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Avaliação do potencial produtivo de biomassa de resíduos agrícolas no Alentejo em função das características do solo
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Os combustíveis fósseis são a principal fonte de energia. O fato de serem uma fonte não renovável, aos efeitos negativos sobre o meio ambiente associados com o aumento da população mundial e as elevadas necessidades, obrigam a procurar fontes alternativas e sustentáveis. A biomassa vegetal, um subproduto da produção agrícola, é uma fonte disponível em grandes quantidades e poderá ser uma alternativa/ complementar às outras fontes de energia renovável. Este trabalho apresenta uma avaliação do potencial produtivo da biomassa agrícola na região do Alentejo. Caracterizou-se os parâmetros físico-químicos do solo que influenciam a produtividade agrícola, bem como à inventariação da produtividade da biomassa nos três distritos do Alentejo e à caracterização de diferentes biomassas para avaliar o potencial de produção da energia, em particular biocombustíveis gasosos que possam ser utilizados em motores diesel em modo dual fuel. Para a estimativa de produtividade da biomassa foram utilizadas imagens Satélite Sentinel-2 do Sensor MSI com uma resolução espacial de 10 m, utilizadas para a classificação das classes de ocupação do solo e o cálculo do índice de vegetação por diferença normalizada (NDVI). O resultado do cálculo do potencial produtivo da biomassa mostrou que no Alentejo se obtém uma boa quantidade de biomassa agrícola e o distrito de Beja apresentou-se como o de maior produtividade de biomassa logo seguido pelos distritos de Évora e Portalegre. No distrito de Portalegre, concelho de Elvas estimou-se em cerca de 15 237 ton/ano a biomassa agrícola produzida e que é capaz de gerar 14 825 MWh de energia elétrica, correspondente a 20% de energia elétrica total atualmente consumida no concelho. Para a caracterização do solo, analisaram-se amostras do solo recolhidas em parcelas experimentais do INIAV, Pólo de Inovação de Elvas na Herdade da Comenda com culturas anuais e na Herdade do Reguengo com culturas do olival. Os resultados analíticos determinados no Laboratório da ESA de Elvas revelaram que os parâmetros estão em conformidade com o Manual de Fertilização do solo e com a classificação FAO e na classificação SROA/ CNROA/IEADR. Os valores dos índices nutricionais em macronutrientes comparados com os valores de referência, não condicionam a produtividade das culturas. Avaliação do potencial produtivo de biomassas de resíduos agrícolas no Alentejo em função do solo. Para o aproveitamento energético da biomassa agrícola pela tecnologia da gaseificação, fez-se a caracterização das biomassas agrícolas recolhidas na mesma área de estudo do solo. A caracterização baseou-se na análise imediata, elementar e Poder calorifico Superior, e os resultados demonstraram que as biomassas analisadas não apresentaram risco ambiental nem necessidade de um pré-tratamento termoquímico; as biomassas da palha de trigo, cevada e centeio apresentam um baixo conteúdo carbónico e um baixo potencial energético e apenas a biomassas da poda de oliveira apresentou um conteúdo carbónico dentro da faixa esperada e um potencial energético considerável, com características adequadas para a produção de biocombustíveis usados em motores duo fuel. Desta forma conclui-se que a biomassa de subprodutos agrícolas tem potencialidades para poder ser uma excelente fonte complementar de energia renovável. A biomassa da poda do olival destacou-se como a biomassa obtida em maior quantidade, com maior conteúdo energético e menor teor de humidade e é uma biomassa de derivada de uma cultura que produzida em grande quantidade e se adapta a vários tipos de solo
Fossil fuels are the main source of energy. The fact that they are a non-renewable source, the negative effects on the environment associated with the increase in the world's population and the high needs, force the search for alternative and sustainable sources. Plant biomass, a by-product of agricultural production, is a source available in large quantities and could be an alternative/complementary to other sources of renewable energy. This work presents an evaluation of the productive potential of agricultural biomass in the Alentejo region. The physicochemical parameters of the soil that influence agricultural productivity were characterized, as well as the inventory of biomass productivity in the three districts of Alentejo and the characterization of diferente biomasses to assess the potential for energy production, in particular gaseous biofuels that can be used in diesel engines in dual fuel mode. To estimate biomass productivity, Satellite Sentinel-2 images from the MSI Sensor were used with a spatial resolution of 10 m, used for classifying land cover classes, and calculating the vegetation index by normalized difference (NDVI). The result of the calculation of the productive potential of biomass showed that in Alentejo a good amount of agricultural biomass is obtained, and the district of Beja presented itself as the one with the highest productivity of biomass, followed by the districts of Évora and Portalegre. In the district of Portalegre, municipality of Elvas, an estimated 15237 ton/year of agricultural biomass is produced, which can generate 149825 MWh of electricity, corresponding to 20% of the total electricity currently consumed in the municipality. For the characterization of the soil, soil samples collected in experimental plots of the INIAV, Pole de Inovação de Elvas at Herdade da Comenda with annual crops and at Herdade do Reguengo with olive groves were analysed. The analytical results determined at the ESA Laboratory in Elvas revealed that the parameters are inaccordance with the Soil Fertilization Manual and with the FAO classification and the SROA/CNROA/IEADR classification. The values of the nutritional indices in macronutrients compared with the reference values, do not condition the productivity of the cultures. For the energy use of agricultural biomass by gasification technology, the characterization of agricultural biomass collected in the same soil study area was carried out. The characterization was based on immediate, elemental and Higher Calorific Power analysis, and the results showed that the analyzed biomass did not present an environmental risk or the need for a thermochemical pre-treatment; the biomass of wheat, barley and rye straw has a low carbon content and a low energy potential and only the biomass of olive tree pruning showed a carbon content within the expected range and a considerable energy potential, with suitable characteristics or the production of biofuels used in duo fuel engines. In this way, it is concluded that the biomass of agricultural by-products has the potential to be an excellent complementary source of renewable energy. The olive tree pruning biomass stood out as the biomass obtained in greater quantity, with higher energy content and lower moisture content and is a biomass derived from a culture that is produced in large quantities and adapts to various types of soil.
Fossil fuels are the main source of energy. The fact that they are a non-renewable source, the negative effects on the environment associated with the increase in the world's population and the high needs, force the search for alternative and sustainable sources. Plant biomass, a by-product of agricultural production, is a source available in large quantities and could be an alternative/complementary to other sources of renewable energy. This work presents an evaluation of the productive potential of agricultural biomass in the Alentejo region. The physicochemical parameters of the soil that influence agricultural productivity were characterized, as well as the inventory of biomass productivity in the three districts of Alentejo and the characterization of diferente biomasses to assess the potential for energy production, in particular gaseous biofuels that can be used in diesel engines in dual fuel mode. To estimate biomass productivity, Satellite Sentinel-2 images from the MSI Sensor were used with a spatial resolution of 10 m, used for classifying land cover classes, and calculating the vegetation index by normalized difference (NDVI). The result of the calculation of the productive potential of biomass showed that in Alentejo a good amount of agricultural biomass is obtained, and the district of Beja presented itself as the one with the highest productivity of biomass, followed by the districts of Évora and Portalegre. In the district of Portalegre, municipality of Elvas, an estimated 15237 ton/year of agricultural biomass is produced, which can generate 149825 MWh of electricity, corresponding to 20% of the total electricity currently consumed in the municipality. For the characterization of the soil, soil samples collected in experimental plots of the INIAV, Pole de Inovação de Elvas at Herdade da Comenda with annual crops and at Herdade do Reguengo with olive groves were analysed. The analytical results determined at the ESA Laboratory in Elvas revealed that the parameters are inaccordance with the Soil Fertilization Manual and with the FAO classification and the SROA/CNROA/IEADR classification. The values of the nutritional indices in macronutrients compared with the reference values, do not condition the productivity of the cultures. For the energy use of agricultural biomass by gasification technology, the characterization of agricultural biomass collected in the same soil study area was carried out. The characterization was based on immediate, elemental and Higher Calorific Power analysis, and the results showed that the analyzed biomass did not present an environmental risk or the need for a thermochemical pre-treatment; the biomass of wheat, barley and rye straw has a low carbon content and a low energy potential and only the biomass of olive tree pruning showed a carbon content within the expected range and a considerable energy potential, with suitable characteristics or the production of biofuels used in duo fuel engines. In this way, it is concluded that the biomass of agricultural by-products has the potential to be an excellent complementary source of renewable energy. The olive tree pruning biomass stood out as the biomass obtained in greater quantity, with higher energy content and lower moisture content and is a biomass derived from a culture that is produced in large quantities and adapts to various types of soil.
Description
Keywords
Solo Ocupação de Solo Deteção Remota NDVI Biomassa agrícola. Land Occupation of the Land Remote Sensing NDVI, Agricultural biomass