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Bio-oil from hydrothermal liquefaction of microalgae cultivated in wastewater: An economic and life cycle approach
No full textABSTRACT: Although microalgae are a promising sustainable biofuel feedstock, their energy-intensive production and most environmental assessments rarely achieve the desired trade-off between productivity and sustainability. In this context, this study aims to evaluate the economic and environmental feasibility of producing bio-oil via hydrothermal liquefaction (HTL) of wastewater-grown microalgae at an industrial scale. Four scenarios varied production scale and steam source: sugarcane bagasse (SCB) in SC1 and SC3, liquefied petroleum gas (LPG) in SC2 and SC4. Each scenario processed microalgae at 300 degrees C for 30 min. Smaller-scale feedstock (1332.9 kg/h) in SC1 and SC2 produced 34.6 kg/h of bio-oil, while the larger feedstock (85,554.4 kg/h) in SC3 and SC4 yielded 2222.2 kg/h. Microalgae biomass cultivation costs dominated overall expenses (56-75 %). Economic analyses indicated minimum selling prices of 3.82-8.52 USD/kg, exceeding the average literature figure of 1.57 USD/kg. Life Cycle Assessment (LCA) showed SCB reduced fossil resource depletion by 14.97 % compared to LPG but increased emissions of nitrogen oxides, particulates, and toxic compounds, which are manageable via selective catalytic reduction and flue gas desulphurization. Cyclohexane as a solvent elevated human carcinogenic toxicity, greener alternatives could reduce toxicity but may cost more, requiring further cost analysis. Advancing this biorefinery route requires optimization of cultivation and processing costs, adoption of environmentally benign solvents, and implementation of emission control strategies to enable economically feasible and environmentally sustainable bio-oil production
Contribution to the development of a new value chain in the marine renewable energy sector
No full textABSTRACT: As part of the commitments made in the NECP2030 for Portugal, an increase in wind capacity is planned, including an additional 10.4 GW onshore and 2 GW offshore. In this sense, it is necessary to assess the conditions for the creation of a new industrial value chain that will accelerate this development and offer attractive conditions for the involvement of the industrial sector, providing conditions for the objectives recommended in the NECP 2030 to be met. Projects OffshorePlan - Planning for the Use of Offshore Renewable Energies in Portugal, and OceanTrans - Ocean energy technologies transformative potential analyzed the relevant socio-economic component for this sector, namely the process of creating a new industrial value chain to support the development of marine renewable energies. As part of this research, a questionnaire survey was conducted targeting companies in sectors with complementary skills and resources, directly or indirectly related to the development of projects in this area. The questionnaire yielded 114 responses from companies already active and 182 from companies willing to become involved in the future. The results allowed us to obtain a global view of the actual and potential involvement of the industrial sector, as well as to gain some insight into how companies view the requirements to operate in this area and the main barriers to their performance. This article presents the main findings obtained in the scope of this research and discusses their contribution to the advancement of the marine renewable energy sector and, as such, to the development of offshore wind energy in Portugal.COST Action CA20109 Modenerlands, supported by COST (European Cooperation in Science and Technology
Contribution of municipalities on the promotion of geodiversity: the example of the Geovaldevez initiative
No full textRESUMO: O conceito de geodiversidade tem vindo a ganhar lentamente reconhecimento social. Os municípios podem desempenhar um papel importante na sensibilização das suas comunidades e dos turistas para a importância da geodiversidade. O município de Arcos de Valdevez, no Norte de Portugal, desenvolveu uma iniciativa para a promoção educativa e turística da geodiversidade local. Esta iniciativa inclui publicações, interpretação geológica de percursos pedestres, um kit educativo para professores, um sítio Web e uma aplicação específicos e um centro interpretativo onde os visitantes podem usufruir de dispositivos 3D e interativos para visualizar a geodiversidade do município.ABSTRACT: The geodiversity concept is slowly gaining social recognition. Municipalities can play an important role in raising the awareness of their communities and tourists about the importance of geodiversity. Arcos de Valdevez municipality in Northern Portugal has developed an initiative for the educative and touristic promotion of the local geodiversity. This initiative includes publications, geological interpretation of trails, an educative kit for teachers, a dedicated website and app, and an interpretative centre where visitors can enjoy 3D and interactive devices to visualize the municipality geodiversity
(RE)crystallization or (NEO)crystallization. Concepts in textbooks of Biology and Geology 11th grade
No full textRESUMO: O metamorfismo, temática incluída nas aprendizagens essenciais da disciplina de Biologia e Geologia do 11.° ano, é entendido como um conjunto de processos geológicos que envolvem modificações no conteúdo/composição mineral e/ou microestruturais de uma rocha, predominantemente no estado sólido. Durante esses processos podem ocorrer a nucleação e o crescimento de novos minerais - neocristalização - e de fases minerais já presentes - recristalização. Esta distinção leva-nos a questionar como é que esta temática é apresentada nos manuais escolares portugueses de Geologia. Para tal, foram analisados três manuais escolares do ano letivo 2022/23 e três do ano letivo 2008/09. Verificou-se que os manuais de 2008/09 referem apenas o processo de “recristalização”. Constatando-se uma evolução positiva nos manuais escolares de 2022/23, mas apenas um introduz o conceito de “neocristalização”. Ainda assim, no geral, estes promovem uma melhor compreensão dos processos que levam à formação de rochas metamórficas.ABSTRACT: In Portugal, metamorphism is a topic included in the learnings of the 11th grade discipline of Biology and Geology. It is understood as a set of processes involving modifications in the mineral content/composition and/or microstructural of a rock, predominantly in the solid state. During these processes both nucleation and growth of new minerals - neocrystallization - and of mineral phases already present - recrystallization - may occur. This distinction leads us to question how this topic is presented in the Portuguese school textbooks of Geology. For that, three textbooks from the school year of 2022/23 and other three from the school year of 2008/09
were object of analysis. Despite the positive evolution noted in the 2022/23 textbooks, only one introduces the concept of “neocrystallization”. Nevertheless, the 2022/23 textbooks promote a better understanding of the processes that lead to the formation of metamorphic rocks
Requisitos para a seleção de locais para o armazenamento geológico de hidrogénio em aquíferos salinos
No full textABSTRACT: Underground hydrogen storage (UHS) in deep saline aquifers is a promising solution for large-scale, long-duration energy storage, vital for addressing renewable intermittency and enabling deep decarbonization. This study presents a benchmarking of requirements and a comprehensive framework for site screening of saline aquifers for hydrogen storage. It integrates technical parameters –such as reservoir quality, seal integrity, and geomechanical stability–with non-technical aspects, including economic viability, regulatory readiness, environmental risk, and social acceptance. Particular focus is given to hydrogen-specific challenges affecting storage integrity, especially geochemical and geomechanical factors. Drawing from experience with natural gas and CO2 storage, the study proposes a multidisciplinary screening workflow to support early-stage project assessment. The findings provide a foundation for future pilot projects, policy development, and regulatory frameworks tailored to UHS in porous media, contributing to the strategic expansion of hydrogen infrastructure and energy system resilience.RESUMO: O armazenamento subterrâneo de hidrogénio (ASH) em aquíferos salinos profundos representa uma solução promissora para o armazenamento de energia em grande escala e de longa duração, essencial para lidar com a intermitência das renováveis e permitir uma descarbonização profunda. Este estudo apresenta uma análise comparativa dos requisitos e um quadro abrangente para a seleção de locais adequados ao armazenamento de hidrogénio em aquíferos salinos. Integra parâmetros técnicos – como a qualidade do reservatório, a integridade da camada selante e a estabilidade geomecânica – com aspetos não técnicos, incluindo viabilidade económica, preparação regulatória, riscos ambientais e aceitação social. Dá-se especial atenção aos desafios específicos do hidrogénio que afetam a integridade do armazenamento, nomeadamente fatores geomecânicos e geoquímicos. Com base na experiência de armazenamento de gás natural e de CO2, é proposto um fluxo de trabalho multidisciplinar para apoiar a avaliação em fases iniciais. As conclusões constituem uma base para projetos-piloto, desenvolvimento de políticas e enquadramentos regulatórios adaptados ao ASH em meios porosos, contribuindo para a expansão estratégica da infraestrutura do hidrogénio e para a resiliência do sistema energético
Strategic Bidding to Increase the Market Value of Variable Renewable Generators in Electricity Markets
No full textABSTRACT: The 2050 global ambition for a carbon-neutral society is increasing the penetration of the most competitive variable renewable technologies, onshore wind and solar PV. These technologies are known for their near-zero marginal costs but highly variable time-dependent generation. Power systems with major penetrations of variable generation need high balancing flexibility to guarantee their stability by maintaining the equilibrium between demand and supply. Electricity markets were designed for dispatchable technologies. Support schemes are used to incentivize and de-risk the investment in variable renewables, since actual market designs are riskier for their active participation. This study presents three strategic bidding strategies for the active participation of variable renewables in electricity markets based on probabilistic quantile-based forecasts. This case study examines the levels of active market participation for a wind power producer (WPP) in the Iberian electricity market and the Portuguese balancing markets, where WPPs are financially responsible for imbalances and operate without support schemes in the first and second stages of the Iberian market designs. Results from this study indicate that the WPP has the potential to increase its market value between 36% and 155% if participating in the tertiary and secondary balancing markets completely adapted to its design, respectively. However, considering the use of strategic bidding in actual market designs, by participating in the secondary reserve, the WPP can increase its market value by 10% and 45% when compared with perfect foresight and operational cases, respectively
Leaching as the first step of hydrometallurgy in the recycling of metals from end-of-life products [Comunicação oral]
No full textSoil Classification Maps for the Lower Tagus Valley Area, Portugal, Using Seismic, Geological, and Remote Sensing Data
No full textABSTRACT: The Lower Tagus Valley (LTV) region has the highest population density in Portugal, with over 3.7 million people living in the region. It has been struck in the past by several historical earthquakes, which caused significant economic and human losses. For a proper seismic hazard evaluation, the area needs detailed V-s30 and soil classification maps. Previously available maps are based on proxies, or an insufficient number of velocity measurements followed by coarse geological generalizations. The focus of this work is to significantly improve the available maps. For this purpose, more than 90 new S-wave seismic velocities measurements obtained from seismic refraction and seismic noise measurements, doubling the number used in previously available maps, are used to update available V-s30 and soil classification maps. The data points are also generalized to the available geological maps using local lithostratigraphic studies and, for the first time, satellite images of this area. The results indicate that lithological and thickness changes within each geological formation prevent a simple generalization of geophysical data interpretation based solely on geological mapping. The maps presented here are the first attempt to produce maps at a scale larger than 1:1,000,000 in Portugal, with direct shear wave velocity measurements. A tentative approach to produce more detailed maps using machine learning was also carried out, presenting promising results. This approach may be used in the future to reduce the number of shear wave measurements necessary to produce detailed maps at a finer scale
Avaliação do perigo de queda de cinzas para cenários de erupção Sub-Pliniana no vulcão do Fogo (São Miguel, Açores)
No full textABSTRACT: The geological setting of the Azores makes this region prone to volcanic eruptions. A future explosive eruption in the Azores could have a significant socioeconomic impact and affect the North Atlantic airspace. This study aims to assess tephra fallout hazard associated with an explosive eruption of Fogo volcano on the island of São Miguel. Numerical simulations of tephra deposition were performed using an advection-diffusion model and considering the most probable scenario for a future explosive eruption at Fogo, a Sub-Plinian eruption with Volcanic Explosivity Index of 4. The obtained results suggest that the eastern half of São Miguel Island could be the most affected, regardless of the season, and Furnas parish would be the locality with a thicker deposition of tephra (≥2 m). This approach based on the analysis of scenarios is crucial for decision-making by civil protection entities.RESUMO: O enquadramento geológico dos Açores torna esta região propícia à ocorrência de erupções vulcânicas. Uma futura erupção explosiva nos Açores poderá ter um impacto socioeconómico significativo e afetar o espaço aéreo do Atlântico Norte. Este estudo tem como objetivo avaliar o perigo de queda de cinzas associado a uma erupção explosiva do vulcão do Fogo na ilha de São Miguel. Foram realizadas simulações numéricas de deposição de cinzas usando um modelo de advecção-difusão e considerando o cenário mais provável para uma futura erupção explosiva no Fogo, uma
erupção Sub-Pliniana com Índice de Explosividade Vulcânica 4. Os resultados obtidos sugerem que a metade leste de São Miguel poderá ser a mais afetada, independentemente da estação do ano, sendo as Furnas a freguesia com maior deposição de cinzas (≥2 m de espessura). Esta abordagem baseada na análise de cenários é fundamental à tomada de decisão por parte das entidades de proteção civil