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Conference contributions | 2014

Towards a Stochastic Cellular Automata Model of Log Wood Combustion

Lichtenegger K, Schappacher W, Hebenstreit B, Schmidl C, Höftberger E. Towards a Stochastic Cellular Automata Model of Log Wood Combustion. Journal of Physics: Conference Series. 2014:490:102015. (peer reviewed)

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Describing the combustion of log wood and others solid fuels with complex geometry, considerable water content and often heterogenous struture is a nontrivial task. Stochastic Cellular Automata models offer a promising approach for modelling such processes. Combustion models of this type exhibit several similarities to the well-known forest fire models, but there are also significant differences between those two types of models. These differences call for a detailed analysis and the development of supplementary modeling approaches. In this
article we define a qualitative two-dimensional model of burning log wood, discuss the most important differences to classical forest fire models and present some preliminary results.


Conference contributions | 2014

Transport Biofuels in Europe - A Vision for 2030

Wörgetter M. Transport Biofuels in Europe - A Vision for 2030, Fuels of the Future 2014, 20th-21st of January 2014, Berlin, Germany.

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Contributions to trade journals | 2014

Wood Gas Processing To Generate Pure Hydrogen Suitable for PEM Fuel Cells

Fail S, Diaz N, Benedikt F, Kraussler M, Hinteregger J, Bosch K, et al. Wood gas processing to generate pure hydrogen suitable for PEM fuel cells. ACS Sustainable Chemistry and Engineering. 2014;2(12):2690-8.

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A test campaign was carried out to generate renewable hydrogen based on wood gas derived from the commercial biomass steam gasification plant in Oberwart, Austria. The implemented process consisted of four operation units: (I) catalyzed water-gas shift (WGS) reaction, (II) gas drying and cleaning in a wet scrubber, (III) hydrogen purification by pressure swing adsorption, and (IV) use of the generated biohydrogen (BioH2) in a proton exchange membrane (PEM) fuel cell. For almost 250 h, a reliable and continuous operation was achieved. A total of 560 (Ln dry basis (db))/h of wood gas were extracted to produce 280 (Ln db)/h of BioH2 with a purity of 99.97 vol %db. The catalyzed WGS reaction enabled a hydrogen recovery of 128% (nBioH2)/(nH2,wood gas) over the whole process chain. An extensive chemical analysis of the main gas components and trace components (sulfur, CxHy, and ammonia) was carried out. No PEM fuel cell poisons were measured in the generated BioH2. The only detectable impurities in the product were 0.02 vol %db of O2 and 0.01 vol %db of N2. © 2014 American Chemical Society.


Contributions to trade journals | 2013

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

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

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


Contributions to trade journals | 2013

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

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

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


Conference contributions | 2013

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

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

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Conference contributions | 2013

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

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

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Other Presentations | 2013

Analyse und Optimierung der Verfügbarkeit vom BHKW Güssing

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

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Conference contributions | 2013

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

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

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Contributions to trade journals | 2013

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

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

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


Conference contributions | 2013

AshMelT – Development of a Practical and Reliable Ash Melting Test for Biomass Fuels, in particular for Wood Pellets

Feldmeier S, Schwabl M, Höftberger E, Wopienka E. AshMelT – Development of a Practical and Reliable Ash Melting Test for Biomass Fuels, in particular for Wood Pellets, European Pellets Conference 2013, 27th-28th of February 2013, Wels, Austria.

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Contributions to trade journals | 2013

Assessment of online corrosion measurements in combination with fuel analysis, aerosol and deposit measurements in a biomass CHP plant

Retschitzegger S, Brunner T, Waldmann B, Obernberger I. Assessment of online corrosion measurements in combination with fuel analysis, aerosol and deposit measurements in a biomass CHP plant. Energy and Fuels. 2013;27(10):5670-5683.

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To systematically investigate high-temperature corrosion of superheaters in biomass combined heat and power
(CHP) plants, a long-term test run (5 months) with online corrosion probes was performed in an Austrian CHP plant (28 MWNCV; steam parameters: 32 t/h at 480 °C and 63 bar) firing chemically untreated wood chips. Two corrosion probes were applied in parallel in the radiative section of the boiler at average flue gas temperatures of 880 and 780 °C using the steel 13CrMo4-5 for the measurements. Corrosion rates were determined for surface temperatures between 400 and 560 °C. The results show generally moderate corrosion rates and a clear dependence upon the flue gas temperatures and the surface temperatures of the corrosion probes, but no influence of the flue gas velocity has been observed. The data are to be used to create corrosion diagrams to determine maximum steam temperatures for superheaters in future plants, which are justifiable regarding the corrosion rate. Dedicated measurements were performed at the plant during the long-term corrosion probe test run to gain insight into the chemical environment of the corrosion probes. From fuel analyses, the molar 2S/Cl ratio was calculated with an average of 6.0, which indicates a low risk for high-temperature corrosion. Chemical analyses of aerosols sampled at the positions of the corrosion probes showed that no chlorine is present in condensed form at the positions investigated. Deposit probe measurements performed at the same positions and analyses of the deposits also showed only small amounts of chlorine in the deposits, mainly found at the leeward position of the probes. Subsequent to the test run, the corrosion probes have been investigated by means of scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses. The results confirmed the deposit probe measurements and showed only minor Cl concentrations in the deposits and no Cl at the corrosion front. Because, in the case of Cl-catalyzed active oxidation, a layer of Cl is known to be found at the corrosion front, this mechanism is assumed to be not of relevance in the case at hand. Instead, elevated S concentrations were detected at the corrosion front, but the corrosion mechanism has not yet been clarified.


Other Presentations | 2013

Ausbrandregelung von Biomasse-Kleinfeuerungsanlagen

Rumpf, M. Ausbrandregelung von Biomasse-Kleinfeuerungsanlagen, Master Thesis, Technische Universität Graz, Graz, Austria, 2013.

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 Die Anzahl der installierten Biomasse-Kleinfeuerungsanlagen ist in letzter Zeit deutlich gestiegen. Aus diesem Grund ist es umso wichtiger eine schadstoffarme und effiziente Verbrennung zu ermöglichen. Genau diese Anforderung stellt jedoch eine große Herausforderung für deren Regelung dar. Der optimale Restsauerstoffgehalt des Rauchgases, im Sinne von niedrigen Kohlenmonoxidemissionen (CO-Emissionen) bei bestmöglichem Wirkungsgrad, ist sehr stark vom Betriebszustand, von der Anlagengeometrie und vom verwendeten Brennstoff abhängig. Diese Tatsache wird jedoch derzeit bei den Regelungen von Biomasse-Kleinfeuerungsanlagen nicht oder nur teilweise berücksichtigt. Um hohe CO-Emissionen aufgrund von Sauerstoffmangel in jedem Fall zu vermeiden, werden Biomasse-Kleinfeuerungsanlagen üblicherweise mit vergleichsweise hohem Sauerstoff betrieben. Diese Maßnahme geht jedoch mit einer unerwünschten Reduktion des Wirkungsgrades der Feuerung einher. Diese Arbeit hat zum Ziel eine Strategie zu entwickeln, welche das Luftverhältnis sowie auch die Luftstufung während des Betriebes dahingehend anpasst, dass stets ein möglichst effizienter und dennoch schadstoffarmer Betrieb gewährleistet wird. Die im Rahmen dieser Masterarbeit behandelten Arbeiten, wurden anhand einer handelsüblichen Biomasse-Kleinfeuerungsanlage durchgeführt. Die verwendete Anlage wird mit Hackgut betrieben und hat eine Kesselnennleistung von 30 kW. Für die Anwendung einer Strategie zur Reduktion der CO-Emissionen wäre es von großem Vorteil, wenn der CO-Gehalt des Rauchgases gemessen werden könnte. Derzeit gibt es jedoch nur sehr teure Rauchgasanalyseeinheiten, welche für eine dauerhafte Bestimmung des CO-Gehaltes des Rauchgases geeignet sind. Somit war bis jetzt eine Messung des CO-Gehalts nur bei großen Biomassefeuerungsanlagen wirtschaftlich. In dieser Arbeit wurde zunächst eine Marktanalyse zu preiswerten Sensoren zur Detektion unverbrannter Komponenten im Rauchgas durchgeführt. Es wurden ausschließlich Sensoren untersucht, die aufgrund ihres geringen Preises auch wirtschaftlich eingesetzt werden können. Dabei zeigte sich, dass es derzeit zwei Sensoren gibt, welche diese Anforderungen erfüllen. Diese Sensoren dienen jedoch lediglich zur Detektion von unverbrannten Komponenten im Rauchgas und sind nicht in der Lage den CO-Gehalt des Rauchgases exakt zu messen. Aus diesem Grund wurde der Zusammenhang zwischen CO-Konzentration und Sensorsignal untersucht und anschließend mathematisch beschrieben, wobei die wesentlichen Querempfindlichkeiten berücksichtigt wurden. Da die physikalischen Zusammenhänge sehr komplex und zu einem wesentlichen Teil nicht bekannt waren, wurde das mathematische Modell mit Hilfe der experimentellen Modellbildung ermittelt, wobei die verwendeten Messdaten einen möglichst großen Bereich der verschiedenen Einflussparameter beinhalteten. In weiterer Folge wurden umfassende Testläufe zur Untersuchung der Auswirkung der Leistung, des Luftverhältnisses im Brennstoffbett, des gesamten Luftverhältnisses und des Brennstoffwassergehaltes auf die CO-Emissionen durchgeführt. Die Ergebnisse zeigten, dass es für einen möglichst effizienten und gleichzeitig schadstoffarmen Betrieb notwendig ist, das Luftverhältnis im Brennstoffbett sowie den Sekundär"-luft"-massen"-strom in Abhängigkeit der geforderten Leistung zu variieren. Darauf aufbauend wurde eine geeignete Strategie zur Umsetzung dieser Maßnahmen entwickelt und implementiert. Dabei werden die Führungsgrößen für den Restsauerstoffgehalt sowie das Luftverhältnis im Brennstoffbett laufend an die geforderte Leistung angepasst. Zusätzlich dazu wird die Führungsgröße für den Restsauerstoffgehalt durch einen Suchalgorithmus zur Minimierung der CO-Emissionen variiert. Schlussendlich wurde die entwickelte Strategie mit Hilfe eines typischen Lastzyklus experimentell verifiziert. 


Other Presentations | 2013

Austrian context for biowaste and case study on brewery waste

Bochmann G. Austrian context for biowaste and case study on brewery waste, Biogaz Europe 2013, 20th of March 2013, Nantes, France.

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Other Presentations | 2013

Automatisierung und Visualisierung einer Anlage zur Wasserstoffgewinnung aus Biomasse

Malits, M. Automatisierung und Visualisierung einer Anlage zur Wasserstoffgewinnung aus Biomasse, Master Thesis, Fachhochschule Technikum Wien, Vienna, Austria, 2013.

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Contributions to trade journals | 2013

Behavior of inorganic matter in a dual fluidized steam gasification plant

Kirnbauer F, Koch M, Koch R, Aichernig C, Hofbauer H. Behavior of inorganic matter in a dual fluidized steam gasification plant. Energy and Fuels. 2013;27(6):3316-31.

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Ash components of biomass fuels can cause fouling, slagging, and bed material agglomeration during thermal utilization in fluidized bed combustion and gasification plants. The influence of ash components on these problems in dual fluidized bed biomass gasification plants is investigated in an industrial scale plant in Güssing, Austria. Samples of fouling are analyzed, and the results are evaluated. The samples were analyzed by X-ray fluorescence analysis and thermal analyses such as thermogravimetric analysis, differential thermal analysis, and differential scanning calorimetry. Mass balances of inorganic matter are presented, evaluating different loop configurations. The analyses showed high potassium contents compared to the fuel ash composition in fouling of up to 23% by weight. The potassium content of fly ash with a particle size smaller than 200 μm is half that of coarse fly ash with a particle size larger than 200 μm. The thermal analyses showed a large difference between samples of inorganic streams such as fly ash or fly char and fouling. Different fractions of fly ash samples (particle fraction smaller than 200 μm and particle fraction larger than 200 μm) showed similar thermal behavior: endothermic weight losses at around 400 C and around 720-820 C caused by decomposition of carbonates. The composition of inorganic matters of fly ash and fly char is similar. The elemental composition of deposits at the cyclone wall and the first heat exchanger in the flue gas path showed high potassium contents up to 23.6%. While samples of fly ash and fly char did not show significant melting in their thermal behavior, melting could be detected with fouling at temperatures higher than 1000 C. Mass balances of inorganic matter showed a flow of potassium oxide from the combustion reactor to the gasification reactor, which leads to unexpected high potassium concentrations in the fly char. A reduction of ash loops reduces the amount of potassium that is transferred from the combustion reactor to the gasification reactor. Recommendations are made for the operation of dual fluidized bed gasification plants in terms of ash handling to reduce tendencies for fouling, slagging, and bed material agglomeration. © 2013 American Chemical Society.


Conference contributions | 2013

Bioenergie aus Mikroalgen - Forschung und Vernetzung im Kompetenzzentrum BIOENERGY 2020+

Sonnleitner A. Vernetzungsworkshop "Algen als biogene Ressource - Akteure in Österreich", Bioenergie aus Mikroalgen - Forschung und Vernetzung im Kompetenzzentrum BIOENERGY 2020+, 6th of November, Wieselburg-Land, Austria, 2013.

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Conference contributions | 2013

Bioenergielösungen im Neubau

Schmidl C, Moser W, Reichert G. Bioenergielösungen im Neubau, Veranstaltung des Biomasseverbandes "Erneuerbare Wärme-Schlüssel zur Energiewende" 2013, 8th of May 2013, Vienna, Austria.

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Conference contributions | 2013

Bioenergy and Microalgae - Research and networking activities at the Austrian competence centre BIOENERGY 2020+ with a special focus on Algae energy

Sonnleitner A, Bacovsky D, Wörgetter M. J –EraCenter, Workshop “Bioenergy and Microalgae - Research and networking activities at the Austrian competence centre BIOENERGY 2020+ with a special focus on Algae energy”, 21st of November, Vienna, Austria, 2013.

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Conference contributions | 2013

Biofuels in Austria – yesterday, today and tomorrow

Wörgetter M, Bacovsky D. Biofuels in Austria – yesterday, today and tomorrow, 20th International Symposium on Alcohol Fuels (ISAF) 2013, 25th-27th of March 2013, Cape Town, South Africa.

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Conference contributions | 2013

Biofuels RD&D in BIOENERGY 2020+

Bacovsky D. Biofuels RD&D in BIOENERGY 2020+, Eco-Mobility Conference 2013, 3rd-4th of October 2013, Vienna, Austria.

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Conference contributions | 2013

Biomass Price Volatility - Analysis of the Historic Biomass and Energy Price volatility in the Austrian Market

Kristöfel C, Strasser C, Morawetz U, Schmidt J, Schmid E. Biomass Price Volatility - Analysis of the Historic Biomass and Energy Price volatility in the Austrian Market, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 1721-1727.

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Several energy and agricultural commodities have experienced higher price volatility in recent years. Hence, the interest in food and energy security issues as well as price volatility has increased, particularly since the rise in food and energy commodity prices in 2007/2008. Volatility is associated with risk since higher price volatility leads to additional costs that are often shared and transmitted along the supply chain to the final consumers. Volatility of woody biomass prices is also possibly higher due to increased market dynamics and integration as well as renewable energy policy intervention. We compute historic price volatility using the standard deviation of log returns as well as univariate GARCH models and empirically analyze whether or not price volatility of woody biomass commodities has increased in recent years. We also compare the historic price volatility of woody biomass to the price volatility of agricultural commodities and fossil fuels. Results indicate that the price volatility of some woody biomass commodities has increased, but it is still lower than of agricultural biomass and fossil fuels.


Other Presentations | 2013

Can bioavailability of trace nutrients be measured in an AD process?

Ortner M, Rachbauer L, Somitsch W, Fuchs W. Can bioavailability of trace nutrients be measured in an AD process? Bioenergy Conference 2013, 4th-6th of September 2013, Jyväskylä, Finnland.

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Conference contributions | 2013

Characterisation of Jatropha mahafalensis oil

Sonnleitner A. Characterisation of Jatropha mahafalensis oil, Word Sustainable Energy Days next 2013, 27th-28th of February 2013, Wels, Austria.

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Conference contributions | 2013

Characterization of modern biomass heating and domestic hot water supply systems

Haslinger W, Schmidl C, Schwarz M, Schwabl M, Golicza L, Carlon E, Wopienka E, Verma V. Characterization of modern biomass heating and domestic hot water supply systems, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark.

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