Publications

Conference presentations and posters | 2014

"BioCAT – Clean air technology for small-scale combustion systems"

Reichert G, Wöhler M, Schwabl M, Schmidl C, Aigenbauer S, Bachmaier H, Figl F, Hartmann H, Haslinger W, Kirchhof J, Stressler H, Sturmlechner R, Turowski P, Voglauer B. BioCAT – Clean air technology for small-scale combustion systems, 4. Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria. (oral presentation)

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Conference presentations and posters | 2015

"Investigations on the catalytic activity of bed material coating regarding the water-gas-shift reaction and the steam reforming of model compounds for lighter and heavier hydrocarbons"

Kuba M, Havlik F, Kirnbauer F, Hofbauer H. Investigations on the catalytic activity of bed material coating regarding the water-gas-shift reaction and the steam reforming of model compounds for lighter and heavier hydrocarbons, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (oral presentation)

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Conference presentations and posters | 2020

"Long-term verification of a new modular method for CO-lambda-optimisation"

Zemann C, Hammer F, Gölles M. Long-term verification of a new modular method for CO-lambda-optimisation. 6th Central European Biomass Conference CEBC 2020 (Oral Presentation). 2020.

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Other Publications | 2018

100% ein Zukunftsprojekt; Innovatives Forschungslabor am Technopol Wieselburg

Aigenbauer S, Stadler M, Zellinger M. 100% ein Zukunftsprojekt; Innovatives Forschungslabor am Technopol Wieselburg. TGA Planung 2020. December 2019

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Reports | 2017

2016 Survey of Non-Starch Alcohol and Renewable Hydocarbon Biofuels Producers

Warner E, Bacovsky D, Schwab A. 2016 Survey of Non-Starch Alcohol and Renewable Hydocarbon Biofuels Producers. 2016 Survey of Non-Starch Alcohol and Renewable Hydocarbon Biofuels Producers. February 2017.

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Peer reviewed papers | 2016

2250-h long term operation of a water gas shift pilot plant processing tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant

Kraussler M, Binder M, Hofbauer H. 2250-h long term operation of a water gas shift pilot plant processing tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant. International Journal of Hydrogen Energy. 27 April 2016;41(15): 6247-6258.

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Conference presentations and posters | 2012

2nd Generation Biofuels from Biomass by steam gasification

Rauch R. 2nd Generation Biofuels from Biomass by steam gasification, 1. Nürnberger Fach-Kolloquium Methanisierung und Second Generation Fuels 2012, 29th-30th of May 2012, Nürnberg, Germany.

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Peer reviewed papers | 2011

A carbon-cycle-based stochastic cellular automata climate model

Lichtenegger K, Schappacher W. A carbon-cycle-based stochastic cellular automata climate model. International Journal of Modern Physics C. 2011;22(6):607-621.

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In this paper a stochastic cellular automata model is examined, which has been developed to study a "small" world, where local changes may noticeably alter global characteristics. This is applied to a climate model, where global temperature is determined by an interplay between atmospheric carbon dioxide and carbon stored by plant life. The latter can be released by forest fires, giving rise to significant changes of global conditions within short time.

Other papers | 2009

A cell agglomeration algorithm for accelerating detailed chemistry. In: Combustion Theory and Modelling

Goldin GM, Ren Z, Zahirovic S. A cell agglomeration algorithm for accelerating detailed chemistry in CFD. Combustion Theory and Modelling. 2009;13(4):721-39.

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A cell agglomeration algorithm is proposed to mitigate the computational cost of incorporating detailed chemical kinetics in multi-dimensional Computational Fluid Dynamics (CFD) simulations. Cells that are close in species and energy composition space are agglomerated before calling the reaction integrator, substantially reducing the number of chemistry integrations. The algorithm is generalized and applicable to any reacting flow configuration, and the accuracy is fully controllable. A dynamic hash table is used to efficiently bin cells into high dimensional hyper-cubes in composition space. The method is applied to four different CFD simulations and the speed-up and incurred error are assessed for a range of agglomeration tolerances and table dimensions. The proposed approach exhibits up to an order of magnitude speed-up with a relatively moderate decrease in accuracy.

Peer reviewed papers | 2012

A CFD model for thermal conversion of thermally thick biomass particles

Mehrabian R, Zahirovic S, Scharler R, Obernberger I, Kleditzsch S, Wirtz S, et al. A CFD model for thermal conversion of thermally thick biomass particles. Fuel Process Technol. 2012;95:96-108.

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A one-dimensional model for the thermal conversion of thermally thick biomass particles is developed for the simulation of the fuel bed of biomass grate furnaces. The model can be applied for cylindrical and spherical particles. The particle is divided into four layers corresponding to the main stages of biomass thermal conversion. The energy and mass conservation equations are solved for each layer. The reactions are assigned to the boundaries. The model can predict the intra-particle temperature gradient, the particle mass loss rate as well as the time-dependent variations of particle size and density, as the most essential features of particle thermal conversion. When simulating the fuel bed of a biomass grate furnace, the particle model has to be numerically efficient. By reducing the number of variables and considering the lowest possible number of grid points inside the particle, a reasonable calculation time of less than 1 min for each particle is achieved. Comparisons between the results predicted by the model and by the measurements have been performed for different particle sizes, shapes and moisture contents during the pyrolysis and combustion in a single-particle reactor. The results of the model are in good agreement with experimental data which implies that the simplifications do not impair the model accuracy.

Conference presentations and posters | 2019

A CFD-method for the analysis and optimization of the fixed bed conversion in biomass grate furnaces

Singer M, Gruber T, Mehrabian R, Scharler R. A CFD-method for the analysis and optimization of the fixed bed conversion in biomass grate furnaces. 27th European Biomass Conference & Exhibition (Poster). 2019.

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To optimize the combustion of biomass grate furnaces a sensitivity analysis is carried out by means of CFD simulation. The methodical procedure consists of a 3D packed bed biomass combustion model, which describes the most essential characteristics of the thermal conversion of biomass particles, such as the detailed consideration of drying, pyrolysis and char oxidation in parallel processes. Within the sensitivity analysis the following parameters have been investigated: distribution of false air, residence time of fuel on the grate and distribution of recirculated flue gas and primary air below the grate. To evaluate the influence of the varied parameters on the combustion process the focus lied on the position of the thermal conversion of the biomass and the CO at the outlet of the simulation domain. The results of the sensitivity analysis show a shift of the thermal conversion towards the grate end for increased false air as well as for reduced momentum of primary air/recirculated flue gas mixture. An increase of the fuel residence time leads to a shift of the thermal conversion towards the fuel inlet. Consequently a large region of the primary combustion zone is not used due to earlier release of CO inside the fuel bed.

PhD Thesis | 2022

A control strategy for optimising the operational behaviour of biomass boilers

Zemann C. A control strategy for optimising the operational behaviour of biomass boilers. 2022. 225 S.

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Biomassefeuerungen spielen eine Schlüsselrolle in der Energiewende hin zu einem vollständig erneuerbaren Energiesystem. Allerdings müssen sie sich zukünftigen Herausforderungen stellen, um weiterhin relevant zu bleiben. Einerseits müssen Biomassefeuerungen mit dem höchstmöglichen Wirkungsgrad arbeiten, um wirtschaftlich rentabel zu bleiben während sie gleichzeitig eine hohe Lastmodulationsfähigkeit aufweisen müssen, um für eine breitere Palette von Anwendungen eingesetzt werden zu können. Andererseits müssen Biomassefeuerungen immer strengere Grenzwerte für Schadstoffemissionen einhalten und gleichzeitig in der Lage sein, neue und alternative Biomassebrennstoffe mit geringerer Qualität zu verbrennen.

In dieser Arbeit wird eine modellbasierte Regelungsstrategie entwickelt, die es Biomassefeuerungen ermöglicht, all diese Herausforderungen zu meistern. Diese Regelungsstrategie besteht aus drei Teilen, einer Verbrennungsregelung, einem Zustands- und Parameterschätzer und einer Methode zur CO-lambda-Optimierung. Alle drei Teile werden in dieser Arbeit hergeleitet und im Detail diskutiert, insbesondere im Hinblick auf ihre Implementierung an realen Biomassefeuerungen. Darüber hinaus werden alle drei Teile der modellbasierten Regelungsstrategie durch Simulationsstudien sowie durch eine Implementierung in realen Biomassefeuerungen verifiziert.

Als Grundlage für die modellbasierte Regelungsstrategie wird ein mathematisches Modell abgeleitet, welches das dynamische Verhalten der Prozesse in der Biomassefeuerungen einschließlich des Einflusses der Brennstoffeigenschaften beschreibt. Die berücksichtigten Brennstoffeigenschaften sind die Schüttdichte und die chemische Zusammensetzung einschließlich des Wasser- und Aschegehalts sowie der untere Heizwert.

Die Verbrennungsregelung nutz die Stellglieder der Biomassefeuerung um dessen stabilen Betrieb zu gewährleisten und schnelle Laständerungen zu ermöglichen. Diese modellbasierte Regelstrategie berücksichtigt durch ihre Formulierung, die auf dem oben genannten mathematischen Modell basiert, explizit alle relevanten Brennstoffeigenschaften. Dadurch reagiert sie gezielt auf Änderungen dieser Brennstoffeigenschaften und kompensiert direkt deren Einfluss auf den Betrieb der Biomassefeuerung. Gleichzeitig weist sie eine einfache Struktur auf und ist daher leicht zu implementieren und zu warten. Diese modellbasierte Verbrennungsregelung wird sowohl in Simulationsstudien als auch durch Experimente nach einer Implementierung an einer realen Biomassefeuerung verifiziert.

Es wird ein kombinierter Zustands- und Parameterschätzer entwickelt, der gleichzeitig die Brennstoffeigenschaften, die anschließend von der Verbrennungsregelung verwendet werden, und die Zustandsgrößen der Biomassefeuerungen in Echtzeit schätzt. Er basiert auf einem erweiterten Kalman-Filter, der das in dieser Arbeit vorgestellte mathematische Modell verwendet. Diese Methode wird für verschiedene Brennstoffeigenschaften sowohl in Simulationsstudien als auch durch Messdaten aus realen Biomassefeuerungen verifiziert. Die Ergebnisse dieser Verifikation zeigen, dass diese Methode in der Lage ist, die Brennstoffeigenschaften und Zustandsgrößen auch bei Last- oder Brennstoffwechseln genau zu bestimmen.

Um einen Betrieb der Biomassefeuerung mit möglichst hohem Wirkungsgrad und möglichst geringen Schadstoffemissionen zu gewährleisten, wird eine Methode zur CO-lambda-Optimierung entwickelt. Diese Methode verwendet einen erweiterten Kalman-Filter in Kombination mit Messdaten des Sauerstoffgehalts und des CO-Gehalts des Rauchgases zur Bestimmung eines optimalen Luftüberschussverhältnisses für den aktuellen Zustand der Biomassefeuerung. Diese Methode wird an einer realen Biomassefeuerung in einer Langzeitvalidierung über mehrere Monate verifiziert und validiert. Während dieser Langzeitvalidierung führte die Anwendung dieser Methode zur CO-lambda-Optimierung zu einer Wirkungsgradsteigerung von 3,8 %, einer Reduktion der CO-Emissionen um durchschnittlich 200 mg/m³ sowie einer Verringerung der Gesamtstaubemissionen um durchschnittlich 19 %.

Zusammenfassend ermöglicht die in dieser Arbeit vorgestellte modellbasierte Regelungsstrategie es, Biomassefeuerungen mit den geringstmöglichen Schadstoffemissionen und dem höchstmöglichen Wirkungsgrad zu betreiben und dabei ein hohes Maß an Brennstoffflexibilität und Lastmodulationsfähigkeit zu erreichen. Darüber hinaus weist die Regelungsstrategie eine geringe Komplexität auf und ist leicht in realen Biomassefeuerungen zu implementieren und zu warten. Dies ermöglicht den breiten Einsatz dieser Regelungsstrategie an bestehenden und zukünftigen Biomassefeuerungen. Dies unterstützt die weitere Verbreitung von Biomassefeuerungen im Energiesystem, was zur Reduzierung der CO2e-Emissionen beiträgt und auch die verstärkte Nutzung anderer, volatiler erneuerbarer Technologien, wie z.B. solarthermischer Anlagen, ermöglicht.

Other Publications | 2018

A flexible low cost PV/EV microgrid controller concept based on a Raspberry Pi

Stadler M. A flexible low cost PV/EV microgrid controller concept based on a Raspberry Pi. Working Paper, Center for Energy and innovative Technologies (CET) and Bioenergy 2020+ GmbH, June 2018.

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Peer reviewed papers | 2017

A Generalization of Ackermann’s Formula for the Design of Continuous and Discontinuous Observers

Anca-Couce A, Sommersacher P, Scharler R. Online experiments and modelling with a detailed reaction scheme of single particle biomass pyrolysis. Journal of Analytical and Applied Pyrolysis. Available online 17 July 2017

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Detailed reaction schemes and experimental data for the online release of pyrolysis volatiles are required to gain a more fundamental understanding of biomass pyrolysis, which would in turn allow the process to be controlled in a more precise way and the development of more targeted applications. A detailed online characterisation of pyrolysis products has been conducted in single particle experiments with spruce pellets at different temperatures, obtaining a good closure of the elemental mass balances. The yields and online release of CO, CO2, H2O, CH4, other light hydrocarbons and total organic condensable species, as well as char yield and composition, can be predicted with a reasonable accuracy with the application of a single particle model, coupled with a detailed pyrolysis scheme, and a simple one-step scheme for tar cracking. In order to achieve it, improvements have been conducted in the pyrolysis scheme, mainly concerning the release of light hydrocarbons and char yield and composition. Deviations are still present in the different groups in which organic condensable species can be classified.

Other papers | 2019

A Generalization of Ackermann’s Formula for the Design of Continuous and Discontinuous Observers

Niederwieser H, Koch S, Reichhartinger M. A Generalization of Ackermann’s Formula for the Design of Continuous and Discontinuous Observers. 58th IEEE Conference on Decision and Control. 2019.

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This paper proposes a novel design algorithm for nonlinear state observers for linear time-invariant systems. The approach is based on a well-known family of homogeneous differentiators and can be regarded as a generalization of Ackermann's formula. The method includes the classical Luenberger observer as well as continuous or discontinuous nonlinear observers, which enable finite time convergence. For strongly observable systems with bounded unknown perturbation at the input the approach also involves the design of a robust higher order sliding mode observer. An inequality condition for robustness in terms of the observer gains is presented. The properties of the proposed observer are also utilized in the reconstruction of the unknown perturbation and robust state-feedback control

Peer reviewed papers | 2019

A generally applicable, simple and adaptive forecasting method for the short-term heat load of consumers

Nigitz T, Gölles M. A generally applicable, simple and adaptive forecasting method for the short-term heat load of consumers. Applied Energy 2019;241:73-81.

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Energy management systems aiming for an efficient operation of hybrid energy systems with a high share of different renewable energy sources strongly benefit from short-term forecasts for the heat-load. The forecasting methods available in literature are typically tailor-made, complex and non-adaptive. This work condenses these methods to a generally applicable, simple and adaptive forecasting method for the short-term heat load. From a comprehensive literature review as well as the analysis of measurement data from seven different consumers, varying in size and type, the ambient temperature, the time of the day and the day of the week are deduced to be the most dominating factors influencing the heat load. According to these findings, the forecasting method bases on a linear regression model correlating the heat load with the ambient temperature for each hour of the day, additionally differentiating between working days and weekend days. These models are used to predict the future heat load by using forecasts for the ambient temperature from weather service providers. The model parameters are continuously updated by using historical data for the ambient temperature and the heat load, i.e. the forecasting method is adaptive. Additionally, the current prediction error is used to correct the prediction for the near future. Due to their simplicity, all necessary steps of the forecasting method, the update of the model parameters, the prediction based on linear regression models and the correction, can be implemented and computed with little effort. The final evaluation with measurement data from all seven consumers investigated leads to a Mean Absolute Range Normalized Error (MARNE) of 2.9% on average, and proves the general applicability of the forecasting method. In summary, the forecasting method developed is generally applicable, simple and adaptive, making it suitable for the use in energy management systems aiming for an efficient operation of hybrid energy systems.

Peer reviewed papers | 2018

A higher-order generalization of the NPK-method.

Birkelbach F, Deutsch M, Flegkas S, Winter F, Werner A. A higher-order generalization of the NPK-method. Thermochimica Acta, 9 January 2018;661:27-33.

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A novel algorithm to identify the full kinetic model of solid state reactions according to the General Kinetic Equation is presented. It is a higher-order generalization of the Non-Parametric Kinetics method (NPK-method) and allows for the simultaneous identification of the conversion, temperature and pressure dependency from any combination of measurements. As a model-free identification method, it does not rely on a-priori assumptions about the kinetic model. The result vectors can be used to identify the kinetic parameters by means of model fitting for each variable independently.

The steps of the algorithm are described and its effectiveness is demonstrated by applying it to simulated datasets. The kinetic parameters could be recovered very accurately from the test data, also in the presence of noise.

Overall the higher order NPK-method is a very promising approach to derive kinetic models from experimental data with a minimum of a-priori assumptions about the reaction.

Peer reviewed papers | 2017

A hybrid of winddiesel technology with biomass-based Fischer-Tropsch synthesis

Nikparsa P, Rauch R, Mirzaei AA. A hybrid of winddiesel technology with biomass-based Fischer-Tropsch synthesis. Monatshefte für Chemie. 10 July 2017;1-10.

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The syngas mixture produced from biomass (bio-syngas) is characterized by a H2/CO molar ratio of 1.5 in this work, which is different from that of traditional syngas ratio of 2. Therefore a hybrid of winddiesel technology with bio-syngas conversion by Fischer–Tropsch synthesis (WD-FT) on a cobalt based catalyst was investigated, for the first time, using a slurry reactor. The result from feeding this technology is compared with the direct converting biomass derived synthetic gas to fuels via Fischer–Tropsch synthesis (BS-FT). Experiments were performed at different syngas composition (variation of H2/CO ratio), keeping the other parameters (temperature 230 °C; gas flow 5 Nm³/h, pressure 20 bar) constant. Comparison of the WD-FT with the BS-FT synthesis results displayed mass fraction of light hydrocarbons and higher catalytic stability and activity after 500 h. The olefin structures for the different product distributions, obtained from different reactions, are determined by ¹H NMR spectroscopy. Negligible amounts of iso-α-olefins were detected in the product of the WD-FT reaction. In the case of the alpha value, a slight change was observed between 0.93 and 0.92 for the BS-FT and WD-FT reaction.
 

Peer reviewed papers | 2020

A MILP-based modular energy management system for urban multi-energy systems: Performance and sensitivity analysis

Moser AGC, Muschick D, Gölles M, Nageler PJ, Schranzhofer H, Mach T et al. A MILP-based modular energy management system for urban multi-energy systems: Performance and sensitivity analysis. Applied Energy. 2020;2020(261). 114342.

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The continuous increase of (volatile) renewable energy production and the coupling of different energy sectors such as heating, cooling and electricity have significantly increased the complexity of urban energy systems. Such multi-energy systems (MES) can be operated more efficiently with the aid of optimization-based energy management systems (EMS). However, most existing EMS are tailor-made for one specific system or class of systems, i.e. are not generally applicable. Furthermore, only limited information on the actual savings potential of the usage of an EMS under realistic conditions is available. Therefore, this paper presents a novel modular modeling approach for an EMS for urban MES, which also enables the modeling of complex system configurations. To assess the actual savings potential of the proposed EMS, a comprehensive case study was carried out. In the course of this the influence of different user behavior, changing climatic conditions and forecast errors on the savings potential was analyzed by comparing it with a conventional control strategy. The results showed that using the proposed EMS in conjunction with supplementary system components (thermal energy storage and battery) an annual cost savings potential of between 3 and 6% could be achieved.

Conference presentations and posters | 2020

A modular energy management system for multi-energy systems

Muschick D, Kaisermayer V, Moser A, Gölles M. A modular energy management system for multi-energy systems. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

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Peer reviewed papers | 2022

A multi-layer model of stratified thermal storage for MILP-based energy management systems

Muschick D, Zlabinger S, Moser A, Lichtenegger K, Gölles M. A multi-layer model of stratified thermal storage for MILP-based energy management systems. Applied Energy. 2022 May 15;315.118890. https://doi.org/10.1016/j.apenergy.2022.118890

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Both the planning and operation of complex, multi-energy systems increasingly rely on optimization. This optimization requires the use of mathematical models of the system components. The model most often used to describe thermal storage, and especially in the common mixed-integer linear program (MILP) formulation, is a simple integrator model with a linear loss term. This simple model has multiple inherent drawbacks since it cannot be applied to represent the temperature distribution inside of the storage unit. In this article, we present a novel approach based on multiple layers of variable size but fixed temperature. The model is still linear, but can be used to describe the most relevant physical phenomena: heat losses, axial heat transport, and, at least qualitatively, axial heat conduction. As an additional benefit, this model makes it possible to clearly distinguish between heat available at different temperatures and thus suitable for different applications, e.g., space heating or domestic hot water. This comes at the cost of additional binary decision variables used to model the resulting hybrid linear dynamics, requiring the use of state-of-the-art MILP solvers to solve the resulting optimization problems. The advantages of the more detailed model are demonstrated by validating it against a standard model based on partial differential equations and by showing more realistic results for a simple energy optimization problem.

Other papers | 2013

A new innovative CFD-based optimisation method for biomass combustion plants

Shiehnejadhesar A, Schulze K, Scharler R, Obernberger I. A new innovative CFD-based optimisation method for biomass combustion plants. Biomass Bioenergy. 2013;53:48-53.

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In this paper, the work on the development and test of a basic design tool for the automatic performance of parameter studies for the optimisation of biomass combustion plants is presented. The model consists of parameterisation and optimisation routines linked with an in-house developed empirical packed bed combustion model as well as gas phase CFD models especially adapted for biomass grate furnaces. To test and verify the routine developed, it has been applied to the optimisation of a 180 kWth pilot-scale grate furnace. The main focus was on the minimisation of CO emissions and the pressure loss by changing the diameter and angle of the secondary air nozzles. The simulation results show that the time of the optimisation process can be reduced considerably by the automatic routine developed and the evaluation of several independent design parameters is possible. This new procedure forms an important milestone towards automatic CFD-based furnace and boiler optimisations in the future. © 2013 Elsevier Ltd.

Other papers | 2017

A novel approach for the implementation of TORrefaction in Residential and COMmunal heating Boilers (TORRECOMB)

Kourkoumpa DS, Kienzl N, Isemin R, Strasser C, Nikolopoulus N, Margaritis N, Panagiotis G. A novel approach for the implementation of TORrefaction in Residential and COMmunal heating Boilers (TORRECOMB). 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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Peer reviewed papers | 2020

A novel production route and process optimization of biomass-derived paraffin wax for pharmaceutical application

Gruber H, Lindner L, Arlt S, Reichhold A, Rauch R, Weber G, Trimbach J, Hofbauer H. A novel production route and process optimization of biomass-derived paraffin wax for pharmaceutical application. Journal of Cleaner Production. 2020;275:124135

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The Biomass to Liquid (BtL) Fischer-Tropsch (FT) route converts lignocellulosic feedstock to renewable hydrocarbons. This, paper shows a novel production route for biomass-derived synthetic paraffin wax via gasification of lignocellulosic feedstock, Fischer-Tropsch synthesis (FTS) and hydrofining. The Fischer-Tropsch wax was fractionated, refined and analyzed with respect to compliance to commercial standards. The fractioned paraffin waxes were hydrofined using a commercial sulfide NiMo–Al2O3 catalyst and a trickle bed reactor. A parametric variation was performed to optimize the hydrofining process. It was shown that the produced medium-melt paraffin wax could fulfill the requirements for “Paraffinum solidum” defined by the European Pharmacopoeia (Ph. Eur). The high-melt wax fraction showed potential to be used as food packaging additive. Furthermore, the renewable wax was analyzed regarding PAH content and it was shown that the hydrofined wax was quasi-PAH-free.

Conference presentations and posters | 2021

A platform for energy management in communities

Derflinger N, Zellinger M. A platform for energy management in communities. ComForEn 2021 11. Symposium Communications for Energy Systems. 23 November 2021.

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Peer reviewed papers | 2019

A practical field trial to assess the potential of Sida hermaphrodita as a versatile, perennial bioenergy crop for Central Europe.

von Gehren P, Gansberger M, Pichler W, Weigl M, Feldmeier S, Wopienka E, Bochmann G. A practical field trial to assess the potential of Sida hermaphrodita as a versatile, perennial bioenergy crop for Central Europe. Biomass and Bioenergy 2019;122:99-108.

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Due to high biomass accumulation ability and multiple ecological benefits, the versatile, perennial bioenergy crop Sida hermaphrodita has sparked the interest of researchers in Central Europe. We assessed the crop's agronomy and bioenergy potential when grown under Austrian climate and soil conditions. A field trial was established in Austria, where the factors planting density and utilization strategy (thermal or biogas) were monitored for three growing seasons. Harvesting lignified biomass for thermal utilization at the end of the growing period resulted in higher dry matter yields than green biomass for biogas utilization which was harvested with a two-cut strategy. Due to lower costs but similar yield, a planting density of 1.77 plants m-2 is preferable over 2.66 plants m-2. The pelletizing process of the biomass was analyzed iteratively in 20 runs to optimize the energy efficiency and process stability while simultaneously increasing pellet durability. A simple drying step, disintegration with a pan grinder mill and pelletizing using a flat die pellet press resulted in stable, high quality pellets. Fuel characteristics of the biomass were favorable and all requirements to be categorized as solid biofuel were met, while combustion tests showed a good applicability of the produced pellets. When green biomass was used for biogas production, a significant drop in methane yield could be noted from the second growing season onward, indicating that older plants are less suitable for biogas production. Our results hint towards the potential of lignified S. hermaphrodita biomass to be used as a solid fuel for energy production.

Peer reviewed papers | 2021

A review on bed material particle layer formation and its positive influence on the performance of thermo-chemical biomass conversion in fluidized beds

Kuba M, Skoglund N, Öhman M, Hofbauer H. A review on bed material particle layer formation and its positive influence on the performance of thermo-chemical biomass conversion in fluidized beds.Fuel.2021.291:120214. https://doi.org/10.1016/j.fuel.2021.120214

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Bed material particle layer formation plays a significant role in thermo-chemical conversion of biomass. The interaction between biomass ash and bed material in fluidized bed conversion processes has been described for a variety of different applications and spans from fundamental research of formation mechanisms to effects of this layer formation on long-term operation in industrial-scale. This review describes the current state of the research regarding the mechanisms underlying layer formation and the positive influence of bed material particle layer formation on the operation of thermo-chemical conversion processes. Thus, the main focus lies on its effect on the catalytic activity towards gasification reactions and the impact on oxygen transport in chemical looping combustion. The review focuses on the most commonly investigated bed materials, such as quartz, feldspar or olivine. While the most relevant results for both the underlying mechanisms and the subsequently observed effects on the operation are presented and discussed, knowledge gaps where further research is necessary are identified and described.

Other papers | 2017

A Theoretical and Experimental Study of the Formation of Aromatic Hydrocarbons (BTX/PAH) as Soot Precursors from Biomass Pyrolysis Products

Mehrabian R, Shiehnejadhesar A, Bahramian H, Anca-Couce A, Sommersacher P, Hochenauer C, Scharler R. A Theoretical and Experimental Study of the Formation of Aromatic Hydrocarbons (BTX/PAH) as Soot Precursors from Biomass Pyrolysis Products. 25th European Biomass Conference & Exhibition (oral presentation). May 2017, Stockholm, Sweden.

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In this work a novel reaction mechanism for gas phase reactions has been developed to predict the formation of aromatic compounds from the pyrolysis products of woody biomass particles. The aromatic compounds are important for being main soot precursors as well as their toxic properties. The developed gas phase mechanism is validated with experimental data from literature as well as experimental data performed with a single particle reactor for three different pyrolysis temperatures, namely 550, 800 and 1000°C. A good agreement is achieved between model results and experimental data for the total yield of each main family of aromatic hydrocarbons, i.e. phenolics, BTXs and PAHs.

Other Publications | 2012

Abbilden des instationären Betriebs eines Pelletkessel durch Messung und Simulation

Schnetzinger, R. Abbilden des instationären Betriebs eines Pelletkessel durch Messung und Simulation, Diploma Thesis, FH Oberösterreich, Wels, Austria, 2012.

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This thesis focuses on portraying the thermal behavior of a biomass pellet boiler through measurement and simulation. During operation the power of a pellet boiler changes depending on the heat demand. Detailed measurements were conducted to record this changing behavior of some boilers and estimate their levels of efficiencies. Subsequently a mathematical model was created to emulate boilers and their thermal performance without such measurements. The first part of this thesis deals with the description of the simulation model and the measurements which were carried out. Secondly, the verification of the model is discussed. For this verification simulation results of three different boilers are compared to measurement data and pictured in various diagrams. The last part of this thesis is about further simulations of these three boilers where the control units were emulated too. The model was built in the MATLAB/Simulink® environment and is generally based on
thermodynamic relationships and heat balances in a boiler. However, through constant comparison of the simulation results with the measurement data some parameters were adapted to fit the simulation to reality. Therefore this model is “semi-empirical” as physical correlations are included but some parameters were deduced from measurement. Following, the verification of the model is discussed through the comparison of measurement data and simulation results. For the verifications the boiler power, fuel mass flow as well as
the heat consumption were taken from the measurement data and set as input for the simulation. The calculated results show that the boiler model enables to portray the thermal behavior of the three boilers tested with only small divergences. At the end of this thesis it was attempted to model the control unit of the three boilers by analyzing the measurement data. Having a model for the control unit, the inputs from the measurement data are reduced to just two variables, the water inlet temperature and the water volume flow (heat consumption). The comparison of the calculated values to the measurement data shows slightly higher divergences than during the validation, especially where the simulated control unit does not behave like the real one. Through the simulation of further boilers the model could be continuously enhanced. In the future this “virtual boiler” should be used to test control algorithms of boiler control units to enhance their efficiencies.

Conference presentations and posters | 2017

Abschätzung der Ertragssteigerung durch moderne Regelungsstrategien

Innerhofer P, Unterberger V, Gerardts B, Lichtenegger K, Gölles M. Abschätzung der Ertragssteigerung durch moderne Regelungsstrategien. 27. Symposium Thermische Solarenergie OTTI. Bad Staffelstein, Deutschland: 2017.

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Peer reviewed papers | 2017

Acid base interaction and its influence on the adsorption kinetics and selectivity order of aromatic sulfur heterocycles adsorbing on Ag-Al2O3

Neubauer R, Husmann M, Weinlaender C, Kienzl N, Leitner E, Hochenauer C. Acid base interaction and its influence on the adsorption kinetics and selectivity order of aromatic sulfur heterocycles adsorbing on Ag-Al2O3. Chemical Engineering Journal. 1 February 2017;309: 840-849.

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Adsorptive desulfurization is a promising technology to provide sulfur free fuels for fuel cell based power units. In this work the adsorption kinetics of three different aromatic sulfur heterocycles was studied for Ag-Al2O3. The influence of individual as well as competitive adsorption on the selectivity order was investigated by equilibrium and breakthrough experiments. In these experiments a jet-A1 fuel enriched with benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was used. The adsorption of aromatic sulfur heterocycles on Ag-Al2O3 proceeds via three different adsorption mechanisms. Within these mechanisms the π-interaction (π-Ag) and the direct sulfur-silver interaction (S-Ag) are significantly stronger in comparison to the acid base interaction (S-H). The results showed that the π-Ag and S-Ag interactions are the major adsorption mechanisms in the first stage, where film-diffusion limits the adsorption rate. In the second stage, the S-H interaction plays only an important role for BT, where intraparticle diffusion is the rate controlling step. The overall selectivity order was found to be BT > DBT > 4,6-DMDBT in the case of competitive adsorption for both equilibrium and breakthrough performance. The S-H contribution was related to incorporation of silver into blank γ-alumina, which significantly increased the overall acidity of the adsorbent.

Other Publications | 2023

Act4Value - Actors for innovative and regional bio residue valorization

Sedlmayer I, Wopienka E. Act4Value - Actors for innovative and regional bio residue valorization. BEST Center Day. 28 June 2023

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A drastic reduction in the consumption of fossil resources and efficient use are key factors in limiting the further progression of climate change. Cascading use and recycling of residues in the sense of bioeconomy and circular economy are essential. Thermochemical or microbiological conversion can produce various intermediates and endproducts (e.g. biochar, basic chemicals, bioenergy) from biogenic residues. Implemented decentrally, such concepts can reduce transportation efforts, increase the degree of self-sufficiency with raw materials, increase regional added value creation and close (preferably regional) material and energy cycles.

Conference presentations and posters | 2014

Active condensation in a 10MW heating plant - measurement results from the first heating season

Hebenstreit B, Höftberger E, Schwabl M, Lundgren J, Toffolo A. Active condensation in a 10MW heating plant - measurement results from the first heating season, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

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Other papers | 2012

Acute systemic and lung inflammation in C57Bl/6J mice after intratracheal aspiration of particulate matter from small-scale biomass combustion appliances based on old and modern technologies

Uski OJ, Happo MS, Jalava PI, Brunner T, Kelz J, Obernberger I, Jokiniemi J, Hirvonen M-R. Acute systemic and lung inflammation in C57Bl/6J mice after intratracheal aspiration of particulate matter from small-scale biomass combustion appliances based on old and modern technologies. Inhalation Toxicology. 2012;24(14):952-965.

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Peer reviewed papers | 2015

Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield

Gruber-Brunhumer MR, Jerney J, Zohar E, Nussbaumer M, Hieger C, Bochmann G, Schagerl M, Obbard JP, Fuchs W, Drosg B. Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield. Algal Research. 01 November 2015;12:230-238.

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Conference presentations and posters | 2018

Adaptive forecasting methods for the prediction of future solar yield of solar thermal plants and heat demand of consumers

Unterberger V, Nigitz T, Luzzu M, Innerhofer P, Muschick D, Gölles M. Adaptive forecasting methods for the prediction of future solar yield of solar thermal plants and heat demand of consumers. 5th International Solar District Heating Conference SDH. Graz, Austria: 2018.

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Other papers | 2018

Adaptive Methods for Energy Forecasting of Production and Demand of Solar Assisted Heating Systems

Unterberger V, Nigitz T, Luzzu M, Muschick D, Gölles M. Adaptive Methods for Energy Forecasting of Production and Demand of Solar Assisted Heating Systems., Proceeding of Papers Vol1, p170-181 International conference on time series and forecasting, Granada, Spain, September 19-21, 2018.

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Books / Bookchapters | 2019

Adaptive Methods for Energy Forecasting of Production and Demand of Solar-Assisted Heating Systems

Unterberger V, Nigitz T, Luzzu M, Muschick D, Gölles M. Adaptive Methods for Energy Forecasting of Production and Demand of Solar-Assisted Heating Systems. In: Valenzuela O, Rojas F, Pomares H, Rojas I. (eds) Theory and Applications of Time Series Analysis. ITISE 2018. Contributions to Statistics. Springer, Cham. 2019.

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Solar-assisted heating systems use the energy of the sun to supply consumers with renewable heat and can be found all over the world where heating of buildings is necessary. For these systems, both heat production and heat demand are directly related to the weather conditions. In order to optimally plan production, storage, and consumption, forecasts for both the future heat production of the thermal solar collectors as well as the future heat demand of the connected consumers are essential. For this reason, this contribution presents adaptive forecast methods for the solar heat production and the heat demand of consumers using weather forecasts. The developed methods are easy to implement and therefore practically applicable. The final verification of the methods shows good agreement between the predicted values and measurement data from a representative solar-assisted heating system.

Peer reviewed papers | 2016

Adsorptive Desulfurization: Fast On-Board Regeneration and the Influence of Fatty Acid Methyl Ester on Desulfurization and in Situ Regeneration Performance of a Silver-Based Adsorbent

Neubauer R, Weinlaender C, Kienzl N, Schroettner H, Hochenauer C. Adsorptive Desulfurization: Fast On-Board Regeneration and the Influence of Fatty Acid Methyl Ester on Desulfurization and in Situ Regeneration Performance of a Silver-Based Adsorbent. Energy and Fuels. 16 June 2016;30(6): 5174-5182.

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Adsorptive on-board desulfurization units require a high desulfurization and regeneration performance for a wide range of fuels to keep them small and ensure long maintenance intervals. A novel thermal regeneration strategy was investigated in this work, fulfilling all requirements for in situ on-board regeneration. In this strategy, a temperature-controlled flow rate (TCFR) of air was used to control the temperature inside the adsorber. With this dynamic approach, the regeneration time was reduced significantly in comparison to other thermal regeneration strategies. The novel regeneration strategy was tested using Ag–Al2O3 as an adsorbent to desulfurize a benzothiophen (BT)-enriched road diesel (300 ppmw of total sulfur). A commercial diesel containing fatty acid methyl ester (FAME) was used to evaluate the fuel flexibility regarding desulfurization and regeneration performance. In the case of 6.63 wt % FAME and 300 ppmw of sulfur, the breakthrough adsorption capacity of sulfur decreased from 1.04 to 0.17 mg/g. In TCFR regeneration experiments, the breakthrough adsorption capacity was restored to over 94% in the case of both fuels. Thereby, the Brunauer–Emmett–Teller (BET) surface area of the regenerated adsorbent decreased by only 1.5%, and negligible carbon deposits were detected.

Peer reviewed papers | 2018

Adsorptive on-board desulfurization over multiple cycles for fuel-cell-based auxiliary power units operated by different types of fuels

Neubauer, R, Weinlaender C, Kienzl N, Bitschnau B, Schroettner H, Hochenauer C. Adsorptive on-board desulfurization over multiple cycles for fuel-cell-based auxiliary power units operated by different types of fuels. Journal of Power Sources. 1 May 2018, 385: 45-54.

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On-board desulfurization is essential to operate fuel-cell-based auxiliary power units (APU) with commercial fuels. In this work, both (i) on-board desulfurization and (ii) on-board regeneration performance of Ag-Al2O3 adsorbent is investigated in a comprehensive manner. The herein investigated regeneration strategy uses hot APU off-gas as the regeneration medium and requires no additional reagents, tanks, nor heat exchangers and thus has remarkable advantages in comparison to state-of-the-art regeneration strategies. The results for (i) show high desulfurization performance of Ag-Al2O3 under all relevant operating conditions and specify the influence of individual operation parameters and the combination of them, which have not yet been quantified. The system integrated regeneration strategy (ii) shows excellent regeneration performance recovering 100% of the initial adsorption capacity for all investigated types of fuels and sulfur heterocycles. Even the adsorption capacity of the most challenging dibenzothiophene in terms of regeneration is restored to 100% over 14 cycles of operation. Subsequent material analyses proved the thermal and chemical stability of all relevant adsorption sites under APU off-gas conditions. To the best of our knowledge, this is the first time 100% regeneration after adsorption of dibenzothiophene is reported over 14 cycles of operation for thermal regeneration in oxidizing atmospheres.

Conference presentations and posters | 2014

Advanced Biofuels Technologies – R&D in Austria

Bacovsky D, Wörgetter M. Advanced Biofuels Technologies – R&D in Austria, Fuels of the Future 2014, 20th-21st of January 2014, Berlin, Germany.

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Conference presentations and posters | 2020

Advanced biomass CCHP (BIO-CCHP) based on gasification, SOFC and cooling machines

Lagler J, Martini S. Advanced biomass CCHP (BIO-CCHP) based on gasification, SOFC and cooling machines. 6th Central European Biomass Conferenc, 2020, Graz.

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Other papers | 2013

Advanced biomass fuel characterisation based on tests with a specially designed lab-reactor

Brunner T, Biedermann F, Kanzian W, Evic N, Obernberger I. Advanced biomass fuel characterization based on tests with a specially designed lab-scale reactor. Energy and Fuels. 2013;27(10):5691-8.

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To examine relevant combustion characteristics of biomass fuels in grate combustion systems, a specially designed lab-scale reactor was developed. On the basis of tests performed with this reactor, information regarding the biomass decomposition behavior, the release of NOx precursor species, the release of ash-forming elements, and first indications concerning ash melting can be evaluated. Within the scope of several projects, the lab-scale reactor system as well as the subsequent evaluation routines have been optimized and tests with a considerable number of different biomass fuels have been performed. These tests comprised a wide variation of different fuels, including conventional wood fuels (beech, spruce, and softwood pellets), bark, wood from short rotation coppice (SRC) (poplar and willow), waste wood, torrefied softwood, agricultural biomass (straw, Miscanthus, maize cobs, and grass pellets), and peat and sewage sludge. The results from the lab-scale reactor tests show that the thermal decomposition behavior and the combustion behavior of different biomass fuels vary considerably. With regard to NOx precursors (NHx, HCN, NO, N2O, and NO2), NH3 and, for chemically untreated wood fuels, also HCN represent the dominant nitrogen species. The conversion rate from N in the fuel to N in NOx precursors varies between 20 and 95% depending upon the fuel and generally decreases with an increasing N content of the fuel. These results gained from the lab-scale reactor tests can be used to derive NOx precursor release models for subsequent computational fluid dynamics (CFD) NOx post-processing. The release of ash-forming vapors also considerably depends upon the fuel used. In general, more than 91% of Cl, more than 71% of S, 1-51% of K, and 1-50% of Na are released to the gas phase. From these data, the potential for aerosol emissions can be estimated, which varies between 18 mg/Nm3 (softwood pellets) and 320 mg/Nm3 (straw) (dry flue gas at 13% O2). Moreover, these results also provide first indications regarding the deposit formation risks associated with a certain biomass fuel. In addition, a good correlation between visually determined ash sintering tendencies and the sintering temperatures of the different fuels (according to ÖNORM CEN/TS 15370-1) could be observed. © 2013 American Chemical Society.

Conference presentations and posters | 2012

Advanced biomass fuel characterisation based on tests with a specially designed lab-scale reactor

Brunner T, Biedermann F, Kanzian W, Evic N, Obernberger I. Advanced biomass fuel characterisation based on tests with a specially designed lab-scale reactor, Conference Impacts of Fuel Quality on Power Production and Environment 2012, 23th-27th of September 2012, Puchberg, Austria.

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To examine relevant combustion characteristics of biomass fuels in grate combustion systems, a specially designed lab-scale reactor was developed. On the basis of tests performed with this reactor, information regarding the biomass decomposition behavior, the release of NOx precursor species, the release of ash-forming elements, and first indications concerning ash melting can be evaluated. Within the scope of several projects, the lab-scale reactor system as well as the subsequent evaluation routines have been optimized and tests with a considerable number of different biomass fuels have been performed. These tests comprised a wide variation of different fuels, including conventional wood fuels (beech, spruce, and softwood pellets), bark, wood from short rotation coppice (SRC) (poplar and willow), waste wood, torrefied softwood, agricultural biomass (straw, Miscanthus, maize cobs, and grass pellets), and peat and sewage sludge. The results from the lab-scale reactor tests show that the thermal decomposition behavior and the combustion behavior of different biomass fuels vary considerably. With regard to NOx precursors (NH3, HCN, NO, N2O, and NO2), NH3 and, for chemically untreated wood fuels, also HCN represent the dominant nitrogen species. The conversion rate from N in the fuel to N in NOx precursors varies between 20 and 95% depending upon the fuel and generally decreases with an increasing N content of the fuel. These results gained from the lab-scale reactor tests can be used to derive NOx precursor release models for subsequent computational fluid dynamics (CFD) NOx post-processing. The release of ash-forming vapors also considerably depends upon the fuel used. In general, more than 91% of Cl, more than 71% of S, 1–51% of K, and 1–50% of Na are released to the gas phase. From these data, the potential for aerosol emissions can be estimated, which varies between 18 mg/Nm3 (softwood pellets) and 320 mg/Nm3 (straw) (dry flue gas at 13% O2). Moreover, these results also provide first indications regarding the deposit formation risks associated with a certain biomass fuel. In addition, a good correlation between visually determined ash sintering tendencies and the sintering temperatures of the different fuels (according to ÖNORM CEN/TS 15370-1) could be observed.

Conference presentations and posters | 2011

Advanced biomass fuel characterisation by the application of dedicated fuel indexes

Brunner T, Moradi F, Obenberger I. Advanced biomass fuel characterisation by the application of dedicated fuel indexes, Central European Biomass Conference 2011, 26th-29th of January 2011, Graz, Austria.

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Other Publications | 2023

Advanced Control ot the Generated Steam in a Municipal Waste Incineration Plant

Niederwieser H, Jäger F, Kirnbauer F, Gölles M. Advanced Control ot the Generated Steam in a Municipal Waste Incineration Plant. BEST Center Day. 28 June 2023

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In modern waste management, the energetic utilization of waste is an important key technology. On the one hand, it allows the waste to be disposed of in an environmentally friendly manner and, on the other hand, makes it possible to reduce the use of other controversial energy sources, such as nuclear fission or fossil fuels. However, the efficient and clean incineration of waste is a challenging task due to the strong inhomogeneity of the waste.

Conference presentations and posters | 2010

Advanced modelling of deposit formation in biomass furnaces – investigation of mechanisms and comparison with deposit measurements in a small-scale pellet boiler

Schulze K, Scharler R, Telian M, Obernberger I. Advanced modelling of deposit formation in biomass furnaces – investigation of mechanisms and comparison with deposit measurements in a small-scale pellet boiler, Impacts of Fuel Quality on Power Generation 2010, 29th of August-3rd of September, Saariselka, Lapland.

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Other papers | 2020

Advanced modular process analysis tool for biomass-based Chemical Looping systems

Steiner T, Schulze K, Scharler R. Advanced modular process analysis tool for biomass-based Chemical Looping systems. 3RD DOCTORAL COLLOQUIUM BIOENERGY. 2020.

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In order to limit global warming to 1.5 °C compared to the pre-industrial temperature level, zero net CO2 emissions are needed on a global scale until 2050. A Chemical Looping (CL) process represents a technological system which is CO2-negative when using biomass as fuel and thus can substantially contribute to this target. In principle, the process uses a metal oxide as oxygen carrier material (OC) which is cyclically oxidized by air or steam and reduced by the fuel. Without air as the direct oxygen source for fuel conversion, high calorific product gases or pure carbon dioxide in case of combustion are obtained after the condensation of water vapor, which can then be stored or further utilized.
Within the funded project ”BIO-LOOP”, different Chemical Looping processes (for example combustion, gasification, hydrogen production) and reactors (fixed bed, fluidized bed) are investigated numerically and experimentally. An advanced process analysis tool based on mass and energy balances of the system considered will be presented. It provides data about the specific internal and external streams, process conditions and efficiencies. Within the analysis tool, various independent modular units describe individual process steps, e.g. mixing, chemical reaction or splitting. These components can be adjusted, combined and interconnected according to the flow chart of the system. The process model represents the first step towards a flexible Chemical Looping reactor simulation toolbox to analyze various process scenarios. Emphasis is put on the flexibility regarding the fuels and oxygen carriers, their conversion and possible process variations. The tool developed will support upcoming CFD modeling and further economic considerations.

Conference presentations and posters | 2012

Advanced Motor Fuels

Bacovsky D. Advanced Motor Fuels, Eco-Mobility Conference 2012, 11th-12th of December 2012, Vienna, Austria.

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Peer reviewed papers | 2021

Advanced Optimal Planning for Microgrid Technologies including Hydrogen and Mobility at a real Microgrid Testbed

Mansoor M, Stadler M, Auer H, Zellinger M. Advanced Optimal Planning for Microgrid Technologies including Hydrogen and Mobility at a real Microgrid Testbed. International Journal of Hydrogen Energy.2021.

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This paper investigates the optimal planning of microgrids including the hydrogen energy system through mixed-integer linear programming model. A real case study is analyzed by extending the only microgrid lab facility in Austria. The case study considers the hydrogen production via electrolysis, seasonal storage and fueling station for meeting the hydrogen fuel demand of fuel cell vehicles, busses and trucks. The optimization is performed relative to two different reference cases which satisfy the mobility demand by diesel fuel and utility electricity based hydrogen fuel production respectively. The key results indicate that the low emission hydrogen mobility framework is achieved by high share of renewable energy sources and seasonal hydrogen storage in the microgrid. The investment optimization scenarios provide at least 66% and at most 99% carbon emission savings at increased costs of 30% and 100% respectively relative to the costs of the diesel reference case (current situation).

Conference presentations and posters | 2020

Advanced Test Methods for Pellet Stoves

Reichert G, Schmidl C. Advanced Test Methods for Pellet Stoves. 6th Central European Biomass Conference, 2020, Graz.

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Conference presentations and posters | 2020

Advanced Test Methods for Pellet Stoves – A Technical Review

Reichert G, Schwabl M, Schmidl C. Advanced Test Methods for Pellet Stoves – A Technical Review. 6th Central European Biomass Conference (oral presentation) 2020.

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Third party testing of direct heating appliances fueled with pellets has been established in many countries worldwide. The main goals are ensuring operation safety and a minimum level of performance of the products prior to market implementation. This kind of approval procedure for new products requires testing standards, certified testing bodies and a legal framework defining minimum requirements for specified performance parameters which are assessed in the respective standards.

While the overall targets are quite similar for all countries having set-up such procedures, the practical implementation of these targets in the national/international testing standards is remarkably different. This applies to both, the way of operating the appliance during the testing and the measurements performed during the testing.

Furthermore several industries were requested recently to modify their product standards towards more realistic operating conditions. The most famous example is car industry, but this request may also apply to biomass heating systems.

 

Conference presentations and posters | 2010

Advanced waste-splitting by sensor based sorting on the example of the MT-plant Oberlaa

Pieber S, Ragossnig A, Brooks L, Meirhofer M, Pomberger R, Curtis A. Advanced waste-splitting by sensor based sorting on the example of the MT-plant Oberlaa, DepoTech 2010, 3rd-5th of November 2010, Leoben, Austria. p 695-698.

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Heterogeneous wastes, which cannot be material-recycled easily are used for energetic utilization. Certain quality criteria need to be met in this context, addressing especially the chlorine content due to the product quality as well as to environmental and safety issues. In regard of current issues in climate policy concerning emission trading, also an increased biogenic content in these waste fractions is desirable. Therefore, experiments with a sensor-based sorting technology at pilot scale as well as large scale have been conducted to analyse the technical feasibility of this technology for its application on heterogeneous wastes to gain products with desired material and quality criteria. The results of pilot scale experiments show that the sensor-based sorting technology is generally technically feasible to gain waste fractions with the required characteristics, if the technology was adjusted to the specific waste stream. Due to restrictions during the large scale experiment a number of further issues need to be addressed in
further experiments to allow for a concluding evaluation of that treatment concept.

Conference presentations and posters | 2021

Advances in biomass gasification for the production of Bioheat, bioelectricity and biofuels

Anca-Couce A, Archan G, Von Berg L, Pongratz G, Martini S, Buchmayr M, Rakos C, Hochenauer C, Scharler R. Advances in biomass gasification for the production of Bioheat, bioelectricity and biofuels. 29th European Biomass Conference and Exhibition, EUBCE 2021, 26-29 April 2021. 2021.

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Current barriers to increase the use of bioenergy for different applications are first discussed. Then, recent advances are presented on gasification-based technologies to overcome these barriers that have been reached at TU Graz together with several partners. Gasification-based fuel bed concepts integrated in biomass combustion can significantly reduce emissions for bioheat production. Advances are presented for modern biomass boilers, significantly reducing nitrogen oxides and particle matter emissions as well as increasing the feedstock flexibility; and micro-gasifiers for traditional biomass utilization, significantly reducing the emissions of unburnt products. Gasification-based processes have as well the possibility to score high electrical efficiencies and to synthetize several products as second-generation biofuels. Advances are presented on measures for reducing the presence of contaminants as tars, including the catalytic use of char for tar cracking; and in applications of the producer gas, including gas cleaning and direct coupling with a solid oxide fuel cell to maximize electricity production. © 2021, ETA-Florence Renewable Energies.

Conference presentations and posters | 2011

Agricultural Biomass for Small-scale Combustion Units

Wopienka E. Agricultural Biomass for Small-scale Combustion Units, Central Europe Biomass Conference 2011, 26th-29th of January 2011, Graz, Austria.

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Other Publications | 2016

Air pollution reduction due to the adoption of high efficiency small scale pellet boilers characterized by low emissions

Chiesa M, Monteleone B, Venuta ML, Maffeis G, Greco S, Cherubini A, Schmidl C, Finco A, Gerosa G, Ballarin Denti A. Air pollution reduction due to the adoption of high efficiency small scale pellet boilers characterized by low emissions. Biomass and Bioenergy. 1 July 2016;90: 262-272.

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Conference presentations and posters | 2014

Air quality management and biomass burning at domestic level

Aigenbauer S, Bachmaier H, Figl F, Hartmann H, Haslinger W et al. Air quality management and biomass burning at domestic level, Progetto Fuoco 2014, 19th-23rd of February 2014, Verona, Italy.

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Peer reviewed papers | 2015

Air staging to reduce emissions from energy crop combustion in small scale applications

Carroll JP, Finnan JM, Biedermann F, Brunner T, Obernberger I. Air staging to reduce emissions from energy crop combustion in small scale applications. Fuel. 2015;155:37-43.

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The results of experimental work to investigate the effects of air staging on emissions from energy crop combustion in small scale applications are presented. Five different biomass fuels (wood, willow, miscanthus, tall fescue and cocksfoot) were combusted in a small scale (35 kW) biomass boiler and three different tests looking at the effects of (1) air ratio in the primary combustion chamber (primary air ratio), (2) temperature in the primary combustion chamber, and (3) overall excess air ratio, on NOx and particulate emissions were conducted. It was shown that by varying the primary air ratio, NOx emission reductions of between 15% (wood) and 30% (Miscanthus) and PM1 reductions of between 16% (cocksfoot) and 26% (wood) were possible. For all fuels, both NOx and particulate emissions were minimised at a primary air ratio of 0.8. Particulate emissions from miscanthus increased with increasing temperature in the primary combustion chamber, NOx emissions from Miscanthus and from willow also increased with temperature. Overall excess air ratio has no effect on emissions as no significant differences were found for any of the fuels. Emissions of particulates and oxides of nitrogen from a wide range of biomass feedstocks can be minimised by optimising the primary air ratio and by maintaining a temperature in the primary combustion chamber of approximately 900 °C.

Reports | 2019

Aktuelle Daten und Ausblick auf 2050

Schwarz M, Strasser C. Aktuelle Daten und Ausblick auf 2050. Factsheet Staubemissionen. October 2019.

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Other Publications | 2021

Algae4Fish - Video

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Peer reviewed papers | 2020

Alkaline Ethanol Oxidation Reaction on Carbon Supported Ternary PdNiBi Nanocatalyst using Modified Instant Reduction Synthesis Method

Cermenek B, Genorio B, Winter T, Wolf S, Connell JG, Roschger M, Letofsky-Papst I, Kienzl N, Bitschnau B, Hacker V. Alkaline Ethanol Oxidation Reaction on Carbon Supported Ternary PdNiBi Nanocatalyst using Modified Instant Reduction Synthesis Method. Electrocatalysis. 2020.11:203-204.

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Direct ethanol fuel cells (DEFC) still lack active and efficient electrocatalysts for the alkaline ethanol oxidation reaction (EOR). In this work, a new instant reduction synthesis method was developed to prepare carbon supported ternary PdNiBi nanocatalysts with improved EOR activity. Synthesized catalysts were characterized with a variety of structural and compositional analysis techniques in order to correlate their morphology and surface chemistry with electrochemical performance. The modified instant reduction synthesis results in well-dispersed, spherical Pd85Ni10Bi5 nanoparticles on Vulcan XC72R support (Pd85Ni10Bi5/C(II-III)), with sizes ranging from 3.7 ± 0.8 to 4.7 ± 0.7 nm. On the other hand, the common instant reduction synthesis method leads to significantly agglomerated nanoparticles (Pd85Ni10Bi5/C(I)). EOR activity and stability of these three different carbon supported PdNiBi anode catalysts with a nominal atomic ratio of 85:10:5 were probed via cyclic voltammetry and chronoamperometry using the rotating disk electrode method. Pd85Ni10Bi5/C(II) showed the highest electrocatalytic activity (150 mA⋅cm−2; 2678 mA⋅mg−1) with low onset potential (0.207 V) for EOR in alkaline medium, as compared to a commercial Pd/C and to the other synthesized ternary nanocatalysts Pd85Ni10Bi5/C(I) and Pd85Ni10Bi5/C(III). This new synthesis approach provides a new avenue to developing efficient, carbon supported ternary nanocatalysts for future energy conversion devices.

Other Publications | 2023

Alps4GreenC: Implementation pathways for sustainable Green Carbon production in the Alpine Region

Carlon E, Moser K, Seldmayer I, Klauser F. Alps4GreenC: Implementation pathways fpr sustainable Green Carbon production in the Alpine Region. BEST Center Day. 28 June 2023

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The Alpine Region is characterized by a high density of biomass processing and conversion plants. Alps4GreenC sets the scene for transnational utilization of biomass residues in biochar-based value chains. The project aims at:

  • Researching opportunities for conversion of biomass residues with focus on biochar production.
  • Increasing awareness of citizens, plant owners, policy makers and all involved stakeholders.
  • Establishing connection and coordination among Austria, Italy and Slovenia.
Peer reviewed papers | 2019

Ammonia as Promising Fuel for Solid Oxide Fuel Cells: Experimental Analysis and Performance Evaluation

Stöckl B, Preininger M, Subotic V, Schröttner H, Sommersacher P, Seidl M, Megel S, Hochenauer C. Ammonia as Promising Fuel for Solid Oxide Fuel Cells: Experimental Analysis and Performance Evaluation. ECS Transactions; The Electrochemical Society 2019.91:1601-1610

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n the course of this study the direct utilization of ammonia in different types of solid oxide fuel cells (SOFCs), such as anode- and electrolyte-supported SOFC, is investigated. Experiments in low fuel utilization, exhibited excellent performance of ammonia in SOFCs, although the power outputs of equivalent hydrogen/nitrogen fuels were not attained due to the incomplete endothermic ammonia decomposition. Next, the single cells were operated under high fuel utilization conditions and methane was added to the humidified ammonia stream, where they showed excellent ammonia- and methane conversions. The stability of the cells used was proven over a period of at least 48 hours with a variety of fuel mixtures. Post mortem scanning electron microscopy analysis of the anode micro-structures indicated nitriding effects of nickel, as microscopic pores and enlargements of the metallic parts occurred. Finally, a long-term test over 1,000 hours was carried out using a ten-layer stack consisting of electrolyte-supported cells.

Peer reviewed papers | 2021

An adaptive short-term forecasting method for the energy yield of flat-plate solar collector systems

Unterberger V, Lichtenegger K, Kaisermayer V, Gölles M, Horn M. An adaptive short-term forecasting method for the energy yield of flat-plate solar collector systems. Applied Energy. 2021 Apr 16;2021(293). https://doi.org/10.1016/j.apenergy.2021.116891

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The number of large-scale solar thermal installations has increased rapidly in Europe in recent years, with 70 % of these systems operating with flat-plate solar collectors. Since these systems cannot be easily switched on and off but directly depend on the solar radiation, they have to be combined with other technologies or integrated in large energy systems. In order to most efficiently integrate and operate solar systems, it is of great importance to consider their expected energy yield to better schedule heat production, storage and distribution. To do so the availability of accurate forecasting methods for the future solar energy yield are essential. Currently available forecasting methods do not meet three important practical requirements: simple implementation, automatic adaption to seasonal changes and wide applicability. For these reasons, a simple and adaptive forecasting method is presented in this paper, which allows to accurately forecast the solar heat production of flat-plate collector systems considering weather forecasts. The method is based on a modified collector efficiency model where the parameters are continuously redetermined to specifically consider the influence of the time of the day. In order to show the wide applicability the method is extensively tested with measurement data of various flat-plate collector systems covering different applications (below 200 Celsius), sizes and orientations. The results show that the method can forecast the solar yield very accurately with a Mean Absolute Range Normalized Error (MARNE) of about 5 % using real weather forecasts as inputs and outperforms common forecasting methods by being nearly twice as accurate.

Peer reviewed papers | 2024

An econometric analysis of the sawmill by-product market to explore bioeconomy options in Austria

Fuhrmann M, Dißauer C, Strasser C, Schmid E. An econometric analysis of the sawmill by-product market to explore bioeconomy options in Austria. Biomass and Bioenergy. 2024.180:107007

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Bioeconomy strategies promote higher shares of biomass products in material and energy sectors. Deploying by-products from sawmills is therefore of major interest. This study aims at analyzing market characteristics and implications of bioeconomy strategies by combining three methods: First, an econometric supply and demand model for sawmill by-products (SBP) was estimated based on data from 2001 to 2020. Second, the model was used to analyze a reference and a bioeconomy scenario. Third, a use case was analyzed dealing with the integration of wood gasification and BioSNG (Synthetic Natural Gas) production into Austrian flows of SBP. The results indicate that SBP supply reacts unit-elastic to sawnwood exports, while both supply and demand respond inelastic to SBP prices. Demand is positively inelastic related to SBP as input in panel and pellet production. In a bioeconomy scenario, long-term supply would exceed demand, resulting in additional SBP to be used for gasification. A 100 MW BioSNG plant converting these SBP could provide 528 MWh BioSNG per year. This is a 11 % share of the Austrian target value of 5 TWh green gas.

 

Conference presentations and posters | 2013

An environmental impact assessment of Romanian wood pellets delivered to Austrian households and converted into heat

Maderthaner E, Ehrig R. An environmental impact assessment of Romanian wood pellets delivered to Austrian households and converted into heat, Word Sustainable Energy Days next 2013, 27th-28th of February 2013, Wels, Austria.

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Peer reviewed papers | 2017

An experimental approach aiming the production of a gas mixture composed of hydrogen and methane from biomass as natural gas substitute in industrial applications

Kraussler M, Schindler P, Hofbauer H. An experimental approach aiming the production of a gas mixture composed of hydrogen and methane from biomass as natural gas substitute in industrial applications. Bioresource Technology. August 2017;237: 39-46.

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Conference presentations and posters | 2013

An Experimental Approach for the Production of Pure Hydrogen Based on Wood Gasification

Fail S, Diaz N, Konlechner D, Hackel M, Sanders E, Rauch R, Harasek M, Bosch K, Schwenninger F, Zapletal P, Schee Z, Hofbauer H. An Experimental Approach for the Production of Pure Hydrogen Based on Wood Gasification, International Conference on Polygeneration Strategies (ICPS13) 2013, 3th-5th of September 2013, Vienna, Austria. p 109-117. (peer reviewed)

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Other papers | 2016

An investigation on the behavior of impurities over a water gas shift stage using biomass derived syngas for hydrogen production

Loipersböck J, Lenzi M, Rauch R, Hofbauer H. An investigation on the behavior of impurities over a water gas shift stage using biomass derived syngas for hydrogen production. iSGA 2016 - 5th International Symposium on Gasification and its Applications (invited lecture). November/December 2016, Busan, Korea.

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Other papers | 2017

An investigation on the behaviour of nitrogen based impurities over a water gas shift stage and a biodiesel scrubber

Loipersböck J, Rauch R, Hofbauer H. An investigation on the behaviour of nitrogen based impurities over a water gas shift stage and a biodiesel scrubber. 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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Peer reviewed papers | 2023

Anaerobic acidification of pressed sugar beet pulp for mcl-polyhydroxyalkanoates fermentation

Kacanski M, Knoll L, Nussbaumer M, Neuriter M, Drosg B. Anaerobic acidification of pressed sugar beet pulp for mcl-polyhydroxyalkanoates fermentation. Process Biocemistry.2023:131;235-243,

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Anaerobic acidification of pressed sugar beet pulp (PSBP) is a promising strategy for the transition towards a circular economy. In this work, volatile fatty acids were produced by anaerobic acidification of PSBP and subsequently converted to mcl-polyhydroxyalkanoates. The results point to mesophilic acidification as superior to thermophilic one. At the same time, the pH regulated at the value of 6.0 showed a decisive advantage over both the pH of 7.0 and the lack of pH regulation. Furthermore, the conditions with a hydraulic retention time (HRT) of 10 days significantly outperformed those with an HRT of 6 days. The best-performing process (mesophilic, pH controlled at 6, HRT of 10 days) was successfully scaled up to a 250 L reactor, reaching a volatile fatty acid (VFA) concentration of up to 27.8 g L-1. Finally, the produced VFA were investigated as feedstock for mcl-PHA producers, Pseudomonas citronellolis and Pseudomonas putida. Both strains grew and produced PHA successfully, with P. citronellolis reaching a biomass of 15.6 g L-1 with 38% of mcl-PHA, while P. putida grew to 15.2 g L-1 with a polymer content of 31%. This study proves that acidified PSBP is a valuable feedstock for mcl-PHA production and an important approach to developing biorefineries.

Peer reviewed papers | 2019

Anaerobic Digestion of Pretreated Industrial Residues and Their Energetic Process Integration

Bochmann G, Pesta G, Rachbauer L, Gabauer W. Anaerobic Digestion of Pretreated Industrial Residues and Their Energetic Process Integration. Frontiers in Bioengineering and Biotechnology. June 2020. 8:487.

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The food and beverage industry offers a wide range of organic feedstocks for use in biogas production by means of anaerobic digestion (AD). Microorganisms convert organic compounds—solid, pasty, or liquid ones—within four steps to biogas mainly consisting of CH4 and CO2. Therefore, various conversion technologies are available with several examples worldwide to show for the successful implementation of biogas technologies on site. The food and beverage industry offer a huge potential for biogas technologies due to the sheer amount of process residues and their concurrent requirement for heat and power. The following study analyzes specific industries with respect to their implementation potential based on arising waste and heat and power demand. Due to their chemical composition, several feedstocks are resistant against microbiological degradation to a great extent. A combination of physical-, chemical-, and microbiological pretreatment are used to increase the biological availability of the feedstock. The following examples will discuss how to best implement AD technology in industrial processes. The brewery industry, dairy production, slaughterhouses, and sugar industry will serve as examples.

Peer reviewed papers | 2015

Anaerobic digestion of thermal pretreated brewers' spent grains

Bochmann G, Drosg B, Fuchs W. Anaerobic digestion of thermal pretreated brewers' spent grains. Environmental Progress and Sustainable Energy. 2015;34(4):1092-6.

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Anaerobic digestion offers a good opportunity to degrade residues from breweries to biogas. To improve the anaerobic degradation process thermal pretreatment of brewers' spent grains (BSG) offers the opportunity to increase degradation rate and biogas yield. Aim of the work is to show the influence of the thermal pretreatment of BSG to anaerobic digestion. BSG were pretreated at different temperature levels from 100 to 200°C. The biogas production of thermally pretreated BSG lies between 30 and 40% higher than for untreated reference. The temperature of the pretreatment process has a significant influence on the degradation rate or gas yield, respectively. Up to a temperature of 160°C, the biogas yield rises. Temperatures over 160°C result in a slower degradation and decreasing biogas yield. Substrate with and without pretreatment gave a daily biogas yield of 430 and 389 Nm3 × kg-1 VS, respectively. Batch analysis of the biochemical methane potential gives a total methane yield of 409.8 Nm3 CH4 × kg-1 VS of untreated brewers' spent grains and 467.6 Nm3 CH4 × kg-1 VS of the pretreated samples. For pretreatment energy balance estimation has been carried out. Without any heat recovery demand is higher than the energy surplus resulting from pretreatment of BSG. With energy recovery by heat exchanger the net energy yield could be increased to 38.87 kWh × kg-1 FM or 8.81%. © 2015 American Institute of Chemical Engineers Environ Prog.

Conference presentations and posters | 2020

Anaerobic Digestion Optimization for Biogas and Biomethane Production

Ionel I, Drosg B. Anaerobic Digestion Optimization for Biogas and Biomethane Production. 28th European Biomass Conference and Exhibition (oral presentation) 2020.

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Other Publications | 2016

Analisi del ciclo di vita di caldaie a pellet di bassa potenza caratterizzate da alta efficienza e ridotte emissioni

Monteleone B, Chiesa M, Marzuoli R, Verma VK, Schwarz M, Carlon E, Schmidl C, Ballarin Denti A. Analisi del ciclo di vita di caldaie a pellet di bassa potenza caratterizzate da alta efficienza e ridotte emissioni. Agriforenergy. February 2016.

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Other Publications | 2012

Analyse ausgewählter europäischer Biomassemärkte

Hollinger, K. Analyse ausgewählter europäischer Biomassemärkte, Diploma Thesis, FH-Burgenland, Pinkafeld, Austria, 2012.

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Other Publications | 2013

Analyse und Optimierung der Verfügbarkeit vom BHKW Güssing

Tripolt, M. Analyse und Optimierung der Verfügbarkeit vom BHKW Güssing, Master Thesis, Technische Universität Wien, Vienna, Austria, 2013.

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Peer reviewed papers | 2021

Analysing price cointegration of sawmill by-products in the forest-based sector in Austria

Fuhrmann M, Dißauer C, Strasser C, Schmid E. Analysing price cointegration of sawmill by-products in the forest-based sector in Austria. Forest Policy and Economics. 2021.131:102560.

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Empirical analyses of interlinkages and price dependencies in the forest-based sector support the forecast of market developments and the design of efficient utilization pathways. This article aims at analysing price cointegration between roundwood (sawlogs, pulpwood), sawmill by-products (sawdust, wood chips) and wood products (pellets, particle board) in the forest-based sector in Austria. Monthly price data for the period 2005–2019 were used for the following statistical tests: (1) The Augmented-Dickey-Fuller and Zivot-Andrews unit root tests were conducted to investigate stationarity of the data; (2) The Johansen Cointegration test was pairwise applied to price time series; (3) The Granger Causality test was used for cointegrated time series to examine which one is price leading. Furthermore, sawmill by-product prices were modelled as Vector Error Correction Models (VECM) to analyse their common behaviour. The dataset was divided to a training (2005–2017) and test (2018–2019) subset to assess the prediction accuracy of the models. The training data were used to estimate a VAR model as basis for forecasts, which were compared to the test data. Results show that sawdust prices are cointegrated and thus modelled with pellet and particle board prices. In contrast, wood chips are used for several applications and thus prices are cointegrated and modelled with prices of sawlogs, pulpwood, pellets and particle board. The comparison with the test data showed that forecasts were able to predict data from 2018 to 2019 well. However, a decrease in prices, starting in 2019 and intensified by the Covid-19 pandemic, could not be fully captured by these forecasts.

Other Publications | 2014

Analysis of Environmental and Economic Aspects of International Pellet Supply Chains

Ehrig, R. Analysis of Environmental and Economic Aspects of International Pellet Supply Chains, Ph.D. Thesis, Vienna University of Technology, Vienna, Austria, 2014.

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Biomass plays a key role to achieve the EU's 20-20-20 energy and climate targets. Because of rising European demand and limited domestic resources, the EU relies on worldwide imports. Given this framework, the present thesis explores the inuences on wood pellet supply chains considering dierent environmental policies, price risks and the eect of torrefaction pretreatment. The examinations refer to three real case studies for pellet trade from Australia, Canada, and Russia to Europe. In the rst investigation, the eciency of co-ring imported wood pellets in terms of CO2 savings and related subsidy schemes is analysed. Scenarios show that co-ring biomass is ecient to contribute to the EU energy targets. Though, policy makers could use these instruments more eective when directing sourcing decision towards options with even less environmental impacts. The second analysis explores the inuence of statistically derived price risks on total supply chain economics. It is shown that price risks can eect strong uctuations in the short term, which seriously aect the protability of individual trade routes. Securing the supply chain is mainly based on individual producer-buyer agreements, personal branch experiences and fast reactions on the subsidy system. Systematic evaluation of supply chains could contribute to a more reliable market and thus foster investment decisions. In the last investigation, the economic and environmental performance of potential torrefaction-based supply chains is assessed. As a result, torrefaction-based supply
chains turn out to be a certain alternative to conventional ones. Though, still huge research eorts and industrial demonstration are required to make torreed biomass a real alternative on the market.

 

Peer reviewed papers | 2021

Analysis of H2S-related short-term degradation and regeneration of anode- and electrolyte supported solid oxide fuel cells fueled with biomass steam gasifier product gas

Pongratz G, Subotić V, Schroettner H, Hochenauer C, Skrzypkiewicz M, Kupecki J, Anca-Couce A, Scharler R. Analysis of H2S-related short-term degradation and regeneration of anode- and electrolyte supported solid oxide fuel cells fueled with biomass steam gasifier product gas. Energy.2021.218:119556.

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Using solid oxide fuel cells in biomass gasification based combined heat and power production is a promising option to increase electrical efficiency of the system. For an economically viable design of gas cleaning units, fuel cell modules and further development of suitable degradation detection methods, information about the behavior of commercially available cell designs during short-term poisoning with H2S can be crucial. This work presents short-term degradation and regeneration analyses of industrial-relevant cell designs with different anode structure and sulfur tolerance fueled with synthetic product gas from wood steam gasification containing 1 to 10 ppmv of H2S at 750°C and 800°C. Full performance regeneration of both cell types was achieved in all operating points. The high H2O content and avoided fuel depletion may have contributed to a lower performance degradation and better regeneration of the cells. A strong influence of the catalytically active anode volume on poisoning and regeneration behavior was quantified, thereby outlining the importance of considering the anode structure besides the sulfur tolerance of the anode material. Hence, cells with less sulfur tolerant anode material but larger anode volume might outperform cells less sensitive to sulfur in the case of an early detection of a gas cleaning malfunction.

Peer reviewed papers | 2016

Analysis of optimization potential in commercial biomass gasification plants using process simulation

Wilk V, Hofbauer H. Analysis of optimization potential in commercial biomass gasification plants using process simulation. Fuel Processing Technology. 01 December 2016;141: 138-147.

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Other papers | 2014

Analysis of woody biomass commodity price volatility in Austria

Kristöfel C, Strasser C, Morawetz UB, Schmidt J, Schmid E. Analysis of woody biomass commodity price volatility in Austria. Biomass Bioenergy. 2014;65:112-124.

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Several energy and agricultural commodities have experienced higher price volatility in recent years. Management of price risks usually leads to additional costs that are often shared and transmitted along the supply chain to the final consumers. Only little information is currently available on how price volatility of woody biomass commodities has developed compared to energy and agricultural commodities in recent years. We compute the historic price volatility of woody biomass commodities using the standard deviation of log returns as well as univariate GARCH models. The results show that the price volatility of several woody biomass commodities has increased in recent years. However, the price volatility of woody biomass is still lower compared to the price volatility of agricultural commodities and fossil fuels. The analysis of factors and linkages provides insights of the current biomass market developments.

Other Publications | 2012

Analytical approach for the determination of micro elements in anaerobic digestion systems by sequential extraction technique

Rachbauer, L. Analytical approach for the determination of micro elements in anaerobic digestion systems by sequential extraction technique, Master Thesis, University of Natural Resources and Life Sciences Vienna, Vienna, Austria, 2012.

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Der Einfluss von Nährstoffzusammensetzung und Additivzugabe beim anaeroben Abbau organischer Substanz stieß in den letzten Jahren vermehrt auf Interesse. Im Besonderen Spurenelemente haben erwiesenermaßen erheblichen Einfluss auf u.a. methanogene Archaeen und deren metabolische Aktivität. Massive Probleme der Prozessstabilität speziell bei Monovergärung unterschiedlichster Substrate können durch Co-Fermentation oder gezielte Zudosierung von Spurenelementmischungen überwunden werden. Ein profundes Verständnis der Wirkung dieser Elemente auf die verschiedenen mikrobiellen Spezies im Biogasreaktor als auch ihre Verfügbarkeit, ist die Voraussetzung für eine wirtschaftliche Gestaltung des anaeroben Fermentationsprozesses organischer Roh- als auch Reststoffe. Der heutige Stand-der-Technik zur Analyse von Biogasproben hat seinen Ursprung in der Wasser-, Abwasser- und Schlammanalytik und besteht aus einem einzelnen Filtrationsschritt vor Elementdetektion mittels ICP-OES bzw. ICP-MS. Diese Methodik erlaubt nur einen äußerst begrenzten Einblick in die Verteilung von essentiellen Spurenelementen in Anaerobreaktoren. Eine aussagekräftige Beurteilung der mikrobiellen Verfügbarkeit von beispielsweise Cobalt, Nickel oder Molybdän ist somit nur eingeschränkt möglich. Ziel dieser Arbeit war es, eine bestehende Methode zur sequentiellen Extraktion aus dem Bereich der Boden- und Sedimentanalytik für die Anwendung auf Biogasproben zu adaptieren. Der daraus resultierende Einblick in die Verteilung von Spurenelementen in den einzelnen Fraktionen erlaubt eine genauere Bewertung der mikrobiellen Verfügbarkeit von Nährstoffen in Biogasreaktoren, verglichen mit bestehenden analytischen Untersuchungsmethoden. Anforderungen an das Verfahren wie die Reproduzierbarkeit der Daten, zeitsparende Analytik und wirtschaftliche Realisierbarkeit konnten erfüllt werden. Wiederfindungsraten zwischen 90 und 110 % wurden für die wichtigsten Spurenelemente erreicht. Durch die sequentielle Extraktion konnte gezeigt werden, dass essenzielle Mikro-Nährstoffe bis zu 98 % in einer unlöslichen Form vorliegen können. Die Ergebnisse dieser Arbeit belegen die Anwendbarkeit der entwickelten Methodik zur Spurenelement-Extraktion in Anaerob-Systemen.

Conference presentations and posters | 2010

Annual efficiency determination of pellets boilers: Method, applications and new possibilities for the differentiation of the quality of pellets boilers

Haslinger W, Heckmann M, Schmidl C, Schwarz M. Annual efficiency determination of pellets boilers: Method, applications and new possibilities for the differentiation of the quality of pellets boilers, 10. Industrieforum Pellets, 7th-8th of September 2010, Stuttgart, Germany.

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Conference presentations and posters | 2012

Annual efficiency of small scale biomass combustion systems

Haslinger W, Schmidl C, Schwarz M, Verma VK, Hebenstreit B, Carlon E, Golicza L, Hartmann H, Brandt J, Weissinger A, Berger H, Wörgetter M. Annual efficiency of small scale biomass combustion systems, IEA Bioenergy Conference 2012, 13th-15th of November 2012, Vienna, Austria.

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Peer reviewed papers | 2016

Apparent kinetics of the catalyzed water-gas shift reaction in synthetic wood gas

Plaza A, Fail S, Cortés JA, Föttinger K, Diaz N, Rauch R, Hofbauer H. Apparent kinetics of the catalyzed water-gas shift reaction in synthetic wood gas. Chemical Engineering Journal. 1 October 2016;301: 222-228.

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Peer reviewed papers | 2017

Apparent kinetics of the water-gas-shift reaction in biomass gasification using ash-layered olivine as catalyst.

Krycaa J, Priščák J, Łojewskac J, Kuba M, Hofbauer H. Apparent kinetics of the water-gas-shift reaction in biomass gasification using ash-layered olivine as catalyst. Chemical Engineering Journal. 2018, 346: 113-119.

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Substitution of fossil fuels for production of electricity, heat, fuels for transportation and chemicals can be realized using biomass steam gasification in a dual fluidized bed (DFB).

Interaction between biomass ash and bed material in a fluidized bed leads to transformation of the bed particle due to enrichment of components from the biomass ash resulting in the development of ash layers on the bed particle surface. These ash-rich particle layers enhance the catalytic activity of the bed material regarding the water-gas-shift reaction and the reduction of tars.

The water-gas-shift reaction at conditions typical for dual fluidized bed biomass gasification at a temperature of 870 °C was investigated. Diffusion and heat transfer limitations were minimized using a lab-scale experimental set-up consisting of a gas mixing section and a quartz glass reactor in which the catalyst is investigated.

 

 

 

Conference presentations and posters | 2013

Applicability and slag formation survey of different biomass fuel qualities in small scale combustion – a Substudy in the EU FP7-SME project AshMelT

Schwabl M, Feldmeier S, Nagelhofer K, Wopienka E, Haslinger W. Applicability and slag formation survey of different biomass fuel qualities in small scale combustion – a Substudy in the EU FP7-SME project AshMelT, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 1156-1159.

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Peer reviewed papers | 2019

Applicability of Fuel Indexes for Small-Scale Biomass Combustion echnologies, Part 2: TSP and NOx Emissions

Feldmeier S, Wopienka E, Schwarz M, Schön C, Pfeifer C. Applicability of Fuel Indexes for Small-Scale Biomass Combustion echnologies, Part 2: TSP and NOx Emissions. Energy & Fuels. 2019.33:11724-11730.

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Several studies pointed out that emission release is related to the concentration of particular elements in the fuel. Fuel indexes were developed to predict emissions of biomass combustion based on the elemental composition of the fuel. This study focuses on emissions of different biomass combustion technologies for domestic heating. Based on combustion tests with a wide range of fuel qualities we validated fuel indexes from the literature. We calculated the values for predicting total suspended particulate (TSP) matter and nitrogen oxide (NOx) emission of 39 biomass-derived fuels. Combustion tests conducted in 10 different small-scale appliances provided experimental data. The combustion technologies had a nominal load between 6 and 140 kWth. We measured TSP and NOx emissions during the stable phases of the experiments. The evaluation considered 529 combustion test intervals. All tested indexes for predicting the TSP corresponded well to the measured values. The correlation analysis confirmed that these indexes are associated with each other and are basically dominated by the concentration of potassium. The results regarding NOx emissions confirm previous findings from the literature by showing the typical nonlinear relation between nitrogen content of the fuel and NOx in the flue gas. Overall the comparison of the fuel indexes with the practical data indicated also an influence of the combustion technologies.

Peer reviewed papers | 2019

Applicability of Fuel Indexes for Small-Scale Biomass Combustion Technologies, Part 1: Slag Formation

Feldmeier S, Wopienka E, Schwarz M, Schön C, Pfeifer C. Applicability of Fuel Indexes for Small-Scale Biomass Combustion Technologies, Part 1: Slag Formation. Energy & Fuels. November 2019. 33:10969-10977.

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Several methods are available to predict the combustion behavior of fuels. Fuel indexes have been developed either for specific fuel types (e.g., coal, biomass) or their utilization in combustion technology (fluidized bed, grate systems). This study deals with the validation of fuel indexes for biomass fuels utilized in small-scale appliances for residential heating. Laboratory analysis data of 33 biomass-derived fuels were used for determining indexes for predicting slag formation tendencies. Indexes were selected that have been reported and previously applied in the literature. They vary in terms of their derivation: ratio or concentration of specific components that are relevant for ash chemistry, temperature-based indexes, and empirical correlations. Combustion tests with 9 different small-scale appliances were conducted to gain experimental data. The appliances had a nominal load between 6 kWth and 140 kWth. After each experiment, the fraction of fuel ash that formed slag was quantified. Because of several boiler–fuel combinations in total, data from 90 combustion experiments were available for evaluation. The comparison of the quantified slag with the calculated slagging indexes showed that the applicability was strongly dependent on the (chemical) background of the respective index. Also, the fuel composition (e.g., fuels rich in calcium, silicon or phosphorus) plays an important role. Thus, available indexes are not applicable without restrictions and require a closer look on fuel properties and possible ash transformation mechanisms. Overall, the comparison of the fuel indexes with practical data (slag formation) also indicated an influence of the combustion technologies and operation conditions. The comparison of indexes that predict particulate matter and nitrogen oxide emissions with data measured during combustion experiments was evaluated as well. These results will be described in the second part of the present work.

Peer reviewed papers | 2019

Applicability of the SOFC technology for coupling with biomass-gasifier systems: Short- and long-term experimental study on SOFC performance and degradation behaviour

Subotić V, Baldinelli A, Barelli L, Scharler R, Pongratz G, Hochenauer C, Anca-Couce A. Applicability of the SOFC technology for coupling with biomass-gasifier systems: Short- and long-term experimental study on SOFC performance and degradation behaviour. Applied Energy. 2019.256:113904

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Coupling biomass gasification with high temperature Solid Oxide Fuel Cells (SOFCs) is a promising solution to increase the share of renewables and reduce emissions. The quality of the producer gas used can, however, significantly impact the SOFC durability and reliability. The great challenge is to ensure undisturbed operation of such system and to find a trade-off between optimal SOFC operating temperature and system thermal integration, which may limit the overall efficiency. Thus, this study focuses on experimental investigation of commercial SOFC single cells of industrial size fueled with different representative producer gas compositions of industrial relevance at two relevant operating temperatures. The extensive experimental and numerical analyses performed showed that feeding SOFC with a producer gas from a downdraft gasifier, with hot gas cleaning, at an operating temperature of 750 °C represents the most favorable setting, considering system integration and the highest fuel utilization. Additionally, a 120 h long-term test was carried out, showing that a long-term operation is possible under stated operating conditions. Local degradation took place, which can be detected at an early stage using appropriate online-monitoring tools.

Peer reviewed papers | 2020

Applicability of Torrefied Sunflower Husk Pellets in Small and Medium Scale Furnaces

Kienzl N, Margaritis N, Isemin R, Zaychenko V, Strasser C, Kourkoumpas DS, Grammelis P, Klimov D, Larina O, Sytchev G, Mikhalev A. Applicability of Torrefied Sunflower Husk Pellets in Small and Medium Scale. Waste and Biomass Valorization. 2020;275:122882.

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The aim of this paper is to test the applicability of upgraded agricultural biomass feedstock such as torrefied sunflower husks during combustion in small and medium heating applications. Sunflower husk is formed in large quantities at enterprises producing sunflower oil and can be used as biofuel. However, big problems arise due to the low bulk density of husks and the rapid growth of ash deposits on the heating surfaces of boilers. In order to solve these problems, it was proposed to produce pellets from husks, and to subject these pellets to torrefaction. After torrefaction, net calorific value was increased by 29% while the risk of high temperature corrosion of boilers was reduced. Signs of ash softening neither occurred in combustion of raw nor in combustion of torrefied sunflower husk pellets. High aerosol emissions, already present in raw sunflower husk pellets, could not be mitigated by torrefaction. First combustion results at medium scale furnaces indicated that sunflower husk pellets (both raw and torrefied) in a commercial boiler < 400 kW, operated in a mode with low primary zone temperatures (< 850 °C), meet current emission limits. Regarding the future upcoming emission limits according to the European Medium Combustion Plant Directive, additional measures are required in order to comply with the dust limits.

Conference presentations and posters | 2014

Applicability survey of different torrefied biomass fuels in small scale appliances

Feldmeier S, Schwabl M, Wopienka E, Strasser C, Haslinger W. Applicability survey of different torrefied biomass fuels in small scale appliances, 22nd European Biomass Conference 2014, 23rd-26th of June 2014, Hamburg, Germany. p 662-666.

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The torrefaction process is a promising key technology for biomass treatment. An improvement of the fuel properties, e.g. a higher gross calorific value and a resulting increased energy density, is expected. The changed fuel properties in terms of water repellence enable an improved storability. However, the modified fuel characteristics change the combustion behaviour of the fuel. Since small­scale pellet boilers mainly are dedicated to wood pellets, the applicability of torrefied fuel yet remains unclear. Within the EU FP7 project SECTOR, amongst others, the end­use application of torrefied biomass was investigated in several small scale appliances and the behaviour during the stationary operational conditions of the combustion process was assessed. The experimental design was divided in two parts: First, a survey of the combustion appliances was conducted in order to observe the influence of the changed fuel properties on the different boiler systems. Afterwards, the combustion behaviour of torrefied pellets made of different raw material quality was monitored by utilizing the test fuels and monitor the emission release. The results of these experimental series provide an initial indication for the feasibility of the utilization of several torrefied fuels in state­of­the­art pellet boilers.

Conference presentations and posters | 2008

Application Fields of Sensor-based Sorting in Waste Management - Limits and Research Demand

Faist V, Ragossnig A. Application Fields of Sensor-based Sorting in Waste Management - Limits and Research Demand, ISWA Annual Congress 2008, 3rd-6th of November, Singapur.

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Conference presentations and posters | 2014

Application of a Model Based Control Strategy at a Fixed Bed Biomass District Heating Plant

Zemann C, Heinreichsberger O, Gölles M, Brunner T, Dourdoumas N, Obernberger I. Application of a Model Based Control Strategy at a Fixed Bed Biomass District Heating Plant. 22nd European Biomass Conference and Exhibition Proceedings. 2014;1698-1705.

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Peer reviewed papers | 2015

Application of an empirical model in CFD simulations to predict the local high temperature corrosion potential in biomass fired boilers.

Gruber T, Scharler R, Obernberger I. Application of an empirical model in CFD simulations to predict the local high temperature corrosion potential in biomass fired boilers. Biomass and Bioenergy. Volume 79, August 2015, Pages 145-154.

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To gain reliable data for the development of an empirical model for the prediction of the local high temperature corrosion potential in biomass fired boilers, online corrosion probe measurements have been carried out. The measurements have been performed in a specially designed fixed bed/drop tube reactor in order to simulate a superheater boiler tube under well-controlled conditions. The investigated boiler steel 13CrMo4-5 is commonly used as steel for superheater tube bundles in biomass fired boilers. Within the test runs the flue gas temperature at the corrosion probe has been varied between 625 °C and 880 °C, while the steel temperature has been varied between 450 °C and 550 °C to simulate typical current and future live steam temperatures of biomass fired steam boilers. To investigate the dependence on the flue gas velocity, variations from 2 m·s−1 to 8 m·s−1 have been considered. The empirical model developed fits the measured data sufficiently well. Therefore, the model has been applied within a Computational Fluid Dynamics (CFD) simulation of flue gas flow and heat transfer to estimate the local corrosion potential of a wood chips fired 38 MW steam boiler. Additionally to the actual state analysis two further simulations have been carried out to investigate the influence of enhanced steam temperatures and a change of the flow direction of the final superheater tube bundle from parallel to counter-flow on the local corrosion potential.

Other papers | 2013

Application of novel and advanced fuel characterization tools for the combustion related characterization of different wood/Kaolin and straw/Kaolin mixtures

Sommersacher P, Brunner T, Obernberger I, Kienzl N, Kanzian W. Application of novel and advanced fuel characterization tools for the combustion related characterization of different wood/kaolin and straw/kaolin mixtures. Energy and Fuels. 2013;27(9):5192-206.

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The increased demand for energy from biomass enforces the utilization of new biomass fuels (e.g., energy crops, short-rotation coppices, as well as wastes and residues from agriculture and the food industry). Compared to conventional wood fuels, these new biomass fuels usually show considerably higher ash contents and lower ash sintering temperatures, which leads to increased problems concerning slagging, ash deposit formation, and particulate matter emissions. One possibility to combat these problematic behaviors is the application of fuel additives such as kaolin. In contrast to the usual approach for the application of additives based on an experimental determination of an appropriate additive ratio, this study applies novel and advanced fuel characterization tools for the characterization of biomass/kaolin mixtures. In the first step the pure biomass fuels (softwood from spruce and straw) and the additive were chemically analyzed. On the basis of the analysis theoretical mixing calculations of promising kaolin ratios were conducted. These theoretical mixtures were evaluated with fuel indexes and thermodynamic equilibrium calculations (TEC). Fuel indexes provide the first information regarding high temperature corrosion (2S/Cl) and ash melting tendency (Si + P + K)/(Ca + Mg + Al). TEC can be used for a qualitative prediction of the release of volatile and semivolatile elements (K, Na, S, Cl, Zn, Pb) and the ash melting behavior. Moreover, selected mixtures of spruce and straw with kaolin were prepared for an evaluation and validation of the release behavior of volatile and semivolatile ash forming elements with lab-scale reactor experiments. The validation of the ash melting behavior was conducted by applying the standard ash melting test. It could be shown that the new approach to apply novel and advanced fuel characterization tools to determine the optimum kaolin ratio for a certain biomass fuel works well and thus opens a new and targeted method for additive evaluation and application. In addition, it helps to significantly reduce time-consuming and expensive testing campaigns. © 2013 American Chemical Society.

Conference presentations and posters | 2015

Application of numerical modelling to biomass grate furnaces

Mehrabian R, Shiehnejadhesar A., Scharler R. Application of numerical modelling to biomass grate furnaces. Internation conference on advances in mechanical engineering, Istanbul 2015.

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The direct combustion of the biomass is the most advanced and mature technology in the field of energetic biomass utilisation. The legislations on the amount of emitted pollutants and the plant efficiency of biomass combustion systems are continually being restricted. Therefore constant improvement of the plant efficiency and emission reduction is required Numerical modelling is gaining increasing importance for the development of biomass combustion technologies. In this paper an overview about the numerical modelling efforts deal with the most relevant phenomena in biomass grate firing systems is given. The numerical modelling results in a deeper understanding of the underlying processes in biomass combustion plants. Therefore, it leads to a faster and safer procedure of development of a new technology.

Other papers | 2022

Application of Optimization-based Energy Management Systems for Interconnected District Heating Networks

Kaisermayer V, Muschick D, Gölles M, Rosegger W, Binder J, Kelz J. Application of Optimization-based Energy Management Systems for Interconnected District Heating Networks. 22. Styrian Workshop on Automatic Control. 6 Sep. 2022. Leitring/Wagna, Österreich.

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Conference presentations and posters | 2019

Aqueous phase reforming of Fischer-Tropsch water fraction

Zoppi G, Pipitone G, Gruber H, Weber G, Reichhold A, Pirone R, Bensaid S. Aqueous phase reforming of Fischer-Tropsch water fraction. ICPS 2019.

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