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Abstract(s)
O trabalho desenvolvido e exposto nesta dissertação teve por objetivo fundamentar de forma
rigorosa a ideia de que – as energias renováveis não são responsáveis por emissões de CO2 –
não é de todo correta. Ele incide apenas sobre a fonte de energia eólica e embora a captura e
conversão desta em eletricidade constitua uma alternativa cada vez mais competitiva e amiga
do ambiente constataremos no final o valor aproximado das emissões indiretas de CO2eq por
cada kWh de eletricidade produzido.
O estudo iniciou-se com uma caracterização pormenorizada do recurso eólico, o vento, como
fonte de energia natural e renovável, dando especial ênfase à sua quantificação ou intensidade
em cada local, em termos de número de horas, de velocidade e do tipo de escoamento.
Seguindo-se uma análise da evolução histórica das tecnologias utilizadas na sua captura desde
a idade média até ao início dos anos 80, período a partir do qual foi intensificada a investigação
com vista a maximizar os benefícios da sua exploração.
Analisam-se depois as principais tecnologias de captura de energia eólica hoje em uso, que
assentam em turbinas de eixo horizontal e de eixo vertical, as máquinas elétricas utilizadas na
conversão de energia mecânica em elétrica, os sistemas de controlo e todos os outros principais
componentes.
Com a edificação de uma instalação para captura de energia eólica há inevitavelmente emissões
devidas ao fabrico dos componentes e demais atividades envolvidas. As emissões associadas a
cada dependem da sua constituição, da quantidade e diversidade de materiais, da distância de
onde provém, do tipo de transporte utilizado, entre outros. A sua contabilização exaustiva é do
âmbito do Bill of Material (BOM), onde é feita uma lista dos materiais e componentes
envolvidos para termos um aerogerador ou parque eólico pronto a entrar em operação e também
do Life Cycle Assessment (LCA), onde são quantificados os impactes ambientais associados a
todas as etapas do ciclo de vida do parque eólico.
Na sequência da contabilização das emissões de CO2 associadas a cada material utilizado, ao
seu transporte, instalação e manutenção durante o tempo de vida útil, é possível calcular as
emissões totais de CO2eq por MW instalado.
Adicionalmente, para cada localização é possível quantificar o potencial de geração de energia
eólica em MWh por MW instalado, tendo por base o fator de capacidade que depende do
número de horas de disponibilidade do recurso eólico, e calcular depois as emissões indiretas
médias de CO2eq por cada kWh gerado, dividindo as emissões totais pela produção total de
energia.
O valor CO2eq/kWh encontrado reflete assim as emissões indiretas, e reais, associadas a
produção de eletricidade com base no recurso eólico.
ABSTRACT: The work developed in this dissertation aimed to refute the prevalent idea that renewable energies are not responsible for CO2 emissions. This work focused solely on the source of wind energy. Although capturing and converting wind energy into electricity is an increasingly competitive and environmentally friendly alternative, this work revealed there are indirect CO2eq emissions for each kWh of electricity produced by wind turbines. The study began with a detailed characterization of the wind as a source of natural and renewable energy, with special emphasis on its quantification or intensity at each location, in terms of number of hours, speed and type of flow. This is followed by an analysis of the historical evolution of the technologies used in the capture of wind from the Middle Ages to the beginning of the 1980s, a period during which research was intensified to maximize the exploitation of wind energy. The study then analyzes the main wind energy capture technologies in use today, which are based on horizontal axis and vertical axis turbines. These include electrical machines used in the conversion of mechanical energy into electrical energy, control systems and all the other main components. With the construction of an installation to capture wind energy, there are inevitably emissions due to the manufacture of components and other activities involved. The emissions associated with each depend on its constitution, the quantity and diversity of materials, the distance from which it comes, the type of transport used, among others. An exhaustive accounting can be found within the Bill of Material (BOM), where a list of the materials and components involved in order to prepare a wind turbine or wind farm ready to go into operation. Another source used in this study was the Life Cycle Assessment (LCA), where the environmental impacts associated with all stages of the wind farm's life cycle are quantified. Following the accounting of CO2 emissions associated with each material used, its transport, installation and maintenance during its useful life, it is possible to calculate the total CO2eq emissions per MW installed. Additionally, for each location it is possible to quantify the wind power generation potential in MWh per MW installed, based on the capacity factor that depends on the number of hours of availability of the wind resource. The next step is to calculate the average indirect CO2eq emissions per each kWh generated, dividing the total emissions by the total energy production. The study showed that using this method the CO2eq/kWh value found reflects the indirect and actual emissions associated with the production of electricity based on the wind resource.
ABSTRACT: The work developed in this dissertation aimed to refute the prevalent idea that renewable energies are not responsible for CO2 emissions. This work focused solely on the source of wind energy. Although capturing and converting wind energy into electricity is an increasingly competitive and environmentally friendly alternative, this work revealed there are indirect CO2eq emissions for each kWh of electricity produced by wind turbines. The study began with a detailed characterization of the wind as a source of natural and renewable energy, with special emphasis on its quantification or intensity at each location, in terms of number of hours, speed and type of flow. This is followed by an analysis of the historical evolution of the technologies used in the capture of wind from the Middle Ages to the beginning of the 1980s, a period during which research was intensified to maximize the exploitation of wind energy. The study then analyzes the main wind energy capture technologies in use today, which are based on horizontal axis and vertical axis turbines. These include electrical machines used in the conversion of mechanical energy into electrical energy, control systems and all the other main components. With the construction of an installation to capture wind energy, there are inevitably emissions due to the manufacture of components and other activities involved. The emissions associated with each depend on its constitution, the quantity and diversity of materials, the distance from which it comes, the type of transport used, among others. An exhaustive accounting can be found within the Bill of Material (BOM), where a list of the materials and components involved in order to prepare a wind turbine or wind farm ready to go into operation. Another source used in this study was the Life Cycle Assessment (LCA), where the environmental impacts associated with all stages of the wind farm's life cycle are quantified. Following the accounting of CO2 emissions associated with each material used, its transport, installation and maintenance during its useful life, it is possible to calculate the total CO2eq emissions per MW installed. Additionally, for each location it is possible to quantify the wind power generation potential in MWh per MW installed, based on the capacity factor that depends on the number of hours of availability of the wind resource. The next step is to calculate the average indirect CO2eq emissions per each kWh generated, dividing the total emissions by the total energy production. The study showed that using this method the CO2eq/kWh value found reflects the indirect and actual emissions associated with the production of electricity based on the wind resource.
Description
Keywords
Energias Renováveis Energia eólica Aerogerador Bill of Material (BOM) Life Cycle Assessment (LCA) Potencial de geração eólica Emissões indiretas Emissões CO2eq