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Repositório Científico do Laboratório Nacional de Energia e Geologia

 

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O Repositório Científico do LNEG destina-se a preservar, divulgar e dar acesso à produção científica do LNEG em formato digital.

Constituem objetivos do Repositório: aumentar a visibilidade e o impacto da investigação desenvolvida no LNEG, melhorar a comunicação interna e externa e preservar a memória intelectual da instituição.

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Entradas recentes

Geochemical comparison of circular plutonic complexes with extrusive rocks from Sal Island (Cape Verde)
Publication . Garcia-Rodriguez, Maria; Villaseca, Carlos; Ignacio, Cristina; Orejana, David; Mata, João; Caldeira, Rita
ABSTRACT: Sal island is located in the northeast and is the oldest of the Cape Verde archipelago, with magmatic activity starting ~25 Ma ago. It presents a series of circular plutons that could represent the subvolcanic roots of the exposed extrusive rocks. In this work we compare the geochemical characteristics of melagabbro-gabbro of circular (~16.3 Ma) intrusions in the Old Eruptive Complex, with basaltic and nephelinitic lavas of equivalent age (~15.8 and 14.2 Ma, Torres et al., 2010). This comparison allows observing a geochemical overlap between basalts and gabbros, and the similarity between trends of part of the samples in Harker-type diagrams and REE patterns. However, this compositional overlap is incomplete, with considerable differences and absence of fractionated (intermediate) lava types related to these terms of the circular complexes. This partial but incomplete overlap of the compositional fields of the plutonic and volcanic trends argues against the possibility of a direct genetic relationship between the two.
2024-07Documento de conferência Acesso aberto Ver mais
Industrial Off-Gas Fermentation for Acetic Acid Production: A Carbon Footprint Assessment in the Context of Energy Transition
Publication . Pacheco, Marta; Brac de la Perrière, Adrien; Moura, Patrícia; silva, carla
ABSTRACT: Most industrial processes depend on heat, electricity, demineralized water, and chemical inputs, which themselves are produced through energy- and resource-intensive industrial activities. In this work, acetic acid (AA) production from syngas (CO, CO2, and H2) fermentation is explored and compared against a thermochemical fossil benchmark and other thermochemical/biological processes across four main Key Performance Indicators (KPI)—electricity use, heat use, water consumption, and carbon footprint (CF)—for the years 2023 and 2050 in Portugal and France. CF was evaluated through transparent and public inventories for all the processes involved in chemical production and utilities. Spreadsheet-traceable matrices for hotspot identification were also developed. The fossil benchmark, with all the necessary cascade processes, was 0.64 kg CO2-eq/kg AA, 1.53 kWh/kg AA, 22.02 MJ/kg AA, and 1.62 L water/kg AA for the Portuguese 2023 energy mix, with a reduction of 162% of the CO2-eq in the 2050 energy transition context. The results demonstrated that industrial practices would benefit greatly from the transition from fossil to renewable energy and from more sustainable chemical sources. For carbon-intensive sectors like steel or cement, the acetogenic syngas fermentation appears as a scalable bridge technology, converting the flue gas waste stream into marketable products and accelerating the transition towards a circular economy.
2025-07Artigo científico Acesso aberto Ver mais
Development of a georeferenced database as a tool to improve circular material flows in lignocellulosic waste valorization [Poster]
Publication . Silva, Tiago; Eusebio, Ana; Camocho, David; Alexandre, Jorge; Sousa Rocha, Cristina; Patinha, Pedro; Quental, Lídia; Gírio, Francisco; Moura, Patrícia
ABSTRACT: The Frontsh1p project aims to accelerate the development and implementation of cross-sector circular value chains through the creation of a multi-level toolkit that includes georeferenced data. This will facilitate the identification of the different stakeholders, their levels of interaction, regional distribution, and communication pathways, as well as the planning of new circular material flows for by-products and waste streams. The region of Łódzkie in Poland was selected for the development of this toolkit to establish guidelines, methodologies and technologies, based on information at the regional economic level, that can be easily replicated in different regions across Europe.
2024-10Póster em conferência Acesso aberto Ver mais
Bio-oil from hydrothermal liquefaction of microalgae cultivated in wastewater: An economic and life cycle approach
Publication . Silva, Thiago; Junior, Maurino Magno de Jesus; Magalhães, Iara; Ananias, Marina Stefany; Saleme Aona de Paula Pereira, Alexia; Rodrigues, Fábio de Ávila; Delgado dos Reis, Alberto José; Calijuri, Maria Lucia
ABSTRACT: 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.
2025-06Artigo científico Acesso aberto Ver mais
Strawberry Tree Fruit Residue as Carbon Source Towards Sustainable Fuel Biodesulfurization by Gordonia alkanivorans Strain 1B
Publication . Paixão, Susana M.; Silva, Tiago; Salgado, Francisco; Alves, Luís
ABSTRACT: Biodesulfurization (BDS) is a clean technology that uses microorganisms to efficiently remove sulfur from recalcitrant organosulfur compounds present in fuels (fossil fuels or new-generation fuels resulting from pyrolysis and hydrothermal liquefaction). One of the limitations of this technology is the low desulfurization rates. These result in the need for greater amounts of biocatalyst and lead to increased production costs. To mitigate this issue, several approaches have been pursued, such as the use of alternative carbon sources (C-sources) from agro-industrial waste streams or the co-production of high-added-value products by microorganisms. The main goal of this work is to assess the potential of strawberry tree fruit residue (STFr) as an alternative C-source for a BDS biorefinery using Gordonia alkanivorans strain 1B, a well-known desulfurizing bacterium with high biotechnological potential. Hence, the first step was to produce sugar-rich liquor from the STFr and employ it in shake-flask assays to evaluate the influence of different pretreatments (treatments with 1-4% activated charcoal for prior phenolics removal) on metabolic parameters and BDS rates. Afterwards, the liquor was used as the C-source in chemostat assays, compared to commercial sugars, to develop and optimize the use of STFr-liquor as a viable C-source towards cost-effective biocatalyst production. Moreover, the high-market-value bioproducts simultaneously produced during microbial growth were also evaluated. In this context, the best results, considering both the production of biocatalysts with BDS activity and simultaneous bioproduct production (carotenoids and gordofactin biosurfactant/bioemulsifier) were achieved when strain 1B was cultivated in a chemostat with untreated STFr-liquor (5.4 g/L fructose + glucose, 6:4 ratio) as the C-source and in a sulfur-free mineral-minimized culture medium at a dilution rate of 0.04 h-1. Cells from this steady-state culture (STFr L1) achieved the highest desulfurization with 250 mM of dibenzothiophene as a reference organosulfur compound, producing a maximum of approximate to 213 mM of 2-hydroxibyphenil (2-HBP) with a corresponding specific rate (q2-HBP) of 6.50 mu mol/g(DCW)/h (where DCW = dry cell weight). This demonstrates the potential of STFr as a sustainable alternative C-source for the production of cost-effective biocatalysts without compromising BDS ability. Additionally, cells grown in STFr L1 also presented the highest production of added-value products (338 +/- 15 mu g/g(DCW) of carotenoids and 8 U/mL of gordofactin). These results open prospects for a future G. alkanivorans strain 1B biorefinery that integrates BDS, waste valorization, and the production of added-value products, contributing to the global economic viability of a BDS process and making BDS scale-up a reality in the near future.
2025-05Artigo científico Acesso aberto Ver mais