• Energy Research
• 2021-2025close
• 12. Responsible consumption close
• 13. Climate action close
• 15. Life on land close
• University of Minho close

Urban drainage systems face intrinsic constraints related to the deterioration of infrastructure, the interaction between systems, and increasing requirements and stresses that lower the quality of provided services. Furthermore, climate change and the need for the efficient use of resources are providing additional pressures that cannot be addressed solely with “Business-as-usual” solutions. In this paper, the consequences of such problems and limitations on the urban environment have been assessed through the identification of linked major impacts (e.g., urban flooding and pollution events) and societal externalities (e.g., economic losses, health and social issues, and environmental risks). Since Nature-based Solutions (NBS) consider human well-being, socio-economic development, and governance principles, they open new perspectives regarding urban sustainability, quality of life, and climate change adaptation. To highlight their added value to existing Urban Drainage Systems (UDS), the synergies that result from implementing NBS with traditional urban drainage systems were identified and assessed. Based on a comprehensive framework, for both wastewater and stormwater, the relevant opportunities for rethinking UDS and NBS were identified. Most relevant positive effects go beyond the mitigation of existing intrinsic constraints of traditional systems (e.g., dealing with the control of pollutants or stormwater management) since NBS also provide important economic, social, and environmental co-benefits by including water in urban planning and providing greener open spaces. This integrated and complementary solution not only represents a contribution to the sustainable management of urban water, but also enables an increase in the resilience of urban areas and, in particular, water services against climate change and for additional social co-benefits.

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.

Lignocellulosic biomass represents one of the most available renewable resources on the planet. Among the lignocellulosic biomasses, brewer’s spent grains - a byproduct of the brewing industry - has received increased interest in the last years as a way in which industries become more efficient and embrace the circular economy concept. Gasification has been cementing a solid position as an important route to convert biomass and waste materials to useful gas products. Moreover, its environmental performance is one of the greatest strengths of this technology being identified as a possible solution to meet the strict environmental regulations applied around the world. This thesis deals with biomass gasification in the Portuguese scenario, in particular BSG, in order to promote the principles of sustainability and circular economy. The main goals of the present work are the development of knowledge on the forestry and agricultural biomass species dominant in Portugal appropriate for gasification, and to assess the most suitable applications for the synthesis gas obtained from the gasification of different biomasses through experimental and numerical methods. The current status and prospects for biomass in Portugal are reviewed highlighting the gasification technology. The gasification modified equilibrium models are reviewed clarifying the different designations in order to open the possibilities of novel developments. BSG are characterized and preprocessed prior to the steam gasification in an allothermal batch gasifier. BSG gasification in a pilot-scale downdraft gasifier coupled to a motor-generator group is also performed. A modified thermodynamic equilibrium model of the downdraft gasification is developed in order to assess the potential applications of the main Portuguese biomasses through produced gas quality indices. The BSG characterization through proximate, ultimate, and thermogravimetric analysis and van Krevelen diagram reveal similar characteristics of regular lignocellulosic biomasses. The good quality of produced gas obtained from steam gasification along with the high process efficiencies attained allow the brewers to embrace the circular economy concept. From the comparative study of the main Portuguese biomasses through produced gas quality indices, one could conclude that using air as a gasifying agent in biomass gasification only provides a produced gas with enough quality to be used for energy production in boilers and turbines. A biomassa lenho-celulósica representa um dos recursos renováveis mais disponíveis no planeta. Entre as biomassas lenho-celulósicas, a dreche - um subproduto da indústria cervejeira – tem-se destacado como um meio para as indústrias cervejeiras se tornarem mais eficientes e abraçarem o conceito da economia circular. A gaseificação tem vindo a consolidar uma posição importante na conversão de biomassa e resíduos em produtos úteis sendo apontada como alternativa para atender aos exigentes regulamentos ambientais devido o seu superior desempenho ambiental. Esta tese trata da gaseificação de biomassa no cenário português, em particular da dreche cervejeira, de forma a promover os princípios da sustentabilidade e da economia circular. Os principais objetivos deste trabalho são o desenvolvimento de conhecimentos sobre as espécies de biomassa dominantes em Portugal mais adequadas à gaseificação e a avaliação das aplicações do gás de síntese obtido através de métodos experimentais e numéricos. Os recursos de biomassa em Portugal são revistos para identificar as biomassas de maior potencial para a gaseificação. Os modelos de equilíbrio termodinâmico da gaseificação são revistos para o esclarecimento das diferentes designações dos modelos e potenciar o desenvolvimento de novos modelos. A dreche cervejeira é caracterizada e pré-processada antes de ser gaseificada com vapor de água num gaseificador alotérmico laboratorial. A gaseificação da dreche cervejeira com ar atmosférico é realizada num gaseificador em co-corrente acoplado a um grupo motorgerador. É desenvolvido um modelo de equilíbrio termodinâmico modificado da gaseificação de forma a avaliar as potenciais aplicações das principais biomassas portuguesas através de índices de qualidade dos gases produzidos. As análises aproximada, elementar e termogravimétrica da dreche cervejeira revelaram características semelhantes às biomassas lenho-celulósicas comuns. A boa qualidade do gás produzido obtido da gaseificação com vapor de água, juntamente com a elevada eficiência do processo, permite aos produtores de cerveja adotarem o conceito de economia circular nas suas empresas. O estudo numérico da gaseificação das principais biomassas portuguesas permite concluir que a utilização do ar atmosférico como agente de gaseificação proporciona um gás produzido com qualidade suficiente para ser utilizado na produção de energia em caldeiras e turbinas. Fundação para a Ciência e a Tecnologia (FCT) - FRH/BD/91894/2012 Tese de doutoramento em Mechanical Engineering

Materials sustainability is becoming increasingly relevant in every developed technology and, consequently, environmentally friendly solid polymer electrolytes (SPEs) based on gellan gum and different quantities of ionic liquid (IL) 1-ethyl-3-methyl-imidazolium-thiocyanate [Emim][SCN] have been prepared and applied in electrochromic devices (ECDs). The addition of the IL does not affect the crystalline phase of gellan gum, and the samples show a compact morphology, surface uniformity, no phase separation, and good distribution of the IL within the carrageenan matrix. The developed SPE are thermally stable up to ∼100 °C and show suitable mechanical properties. The most concentrated sample (39 wt % IL content) reaches a maximum ionic conductivity value of 6.0 × 10-3 S cm-1 and 1.8 × 10-2 S cm-1 at 30 and 90 °C, respectively. The electrochromic device (ECD) was fabricated with poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) as working electrode and the developed SPE was compared with an aqueous 0.1 M KNO3 solution. The electrochromic performance of the electrolyte was assessed in terms of spectroelectrochemistry, demonstrating a fully flexible ECD operating at voltages below 1.0 V. This novel electrolyte opens the door to the preparation of high performance sustainable ECD.

Climate change has been acknowledged as one of the most significant current threats for younger generations. However, few studies have focused on climate change impacts on youth and how they can be supported. The purpose of this systematic review is to emphasize that a developmental perspective is fundamental within the interdisciplinary studies concerning climate change. Specifically, we focus our research on how the Positive Youth Development framework may inform future approaches to promote adolescents' and young adults' well-being and engagement in the context of climate change. A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search comprised two databases, and a total of 13 articles were finally considered eligible for review. Data were analyzed using a narrative method. The results show that the Positive Youth Development theory is not yet directly embedded in existing studies concerning adolescents and young adults in the context of climate change, but some of its principles were identified. Examples are provided of how Positive Youth Development characteristics and constructs can enhance future research, practice, and policies. We highlight this framework as an innovative and promising approach in the context of climate change.

The concepts of poverty have been changing over time, influenced by social, technological, economic, and cultural changes and evolutions. In this context, the concept of energy poverty has been emerging in the economic and social scenario, especially since this new millennium. Just as it is difficult to define the concept of poverty in a more global way, the same is true for the concept of energy poverty, which presents several versions, formulations and metrics for its definition and measurement. Much has been discussed about how to define and quantify energy poverty, whether on a local sampling scale or on a global scale. This difficulty is mainly due to the great geographical, economic and social disparity to which humanity is exposed. In this work we seek to evaluate the current stage of energy poverty in Brazil, taking into account that Brazil is a country with an emerging economy, and that internally it presents a great geographic and cultural diversity, which imprints specific characteristics of energy generation and use, associated with all of this, the fulfillment of the basic needs of this heterogeneous population. To this end, we intend to analyze the Brazilian energy system, through the scenario modeling method, using the LEAP (Long-range Energy Alternatives Planning) program. Using this method, historical data is validated and a base scenario is arrived at, from which two scenarios are generated: the reference scenario, in which the historical trend observed until the date in question is maintained; and the mitigation scenario, in which the intention is to identify and propose actions that can help improve the level of energy poverty by the year 2030, whether in the scope of generation or in the scope of efficiency. Although in Brazil, the definition of Energy Poverty is a relatively new concept, some actions, especially in the governmental sphere, such as the "Light for All Project" and the social tariffs have already been implemented with the intention of better meeting the most immediate needs and the energy demands of the needy population. With these actions, it is sought to promote the economic and social development of these communities, enabling an improvement in the quality of life of these citizens. Through an integrated vision concerning poverty and energy, we try to evaluate the benefits of investing in the eradication of energy poverty as a priority way to also help eradicate classic/integrated/basic poverty. The latter is more entrenched in society. Os conceitos de pobreza vêm mudando ao longo do tempo, influenciados por mudanças e evoluções sociais, tecnológicas, econômicas e culturais. Neste contexto, o conceito de pobreza energética vem despontando no cenário econômico e social, principalmente a partir desse novo milênio, e assim como é difícil de se definir o conceito de pobreza de uma forma mais global, o mesmo se passa com o conceito de pobreza energética, que apresenta várias versões, formulações e métricas para a sua definição e medição. Muito se tem discutido sobre os meios de se definir e quantificar a pobreza energética, seja numa escala de amostragem local, seja numa escala mundial, dificuldade essa, que passa principalmente pela grande disparidade geográfica, econômica e social, à qual a humanidade está exposta. Neste trabalho, procura-se avaliar o atual estágio de pobreza energética no Brasil, tendo em conta tratar-se de um país de economia emergente, que, internamente, apresenta uma grande diversidade geográfica e cultural, que imprime características específicas de geração e utilização da energia, associando a tudo isso o atendimento das necessidades básicas dessa população tão heterogênea. Para tanto, pretende-se fazer uma análise do sistema energético brasileiro pelo método de modelagem de cenários, utilizando-se do programa LEAP (Low Emission Analysis Platform). Por esse método, a partir de dados históricos geram-se três cenários: cenário de referência, no qual se mantem a tendência histórica observada até a data em questão; e dois cenários alternativos, onde pretende-se identificar e propor ações que possam ajudar a melhorar o nível de pobreza energética até o ano de 2050, seja no âmbito da geração, seja no âmbito da eficiência. Apesar de no Brasil a definição de Pobreza Energética ser um conceito relativamente novo, algumas ações principalmente no âmbito governamental, tais como o “Projeto Luz Para Todos” e as tarifas sociais já vinham sendo implementadas, com o intuito de melhor atender as necessidades mais imediatas e as demandas de energia da população mais carente. Com essas ações, busca-se promover o desenvolvimento econômico e social dessas comunidades possibilitando uma melhoria na qualidade de vida desses cidadãos. Através de uma visão integrada no que concerne à pobreza e a energia, tentar avaliar os benefícios de se investir na erradicação da pobreza energética como uma forma prioritária de também ajudar a erradicar a pobreza clássica/integrada/básica, esta mais arraigada na sociedade. Dissertação de mestrado em Economia Social