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Abstract(s)
No mundo atual, as alterações climáticas impõem metas restritivas para as emissões, sendo marcos os anos de 2030 e 2050. O setor marítimo representa cerca de 2,89% das emissões totais de CO2, resultante das atividades antropogénicas.
O presente estudo avalia as opções de combustíveis alternativos para navios militares da Marinha Portuguesa, de tipologia NPO, com capacidade de combate, num horizonte temporal de aplicação de 10 a 20 anos. Foram avaliadas sete opções de combustíveis alternativos com potencial aplicação para o setor naval, cada uma com vantagens, limitações e considerações técnicas específicas.
A metodologia adotada inicia com a definição de constrangimentos de segurança, que excluem fluidos criogénicos ou armazenados a pressões superiores a 50 bar, seguido de uma análise energética das opções, comparando massa e volume associado ao seu armazenamento. Uma análise de risco foi realizada, com recurso à conjugação do método FMEA, um processo sistemático de avaliação de risco para modos de falha específicos, com a técnica AHP, aplicada para a quantificação dos parâmetros ocorrência, severidade e detetabilidade, por comparação das alternativas par a par.
A Teoria de Dempster-Shafer é uma teoria para o tratamento da incerteza em ambientes de informação incompleta, considerando dois limites, a crença e a plausibilidade. Quatro experts na área, avaliaram os elementos focais propostos, atribuindo massas de probabilidade a cada um dos conjuntos. Os resultados apontam que o conjunto constituído pelos hidrocarbonetos verdes conjuntamente com o metanol, bem como, uma frota diversificada com soluções de hidrocarbonetos verdes, hidrogénio, metanol e outras opções futuras, constituem as opções com maior viabilidade e potencial de aplicação.
In today’s world, climate change imposes restrictive emission reduction goals, with key milestones set for 2030 and 2050. The maritime sector contributes approximately 2,89 percent of total CO2 emissions stemming from human activities. This research assesses alternative fuel options for combat-ready NPO military vessels of the Portuguese Navy, within a temporal framework spanning 10 to 20 years. Seven alternative fuel options, each characterized by distinct advantages, limitations, and technical aspects, were subjected to evaluation. The employed methodology initiates with the delineation of safety constraints, thereby excluding cryogenic substances or those stored under pressures exceeding 50 bar. This was followed by an energy analysis of the available options, entailing a comparative assessment of mass and volume associated with their storage. Furthermore, a risk analysis was conducted by combining the FMEA method, a systematic risk assessment process for specific failure modes, with the AHP technique. This application facilitated the quantification of parameters such as occurrence, severity, and detectability, by a pairwise comparison of the alternatives. The Dempster-Shafer theory is a framework designed to address uncertainty within contexts characterized by incomplete information. It operates within the bounds of two key parameters: belief and plausibility. In this study, four experts evaluated the proposed focal elements, attributing probability masses to each of the sets under consideration. The outcomes of this evaluation highlight that the set comprising green hydrocarbons in conjunction with methanol, along with a diversified fleet featuring green hydrocarbon solutions, hydrogen, methanol, and other prospective alternatives, represent the options characterized by the highest degree of feasibility and potential application.
In today’s world, climate change imposes restrictive emission reduction goals, with key milestones set for 2030 and 2050. The maritime sector contributes approximately 2,89 percent of total CO2 emissions stemming from human activities. This research assesses alternative fuel options for combat-ready NPO military vessels of the Portuguese Navy, within a temporal framework spanning 10 to 20 years. Seven alternative fuel options, each characterized by distinct advantages, limitations, and technical aspects, were subjected to evaluation. The employed methodology initiates with the delineation of safety constraints, thereby excluding cryogenic substances or those stored under pressures exceeding 50 bar. This was followed by an energy analysis of the available options, entailing a comparative assessment of mass and volume associated with their storage. Furthermore, a risk analysis was conducted by combining the FMEA method, a systematic risk assessment process for specific failure modes, with the AHP technique. This application facilitated the quantification of parameters such as occurrence, severity, and detectability, by a pairwise comparison of the alternatives. The Dempster-Shafer theory is a framework designed to address uncertainty within contexts characterized by incomplete information. It operates within the bounds of two key parameters: belief and plausibility. In this study, four experts evaluated the proposed focal elements, attributing probability masses to each of the sets under consideration. The outcomes of this evaluation highlight that the set comprising green hydrocarbons in conjunction with methanol, along with a diversified fleet featuring green hydrocarbon solutions, hydrogen, methanol, and other prospective alternatives, represent the options characterized by the highest degree of feasibility and potential application.
Description
Keywords
Descarbonização Combustíveis Alternativos Análise de Risco Teoria de Dempster-Shafer FMEA-AHP