Steam gasification of plastic materials was studied in a dual fluidized bed gasification pilot plant (DFB). Several types of plastics, which are available in large amounts in waste streams, were investigated: PE, PP, and mixtures of PE + PS, PE + PET and PE + PP. It was found that the product gas from PE was rich in CH₄ and C₂H₄ and had a LCV of 25 MJ/N m ³. About 22% of PE was converted to the monomer C₂H₄. Different mixtures of PE with other polymers showed, that the concentrations of CH₄ and C₂H₄increased with an increasing proportion of PE and that they were the main decomposition products of PE. The product gas from pure PP contained more CH₄ and less C₂H₄compared to the product gas from PE. The polymer mixtures behaved differently from the pure substances. Significantly more H₂ and CO were generated from PE + PP and PE + PS. It can be assumed that the decomposition products of the two polymers in the mixture interacted strongly and alternately influenced the gasification process. More water was converted, so the gas production increased. The reforming reactions were enhanced and yielded H₂ and CO at the expense of CH₄ and C₂H₄. The mixture of PE + PET differed from the other polymers because of the high oxygen content of PET. Thus, 28% of CO2 were measured in the product gas. By contrast, CO₂ was in the range of 8%, when oxygen-free polymers were gasified and CO₂ was only produced from reactions with steam. Gasification of polymers resulted in significantly high tar loads in the product gas in the range of 100 g/N m ³. The GCMS analysis of tars showed that tars from polymers mainly consisted of PAH and aro-matics. Naphthalene was the most important tar compound. © 2013 Elsevier Ltd. All rights reserved.

Steam gasification of plastic materials was studied in a dual fluidized bed gasification pilot plant (DFB). Several types of plastics, which are available in large amounts in waste streams, were investigated: PE, PP, and mixtures of PE + PS, PE + PET and PE + PP. It was found that the product gas from PE was rich in CH₄ and C₂H₄ and had a LCV of 25 MJ/N m ³. About 22% of PE was converted to the monomer C₂H⁴. Different mixtures of PE with other polymers showed, that the concentrations of CH₄ and C₂H₄ increased with an increasing proportion of PE and that they were the main decomposition products of PE. The product gas from pure PP contained more CH₄ and less C₂H₄ compared to the product gas from PE. The polymer mixtures behaved differently from the pure substances. Significantly more H₂ and CO were generated from PE + PP and PE + PS. It can be assumed that the decomposition products of the two polymers in the mixture interacted strongly and alternately influenced the gasification process. More water was converted, so the gas production increased. The reforming reactions were enhanced and yielded H₂ and CO at the expense of CH₄ and C₂H₄. The mixture of PE + PET differed from the other polymers because of the high oxygen content of PET. Thus, 28% of CO were measured in the product gas. By contrast, CO₂ was in the range of 8%, when oxygen-free polymers were gasified and CO₂ was only produced from reactions with steam. Gasification of polymers resulted in significantly high tar loads in the product gas in the range of 100 g/N m ³. The GCMS analysis of tars showed that tars from polymers mainly consisted of PAH and aro-matics. Naphthalene was the most important tar compound. © 2013 Elsevier Ltd. All rights reserved.

During storage of wood pellets emissions of carbon monoxide (CO) and a large quantity of volatile organic compounds (VOCs) can be detected. These off-gases have been reported to originate from autooxidation reactions of woods own fatty acids, but data on CO formation rates based on fatty acid content is still scarce. In this paper data on the formation rates of CO from oxidation of pure linoleic acid are presented and compared to CO formation rates measured from spruce shavings, spruce sawdust and pellets made from the respective raw materials. To determine whether linoleic acid content is a realistic prediction tool for CO formation the fatty acid contents of the spruce materials have been determined and a comparison of predicted CO formation rates (based on linoleic acid content) to actually measured CO formation rates has been made. The results show that, albeit the fact that the determination of linoleic acid content is not the sole determining factor for an accurate prediction of CO formation rates, it is a helpful indicator in estimating a critical maximum rate of CO formation. The actual formation rates for CO, however, are typically lower than the predicted values and depend to a large extent on the history of the material and whether or not it has been activated. Activation includes treatments such as pelletizing, drying and/or milling.

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.

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.

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

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.

Der Schwerpunkt dieser Arbeit richtet sich auf die Kondensation von Aschedämpfen und die Feinstaubablagerung in Biomasse-befeuerten Kesseln. Zu diesem Zweck wurden in einer Versuchsanlage aschebildende Substanzen verdampft und anschließend auf einer gekühlten Sonde kondensiert. Als Modellsubstanz für die Aschedämpfe der Biomasse wurde Kaliumchlorid verwendet. Das Rauchgas wurde dabei mittels Verbrennung von Erdgas durch einen Gasbrenner zur Verfügung gestellt. Es sollten Informationen darüber gewonnen werden, welche Struktur die Depositionsschicht durch Kondensation oder Feinstaubablagerung ausbildet (Porosität, Homogenität, Festigkeit, Struktur) und wie die gebildete Depositionsschicht den Wärmeübergang beeinflusst. Die Berechnung des Kondensationsmassenstromes der aschebildenden Substanz mittels eines Ähnlichkeitsansatzes zum Wärmeübergang (Lewis-Ansatz) zeigt eine gute Übereinstimmung zu den experimentellen Versuchen. Die Depositionsschicht weist eine sehr hohe Porosität (p > 0,97) auf. Das Wärmeleitmodell „k maximum“ berechnet entsprechende Werte für die Wärmeleitfähigkeit der Depositionsschicht. Die Struktur der gebildeten Depositionsschicht ist von der Oberflächentemperatur der Sonde abhängig. Bei niedriger Sondentemperatur (T1 = 300 °C) bildet sich das Gefüge der Kondensationsschicht aus Kaliumchlorid als würfelförmige Kristalle aus, die „turmartig“ aufeinander herauswachsen. Diese Schicht zeichnet sich durch eine höhere Stabilität aus. Bei höherer Sondentemperatur (T2 = 500 °C) ist das Gefüge aus kleineren nadeligen und tröpfchenförmigen Kristallen aufgebaut, welche „baumartig“ herauswachsen. Wenn man die Kondensationsschicht am Depositionsring betrachtet wird ersichtlich, dass sich die Verteilung der Depositionsmenge in Abhängigkeit von der Depositionsmasse sehr unterschiedlich ausbildet. Bei geringer Depositionsmenge (m < 0,01 [g]) ist die Verteilung gleichmäßig um den Ring verteilt, bei höherer Depositionsmenge (m>0,01 [g]) befindet sich der Hauptteil der Depositionsmasse hauptsächlich auf der rauchgaszugewandten Seite der Sonde. Obwohl die Berechnung der Kondensationsmassenströme mit Hilfe des Ähnlichkeitsansatzes eine gute Übereinstimmung zeigt, sind die berechneten Werte stets etwas höher als die gemessenen Ergebnisse. Es wird vermutet, dass die Ursache in der hohen Instabilität der Depositionsschicht liegt, wodurch Erosionsvorgänge durch die vom Rauchgas erzeugten Schubspannungen die Depositionsschichtdicke reduzieren. Die Wärmeleitfähigkeit der Depositionsschicht ist aufgrund der hohen Porosität (hoher Anteil des fluiden Rauchgasanteils mit geringer Wärmeleitfähigkeit, kleiner Anteil des stark wärmeleitenden festen Kaliumchlorids) sehr niedrig, aber trotzdem deutlich höher als die Wärmeleitfähigkeit des Rauchgases. Sie liegt in der Größenordnung von k = 0,1-0,2 [W/mK]. Schon geringe Depositionsschichtmassen bewirken eine starke Verringerung des Wärmeüberganges und einen damit verbundenen hohen Temperaturgradienten in der Depositionsschicht. In dieser Arbeit wurden die für den Aufbau der Depositionsschicht maßgebenden Einflussfaktoren untersucht. Diese sind die Rauchgasgeschwindigkeit, die Salzfreisetzung, die Kondensationsdauer und die Oberflächentemperatur. Die Salzfreisetzung ist maßgebend für die Kondensationsmasse. Eine Verdoppelung der Salzfreisetzungsrate zeigte im untersuchten Wandbereich eine Verdoppelung der Kondensationsrate. Eine Verdoppelung der Rauchgasgeschwindigkeit führte zu einer geringen Abnahme der Kondensationsmasse bei gleichbleibenden Betriebsparametern, welches höchstwahrscheinlich durch Erosionsvorgänge bedingt ist. Die Sondenoberflächentemperatur zeigte im untersuchten Temperaturbereich von 300°C-500°C bei geringen Kondensationsmassen keinen Einfluss auf die Kondensationsrate. Bei größeren Depositionsschichten hatte die höhere Temperatur eine Verringerung der Kondensationsrate zur Folge.  

Fischer-Tropsch (FT) synthesis is one option to produce liquid transportation fuels from carbon-containing feedstocks. In the past, FT synthesis was used mainly to convert coal or natural gas to diesel and gasoline. In the last decade, much R&D effort has been made to use this technology to convert biomass to a high-quality transportation fuel. In this chapter, the technology for BtL (conversion of biomass to liquid transportation fuels over FT synthesis) is described, from synthesis gas production including requirements on the gas quality to a detailed description of the FT synthesis itself. The main focus of this chapter is to give an overview of the types of catalysts, also including their preparation, reduction, and aging; the types of FT reactors; and also the reaction conditions including kinetic laws and mechanistic proposals.

Heavy fractions resulting from mechanical treatment stages of mechanical-biological waste treatment plants are posing very specific demands with regard to further treatment (large portions of inert and high-caloric components). Based on the current Austrian legal situation such a waste stream cannot be landfilled and must be thermally treated. The aim of this research was to evaluate if an inert fraction generated from this waste stream with advanced separation technologies, two sensor-based [near-infrared spectroscopy (NIR), X-ray transmission (XRT)] and two mechanical systems (wet and dry) is able to be disposed of. The performance of the treatment options for separation was evaluated by characterizing the resulting product streams with respect to purity and yield. Complementing the technical evaluation of the processing options, an assessment of the economic and global warming effects of the change in waste stream routing was conducted. The separated inert fraction was evaluated with regard to landfilling. The remaining high-caloric product stream was evaluated with regard to thermal utilization. The results show that, in principal, the selected treatment technologies can be used to separate high-caloric from inert components. Limitations were identified with regard to the product qualities achieved, as well as to the economic expedience of the treatment options. One of the sensor-based sorting systems (X-ray) was able to produce the highest amount of disposeable heavy fraction (44.1%), while having the lowest content of organic (2.0% C_biogenic per kg waste input) components. None of the high-caloric product streams complied with the requirements for solid recovered fuels as defined in the Austrian Ordinance on Waste Incineration. The economic evaluation illustrates the highest specific treatment costs for the XRT (€23.15 per t), followed by the NIR-based sorting system (€15.67 per t), and the lowest costs for the air separation system (€10.79 per t). Within the ecological evaluation it can be shown that the results depend strongly on the higher heating value of the high caloric light fraction and on the content of Cbiogenic of the heavy fraction. Therefore, the XRT system had the best results for the overall GWP [-14 kg carbon dioxide equivalents (CO₂eq) per t of input waste] and the NIR-based the worst (193 kg CO₂ eq per t of input waste). It is concluded that three of the treatment options would be suitable under the specific conditions considered here. Of these, sensor-based sorting is preferable owing to its flexibility. © The Author(s) 2013.

An in-bed and an on-bed feeding system are implemented in a dual fluidized bed gasifier in order to investigate the influence of the fuel feeding position on the gasification process. Two bed materials, fresh and used olivine, are used because of their varying catalytic activity. The comparison of in-bed and on-bed feeding of wood pellets shows that in-bed feeding is more favorable, because lower tar concentrations are achieved and the gas composition is closer to water-gas shift equilibrium. Better mixing of bed material and fuel particles occurs with in-bed feeding. The residence time of the gas phase in the fluidized bed is longer in the case of in-bed feeding, and therefore better performance of the gasifier is achieved. Sufficient residence time of the fuel in the bubbling bed is important when a less active bed material is used. More active bed material is capable of compensating for the shorter residence time of the gas phase in contact with bed material during on-bed feeding. •Experimental investigation of in-bed and on-bed feeding.•Two bed materials (catalytic activity) and two fuels (devolatilization behavior).•In-bed feeding more favorable due to lower tar concentration and better gas quality.•Residence time of the gas phase in the fluidized bed is longer during in-bed feeding.•More active bed material compensates for shorter residence time of the gas phase. © 2013 Elsevier Ltd.

The influence of the distribution of fuel particle size on steam gasification was studied systematically in a dual fluidized bed gasifier. Pilot plant gasification experiments have been conducted using sawdust and pellets produced from the same raw material. Three different kinds of waste wood with a broad particle size distribution were also considered for comparison. The fuels differ in their content of particles smaller than 1 mm of equivalent diameter. With an increasing proportion of particles smaller than 1 mm, the product gas contained less H₂ and more CO and CH₄. Less product gas was generated and the concentration of tar increased. It is observed that entrainment of small fuel particles plays an important role in the dual fluidized bed gasifier. Based on the superficial gas velocity in the freeboard of the gasification reactor, a limiting diameter for the entrainment of fuel particles can be determined. Under the conditions investigated a total of 22 wt.% of fuel particles present in the mixture of sawdust and pellets was entrained very rapidly after feeding because of their size. They mainly devolatilize in the freeboard and only have limited contact with the catalytic bed material. Therefore, these volatiles are less likely to be reformed and more tar is found in the product gas. As a conclusion, the particle size determines the region where the thermal conversion of the fuel particle mainly takes place: within the fluidized bed or in the freeboard. © 2013 Elsevier B.V.
 

In order to gain deeper insights into aerosol formation processes during MSW combustion, test runs with a specially developed high-temperature aerosol measurement and sampling device, the so called high-temperature impactor (HTI), as well as subsequent chemical analyses of the particles sampled have been performed at a real-scale plant. The results show that aerosol formation during MSW combustion is based on the volatilisation of minor amounts of Si-, Ca-, Mg- and Al-compounds followed by nucleation in the fuel bed region which is then followed by excessive condensation of alkaline metal sulphates and especially chlorides in the radiative and the convective boiler sections. At lower flue gas temperatures in the superheater as well as the economiser section also the condensation of heavy metal (Zn, Pb) chlorides provides contributions to aerosol formation. © 2011 Elsevier B.V.

Access to affordable and renewable sources of energy is crucial to reducing poverty and enhancing rural development in countries of the global South. Straight vegetable oil was recently identified as a possible alternative to conventional biomass for rural energy supply. In this context, the Jatropha curcas Linn. species has been extensively investigated with regard to its potential as a biofuel feedstock. In contrast, only little is known about Jatropha mahafalensis Jum. & H. Perrier, which is an indigenous and endemic representative of the Jatropha genus in Madagascar. This paper explores the potential and suitability of J. mahafalensis as a biofuel feedstock. Seed samples were collected in the area of Soalara in south-western Madagascar in February and September 2011. Two agro-ecological zones (coastal area and calcareous plateau) and two plant age groups (below and above 10. years) were considered. These four sample groups were analyzed with regard to oil properties, element contents, and fatty acid profiles. Measured values differed greatly between the two harvests, probably owing to different climatic or storage conditions. No direct relation between age of trees or location and oil quality could be established. The analyses indicate that J. mahafalensis oil can be used in oil lamps, cooking stoves and stationary combustion engines for electrification or for biodiesel production. However, modifications in storage and extraction methods, as well as further processing steps are necessary to enable its utilization as a straight vegetable oil and feedstock for biodiesel production. If these technical requirements can be met, and if it turns out that J. mahafalensis oil is economically competitive in comparison with firewood, charcoal, paraffin and petroleum, it can be considered as a promising feedstock for rural energy supply. © 2013 International Energy Initiative.

Operating biomass stoves in modern buildings with tight shells often requires a room-independent air supply. One possibility to arrange this supply is to use a double-wall chimney with fresh air entering through the annular gap. For this setup, a mathematical model has been developed and checked with experimental data. It turned out that for commercially available chimneys, leakage is not negligible and inclusion of leak air in the calculation is crucial for reproduction of the experimental data. Even with inclusion of this effect, discrepancies remain which call for further investigations and a refinement of the model.

The present paper introduces a life cycle modeling approach for representing actual demand of energy or energy intensive products delivered within a system (electricity, heat, etc.) for optimization of the energy mix, according to some of the available life cycle impact assessments (LCIAs). Unlike classical LCA modeling approach, the real amount of several energy products leaving the system and the interactions due to the presence of multi-output processes are considered within the present approach. As a case study, future scenarios are obtained for the Belgian electricity mix production and the heat mix potentially substituted by CHP or biomass, switching between abandoning or not power from nuclear energy. The possibility of using natural gas, biomass for cogeneration, wind power and solar photovoltaic energy are considered within the availability ranges of these resources. Finally, results are presented from successive optimizations according to the sustainability potential defined in a previous paper. A pathway to a more sustainable Belgian energy system is obtained. Finally it is concluded that under the modeling conditions and without nuclear energy it is not possible to obtain a reduction of GHGs and despite diminishing of non-renewable resource consumption, a rising of toxicity is obtained. © 2013 Elsevier Ltd.

Product gas produced by biomass gasification contains small amounts of sulfur compounds (hydrogen sulfide) which can reduce catalyst activity during steam reforming process. Sulfur removal has a negative effect on process efficiency and steam reforming has to be run without cleaning the gas prior to the reactor. It is therefore of interest to investigate the effect of sulfur on the performance of steam reforming reactions. In this work a packed bed reactor filled with nickel based catalysts is mathematically modeled to simulate the steady state pseudo-heterogeneous equations representing heat and mass transfer in the reactor tube. Catalytic bed is subjected to hydrogen sulfide and an isotherm model for the sulfur coverage on the Ni surface is considered to exactly investigate sulfur poisoning effects on methane conversion, hydrogen yield, carbon dioxide and carbon monoxide concentration. It is shown that even when present in the hydrocarbon feedstock in small quantities, (ppm) levels, sulfur can have a significant effect in methane conversion and temperature distribution within the reactor. © 2013 Elsevier B.V.

La combustione di biomassa legnosa con piccoli apparecchi e caldaie è oggi vista con rinnovato interesse per il raggiungimento degli obiettivi comunitari di produzione di energia rinnovabile al 2020. L’aumento dell’utilizzo della biomassa combustibile è di stretto interesse del settore agroforestale, per via del notevole indotto economico che peraltro interessa tutto il territorio nazionale. Tuttavia, la combustione della biomassa è legata ad una serie di problematiche ambientali quali le emissioni in atmosfera di polveri sottili che influenzano direttamente la qualità dell’aria. Si ritiene, quindi, che l’auspicato aumento dell’utilizzo delle biomasse, soprattutto ai fini della produzione di calore (riscaldamento ambienti), sia legata al contenimento delle emissioni al camino. In questo contesto, è quindi importante la corretta misura delle polveri emesse dagli apparecchi di riscaldamento domestico alimentati a biomassa solida, tenendo conto anche della frazione condensabile, come richiesto dalla normativa. Il lavoro mette a confronto due tecniche di misura delle polveri, la tecnica di prelievo a caldo con raffreddamento dei fumi in impinger e la tecnica di diluizione con tunnel. Sono stati selezionati per il confronto due apparecchi di ridotta potenza (< 15 kWt) ed elevata efficienza: una caldaia a pellet ed una stufa a pellet. In condizioni di combustione completa le due tecniche restituiscono fattori di emissione simili. Nella stufa a pellet la misura a freddo è maggiore del 20 – 30 % rispetto alla misura a caldo. La ridotta presenza della frazione condensabile è stata confermata dall’analisi NPOC degli impinger. Sono state misurate le emissioni totali prodotte da un utilizzo reale del dispositivo, comprendendo anche le fasi transitorie di combustione (accensione, riscaldamento a regime e spegnimento), solitamente non considerate nelle misure standard di laboratorio. La fase di accensione produce fino a tre volte le polveri emesse in condizioni stazionarie. L’emissione totale si riduce all’aumentare del tempo di utilizzo del dispositivo, rientrando nell’intervallo delle emissioni delle condizioni stazionarie dopo circa 6 h. Gli IPA, emessi in quantità elevate, sono costituiti maggiormente da congeneri a peso molecolare medio – basso, associati a minore tossicità. Il TEQ è funzione della potenza e delle condizioni di
combustione del dispositivo.

Die Verbrennung fester Biomasse gewinnt als nachhaltige Form der Energieerzeugung stetig an Bedeutung. Eine mögliche Technologie stellen dabei Biomasse-Thermoölkesselanlagen dar, deren Regelungen bis jetzt noch nicht auf einem mathematischen Modell basieren und dementsprechend deren verkoppeltes und zum Teil nichtlineares Verhalten nur ungenügend berücksichtigen. Ziel dieser Arbeit ist es, ein für Biomassefeuerungsanlagen mit Wasserkesseln existierendes Modell sowie die darauf aufbauende Regelungsstrategie an die speziellen Gegebenheiten von Thermoölkesselanlagen anzupassen. Dazu wird zunächst ein einfaches Modell für Thermoölwärmeübertrager auf Basis einer Energiebilanz hergeleitet und anhand von verfügbaren Betriebsdaten qualitativ verifiziert. Anschließend wird die bei der Regelung von Wasserkesselanlagen eingesetzte Eingangs-Ausgangslinearisierung verallgemeinert. Darauf aufbauend wird eine Regelungsstrategie zur Regelung des Thermoölwärmeübertragers hergeleitet. Die Leistungsfähigkeit des Regelungskonzeptes wird schließlich in Simulationsstudien gezeigt. 

 Im Bereich der thermischen Biomassenutzung (speziell Rostfeuerungen) werden CFD-Simulationen eingesetzt, um Hilfestellung bei der Diagnose und Lösung von Betriebsproblemen zu leisten sowie bei der Entwicklung von neuen Feuerungen und Kesseln zu unterstützen. Zurzeit sind keine Modelle verfügbar, mit denen sowohl die Vorgänge im Brennstoffbett als auch in der Gasphase einer Biomasse-Rostfeuerung mit Hilfe von detaillierten numerischen Modellen bei akzeptabler Berechungszeit simuliert werden können. Um die direkte Kopplung des Bett-Modells mit der Gasphase zu bewerkstelligen, ist es nötig, ein geeignetes Partikel-Modell zu entwickeln, welches die thermische Konversion (Trocknung, Pyrolyse und Holzkohle-Ausbrand) von thermisch dicken Biomassepartikeln beschreibt und mit bereits vorhandenen CFD-Modellen für die Gasphasensimulation gekoppelt werden kann. In diesem Schalenmodell werden die einzelnen Biomassepartikel als thermisch dick behandelt, d.h. die Temperaturgradienten in den einzelnen Partikeln sowie der gleichzeitige Ablauf mehrerer Umwandlungsprozesse berücksichtigt. Das Schalenmodell wurde mit Hilfe von gemessenen Partikeloberflächen- und -zentrumstemperaturen sowie mit Messwerten des Gesamtmasseverlustes während der Verbrennung in einem Einzel-Partikelreaktor validiert. Ein weiteres Problem, das bei der Simulation von Biomasse-Rostfeuerungen auftritt, ist die Modellierung der Gas-Festkörper-Mehrphasenströmung. Das Modell muss dabei in der Lage sein, den Einfluss der Partikel-Partikel-Wechselwirkung währenden der Partikelbewegung am Rost korrekt zu beschreiben. Aus diesem Grund wurde durch Kopplung von Euler- und Lagrange Mehrphasenströmungs- Ansätzen ein neues, dreidimensionales Schüttungsmodell entwickelt. Dabei wird die Partikelbewegung am Rost mit Hilfe eines Euler-Ansatzes (Euler-Granular-Modell) beschrieben, während die thermische Umwandlung der Biomassepartikel mit Hilfe eines Lagrange-Ansatzes und dem entwickelten Einzelpartikelmodell beschrieben wird. Das 3D-Festbettmodell für Biomasserostfeuerungen wurde eingesetzt, um eine 20 kW Biomasse-Unterschubfeuerung zu simulieren. Da es keine experimentelle Daten hinsichtlich der Bedingungen im Brennstoffbett gab, wurden qualitative Informationen hinsichtlich der Positionen der Trocknungs-, Pyrolyse- und Holzkohle-Ausbrandzonen, sowie mit Thermoelementen gemessenen Rauchgastemperaturen an verschiedenen Positionen in der Brennkammer zum Vergleich mit den Simulationsergebnissen herangezogen. Des Weiteren erfolgte im Zuge dieser Arbeit eine Weiterentwicklung des Festbett-Modells, indem der Strahlungsaustausch zwischen den Partikeln sowie detaillierte kinetische Modelle für die Gasphasenverbrennung im Modell implementiert wurden. Das weiterentwickelte Modell wurde mit Hilfe von experimentellen Daten aus Testläufen in einem Festbett-Laborreaktor validiert. Diese Messdaten beinhalten gemessene Konzentrationen von CO, CO2, CH4, H2, H2O und O2 im Rauchgas über dem Brennstoffbett sowie Temperaturen in unterschiedlichen Positionen im Bett und über dem Bett. Die vorhergesagten Werte zeigten eine gute Übereinstimmung mit den gemessenen Werten.

Für den ökonomisch und ökologisch effizienteren Betrieb von Dampfkesselanlagen ist die Untersuchung von Korrosionsvorgängen in Wärmetauschern, verursacht durch das Rauchgas aus einer Biomasse-Feuerung, notwendig. Daher wurden bei Bioenergy 2020+ kurzzeitige Korrosionsversuche im Umfang von 300h Betriebszeit an einem Wärmetauscherstahl 13CrMo4-5 mit einer ONLINE-Korrosionssonde der Firma Corrmoran GmbH für die Erstellung eines empirischen Korrosionsmodells durchgeführt. Als Brennstoffe dienten Waldhackgut, Weizenstrohpellets und Altholz. Die Messung benötigt eine Ionen leitende Deckschicht, die sich erst am Beginn des Versuchs aufbaut. Aufgrund der fehlenden Deckschicht wird daher zu Beginn der Messung der Korrosionsleitwert unterschätzt. Daraus ergeben sich systematische Messfehler. Ziel dieser Arbeit war die Eruierung des Zusammenhanges zwischen Messfehler und Versuchszeit. Dabei stellten sich zwei systematische Messfehler als relevant heraus: •Die Abzehrrate ist zum Korrosionsleitwert proportional. Daher wird die Abzehrrate während der Eingangsphase der Messung unterschätzt. •Die Abzehrrate berechnet sich aus dem Korrosionsleitwert, multipliziert mit einem Kalibrierungsfaktor. Dabei ergibt sich der Kalibrierungsfaktor aus dem Verhältnis des gesamten korrosionsbedingten Materialverlustes über die gesamte Versuchsdauer, dividiert durch den über denselben Zeitraum integrierten Korrosionsleitwert. Aufgrund des zu Beginn unterschätzten Korrosionsleitwertes wird der Kalibrierungsfaktor und somit die Abzehrrate, berechnet aus dem reproduzierbaren Signal, überschätzt. Die Literaturrecherche zeigte, dass die Kinetik bei der Hochtemperaturkorrosion bei konstant gehaltenen korrosionsrelevanten Parametern einen linearen, parabolischen oder paralinearen Verlauf einnehmen kann. Die kleinstmögliche Abzehrrate und somit der kleinstmögliche Korrosionsleitwert zu Beginn der Messung ergibt sich bei der Annahme eines linearen Verlaufs, welcher die möglicherweise erhöhten Abzehrraten der Initialkorrosion nicht mitberücksichtigt. Aus dieser Annahme konnte der kleinstmögliche Korrekturfaktor cmin berechnet werden. Dazu mussten die Daten bei konstant gehaltenen Parametern gefiltert und daraus der zeitlich integrierte Korrosionsleitwert PL,Messung gebildet werden. Das Verhältnis von PL,Messung mit einem über die gesamte Versuchszeit konstant angenommenen zeitlich integrierten Korrosionsleitwertes PL,linear ergibt den Korrekturfaktor, der multipliziert mit den ursprünglich bei gleichen Parametern bestimmten Abzehrraten eine neue Abzehrrate k(t)neu ergibt. Der Vergleich mit den Ergebnissen eines Langzeitversuches unter ähnlichen Betriebsbedingungen in einem Biomasse-Heizkraftwerk zeigte dadurch eine Verbesserung der Abweichung der Kurzzeitversuche von 125% auf 55%. Aufgrund der Parametervariationen sowie der Temperaturschwankungen, verursacht durch Ein- und Ausschaltvorgänge der Anlage, haben die bei konstanten Parametern bestimmten Korrekturfaktoren für die durchgeführten Versuche nur bedingt Gültigkeit. Daher wurde in einem weiteren Schritt ein Korrekturfaktor cmin,var bestimmt, welcher alle Daten der Versuchsserie berücksichtigt. Dazu wurde das Signal der Eingangsphase durch ein gleichlanges reproduzierbares Signal, gemessen unter denselben Bedingungen am Ende der Versuchsserien, ersetzt. Es ergibt sich aus dem Verhältnis der zeitlich integrierten Korrosionsleitwerte PL,Messung der Originalkurve zu PL,idealisiert des idealisierten Verlaufs der Korrekturfaktor cmin,var. Dieser hat aufgrund der Berücksichtigung aller gesammelten Daten für alle bei den Versuchen bestimmten Abzehrraten Gültigkeit. Durch cmin,var konnte eine Reduktion der Abweichung auf 110% erreicht werden. Diese wird auf die im Gegensatz zur Langzeitmessung im Biomasse-Heizkraftwerk unterschiedliche Versuchsmethode sowie auf den unbekannten Einfluss der möglicherweise erhöhten Abzehrraten der Initialkorrosion zurückgeführt.  

The use of biomass in manually charged room heating appliances to cover the domestic heating demand has traditionally been of a high percentage in the European Union. As a result of continued or even increased use of firewood stoves, the enhancement of available stoves is a declared objective of the European Union.
Therefore, an example-optimization of the firewood stove Stûv 16/78-in (available on the European market) was performed in preparation of this paper. There was a primary- and a secondary optimization carried out to quantify the potential of optimization. When optimizing, the gas and particulate emissions was considered. The operating behavior were measured and evaluated by performing combustion experiments on a specially designed test rig.
The primary optimization is divided into five sub-steps. Each Step was quantified by gas analysis. The achieved reduction of particulate emissions was measured before and after the entire primary optimization.
In comparison to the delivery condition it was possible to reduce the CO emissions to one quarter and the particulate emissions from 100 mg / mn³ to 39 mg / mn³ over the course of the primary optimization.
As a secondary optimization, a Catalyst was implemented. The used catalyst is a solid-state catalyst in the modification of a heterogeneous supported catalyst in the shape of honeycomb, which is marketed by Clariant International Ltd. under the name "EnviCat ® Longlife Plus". The catalytically active materials platinum and palladium are used.
After a strictly implemented primary optimizations, a further reduction to half of emissions was achieved by the integration of the catalyst even though a bypass of 20 % had to be integrated to ensure the operating safety.

To meet the aims of the worldwide effort to reduce greenhouse gas emissions, product gas from biomass steam gasification in DFB (dual fluidized bed) gasification plants can play an important role for the production of electricity, fuel for transportation and chemicals. Using a catalytically active bed material, such as olivine, brings advantages concerning tar reduction in the product gas. Experience from industrial scale gasification plants showed that a modification of the olivine occurs during operation due to the interaction of the bed material with ash components from the biomass and additives. This interaction leads to a calcium-rich layer on the bed material particles which influences the gasification properties and reduces tar concentration in the product gas. In this paper, the influence on the gasification performance, product gas composition and tar formation of a reduction of the gasification temperature are studied. A variation of the gasification temperature from 870 °C to 750 °C was carried out in a 100 kW pilot plant. A reduction of the gasification temperature down to 750 °C reduces the concentration of hydrogen and carbon monoxide in the product gas and increases the concentration of carbon dioxide and methane. The product gas volume produced per kg of fuel is reduced at lower gasification temperatures but the calorific value of the product gas increases. The volumetric concentration of tars in the product gas increases slightly until 800 °C and nearly doubles when decreasing the gasification temperature to 750 °C. The tars detected by gas chromatography-mass spectrometry (GCMS) were classified into substance groups and related to the fuel input to the gasifier and showed a decrease in naphthalenes and polycyclic aromatic hydrocarbons (PAHs) and an increase in phenols, aromatic compounds and furans when reducing the gasification temperature. The comparison with results from an earlier study, where the gasification properties of unused fresh olivine were compared with used olivine, underlines the importance of a long retention time of the bed material in the gasifier, ensuring the formation of a calcium-rich layer in the bed material. © 2012 Elsevier Ltd. All rights reserved.

The increasing demand for woody biomass increases the price of this limited resource, motivating the growing interest in using woody materials of lower quality as well as non-woody biomass fuels for heat production in Europe. The challenges in using non-woody biomass as fuels are related to the variability of the chemical composition and in certain fuel properties that may induce problems during combustion. The objective of this work has been to evaluate the technical and environmental performance of a 15. kW pellet boiler when operated with different pelletized biomass fuels, namely straw (Triticum aestivum), Miscanthus (Miscanthus× giganteus), maize (Zea mays), wheat bran, vineyard pruning (from Vitis vinifera), hay, Sorghum (Sorghum bicolor) and wood (from Picea abies) with 5% rye flour. The gaseous and dust emissions as well as the boiler efficiency were investigated and compared with the legal requirements defined in the FprEN 303-5 (final draft of the European standard 303-5). It was found that the boiler control should be improved to better adapt the combustion conditions to the different properties of the agricultural fuels. Additionally, there is a need for a frequent cleaning of the heat exchangers in boilers operated with agricultural fuels to avoid efficiency drops after short term operation. All the agricultural fuels satisfied the legal requirements defined in the FprEN 303-5, with the exception of dust emissions during combustion of straw and Sorghum. Miscanthus and vineyard pruning were the best fuels tested showing comparable emission values to wood combustion. © 2012 Elsevier Ltd.

A mathematical model is developed to simulate synthesis gas production by methane steam reforming process in a fixed bed reactor filled with catalyst particles. Due to the endothermic nature of the reforming reactions heat is supplied into the reactor by means of electrical heating, therefore, the reactor and catalyst particles are exposed to significant axial and radial temperature gradients. A pseudo heterogeneous model is used in order to exactly represent diffusion phenomena inside the reactor tube. Heat and mass transfer equations are coupled with detailed reaction mechanisms and solved for both the flow phase and within the catalyst pellets. The reaction has been investigated from a modeling view point considering the effect of different temperatures ranging from 873 to 1073 (K) on methane conversion and hydrogen yields. The result provides temperature and concentration distribution along the reactor axial and radial coordinates and strong radial temperature gradients particularly close to the entrance of the reactor have been found. © 2013 Elsevier B.V.

Current levels of ambient air fine particulate matter (PM_2.5) are associated with mortality and morbidity in urban populations worldwide. In residential areas wood combustion is one of the main sources of PM_2.5 emissions, especially during wintertime. However, the adverse health effects of particulate emissions from the modern heating appliances and fuels are poorly known. In this study, health related toxicological properties of PM₁ emissions from five modern and two old technology appliances were examined. The PM₁ samples were collected by using a Dekati® Gravimetric Impactor (DGI). The collected samples were weighed and extracted with methanol for chemical and toxicological analyses. Healthy C57BL/6J mice were intratracheally exposed to a single dose of 1, 3, 10 or 15mg/kg of the particulate samples for 4, 18 or 24h. Thereafter, the lungs were lavaged and bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation, cytotoxicity and genotoxicity. Lungs of 24h exposed mice were collected for inspection of pulmonary tissue damage. There were substantial differences in the combustion qualities of old and modern technology appliances. Modern technology appliances had the lowest PM₁ (mg/MJ) emissions, but they induced the highest inflammatory, cytotoxic and genotoxic activities. In contrast, old technology appliances had clearly the highest PM₁ (mg/MJ) emissions, but their effect in the mouse lungs were the lowest. Increased inflammatory activity was associated with ash related components of the emissions, whereas high PAH concentrations were correlating with the smallest detected responses, possibly due to their immunosuppressive effect. © 2012 Elsevier B.V.

Most of the current pyrolysis/torrefaction mechanisms are not able to predict the composition of pyrolysis/torrefaction products. They usually lump the products as permanent gases, liquids (condensable species) and solid residuals. However, the composition of the emitted species is required to predict the calorific value of the torrgas and to model the possible subsequent gas phase reactions and the temperature distribution within the reactor. Therefore, in this work a mechanism from literature is applied for the first time to predict the composition of the torrgas as a combination of twenty typical species. Several experimental data sets from literature are used to evaluate the mechanism. Since the mechanism predicts several relevant species (>1% wt.) in the torrgas for which no experimental data in the literature are available, test runs at a lab-scale packed bed reactor have been performed to achieve more detailed data of torrgas composition for model validation. Among the species for which measured data are available, carbon monoxide and methanol are well predicted. The predictions of carbon dioxide, methane, formaldehyde, acetaldehyde and ethanol are qualitatively correct. The predictions of water vapour, acetic acid, propanal, ethylene and sugar components show deviations. However, yields of solid residual and total emitted gas and tar are well predicted by the mechanism.

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.

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.

The bed material and especially its catalytic activity plays an important role in biomass steam gasification in dual fluidized bed gasifiers. The bed material is modified by interaction with biomass ash during operation of the gasification plant forming layers at the particles which are induced by the biomass ash. Optimization of dual fluidized biomass steam gasification will have significant influence on the process variables such as temperatures, inorganic composition and product gas composition. The influence of these changes on layer formation is still unknown. This paper summarizes results of investigations about bed material characteristics taken from the industrial-scale biomass steam gasification plant in Güssing where woody biomass is used as fuel. Analyses of the surface and the crystal structures of the bed material particles treated in gasification and combustion atmospheres were carried out. The thermal behavior of used olivine and fresh olivine in different atmospheres was analyzed. A suggestion for the mechanism of formation of the layers is presented and the influence of possible optimization measures is discussed. A change in the elemental composition of the surface was not detectable but a slight change in the crystal structure. Thermal investigations show a weak endothermic weight loss with used olivine in a CO₂-rich atmosphere which could not be determined with fresh olivine. The formation of layers at the olivine particles is considered to be caused by the intensive contact with burning char particles in the combustion reactor. © 2013 Elsevier B.V.

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

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

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

Synthesis gas from biomass can be produced and utilized in different ways. Conversion of biomass to synthesis gas can be done either in fluidized bed or entrained flow reactors. As gasification agent oxygen, steam, or mixtures are used. The most common use of biomass gasification in the last decades has been for heat and/or power production. Nowadays, the importance of transportation fuels from renewables is increased due to environmental aspects and growing fossil fuels prices. That is why the production of Fischer-Tropsch (FT) liquids, methanol, mixed alcohols, substitute natural gas (SNG), and hydrogen from biomass is now in focus of view. The most innovative and interesting ways of synthesis gas utilization and projects, BioTfueL or GoBiGas, BioLiq, Choren, etc. are discussed here. Further the microchannel technology by Oxford Catalysts and distributed production of SNG in decentral small scale are presented. The synthesis platform in Güssing, Austria is also presented. The FT liquids, hydrogen production, mixed alcohols, and BioSNG, these are the projects associated with the FICFB gasification plant in Güssing. Also the principle and examples of sorption-enhanced reforming to adjust H₂/CO ratio in product gas during the gasification is described. Finally, in the conclusion also an outlook for the thermochemical pathway to transportation fuels is given. WIREs Energy Environ 2014, 3:343-362. doi: 10.1002/wene.97 For further resources related to this article, please visit the WIREs website. © 2013 Wiley Periodicals, Inc.

Trace nutrients significantly affect the microbial metabolic activity within anaerobic digestion processes but always imply the risk of overdosing of heavy metals. In this study the applicability of a sequential extraction scheme established for soil and sediment samples on biogas slurries with different compositions was tested and compared to an adapted version of this extraction method. The analytical results proved the successful applicability of the developed analytical technique for the speciation of trace nutrients in anaerobic digestion systems. The procedure fulfills the basic requirements of reproducible data, a time-saving analytical approach and economic feasibility. Recovery rates of 90-110% were obtained for the most important trace elements Fe, Co, Cu, Mo, Ni and Zn. However, it was demonstrated that the adapted method provides more reliable information about the bioavailable fractions and it is considered the more appropriate approach. Data on fractionation indicated that up to 76% of these essential trace nutrients might be present in an insoluble state. Depending on the specific trace element a significant fraction, from 30% to more than 70%, is not directly bioavailable. This important aspect should be considered to guarantee sufficient supply of the microbial consortium with trace elements and at the same time to avoid overdosage. © 2014 Elsevier Ltd.

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 IPSE_pro. 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. IPSE_pro 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.

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.

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.

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

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.

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.

Producer gas from biomass gasification contains mainly hydrogen, carbon dioxide, carbon monoxide, methane and some other low molecular hydrocarbons like propylene. This paper reports mathematical simulation and experimental study of steam reforming of methane mixture with propylene in a packed bed reactor filled with nickel based catalysts. Due to the high heat input through the reformer tube wall and the endothermic reforming reactions, a two-dimensional pseudo-heterogeneous model that takes into account the diffusion reaction phenomena in gas phase as well as inside the catalyst particles has been used to represent temperature distribution and species concentration within the reactor. Steam reforming of propylene is faster and more selective than methane and it is shown that addition of propylene to the methane steam mixture reduces the conversion of methane. The obtained results play a key role in optimization and design of a commercial reactor. © 2014 Elsevier Ltd. All rights reserved.
 

Batch-wise operated wood stoves for room heating purposes are popular and widespread in Europe. Beside economic and ecological reasons they are also very important for reaching the European CO2 emission targets. However, since they contribute significantly to harmful gaseous as well as particulate emissions, they have to be optimized towards clear emission reduction in real life operation. Catalysts integrated in wood stoves can significantly contribute to reach this target. The results of this study showed an emission reduction potential of
integrated ceramic and metallic honeycomb catalysts of around 30 % to 99 %. Thereby the highest reduction potential was investigated for CO emissions (reduction rate 75 % to 99 %), followed by reductions of VOC emissions (reduction rate 40 % to 60 %) and reductions of PM emissions of around 30 % to 40 %. Long term tests and safety test series lead to the conclusion that integrated catalysts have to be cleaned regularly in order to prevent blocking and to guarantee optimal reduction performance.