4161 research outputs found
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Methodologies for assessing corrosion under dynamic conditions with molten salts in CSP/CST applications [Resumo]
No full textABSTRACT: Renewable energy implementation represents a key point in reversing global warming and climate change. In recent years, there has been an investment in Concentrated Solar Power (CSP) with Energy Storage (TES). Solar Salt is the most energy storage fluid optimized with a melting point of 223 °C and thermally stable up to about 550 °C. One of the most relevant problems in the use of fluids as thermal energy storage is their compatibility with construction materials (pipes, valves and tanks). This fact, combined with high temperatures (300-550 °C) makes the materials more susceptible to corrosion. Static immersion experiments are suited to screen and compare different candidate materials for molten salt applications (Fernández et al., 2019; Gomes et al. 2019), but corrosion rates derived from these experiments might differ significantly from the rates experienced in a real operating environment of a solar plant (Florian et al. 2021). There are currently no specific procedures for evaluating corrosion in molten salts under dynamic conditions, so it is important to develop more practical application conditions to validate methodologies and facilities. The main purpose of this work is to identify the suitable procedures to make a reproducible experimental dynamic corrosion test using an experimental set-up that can vary the velocity of molten salts over a wide range.N/
Valorization and Bioremediation of Digestate from Anaerobic Co-Digestion of Giant Reed (Arundo donax L.) and Cattle Wastewater Using Microalgae
No full textABSTRACT: Anaerobic digestion followed by microalgal cultivation is considered a promising renewable alternative for the production of biomethane with reduced effluent generation, thus lowering the environmental impact. In this arrangement, in addition to generating energy, the microalgae act by potentiating the refinement of the effluents generated via anaerobic digestion (digestates). In this study, the microalga Tetradesmus obliquus was cultivated in photobioreactors with the final digestate resulting from the co-digestion of Arundo donax L. plant biomass and cattle wastewater. The biotechnological route used was efficient, and the biogas production ranged from 50.20 to 94.69 mL gVS-1. The first-order kinetic model with variable dependence (FOMT) provided the best fit for the biogas production data. In the microalgal post-treatment, the removal values ranged from 81.5 to 93.8% for the chemical oxygen demand, 92.0 to 95.3% for NH4+-N, and 41.7 to 83.3% for PO43- after 26 days. The macromolecular composition of the algal biomass reached lipid contents ranging from 33.4 to 42.7%. Thus, the proposed process mediated by microalgae can be considered promising for the bioremediation and recovery of effluents produced by agriculture through the use of microalgal biomass for bioproduct production.info:eu-repo/semantics/publishedVersio
Enhancing Corrosion Resistance of Al-Mg Alloys through Biomineralization [Resumo]
No full textABSTRACT: In recent decades, new emerging microbiological technologies have been studied, based on the recognition that microorganisms can inhibit corrosion by different mechanisms, the so-called MICI (microbiologically influenced corrosion inhibition), opening up different lines of research. In this context, biomineralization has been attracting the attention of researchers, with an increasing number of studies showing that different types of mineralized layers formed on metal surfaces can reduce the risk of corrosion
Opportunities and Constraints of the Adsorption of Rare Earth Elements onto Pyrolytic Carbon-Based Materials: A Mini-Review
No full textABSTRACT: Rare earth elements (REEs), comprising seventeen metallic elements, including lanthanides, scandium, and yttrium, are indispensable for modern technological industries due to their unique properties. However, their supply is critically risky for the European Union, with 95% of global production concentrated in China, Brazil, Vietnam, Russia, India, and Australia. This mini-review examines the adsorption of REEs onto pyrolytic carbon-based materials as a sustainable recovery method from secondary raw materials. The review covers different types of carbon-based adsorbents used in several research works, such as activated carbon, chars, and biochar, and discusses their adsorption mechanisms and influencing factors. Comparative analyses of adsorption capacities highlight the significance of surface area and functionalization in enhancing adsorption efficiency. Despite promising results, the variability in adsorption performance due to experimental conditions and the scarcity of real-world application studies are noticed. This review underscores the need for further research using real e-waste leachates to validate the practical applicability of pyrolytic carbon-based adsorbents for REEs' recovery, aiming for an economically and environmentally sustainable solution.info:eu-repo/semantics/publishedVersio
Recommendations for market trading in a ~100% power system : Deliverable D6.5
No full textProject TradeRES - New Markets Design & Models for 100% Renewable Power SystemsN/
Panorama das estratégias de circularidade na energia eólica e solar fotovoltaica em Portugal
No full textRESMO: Na versão revista em junho de 2023 do Plano Nacional de Energia e Clima, as perspectivas de evolução da capacidade instalada para a produção de electricidade através das tecnologias eólica e solar fotovoltaica no horizonte 2030 são as seguintes: Eólica: 124 GW (dos quais 104 GW onshore e 2 GW offshore); Solar Fotovoltaica (PV): 204 GW (dos quais, 142 GW serão centralizados e 55 GW descentralizados. Estes valores correpondem a um cenário associado a um aumento muito significativo na procura de energia resultante de diversos projetos insdustriais verdes, e outros, previstos serem iplementados em Portugal na presente década.info:eu-repo/semantics/publishedVersio
Possible industrial applications for Angolan Kalahari sands
No full textRESUMEN: Las arenas de color amarillo ocre con poca o ninguna matriz procedentes de la Formación Arenas Ocres (Mio-Plioceno) y las arenas lavadas de colores claros del Cuaternario (Oliveira y Sousa, 2021), presentes en la cuenca del Kalahari, se extienden sobre una vasta área en el SO de Angola, presentando una gran homogeneidad en todos los niveles a lo largo de esa cuenca. Sin embargo, muestran características
morfológicas similares a las de las arenas del desierto y, como tales, no son adecuadas para usos más
comunes en la obra civil, como el agregado de cemento. Son arenas de tamaño de grano generalmente 98.5% y un reducido contenido en elementos penalizadores. Considerando la granulometría y el análisis químico, estas arenas tienen posibles usos en sectores de la industria cerámica y del vidrio, dependiendo, para aplicaciones menos exigentes, de métodos de beneficio sencillos, en particular para reducir el contenido de alúmina y especialmente de óxidos de hierro concentrados en los recubrimientos que a menudo afectan parcialmente a los granos. Estos pueden reducirse mediante lavados y tratamientos simples de fricción.ABSTRACT: The ochre-yellow sands with little or no matrix from the Ochre Sands Formation (Mio-Pliocene) and the Quaternary light-toned washed sands (Oliveira and Sousa, 2021), occurring in the Kalahari basin,
extend over a vast area in SW Angola, presenting great homogeneity at all levels throughout that basin. However, they show morphological characteristics similar to desert sand and as such are not suitable for
more common uses in construction industry, such as cement aggregate. These are sands with a grain size generally 98.5% and a reduced content of penalizing elements. Considering the grain size and chemical analysis, these sands have possible uses in sectors of the ceramic and glass industry, depending, for less demanding applications, on simple beneficiation methods, namely to reduce the content of alumina and especially iron oxides concentrated in coatings, which often partially affect the grains and can be reduced by washing and simple friction treatments.N/
RES.Trade: An Open-Access Simulator to Assess the Impact of Different Designs on Balancing 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. This work presents the open-access Multi-agent Trading of Renewable Energy Sources (RES.Trade) system, which includes different market designs of the imbalance settlement and the secondary and tertiary reserves. A new imbalance settlement is also proposed in this work. The main features of RES.Trade are demonstrated using two case studies and projected 2030 scenarios: the first analysed four imbalance settlement mechanisms in Portugal, achieving a 43% reduction in penalties using the new method; the second case study assesses the impact of five procurement mechanisms of secondary power reserves in the Spanish power system, resulting in a cost reduction by 34% in the case of dynamic reserves.info:eu-repo/semantics/publishedVersio
Corrigendum to “Critical raw materials in the global high-throughput ceramic industry” [Sustainable Materials and Technologies 39 (2024) e00832]
No full textABSTRACT: The authors regret that an error in the unit of the global output of boron occurred: the correct value is 4.13 million tons per year of borates, corresponding to 2.29 million tons B2O3 in 2018. Thus, the presumable
consumption of borates by the ceramic industry (around 250,000 tons per year, B2O3 content) corresponds to 11 ± 1% of the global output of borates. In comparison, estimates from the mining industry (Orocobre 2019 Annual Report; EtiMaden 2022 Boron Report) place the borate demand for the production of ceramic frits at a share of 14%, corresponding to approximately 320,000 tons per year (B2O3 content).info:eu-repo/semantics/publishedVersio
Screening and Engineering Yeast Transporters to Improve Cellobiose Fermentation by Recombinant Saccharomyces cerevisiae
No full textABSTRACT: Developing recombinant Saccharomyces cerevisiae strains capable of transporting and fermenting cellobiose directly is a promising strategy for second-generation ethanol production from lignocellulosic biomass. In this study, we cloned and expressed in the S. cerevisiae CEN.PK2-1C strain an intracellular beta-glucosidase (SpBGL7) from Spathaspora passalidarum and co-expressed the cellobiose transporter SiHXT2.4 from Scheffersomyces illinoinensis, and two putative transporters, one from Candida tropicalis (CtCBT1 gene), and one from Meyerozyma guilliermondii (MgCBT2 gene). While all three transporters allowed cell growth on cellobiose, only the MgCBT2 permease allowed cellobiose fermentation, although cellobiose consumption was incomplete. The analysis of the beta-glucosidase and transport activities revealed that the cells stopped consuming cellobiose due to a drop in the transport activity. Since ubiquitinylation of lysine residues at the N- or C-terminal domains of the permease are involved in the endocytosis and degradation of sugar transporters, we constructed truncated versions of the permease lacking lysine residues at the C-terminal domain (MgCBT2 Delta C), and at both the C- and N-terminal domain (MgCBT2 Delta N Delta C) and co-expressed these permeases with the SpBGL7 beta-glucosidase in an industrial strain. While the strain harboring the MgCBT2 Delta C transporter continued to produce incomplete cellobiose fermentations as the wild-type MgCBT2 permease, the strain with the MgCBT2 Delta N Delta C permease was able to consume and ferment all the cellobiose present in the medium. Thus, our results highlight the importance of expressing cellobiose transporters lacking lysine at the N- and C-terminal domains for efficient cellobiose fermentation by recombinant S. cerevisiae.info:eu-repo/semantics/publishedVersio