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Zeolitas e minerais associados como indicadores de alteração hidrotermal pós-magmática em basaltos toleíticos mesozoicos no Nordeste do Brasil
No full textABSTRACT: In northeastern Brazil, tholeiitic basalts and microgabbros from the Rio Ceará-Mirim dike swarm and Serra do Cuó basaltic flow experienced post-magmatic hydrothermal alteration, forming secondary minerals that replaced magmatic phases and filled amygdules. Petrographic, X-ray diffraction, thermogravimetric, and chemical analyses identified laumontite, quartz, and calcite as the dominant amygdule minerals in the Rio Ceará-Mirim dikes, formed at temperatures < 150 °C (Stage II) following an earlier low to moderate-temperature (< 150 – 200 ºC) alteration phase (Stage I). In the Serra do Cuó basalts, polymineralic amygdule formation began with mafic phyllosilicates (from < 150 to ~200 °C, Stage I) and proceeded to Ca-Na zeolites (~250 °C, Stage II). These assemblages reflect fluid composition changes due to primary mineral destabilization by heated meteoric fluids. Results indicate fluid composition, rather than temperature, as the primary control on mineral variability, highlighting the role of host-rock chemistry in hydrothermal alteration.RESUMO: No nordeste do Brasil, basaltos toleíticos e microgabros do enxame de diques Rio Ceará-Mirim e do derrame basáltico Serra do Cuó passaram por alteração hidrotermal pós-magmática, resultando na formação de minerais secundários que substituíram fases magmáticas e preencheram amígdalas. Análises petrográficas, difracção de raios X, análises termogravimétricas e químicas identificaram laumontite, quartzo e calcite como os principais minerais nas amígdalas dos diques Rio Ceará-Mirim, formados a temperaturas < 150 °C (Estágio II), após uma fase prévia de alteração a temperaturas baixas a moderadas (< 150 – 200 °C Estágio I). Nos basaltos Serra do Cuó, a formação de amígdalas poliminerálicas iniciou-se com filossilicatos máficos (de temperaturas < 150 °C até ~200 °C, Estágio I), e prosseguiu com zeolitas cálcio-sódicas (~250 °C, Estágio II). Estas associações refletem mudanças na composição dos fluidos, decorrentes da destabilização dos minerais primários por fluidos meteóricos aquecidos. Os resultados indicam que a composição do fluido, mais do que a temperatura, é o principal fator controlador da variabilidade mineral, sublinhando o papel da química da rocha hospedeira na alteração hidrotermal
The fusion of geosite inventories as a geoconservation strategy in Portugal
No full textRESUMO: A unificação dos dois principais inventários de geossítios desenvolvidos em Portugal (LNEG e Universidade do Minho) é importante para a comunidade geológica portuguesa, para o ordenamento do território e para procedimentos de conservação da natureza. Este trabalho visa reforçar a necessidade de prosseguir os esforços para uma estratégia de geoconservação em Portugal, salientando a necessidade de proteção do património geológico português e o seu reconhecimento junto das instituições oficiais de conservação da natureza. É apresentada a metodologia desenvolvida para a fusão dos inventários, com destaque para a definição dos campos de informação.ABSTRACT: The unification of the two main geosites inventories developed in Portugal (University of Minho and LNEG) is important for the Portuguese geological community, for land use planning and nature conservation procedures. This task aims to reinforce the need of continuing the efforts for a geoconservation strategy in Portugal, stressing the need of the protection of the Portuguese geoheritage and its recognition within the official nature conservation institutions. In this work, the methodological setup of the inventories’ fusion is presented, with emphasis on the definition of the dataset fields
Addressing rising energy needs of megacities : case study of Greater Cairo
No full textABSTRACT: Urban energy system modelling allows megacities to assess their future development and to draw sustainable pathways to meet the rapidly increasing energy needs. This paper elaborates three different scenarios for energy transition in Greater Cairo with particular emphasis on the impact of lowering the share of inhabitants living in informal settlements. A city-specific TIMES energy system model is used to investigate how energy supply and demand will evolve between 2015 and 2050. Besides, the impacts in final
energy consumption and CO2 emissions are investigated considering different socio-economic pathways.
The scenarios show that the long-term cost-efficiency optimization leads to the decarbonization of the
power sector even in the absence of climate constraints. Climate policies are modeled to achieve by 2050 a carbon emissions reduction of 50% below the 2015 baseline. The results indicate that the implementation
of current urban plans will double the carbon emissions per capita if no mitigation policies are adopted. The urban expansion programs need to take into consideration the energy-environment economic nexus and to be coupled with climate mitigation policies to contain the rising carbon emissions.info:eu-repo/semantics/publishedVersio
Technological innovations in decarbonisation strategies: a text-mining approach to technological readiness and potential
No full textABSTRACT: This study presents a novel, multifaceted approach to evaluating decarbonisation technologies by integrating advanced text-mining tools with comprehensive data analysis. The analysis of scientific documents (2011-2021) and mapping 368 technologies from the IEA's Energy Technology Perspectives identified 41 technology domains, including 20 with the highest relevance and occurrence. Domain readiness was assessed using mean Technology Readiness Levels (TRLs) and linked to six decarbonisation pathways. The "Electrification of uses" pathway ranked highest, demonstrating significant CO2 mitigation potential and high readiness (mean TRL 7.4, with two-thirds of technologies scoring over 7) despite challenges in hard-to-electrify sectors. The findings provide actionable insights for policymakers, highlighting the need for pathway-specific strategies, a deeper understanding of synergies between pathways, and balancing innovation with deployment to accelerate decarbonisation.info:eu-repo/semantics/publishedVersio
Hybrid Variable Renewable Power Plants: A Case Study of ROR Hydro Arbitrage
No full textABSTRACT: Wind and solar energy sources, while sustainable, are inherently variable in their power generation, posing challenges to grid stability due to their non-dispatchable nature. To address this issue, this study explores the synergistic optimization of wind and solar photovoltaic resources to mitigate power output variability, reducing the strain on local grids and lessening the reliance on balancing power in high-penetration renewable energy systems. This critical role of providing stability can be effectively fulfilled by run-of-river hydropower plants, which can complement fluctuations without compromising their standard operational capabilities. In this research, we employ a straightforward energy balance model to analyze the feasibility of a 100 MW virtual hybrid power plant, focusing on the northern region of Portugal as a case study. Leveraging actual consumption and conceptual production data, our investigation identifies a specific run-of-river plant that aligns with the proposed strategy, demonstrating the practical applicability of this approach
Exploring Marine Biomineralization on the Al-Mg Alloy as a Natural Process for In Situ LDH Growth to Improve Corrosion Resistance
No full textABSTRACT: This study provides a detailed characterization of the AA5083 aluminum alloy, surface, and interface over 6 months of immersion in seawater, employing techniques such as SEM/EDX, GIXRD, mu-Raman and XPS. The purpose was to evaluate the evolution of the biomineralization process that occurs on the Al-Mg alloy. By investigating the specific conditions that favor the in situ growth of layered double hydroxide (LDH) during seawater immersion as a result of biomineralization, this research provides insights into marine biomineralization, highlighting its potential as an innovative and sustainable strategy for corrosion protection
Descarbonizar micro/mini-redes através da complementaridade da produção solar fotovoltaica e eólica
Get PDFRESUMO: Este trabalho apresenta uma metodologia para determinar a capacidade instalada ótima de fontes de energia renováveis variáveis no tempo, numa mini-rede selecionada, e avaliar o potencial destas tecnologias para satisfazer o consumo de eletricidade, permitindo reduzir a dependência de geradores alimentados por combustíveis fósseis. A capacidade ótima é identificada com base na exploração estratégica da sinergia eólica e solar fotovoltaica (FV) para atender à procura de eletricidade, neste caso, para substituir a produção com geradores a diesel. Para este efeito, neste trabalho, explora-se o uso de diferentes ângulos de azimute e inclinação dos sistemas solares fotovoltaicos fixos (convencionais e bifaciais), bem como sistemas com seguimento para criar um portfólio de geração ideal. Os resultados preliminares obtidos destacam que é necessário diversificar a orientação dos painéis solares e explorar a energia eólica para evitar vários períodos com excesso de produção e, consequentemente, corte de geração. Apesar de ser necessário continuar a desenvolver este trabalho, os resultados mostram que o uso dos geradores a diesel pode ser significativamente reduzido, especialmente durante o período diurno.ABSTRACT: This work presents a methodology to determine the optimal share of variable renewable energy sources (vRES) in a selected mini-grid, and evaluate its ability to satisfy electricity demand, allowing to reduce dependence on generators using fossil fuel. The optimal share is identified based on the strategic exploitation of wind and solar photovoltaic (PV) synergies to meet electricity demand, in this case, to replace the production from diesel generators. To this end, in this work, the use of different azimuth and tilt angles for solar PV systems (conventional and bifacial) as well as tracking systems to create an ideal mix is explored. The preliminary results obtained highlight that it is necessary to diversify the orientation of solar panels and explore wind energy to avoid several periods of generation outages. Although it is necessary to continue developing this work, the results show that the use of diesel generators can be significantly reduced, especially during the day.N/
Systematic and Bibliometric Review of Biomethane Production from Biomass-Based Residues: Technologies, Economics and Environmental Impact
No full textABSTRACT: Fossil fuels drive global warming, necessitating renewable alternatives such as biomethane (or renewable natural gas). Biomethane, primarily produced through anaerobic digestion (AD), offers a cleaner energy solution but is limited by the slow AD process. Biomass gasification followed by syngas methanation has emerged as a faster alternative. This review examines advancements in these processes over the last decade (2015–2024), focusing on techno-economic and life cycle assessment (LCA) studies. Techno-economic analyses reveal that biomethane production costs are influenced by several factors, including process complexity, feedstock type and the scale of production. Smaller gasification units tend to exhibit higher capital costs (CAPEX) per MW capacity, while feedstock choice and process efficiency play significant roles in determining overall production costs. LCA studies highlight higher impacts for gasification and methanation due to energy demands and associated emissions. However, integrating renewable hydrogen production through electrolysis, along with innovations such as sorption-enhanced gasification (SEG), can enhance overall system efficiency and reduce environmental impacts. This review critically evaluates the technical and economic challenges, along with the opportunities for optimizing biomethane production, and discusses the potential for these technologies to contribute to sustainable bioenergy solutions in the transition to a low-carbon economy.info:eu-repo/semantics/publishedVersio
Lithium Role in the Clean Energy Transition: Challenges and Prospects [Comunicação oral]
No full textThermal Stability and Irradiation Resistance of (CrFeTiTa)70W30 and VFeTiTaW High Entropy Alloys
No full textABSTRACT: Nuclear fusion is a promising energy source. The International Thermonuclear Experimental Reactor aims to study the feasibility of tokamak-type reactors and test technologies and materials for commercial use. One major challenge is developing materials for the reactor's divertor, which supports high thermal flux. Tungsten was chosen as the plasma-facing material, while a CuCrZr alloy will be used in the cooling pipes. However, the gradient between the working temperatures of these materials requires the use of a thermal barrier interlayer between them. To this end, refractory high-entropy (CrFeTiTa)70W30 and VFeTiTaW alloys were prepared by mechanical alloying and sintering, and their thermal and irradiation resistance was evaluated. Both alloys showed phase growth after annealing at 1100 degrees C for 8 days, being more pronounced for higher temperatures (1300 degrees C and 1500 degrees C). The VFeTiTaW alloy presented greater phase growth, suggesting lower microstructural stability, however, no new phases were formed. Both (as-sintered) alloys were irradiated with Ar+ (150 keV) with a fluence of 2.4 x 1020 at/m2, as well as He+ (10 keV) and D+ (5 keV) both with a fluence of 5 x 1021 at/m2. The morphology of the surface of both samples was analyzed before and after irradiation showing no severe morphologic changes, indicating high irradiation resistance. Additionally, the VFeTiTaW alloy presented a lower deuterium retention (8.58%) when compared to (CrFeTiTa)70W30 alloy (14.41%)