Browsing by Issue Date, starting with "2024-05"
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- Biogas reforming as a sustainable solution for hydrogen production: Comparative environmental metrics with steam-methane reforming and water electrolysis in the Portuguese contextPublication . Bento, Cláudia; Lopes, Tiago; Rodrigues, Pedro; Gírio, Francisco; Silva, CarlaABSTRACT: This study delves into the dynamics of hydrogen production, with a specific focus on biogas reforming (BGSMR) for hydrogen generation. It compares the environmental impact of this solution with hydrogen production from natural gas-steam reforming (NGSMR) and commercial electrolysis in the Portuguese context. Various metrics, including carbon footprint, water depletion, energy utilization, and waste valorization are employed for a comprehensive comparison. The assessment explores the impact of operational parameters and different off-gas combustion scenarios, incorporating water recycling practices. Due to challenges in obtaining detailed data on the actual reforming process, the study relies on process simulation techniques, primarily using DWSIM. Commercially available data for water electrolysers were used for comparison. In the context of decarbonizing power systems, hydrogen from water electrolysis emerges as a competitive option only in a scenario where the power system is 100% reliant on renewable sources, particularly with respect to the carbon footprint metric. Biogas systems, characterized by near-zero carbon emissions, stand out as a favourable option from the near future to the long run. This research contributes valuable insights into the dynamics of hydrogen production, shedding light on environmentally viable alternatives across a range of power system scenarios.
- Electrical driven pyrolysis reactor retrofit for indirect concentrated solar heatPublication . Azevedo, Pedro; Costa, PaulaABSTRACT: Aiming for a climate-neutral economy, and the associated transition towards fuels produced from alternative feedstock, and to overcome some biomass pyrolysis unsuitable properties for the conventional combustion devices, plastics pyrolysis also produces oils, whose main compounds are also hydrocarbons, that can be used in conventional engines without so complex and costly upgrading processes. Most of the chemical reactions found in a pyrolysis process are endothermal thus, to fulfill that energy demand, the retrofit of a 4 kW electrical furnace pyrolysis reactor to indirect solar driven energy was assessed aiming to adapt it to a central receiver solar tower with up to 100 kWth-peak, using air as heat transfer fluid. The heat demand along a typical pyrolysis test was experimentally assessed and a heat transfer mathematical model was defined to address the working constraints of the reactor. Additional analysis considering new design parameters were performed, namely sensitive analysis to the length of the new heating coil and its overall heat transfer coefficient, the reactor temperature set point, the inlet and outlet (to the atmosphere) gas temperature and working mass flow rates and temperatures were found to provide the same heat demand and minimize the waste heat. Considering both the heat source facility and the reactor constraints, it was found that the retrofit is possible providing that the product of surface area by the overall heat transfer coefficient (A·U) yields more than 17.7 W/K, for a reactor temperature set point of 450 °C and a maximum temperature inlet of 700 °C.
- Sustainability Assessment of 2G Bioethanol Production from Residual Lignocellulosic BiomassPublication . Correia, Bárbara; Matos, Henrique A.; Lopes, Tiago; Marques, Susana; Gírio, FranciscoABSTRACT: The development of sustainable biofuels can help to reduce the reliance on fossil fuels and mitigate the impact of climate change. This study analyzes bioethanol production from agro-forestry residual biomass, namely eucalyptus residues and corn stover. The study includes process simulation using Aspen Plus software, followed by economic analysis and life cycle assessment (LCA) with the help of SimaPro software and by applying the environmental footprint (EF) 3.0 method. The economic analysis on the biorefinery’s economic viability, equipment, and production costs reveals a positive decision for bioethanol production from eucalyptus residues due to logistical and transportation costs. The minimum ethanol selling price (MESP) obtained was 2.19 €/L and 2.45 €/L for eucalyptus residues and corn stover, respectively. From the LCA with a functional unit of 1 MJ of ethanol, bioethanol production from eucalyptus residues results in a single score impact of 37.86 µPt, whereas for corn stover, it is 33.47 µPt. In the climate change impact category, the eucalyptus residues scenario has an impact of 0.264 kg CO2 eq/MJ ethanol while corn stover leads to 0.254 kg CO2 eq/MJ ethanol. In-situ enzyme production, heat integration, and the use of renewable energy sources were also analyzed. Combining in situ enzyme production with renewable energy sources lowers CO2 equivalent emissions by 89% for both feedstocks, in comparison to the base-case scenario.
- START Newsletter: Recover-Reform-Reuse for a Sustainable Future, Issue 4Publication . Neves, Filipe; Vicenzi, BrunoABSTRACT: We are almost halfway through the project activities and what a journey this has been! The advances we have made together are nothing short of remarkable. This edition of our Newsletter is a testament to our collective dedication and the exciting progress we’ve achieved. The completion of our first Periodic Report marks a significant milestone, and the advancements in tetrahedrite mineral-based thermoelectric materials are not just promising—they’re a leap towards a sustainable future. We’re excited to share updates on our ongoing activities, our synergistic collaborations with the EHRASE cluster and THERMOS project, and insightful technical information on thermoelectric generators. But that’s not all, join us on the Consortium Tour, where this time SGUDS and IGME-CSIC take centre stage. Plus, don’t miss the insightful interview with Doug Crane from our Scientific Advisory Board, whose expertise enriches our understanding of thermoelectrics. This edition also features the fascinating adventures of Starty, exploring the practical uses of thermoelectric devices in a narrative that’s both educational and engaging. Looking ahead, we eagerly anticipate your visit to the START booth at the upcoming 40th International and 20th European Thermoelectric Conference, ICT/ECT 2024, in Krakow. We hope this Newsletter serves not only as a source of information but also as an inspiration for continued excellence. Stay connected with us for more exciting updates from START on our website and social media channels.
- Tuning cathode porosity for electrochemical reduction of CO2 at high pressure [Resumo]Publication . Messias, Sofia; Fialho, Maria T.; Paninho, A. B.; Nunes, A. V. M.; Branco, Luis C; Nunes, D.; Martins, Rodrigo; Mendes, Manuel Joao; Rangel, C. M.; Machado, AnaABSTRACT: The development of active and stable catalytic cathodes is critical for advancing electrochemical carbon dioxide reduction into fuels and chemicals from Lab to market. This is a technology with a high potential to contribute to combat climate changes by using captured CO2, water and renewable energy [1]. The use of pressures higher than atmospheric pressure to carry out the co-electrolysis of CO2 and water has been recognized as an important process intensification parameter to increase productivities and energy efficiency [2]. Ongoing work addresses the preparation of aerogels by the sol gel method and impregnation with zinc and copper metallic particles to be used as cathodes for the co-electrolysis of CO2 and water to produce syngas at temperatures near room temperature and high-pressure. Ionic liquid-based electrolytes are used to increase CO2 concentration at the surface of the electrode and consequently productivities, as some ionic liquid families are known to solubilize high amounts of CO2. Aerogels have been investigated for many different applications including as catalyst supports, due to their high surface area, stability in gaseous or liquid phases, and efficient transport through large meso and macropores. The present work reports a strategy to tune the pore sizes of the catalytic electrodes by the use of reticulating agents and supercritical CO2 drying. Productivities and faradaic efficiencies of the porous materials with the different reticulating agents are compared and interpreted in respect to their surface characterization e.g. BET surface areas and morphologies determined by SEM. The potential of new aerogel-based catalytic cathodes on the efficiency of the electrochemical CO2 reduction will be discussed and its impact in fostering supercritical fluids technology through its use in processes for the mitigation of climate changes.
- Desenvolvimento de um fotobiorreator, em escala de bancada, com um novo sistema de recirculação para cultivo contínuo de microalgas - Patente nacional: PT 118320 (A)Publication . Tavares, João; Alves, Luís; Paixão, Susana M.; Silva, TiagoRESUMO: A presente invenção traduz-se no Desenvolvimento de um fotobiorreactor (FBR) para o crescimento fotoautotrófico contínuo de microalgas, num sistema quimiostato, à escala de bancada. este novo fbr integra um vaso de retenção, que garante a mistura das fases líquidas e gasosas e centraliza o controle dos parâmetros e condições de cultura, um fotocoletor, que maximiza a área iluminada e a fixação do carbono através da fotossíntese, um desgaseificador, que previne a acumulação do oxigénio e assegura a recolha, e um novo conceito de recirculação que propicia uma cultura homogénea ao longo de todo o conjunto integrado funcionando como um único quimiostato. o protótipo do fbr desenvolvido está ilustrado no esquema da figura 1 (desenho sem considerar qualquer escala):(1) Recipiente de meio de cultura fresco; (2) Compressor de ar: g) fluxo de Ar (corrente gasosa contendo dióxido de carbono); (3) Bomba peristáltica; (4) Rotâmetro de precisão; (5) Bomba de recirculação da cultura autotrófica; (6) Câmara de gotejamento; (7) Conector em Y; (8) controlador de PH; (9) Banho termostatizado; (10) Vaso de retenção: A) Sensor de temperatura, B) Sonda de PH, C) Hélice de agitação magnética, D) Entrada da solução controladora de PH, E) Tubo borbulhador, F) Tubo nivelador; (11) Controlador de agitação; (12) Fotocoletor ¿ Série de colunas de bolhas (K); (13) Tomadas/ligações de acoplamento; (J) Cabeça lavadora de gases; (14) Desgaseificador: I) Tubo de descarga para colheita (para um recipiente de amostragem ou de colheita); (15) Condensador: H) Fluxo de ar de escape; (16) Analisador de gases.
- Pressurized pyrolysis of mattress residue: An alternative to landfill managementPublication . Serrano, Daniel; Horvat, Alen; Mata, Ricardo M.; Costa, Paula; Paradela, FilipeABSTRACT: Mattresses are a difficult waste to manage in landfills due to their large volume and low density. Pyrolysis treatment could reduce its volume while producing fuel or products valuable for the chemical industry. Pressurized pyrolysis at 400, 450, and 500 degrees C is carried out in a lab-scale autoclave at initial pressures 4.2, 8.4, and 16.8 bar. Product gas yield increases slightly along with elevated pressure as well as temperature. However, beyond 8.4 bar the initial pressure makes no discernible differences. CO and CO2 are the major gas species followed by CH4. CO contributes the most to the product gas energy content followed by C-3 species, C2H6, and H-2. Calculated energy content (heating value) is between 2 and 15 MJ.Nm(-3). In terms of product gas energy content, low pressure pyrolysis is favorable over high pressure pyrolysis. According to integration areas of chromatographic measurements the liquid phase contains up to 25 % of N-compounds, with benzonitrile being the most abundant, followed by toluene, o-xylene, and ethylbenzene. The solid char maintains constant properties across operating conditions, with carbon and energy contents of approximately 75 wt% and 30 MJ.kg(-1), respectively.
- Corrosão dos aços AISI 316L e AISI 430 em contacto com sais fundidos de carbonatos para armazenamento de energia térmica [Comunicação oral]Publication . Gil, Mafalda; Pedrosa, Fátima; Paiva Luís, Teresa; Figueira Vasques, Isabel; Cunha Diamantino, TeresaRESUMO: Os desafios da transição energética e a tendência crescente da eletrificação da economia implicam uma clara aposta no aumento da utilização de energias renováveis. Nesse sentido, os sistemas de concentração de energia solar (CSP) ganharam considerável relevância na conversão de energia solar térmica em energia elétrica [1]. Com o crescente desenvolvimento e implementação destas tecnologias que utilizam fluidos de transferência de calor (misturas de sais fundidos) para armazenar energia térmica, tem-se revelado cada vez mais premente estudar a durabilidade, a corrosão e a compatibilidade dos materiais estruturais em contacto com estes fluidos, quando submetidos a altas temperaturas [2]. O presente trabalho tem como objetivo estudar as velocidades e os mecanismos de corrosão de dois aços inoxidáveis, o austenítico AISI 316L e o ferrítico AISI 430, em contacto com uma mistura eutéctica de sal fundido de carbonatos de lítio, sódio e potássio, em ensaios de longa duração a 650 °C. A seleção destes dois aços inoxidáveis teve por base as suas diferenças, tanto nas características intrínsecas, como no custo associado a cada um deles. A avaliação da velocidade de corrosão foi efetuada por gravimetria através da metodologia descrita na ISO 17245:2015 [3]. Para ambos os aços, a evolução da velocidade segue uma cinética parabólica apresentando o AISI 430 uma velocidade superior.
- Correction to: Biomass and bioenergy potentials of bioresidues: assessment methodology development and application to the region of LafõesPublication . d'Espiney, Ana; Pinheiro, H. M.; Marques, Isabel Paula; Kretzschmar, Jörg; Cyffka, Karl‑Friedrich; Thrän, DanielaABSTRACT: Bioenergy research aims to uncover the potentials of biological residues. Regional-specific characterization of such potentials is needed to improve the use of local resources, decisions on bioenergy conversion routes, and services within global efforts against climate change. The definition and calculation of the theoretical and technical biomass and bioenergy potentials are keys for developing sustainable use pathways at a regional level. The present work develops a methodology where theoretical framework, quantification methods, and values for the necessary parameters, to assess regional biomass and bioenergy potentials, are considered. The region of Lafoes (Portugal) is the case study to illustrate the application of the methods, resulting in three bioresidue categories (agricultural by-products, forestry residues, and municipal waste) and two bioenergy conversion routes (biochemical and thermochemical). The biochemical conversion route revealed a technical energy potential of 765 TJ yr-1, comparing favourably with the 543 TJ yr-1 achieved by the thermochemical route. Also, the environmental and economic performances, associated with the implementation of bioenergy technologies, are possibly better achieved through the biochemical route, to be assessed through life cycle analyses and life cycle costing. Regardless of action priorities, the two conversion routes combined can potentially cover the entire current electrical energy demand of the region. This should also be appraised with expectations in mind for both flexible bioenergy services (with other renewables) and for bioenergy usage in applications which are difficult to defossilize.
- Chemical composition and structural features of cellolignin from steam explosion followed by enzymatic hydrolysis of Eucalyptus globulus barkPublication . Magina, Sandra; Marques, Susana; Gírio, Francisco; Lourenço, Ana; Barros-Timmons, Ana; Evtuguin, Dmitry V.ABSTRACT: Bark is one of the main wastes of the chemical and mechanical processing of Eucalyptus globulus wood. The proposed biochemical processing of bark via saccharification pathway involves steam explosion (SE) pretreatment (severity factor log R0 of 4.22) followed by enzymatic hydrolysis using an enzymatic cocktail composed of cellulolytic and xylanolytic enzymes. Almost 70% cellulose saccharification was achieved. The remaining cellolignin residue (CLEZ) was analysed for its chemical composition and structural features by conventional wet chemistry methods and a series of spectroscopic tools (FTIR-ATR, solid-state CP/MAS C-13 NMR spectroscopy and wide-angle X-ray scattering (WAXS)). The main CLEZ component (about 51%) is acid-insoluble lignin, the chemical composition of which in terms of the ratio of syringyl (S), guaiacyl (G) and p-hydroxyphenyl (H) units (70:28:2) is very close to that in the initial bark. This lignin is highly condensed and structurally associated with condensed tannins, which makes CLEZ recalcitrant to delignification by common methods. About one third of cellulose in eucalyptus bark after SE was inaccessible to enzymatic hydrolysis and remained in the CLEZ. This cellulose, structurally similar to microcrystalline cellulose, is imbedded into the lignin-tannins condensed matrix and extremely difficult to purify. In contrast to cellulose, bark hemicelluloses were effectively removed in enzymatic hydrolysis, with only small amounts (<2%) remaining in CLEZ. Among other CLEZ ingredients, proteins and inorganic/organic salts were the most abundant. The latter includes noticeable amounts of calcium oxalate phytoliths (up to 9%), Fe and Si salts. The eventual application areas of CLEZ are discussed.