Publications

Peer reviewed papers | 2020

Detailed experimental investigation of the spatially distributed gas release and bed temperatures in fixed-bed biomass combustion with low oxygen concentration

Archan G, Anca-Couce A, Gregorc J, Buchmayr M, Hochenauer C, Gruber J, Scharler R. Detailed experimental investigation of the spatially distributed gas release and bed temperatures in fixed-bed biomass combustion with low oxygen concentration. Biomass and Bioenergy. 2020;141:105725

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This publication focuses on the experimental investigation of a novel small-scale fuel flexible biomass combustion technology with a fixed-bed employing a low oxygen concentration. It was obtained through a low primary air ratio and the additional supply of recirculated flue gas. The plant was operated with spruce wood chips, which contained three different mass fractions of water, and miscanthus pellets. All relevant components of the released gas above the fixed-bed were measured, as well as the 3D bed temperature distribution. The balances confirmed a high experimental data consistency. Therefore, it was possible to determine the location of the four different conversion zones inside the fixed-bed: drying, pyrolysis, char gasification and char oxidation. The reduction of CO2 to CO in the char reduction zone worked efficiently across the entire grate area. Furthermore, the results showed that the water mass fraction of the fuel did not influence the dry product gas composition, but significantly affected the location for the release of pyrolysis products such as tars. It was found that the low oxygen concentration in the fixed-bed combined with flue gas recirculation was an effective method to reduce bed temperatures and therefore its inorganic emissions while significantly increasing feedstock flexibility. The investigations provided fundamental findings on the conversion and release behavior of the new technology under real operating conditions and are very useful for further experimental work and CFD simulations targeting the reduction of PM and NOX emissions.

Conference presentations and posters | 2020

Detailed investigations of high terpene concetrations in biogas laboratory trials

Knoll L, Sumethberger-Hasinger M, Nussbaumer M, Dalnodar D, Loibner A, Drosg B. Detailed investigations of high terpene concetrations in biogas laboratory trials. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

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Peer reviewed papers | 2021

Detailed NOX precursor measurements within the reduction zone of a novel small-scale fuel flexible biomass combustion technology

Archan G, Scharler R, Pölzer L, Buchmayr M, Sommersacher P, Hochenauer C, Gruber J, Anca-Couce A. Detailed NOX precursor measurements within the reduction zone of a novel small-scale fuel flexible biomass combustion technology. Fuel. 15 October 2021.302:121073

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A novel biomass combustion technology with a compact fixed-bed operated with a low oxygen content and double air staging was investigated. Minimized flue gas emissions at high fuel flexibility were achieved only with primary measures. The fuel nitrogen conversion mechanisms were investigated in detail in the secondary zone of a 30 kW lab-reactor, designed as efficient reduction zone. Experimental investigations were carried out to determine the distribution of gas temperatures, main dry product gas components as well as NOX precursors such as NH3 and HCN along the height of the reduction zone. The objective was to determine and understand the various fuel nitrogen conversion mechanisms in the reduction zone that can minimize NOX emissions.

It was found that the HCN/NH3 ratio increases with the fuel nitrogen content. This corresponds to an unexpected opposite trend to typical biomass grate furnaces. It was concluded that it is crucial for the HCN/NH3 ratio whether the released nitrogen tars are already cracked in the fixed-bed or only in the gas phase, as in the novel technology. Furthermore, the influence of gas temperature, air ratio, mixing, recirculated flue gas and residence time on the formation and reduction of NH3, HCN and NO is discussed.

Finally, this novel technology achieves NOX emissions of<95 mg·m−3 and 175 mg·m−3 for woody and herbaceous fuels, respectively, which is well below the small-scale state-of-the-art for the respective N contents and it achieves fuel nitrogen conversions to NOX in flue gas of 35% and 25%, respectively.

Conference presentations and posters | 2016

Detailed Reaction Schemes and Product Characterization Applied to Pyrolysis of a Single Spruce Particle

Andrés Anca-Couce, Peter Sommersacher, Robert Scharler, Christoph Hochenauer. Detailed Reaction Schemes and Product Characterization Applied to Pyrolysis of a Single Spruce Particle. 24rd European Biomass Conference & Exhibition (oral presentation).

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Conference presentations and posters | 2011

Determination of annual efficiency and emission factors of small-scale biomass boiler

Schwarz M, Heckmann M, Lasselsberger L, Haslinger W. Determination of annual efficiency and emission factors of small-scale biomass boiler, Central Europe Biomass Conference 2011, 26th-29th of January 2011, Graz, Austria.

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In the last decades certification tests of small-scale biomass systems have impressively shown the improvement of the state of the art. Though, steady state measurements represent results only foroptimal operation. In practice results differ due to varying operating conditions. Therefore, of a test stand measurement method to derive realistic annual system efficiencies and emission factors is developed. The method includes a heat loss model for thermal storages too. It can be used to test automatically fed biomass boiler, manually loaded biomass boilers and boiler / heat accumulator combinations. For the evaluation of the measurement data a calculation method based on mass flows was developed. The results of our experiments show that the newly developed method is a good tool to evaluate small-scale biomass boilers. With this method an easy and reliable instrument to determine annual system efficiencies and emission factors for realistic boiler operation is provided. The application of the method will prove that modern small-scale biomass combustion systems have the potential to significantly contribute to the reduction of air pollutants and to increase overall energy system efficiency.

Peer reviewed papers | 2018

Determination of off-gassing and self-heating potential of wood pellets - Method comparison and correlation analysis

Sedlmayer I, Arshadi M, Haslinger W, Hofbauer H, Larsson I, Lönnermark A, Pollex A, Schmidl C, Stelte W, Wopienka E, Bauer-Emhofer W. Determination of off-gassing and self-heating potential of wood pellets - Method comparison and correlation analysis. Fuel 2018;234:894-903.

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Several methods for identifying the phenomena of self-heating and off-gassing during production, transportation and storage of wood pellets have been developed in recent years. Research focused on the exploration of the underlying mechanisms, influencing factors or the quantification of self-heating or off-gassing tendencies. The present study aims at identifying a clear correlation between self-heating and off-gassing. Thus, different methods for determining self-heating and off-gassing potentials of wood pellets are compared. Therefore, eleven wood pellet batches from the European market were analyzed. For this investigation, three methods for the determination of self-heating, like isothermal calorimetry, oxi-press and thermogravimetric analysis, and four methods for off-gassing, like volatile organic compound (VOC) emissions measurements, gas phase analysis of stored pellets in a closed container by offline and by glass flask method and determination of fatty and resin acids content, were performed. Results were ranked according to the self-heating and off-gassing tendency providing a common overview of the analyzed pellets batches. Relations between different methods were investigated by Spearman’s correlation coefficient. Evaluation of the results revealed an equal suitability of offline and glass flask methods to predict off-gassing tendency and indicated a very significant correlation with isothermal calorimetry for the identification of self-heating tendency. The thermogravimetric analysis as well as the fatty and resin acids determination proved to be insufficient for the exclusive assessment of self-heating and off-gassing tendency, respectively.

Conference presentations and posters | 2014

Developing a simulation model for a mixed alcohol synthesis reactor and validation of experimental data in IPSEpro

Weber G, Di Giuliano A, Rauch R, Hofbauer H. Developing a simulation model for a mixed alcohol synthesis reactor and validation of experimental data in IPSEpro, 4th International Symposium on Gasification and its Applications (iSGA-4) 2014, 2nd-5th of September 2014, Vienna, Austria.

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The production of higher alcohols over a sulfidized molybdenum catalyst (MoS2) using a biomass-derived synthesis gas has been studied at Güssing for several years. The mixed alcohol (MA) pilot plant uses synthesis gas provided by the biomass-based combined heat and power plant (CHP) Güssing. Parameter variations were carried out wherein temperature, space velocity and gas composition were varied to evaluate the impact on CO conversion, product distribution and yield. The influence of side reactions to hydrocarbons was also a research objective. A sufficient amount of experimental data was obtained during these experiments. Evidence for the influence of various reaction parameters was found, but the mass balance could not be closed. A mathematical model of the MA synthesis reactor was developed using the stationary equation-orientated flow sheet simulation software IPSEpro. This publication gives an overview of modeling the MA reactor and condenser unit and testing the model with example calculations. Validated experimental results from 2012 parameter variation are shown and a comparison between experimental and validated quantities is carried out. A comparison with literature data shows that the observed tendencies are in good correlation to literature. The developed reactor model was enabling the possibility for carrying out a validation of the experimental data. IPSEpro uses the method of least-squares to obtain the approximate solution of the overall determined system. The established model was very close to the actual MA pilot plant. The model is very accurate about MA liquid product compositions and all measured flows.

Peer reviewed papers | 2015

Developing a simulation model for a mixed alcohol synthesis reactor and validation of experimental data in IPSEpro

Weber G, Di Giuliano A, Rauch R, Hofbauer H. Developing a simulation model for a mixed alcohol synthesis reactor and validation of experimental data in IPSEpro. Fuel Process Technology. 141:167-176, 2015.

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Peer reviewed papers | 2020

Developing an adsorption-based gas cleaning system for a dual fluidized bed gasification process

Loipersböck J, Weber G, Rauch R, Hofbauer H. Developing an adsorption-based gas cleaning system for a dual fluidized bed gasification process.Biomass Conversion and Biorefinery. 2020.

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Biomass has the potential to make a major contribution to a renewable future economy. If biomass is gasified, a wide variety of products (e.g., bulk chemicals, hydrogen, methane, alcohols, diesel) can be produced. In each of these processes, gas cleaning is crucial. Impurities in the gas can cause catalyst poisoning, pipe plugging, unstable or poisoned end products, or harm the environment. Aromatic compounds (e.g., benzene, naphthalene, pyrene), in particular, have a huge impact on stable operation of syngas processes. The removal of these compounds can be accomplished by wet, dry, or hot gas cleaning methods. Wet gas cleaning methods tend to produce huge amounts of wastewater, which needs to be treated separately. Hot gas cleaning methods provide a clean gas but are often cost intensive due to the high operating temperatures and catalysts used in the system. Another approach is dry or semi-dry gas cleaning methods, including absorption and adsorption on solid matter. In this work, special focus was laid on adsorption-based gas cleaning for syngas applications. Adsorption and desorption test runs were carried out under laboratory conditions using a model gas with aromatic impurities. Adsorption isotherms, as well as dynamics, were measured with a multi-compound model gas. Based on these results, a temperature swing adsorption process was designed and tested under laboratory conditions, showing the possibility of replacing conventional wet gas cleaning with a semi-dry gas cleaning approach.

Other papers | 2020

Development and experimental validation of a linear state-space model for absorption heat pumping systems for model-based control strategies

Zlabinger S, Unterberger V, Gölles M, Horn M, Wernhart M, Rieberer R. Development and experimental validation of a linear state-space model for absorption heat pumping systems for model-based control strategies. International Sorption Heat Pump Conference 2020.

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Control strategies of absorption heat pumping systems (AHPS, comprising heat pumps and chillers) often
perform insufficiently well, since they usually do not explicitly consider the systems’ dynamics and crosscoupling effects. One promising approach to improve their performance is to apply model-based control strategies since they would allow for an explicit consideration of these system characteristics. Therefore, mathematically simple models of the system to be controlled are required. This contribution proposes a new approach for such a model for a H2O-LiBr AHPS. The model results from the linearization of a more complex, nonlinear simulation model, leading to a simple, but physically still meaningful linear state-space model structure. The experimental validation shows that the developed model describes the system’s dynamics and cross-coupling effects sufficiently well and indicates that it is suitable to serve as a basis for the development of a model-based control strategy for AHPS.

Peer reviewed papers | 2017

Development and experimental validation of a water gas shift kinetic model for Fe-/Cr-based catalysts processing product gas from biomass steam gasification.

Kraussler M, Hofbauer H. Development and experimental validation of a water gas shift kinetic model for Fe-/Cr-based catalysts processing product gas from biomass steam gasification. Biomass Conversion and Biorefinery. Volume 7, Issue 2, 1 June 2017, Pages 153-165

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Peer reviewed papers | 2015

Development and validation of CFD models for gas phase reactions in biomass grate furnaces considering gas streak formation above the packed bed

Shiehnejadhesar A, Mehrabian R, Scharler R, Obernberger I. Development and validation of CFD models for gas phase reactions in biomass grate furnaces considering gas streak formation above the packed bed. Fuel Processing Technology. Volume 139, November 2015, Pages 142–158.

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State-of-the-art packed bed models supply continuous concentration profiles as boundary conditions for subsequent CFD simulations of gas phase, leading to pre-mixed combustion conditions. However, in reality the “porous” nature of the packed bed leads to streak formation influencing gas mixing and combustion. Therefore, in the present work, in order to account for the influence of the streaks on gas phase combustion, a gas streak model based on a correlation between the local gas residence time and a mixing time has been developed based on numerical simulations. Finally, the streak model was linked with an in-housed developed hybrid gas phase combustion model suitable for laminar to highly turbulent flow conditions and applied for an under-feed pellet stoker furnace (20 kWth) concerning the simulation of gas phase combustion and NOx formation. The results in comparison with a simulation without the streak formation model show that the flue gas species prediction can be improved with the proposed streak formation model. Especially, in the region above the fuel bed (in the primary combustion chamber), this is of special importance for NOx reduction by primary measures.

Peer reviewed papers | 2013

Development of a biomass heating device for low energy and passive houses

Schwabl M, Schwarz M, Figl F, Carvalho L, Staudinger M, Kalb W, et al. Development of a biomass heating device for low energy and passive houses. Management of Environmental Quality. 2013;24(5):652-66.

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urpose: Decreasing energy demand due to improved building standards requires the development of new biomass combustion technologies to be able to provide individual biomass heating solutions. The purpose of this paper is, therefore, the development of a pellet water heating stove with minimal emission at high thermal efficiency. Design/methodology/approach: The single components of a 10 kW water heating pellet stove are analysed and partly redesigned considering the latest scientific findings and experimental know-how in combustion engineering. The outcome of this development is a 12 kW prototype which is subsequently down-scaled to a 6 kW prototype. Finally, the results of the development are evaluated by testing of an accredited institute. Findings: Based on an existing pellet water heating stove, the total excess air ratio was reduced, a strict air staging was implemented and the fuel supply was homogenized. All three measures improved the operating performance regarding emissions and thermal efficiency. The evaluation of the development process showed that the CO emissions are reduced by over 90 per cent during full load and by 30-60 per cent during minimum load conditions. Emissions of particulate matter are reduced by 70 per cent and the thermal efficiency increased to 95 per cent. Originality/value: The result represents a new state of technology in this sector for minimal emissions and maximal thermal efficiency, which surpasses the directives of the Eco label "UZ37" in Austria and "Blauer Engel" in Germany, which are amongst the most stringent performance requirements in the European Union. Hence this design possesses a high potential as heating solution for low and passive energy houses. © Emerald Group Publishing Limited.

Conference presentations and posters | 2015

Development of a briquette stove with a candle burning principle - characteristics and measurement results

Kirchhof J, Schmidl C, Moser W, Haslinger W. Development of a briquette stove with a candle burning principle - characteristics and measurement results, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (visual presentation)

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Peer reviewed papers | 2018

Development of a compact technique to measure benzo(a)pyrene emissions from residential wood combustion, and subsequent testing in six modern wood boilers

Klauser F, Schwabl M, Kistler M, Sedlmayer I, Kienzl N, Weissinger A, Schmidl C, Haslinger W, Kasper-Giebl A. Development of a compact technique to measure benzo(a)pyrene emissions from residential wood combustion, and subsequent testing in six modern wood boilers. Biomass and Bioenergy. April 2018, 111: 288-300.

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Polycyclic aromatic hydrocarbons (PAHs) are emitted during incomplete combustion of organic materials and are particularly harmful to human health. As a representative of PAHs, Benzo(a)pyrene (BaP) is restricted by the European Union to an annual average value of 1 ng m−3 in ambient air. This threshold is significantly exceeded during the heating season in various regions. Residential wood combustion furnaces are considered to be a major source for BaP pollution.

In this research, a compact sampling method for BaP measurements was validated. Afterwards, the method was used to assess emissions from modern automatic wood boilers, in order to obtain a detailed knowledge of BaP emissions from residential wood combustion furnaces.

It was demonstrated that, for a wide range of BaP concentrations, sampling from the hot flue gas of residential wood combustors can be carried out effectively over a simple quartz filter, after proper dilution with cold purified air. Highest BaP emissions from the investigated boilers occurred during start, with a mean concentration value of 6.3 μg m-3. All values refer to standard conditions (273.15 °C, 100 kPa) and to an O2 volume fraction of 13% in the dry flue gas. The lowest concentrations occurred during full load operation (mean value 73 ng m-3 at STP). It was found that, amongst all flue gas compounds analysed, elemental carbon is the parameter most closely related to BaP. This work demonstrates, at optimal operating conditions, modern automatic wood boilers have potentially lowest BaP emission concentrations amongst residential wood combustion furnaces.

Other papers | 2014

Development of a gas phase combustion model suitable for low and high turbulence conditions

Shiehnejadhesar A, Mehrabian R, Scharler R, Goldin GM, Obernberger I. Development of a gas phase combustion model suitable for low and high turbulence conditions. Fuel. 2014;126:177-87.

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A novel hybrid gas phase combustion model suitable for low as well as high turbulent combustion conditions is proposed. In particular, in the region above the fuel bed of small-scale biomass combustion plants, gas phase mixing is highly influenced by laminar and low turbulence zones. Here, the eddy break-up combustion models are not valid because they were originally developed for highly turbulent flows. Therefore, a CFD gas phase reaction model applicable over the whole Reynolds range from laminar to turbulent flows is developed. It is a hybrid Eddy Dissipation Concept/finite rate kinetics model which calculates the effective reaction rate from laminar finite rate kinetics and the turbulent reaction rate and weights them depending on the local turbulent Reynolds number of the flow. To validate the proposed model, comparisons are made with experimental data for a series of jet flames covering laminar, transitional, and turbulent flow conditions. The simulation results show that the prediction of flame can be improved with the proposed hybrid combustion model. © 2014 Elsevier Ltd. All rights reserved.

Conference presentations and posters | 2019

Development of a New Method for Investigation of the Ash Melting Behavior in the Fluidized Bed Conversion Processes

Priscak J, Kuba M, Hofbauer H. Development of a New Method for Investigation of the Ash Melting Behavior in the Fluidized Bed Conversion Processes. ICPS 2019.

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Conference presentations and posters | 2015

Development of a new test method for defining a real life thermal heat output of firewood stoves

Sturmlechner R, Aigenbauer S, Moser W, Schmidl C, Reichert G, Stressler H, Schwabl M, Haslinger W. Development of a new test method for defining a real life thermal heat output of firewood stoves, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (visual presentation)

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Conference presentations and posters | 2014

Development of a new Type test method for residential wood combusiton (RWC) appliances focusing on real life operation

Reichert G, Schmidl C, Aigenbauer S, Figl F, Moser W, Stressler H, Haslinger W, Development of a new Type test method for residential wood combusiton (RWC) appliances focusing on real life operation, 22nd European Biomass Conference 2014, 23rd-26th of June 2014, Hamburg, Germany. p 373-380.

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Since batch-wise operated biomass roomheaters are claimed to cause high amounts of gaseous and particulate emissions effective measures for a reduction of these emissions especially in real life operation have to be implemented in the future. For a verification of the real life operation performance as well as for a better product differentiation of biomass room heating appliances on the market advanced testing methods will be necessary in the future. Therefore a new test method for roomheaters called “Stove Testing 2020” (ST2020) was developed. According to the new test method the emission and efficiency performance of roomheaters is determined under operating conditions that are closer to real life. Compared to the existing EN 13240 standard also transient combustion phases are included. For a final evaluation of the test method the reproducibility as well as the real life relevance was analysed by a Round-Robin-Test as well as by field tests. The results showed sufficient reproducibility as well as a high real life relevance of the ST2020 test method. However, due to the strong impact of user behavior on emission and efficiency performance in real life operation further technological improvements of biomass roomheaters have to be strongly supported by effective measures to guarantee a correct operation.

Master Thesis | 2024

Development of a simulation model for belt drying systems

Pichler, R. Development of a simulation model for belt drying systems, Master's Thesis. 2024.

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Conference presentations and posters | 2015

Development of a streak formation model for an improved prediction of gas phase combustion in biomass grate furnaces

Shiehnejadhesar A, Mehrabian R, Scharler R, Goldin GM, Obernberger I. Development of a streak formation model for an improved prediction of gas phase combustion in biomass grate furnaces, INFUB 10th European Conference on Industrial Furnace and Boilers 2015, 7th-10th of April 2015, Porto, Portugal.

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State-of-the-art packed bed models supply continuous concentration profiles as boundary conditions for subsequent CFD simulations of gas phase, leading to pre-mixed combustion conditions. However, in reality the “porous” nature of the packed bed leads to streak formation influencing gas mixing and combustion. Therefore, in the present work, in order to account for the influence of the streaks on gas phase combustion, a gas streak model based on a correlation between the local gas residence time and a mixing time has been developed based on numerical simulations. Finally, the streak model was linked with an in-housed developed hybrid gas phase combustion model suitable for laminar to highly turbulent flow conditions and applied for an under-feed pellet stoker furnace (20 kWth) concerning the simulation of gas phase combustion and NOx formation. The results in comparison with a simulation without the streak formation model show that the flue gas species prediction can be improved with the proposed streak formation model. Especially, in the region above the fuel bed (in the primary combustion chamber), this is of special importance for NOx reduction by primary measures.

Conference presentations and posters | 2013

Development of a test gas generator for biomass gasification derived process gas - a test methodology for quality insurance and development

Martini S, Kleinhappl M. Development of a test gas generator for biomass gasification derived process gas - a test methodology for quality insurance and development, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 775-777.

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Conference presentations and posters | 2012

Development of an empirical model to describe the local high temperature corrosion risk of 13CrMo4-5 steel in biomass CHP plants regarding the fuel wood chips

Gruber T, Schulze K, Scharler R, Oberberger I. Development of an empirical model to describe the local high temperature corrosion risk of 13CrMo4-5 steel in biomass CHP plants regarding the fuel wood chips, Conference Impacts of Fuel Quality on Power Production and Environment 2012, 23th-27th of September 2012, Puchberg, Austria.

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Conference presentations and posters | 2011

Development of biomass fired boilers with an advanced CFD model for ash deposit and aerosol formation

Schulze K, Scharler R, Obernberger I. Development of biomass fired boilers with an advanced CFD model for ash deposit and aerosol formation, 9th European Conference on Industrial Furnaces and Boilers 2011, 26th-29th of April 2011, Estoril, Portugal.

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Conference presentations and posters | 2014

Development of novel concepts for microalgae in the Austrian energy system

Sonnleitner A, Bacovsky D. Development of novel concepts for microalgae in the Austrian energy system, 4. Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

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Microalgae are seen worldwide as a new and promising feedstock for the energy supply chain.
Because of their high productivity and their ability to convert CO2 into biomass, microalgae are a
potential raw material for biorefineries, avoiding the food versus fuel conflict, and contributing to an
increased share of renewable energy. According to the current state of the art the utilization of algal
biomass for the production of fuel, energy and heat seems to be economically not competitive and the
life cycle assessment shows improvement possibilities in energy consumption (project
Algae&Energy:Austria). There are different options for utilization concepts which are technologically
and economically feasible. New concepts need to be developed and synergies with already existing
technologies need to be used.
Challenges along the value chain:
· Supply of water for cultivation
· Supply of nutrients for cultivation
· Energy consumption during cultivation
· Harvesting and processing of biomass
· Investment and operating costs
One possibility to cover the need of water and nutrients in a cost-effective way is the combination of
microalgae cultivation and waste water treatment. The cultivation of algae using different waste water
types common in Austria is technologically possible. In particular municipal waste water and effluents
from breweries and dairies are suitable as substrate. Due to the usage of this synergy the need for
fresh water and artificial fertilizer for algae cultivation decreases substantially and therefore operating
costs are reduced. Promising production concepts were developed and further research and
development needs were pointed out (project SAM).
After producing algal biomass the harvesting and processing steps for further utilization seem to be
difficult. In particular the high amount of water increases the energy expenditure in most of the
conversion pathways. Hydrothermal liquefaction seems to be promising to reduce the energy intensity
through two major factors: First, the conversion takes place in the liquid phase, and no energy
intensive drying of the algal biomass is needed. Second, the entire carbon which is fixed in the algae
can be used for energy production. The main product of hydrothermal liquefaction is a bio-oil, which
can be further processed in existing refinery processes into biogenic motor fuels, plastics and basic
chemicals (project microHTL).
In Austria many scientific research groups and companies are dealing with microalgae in the energy
system. These research and development efforts comprise different topics and approaches, like
different cultivation system designs (open pond, photobioreactor), biotechnological optimization of
microalgae species, the utilization of algal biomass in energetic and material pathways or the
combination of microalgae cultivation with existing technologies. It is of growing importance to
establish a network of Austrian experts and research groups for enhancement of cooperation and
research within the field of algae (project network biobased industry).
Through the optimization along the entire value chain with special regard to novel concepts of
cultivation, harvesting, processing, conversion and utilization, as well as an enhanced network of
Austrian experts and research groups, microalgae can serve as biogenic feedstock for the energy

Other papers | 2025

Development of Operational Parameters for Cashew Shell Gasification and Validation in a 1 MW aDFB Steam Gasifier

Hochstöger D, Huber M, Binder M, Valizadeh A, Fürsatz K, Kuba M, Aichernig C, Hofbauer H, Hannl TK. Development of Operational Parameters for Cashew Shell Gasification and Validation in a 1 MW aDFB Steam Gasifier. Energy and Fuels.2025.39(5):2630-2642.

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After years of development of the dual fluidized bed gasification process with woody biomass, new challenges arise with a wider range of feedstocks, such as agricultural residues or waste fractions, gaining importance. This work presents the results from the operation of a 1 MW advanced dual fluidized bed (aDFB) gasifier at the Syngas Platform Vienna, with cashew shells (CS) as feedstock and pure olivine or olivine mixed with 33% limestone as the bed material. Two operation points, different in their main process parameters, with CS as feedstock were performed for a minimum of 16 h. Due to the high calorific value (22.7 MJ/kg dry) and high content of volatile components (81.7 wt % dry), CS are well suited for gasification. During the operation, a product gas with a H2/CO ratio of 1.93–2.29 was produced, which suits the use of the syngas as input for Fischer–Tropsch synthesis. Due to the low ash softening temperature of CS of about 840 °C, determined in ash fusion tests and predicted by thermodynamic equilibrium calculations, the operating temperature in the gasifier was kept below 820 °C in the first operation point with around 20 h of runtime. Bed material samples after the operation revealed the formation of agglomerates, which were analyzed by SEM and EDS for their morphology and composition. During the second operation point, temperatures in the gasifier were increased to 870 °C for 16 h, while no agglomeration tendencies were observed. Both operations did not show changes in fluidization behavior compared to operations with wood chips (WC). The evaluated key performance indicators were compared to aDFB steam gasification of WC as the reference.

Reports | 2024

Development of outlook for the necessary means to build industrial capacity for drop-in advanced biofules

Final Report

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Biofuels are crucial for reducing emissions in the transport sector, contributing significantly to the objectives of the Fit for 55 package and climate neutrality goals. This role is anticipated to grow in the future as advanced biofuels become increasingly accessible. This expansion will be driven by the full commercial-scale development of technologies, processes, and value chains, supported by ambitious policies and sector-specific targets that will encourage their deployment.

Conference presentations and posters | 2010

Development of process routes for synthetic biofuels from biomass (BTL)

Weber G, Potetz A, Rauch R, Hofbauer H. Development of process routes for synthetic biofuels from biomass (BTL), 18th European Biomass Conference and Exhibiton 2010, 3rd-7th May 2010, Lyon, France. p 1829-1833.

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In Güssing a nearly nitrogen free product gas can be provided by the Fast Internal Circulating Fluidized Bed (FICFB) – gasification system. The main components of the product gas are hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4). A Fischer – Tropsch (FT-) trial plant uses the product gas components H2 and CO in an exothermic, catalytic reaction to produce hydrocarbon chains. Catalysts based on iron and cobalt are used for the synthesis. In Güssing a slurry reactor is used for low temperature FT – synthesis. The main parts of the plant are the gas cleaning section, the gas compression section, the FT – slurry reactor and the product separation section. In the year 2008 eight experiments with a catalyst based on iron and from April to July 2009 ten experiments with a catalyst based on cobalt were done. Over 1400 operating hours were reached and approximately 170 kg of FT – raw product was produced. The product of the experiments with cobalt catalyst was split into the fractions naphtha, diesel and waxes by vacuum distillation. The long chain waxes of the distillation were used in a hydro – treater to convert them to diesel.

Other Publications | 2012

Development of the 1MW Bio-SNG plant, evaluation on technological and economical aspects and upscaling considerations

Rehling, B. Development of the 1MW Bio-SNG plant, evaluation on technological and economical aspects and upscaling considerations, Ph.D. Thesis, Vienna University of Technology, Vienna, Austria, 2012.

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Conference presentations and posters | 2020

Die Donau - Eine Chance für die Bioenergiebranche?

Dißauer C, Strasser C. Die Donau - Eine Chance für die Bioenergiebranche? 6th Central European Biomass Conference, 2020, Graz.

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Conference presentations and posters | 2008

Die Situation der energetischen Nutzung von Stroh in Österreich

Eder G, Haslinger W, Wörgetter M. Die Situation der energetischen Nutzung von Stroh in Österreich, Fachtagung Strohenergie 2008, 29th-30th of March, Jena, Deutschland.

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Peer reviewed papers | 2021

Digestate as Sustainable Nutrient Source for Microalgae—Challenges and Prospects

Bauer L, Ranglová K, Masojidek J, Drosg B, Meixner K. Digestate as Sustainable Nutrient Source for Microalgae—Challenges and Prospects. Applied Sciences. 2021.11(3):1056

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The interest in microalgae products has been increasing, and therefore the cultivation industry is growing steadily. To reduce the environmental impact and production costs arising from nutrients, research needs to find alternatives to the currently used artificial nutrients. Microalgae cultivation in anaerobic effluents (more specifically, digestate) represents a promising strategy for increasing sustainability and obtaining valuable products. However, digestate must be processed prior to its use as nutrient source. Depending on its composition, different methods are suitable for removing solids (e.g., centrifugation) and adjusting nutrient concentrations and ratios (e.g., dilution, ammonia stripping). Moreover, the resulting cultivation medium must be light-permeable. Various studies show that growth rates comparable to those in artificial media can be achieved when proper digestate treatment is used. The necessary steps for obtaining a suitable cultivation medium also depend on the microalgae species to be cultivated. Concerning the application of the biomass, legal aspects and impurities originating from digestate must be considered. Furthermore, microalgae species and their application fields are essential criteria when selecting downstream processing methods (harvest, disintegration, dehydration, product purification). Microalgae grown on digestate can be used to produce various products (e.g., bioenergy, animal feed, bioplastics, and biofertilizers). This review gives insight into the origin and composition of digestate, processing options to meet requirements for microalgae cultivation and challenges regarding downstream processing and products.

Conference presentations and posters | 2012

Direct Heating with Logwood ‐ State of the Art, Opportunities and Challenges

Schmidl C, Haslinger W. Direct Heating with Logwood ‐ State of the Art, Opportunities and Challenges, 20th European Biomass Conference 2012, 18th-22nd of June 2012, Milano, Italy.

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PhD Thesis | 2023

Distributed Optimization Methods for Energy Management Systems

Kaisermayer V. Distributed Optimization Methods for Energy Management Systems. 2023.

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Efficient control of energy systems is an important factor in achieving the CO2-emission goals. District heating (DH) networks are an especially relevant example of such energy systems. State-of-the-art control of small and medium-sized DH networks, however, still mainly relies on simple rule-based control concepts. Handling future challenges such as varying prices and intermittent renewable production is difficult to achieve with such control concepts. Optimization-based energy management systems (EMS) are a promising high-level control approach for the efficient operation of DH networks and complex energy systems in general. An especially interesting challenge arises when DH networks grow, as often the opportunity arises to interconnect them. However, if they operated by different owners, the control task becomes challenging, especially for optimization-based EMS. This is because, in the overall objective function, the cost and revenue for any exchange of energy would cancel out. This thesis presents a solution to this challenge. The main focus of this thesis is on the application of distributed optimization methods for EMS in the context of coupled energy systems, operated by multiple owners, especially interconnected DH networks. The presented methods and ideas are evaluated on a practical application of three DH networks in Austria.  

Reports | 2023

District Heating and Cooling Networks in an Integrated Energy System Context (Guidebook)

Final Report of the IEA DHC Annex TS3

Böhm H, Cronbach D, Muschick D, Ianakiev A, Jentsch A, Cadenbach A, Kranzl L, Reuter S, Rossi J, Schmidt RR, Sorknaes P, Svensson IL, Trier D, Tunzi M, Widl E. IEA DHC Annex TS3 Guidebook, District Heating and Cooling in an Integrated Energy System Context, 2023.

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Annex TS3: Hybrid Energy Networks

The aim of the IEA DHC Annex TS3 „hybrid energy networks" is to promote opportunities and to overcome challenges for district heating and cooling (DHC) networks in an integrated energy system context, focusing on the coupling to the electricity and the gas grid.

 

Other Publications | 2012

Domestic Heating with Biomass – State‐of‐the‐Art and Strategic Research Needs

Haslinger W. Domestic Heating with Biomass – State‐of‐the‐Art and Strategic Research Needs, Annual Conference Renewable Heating and Cooling 2012, 26th-27th of April 2012, Copenhagen, Denmark.

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Peer reviewed papers | 2016

Dominating high temperature corrosion mechanism in low alloy steels in wood chips fired boilers

Gruber T, Retschitzegger S, Scharler R, Obernberger I. Dominating high temperature corrosion mechanism in low alloy steels in wood chips fired boilers. Energy and Fuels. 17 March 2016;30(3): 2385-2394.

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Ash related problems such as slagging, fouling, and high temperature corrosion in biomass fired boilers are still insufficiently explored due to the complexity of the underlying processes. High temperature corrosion of low alloy steels like 13CrMo4-5 has already been investigated in plants firing chemically untreated wood chips. In this earlier work it has been suggested that the oxidation of the steel is the dominating mechanism in the material temperature range between 450 and 550 °C. Unfortunately the exponential dependence of the material degradation on the flue gas temperature also found within this work cannot be explained with the proposed corrosion mechanism. To determine the dominating corrosion mechanism, additionally test runs have been carried out in a specially designed drop tube reactor. To investigate the time-dependent corrosion behavior of 13CrMo4-5, a newly developed mass loss probe was applied under several constant parameter setups. In addition to these measurements, the time-dependent oxidation of 13CrMo4-5 under air was investigated in a muffle furnace. To gain relevant information regarding the corrosion mechanism prevailing, the deposits as well as the corrosion products have been examined subsequently to the test runs by means of scanning electron microscopy and energy dispersive X-ray analyses. With the experimental data gained it could be shown that the dominating corrosion mechanism strongly depends on the conditions prevailing (e.g., steel temperature, flue gas temperature, and velocity) and can either be the oxidation of the steel by gaseous O2 and H2O or a combination of oxidation and active Cl-induced oxidation.

Peer reviewed papers | 2019

Double-cropping systems based on rye, maize and sorghum: Impact of variety and harvesting time on biomass and biogas yield

Wannasek L, Ortner M, Kaul HP, Amon B, Amon T. Double-cropping systems based on rye, maize and sorghum: Impact of variety and harvesting time on biomass and biogas yield. European Journal of Agronomy 2019.110:125934

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Climate change affects the frequency and intensity of extreme weather, the results of which include production losses and climate-induced crop productivity fluctuations.

Double-cropping systems (DCSs) have been suggested as a way to increase biomass-production while simultaneously delivering environmental benefits. In a three-year field-test, two DCSs based on maize and sorghum as the main crop and rye as the preceding winter crop were compared with each other and compared with 2 single-cropping systems (SCSs) of maize or sorghum; there were comparisons of growth dynamics, optimal harvesting and growing time as well as biomass and methane yield. In addition, the impact of variety and harvest time on the winter rye optimal biomass yield was studied.

The experiments clearly showed the superiority of the DCS over the SCS. Within the DCS, the rye/sorghum combination achieved significantly higher biomass yields compared to those of the rye/maize combination. The highest dry matter biomass yield was achieved during year 1 at 27.5 ± 2.4 t∙ha−1, during which winter rye contributed 8.3 ± 0.7 t∙ha−1 and sorghum contributed 19.2 ± 1.8 t∙ha−1. At the experimental location, which is influenced by a Pannonia climate (hot and dry), the rye/sorghum DCS was able to obtain average methane yields per hectare, 9300 m3, whereas the rye/maize combination reached 7400 m3. In contrast, the rye, maize and sorghum SCSs achieved methane yields of 4800, 6100 and 6500 m3 ha−1, respectively. The study revealed that the winter rye and sorghum DCS is a promising strategy to counteract climate change and thus guarantee crop yield stability.

Peer reviewed papers | 2021

Drivers and barriers in retrofitting pulp and paper industry with bioenergy for more efficient production of liquid, solid and gaseous biofuels: A review.

Mäki E, Saastamoinen H, Melin K, Matschegg D, Pihkola H. Drivers and barriers in retrofitting pulp and paper industry with bioenergy for more efficient production of liquid, solid and gaseous biofuels: A review. Biomass and Bioenergy. 2021.106036. https://doi.org/10.1016/j.biombioe.2021.106036

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Ample interest for more efficient utilization of bio-based residues has emerged in the Nordic pulp and paper (P&P) industry, which uses virgin wood as feedstock. Although different bioenergy retrofit technologies for production of liquid, solid, and gaseous bioenergy products have been applied in the existing P&P mills, the number of installations remains small. The lack of profound knowledge of existing bioenergy retrofits hinders the replication and market uptake of potential technologies. This review synthesises the existing knowledge of European installations and identifies the key drivers and barriers for implementation to foster the market uptake of potential technologies. The bioenergy retrofits were reviewed in terms of technical maturity, drivers, barriers and market potential. Based on this evaluation, common drivers and barriers towards wider market uptake were outlined from political, economic, social, technical, environmental, and legal perspective. Technologies already commercially applied include anaerobic fermentation of sludge, bark gasification, tall oil diesel and bioethanol production, whereas lignin extraction, biomethanol production, hydrothermal liquefaction and hydrothermal carbonization are being demonstrated or first applications are under construction. The findings of this review show that a stable flow of residues at P&P mills creates a solid base for retrofitting. New innovative bio-based products would allow widening the companies' product portfolios and creating new businesses. Also, European Union's (EU) legislation drives towards advanced biofuels production. Wider uptake of the retrofitting technologies requires overcoming the barriers related to uncertainty of economic feasibility and unestablished markets for new products rather than technical immaturity. 

Conference presentations and posters | 2013

Dual fluidized bed gasification: operational experiences and future developments

Wilk V, Hofbauer H. Gasification Technologies: Delivering the Potential, Workshop “Dual fluidized bed gasification: Operational experiences and future Developments”, 23rd of October, Newcastle, England, 2013.

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Conference presentations and posters | 2020

Dual fluidized bed steam gasification of biomass – the basic technology for a broad product portfolio

Kuba M. Dual fluidized bed steam gasification of biomass – the basic technology for a broad product portfolio. 6th Central European Biomass Conference (oral presentation). 2020.

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Conference presentations and posters | 2012

Dynamic modeling of biomass pellet boilers

Schnetzinger R, Hebenstreit B, Schwarz M, Höftberger E. Dynamic modeling of biomass pellet boilers, World Bioenergy, 29th-31st of May 2012, Jönköping, Sweden.

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Other Publications | 2013

Dynamic modelling of hydronic heating systems supplied by a biomass boiler for residential application: solutions for the optimization of the control strategy

Rimoldi, M. Dynamic modelling of hydronic heating systems supplied by a biomass boiler for residential application: solutions for the optimization of the control strategy, Master Thesis, Polytechnic University of Milan, Milan, Italy, 2013.

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Other papers | 2020

Dynamische Simulation von Absorptionskälteanlagen – Dymola-Modell einer H2O/LiBr-Absorptionskälteanlage

Wernhart M, Rieberer R, Zlabinger S, Unterberger V, Gölles M. Dynamische Simulation von Absorptionskälteanlagen: Dymola-Modell einer H2O/LiBr-Absorptionskälteanlage. in Proc. Deutsche Kälte-Klima-Tagung 2020. Deutscher Kälte- und Klimatechnischer Verein e.V. 2020

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Absorptionskälteanlagen können einen wesentlichen Beitrag zur Verringerung von CO2-Emissionen leisten, wenn Wärme aus regenerativen Energieträgern oder Abwärme aus industriellen Prozessen zum Antrieb verwendet wird. Absorptionskälteanlagen weisen bereits jetzt eine hohe Effizienz auf, bei veränderlichen Betriebsbedingungen kann diese je nach vorhandenen Stellgliedern weiter gesteigert werden. Dazu werden im Rahmen des Forschungsprojektes „Heat Pumping Systems Control (HPC)“ zwei Absorptionskälteanlagen – eine mit der Stoffpaarung Ammoniak/Wasser (NH3/H2O) und eine mit der Stoffpaarung Wasser/Lithiumbromid (H2O/LiBr) – untersucht, um für unterschiedliche Anwendungen optimale Betriebsstrategien zu entwickeln. Zur Berücksichtigung der Zustandsänderungen in der Absorptionskälteanlage, werden dynamische Simulationsmodelle in der Modellierungssprache Modelica entwickelt und mit Messdaten validiert.

Im Rahmen dieses Konferenzbeitrags werden Komponentenmodelle für die NH3/H2O-Absorptionskälteanlage und Simulationsrechnungen bei veränderlichen Randbedingungen präsentiert, sowie ein Vergleich mit Messdaten diskutiert.

Peer reviewed papers | 2023

Early layer formation on K-feldspar during fluidized bed combustion with phosphorus-rich fuel

Faust R, Fürsatz K, Aonsamang P, Sandberg M, Kuba M, Skoglund N, Pavleta Knutsson. Early layer formation on K-feldspar during fluidized bed combustion with phosphorus-rich fuel. Fuel. January 2023.331:125595.

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K-feldspar was utilized as bed material for fluidized bed combustion of bark, chicken manure, and their mixture. Bed samples were extracted after 4 and 8 h and the samples were analyzed with scanning electron microscopy to study the impact of P-rich chicken manure on the bed material. The results were compared to fixed bed exposures with different orthophosphates to investigate their influence in detail.

The fresh bed material used for this study exhibited an uneven surface with many cavities which facilitated the deposition and retention of the fuel ash. Utilizing pure chicken manure as fuel led to the formation of Ca- and P-rich particles which accumulated in these cavities. At the same time, larger ash particles were formed which consisted of the elements found in chicken manure ash. The co-combustion of bark and chicken manure led to the interaction of the two ash fractions and the formation of a thicker ash layer, which consisted of elements from both fuel ashes, namely Ca, P, Si, K and S. The layer appeared to be partially molten which could be favorable for the deposition of ash particles and thereby the formation of a mixed Ca/K-phosphate. Fixed bed exposures of the K-feldspar particles with Na3PO4 or K3PO4 caused particle agglomeration which means presence of alkali-phosphates should be limited.

The co-combustion of bark with chicken manure showed promising results both regarding a shift from Ca-phosphates to more bioavailable Ca/K-phosphates and an acceleration in ash layer formation. The formation of an ash layer after only 4 h of exposure with the mixture of bark and chicken manure could be advantageous for catalytic activation of the bed material.

Peer reviewed papers | 2015

Econometric analysis of the wood pellet market in Austria

Kristöfel C, Strasser C, Morawetz U, Schmid E. Econometric analysis of the wood pellet market in Austria. 12th International Conference On The European Energy Market, 20-22 May 2015. 20 August 2015, Lisbon, Portugal.

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Conference presentations and posters | 2014

Economic and ecological comparison of torrefaction-based biomass supply chains in Central Europe

Ehrig R, Kristöfel C, Rauch P, Strasser C, et al. Economic and ecological comparison of torrefaction-based biomass supply chains in Central Europe, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

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Studien | 2024

Economic and environmental assessment of the retrofitting of a first-generation ethanol Plant

Susmozas A, Matschegg D, Davidis B, Spekreijse J, Tzelepi V, Kourkoumpas D, Alonso J, Coto B, Iglesias R. Economic and environmental assessment of the retrofitting of a first-generation ethanol plant. Biomass Conversion and Biorefinery.20 June 2024

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Bioenergy retrofitting may be a short-term strategy to promote the transition from first-generation to advanced bioethanol, as it could improve the cost-competitiveness of the latter. In addition, this strategy could also extend the operational lifetime of first-generation ethanol plants, whose production is restricted by the current European renewable energy regulations. Therefore, this work evaluates two retrofitting scenarios of an existing corn-based first-generation ethanol facility located in Spain from an economic and environmental perspective. In the first case (scenario 1), advanced bioethanol was produced using industrial waste streams included in the Renewable Energy Directive II. The second approach (scenario 2) involves the integration of second-generation technology into the existing first-generation facility. The economic analysis shows that scenario 1 presents a low capital expenditure (CAPEX, €100,000), as it only requires the installation of an industrial waste storage tank. Although, in terms of net present value (NPV), the CAPEX of scenario 2 is higher. It obtains better profitability reaching an NPV of approximately €25,610,000. The environmental assessment identified natural gas consumption as the main contributor to the overall score of the global warming impact category. Consequently, the increased energy demand of the retrofit scenarios, mainly linked to second-generation technology, has a negative impact in terms of greenhouse gas emissions. Therefore, a key aspect to improve the environmental performance of these scenarios would be the replacement of natural gas with a more sustainable alternative, such as bio-based gases.

Peer reviewed papers | 2024

Economic and environmental assessment of the retrofitting of a first‑generation ethanol plant

Susmozas A, Matschegg D, Davidis B, Spekreijse J, Tzelepi V, Kourkoumpas DS, García Alonso JM, Coto B, Iglesias R. Economic and environmental assessment of the retrofitting of a first‑generation ethanol plant. Biomass Conversion and Biorefinery. 20 June 2024. doi: 10.1007/s13399-024-05826-5

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Bioenergy retrofitting may be a short-term strategy to promote the transition from first-generation to advanced bioethanol, as it could improve the cost-competitiveness of the latter. In addition, this strategy could also extend the operational lifetime of first-generation ethanol plants, whose production is restricted by the current European renewable energy regulations. Therefore, this work evaluates two retrofitting scenarios of an existing corn-based first-generation ethanol facility located in Spain from an economic and environmental perspective. In the first case (scenario 1), advanced bioethanol was produced using industrial waste streams included in the Renewable Energy Directive II. The second approach (scenario 2) involves the integration of second-generation technology into the existing first-generation facility. The economic analysis shows that scenario 1 presents a low capital expenditure (CAPEX, €100,000), as it only requires the installation of an industrial waste storage tank. Although, in terms of net present value (NPV), the CAPEX of scenario 2 is higher. It obtains better profitability reaching an NPV of approximately €25,610,000. The environmental assessment identified natural gas consumption as the main contributor to the overall score of the global warming impact category. Consequently, the increased energy demand of the retrofit scenarios, mainly linked to second-generation technology, has a negative impact in terms of greenhouse gas emissions. Therefore, a key aspect to improve the environmental performance of these scenarios would be the replacement of natural gas with a more sustainable alternative, such as bio-based gases.

Peer reviewed papers | 2025

Economic and environmental assessment of the retrofitting of a first‑generation ethanol plant

Susmozas A, Matschegg D, Davidis B, Spekreijse J, Tzelepi V, Kourkoumpas DS, García Alonso JM, Coto B, Iglesias R. Economic and environmental assessment of the retrofitting of a first‑generation ethanol plant. Biomass Conversion and Biorefinery. March 2025. 15:8997-9010.

External Link Details

Bioenergy retrofitting may be a short-term strategy to promote the transition from first-generation to advanced bioethanol, as it could improve the cost-competitiveness of the latter. In addition, this strategy could also extend the operational lifetime of first-generation ethanol plants, whose production is restricted by the current European renewable energy regulations. Therefore, this work evaluates two retrofitting scenarios of an existing corn-based first-generation ethanol facility located in Spain from an economic and environmental perspective. In the first case (scenario 1), advanced bioethanol was produced using industrial waste streams included in the Renewable Energy Directive II. The second approach (scenario 2) involves the integration of second-generation technology into the existing first-generation facility. The economic analysis shows that scenario 1 presents a low capital expenditure (CAPEX, €100,000), as it only requires the installation of an industrial waste storage tank. Although, in terms of net present value (NPV), the CAPEX of scenario 2 is higher. It obtains better profitability reaching an NPV of approximately €25,610,000. The environmental assessment identified natural gas consumption as the main contributor to the overall score of the global warming impact category. Consequently, the increased energy demand of the retrofit scenarios, mainly linked to second-generation technology, has a negative impact in terms of greenhouse gas emissions. Therefore, a key aspect to improve the environmental performance of these scenarios would be the replacement of natural gas with a more sustainable alternative, such as bio-based gases.

Conference presentations and posters | 2012

Economic boundary conditions for the successful operation of active condensation systems

Hebenstreit B, Höftberger E. Economic boundary conditions for the successful operation of active condensation systems, World Bioenergy 2012, 29th-31st of May 2012, Jönköping, Sweden.

Details

In this study the economic boundary conditions for successful active condensation systems are evaluated.
The concept of active condensation utilizes the flue gas enthalpy exiting the boiler by combining a quench for flue gas condensation and a heat pump. Through the heat pump the flue gas can be cooled down below the dew point of the water vapor. Therefore, the sensible heat as well as the latent heat of water can be recovered. This study evaluates the economic viability  for  different  test  cases.  On  the  one  hand  pellet  boilers  of  small  (10kW)  and  medium  (100kW)  size  are considered. On the other hand wood chip boilers of medium (100kW) and big (10MW) size are studied. The economic analysis shows a decrease in operating costs between 2% and 13%. The payback time is evaluated on a net present value (NPV) method, showing a payback time of 2-10 years for the large scale system and approx. 10-35 years for the medium sized ones.

Conference presentations and posters | 2013

Economic Comparison of Torrefaction-Based and Conventional Pellet Production-to-End-Use Chains

Ehrig R, et al. Economic Comparison of Torrefaction-Based and Conventional Pellet Production-to-End-Use Chains, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 1342-1349.

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Biomass upgrading through torrefaction is expected to relevantly reduce biomass trade costs and thus energy costs for the end-user. In this framework, the present work aims at defining crucial technical and cost parameters for the production, fuel properties, supply and end-use of torrefied pellets. The findings are used to compare four real-case wood pellet with corresponding torrefied pellet supply chains. Input data are derived from laboratory fuel, pelletising and storage experiments with torrefied biomass provided from European producers, cost estimations based on experience from related technology engineering and set-up as well as from expert consultations. This allows a step-by-step comparison of cost advantages and additional expenses from pretreatment to end-user. As a result, torrefied pellets turn out to be a certain alternative for wood pellets. The cost comparison demonstrates that the production of torrefied pellets is still much more cost-intensive, but can be partly compensated by reduced transportation costs. At the end-user, heat production in small-scale pellet boilers is technically feasible, but with slightly higher costs. Co-firing torrefied pellets in large-scale coal plants can be cost-competitive to industrial wood pellets, when no additional retrofit and operation and maintenance costs incur.

Peer reviewed papers | 2014

Economics and price risks in international pellet supply chains

Ehrig R, Behrendt F, Wörgetter M, Strasser C. Economics and price risks in international pellet supply chains. International Pellet Supply Chains. ISBN 978-3-319-07015-5. 2014.

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Peer reviewed papers | 2021

Effect of biomass fuel ash and bed material on the product gas composition in DFB steam gasification

Fürsatz K, Fuchs J, Benedikt F, Kuba M, Hofbauer H. Effect of biomass fuel ash and bed material on the product gas composition in DFB steam gasification. Energy. 2021.219:119650.

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Gasification is a thermochemical process that transforms carbonaceous matter into a gaseous secondary energy carrier, referred to as product gas. This product gas can be used for heat and power generation but also for syntheses. One possible gasification technology suitable for further synthesis is dual fluidised bed (DFB) steam gasification. The H2:CO ratio, which determines the suitability of the product gas for further synthesis, is influenced by the catalytic activity inside the gasification reactor. Eleven DFB steam gasification experiments were performed comparing the catalytic activity for various bed material and fuel combinations. The bed materials used were K-feldspar, fresh and layered olivine, and limestone, and the fuels gasified were softwood, chicken manure, a bark–chicken manure mixture and a bark-straw-chicken manure mixture. The water-gas-shift (WGS) equilibrium deviation was used to evaluate the catalytic activity inside the gasification reactor. It was shown that both the fuel ash and bed material have an effect on the catalytic activity during gasification. Scanning electron microscopy and energy dispersive X-ray spectrometry showed the initial layer formation for experiments with ash-rich fuels. Isolated WGS experiments were performed to further highlight the influence of bed material, fuel ash and fuel ash layers on the WGS equilibrium.

Peer reviewed papers | 2017

Effect of draught conditions and ignition technique on combustion performance of firewood roomheaters

Reichert G, Hartmann H, Haslinger W, Öhler H, Mack R, Schmidl C, Schön C, Schwabl M, Stressler H, Sturmlechner R, Hochenauer C. Effect of draught conditions and ignition technique on combustion performance of firewood roomheaters. Renewable Energy. 1 May 2017;105: 547-560.

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Firewood roomheaters are popular, widespread and important for reaching European CO2 emission targets. Since they contribute significantly to local air pollution, they have to be optimized towards minimal emission release, especially in real-life operation. Draught conditions and user behavior, particularly the ignition technique, significantly affect the emission and efficiency performance of firewood roomheaters. This study assessed the effects of the respective parameters experimentally. The results revealed a clear correlation between draught conditions and thermal efficiency. Increased draught conditions up to 48 Pa significantly decreased thermal efficiency by 6%–11% absolutely. However, for gaseous emissions no clear trend was observed. Accordingly, CO and OGC emissions increased at higher draught conditions for one tested roomheater by 30% and 60%, but decreased for two other tested roomheaters by 13%–45%. For PM emissions no effect of increased draught conditions was evident. Top-down ignition technique did not lead to a significant decrease of PM emissions compared to bottom-up ignition. In contrast, bottom-up ignition led to best thermal efficiencies. The use of either spruce or beech as kindling material revealed no significant relevance for the ignition performance.

Peer reviewed papers | 2023

Effect of time-dependent layer formation on the oxygen transport capacity of ilmenite during combustion of ash-rich woody biomass

Priscak J, Valizadeh A, Öhman M, Hofbauer H, Kuba M. Effect of time-dependent layer formation on the oxygen transport capacity of ilmenite during combustion of ash-rich woody biomass. Fuel. 1 December 2023. 353:129068

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Oxygen carrier aided combustion (OCAC) is a novel technology that aims to enhance combustion of heterogenous fuels by replacing the inert bed material with an active oxygen carrier. One of the promising oxygen carriers is natural ilmenite which shows decent oxygen transport capacity and mechanical stability under OCAC operating conditions. However, interactions between ilmenite and woody biomass ash lead to the formation of a calcium-rich ash layer, which affects the ability of the oxygen carrier (OC) to transfer oxygen throughout the boiler and subsequently decreases the combustion efficiency. This paper focuses on the time-dependent morphological and compositional changes in ilmenite bed particles and the consequence effects on the oxygen transport capacity and reactivity of ilmenite. Ilmenite utilized in this study was investigated in a 5 kW bubbling fluidized bed combustion unit, utilizing ash-rich bark pellets as fuel. A negative effect of iron migration on the oxygen transport capacity was observed in ilmenite bed particles after 6 h of operation in the bubbling fluidized bed reactor. The decrease in the oxygen transport capacity of ilmenite was found to correlate with the increased exposure time in the fluidized bed reactor and was caused by the migration and subsequent erosion of Fe from the ilmenite particles. On the other hand, the older bed particles show an increase in reaction rate, presumably due to the catalytic activity of the calcium-enriched outer layer on the bed particle surface.

Peer reviewed papers | 2019

Effects of partial maize silage substitution with microalgae on viscosity and biogas yields in continuous AD trials

Gruber-Brunhumer MR, Montgomery LFR, Nussbaumer M, Schoepp T, Zohar E, Muccio M, Ludwig I, Bochmann G, Fuchs W, Drosg B. Effects of partial maize silage substitution with microalgae on viscosity and biogas yields in continuous AD trials. Journal of Biotechnology 2019;295:80-89.

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The microalga Acutodesmus obliquus was investigated as a feedstock in semi-continuously fed anaerobic digestion trials, where A. obliquus was co-digested with pig slurry and maize silage. Maize silage was substituted by both 10% and 20% untreated, and 20% ultrasonicated microalgae biomass on a VS (volatile solids) basis. The substitution of maize silage with 20% of either ultrasonicated and untreated microalgae led to significantly lower biogas yields, i.e., 560 dm³ kg−1 VScorr in the reference compared to 516 and 509 dm³ kg-1VScorr for untreated and ultrasonicated microalgae substitution. Further, the viscosities in the different reactors were measured at an OLR of 3.5 g VS dm-3 d-1. However, all treatments with microalgae resulted in significantly lower viscosities. While the mean viscosity reached 0.503 Pa s in the reference reactor, mean viscosities were 53% lower in reactors where maize was substituted by 20% microalgae, i.e. 0.239 Pa s, at a constant rotation speed of 30 rpm. Reactors where maize was substituted by 20% ultrasonicated microalgae had a 32% lower viscosity, for 10% microalgae substitution a decrease of 8% was measured. Decreased viscosities have beneficial effect on the bioprocess and the economy in biogas plants. Nonetheless, with regard to other parameters, no positive effect on biogas yields by partial substitution with microalgae biomass was found. The application of microalgae may be an interesting option in anaerobic digestion when fibrous or lignocellulosic substances lead to high viscosities of the digested slurries. High production costs remain the bottleneck for making microalgae an interesting feedstock.

Other Publications | 2015

Effects of pretreatment and storage methods on biomethane potential of different microalgae in anaerobic digestion

Gruber M, Jerney J, Zohar E, Nussbaumer M, Hieger C, Bochmann G, Schagerl M, Obbard JP, Fuchs W, Drosg B. Effects of pretreatment and storage methods on biomethane potential of different microalgae in anaerobic digestion, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (oral presentation)

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Peer reviewed papers | 2020

Effects of Pyrolysis Conditions and Feedstocks on the Properties and Gasification Reactivity of Charcoal from Woodchips

Phounglamcheik A, Wang L, Romar H, Kienzl N, Broström M, Ramser K, Skreiberg Ø, Umeki K. Effects of Pyrolysis Conditions and Feedstocks on the Properties and Gasification Reactivity of Charcoal from Woodchips. Energy and Fuels. 2020;34(7):8353-8365.

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Pyrolysis conditions in charcoal production affect yields, properties, and further use of charcoal. Reactivity is a critical property when using charcoal as an alternative to fossil coal and coke, as fuel or reductant, in different industrial processes. This work aimed to obtain a holistic understanding of the effects of pyrolysis conditions on the reactivity of charcoal. Notably, this study focuses on the complex effects that appear when producing charcoal from large biomass particles in comparison with the literature on pulverized biomass. Charcoals were produced from woodchips under a variety of pyrolysis conditions (heating rate, temperature, reaction gas, type of biomass, and bio-oil embedding). Gasification reactivity of produced charcoal was determined through thermogravimetric analysis under isothermal conditions of 850 °C and 20% of CO2. The charcoals were characterized for the elemental composition, specific surface area, pore volume and distribution, and carbon structure. The analysis results were used to elucidate the relationship between the pyrolysis conditions and the reactivity. Heating rate and temperature were the most influential pyrolysis parameters affecting charcoal reactivity, followed by the reaction gas and bio-oil embedding. The effects of these pyrolysis conditions on charcoal reactivity could primarily be explained by the difference in the meso- and macropore volume and the size and structural order of aromatic clusters. The lower reactivity of slow pyrolysis charcoals also coincided with their lower catalytic inorganic content. The reactivity difference between spruce and birch charcoals appears to be mainly caused by the difference in catalytically active inorganic elements. Contrary to pyrolysis of pulverized biomass, a low heating rate produced a higher specific surface area compared with a high heating rate. Furthermore, the porous structure and the reactivity of charcoal produced from woodchips were influenced when the secondary char formation was promoted, which cannot be observed in pyrolysis of pulverized biomass.

Peer reviewed papers | 2012

Effects of pyrolysis conditions on the heating rate in biomass particles and applicability of TGA kinetic parameters in particle thermal conversion modelling.

Mehrabian R, Scharler R, Obernberger I. Effects of pyrolysis conditions on the heating rate in biomass particles and applicability of TGA kinetic parameters in particle thermal conversion modelling. Fuel. 2012;93:567-75.

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A one-dimensional single particle model is utilised to investigate the effects of radiation temperature, moisture content, particle size and biomass physical properties on the heating rate in biomass particles during pyrolysis. The model divides the particle into four layers - drying, pyrolysis, char and ash layer - corresponding to the four main stages of biomass thermal conversion. The average of the time derivative of the pyrolysis layer centre temperature weighted by the pyrolysis rate is introduced as an appropriate indicator for the heating rate in the particle during pyrolysis. The influencing parameters on the heating rate are summarised in the Biot number and the thermal time constant, to make the investigation of their effects easier. The heating rate is inversely proportional to the thermal time constant. The effect of a variation of the Biot number on the heating rate is negligible in comparison to the thermal time constant. Therefore, the thermal time constant can be sufficiently used to specify the heating rate regimes during pyrolysis. It is found that for thermal time constants of more than 50 s, pyrolysis takes place in a low heating rate regime, i.e. less than 50 K/min. Additionally, the heating rate during pyrolysis of various biomass types under a wide range of thermal conversion conditions has been examined, in order to classify the heating rate regime of pyrolysis in state-of-the-are combustion/gasification plants. The pyrolysis of wood dust and wood pellets is found to happen always in high heating rate regimes. Therefore, the kinetic parameters obtained by conventional TGA systems (typically with heating rates lower than 50 K/min) are not applicable for them. On the contrary, the pyrolysis of wood logs always happens in low heating rate regimes, which indicates that kinetic parameters obtained by conventional TGA systems can be applied. However, pyrolysis of wood chips can undergo low or high heating rate regimes depending on their particle size. Concerning the moisture content, it can be stated that it does not strongly influence the heating rate regime of certain biomass particles. © 2011 Elsevier Ltd. All rights reserved.

Conference presentations and posters | 2021

Effects of varying comminution techniques and pyrolysis temperatures on the particle shape of pyrolyzed wood powders and its implications on fluidisation behaviour

Deutsch R, Krammer G, Strasser C, Kienzl N. Effects of varying comminution techniques and pyrolysis temperatures on the particle shape of pyrolyzed wood powders and its implications on fluidisation behaviour. 29th European Biomass Conference and Exhibition, EUBCE 2021, 26-29 April 2021. 2021.

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Iron production via blast furnace utilizes coal and coke to reduce iron oxides which results in high greenhouse gas emissions. Biomass-based reducing agents may reduce its fossil carbon footprint. Charcoal as bioreducer has been since the beginning of steelmaking. In order to obtain a reducing agent which is appropriately fluidizable for pulverized coal injection (PCI), the most influential powder characteristics must be named and the influence of thermal pre-treatment and comminution technique on particle properties have to be examined. The aim is to show that particle shape design of a grinding product is feasible to a certain extent by varying mill types and how pyrolyzed wood powder properties technically relevant for powder conveying processes can be influenced .

Peer reviewed papers | 2015

Efficiency and operational behaviour of small-scale pellet boilers installed in residential buildings

Carlon E, Schwarz M, Golicza L, Verma VK, Prada A, Baratieri M, et al. Efficiency and operational behaviour of small-scale pellet boilers installed in residential buildings. Appl Energy 2015;155:854-865.

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Conference presentations and posters | 2014

Efficiency criteria for pellet heating systems

Schmidl C. Efficiency criteria for pellet heating systems, European Pellet Conference 2014, 26th-28th of February 2014, Wels, Austria.

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Peer reviewed papers | 2014

Efficient anaerobic mono-digestion of N-rich slaughterhouse waste: Influence of ammonia, temperature and trace elements

Ortner M, Leitzinger K, Skupien S, Bochmann G, Fuchs W. Efficient anaerobic mono-digestion of N-rich slaughterhouse waste: Influence of ammonia, temperature and trace elements. Bioresour Technol. 2014;174:222-32.

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Three mono-digestion experiments treating slaughterhouse waste with high TKN concentration (~11. g/kg) were applied in lab-scale at mesophilic and psychrophilic conditions to study the impact of high ammonia concentrations and additives. Precipitation of sulphur by addition of ferrous chloride did not influence process behaviour, whereas supplementation of trace elements significantly improved process stability by reducing volatile fatty acid concentration towards zero.The limit of NH4-N concentration causing a rise of VFAs to 19,000mg/l and reduction of methane by 25% was found between 7.7 and 9.1g/kg which correspond to NH3 concentrations of 830-1060mg/l.Psychrophilic operation (25°C) lowered inhibitory NH3 concentration to 140mg/l, but process performance was stable only at low OLR of 0.4kgVS/m3d.Robust performance at highest possible NH4-N concentration (7.7g/kg), low VFA accumulation and satisfying methane yield of about 280Nm3/t COD was observed at OLR of 2.5kgVS/m3d at 37°C. © 2014 Elsevier Ltd.

Conference presentations and posters | 2010

Efficient biomass utilisation by polygeneration processes - Production of hydrogen, electricity and heat

Mayer T. Efficient biomass utilisation by polygeneration processes - Production of hydrogen, electricity and heat, ICPS 2010, 7th-9th of September 2010, Leipzig, Germany.

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A polygeneration process is about to be implemented at the biomass gasification plant in Oberwart, Austria. Apart from conventional heat and electricity production, product gas obtained from steam gasification of wood chips is used for production of hydrogen. A membrane separation process was chosen for this application. Meeting the requirements of robustness and simplicity are benefits of this technology, however, maximizing of purity and output of hydrogen is not given highest priority. Simulation results show the gas compositions of both permeate and retentate stream as a function of different membrane stage-cuts. Basically high hydrogen content in the permeate stream can be achieved, but only with the drawback of low stage-cuts. Moreover, the trade-off between hydrogen purity and hydrogen recovery as well as the influence of the operating pressure on the purity are illustrated.

Reports | 2024

Efficient Gathering, Storing, Distributing and Validation of Data

Feierl L, Putz S, Unterberger V, Mortada M.S, Pandian Y, Jensen A.R, Natiesta T, Mehnert S, Tschopp D, Ohnewein P. Efficient Gathering, Storing, Distributing and Validation of Data. This is a report from SHC Task 68: Efficient Solar District Heating and work performed in Subtask B: Data Preparation & Utilization. Published: 24.01.2024. Report number, DOI: 10.18777/ieashc-task68-2024-0001.

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Solar thermal plants have proven to be a successful player in providing heat for district heating networks. However, to ensure the efficient operation of such plants and to achieve optimal coordination with other heat generation units, thorough monitoring, quality control, and system control are required. These tasks strongly depend on accessible and reliable measurement data, which are often unavailable.

Thus, this report focuses on efficient data gathering, storage, distribution, and validation, covering data
management topics- from sensor selection to permanent data storage. The report is mainly targeted at system designers and plant operators, aiming to provide checklists and recommendations on these topics.

The report considers a general solar district heating plant, as depicted by IEA SHC Task 55  – including a collector field, heat storage, and heating center (including a biomass boiler, heat pump, and other auxiliary heating) up to the interface to the district heating network. The topics are described on a summary level of detail while referring the reader to individual articles in case more information is needed. In addition, research groups may use this report to get an overview of data management in the solar-thermal field and identify related work.

The work consists of five sections: The Required Data section lists recommended measurements and discusses meta information required to interpret the data successfully. The Data Gathering section provides recommendations for data logging – e.g., sampling rate, encoding, and formatting. The Data-Distribution section shows proven examples of architectures for collecting and distributing data. Furthermore, the Data Storage section describes what data storage technologies (e.g., CSV files or relational databases) are currently used. The section also discusses the experiences, advantages, and challenges of the respective technologies. Finally, the Data Validation section lists common data-validation procedures that can be applied to solar-thermal data and links to open-source implementations where available.

Peer reviewed papers | 2019

Efficient Multi-Year Economic Energy Planning in Microgrids

Pecenak Z, Stadler M, Fahy K, Efficient Multi-Year Economic Energy Planning in Microgrids. Applied Energy 2019;225.

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With energy systems, the problem of economic planning is decisive in the design of a low carbon and resilient future grid. Although several tools to solve the problem already exist in literature and industry, most tools only consider a single “typical year” while providing investment decisions that last around a quarter of a century. In this paper, we introduce why such an approach is limited and derive two approaches to correct this. The first approach, the Forward-Looking model, assumes perfect knowledge and makes investment decisions based on the full planning horizon. The second novel approach, the Adaptive method, solves the optimization problem in single year iterations, making incremental investment decisions that are dependant on previous years, with only knowledge of the current year. Comparing the two approaches on a realistic microgrid, we find little difference in investment decisions (maximum 21% difference in total cost over 20 years), but large differences in optimization time (up to 12000% time difference). We close the paper by discussing implications of forecasting errors on the microgrid planning process, concluding that the Adaptive approach is a suitable choice.

Peer reviewed papers | 2019

Efficient Multi-Year Economic Energy Planning in Microgrids

Pecenak Zachary K, Stadler M,Fahy K. Efficient Multi-Year Economic Energy Planning in Microgrids. Applied Energy Journal by Elsevier, ISSN: 0306-2619

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With energy systems, the problem of economic planning is decisive in the design of a low carbon and resilient future grid. Although several tools to solve the problem already exist in literature and industry, most tools only consider a single “typical year” while providing investment decisions that last around a quarter of a century. In this paper, we introduce why such an approach is limited and derive two approaches to correct this. The first approach, the Forward-Looking model, assumes perfect knowledge and makes investment decisions based on the full planning horizon. The second novel approach, the Adaptive method, solves the optimization problem in single year iterations, making incremental investment decisions that are dependant on previous years, with only knowledge of the current year. Comparing the two approaches on a realistic microgrid, we find little difference in investment decisions (maximum 21% difference in total cost over 20 years), but large differences in optimization time (up to 12000% time difference). We close the paper by discussing implications of forecasting errors on the microgrid planning process, concluding that the Adaptive approach is a suitable choice.

Conference presentations and posters | 2009

Efficient utilisation of industrial residues and waste with high biomass content using gasification technology

Wilk V, Hofbauer H. Efficient utilisation of industrial residues and waste with high biomass content using gasification technology, 18th European Biomass Conference and Exhibiton 2010, 3th-7th of May 2010, Lyon, France. p 544-547.

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Conference presentations and posters | 2017

Effizienzsteigerung und Optimierung des Zusammenspiels von Scheitholzkessel, Pufferspeicher und Solaranlage durch die Verwendung mathematischer Modelle

Schulz J, Zemann C, Gölles M. Effizienzsteigerung und Optimierung des Zusammenspiels von Scheitholzkessel, Pufferspeicher und Solaranlage durch die Verwendung mathematischer Modelle. 5th Central European Biomass Conference (oral presentation). January 2017, Graz, Austria.

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Other Publications | 2013

Einfluss der thermo-chemischen Vorbehandlung von Biertrebern auf die anaerobe Fermentation

Bochmann, G. Einfluss der thermo-chemischen Vorbehandlung von Biertrebern auf die anaerobe Fermentation, Ph.D. Thesis, Universität für Bodenkultur Wien, Vienna, Austria, 2013.

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Gegenstand der Arbeit ist der thermische und thermo-chemische Aufschluss von Biertrebern. Dabei werden die Prozessbedingungen wie Chemikalien, Konzentration, Aufschlusstemperatur sowie Aufschlussdauer und deren Einfluss auf die Biogasgewinnung untersucht. Der Nachweis erfolgt entlang den einzelnen Prozessstufen Hydrolyse, Acidogenese und Methanogenese. Die Prozessparameter der Aufschlüsse haben sowohl einen starken Einfluss auf die Hydrolyse der Lignozellulose als auch auf die Bildung thermischer Nebenprodukte. Diese Zwischenprodukte beeinflussen unter anderem den Schritt der Acidogenese stark. Wohingegen die Endprodukte, Melanoidine, anaerob kaum abbaubar sind und damit die Biogasausbeute reduzieren. Die höchsten Methanerträge werden mit einer Behandlungstemperatur von 140 °C erreicht. Unterschiedlich sind dabei die Höhe der zusätzlichen Gaserträge von 28 Vol.-% mit H2O sowie rund 50 Vol.-% mit Lauge und 60 Vol.-% mit Säure. In semi-kontinuierlich beschickten Reaktoren konnten mit unbehandelten Trebern Erträge von 410 m³N CH4/Mg oTS realisiert werden. Thermisch aufgeschlossene Treber ergeben Erträge von 468 m³N CH4/Mg oTS (+14 %). Durch die Zugabe von Lauge zum thermischen Aufschluss kann der Methanertrag auf 558 m³N/Mg oTS (+36 %) gesteigert werden. Auf Grund der Prozessinstabilitäten war der acido-thermisch aufgeschlossene Treber nicht auswertbar. Der Mehrertrag in den Aufschlüssen ist auf die verbesserte Verwertung der Zellulose und Hemizellulose zurückzuführen. Durch die Vorbehandlung der Biertreber gelingt es, die Treberverwertung wirtschaftlicher zu gestalten. Nach der Vergütung im Österreichischen Ökostromgesetz 2012 können Erträge von bis 13 €/Mg FM Treber erreicht werden. Dies ist insbesondere durch eine thermo-chemischen Vorbehandlung möglich

Other Publications | 2012

Einfluss von Holzart und Rohstoff auf die Entstehung von Emissionen von Holzpellets während der Lagerung

Schmutzer-Rosender, I. Einfluss von Holzart und Rohstoff auf die Entstehung von Emissionen von Holzpellets während der Lagerung, Master Thesis, Universität für Bodenkultur Wien, Vienna, Austria, 2012.

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Als feste biogene Brennstoffe gewinnen Pellets durch ihre hohe Energiedichte, ihre gleichbleibende Qualität und die wachsende Nachfrage immer mehr an Bedeutung. Bei der Lagerung von Holzpellets werden Emissionen frei, welche aus Abbaureaktionen von Holzbestandteilen entstehen. Es gibt bereits einige Publikationen, welche das Auftreten und die Zusammensetzung dieser Emissionen in Pelletslagern beschreiben. Es fehlen jedoch noch jegliche Nachweise zur Klärung der ursächlichen Reaktionen, weshalb die Untersuchung der Emissionen aus Pellets und deren Rohstoffen erforderlich ist.
Im Zuge dieser Arbeit werden daher zunächst die Freisetzungsraten von Kohlenmonoxid (CO) und flüchtigen organischen Verbindungen (VOC) verschiedener Holzrohstoffe und Pellets in Lagerungsversuchen untersucht. Des Weiteren erfolgt die Bestimmung des organischen Extraktstoffgehaltes dieser Holzproben mittels Soxhletextraktion. Anschließend werden diese Charakteristika einander gegenübergestellt, um mögliche Zusammenhänge zu identifizieren. Bei den untersuchten Holzarten handelt es sich um die Gemeine Fichte (Picea abies), die Europäische Lärche (Larix decidua) sowie um die Weihrauchkiefer (Pinus taeda). Von diesen drei Holzarten werden verschiedene Späne und Pellets miteinander verglichen. Zudem werden unterschiedliche am österreichischen Markt erhältliche Pellets untersucht. Die höchste Freisetzung von CO wird bei frischen Kieferpellets mit 2,88 mg CO/kg Brennstoff (BS) absolute Trockenmasse (atro)/d gemessen. Die geringste Menge an CO wird von einer handelsüblichen Pelletsprobe mit 0,02 mg CO/kg BS atro/d emittiert. Allen untersuchten Holzproben ist gemein, dass in den Lagerungsversuchen höhere Mengen an CO als an VOC freigesetzt werden. Der organische Extraktstoffgehalt der Kieferproben ist am höchsten. Der geringste organische Extraktstoffgehalt tritt bei den Fichtenhobelspänen auf. Bei allen Proben wird festgestellt, dass der organische Extraktstoffgehalt mit der Pelletierung abnimmt. Zudem wird bestimmt, dass sich mit zunehmender Trocknungstemperatur der organische Extraktstoffgehalt verringert. Ein eindeutiger Zusammenhang zwischen Extraktstoffgehalt und freigesetzten Emissionsmengen kann nicht hergestellt werden.

Conference presentations and posters | 2009

Einsatz der sensorgestützten Sortiertechnik zur Senkung des Brennwerts der Deponiefraktion in MBA Anlagen

Faist V, Ragossnig A. Einsatz der sensorgestützten Sortiertechnik zur Senkung des Brennwerts der Deponiefraktion in MBA Anlagen, Waste-to-Ressources 2009, 5th-8th of May 2009, Hannover, Deutschland.

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Other Publications | 2022

Einsatz von Aschen aus Biomassefeuerungen in der Forst- und Landwirtschaft

Retschitzegger S. Einsatz von Aschen aus Biomassefeuerungen in der Forst- und Landwirtschaft. Seminar - Effizienter Heizwerkbetrieb. March 2022

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Other Publications | 2024

ELLIPSE - Valorising Pulp and Paper Residues

Pummer R, Bauer L, Neubauer M, Prall K, Drosg B. ELLIPSE - Valorising Pulp and Paper Residues

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Peer reviewed papers | 2018

Emission characterisation of modern wood stoves under real-life oriented operating conditions

Klauser F, Carlon E, Kistler M, Schmidl C, Schwabl M, Sturmlechner R, Haslinger W, Kasper-Giebl A. Emission characterisation of modern wood stoves under real-life oriented operating conditions. Atmospheric Environment 2018;192:257-266.

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The quality of emission inventories substantially bases on the reliability of used emission factors (EFs). In this work EFs were studied according to recently published characterization methods, called “beReal”, reflecting real life operating conditions in Europe. EFs for four pellet stoves and nine firewood appliances (roomheaters and cookers) of carbon monoxide (CO), organic gaseous compounds (OGC), nitrogen oxides, total solid particles (TSP) of hot and of diluted flue gas, total, elemental and organic carbon (TC, EC, OC) and benzo(a)pyrene were determined.

CO, OGC, TSPs, TC, EC and OC emissions from firewood appliances were significantly higher than for pellet stoves, indicating the high relevance of classifying appliances according to the operation type. TSP sampled from diluted flue gas at 40 °C (28 mg MJ−1 to 271 mg MJ−1 based on fuel input) was higher than TSP sampled from hot flue gas (21 mg MJ−1 to 70 mg MJ−1). This reveals the high relevance of sampling conditions for the determination of real life emissions. Benzo(a)pyrene emissions scattered over a wide range (0.5 μg MJ−1 to 129.8 μg MJ−1) indicating high sensitivity to unfavorable combustion conditions. Therefore a higher number of experimentally determined emissions factors could improve the reliability of EFs for inventories. CO emissions measured in beReal tests were substantially higher than official type tests, thus showing that type testing results provide limited information for the determination of real life emissions.

A systematic evaluation of EFs with defined real life methods like beReal would substantially improve the reliability of emission inventories.

Peer reviewed papers | 2017

Emission factor assessment for two firewood stoves in the autumn or spring season

Sturmlechner R, Stressler H, Schwabl M, Reichert G, Carlon E, Haslinger W, Schmidl C, Weissinger A. Emission factor assessment for two firewood stoves in the autumn or spring season. 25th International Conference on Modelling, Monitoring and Management of Air Pollution. 25-27 April 2017.

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This study analyses the emission factors of two firewood room heaters under testing conditions which emulate real life operation. A 6.5 kW stove with low heat storage capacity and high leakage rate (stove A) is compared with an 8 kW air-tight stove with high heat storage capacity (stove B). Thermal efficiency, carbon monoxide (CO) and organic gaseous compound (OGC) emissions, as well as the thermal heat losses (THL) during cool down phase were investigated in a series of laboratory tests. Furthermore, the influence of closing the air supply dampers at the end of the heating cycle was evaluated. Test results for the whole test cycle (including cool down phase) showed that stove A had CO emissions of 2633 mg/MJOutput and OGC emissions of 203 mg/MJOutput, while stove B had CO emissions of 2408 mg/MJOutput and OGC emissions of 109 mg/MJOutput, when air dampers were closed. It was also found that user behaviour has a critical influence on the stoves’ performance. Closing the air supply dampers at the end of the stove operation improved the efficiency by up to 5.0 percentage points. Furthermore, the duration of the cool down phase increased, as well as CO and OGC emissions decreased. As a matter of fact, measures to improve the user behaviour as for example user trainings and accurate manuals are of major importance in order to decrease emissions and increase efficiency of domestic heating appliances. Moreover, real life emission factors of other technologies should be established in order to develop a database which can be applied in air quality dispersion models.

Peer reviewed papers | 2021

Emission minimization of a top-lit updraft gasifier cookstove based on experiments and detailed CFD analyses

Scharler R, Archan G, Rakos C, von Berg L, Lello D, Hochenauer C, Anca-Couce A. Emission minimization of a top-lit updraft gasifier cookstove based on experiments and detailed CFD analyses. Energy Conversion and Management. 2021.247:114755.

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Around 2.7 billion people worldwide have no access to clean cooking equipment, which leads to major health problems due to high emissions of unburned products (VOC, CO and soot). A top-lit updraft gasifier cookstove with forced draft was identified as the technology with the highest potential for reducing harmful emissions from incomplete combustion in simple cookstoves. The basic variant of the stove was equipped with a fan for efficient mixing of product gas with air and fired with pellets to increase the energy density of low-grade residues. The development was conducted based on water boiling test experiments for wood and rice hull pellets and targeted CFD simulations of flow, heat transfer and gas phase combustion with a comprehensive description of the reaction kinetics, which were validated by the experiments. Emphasis was put on the reduction of CO emissions as an indicator for the burnout quality of the flue gas. The optimisation was carried out in several steps, the main improvements being the design of a sufficiently large post-combustion chamber and a supply of an appropriate amount of primary air for a more stable fuel gasification. The experiments showed CO emissions <0.2 g/MJdel for wood and rice hull pellets, which corresponds to a reduction by a factor of about 15 to 20 compared to the basic forced draft stove concept. Furthermore, these values are between 5 and 10 times lower than published water boiling test results of the best available cookstove technologies and are already close to the range of automatic pellet furnaces for domestic heating, which are considered to be the benchmark for the best possible reduction of CO emissions.

Other Publications | 2016

Emission Reduction of Firewood Roomheaters by Optimization of Operating Conditions and Catalyst Integration

Reichert G, Stressler H, Schmidl C, Schwabl M, Sturmlechner R, Haslinger W. Emission Reduction of Firewood Roomheaters by Optimization of Operating Conditions and Catalyst Integration. 24th European Biomass Conference & Exhibition (oral presentation). June 2016, Amsterdam, Netherlands.

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Conference presentations and posters | 2015

Emission Reduction of Firewood Stoves by Integrated Honeycomb Catalysts

Reichert G, Schmidl C, Schwabl M, Sedlmayer I, Stressler H, Sturmlechner R, Wöhler M, Haslinger W. Emission Reduction of Firewood Stoves by Integrated Honeycomb Catalysts, Word Sustainable Energy Days next 2015, 24th-27th of February 2015, Wels, Austria.

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Conference presentations and posters | 2014

Emissions from Biomass Boilers - The State of the Art

Schwabl M. Emissions from Biomass Boilers - The State of the Art, Wood Heating Conference, Newcastle 2015, 21st of November 2014, Newcastle, England.

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Conference presentations and posters | 2013

Emissions from Wood Pellets During Storage Referring to the Extractive Content

Schmutzer-Rosendeder I, Emhofer W, Haslinger W. Emissions from Wood Pellets During Storage Referring to the Extractive Content, Word Sustainable Energy Days next 2013, 27th-28th of February 2013, Wels, Austria.

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Wood pellets and wood raw materials such as chips or sawdust emit hazardous gases such as carbon monoxide (CO) and volatile organic compounds (VOCs) during processing and storage. Due to the high toxicity of CO it is necessary to identify the release mechanisms for CO and VOCs. Several studies show that organic extractives decrease during storage as well as the emissions. Therefore, the purpose of this study was to investigate a possible correlation between the organic extractive content and the release of CO and VOCs. Sawdust and pellets from Norway spruce (Picea abies), European larch (Larix decidua) and loblolly pine (Pinus taeda) were examined. Additionally, five different pellet samples from Austrian pellet producers were investigated. Soxhlet extraction with acetone was used to extract the organic content. The concentration of CO and VOCs was measured from stored wood materials and pellets in sealed glass flasks. The highest (3,41 mg CO/kg sample dm/d) and the lowest (0,02 mg CO/kg sample dm/d) release of CO were reported with freshly produced pine pellets and a spruce pellets sample from an Austrian do-it-yourself store, respectively. The results showed that the pelletizing process reduced the content of organic extractives. The emissions of pine samples concerning CO and VOCs were higher than of the spruce and larch samples. Moreover, the organic extractive content also decreased in that order. However, a direct correlation between organic extractive content and released quantities of emissions could not be established.

Peer reviewed papers | 2012

Emissionsfaktoren und chemische Charakterisierung von Feinstaubemissionen moderner und alter Biomasse-Kleinfeuerungen über typische Tageslastverläufe

Kelz J, Brunner T, Obernberger I. Emission factors and chemical characterisation of fi ne particulate emissions from modern and old residential biomass heating systems determined for typical load cycles. Environmental Sciences Europe. 2012;24(3).

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Conference presentations and posters | 2014

Empirical analysis of biomass and energy price volatility

Kristöfel C, Strasser C, Morawetz U, Schmid E. Empirical analysis of biomass and energy price volatility. Schriften der GEWISOLA. 2014;49:385-386. (peer reviewed) (visual presentation)

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The current debate on biomass price volatility mainly refers to increased market dynamics and integration as well as renewable energy policy intervention. Higher price volatility leads to additional costs that are often transmitted along the supply chain to the final consumers. We empirically analyze whether or not price volatility of woody biomass commodities has increased in recent years. Results indicate that the price volatility of some woody biomass
commodities has increased, but it is still lower than of fossil fuels.

Reports | 2021

Endbericht: Heat Pumping system Control (HPC)

Modellbasierte Regelung von Absorptionswärmepump-Anlagen.

Zlabinger S, Wernhart M, Unterberger V, Rieberer R, Gölles M, Rohringer C, Poier H, Halmdienst C, Kemmerzehl C, Otto M. Heat Pumping system Control (HPC). Modellbasierte Regelung von Absorptionswärmepump-Anlagen. FFG, 4. Ausschreibung Energieforschungsprogramm, Projektnummer: 865095. Endbericht. 2021.

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Other papers | 2016

Energetische Verwertung einer Feinfraktion aus der MBA durch pyrolytische Behandlung

Meirhofer M, Wartha C, Strasser C. Energetische Verwertung einer Feinfraktion aus der MBA durch pyrolytische Behandlung. Recy & DepoTech 2016 (poster). November 2016, Leoben, Austria.

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Other Publications | 2022

Energiegemeinschaften im Tourismussektor

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Der Leitfaden „Energiegemeinschaften im Tourismus“ zeigt, welche Möglichkeiten Energiegemeinschaften für Tourismusbetriebe, ihre Beschäftigten und Menschen, die in Tourismusregionen leben, bieten können und wie eine Energiegemeinschaft ins Leben gerufen werden
kann.

Reports | 2021

Energiespeicher in Österreich

Marktentwicklung 2020

Biermayr P, Aigenbauer St, Enigl M, Fink C, Knabl S, Leonhartsberger K, Matschegg D, Prem E, Strasser C, Wittmann M. Energiespeicher in Österreich Marktentwicklung 2020. 2021

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Conference presentations and posters | 2020

Energy Communities – Four Austrian Pioneering Initiatives: Microgrid Lab – Wieselburg

Zellinger M, Aigenbauer S, Stadler M. Energy Communities – Four Austrian Pioneering Initiatives: Microgrid Lab – Wieselburg. Mission Innovation Austria Online. 13 May 2020.

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Other Publications | 2013

Energy independent food processing industry -- realization of an innovative waste & energy management concept

Ortner M, Pröll T, Schumergruber A, Fuchs W. Energy independent food processing industry - realization of an innovative waste & energy management concept, Beijing International Environmental Technology Conference 2013, 21st-23rd of October 2013, Beijing, China.

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Other papers | 2024

Energy Knowledge Transfer To The Next Generation - Project "Energie und I"

Oberbauer C, Enigl M, Aigenbauer S. Energy Knowledge Transfer To The Next Generation - Project "Energie und I". Centre's Day 2024

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Peer reviewed papers | 2015

Energy self-supply of large abattoir by sustainable waste utilisation based on anaerobic mono-digestion

Ortner M, Wöss D, Schumergruber A, Pröll T, Fuchs W. Energy self-supply of large abattoir by sustainable waste utilisation based on anaerobic mono-digestion. Applied Energy. 2015;143:460-471.

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Abattoirs have a large number of energy intensive processes. Beside energy supply, disposal costs of animal by-products (ABP) are the main relevant cost drivers. In this study, successful implementation of a new waste and energy management system based on anaerobic digestion is described. Several limitations and technical challenges regarding the anaerobic digestion of the protein rich waste material had to be overcome. The most significant problems were process imbalances such as foaming and floatation as well as high accumulation of volatile fatty acids and low biogas yields caused by lack of essential microelements, high ammonia concentrations and fluctuation in operation temperature. Ultimately, 85% of the waste accumulated during the slaughter process is converted into 2700 MW h thermal and 3200 MW h electrical energy in a biogas combined heat and power (CHP) plant. The thermal energy is optimally integrated into the production process by means of a stratified heat buffer. The energy generated by the biogas CHP-plant can cover a significant share of the energy requirement of the abattoir corresponding to 50% of heat and 60% of electric demand, respectively. In terms of annual cost for energy supply and waste disposal a reduction of 63% from 1.4 Mio € to about 0.5 Mio € could be achieved with the new system. The payback period of the whole investment is approximately 9 years. Beside the economic benefits also the positive environmental impact should be highlighted: a 79% reduction of greenhouse gas emissions from 4.5 Mio kg CO2 to 0.9 Mio kg CO2 annually was achieved. The realized concept received the Austrian Energy Globe Award and represents the first anaerobic mono-digestion process of slaughterhouse waste worldwide.

Conference presentations and posters | 2013

Enhanced flue gas condensation technology: analysis of a 10MW demonstration plant

Hebenstreit B, Höftberger E, Ohnmacht R, Lundgren J, Toffolo A. Enhanced flue gas condensation technology: analysis of a 10MW demonstration plant, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 1614-1617.

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Peer reviewed papers | 2016

Enhanced Separation of the Organic Fraction from Paper Mill Effluent for Energy Recovery

Stoyanova E, Bochmann G, Couperus A, Fuchs W. Enhanced Separation of the Organic Fraction from Paper Mill Effluent for Energy Recovery. Waste and Biomass Valorization. 1 October 2016;7(5): 1031-1039.

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Other Publications | 2015

Entwicklung eines modellbasierten Optimierungsalgorithmus für die Wärmeversorgung mit Biomassefeuerungen

Oberlechner, F. Entwicklung eines modellbasierten Optimierungsalgorithmus für die Wärmeversorgung mit Biomassefeuerungen, Master Thesis, Technische Universität Graz, Graz, Austria, 2015.

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Wärmeversorgungsanlagen von Gebäuden, bestehend aus Biomasse-Feuerung, Solarkollektoren, Pufferspeicher, Heizkreis und Warmwasserzapfstellen gewinnen aufgrund ihrer Nachhaltigkeit zunehmend an Bedeutung. In den letzten Jahren wurden insbesondere für eine effiziente Regelung der Biomasse-Feuerung sehr gute Konzepte entwickelt. Diese können jedoch zumeist aufgrund unzureichender, übergeordneter Systemregelungen nicht ihr volles Potential ausschöpfen. In ihrer primitivsten Ausführung schaltet eine Systemregelung die Biomasse-Feuerung anhand der Ladehöhe des Pufferspeichers aus und ein. Diese Art der Regelung hat unweigerlich viele Ein-/ Ausschaltvorgänge der Feuerung, sowie eine schlechte Ausnutzung des solaren Eintrags zur Folge. Insbesondere bei Biomasse-Feuerungen sind Ein-/ Ausschaltvorgänge äußerst unwirtschaftlich und führen zu stark erhöhten Schadstoffemissionen. Die häufigen Ein-/ Ausschaltvorgänge verursachen zusätzlich erhöhte Wartungs- und Betriebskosten und schlussendlich eine verkürzte Lebensdauer zahlreicher Komponenten. Um die Ein-/ Ausschaltvorgänge zu minimieren und den solaren Eintrag zu steigern, soll im Rahmen dieser Arbeit ein übergeordnetes, modellprädiktives Regelungskonzept für die gesamte Wärmeversorgungsanlage entwickelt werden. Nach einer theoretischen Einführung in gemischt-ganzzahlige Optimalsteuerungsprobleme sowie ausgewählter Lösungsmethoden werden Prädiktionsmodelle für alle Komponenten der Wärmeversorgungsanlage entwickelt. Aufbauend auf den mathematischen Modellen für die einzelnen Komponenten der Anlage wird eine nichtlineare modellprädiktive Regelung entwickelt. Diese berücksichtigt zusätzlich Wetterprognosen sowie die erwartete Lastabnahme und führt schlussendlich zu einer Minimierung des Brennstoffverbrauchs sowie der Anzahl der Ein-/ Ausschaltvorgänge. Den Abschluss der Arbeit bilden ausführliche Simulationsstudien mit unterschiedlichen Wetterszenarien sowie Vergleiche mit herkömmlichen Regelungsstrategien.  

Other Publications | 2024

Environmental impact of the Sustainable Aviation Fuel FT-SPK from biomass gasification

Matschegg D, Fuhrmann M, Bacovsky D, Strasser C, Stern T. Environmental impact of the Sustainable Aviation Fuel FT-SPK from biomass gasification. Centre's Day 2024

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Peer reviewed papers | 2017

Environmental trade-offs between residential oil-fired and wood pellet heating systems: forecast scenarios for Austria until 2030

Karner K, Kristöfel C, Enigl M, Strasser C, Schmid E. Environmental trade-offs between residential oil-fired and wood pellet heating systems: forecast scenarios for Austria until 2030. Renewable & Sustainable Energy Reviews. December 2017;80: 868-879.

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Conference presentations and posters | 2017

ErgoS – Energierückgewinnung durch offene Sorption für Biomassefeuerungsanlagen

Höftberger E, Riepl R, Hebenstreit B, Golicza L, Paar EK, Goritschnig M, Zweiler R, Hochenauer C. ErgoS – Energierückgewinnung durch offene Sorption für Biomassefeuerungsanlagen. Güssing 17 Konferenz. March 2017, Güssing, Austria.

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Conference presentations and posters | 2020

Erneuerbare in Österreich - Die Marktdiffusion im Lichte der Klima- und Energieziele

Biermayr P, Leonhartsberger K, Dißauer C; Eberl M, Enigl M, Fechner H, Lukas Fischer L, Fürnsinn B, Moidl S, Schmidl C, Strasser C, Weiss W, Wonisch P, Wopienka E. Erneuerbare in Österreich - Die Marktdiffusion im Lichte der Klima- und Energieziele. EnInnov 2020, 16. Symposium Energieinnovation (oral presentation). 2020.

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Other Publications | 2024

Estimation and Prediction of the Drying State of a Herb Drying Process

Dovjak M, Niederwieser H, Staudt S, Hollenstein C, Gölles M, Gruber P, Rotter N, Pfleger J, Weiß W. Estimation and Prediction of the Drying State of a Herb Drying Process. Centre's Day 2024

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