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Conference contributions | 2013

Steam gasification of challenging fuels in the dual fluidized bed gasifier

Wilk V, Hofbauer H. Steam gasification of challenging fuels in the dual fluidized bed gasifier, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark.

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In order to enlarge the range of feedstock for the dual fluidized bed (DFB) gasification process, the influence of several fuel properties was studied in the 100 kW DFB pilot plant. Fuels with high concentration of nitrogen and sulfur, fuels with an increased concentration of fine particles, and fuels with extremely high content of volatiles were tested. The DFB gasification system is found to be robust and can handle all the materials. Nitrogen, sulfur and chlorine from the fuel are predominantly converted in the gasification reactor, either to gases (nitrogen, sulfur) or bound to ash (chlorine, sulfur). For the performance of the DFB gasifier, sufficient contact of fuel, product gas and bed material is important. Increasing amounts of fine particles or volatiles in the fuels lead to higher tar loads in the product gas, because the residence time of fuel particles in bubbling fluidized bed is shorter.


Conference contributions | 2012

Steigerung des Jahreswirkungsgrads von Pelletsheizungen

Schmidl C. Steigerung des Jahreswirkungsgrads von Pelletsheizungen, 12. Industrieforum Pellets 2012, 9th-10th of October 2012, Berlin, Germany.

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Books / Bookchapters | 2013

Storage and pre-treatment of substrates for biogas production

Bochmann G, Montgomery L. Storage and pre-treatment of substrates for biogas production. The biogas handbook. ISBN 978 0 85709 498 8 2013:85-103.

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Biogas substrates are typically moist, which can make them difficult to store because bacteria and mould can grow on them. Ensiling, which involves the production of acid by lactic acid bacteria, is often used to preserve crops cheaply. Biogas substrates are also often fibrous, which can make them difficult to mix and means that some of their energy is locked up within the fibres. Different pre-treatment technologies are being investigated to access the energy in these fibres, to increase the rate of biogas production and to improve the mixing qualities of the substrates. Pre-treatment technologies are based on three principles: physical (including mechanical shear, heat, pressure and electric fields), chemical (acids, bases and solvents) and biological (microbial and enzymatic). Combinations of these principles are also used, including steam explosion, extrusion and thermo-chemical processes. Although many of these processes have been investigated at small scale, few have been analysed at large scale in un-biased studies. Many of these techniques are associated with high energy input (e.g. mechanical and heat pre-treatment), high equipment costs (e.g. mechanical systems where the blades erode) or use large volumes of chemicals (e.g. alkali pre-treatment). Different pre-treatment technologies work better with different substrates, and more research is required in this field to understand which combinations are worthwhile. This chapter describes some of the common pre-treatment technologies along with some advantages and disadvantages.


Conference contributions | 2012

Strategic Research Priorities for Biomass Technology

Haslinger W. Strategic Research Priorities for Biomass Technology, 4th Annual Meeting of the RHC-platform biomass panel 2012, 10th of October 2012, Berlin, Germany.

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Contributions to trade journals | 2014

Strategy for the application of novel characterization methods for biomass fuels: Case study of straw

Obernberger I. Strategy for the application of novel characterization methods for biomass fuels: Case study of straw. Energy and Fuels. 2014;28(2):1041-52.

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Because of an increasing interest in the utilization of new and in terms of combustion-related properties rather unknown biomass fuels in heat and power production, advanced fuel characterization tools are gaining rising interest. Currently, ongoing research and development (R&D) focuses on a better and more precise description of the combustion properties of specific biomass fuels by applying new/advanced analysis methods and modeling tools. These novel characterization methods cover combustion tests in specially designed lab reactors, special fuel indices for biomass fuels, and the dedicated application of high-temperature equilibrium calculations. In this paper, a strategy is presented how the information gained from different advanced fuel characterization methods can be combined to characterize a fuel regarding its combustion behavior in a novel way. By means of this strategy, relevant qualitative and quantitative information regarding the ash-melting behavior, aerosol, SOx, HCl, and NOx emissions to be expected, and high-temperature corrosion risks can be gained. In addition, the approach can also be used for the evaluation of additives and fuel blending as measures to improve specific combustion properties. The results show that a much better and clearer picture about the combustion properties of a specific biomass fuel can be provided than by conventional approaches (such as wet chemical analysis or other standardized methods). The results can be used for the preliminary design of plants as well as for evaluation of the applicability of a specific technology for a certain biomass fuel or fuel spectrum. Moreover, they can be applied in combination with computational fluid dynamics (CFD) simulations for the detailed design and evaluation of furnaces and boilers. © 2014 American Chemical Society.


Conference contributions | 2008

Straw pellets combustion in small-scale boilers. Part 1: Emissions and emission reduction with a novel heat exchanger technology.

Wopienka E, Schwabl M, Emhofer W, Friedl G, Haslinger W, Wörgetter M, Merkl R, Weissinger A. Straw pellets combustion in small-scale boilers. Part 1: Emissions and emission reduction with a novel heat exchanger technology, 16th European Biomass Conference 2008, 2nd-6th of June 2008, Valencia, Spain. p 1386-1392.

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Conference contributions | 2008

Straw pellets combustion in small-scale boilers. Part 2: Corrosion and material optimization.

Emhofer W, Wopienka E, Schwabl M, Friedl G. Straw pellets combustion in small-scale boilers. Part 2: Corrosion and material optimization, 16th European Biomass Conference 2008, 2nd-6th of June 2008, Valencia, Spain. p1500-1503.

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This paper presents one part of the results of a project dealing with straw pellets combustion in small
scale combustion systems. Whereas the other part of the work investigates gaseous and particulate emissions, this part focuses on the results of experiments to determine corrosion of refractory material. Three different types of straw
pellets are combusted in a prototype of a 15 kW residential heating boiler. The fuel samples are natural wheat straw,
wheat straw with alumina based additive and wheat straw with a mixture of calcium-/magnesium carbonate based
additive. Combustion experiments are performed under different operating conditions of the test boiler. Three
different types of refractory material are used as combustion chamber material. The refractory materials are different
mixtures of alumina, silica, zirconia and silicium-carbide. The degree of deterioration of these materials is
investigated for temperatures between 700 and 1300 deg C in the presence of slag formed during combustion of the
straw samples and the influence of the fuel additives on corrosion effects is analysed.


Conference contributions | 2013

Suitable gasification methods and gas cleaning schemes for BtL application of producer gas

Rauch, R. New processes for fuel conversion, gas cleaning and CO2 separation in FB and EF gasification of coal, biomass and waste, Workshop ” Suitable gasification methods and gas cleaning schemes for BtL application of producer gas” (held during the First International Workshop on New processes for fuel conversion, gas cleaning and CO2 separation in FB and EF gasification of coal, biomass and waste) 12th-14th of June, Prague, Czech, 2013.

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Other Presentations | 2015

Survey of modern pellet boilers in Austria and Germany - System design and customer satisfaction of residential installations

Büchner D, Schraube C, Carlon E, von Sonntag J, Schwarz M, Verma VK, Ortwein A. Survey of modern pellet boilers in Austria and Germany - System design and customer satisfaction of residential installations. Applied Energy;160: 390-403.

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The variety of available technical building equipment leads to increasingly complex heating systems with various requirements for efficient operation. Furthermore, in existing buildings the heating system is often historically evolved and contains parts having different ages. Those systems have limited capacity to suit the requirements of replaced components. This paper investigates the operational behavior of small-scale pellet heating systems in Austria and Germany, considering installations in new buildings and boiler replacements in existing buildings and how they are influencing the customer satisfaction.

This investigation was carried out by means of a comprehensive survey for residential customers using pellet fired heating systems. More than 2500 questionnaires were distributed between 2011 and 2013 in Austria, Germany, Greece, Spain and the United Kingdom. In total 293 returned questionnaires were evaluated. The efficiency of the monitored heating systems was estimated using surveyed boiler parameters. Successively, the influence of different operational parameters on the boilers efficiency was evaluated with a statistical analysis, using Pearson correlation coefficient and Spearman correlation.

Results showed that the correct installation of the monitored pellet heating system is easier for new buildings compared to the replacement of old fossil boilers in existing buildings. Optimal operating conditions are characterized by less frequent ignitions and by higher operational loads. Pellet systems operated with a high efficiency in both building types, but for new buildings it is more likely to occur. More than 87% of the participating customers stated that they are highly satisfied with their pellet boiler.


Conference contributions | 2014

Synergies of Wastewater and Microalgae Cultivation

Sonnleitner A, Bacovsky D, Bochmann G, Drosg B, Schagerl M. Synergies of Wastewater and Microalgae Cultivation, Word Sustainable Energy Days next 2014, 26th-28th of February 2014, Wels, Austria.

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Current international research results identify microalgae as a new and promising feedstock for the global energy supply chain. A novel concept to reduce costs and cover the need of water and nutrients is the combination of wastewater treatment and microalgae cultivation. In Austria in particular brewery and dairy effluents as well as municipal wastewater would be suitable for algae cultivation. Cultivation systems practical for the use of wastewater are High Rate Algal Ponds (open system, suspended culture), Algal Turf Scrubbers (open system, immobilized culture) and Photobioreactors (closed systems, suspended culture). The cultivation of microalgae in general and the special case of wastewater as nutrient source face a variety of challenges either concerning the accumulation of microalgal cells in wastewater (upstream process) or their removal and processing (downstream process). Taking a look at the whole production chain shows that for effluents of breweries, dairies
and smale-scale municipal wastewater no feasible concept for the combination of microalgae cultivation and wastewater treatment can be designed. A promising production concept for large-scale municipal wastewater treatment plants are HRAPs or biofilm production in ATS systems for energetic and material pathways. Various R&D challenges are to overcome to lead to an optimization and further development of technologies for combined wastewater treatment and microalgae cultivation in Austria.


Conference contributions | 2013

Synthetic biofuels – do they have a future?

Rauch R. Synthetic biofuels – do they have a future? 8th A3PS Conference Eco-Mobility 2013, 4th of October 2013, Vienna, Austria.

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Conference contributions | 2012

System performance of a storage integrated pellet boiler

Aigenbauer S, Hartl M, Malenkovic I, Simetzberger A, Vverma VK, Schmidl C. System performance of a storage integrated pellet boiler, 20th European Biomass Conference 2012, 18th-22nd of June 2012, Milano, Italy. p 1320-1324.

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A pellet burner directly integrated into the solar storage provides heat and domestic hot water for small
residential applications in an environment-friendly way. The objective of this work was to evaluate the system
performance of a storage integrated pellet boiler in laboratory under transient test conditions. Furthermore, the type
test results according to ÖNORM EN 303-5 [1] of the last decade were compared with monitoring data of systems
with separated boiler and heat storage. The laboratory tests allowed finding relevant parameters and losses, which
influence the system performance. A developed computer simulation model shows the potential to optimize the
performance of the investigated boiler.


Scientific Journals | 2018

Tackling ammonia inhibition for efficient biogas production from chicken manure: Status and technical trends in Europe and China

Fuchs W, Wang X, Gabauer W, Ortner M, Li Z. Tackling ammonia inhibition for efficient biogas production from chicken manure: Status and technical trends in Europe and China (Review). Renewable and Sustainable Energy Reviews 2018;97:186-199.

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The increased global consumption of chicken products has resulted in the generation of huge amounts of manure. Numerous studies emphasized the large potential of this waste as an untapped source of renewable energy through anaerobic digestion (AD). However, intrinsic difficulties, in particular the high N content, induce instable process conditions, including the accumulation of intermediates, and foaming, which reduces methane yields. Such issues limit the widespread application of this energy-rich substrate for biogas production. The process inhibition by ammonia is usually prevented by reducing the concentration of chicken manure through dilution or by operating the plant considerably below its theoretical reactor capacity. However, this process compromises process efficiency, thereby increasing capital investments and operational costs. Another option to achieve optimal process performance is co-digestion with less N-rich materials. However, co-digestion also has its limitations due to the frequent unavailability of sufficient amounts of C-rich substrates. A series of promising technical solutions have been developed to overcome the aforementioned bottlenecks. Examples include stripping or membrane extraction as means to reduce ammonia concentration in the fermenter. Several full-scale plants employing ammonia removal techniques have been installed recently. Latest research also investigated the use of additives, such as zeolites and trace elements, as well as bioaugmentation, to mitigate ammonia inhibition. The current study reviews the state of technology as well as recent achievements and perspectives. It provides an overview of the different approaches to remove ammonia from AD-process and presents practical examples from China and Europe.


Conference contributions | 2010

Tapping the energy contained in waste for renewable energy provision - example of Austria

Ragossnig A. Tapping the energy contained in waste for renewable energy provision - example of Austria, International Work-Shop ENERGY & FUELS FROM WASTE & BIOMASS 2010, 5th of January 2010, Pucon, Chile.

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Conference contributions | 2009

Tar Content and Composition in Producer Gas of Fluidized Bed Gasification and Low Temperature Pyrolysis of Straw and Wood – Influence of Temperature

Aigner I, Wolfesberger U, Hofbauer H. Tar Content and Composition in Producer Gas of Fluidized Bed Gasification and Low Temperature Pyrolysis of Straw and Wood – Influence of Temperature, ICPS 2009, 1st-3rd of September 2009, Vienna, Austria.

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The global warming, the increasing CO2 emission, the combustion of and dependency on fossil
fuels, as well as the high-energy price have resulted in an increasing demand in renewable energy
sources. Biomass, as a renewable energy source, has the potential to contribute to the future energy
mix in various ways. In thermo-chemical biomass conversion processes, especially gasification and pyrolysis, the tar content and its composition is a major subject. Due to the various processes examined at VUT, this
work picks up the opportunity to compare the different tar amounts and compositions at different
temperatures and process parameters. The tar content and composition in the producer gas of steam
gasification of straw and wood as well as the tar yields of low temperature pyrolysis of straw are
displayed in the following work. Gasification experiments were carried out in a 100 kW dual fluidized bed steam gasifier at a temperature range of 700° C to 870° C. Pyrolysis experiments were conducted in a rotary kiln
reactor at temperatures between 600° C and 630° C. For better understanding of tar formation during thermo-chemical conversion of biomass the tar content and composition in the producer gas was analyzed with a gas chromatograph coupled with a mass spectrometer. Main observation was that at higher temperatures the tar composition is shifted to higher molecular tars as poly aromatic hydrocarbons (PAH). Key tar components at lower temperatures (pyrolysis) are phenols. These results give the opportunity to analyse tar formation in different thermochemical conversion steps, therefore, for the future a better understanding of tar formation in large scale facility’s should be gained. This means lower tar content in the producer gas for gasification processes and an achievement of required pyrolysis oil yields for pyrolysis.


Contributions to trade journals | 2009

Tar content and composition in producer gas of fluidized bed gasification of wood - influence of temperature and pressure

Wolfesberger U, Aigner I, Hofbauer H. Tar content and composition in producer gas of fluidized bed gasification of wood-influence of temperature and pressure. Environmental Progress and Sustainable Energy. 2009;28(3):372-9.

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Peer Reviewed Scientific Journals | 2017

Techno-economic assessment of hydrogen production based on dual fluidized bed biomass steam gasification, biogas steam reforming, and alkaline water electrolysis processes

Yao J, Kraussler M, Benedikt F, Hofbauer H. Techno-economic assessment of hydrogen production based on dual fluidized bed biomass steam gasification, biogas steam reforming, and alkaline water electrolysis processes. Energy Conversion and Management. 1 August 2017;145: 278-292.

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Conference contributions | 2020

Techno-economic modelling of bioeconomy value chains

Fuhrmann Marilene

Fuhrmann M. Techno-economic modelling of bioeconomy value chains. 6th Central European Biomass Conference. 2020. Graz.

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Peer Reviewed Scientific Journals | 2014

Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers

Hebenstreit B, Schnetzinger R, Ohnmacht R, Höftberger E, Lundgren J, Haslinger W, et al. Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers. Biomass Bioenergy. 2014;71:12-22.

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An active condensation system for the heat recovery of biomass boilers is evaluated. The active condensation system utilizes the flue gas enthalpy exiting the boiler by combining a quench and a compression heat pump. The system is modelled by mass and energy balances. This study evaluates the operating costs, primary energy efficiency and greenhouse gas emissions on an Austrian data basis for four test cases. Two pellet boilers (10kW and 100kW) and two wood chip boilers (100kW and 10MW) are considered. The economic analysis shows a decrease in operating costs between 2% and 13%. Meanwhile the primary energy efficiency is increased by 3-21%. The greenhouse gas emissions in CO2 equivalents are calculated to 15.3-27.9kg MWh-1 based on an Austrian electricity mix. The payback time is evaluated on a net present value (NPV) method, showing a payback time of 2-12 years for the 10MW wood chip test case. © 2014 Elsevier Ltd.


Technical Reports | 2016

Technology Overview

Strasser C. Technology Overview. New York State Wood Heat Report: An Energy, Environmental, and Market Assessment - Final Report. April 2016. Chapter 8; 141-206.

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Conference contributions | 2012

The actual need of a guideline for sampling and analysis of chemical matter (not tars) from product gas, pyrolysis gas and synthesis gas

Zeisler J, Kleinhappl M, Martini S, Neubauer Y. The actual need of a guideline for sampling and analysis of chemical matter (not tars) from product gas, pyrolysis gas and synthesis gas, 20th European Biomass Conference 2012, 18th-22nd of June 2012, Milano, Italy. p 919-925.

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Due to the increasing number of different online and offline methods and procedures for sampling at gasification and pyrolysis plants a comparison of the measured values is difficult. About the sampling of tars already a number of detailed guidelines and a common approach are established [2]. In terms of discrete chemical impurities the missing of a guideline for sampling at biomass¬ plants is an obstacle for implementing sampling systems in new plants or experimental assemblies. Nevertheless the knowledge is available at several institutions but it has to be collected. Within this paper the basic challenges of sampling are mentioned, the system at Bioenergy2020+ is explained in detail and about the parameters NH3, H2S & HCN useful results of optimisation are reported. This status should help to point out the need of a reliable library of methods. According the first systematisation of offline and online sampling respectively detection a table of application is proposed. The detailed knowledge for this will be treated and exchanged within an established working group which should lead to a guideline (at least methods library) for sampling of trace components as described.


Peer Reviewed Scientific Journals | 2015

The behavior of biomass and char particles in a dual fluidized bed gasification system

Kraft S, Kuba M, Hofbauer H. The behavior of biomass and char particles in a dual fluidized bed gasification system. Powder Technology 2018;338:887-897.

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Biomass gasification in fluidized beds is a complex process in which particles occur in a wide range of size and density. In this paper, the mixing behavior of the char, biomass and bed material in a gasification reactor of a typical dual fluidized bed (DFB) system was investigated in a cold flow model. Experiments with ternary mixtures were performed in which the size and the density of the used particles were varied. For the experiments, a cold flow model was constructed with a full bed material recirculation loop, similar to DFB systems. Experiments revealed that at low fluidization velocities, the smaller char particles and biomass particles occur more preferentially in the bed material recirculation stream. If the fluidization velocities are increased, this tendency diminishes. Furthermore, the experiments showed that the mass fraction of biomass particles in the recirculation stream is always higher than that of the lighter char particles. It is also shown that the current design of the gasification reactor in DFB systems is not optimal. A way to overcome this issue in existing plants is presented.

Contributions to trade journals | 2014

The Biomass Technology Roadmap of the RHC-Platform: Priorities for high efficient large-scale CHP units

Grammelis P, Goodwin N, Alakangas E, Haslinger W, Karampinis E. The Biomass Technology Roadmap of the RHC-Platform: Priorities for high efficient large-scale CHP units. VGB PowerTech. 2014;6:74-79.

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Die europäische Technologie-Plattform für Heizen und Kühlen mit erneuerbaren Energien (RHC-Plattform, www.rhc-platform.org) fördert die Forschung und Entwicklung bei der Wärme- und Kälteproduktion aus erneuerbaren Energiequellen in der EU. Die verschiedenen Endanwendungen (Strom und/oder Bereitstellung von Wärme, Kraftstoff) setzen eine Verdoppelung der Biomassenutzung voraus, um die 20-20-20-Ziele der EU zu erreichen. Neue Ressourcen müssen erschlossen, mobilisiert und der Wirkungsgrad der Umwandlungsprozesse gesteigert werden. In Biomasse-Heizkraftwerken sowie Heizwerken werden derzeit mehr als ein Drittel des gesamten Biomasseaufkommens eingesetzt. Dies führt zu neuen, gemeinsamen Herausforderungen für den Strom- und Wärmesektor.
Das Biomasse-Panel der RHC-Plattform hat Schwerpunkte für Forschung und Entwicklung definiert, um bestimmte Kennzahlen für Biomassewertschöpfungsketten zu erreichen. Der vorliegende Beitrag stellt die Prioritäten für die Bestandteile der Wertschöpfungsketten vor, die relevant für den Strombereich sind:
a) nachhaltige und kosten-effiziente Biomasseversorgungsketten, b) thermisch behandelte Biomasse-Brennstoffe und c) hoch-effiziente KWK-Anlagen.
Herausforderungen für den Anlagenbetrieb sind Brennstoffflexibilität, Wirkungsgraderhöhung über den vollen Lastbereich, Betrieb mit variablen Brennstoffen und Qualitäten bei variablen Lastzuständen, höhere Betriebsparameter für Dampf und andere Wärmeträger, höhere Anlagenverfügbarkeit, Reduktion von unerwünschten gas- und partikelförmigen Emissionen und schließlich die Ascheverwertung.
 


Peer Reviewed Scientific Journals | 2020

The effect of the reaction equilibrium on the kinetics of gas-solid reactions — A non-parametric modeling study.

Birkelbach F, Deutsch M, Werner A. The effect of the reaction equilibrium on the kinetics of gas-solid reactions — A non-parametric modeling study. Renewable Energy 2020.152:300-307.

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The viability of thermochemical energy storage for a given application is often determined by the reaction kinetics under process conditions. For high exergetic efficiency the process needs to operate in close proximity to the reaction equilibrium. Thus, accurate kinetic models that include the effect of the reaction equilibrium are required.

In the present work, different parametrization methods for the equilibrium term in the General Kinetic Equation are evaluated by modeling the kinetics of two reaction systems relevant for thermochemical energy storage (CaC2O4 and CuO) from experimental data. A non-parametric modeling method based on tensor decompositions is used that allows for a purely data driven assessment of different parametrization methods.

Our analysis shows that including a suitable equilibrium term is crucial. Omitting the equilibrium term when modeling formation reactions can lead to seemingly negative activation energies. Our tests also show that for formation reactions, the reaction rate decreases much faster towards the equilibrium than theory predicts. We present an empirical modeling approach that can predict the reaction rate of gas-solid reactions, regardless of the shortcomings of theory. In this way, non-parametric modeling offers a powerful tool for applied research and may contribute to the advancement of the thermochemical energy storage technology.


Technical Reports | 2018

The Green P - Nutzung von städtischen Verkehrsflächen für die Produktion von Biomasse

Lichtenegger K, Meixner K, Riepl R, Schipfer F, Zellinger M. The Green P - Nutzung von städtischen Verkehrsflächen für die Produktion von Biomasse. BMVIT, Schriftenreihe 25/2018.

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