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- Inter-equipment ongoing validation of microplastic identification by micro-FTIR using optimal resourcesPublication . Fernandes, Rafaela; Miclea, Paul-Tiberiu; ROSSI, Andrea Mario; Giovannozzi, Andrea M.; Putzu, Mara; Morgado, Vanessa; Palma, Carla; Almeida, José Miguel; Pedro, Matilde São; Drago, Claudia; Quendera, Raquel Maria Pina Amaral; Pellegrino, Olivier; Bettencourt da Silva, RicardoABSTRACT: FTIR is widely used for identifying microplastics due to its performance and affordable equipment. However, there is a need for a universal method for the automatic identification of microplastics by FTIR, robust to different spectra collection conditions, and capable of adapting to the diversity of particle spectra. This research presents a method for developing a reliable and simple algorithm for inter-instrumental microplastic identification using micro-FTIR. Spectra collected from different equipments and settings across various laboratories, from microparticles previously confirmed as PET (positive cases) and non-PET (negative cases), were compared with a PET reference using multiple algorithms (match methods) based on six weighted and unweighted correlation coefficients. After excluding low signal-to-noise spectra with a newly developed universal algorithm, the 5th percentile of the match values for positive cases, estimated using a robust bootstrap method, was used as a minimum match (P5 & raquo;P) to ensure a 95% true positive rate (TP). Assuming a normal distribution of the match values for negative cases, the false positive rate (FP) was calculated. The best method identified uses an unweighted correlation of differentiated signals, resulting in a P5 & raquo;P = 0.4140 and FP = 0.0005% for spectra with a minimum signal-to-noise ratio of three. This identification performance, estimated from 117 spectra, is statistically equivalent to that observed from the identification of 405 additional particles using the validated method, at a 99% confidence level set by the Clopper-Pearson method, thereby extending the method's applicability to 522 particles. The developed method for PET identification by FTIR is robust across various acquisition conditions and instruments, was implemented in a user-friendly MS Excel spreadsheet, and can be easily tested with more particles and different instrumental settings. The validity of the identification algorithm and the defined criteria cannot be extrapolated to a different reality with respect to spectral collection conditions and the diversity of negative cases without a prior performance assessment.
- Advances of Hydrothermal Biomass Liquefaction Using Microalgae: Process Parameters and Biocrude Upgrading MethodsPublication . Martins, Marta; Fernandes, Marcelo Domingos; Rodrigues, Alda J.; Costa, Paula; Gírio, FranciscoABSTRACT: The ReFuelEU Aviation Regulation introduces mandatory targets for sustainable aviation fuels (SAF) from 2025 to 2050. However, hydrotreated esters and fatty acids (HEFA) technology based on waste oils alone is insufficient to meet targets beyond 2030, highlighting the need for alternative biocrude feedstocks to increase SAF production in the EU. Microalgae are promising feedstocks due to their biochemical composition and CO2-utilization potential, although their high moisture content and nitrogen and oxygen levels require energy-efficient conversion technologies. Hydrothermal liquefaction (HTL) is a suitable process for converting wet microalgal biomass into biocrude, with an optimal temperature window of approximately 300-330 degrees C and typical biocrude yields ranging from 20 to 70 wt%, depending on feedstock composition and operating conditions. However, microalgal HTL remains at TRL 5-7 and faces challenges related to the high heteroatom content of the resulting biocrude. Hydrodeoxygenation (HDO) is a key upgrading step for converting biocrude into drop-in aviation fuels and commonly operates at approximately 250-400 degrees C and 10-30 MPa H2 pressure. Nevertheless, few studies have addressed the HDO of microalgae-derived biocrude. This review examines microalgal HTL, pilot and demonstration facilities, biocrude yields and quality, and upgrading strategies for producing synthetic drop-in aviation biofuels.
- Protic Imidazolium Ionic Liquids for Electroreduction of CO2Publication . Messias, Sofia; Paninho, A. B.; Pires, Carolina; Rangel, Carmen M.; Martins, Rodrigo; Mendes, Manuel Joao; Branco, Luis; Machado, AnaABSTRACT: Protic ionic liquids characterized by permutable protons have important applications in electrochemistry. This work represents an unprecedented report of the use of such electrolytes for CO2 electroreduction (ECR) into CO at 10 bar and near room temperature (45 degrees C) on zinc electrodes. It was observed that when protic ILs are synthesized from strong acids, the competition with the hydrogen evolution reaction increases. In contrast, the use of softer acids in the synthesis significantly enhances CO production. Imidazolium-based protic ILs were chosen due to their known high CO2 solubility and consequently their potential to increase reaction productivity. The electrolytes were electrochemically characterized, their conductivities and diffusion coefficients were determined, and their performance was compared. Despite the aqueous nature of the electrolyte, remarkably, 100% Faradaic efficiencies were obtained with [HMIM][Lac] containing 50 wt % water. The performance of the aqueous protic 50 wt % [HMIM][Lac] electrolyte surpassed the performance of the non-protic 50 wt % [EMIM][OTf] electrolyte. Furthermore, among the investigated water concentrations, the maximum CO production for the protic 50 wt % [HMIM][Lac] (177 & micro;mol/cm2) is of the same order as the magnitude of 90 wt % [EMIM][OTf] (271 & micro;mol/cm2), an almost pure IL, more expensive, and less sustainable electrolyte. The non-fluorinated bio-based lactate anion concurs to the higher sustainability of the process. Hydrophilic protic ILs are thus promising as electrolytes for ECR.
- Lithium Role in the Clean Energy Transition: Challenges and ProspectsPublication . Almeida, Joana; Pedrosa, Fátima; Plancha, Maria João; Gonçalves, Ana; Nogueira, CarlosABSTRACT: Global decarbonization strategies depend on the large-scale electrification of the transport sector, mainly supported by lithium-ion battery technologies. Lithium’s role in assisting low-carbon mobility has driven a fast rise in demand. This has intensified concerns regarding resource scarcity and supply chain vulnerabilities, particularly in the European Union, which remains heavily dependent on imports. The restricted availability of lithium and other critical raw materials, compounded by geopolitical tensions, poses a risk to the resilience of the clean energy transition. In this sense, the adoption of circular economy principles has emerged, emphasizing material recovery, recycling, and resource efficiency. This review provides a comprehensive analysis of lithium relevance in the energy transition, with a focus on resource trends, recovery technologies, and battery production. A systematic understanding of these trends and challenges is needed to guide future developments and ensure a secure, sustainable, and circular lithium value chain that supports the transition to clean energy systems.
- Estudos Técnicos para o Potencial Energético Offshore: Projeto LNEG EOLOS.MarPublication . Estanqueiro, Ana; Simões, Teresa; Couto, António; Costa, Paula Silva; Justino, Paulo AlexandreABSTRACT: O projeto EOLOS.Mar, desenvolvido pelo Laboratório Nacional de Energia e Geologia (LNEG) no âmbito do investimento PRR RP-C21-i07.02 – Estudos Técnicos para o Potencial Energético Offshore, constituiu uma iniciativa estruturante para apoiar o desenvolvimento da energia eólica offshore em Portugal. Ancorado nos objetivos nacionais do PNEC 2030 – Plano Nacional de Energia e Clima, o projeto teve como principal objetivo realizar a caracterização experimental dos recursos energéticos marinhos em 4 áreas prioritárias da costa continental portuguesa, áreas essas definidas no Plano de Afetação para as Energias Renováveis Offshore (PAER, versão 2023) produzindo, assim, informação técnico-científica indispensável ao planeamento e à futura instalação de centros eletroprodutores offshore. A abordagem adotada assentou na realização de campanhas experimentais concebidas segundo as melhores práticas internacionais para avaliação do recurso eólico offshore, seguindo recomendações da International Energy Agency (IEA Wind TCP), da Offshore Wind Accelerator (OWA) e das normas internacionais da International Electrotechnical Commission (IEC). Para minimizar as incertezas inerentes à caracterização do vento sobre o mar, foi implementada uma estratégia integrada de monitorização baseada na operação simultânea de sistemas LiDAR (Light Detection and Ranging) flutuantes, coadjuvados por sistemas LiDAR costeiros de referência e por mastros meteorológicos e anemométricos convencionais, permitindo combinar as vantagens das tecnologias de deteção remota com medições de referência de elevada fiabilidade. As campanhas experimentais abrangeram quatro áreas marítimas representativas das zonas definidas na versão inicial do PAER, totalizando cerca de 2452 km² de área monitorizada ao largo da costa continental portuguesa. A seleção das localizações, da instrumentação e da duração das campanhas foi cuidadosamente planeada para assegurar a obtenção de dados representativos do recurso eólico offshore e, simultaneamente, caracterizar parâmetros oceanográficos relevantes para o desenvolvimento, operação e manutenção de futuras centrais eólicas, incluindo ondulação, correntes marítimas e variáveis meteorológicas complementares. O projeto envolveu a instalação e operação de quatro sistemas LiDAR flutuantes, dois sistemas LiDAR costeiros e duas estações meteorológicas de referência, constituindo uma infraestrutura experimental sem precedentes em Portugal, para caracterização integrada do ambiente offshore. Os sistemas permitiram monitorizar perfis verticais do vento até altitudes compatíveis com os rotores das atuais turbinas eólicas de grande potência, bem como recolher informação sobre temperatura, humidade, pressão atmosférica, estado do mar e correntes marítimas, disponibilizando um conjunto alargado de variáveis essenciais à avaliação técnica e económica de futuras centrais renováveis offshore.