterizando-os como sistemas de cogeração. Posteriormente, foram integrados todos em um só sistema, sendo então classificado como sistema de trigeração. Esse trabalho também analisa o comportamento das cargas elétricas por analisador de energia e análise térmica por câmera termográfica.

Utilisation of biomass resources and CO2 abatement systems in currently exploited fossil resource based energy systems are the key strategies in resolving energy sustainability issue and combating against global climate change. These strategies are affected by high energy penalty and high investment. Therefore, it is imperative to assess the viability of these energy systems and further identify niche problem areas associated with energy efficiency and economic performance improvement. The current research work has two parts. The first part presents techno-economic investigation of thermochemical conversion of biomass into the production of fuels (Fischer-Tropsch liquid or methanol) and electricity. The work encompasses centralised bio-oil integrated gasification plant, assuming that the bio-oil is supplied from distributed pyrolysis plant. Bio-oil is a high energy density liquid derived from biomass fast pyrolysis process, providing advantages in transport and storage. Various bio-oil based integrated gasification system configurations were studied. The configurations were varied based on oxygen supply units, once-through and full conversion configurations and a range of capacities from small to large scale. The second part of this thesis considers integration of various CO2 abatement strategies in coal integrated gasification systems. The CO2 abatement strategies under consideration include CO2 capture and storage, CO2 capture and reuse as well as CO2 reuse from flue gas. These facilities are integrated into cogeneration or polygeneration systems. The cogeneration concept refers to the production of combined heat and power while polygeneration concept is an integrated system converting one or more feedstocks into three or more products. Polygeneration is advocated in this work attributed to its high efficiency and lower emission. Furthermore, it can generate a balanced set of products consisting of fuels, electricity and chemicals. It is regarded as a promising way of addressing the future rapidly growing energy demands. A holistic approach using systematic analytical frameworks comprising simulation modelling, process integration and economic analysis has been developed and adopted consistently throughout the study for the techno-economic performance evaluation of decarbonised fossil and bio-oil based systems. Important design methodology, sensitivity analysis of process parameters and process system modifications are proposed. These are to enhance the efficiency as well as lower the economic and environmental impacts of polygeneration systems. A shortcut methodology has also been developed as a decision-making tool for effective selection from a portfolio of CO2 abatement options and integrated systems. Critical and comprehensive analyses of all the systems under considerations are presented. These embrace the impact of carbon tax, product price evaluation and recommendations for sustainability of low carbon energy systems.

The polygeneration is an innovative and sustainable solution which has become an attractive concept. The simultaneous production of electricity, heating and cooling including hot and cold water respectively in autonomous smaller energy systems can manage a more flexible and environmentally friendly system. Furthermore distributed generation and micro scale polygeneration systems can perform the increase of the utilized renewable energy sources in the power generation. The aforementioned energy systems can consist of several power generation units however the low emission levels, the low investment costs and the fuel flexibility of microturbines are some of the reasons that the study of the microturbines in polygeneration systems is a crucial necessity. In this study, an autonomous small-scale polygeneration energy system is investigated and each component is analyzed. The components of the system are a microturbine, a heat recovery boiler, a heat storage system and an absorption chiller. The purpose of this work is the development of a dynamic model in Matlab/Simulink and the simulation of this system, aiming to define the reliability of the model and understand better the behavior of such a system. Special focus is given to the model of the microturbine due to the complexity and the control methods of this system. The dynamic model is mainly based on thermodynamic equations and the control systems of the microturbine on previous research works. The system has as a first priority the electricity supply while thermal load is supplied depending on the electric demand. The thermal load is supplied by hot water due to the heat recovery which takes place at the heat recovery boiler from the flue gases of the microturbine. Additionally the design of the system is investigated and an operational strategy is defined in order to ensure the efficient operation of the system. For this reason, after creating the load curves for a specific load, two different cases are simulated and a discussion is done about the simulation results and the future work.

Solid Oxide fuel cells (SOFC), is one of the fuel cell types with a greater potential as a commercial electrical power generator. As a high temperature fuel cell type (600-1000ºC), presents one of the biggest opportunity to be integrated in a polygeneration system combining it with existing infrastructure to provide heat and power in a efficient way. Furthermore, unlike other types of fuel cells, SOFC can work using a wide variety of fuels, meaning that with some reformation; most of the commercially available fuels can be utilized, and even some relatively sustainable fuels that are not yet commercial, such as gasified biomass. The main part of this thesis focuses on the design of two gasifier models, one for partial oxidation gasification and other for steam gasification, both models where verified using published experimental results and simulations. Afterwards the models were integrated to work with a SOFC system. Several key parameters where analyzed in other have a complete view of the behavior of the system. The system was studied by changing different parameters like fuel cell operating temperature, fuel cell operating pressure, fuel composition, and moisture content. Finally another part of the thesis is to analyze two different systems, one integrating gasifier and SOFC, and other studying the integration of the gasifier system to a combine cycle system, SOFC-Micro Gas Turbine. The study concludes, as expected, that there is an inverse correlation between the moisture level in the fuel and the efficiencies in all the systems. Also the model shows that increasing the cell operating temperature will reduce the number of cell needed in order to achieve the design power output.

Around three-quarters of Bangladeshis (total population 164 million) live in rural areas: only 25% of these households have access to grid electricity with non-reliable supply despite the country’s successful rural electrification program, kerosene is the predominant source for lighting, and woody biomass is virtually the only option available for cooking. Aside from this energy service challenges the rural population also struggles with unsafe drinking water in terms of widespread arsenic contamination of well water. Access to electricity, clean cooking gas, and safe drinking water services are genuine needs of the rural poor and are essential to improving welfare. These needs can be addressed individually or using an integrated approach. Anaerobic digesters are now a proven technology and remain economically promising in the rural setting, where connection to the public electric and gas grids are not available/either not cost effective or feasible, and where energy and water scarcity are severe. As the technologies continue to improve, and as energy and safe water becomes scarce and fossil fuel energy prices rise, renewable energy based services and technological integration becomes more viable techno-economically. In these circumstances, the integration of biogas digester with power generation and water purification unit is an innovative concept that could be applied in remote areas of Bangladesh.   This work presents a new concept for integrated polygeneration and analyzes the techno-economic performance of the scheme for meeting the demand of electricity, cooking energy and safe drinking water of 30 households in a rural village of Bangladesh. This study considers a holistic approach towards tackling both of these issues via integrated renewable energy-based polygeneration employed at the community level. The polygeneration unit under consideration provides electricity via cow dung-fed digester, which in turn is coupled to a gas engine. Excess digester gas is employed for cooking, while waste heat from the process drives a membrane distillation unit for water purification. The specific technologies chosen for the key energy conversion steps are as follows: plug-flow digester; internal combustion engine; and air-gap membrane distillation. The technical features, energy consumption, and potential of renewable energy use in driving the main integrated processes are reviewed and analyzed in this thesis. This study also examines one approach by investigating the application of suitable membrane technologies, specifically air gap membrane distillation (AGMD), as a promising method for small-scale, low cost deployment.    Experimental results show that the tested AGMD prototype is capable of achieving high separation efficiency, as all product water samples showed arsenic levels below accepted limits. Mass flows and energy balance, life cycle cost (levelized cost) of producing electricity, cooking gas and safe drinking water as well as the payback period of such a polygeneration system were studied. The results indicate that this polygeneration system is much more competitive and promising than other available technologies when attempting to solve the energy and arsenic-related problems in Bangladesh. One of the main encouraging issues of this integrated system is the levelized cost of the three major services: cooking gas (0.015 USD/kWh), electricity (0.042 USD/kWh–an orders of magnitude lower than comparable photovoltaic or wind systems) and safe drinking water (0.003 USD/liter). Additionally, the payback period is between 2.6 to 4 years. / <p>QC 20150516</p>

Polygeneration systems attract attention recently because of their high efficiency and low emission compare to the conventional power generation technology. Three different polygeneration systems based on low temperature solid oxide fuel cell, atmospheric solid oxide fuel cell/ micro gas turbine, and pressurized solid oxide fuel cell/ micro gas turbine are mathematically modeled in this study using MATLAB (version 7.12.0.635). These systems are designed to provide space heating, cooling and hot domestic water simultaneously. This report provides the design aspects of such systems. Furthermore, the effects of some important operating properties on the polygeneration systems performance are investigated.

Modelling Polygeneration with Desiccant Cooling System for Tropical(and Sub Tropical) ClimatesAbstractSpace cooling has become a necessity in tropical countries. Maintainingcomfortable indoor conditions in industrial environments incur high energy bills due toheavy dependency on electrically operated air conditioning systems. In order to exploreways and means to improve the energy efficiency and alternative energy resources, afeasibility study was conducted using a transient simulation software TRNSYS toimplement a combined cooling, heating and power system suitable for a tropicalcountry.It is proven from the literature search that desiccant dehumidification inconjunction with evaporative coolers can reduce air conditioning operating costssignificantly since the energy required to power a desiccant cooling system is small andthe source of this required energy can be diverse.(Low exergy heat such as solar, wasteheat and natural gas)This research is conducted to evaluate the performance and applicability ofdesiccant cooling systems under tropical climatic conditions. Two operating modes;ventilation and recirculation modes of solid desiccants based open cycle air conditioningthat use waste heat from a CHP plant are analysed to understand their operatingranges, performances and applicability. The model developed is used to propose asuitable desiccant cooling system for a selected industry environment in Sri Lanka.Preliminary results obtained by a parametric analysis for weather data for Colombo, SriLanka shows 0.95 and 1.02 optimum coefficients of performance for the ventilation andrecirculation modes respectively when heat is available at 85°C. Based on thecomparisons of the analysis it is seen that the desiccant cooling appears to be a logicalsupplement for space cooling applications in tropical climates like Sri Lanka. And for thecase study taken to investigate can be proposed with a desiccant cooling system with ahot water storage as the energy supply and it can maintain a COP of about 0.48 undertropical weather conditions.

Livestock and poultry are two growing subsectors of global farming economy with an impact on the environment and thus deserving closer attention. While the farms play a major role in providing protein essential for human diets, they are also sources of significant amounts of greenhouse gas (GHG) emissions. Hence, the sectors need to improve their environmental performance and mitigate their negative impacts on climate. To estimate the annual GHG emissions from a dairy and poultry farm, a case study was conducted in the rural area of Bangladesh. The study has considered the supply chains of both farms while estimating the emissions.  The study also estimated the GHG emission reduction potential of a small biogas based polygeneration system aimed at providing energy services in the rural area. LCA (lifecycle assessment) has been used as the main tool while estimating the emissions.

The price and accessibility of fossil fuels, especially crude oil, are subject to considerable fluctuations due to growing demand on energy, limited resources, and energy security concerns. In addition, climate change caused by burning of fossil fuels is a challenge that energy sector is currently facing. These challenges incentivize development of alternative processes with no greenhouse gas emissions that can meet transportation fuels, chemical liquids, and electricity demands. Coal-based processes are of particular interest because coal price is both low and stable. However, these processes have a large environmental impact and are also less economically attractive than natural gas based plants due to the recent significant drop in natural gas price. However, even for natural gas plants, attempts to reduce CO2 emissions by using traditional CO2 capture and sequestration technologies not only decrease the thermal efficiency and profitability of the plant significantly but still release some CO2 to the atmosphere. The aim of this thesis is to develop, simulate and optimize an integrated polygeneration plant that uses multiple feedstocks and produces multiple products with low to zero CO2 emissions. Several process alternatives are investigated in this work to show the effect of each feedstock and product on the performance of the proposed plant. A comprehensive study is performed in each section, including process simulation in Aspen Plus software, development of custom models required for some units, as well as cost analysis by using Aspen Icarus software and empirical cost estimations from literature. Moreover, derivative free optimization techniques such as particle swarm optimization (PSO), genetic algorithm (GA) and simulated annealing (SA) are implemented to drive the design to economically optimum conditions as a function of the market price and carbon taxes. The final model will also introduce emerging technologies that can achieve higher efficiency and lower CO2 emissions compared to commercial systems, such as chemical looping gasification, chemical looping combustion, nuclear heat reforming, etc. By integrating multiple feedstocks and processes, the model can exploit certain synergies which are unavailable to traditional plants, resulting in significant efficiency improvements. In addition to power and liquid fuels, this polygeneration process offers benefits for petrochemical plants. Despite limited worldwide crude oil reserves, the demand for petrochemical products is still growing fast and it is highly important for petrochemical industry to find new resources as feedstock and diversify their supply chain network. By integration of the polygeneration plant in the same facility with novel processes that produce olefins (petrochemical feedstock) not from oil, but from syngas, it is possible to supply the required feed at lower cost than commercial steam cracking plants. / Thesis / Doctor of Philosophy (PhD)