RISE – Research Institutes of Sweden
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Direct conversion of sawdust into biobased aviation fuel precursor via atmospheric catalytic hydropyrolysis process
No full textThis research aimed to develop catalyst and technology design to selectively convert sawdust into bio jet fuel (BJF) components via ex-situ catalytic hydropyrolysis (CHP) process. Design of catalyst configuration was carried out considering the fact that an efficient catalyst for biomass pyrolysis process requires (i) an improved diffusion rate of reactants/products to and from the catalyst active sites, (ii) suppression of secondary reactions, and (iii) prevention of deactivation mechanisms. Hence, sawdust was hydropyrolyzed in a customized continuous pyrolysis system and then the pyrolysis vapors were upgraded while passing through a bed of a well-designed guard catalyst (CatG) followed sequentially by a suitable hydroconversion catalyst (CatH). The morphology and chemical structure of CatG and CatH were synergistically designed to enhance the selectivity towards aromatic hydrocarbons in the range of jet fuel chemicals for 75 %. Effects of different process parameters, such as structure and morphology of CatG, catalyst upgrading temperature (350 and 400 °C), pyrolysis gas environment (N2, H2/N2, and air/N2), concentration of CatG active sites (8, 17, 33, and 50 wt%), and durability of catalysts, on the process efficiency concerning reaction selectivity towards BJFs, heating value of the pyrolysis products, and carbon efficiency of the whole process were investigated. Specifically, the durability of combined catalysts was evaluated for four times and the results showed that the catalysts combination resulted in similar selectivity to BJFs during recycling tests. The maximum selectivity to BJFs (42 %) was achieved at 400 °C, WHSV 3 h−1, reaction time 3 h, carrier gas H2/N2, and CatG 33 wt%. The authors would like to thank the Swedish Energy Agency for financially supporting this study via the project P2021-00086.</p
Contaminations from Lithium-Ion Battery Fires—Per- and Polyfluoroalkyl Substances (PFAS) in Soot
No full textFluorinated substances are widely used in the different components of the lithium-ion battery cell, such as electrode binders, electrolyte, additives and separator materials. To date, most studies regarding the fluorinated contaminations from lithium-ion battery fires are focused on the gases formed, whereas the solids produced are not as well characterized. Here, we present an experimental study investigating the occurrence of per- and polyfluoroalkyl substances, in soot and particulates formed after thermal runaway in lithium-ion battery cells. Per- and polyfluoroalkyl substances were detected in every battery cell test performed in this study. The concentration of per- and polyfluoroalkyl substances ranged between 20 to 130 ng/gsoot. Extrapolation of data gives an estimated release of 10 to 60 µg of per- and polyfluoroalkyl substances per kg battery cells. Among the 22 per- and polyfluoroalkyl substances analyzed, perfluorobutanesulfonic acid and perfluorobutanoic acid were found in the highest concentrations for all samples. Interestingly, perfluorooctanoic acid was detected in all tests, in concentrations ranging between 0.05 to 0.62 ng/gsoot. These findings are of importance not only for the purpose of decontamination after thermal runaway events, but also when it comes to the lithium-ion battery recycling processes. This work was funded by Vinnova (Grant No. 2019-00064) through Batteries Sweden (BASE)</p
Risk Classification Analysis Service for the EU AI Act
No full textThis report presents the Risk Classification Analysis Service developed at RISE to support early implementation of the EU Artificial Intelligence Act (Regulation (EU) 2024/1689). The service offers a structured methodology for preliminarily assessing whether AI systems may fall under the Act’s High-Risk category and for identifying related compliance measures. It combines questionnaire-based information collection, analytical workshops, and preliminary classification, resulting in a final report that documents assumptions, explains the rationale for the classification, highlights compliance gaps, and provides recommendations for preparation toward conformity assessment. Pilot applications in manufacturing and energy showed that classification outcomes depend strongly on deployment context and on how regulatory criteria are interpreted, particularly when determining whether an AI system falls within an Annex III area, supports critical-infrastructure operation, or functions as a safety component of an Annex I–regulated product. The report also summarises key findings, challenges and lessons learned from applying the methodology in practice.CitCom.a
Hybrid Discrete-Finite Element method for biaxially-discretized structures
No full textThe HybriDFEM method, short for Hybrid Discrete-Finite Element Method, combines both discrete and finite element approaches in a single numerical model: the method adopts a discrete representation of the structure, but the formulation is designed to integrate continuous parts that can be simulated by the Finite Element Method, allowing hybrid numerical mock-ups to be built. The scope of application of the method is expanded from its original development for uniaxially-discretized (1D) structures to modeling biaxially-discretized (2D) structures and systems of beams connected through rigid-node connections. The possibility to integrate finite elements within HybriDFEM in 2D is initially formalized. A two-step contact detection algorithm, in which the interface detection is preceded by a preliminary rough detection, is then presented. Finally, different approaches to modeling contact are introduced, depending on whether it is meant to reflect the behavior of a continuous material, flexible interfaces, or point-wise contact. These new capabilities of the 2D HybriDFEM method are validated on a series of selected examples including solutions from analytical models, classical finite elements, and limit analysis; among others, the HybriDFEM method is used to evaluate the axial and shear stress distribution in a linear elastic beam with negligible error relative to analytical solutions, and to predict the collapse load of in-plane loaded masonry frames with an error below 0.05% compared to solutions from limit analysis. The adequacy of the method to enhance discrete simulations by integrating finite elements is illustrated in a conclusive example via the pushover analysis of a flexible masonry frame
Oxy-fuel combustion of softwood in a pilot-scale down-fired pulverized combustor – Fate of potassium
No full textOxy-fuel biomass combustion can facilitate carbon capture in heat and power plants and enable negative carbon dioxide (CO2) emissions. We demonstrate oxy-fuel combustion (OFC) of softwood powder in a 100-kW atmospheric down-fired pulverized combustor run at a global oxidizer-fuel equivalence ratio of around 1.25. The simulated oxidizer was varied between oxygen (O2)/CO2 mixtures of 23/77, 30/70, 40/60 and 54/46, and artificial air. The concentrations of the main gaseous potassium (K) species: atomic K, potassium hydroxide (KOH) and potassium chloride (KCl), were measured at two positions in the reactor core using photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS). Major species were quantified by TDLAS in the reactor core and with Fourier transform infrared spectroscopy and mass spectrometry at the exhaust. Flue gas particles were collected at the exhaust employing a low-pressure impactor and analyzed by X-ray powder diffraction and scanning electron microscopy. The measured individual K species concentrations in the reactor core agreed with predictions by thermodynamic equilibrium calculations (TEC) within one order of magnitude and the sum of K in the gas phase agreed within a factor of three for all cases. Atomic K was underpredicted, while the dominating KOH and KCl were slightly overpredicted. The ratios of measured to predicted total K were similar in artificial air and OFC, but the distributions of the individual species differed at the upper reactor position. The gaseous K species and fine particle concentrations in the flue gas were directly proportional to the O2 content in the oxidizer. The crystalline phase compositions of the coarse mode particles were rich in K- and calcium-containing species. The fine mode particles, which contained most of the K, consisted mainly of K2SO4 (94%) and K3Na(SO4)2, which is in excellent agreement with TECs of gas phase condensation. As supported by the solid phase analysis, complete sulfation of K species was achieved for all studied cases. A CO2 purity (dry) of up to 94% was achieved for OFC. The authors acknowledge financial support from the Swedish Energy Agency and the Kempe Foundations. The long-term support from the Swedish Strategic Research Environment Bio4Energy for our activities is highly appreciated.</p
Predictive modeling and estimation of moisture damages in Swedish buildings: A machine learning approach
No full textIdentifying potential moisture damage is crucial for maintenance practices and assurance of well-being of oc cupants. However, due to limited information availability and standardization, assessing damage prevalence on the building stock scale remains understudied. By combining investigation records and building databases, this study leverages data analytic techniques and machine learning modeling to characterize damage pathology and predict its occurrence in Swedish buildings. The interrelationships between damage-specific attributes and their associations with building parameters of several damage types were analyzed using feature selection, forming the basis for developing predictive models. Results show that multilabel classifiers outperform binary classifiers for every damage type, with lead tree ensemble models achieving minimum average AUCPR and F2 of 0.85 for microbial growth, 0.87 for deformation, 0.91 for odor, and 0.95 for water leakage. The identified patterns were interpreted and verified against descriptive statistics. The binary relevance models estimate that one-third of school buildings, 20 % of commercial and office buildings, and 15 % of residential dwellings in regional building stock contain moisture damage. These findings advance the quantification of moisture damage by providing new knowledge and approaches for appraising moisture damage likelihood at aggregated and individual building levels, thereby aiding in moisture safety evaluations and preventive maintenance effortsThe research fund comes from Lansf ¨ ors ¨ ¨akringar (County Insurance) for the project predicting moisture damage in existing and new buildings using AI (machine learning) with the program ID P4:22</p
Pipeopsy : A Novel Method for Status Assessment of District Heating Pipes in Operation
No full textThis study presents a novel status assessment method for district heating (DH) pipelines in operation, which we call "Pipeopsy"(a biopsy for pipes). The method evaluates adhesion strength between the service pipe and polyurethane (PUR) insulation, which is a crucial property for the durability of DH pipes and the extent of degradation of PUR foam closest to the service pipe. This method is based on three parts: (1) measuring adhesion strength and taking samples of the foam, (2) analyzing the foam in a laboratory using Fourier-transform infrared (FTIR) spectroscopy, and (3) restoring pipeline by replacing the foam and sealing the casing by welding polyethylene plugs in the holes. Temperature dependence and measurement accuracy of the shear strength test method have also been examined, as well as correlation with the standard axial shear strength test method. The shear strength of the aged pipes shows no temperature dependence, while the quotient between the value produced with the plug method and axial method is 3.1. Compared with the standard test methods, the advantages of Pipeopsy involve small cost, less damage to pipes, and the use of simple mobile tools for taking samples and performing measurements. Importantly, testing can be performed without shutting down the operation of DH pipelines. Furthermore, the method provides not only the information on adhesion strength but also information on the extent of chemical degradation in PUR. This combination of information provides a more detailed picture of the status of pipes and can be used to make a prediction about the remaining lifetime. Pipeopsy produces many results in a short time, and better statistics, which provide a solid basis for decision-makers focused on the maintenance of DH pipes or for applying artificial intelligence. This work was financed directly by Energiforsk, the SwedishEnergy Agency. RISE and Swedish energy companies (VattenfallAB, Öresundskraft AB, Göteborg Energi AB, Jönköping EnergiAB, E. ON Energilösningar AB, Kraftringen AB, Gävle EnergiAB) contributed with in-kind work and gave access to field mea-surement test sites in their networks. Powerpipe Systems AB con-tributed with in-kind work and produced test pipe</p
Exploring the social impact of paratransit : A systematic literature review with a micro-level perspective
No full textThis systematic literature review examines the social impact of paratransit from a micro-level perspective, offering insights into how this mode of transportation influences individuals’ daily lives. Using the PRISMA methodology, 33 publications were identified following an iterative screening process. Five key themes emerged: Barriers, Safety and Risk Concerns, Gender and Socio-Economic Influences, Users’ Opinions and Lived Experiences, and Travel Behavior – Influences and Determinants. The review reveals that paratransit services present significant challenges, particularly for the elderly and disabled, restricting autonomy and social inclusion. Although safety concerns and dissatisfaction with service reliability and cleanliness were common, these issues did not result in notable changes in travel behavior, as users frequently lacked viable alternatives due to financial constraints. Notably, most reviewed studies were conducted in the Global South, which may limit the generalizability of findings to high-income or Western contexts. The review emphasizes the need to address both basic and psychological needs to enhance positive social impact of paratransit, especially in regions where income inequality shapes transportation options. Additionally, standardizing terminology is crucial to ensure consistency in future research. The research was supported by grants from the Swedish Energy Agency (2022-00411) and from Formas (2024-01258).</p
Impact of Steam-Exploded Feather Incorporation on the Biodegradation Performance of Renewable Biocomposites
No full textThe increasing environmental concerns regarding plastic waste, especially in agriculture, have driven the search for sustainable alternatives. Agricultural plastics, such as mulching films and greenhouse covers, are heavily reliant on petrochemical-derived materials, which persist in the environment and contribute to long-term pollution. This study explores the use of biodegradable biocomposites made from steam explosion-treated chicken feathers and various polymer matrices to address these issues. Chicken feathers, a waste by-product of the poultry industry, present an excellent biodegradability as a result of the steam explosion treatment and contain nitrogen, potentially enhancing soil fertility. The biocomposites were characterized by thermal stability, mechanical properties, and biodegradability, and ecotoxicity assessments were carried out studying the incorporation of feathers into the soil. Results showed that the incorporation of treated chicken feathers increased the water absorption capacity of the composites, promoting faster disintegration and biodegradation. In particular, biocomposites made with polyhydroxyalkanoates and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) exhibited a significant increase in degradation rates, from 3–10% in the first month for pure matrices to 40–50% when reinforced with treated feathers. Meanwhile, those made from polylactic acid showed slower degradation. Furthermore, the addition of feathers positively influenced crop growth at low concentrations, acting as a slow-release fertilizer. However, high concentrations of feathers negatively affect plant growth due to excess nitrogen. These findings highlight the potential of poultry feathers as a valuable, sustainable filler for agricultural bioplastics, contributing to waste valorization and environmentally friendly farming practices. This project has received funding from the Bio-based Industries Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101023306. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Bio-based Industries Consortium</p
Syngas fermentation for hydrogen and volatile fatty acids production : Effect of inoculum source, pretreatment, and environmental parameters using natural microbial consortia
No full textThis study evaluates the biological water-gas shift reaction of syngas into hydrogen (H2) using natural microbial consortia from wastewater treatment facilities. Various inoculum pretreatment techniques to inhibit methanogenesis and different operational conditions such as temperature, pH, and inoculum concentrations were tested to improve H2 production. An inoculum heat pretreatment of 85 °C for 30 min followed by a fermentation temperature of 65 °C and an initial pH value of 9, resulted in the maximum CO-to-H2 conversion (2.35 ± 0.00 mmol) in which Firmicutes dominated with a total inhibition of methanogens, such as with the chemical inhibition treatment. Additionally, volatile fatty acids (VFA) production was observed, being influenced by the pre-treatment. This study highlights the potential of natural consortia for efficient, cost-effective and scalable syngas fermentation processes, offering new insights into the bioconversion of H2 without costly chemical inhibitors. This work was financially supported by the European Project, SynoProtein, via the HORIZON JU Innovation Actions program (No. 101112345).</p