• Energy Research
• 13. Climate action close
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A crescente procura energética a nível mundial, aliada à importância do tratamento das águas residuais, acentua a necessidade de se aumentar a auto-suficiência energética e económica das estações de tratamento de águas residuais (ETAR), aproveitando as suas potencialidades de produção energética. A presente dissertação empreende uma avaliação dos consumos energéticos de uma ETAR portuguesa de lamas ativadas de tamanho médio (ETAR Paço de Sousa) e propõe o dimensionamento de um sistema fotovoltaico, o seu contributo energético e a sua viabilidade económica. No estudo preliminar dos consumos energéticos construiu-se o diagrama de carga horária. Os parafusos de Arquimedes e os arejadores (reatores SBR) da digestão aeróbia foram identificados como sendo os maiores consumidores, correspondendo a 60,1% dos gastos energéticos. Nesta avaliação foram elaborados alguns indicadores de desempenho energético (IDEs), que se mostraram bastante positivos. O dimensionamento do sistema fotovoltaico (FV) foi realizado em parceria com a MEGAJOULE II, SA. Como a ETAR Paço de Sousa integra um sistema de cogeração de biogás, com venda do excedente à rede, foram considerados 2 cenários para o sistema FV. O cenário 1 previa cobrir por completo as necessidades energéticas da ETAR, não contabilizando o contributo do sistema de cogeração, mas devido às limitações impostas pela área, este teve por base a cobertura de toda a área disponível, prevendo a instalação de 420 kW. O cenário 2 considera o contributo de 70% da cogeração, sendo dimensionado para cobrir as necessidades do mês de maior consumo energético, estimando-se uma instalação de 377 kW. No estudo, foram detalhadas todas as perdas de produção de origem ótica, as perdas relativas ao módulo, as perdas elétricas e as perdas por sujidade. Obteve-se uma razão de desempenho anual médio de 0,805 para o cenário 1 e de 0,789 para o cenário 2. A produção energética estimada para o ano de instalação foi de 548 233 kWh para o cenário 1 e de 493 362 kWh para o cenário 2. Foram registadas perdas de 97,281 kWh para o cenário 1, valor inferior aos 133,681 kWh obtidos para o cenário 2. É previsto um lucro final de 836 665,59 € após os 25 anos para o cenário 1, valor que excede os 789 883,05 € referentes ao rendimento total para o cenário 2. O retorno do investimento inicial foi obtido no 8ºano para o cenário 1 e 7ºano para o cenário 2. Recomendou-se a escolha do cenário 1, pois apresenta um maior lucro final, assegurando, em média, 32,4% dos gastos económicos da ETAR, visando uma auto-suficiência económica média total de 94,3%. No futuro, a auto-suficiência económica total poderá ser atingida, caso haja uma alocação da intensidade dos consumos para um regime diurno de forma a evitar excedentes de energia, aliada à instalação de sobrepressores mais eficientes, para a digestão aeróbia. The growing energy demand worldwide, combined with the importance of wastewater treatment, emphasizes the need to increase the energy and economic self-sufficiency of wastewater treatment plants (WWTP), taking advantage of their energy production potentialities. The present dissertation undertakes an assessment of the energy consumption of a medium-sized Portuguese WWTP of activated sludge (WWTP Paço de Sousa) and proposes the sizing of a photovoltaic system, its energy contribution and its economic viability. In the preliminary study of energy consumption, the hourly load diagram was constructed. Archimedes' screws and aerators (SBR reactors) of aerobic digestion were identified as the largest consumers, matching 60.1% of the energy expenditure. In this evaluation, some energy performance indicators (IDEs) were elaborated, proving to be very positive. The design of the PVSystem was carried out in partnership with MEGAJOULE II, SA. As the WWTP Paço de Sousa integrates a biogas cogeneration system, with the sale of surplus to the grid, 2 scenarios were considered for the PVSystem. Scenario 1 intended to fully cover the energy needs of the WWTP, not accounting for the contribution of the cogeneration system, but due to the limitations imposed by the area, it was based on covering the entire available area, foreseeing the installation of 420 kW. Scenario 2 considers the contribution of 70% from the cogeneration system, being dimensioned to cover the needs of the month with the highest energy consumption, estimating an installation of 377 kW. In the study, all production losses, such as optical, losses related to the module, electrical losses and soiling losses were detailed. An average annual performance ratio of 0,805 for scenario 1 and 0,789 for scenario 2 was obtained. The estimated energy production for the year of installation was 548 233 kWh for scenario 1 and 493 362 kWh for scenario 2, decreasing over the 25 year-life of the PVSystem. Losses of 97,281 kWh were recorded for scenario 1, surprisingly lower than the 133,681 kWh obtained for scenario 2. A final profit of 836 665,59 € after 25 years is predicted for scenario 1, a value that exceeds the 789 883,05 € referring to the total income for scenario 2. The return on the initial investment was obtained in the 8th year for scenario 1 and 7th year for scenario 2. The choosing of scenario 1 was recommended, as it presents a higher final profit, ensuring, on average, 32.4% of the WWTP's economic expenses, aiming at a total average economic self-sufficiency of 94.3%. In the future, total economic self-sufficiency may be achieved if there is an allocation of the intensity of consumption to a daytime regime, avoiding energy surpluses, combined with the installation of more efficient superpressors for aerobic digestion. Dissertação de mestrado em Ciências e Tecnologias do Ambiente (especialização em Energia)

A crescente procura energética a nível mundial, aliada à importância do tratamento das águas residuais, acentua a necessidade de se aumentar a auto-suficiência energética e económica das estações de tratamento de águas residuais (ETAR), aproveitando as suas potencialidades de produção energética. A presente dissertação empreende uma avaliação dos consumos energéticos de uma ETAR portuguesa de lamas ativadas de tamanho médio (ETAR Paço de Sousa) e propõe o dimensionamento de um sistema fotovoltaico, o seu contributo energético e a sua viabilidade económica. No estudo preliminar dos consumos energéticos construiu-se o diagrama de carga horária. Os parafusos de Arquimedes e os arejadores (reatores SBR) da digestão aeróbia foram identificados como sendo os maiores consumidores, correspondendo a 60,1% dos gastos energéticos. Nesta avaliação foram elaborados alguns indicadores de desempenho energético (IDEs), que se mostraram bastante positivos. O dimensionamento do sistema fotovoltaico (FV) foi realizado em parceria com a MEGAJOULE II, SA. Como a ETAR Paço de Sousa integra um sistema de cogeração de biogás, com venda do excedente à rede, foram considerados 2 cenários para o sistema FV. O cenário 1 previa cobrir por completo as necessidades energéticas da ETAR, não contabilizando o contributo do sistema de cogeração, mas devido às limitações impostas pela área, este teve por base a cobertura de toda a área disponível, prevendo a instalação de 420 kW. O cenário 2 considera o contributo de 70% da cogeração, sendo dimensionado para cobrir as necessidades do mês de maior consumo energético, estimando-se uma instalação de 377 kW. No estudo, foram detalhadas todas as perdas de produção de origem ótica, as perdas relativas ao módulo, as perdas elétricas e as perdas por sujidade. Obteve-se uma razão de desempenho anual médio de 0,805 para o cenário 1 e de 0,789 para o cenário 2. A produção energética estimada para o ano de instalação foi de 548 233 kWh para o cenário 1 e de 493 362 kWh para o cenário 2. Foram registadas perdas de 97,281 kWh para o cenário 1, valor inferior aos 133,681 kWh obtidos para o cenário 2. É previsto um lucro final de 836 665,59 € após os 25 anos para o cenário 1, valor que excede os 789 883,05 € referentes ao rendimento total para o cenário 2. O retorno do investimento inicial foi obtido no 8ºano para o cenário 1 e 7ºano para o cenário 2. Recomendou-se a escolha do cenário 1, pois apresenta um maior lucro final, assegurando, em média, 32,4% dos gastos económicos da ETAR, visando uma auto-suficiência económica média total de 94,3%. No futuro, a auto-suficiência económica total poderá ser atingida, caso haja uma alocação da intensidade dos consumos para um regime diurno de forma a evitar excedentes de energia, aliada à instalação de sobrepressores mais eficientes, para a digestão aeróbia. The growing energy demand worldwide, combined with the importance of wastewater treatment, emphasizes the need to increase the energy and economic self-sufficiency of wastewater treatment plants (WWTP), taking advantage of their energy production potentialities. The present dissertation undertakes an assessment of the energy consumption of a medium-sized Portuguese WWTP of activated sludge (WWTP Paço de Sousa) and proposes the sizing of a photovoltaic system, its energy contribution and its economic viability. In the preliminary study of energy consumption, the hourly load diagram was constructed. Archimedes' screws and aerators (SBR reactors) of aerobic digestion were identified as the largest consumers, matching 60.1% of the energy expenditure. In this evaluation, some energy performance indicators (IDEs) were elaborated, proving to be very positive. The design of the PVSystem was carried out in partnership with MEGAJOULE II, SA. As the WWTP Paço de Sousa integrates a biogas cogeneration system, with the sale of surplus to the grid, 2 scenarios were considered for the PVSystem. Scenario 1 intended to fully cover the energy needs of the WWTP, not accounting for the contribution of the cogeneration system, but due to the limitations imposed by the area, it was based on covering the entire available area, foreseeing the installation of 420 kW. Scenario 2 considers the contribution of 70% from the cogeneration system, being dimensioned to cover the needs of the month with the highest energy consumption, estimating an installation of 377 kW. In the study, all production losses, such as optical, losses related to the module, electrical losses and soiling losses were detailed. An average annual performance ratio of 0,805 for scenario 1 and 0,789 for scenario 2 was obtained. The estimated energy production for the year of installation was 548 233 kWh for scenario 1 and 493 362 kWh for scenario 2, decreasing over the 25 year-life of the PVSystem. Losses of 97,281 kWh were recorded for scenario 1, surprisingly lower than the 133,681 kWh obtained for scenario 2. A final profit of 836 665,59 € after 25 years is predicted for scenario 1, a value that exceeds the 789 883,05 € referring to the total income for scenario 2. The return on the initial investment was obtained in the 8th year for scenario 1 and 7th year for scenario 2. The choosing of scenario 1 was recommended, as it presents a higher final profit, ensuring, on average, 32.4% of the WWTP's economic expenses, aiming at a total average economic self-sufficiency of 94.3%. In the future, total economic self-sufficiency may be achieved if there is an allocation of the intensity of consumption to a daytime regime, avoiding energy surpluses, combined with the installation of more efficient superpressors for aerobic digestion. Dissertação de mestrado em Ciências e Tecnologias do Ambiente (especialização em Energia)

Several factors and processes, both natural and anthropogenic, can threaten the integrity of any geosite, leading to their degradation. For this reason, geoheritage degradation risks should be considered a fundamental step in any geoconservation strategy, all the more when the aim is to tackle the effects of climate change. The present work proposes a quantitative methodology for the degradation risk assessment of geosites by considering the extrinsic factors that can damage the geoheritage. The methodology has been tested on the Maltese Islands, where considerable previous research has been undertaken in order to highlight the international significance of the Maltese landscapes. Three criteria to assess the degradation risk are proposed: natural vulnerability, anthropogenic vulnerability and public use. For each criterion, several parameters have been identified in order to propose a detailed numerical evaluation. The results show that the degradation risk of geosites is mainly related to negligence and lack of knowledge of its inherent geological heritage, and which leads to public misuse and mismanagement of the geosites. The results give an overview of the condition of the geosites and provide information for the design and management of suitable protection measures, especially in the light of future threats related to climate change.

Several factors and processes, both natural and anthropogenic, can threaten the integrity of any geosite, leading to their degradation. For this reason, geoheritage degradation risks should be considered a fundamental step in any geoconservation strategy, all the more when the aim is to tackle the effects of climate change. The present work proposes a quantitative methodology for the degradation risk assessment of geosites by considering the extrinsic factors that can damage the geoheritage. The methodology has been tested on the Maltese Islands, where considerable previous research has been undertaken in order to highlight the international significance of the Maltese landscapes. Three criteria to assess the degradation risk are proposed: natural vulnerability, anthropogenic vulnerability and public use. For each criterion, several parameters have been identified in order to propose a detailed numerical evaluation. The results show that the degradation risk of geosites is mainly related to negligence and lack of knowledge of its inherent geological heritage, and which leads to public misuse and mismanagement of the geosites. The results give an overview of the condition of the geosites and provide information for the design and management of suitable protection measures, especially in the light of future threats related to climate change.

Reducing global emissions will require a global cosmopolitan culture built from detailed attention to conflicting national climate change frames (interpretations) in media discourse. The authors analyze the global field of media climate change discourse using 17 diverse cases and 131 frames. They find four main conflicting dimensions of difference: validity of climate science, scale of ecological risk, scale of climate politics, and support for mitigation policy. These dimensions yield four clusters of cases producing a fractured global field. Positive values on the dimensions show modest association with emissions reductions. Data-mining media research is needed to determine trends in this global field.

Reducing global emissions will require a global cosmopolitan culture built from detailed attention to conflicting national climate change frames (interpretations) in media discourse. The authors analyze the global field of media climate change discourse using 17 diverse cases and 131 frames. They find four main conflicting dimensions of difference: validity of climate science, scale of ecological risk, scale of climate politics, and support for mitigation policy. These dimensions yield four clusters of cases producing a fractured global field. Positive values on the dimensions show modest association with emissions reductions. Data-mining media research is needed to determine trends in this global field.