Repositório do LNEG

National Laboratory of Energy and Geology Scientific Repository

Welcome to LNEG’s Scientific Repository

The LNEG’s Scientific Repository intends to preserve, disseminate and give access to LNEG's scientific production in digital format.

The objectives of the Repository are: to increase the visibility and impact of the research carried out at LNEG, to improve internal and external communication and to preserve the institution's intellectual memory.

Email repositorio@lneg.pt

Recent Submissions

Systematic review on social acceptance of mining in the context of the energy transition

Publication . Santos, Elaine; Simoes, Sofia

ABSTRACT: This technical report presents a systematic review of the scientific literature on the social acceptance of mining in the context of the energy transition. The analysis covered 118 publications from 1998 to 2025 in English, Portuguese, and Spanish, integrating quantitative and qualitative methods. The results show the growth of the field (7.47% per year) and reveal the following central factors for social acceptance: community participation, transparency, procedural justice, institutional trust, and conflict management. Regional differences were identified: in Europe, the emphasis falls on governance and transparency, whereas in Latin America socio-environmental justice, conflicts, and expectations prevail. Despite the centrality of critical minerals for the energy transition, few studies explicitly articulate both themes. The report proposes recommendations for policymakers, companies, and communities, aiming at more participatory practices. This is the first LNEG study on this topic, contributing to public policies and institutional strategies in the mining sector.

2025-11Technical report

Open access

Optimizing Chlorella vulgaris production and exploring its impact on germination through microalga-N2-fixing bacteria consortia

Publication . Sanchez-Zurano, Ana; Vilaro-Cos, Silvia; Figueiredo, Daniel; Melkonyan, Lusine; Ferreira, Alice; Acien Fernandez, F. Gabriel; Lafarga, Tomás; Gouveia, Luisa

ABSTRACT: Microalgal biomass is increasingly valued in industrial and agricultural sectors due to its bioactive compounds. However, large-scale production remains costly, mainly due to nitrogen fertilizer expenses. A promising sustainable alternative is co-cultivation with N2-fixing bacteria, capable of supplying biologically available nitrogen. In this study, Chlorella vulgaris was grown in synthetic medium with and without nitrogen, as well as in co-culture with three different N2-fixing bacteria in nitrogen-free medium. Microalgal growth was assessed by dry weight, Fv/Fm ratio, and flow cytometry, which also allowed evaluation of population dynamics and cell viability. Biomass composition (proteins, carbohydrates, lipids, chlorophyll, and carotenoids) was analyzed under all conditions. Co-cultures in nitrogen-free medium showed comparable biomass productivity to nitrogen-supplemented controls, although Fv/Fm values indicated physiological stress in some cases. Moreover, the agricultural potential of the resulting biomass and supernatants was evaluated through germination bioassays using lettuce seeds. All cultures tested at 0.2 g & sdot;L-1 significantly improved the germination index. Also, applying the culture supernatant (biomass removed) also yielded positive effects, with GI increases exceeding 40 %. These results suggest that co-cultivation with N2-fixing bacteria can support efficient microalgal production while generating biomass and supernatants with biostimulant potential, contributing to sustainable agriculture and circular bioeconomy strategies.

2025-10Journal article

Open access

Determination of reflectance of interest from limited state-of-the-art solar reflector field soiling measurements

Publication . Wette, Johannes; Sutter, Florian; Cunha Diamantino, Teresa; Montecchi, Marco; Bern, Gregor; Fernández-García, Aránzazu

ABSTRACT: In concentrated solar thermal technologies, plant operators usually monitor the soiling of their solar field with handheld reflectometers. These measurements can be used for yield calculations and to adapt cleaning strategies: if the reflectometer reading falls below an empirically established threshold, the solar field should be cleaned. There are several commercial reflectometers available for this purpose, but all of them measure at different combinations of wavelength, acceptance angle or incidence angle. It is the purpose of this study to bring the readings from all main commercial reflectometers to the same representative value, enabling their comparison with one another and the translation of these readings into a meaningful reflectance parameter. Thus, different handheld reflectometers are correlated with a laboratory reflectometer, capable of measuring in the whole solar spectral region, covering a wide range of incidence and acceptance angles. The most significant parameter is the near-specular solar-weighted reflectance, measured at the typical incidence and acceptance angles for a given plant, as it is the most precise parameter to describe the reflected energy from the solar field. The correlations for all included reflectometers, show highly linear correlations over a wide range of soiling levels with low deviations. Consequently, the correlations presented herein enable the plant operators at the studied site to compute the near-specular solar-weighted reflectance from their reflectometer readings. and, with that, increase the significance of the measurements without collecting any additional data. The work also establishes a detailed procedure to derive this type of correlations at any site of interest.

2025-10Journal article

Open access

Como o trabalho do LNEG apoia a concretização do PNEC: Plano Nacional de Energia e Clima - Conheça 10 dos trabalhos do LNEG que contribuem para a concretização do PNEC

Publication . Simoes, Sofia; Simões, Teresa; Barbosa, Juliana Pacheco; Rodrigues, Carlos; Azevedo, Pedro; Cardoso, João; Facão, Jorge; Costa, Paula Silva; Justino, Paulo Alexandre; Gírio, Francisco; Reis, Alberto; Passarinho, Paula; Duarte, Luís; Moura, Patrícia; Abreu, Mariana; Estanqueiro, Ana; Couto, António; Oliveira, Paula; Quental, Lídia; Patinha, Pedro; Catarino, Justina; Picado, Ana; Ramalho, Elsa; de Oliveira, Daniel Pipa Soares; Filipe, Augusto; Albardeiro, Luís; Santos, Sara; Gonçalves, Pedro

2025-11Interactive Resource

Open access

Unprecedented U-Pb-Th SHRIMP and Lu-Hf isotopic data in zircon from Tandilia basement rocks, Argentina: new insights into Palaeoproterozoic and Neoproterozoic crustal reworking of the Rio de la Plata craton

Publication . Angeletti, Melisa; Chichorro, Martim Afonso; Castro, Antonio; Frisicale, María Cristina; Solá, A. Rita; Dimieri, Luis Vicente; Martinez, Juan Cruz

ABSTRACT: We present new geochronological zircon data from the Siempre Amigos Hill (SAH), a small but representative portion of Tandilia Terrane within the R & iacute;o de la Plata Craton (RPC). U-Pb-Th SHRIMP data indicate a heterogeneous Palaeoproterozoic (Rhyacian) crust. A garnet-bearing granite (2165 +/- 16 Ma) hosts felsic (2108 +/- 13.6 Ma) to intermediate gneiss protolith (2104 +/- 8 Ma), andesite with a sanukitoid signature (2094 +/- 47 Ma) and granulites or charnockites. Additionally, calc-alkaline granitoids (2092 +/- 13 Ma) intruded, as a result of differentiation from an igneous mafic sanukitoid source. Localised low-temperature shear zones affected the sequence. Lu-Hf isotopic data for the post-orogenic stage (< 2.1 Ga) complement previous results, showing progressive negative epsilon Hf-(t) values. These isotopes suggest post-orogenic transtension. New Neoproterozoic ages (652 +/- 37 Ma, 618.4 +/- 11.2 Ma and 686 +/- 60 Ma) from granites, with low-to-very low zircon Th/U ratios, are presented as evidence of U-Th-Pb systems overprinting by Neoproterozoic (Cryogenian) thermal-hydrothermal events. Those Neoproterozoic ages are, within analytical uncertainty, equivalent to the 656 +/- 19 Ma metamorphic age obtained for the Palaeoproterozoic granulite. These new Neoproterozoic ages, suggests a thermal perturbation linked either to the collision of the Nico Perez Terrane against the passive margin of RPC, or the Neoproterozoic evolution of the Ventania System basement during the Brasiliano/ Pan-African orogeny.

2025-11Journal article

Open access