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Fast pyrolysis pathway for production of sustainable aviation fuel (SAF) from demolition wood: Experimental and process simulation approach
No full textThe escalating adverse climate impacts of aviation industry have attracted the attention of research towards the production of sustainable aviation fuels (SAF) for mitigating the climate change. This study aims to investigate the demolition wood as a potential feedstock to produce SAF through fast pyrolysis process. A steady-state process simulation model was developed in Aspen Plus® and validated experimentally. The simulation model developed for SAF production comprises pyrolysis process, hydrotreating of bio-oil, fractionation of hydrotreated-oil, production of H 2 gas through Proton exchange membrane (PEM) electrolyzer, purification of aqueous stream, and combustion of char blocks. The process simulation model has produced 52.8 wt% bio-oil, 20.5 wt% char, and 10.8 wt% gases by using yield-based pyrolysis reactor at operating temperature of 500 °C. Experimental results have demonstrated 49.9 wt% bio-oil yield at 500 °C pyrolysis temperature and 1 s reactants residence time. The simulation model indicated 12.2 wt% SAF yield, and physiochemical properties of SAF were also found consistent with the ASTM D7566 standard. It was also indicated that around 0.07 kg of H 2 per kg of bio-oil is needed for hydro-processing reactions at 99.9 % purity of H 2 gas. The process simulation model also estimated that 36.3 MW of electrical power, 6.9 MW of external heating utility and 11.7 MW of external cooling utility were required to produce 0.12 kg of SAF per kg of feedstock. Overall, the research provides a platform to examine the development of SAF production process through the fast pyrolysis of demolition wood, followed by hydro-processing and fractionation.</p
Electrification of district heating: The impact of electricity price volatility and distribution temperatures on the optimal capacity mix
Get PDFBecause of the increasing share of variable renewable energy in the power sector, the volatility of the electricity price has increased greatly. This, the electricity tax relief, and concerns about sustainability of combustible fuels have boosted the power-to-heat investments in the Finnish district heating systems. Especially, electric boilers, which have been nearly non-existent in the Finnish district heating systems, will see a rapid roll-out in the next few years. In this study, Backbone modelling framework was used to investigate the impact of increasing volatility of electricity price on optimal power-to-heat and thermal energy storage investments in the Finnish capital region. The impact of decreasing district heating temperatures was analysed as well. The sensitivity of the results to energy prices and thermal energy storage costs was tested.The results show that more volatile electricity price increased the profitability of the electric boilers and heat storages. Larger electric boiler capacity led to higher electricity consumption and peak power demand. The profitability of the heat pumps increased significantly with lower district heating temperatures, which also decreased the electricity consumption of the district heating system. The optimal capacity mix of the P2H technologies and heat storages was highly sensitive to the cost assumptions of the fuels and heat storages, but the total costs increased only a little, if the model was run with suboptimal capacity mix. Lower fuel prices decreased the heat pump investments, and higher prices increased. The impact of fuel prices on the electric boiler investments was not as clear
Gaseous ozone treatment of wood:Effect of treatment conditions on the wood wettability and phenol-formaldehyde adhesive bonding strength
Get PDFFindings of an earlier study, “Improving Wood Surface Wettability through Gas-phase Ozone Treatment of Air-dry Wood,” demonstrated that the wood gas-phase ozone treatment enhances the wettability of wood by water, and thus potentially also the spread, absorption, and adhesion of water-based adhesives and coatings to the wood surfaces. This study extends that work by examining the effect of ozone treatment temperature and the wood moisture content on the wettability of ozone treated wood and bonding strength of phenol-formaldehyde (PF) adhesive. In the present study, both air-dry and wetted birch plywood and veneer were ozone-treated at 23 °C, 35 °C, and 55 °C for 10 and 30 minutes. The amount of reacted ozone increased with higher treatment temperature and with an increase in the wood moisture content. However, the reduction in the water contact angle was more pronounced for air-dry wood. Bonding tests showed that the ozone treatments substantially increased the PF adhesive bonding strength, and the bonding strength correlated negatively with the ozone-treated birch veneer water contact angle. The results suggest that both the treatment temperature and moisture content of the wood during the treatment influenced the ozone reactions with wood, and thus on wood wettability and PF adhesive bonding strength (192 / max. 200).<br/
Coupling of shrinking core and Eulerian-Eulerian models for chemical looping combustion
No full textOne of the main barriers to the implementation of chemical looping combustion (CLC) on an industrial scale is the lack of knowledge about its operation at such scales. As a first step towards modeling industrial CLC devices, a consistent coupling between the shrinking core model (SCM) and the Eulerian-Eulerian multiphase framework with multicomponent phases was derived. This coupling enforces the constant volume assumption of a solid particle and allows for simple and consistent control of the oxygen transfer capacity. The derived approach was then applied to the chemical kinetic model of ilmenite redox reactions, which was sourced from the literature and was based on thermogravimetric analysis (TGA) data. Important corrections were made to the kinetic model parameters to ensure consistency with the present methodology, and the result was verified using a zero-dimensional TGA simulation setup. The methodology was further validated using experimental data from the literature for a laboratory-scale batch fluidized bed reactor. Three-dimensional simulations and an analytical one-dimensional quasi-steady-state model, derived on the basis of the coupling, have shown very close results to each other. However, as also previously observed in the literature, the conversion rates of H2 were severely underestimated by the TGA-based kinetic model. Finally, the developed approach was applied to a 300 W CLC reactor, previously experimentally studied at Chalmers University. The agreement with the experimental data was reasonably good, but the reactivity of H2 was higher than that reported in the experiments. The chemistry model source code and simulation configurations are made openly available.</p
Evaluating Net-Zero Energy Buildings and Their Grid Interaction: A Comprehensive Framework for Operational Phase and A Nordic Case Study
No full textThis paper presents a synthesized evaluation framework for assessing Net-Zero Energy Buildings (NZEBs) during their operational phase, with a specific focus on grid interaction under real market conditions. The framework integrates four established Key Performance Indicators (KPIs): Load/Generation Balance, Self-Consumption Rate, Emission Reduction Rate and Cost Reduction Rate – using high-resolution operational data, hourly grid emission factors, and spot prices. Demonstrated through a case study of a large Finnish residential NZEB equipped with a ground-source heat pump and off-site solar PV, the analysis reveals both the potential and limitations of PV-based solutions in cold climates. While the system achieved an 89% annual load/generation balance, hourly analysis showed a 31% self-consumption rate, with most PV production exported during periods of low prices and low emissions. Operational emissions and electricity costs were reduced by 56% and 41%, respectively, compared to a baseline without PV. However, sensitivity analysis indicates that economic outcomes are highly dependent on prevailing market conditions, highlighting the importance of multi-year evaluation. The framework’s parallel KPIs, when used collectively, enable stakeholders to assess trade-offs and guide practical decisions regarding demand-side management, energy storage, and operational strategies. The economic analysis focuses on market exposure, including O&M costs for PV, but excluding investment costs. The framework is flexible and can be applied to NZEBs with various configurations, supporting robust, data-driven decision-making for improved cost-effectiveness and decarbonization
Study of Isolation Improvement of Antenna Arrays for D-band Transceiver
No full textThis paper presents an experimental study evaluating the efficiency of various isolation techniques for antenna arrays in the D-band. The influence of antenna polarizations, the distance between the arrays, presence of absorbing materials and metal shield on isolation is studied. The study demonstrates that isolation of up to 80-85 dB between transmitting and receiving antenna arrays in the D-band can be achieved
Exploring new cellular agriculture-based value chains via an analysis on potential feedstock sources in Finland
No full textThe aim of this study was to examine cellular agriculture-based value chains in Finland with two specific objectives: 1) to estimate the potential of selected Finnish agri-food industry side streams and agri-biomasses as the source of carbon for microbial protein production and 2) to identify the barriers and enabling factors related to four cellular agriculture-based value chains based on the Finnish feedstocks sources for fermentation. By evaluating the carbohydrate content of 13 plant-based biomass streams (molasses, brewers spent grain, distillers spent grain, sugar beet stalk, sugar beet pulp, oat husk, wheat bran, rapeseed cake, potato cell juice, potato peels and residues, potato tops, straw, surplus grass) as a sugar source for fermentation, the total microbial protein production potential was calculated annually at ca. 290 000 and 360 000 tons for precision and biomass fermentation, respectively. Among the agricultural and food industry streams, straw and oat husk biomass could theoretically supply feedstock for 211 000 and 22 000 tons of protein per year by biomass fermentation, respectively. This is a substantial amount, e.g. when considering 120 000 tons of protein needed annual by Finnish population. The qualitative part of the study elaborated barriers and opportunities of the biotechnology-based production processes using four value chain concepts with distinct feedstock source (grass, bran/husk, sawdust and greenhouse residues) as case examples. The qualitative analysis concluded that, in addition to bioprocess development for reducing production costs, key factors for ensuring well-functioning cellular agriculture business models include resolving agricultural feedstock pre-processing and logistics, optimized facility location, and access to renewable energy
Superbases as Organocatalysts in Low Temperature Glycolytic Depolymerization of Polyethylene Terephthalate (PET)
No full textChemical recycling offers a prospective solution for valorizing the vast amount of diverse polyethylene terephthalate (PET) waste generated from various streams. Rigid and flexible packaging such as bottles, and films, or textiles, optionally containing also comonomers like polypropylene terephthalate (PPT) and polybutylene terephthalate (PBT), are essential materials to be considered. In this study, low temperature depolymerization of PET was investigated by implementing glycolysis as the chemical recycling method. In glycolysis of PET, the polymer is depolymerized in excess ethylene glycol and presence of catalyst into bis(2-hydroxyethyl) terephthalate (BHET) monomer. The monomer can be re-utilized as feedstock for the manufacturing of recycled virgin-like PET. Herein we report utilization of novel mTBN guanidine superbase (mixture of two isomers, 7-methyl-1,5,7-triazabicyclo-[4.3.0]non-5-ene & 5-methyl-1,5,7-triazabicyclo-[4.3.0]non-6-ene) as efficient organocatalyst for glycolysis of virgin and post-consumer PET materials. Three guanidine compounds were screened as catalyst under various conditions and their efficiency was compared to zinc acetate, which is a conventionally applied transesterification catalyst. All superbases achieved high PET conversions of over 90 % at low reaction temperature of 140 °C within 2 h, while Zn(OAc) 2 showed only 18 % conversion. Moreover, mTBN superbase was the most efficient by depolymerizing PET powder in just 20 min. Industrially viable conversions of over 90 % resulted in BHET monomer recovery of over 40 % determined by mass. Size-exclusion chromatography (SEC) results indicate that reaction temperature has significant influence on the depolymerization reaction depth. Furthermore, experiments with different PET feedstocks demonstrate the significance of materials’ surface area towards depolymerization efficiency.</p
Mono- and bimetallic platinum-based catalysts in dehydrogenation of perhydro dibenzyltoluene
Get PDFLiquid organic hydrogen carriers (LOHCs) are emerging as solutions for storing renewable hydrogen. A particularly promising LOHC candidate system is dibenzyltoluene (DBT) and its fully hydrogenated form, perhydro dibenzyltoluene (H18-DBT). The dehydrogenation reaction of H18-DBT is critical for the feasibility of the LOHC system, requiring catalysts that are active, resistant towards deactivation, and do not promote the decomposition of the LOHC compound. This study examined the dehydrogenation of H18-DBT using both monometallic Pt-catalysts and bimetallic catalysts composed of Ptsingle bondPd, Ptsingle bondRu and Ptsingle bondRe supported on alumina and titania. The extent of dehydrogenation ranged from 32% to 69% over 45 min in a batch reactor, with a molar ratio of H18-DBT to Pt of 400:1. In the series of Pt-catalysts, the highest quantity of weak acid sites and a moderate amount of medium acid sites exhibited the highest dehydrogenation activity. The bimetallic Ptsingle bondRe catalyst on alumina demonstrated improved efficiency in H18-DBT dehydrogenation, though it did not outperform the most active catalyst, monometallic Pt supported on titania. Notably, the decomposition products of H18-DBT in the hydrogen gas reached concentration of 0.03 wt% within 45 min reaction time
Analysis of elastic and plastic behaviour in untreated pine wood under scratch test loads combining X-ray computed tomography and finite element simulations
No full textWood is an anisotropic material, which affects its performance under different loading conditions. To understand the origin of surface failures occurring in wood under mechanical disintegration loads, an accurate investigation of its elastic and plastic behaviour is required. This study introduces a methodology that integrates experimental scratch testing, X-ray micro-computed tomography (μCT), and finite element simulations to examine the elastic and plastic deformation and failure behaviour of untreated pine wood under scratch loading. In the existing literature, scratch testing is primarily employed to assess coating adhesion or material abrasion resistance; its use for probing the mechanical response of wood remains limited. In the present study, scratches were applied to pine specimens in the radial, tangential, and longitudinal directions of wood using a diamond indenter under constant normal loads perpendicular to the scratched surface. The permanent residual depths measured by μCT were compared with FE-predicted deformations. The selected methodology enables quantification of the relationship between wood structure, loading conditions, and scratch performance. The results demonstrated that the regions with higher density favoured elastic deformation, whereas the residual scratch depth, reflecting plastic deformation, provided a reliable indicator of scratch resistance, exhibiting higher scratch resistance for the higher density wood. In particular, the wood with higher density showed residual depths in the range of 53–144 µm in radial direction scratches, whereas the less dense wood showed values between 90 and 300 µm. μCT imaging also revealed detailed deformation mechanisms and fracture pathways that develop under scratch-type loading. By coupling μCT with FE modelling for wood scratch mechanics, the work deepens the understanding of how wood microstructure responds to different scratch loading conditions. The findings can serve as a scientific reference for future experimental and numerical investigations of scratching, cutting and other disintegration loads in untreated wood and wood-based composites at the microscale.</p