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Abstract(s)
O mundo enfrenta desafios crescentes em termos de energia e emissões devido ao
aumento do consumo de combustíveis fósseis. Para descarbonizar a economia, diferentes
vetores energéticos, como o hidrogénio e o amoníaco, tem vindo a ser considerados. Esta
dissertação visa avaliar a eficiência energética e as exigências de energia no transporte de
hidrogénio via amoníaco, comparando-o com diferentes fluidos, nomeadamente o gás natural
e o hidrogénio gasoso, para tubagens com diâmetros de 300, 400 e 500 mm, e um comprimento
fixo de 200 km, operando a 298 K. A rugosidade interna das tubagens foi mantida constante em
0,015 mm, e a pressão de operação foi fixada em 5 MPa. Calcularam-se detalhadamente as
perdas de carga ao longo das tubagens, assim como a potência de compressão e a taxa de
energia despendida.
Os resultados mostram que, para todos os diâmetros, o transporte de hidrogénio
gasoso apresenta maiores perdas de carga do que o gás natural. Ambos apresentam perdas
superiores às do amoníaco líquido nas mesmas condições de transporte, devido à viscosidade
cinemática. Além disso, o transporte de hidrogénio gasoso requer maior trabalho de
compressão comparado ao gás natural, enquanto o trabalho de compressão necessário para o
gás natural e o hidrogénio é superior ao trabalho de bombagem para o amoníaco líquido nas
mesmas condições.
O transporte de hidrogénio via amoníaco requer menos energia por unidade de energia
transportada em comparação com o gás natural e o hidrogénio. Isto deve-se à maior densidade
volumétrica de energia do amoníaco, que permite um caudal volúmico menor, resultando numa
perda de carga reduzida, tornando o amoníaco uma opção mais eficiente e economicamente
viável para o transporte de energia a grandes distâncias.
Também foram analisados os custos de capital relacionados com a construção e
operação dos gasodutos. Para o gás natural e o hidrogénio gasoso, os custos de material foram
idênticos, dado o uso do mesmo tipo de aço (L290) e condições de transporte. Contudo, o
transporte de hidrogénio via amoníaco, que requer um aço de alta resistência (P265NL),
apresentou custos de material superiores devido à maior espessura necessária e ao custo mais
elevado do material.
Os custos totais, incluindo material e instalação, aumentam significativamente com o
diâmetro da tubagem. No caso do transporte de hidrogénio via amoníaco, os custos foram
consistentemente mais altos em comparação com o gás natural e o hidrogénio, devido à
complexidade do material e às especificações técnicas exigidas. A análise dos custos anuais de
capital, nivelados ao longo de 40 anos com uma taxa de juros de 8%, destaca a diferença nos
custos operacionais entre os fluidos. O transporte de hidrogénio via amoníaco, embora
energeticamente mais eficiente, apresenta custos de capital mais elevados, especialmente para
tubagens de maior diâmetro.
The world is facing growing challenges in terms of energy and emissions due to the increased consumption of fossil fuels. To decarbonize the economy, different energy carriers, such as hydrogen and ammonia, have been considered. This dissertation aims to evaluate the energy efficiency and energy requirements of hydrogen transport through ammonia, comparing it with different fluids, namely natural gas and gaseous hydrogen, in pipelines with diameters of 300, 400, and 500 mm, and a fixed length of 200 km, operating at 298 K. The internal roughness of the pipelines was kept constant at 0,015 mm, and the operating pressure was set at 5 MPa. Detailed calculations were made for pressure losses along the pipelines, as well as for compression power and energy consumption. The results show that, for all diameters, the transportation of gaseous hydrogen presents higher pressure losses than natural gas. Both present higher losses than liquid ammonia under the same transport conditions, due to kinematic viscosity. Additionally, the transportation of gaseous hydrogen requires more compression work compared to natural gas, while the compression work required for natural gas and hydrogen is higher than the pumping work for liquid ammonia under the same conditions. Hydrogen transport through ammonia requires less energy per unit of energy transported compared to natural gas and hydrogen. This is due to the higher volumetric energy density of ammonia, which allows for a lower volumetric flow rate, resulting in reduced pressure losses, making ammonia a more efficient and economically viable option for longdistance energy transport. Capital costs related to the construction and operation of the pipelines were also analysed. For natural gas and gaseous hydrogen, the material costs were identical, given the use of the same type of steel (L290) and transport conditions. However, hydrogen transport through ammonia, which requires high-strength steel (P265NL), showed higher material costs due to the increased thickness required and the higher cost of the material. Total costs, including material and installation, increase significantly with the diameter of the pipeline. In the case of hydrogen transport through ammonia, the costs were consistently higher compared to natural gas and hydrogen, due to the complexity of the material and the required technical specifications. The analysis of annual capital costs, levelled over 40 years with an interest rate of 8%, highlights the differences in operational costs between the fluids. Hydrogen transport through ammonia, although more energy-efficient, presents higher capital costs, especially for larger diameter pipelines.
The world is facing growing challenges in terms of energy and emissions due to the increased consumption of fossil fuels. To decarbonize the economy, different energy carriers, such as hydrogen and ammonia, have been considered. This dissertation aims to evaluate the energy efficiency and energy requirements of hydrogen transport through ammonia, comparing it with different fluids, namely natural gas and gaseous hydrogen, in pipelines with diameters of 300, 400, and 500 mm, and a fixed length of 200 km, operating at 298 K. The internal roughness of the pipelines was kept constant at 0,015 mm, and the operating pressure was set at 5 MPa. Detailed calculations were made for pressure losses along the pipelines, as well as for compression power and energy consumption. The results show that, for all diameters, the transportation of gaseous hydrogen presents higher pressure losses than natural gas. Both present higher losses than liquid ammonia under the same transport conditions, due to kinematic viscosity. Additionally, the transportation of gaseous hydrogen requires more compression work compared to natural gas, while the compression work required for natural gas and hydrogen is higher than the pumping work for liquid ammonia under the same conditions. Hydrogen transport through ammonia requires less energy per unit of energy transported compared to natural gas and hydrogen. This is due to the higher volumetric energy density of ammonia, which allows for a lower volumetric flow rate, resulting in reduced pressure losses, making ammonia a more efficient and economically viable option for longdistance energy transport. Capital costs related to the construction and operation of the pipelines were also analysed. For natural gas and gaseous hydrogen, the material costs were identical, given the use of the same type of steel (L290) and transport conditions. However, hydrogen transport through ammonia, which requires high-strength steel (P265NL), showed higher material costs due to the increased thickness required and the higher cost of the material. Total costs, including material and installation, increase significantly with the diameter of the pipeline. In the case of hydrogen transport through ammonia, the costs were consistently higher compared to natural gas and hydrogen, due to the complexity of the material and the required technical specifications. The analysis of annual capital costs, levelled over 40 years with an interest rate of 8%, highlights the differences in operational costs between the fluids. Hydrogen transport through ammonia, although more energy-efficient, presents higher capital costs, especially for larger diameter pipelines.
Description
Keywords
Hydrogen Ammonia Gas pipeline Oil pipeline Pressure loss Energy vector Hidrogénio Amoníaco Gasodutos Oleodutos Perda de carga Vetor energético