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Conference Papers | 2016

Investigations of a dual fluidized bed steam gasification plant by means of computation particle fluid dynamics

Kraft S, Kirnbauer F, Hofbauer H. Investigations of a dual fluidized bed steam gasification plant by means of computation particle fluid dynamics. 24th European Biomass Conference & Exhibition (oral presentation). June 2016, Amsterdam, Netherlands.

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Other Publications | 2016

Market integration of wood fuels and heating oil

Kristöfel C, Strasser C, Schmid E, Morawetz UB. Market integration of wood fuels and heating oil. 24th European Biomass Conference & Exhibition (poster). June 2016, Amsterdam, Netherlands.

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Conference contributions | 2016

Mathematische Modellierung mittlerer bis großer Solaranlagen als Basis für modellbasierte Regelungsstrategien

Unterberger V, Lichtenegger K, Innerhofer P, Gerardts B, Gölles M. Mathematische Modellierung mittlerer bis großer Solaranlagen als Basis für modellbasierte Regelungsstrategien. Gleisdorf Solar 2016. Gleisdorf: 2016. (Auszeichnung als innovativstes Poster).

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Peer Reviewed Scientific Journals | 2016

Mechanism of Layer Formation on Olivine Bed Particles in Industrial-Scale Dual Fluid Bed Gasification of Wood

Kuba M, He H, Kirnbauer F, Skoglund N, Boström D, Öhman M, Hofbauer H. Mechanism of Layer Formation on Olivine Bed Particles in Industrial-Scale Dual Fluid Bed Gasification of Wood. Energy & Fuels. 15 September 2016;30(9): 7410-7418.

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Utilization of biomass as feedstock in dual fluidized bed steam gasification is a promising technology for the substitution of fossil energy carriers. Experience from industrial scale power plants showed an alteration of the olivine bed material due to interaction with biomass ash components. This change results mainly in the formation of Ca-rich layers on the bed particles. In this paper, a mechanism for layer formation is proposed and compared to the better understood mechanism for layer formation on quartz bed particles. Olivine bed material was sampled at an industrial scale power plant before the start of operation and at pre-defined times after the operation had commenced. Therefore, time dependent layer formation in industrial-scale conditions could be investigated. The proposed mechanism suggests that the interaction between wood biomass ash and olivine bed particles is based on a solid-solid substitution reaction, where Ca2+ is incorporated into the crystal structure. As a consequence Fe2+/3+ and Mg2+ ions are expelled as oxides. This substitution results in the formation of cracks in the particle layer due to a volume expansion in the crystal structure once Ca2+ is incorporated. The results of this work are compared to relevant published results including those related to quartz bed particles.
 


Peer Reviewed Scientific Journals | 2016

Methodological approaches for fractionation and speciation to estimate trace element bioavailability in engineered anaerobic digestion ecosystems: An overview

van Hullebusch ED, Guibaud G, Simon S, Lenz M, Yekta SS, Fermoso FG, Jain R, Duester L, Roussel J, Guillon E, Skyllberg U, Almeida CMR, Pechaud Y, Garuti M, Frunzo L, Esposito G, Carliell-Marquet C, Ortner M, Collins G. Methodological approaches for fractionation and speciation to estimate trace element bioavailability in engineered anaerobic digestion ecosystems: An overview. Critical Reviews in Environmental Science and Technology. 17 August 2016;46(16): 1324-1366.

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Conference contributions | 2016

Mixed alcohol synthesis based on wood gas derived from dual fluidized bed biomass steam gasification - applying a rapeseed oil methyl ester gas scrubber for gas conditioning

Binder, M., Rauch, R., Hofbauer, H., 2016, "Mixed alcohol synthesis based on wood gas derived from dual fluidized bed biomass steam gasification - applying a rapeseed oil methyl ester gas scrubber for gas conditioning", poster presentation at BioResTec2016 - 1st International Conference on Bioresource Technology for Bioenergy, Bioproducts & Environmental Sustainability , 23 - 26 October 2016, Sitges, Spain.

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Peer Reviewed Scientific Journals | 2016

Modification of Co/Al2O3 Fischer–Tropsch Nanocatalysts by Adding Ni: A Kinetic Approach

Nikparsa P, Mirzaei AA, Rauch R. Modification of Co/Al2O3 Fischer–Tropsch Nanocatalysts by Adding Ni: A Kinetic Approach. International Journal of Chemical Kinetics. 1 March 2016;48(3): 131-142.

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Other Presentations | 2016

On site monitoring and dynamic simulation of a low energy house heated by a pellet boiler

Carlon E, Schwarz M, Prada A, Golicza L, Verma V, Baratieri M, Gasparella A, Haslinger W, Schmidl C. On site monitoring and dynamic simulation of a low energy house heated by a pellet boiler. 15 March 2016;116: 296-306.

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Prefabricated low energy houses are becoming increasingly popular thanks to their low cost and high energy performance. Heating systems installed in these houses should be optimally designed and controlled, to ensure thermal comfort for the whole heating season.

This study presents the on-site monitoring and dynamic simulation of a low energy house heated by a pellet boiler via a floor heating system. The house combines a lightweight envelope, a heat distribution system with a high thermal inertia and a biomass-based heat supply. The one-year monitoring campaign allowed to closely investigate the system's response to the heat demand. Moreover, a coupled simulation of the house and its heating and hot water supply system was set-up, calibrated, and validated against measured indoor temperature profiles and energy consumptions. Root mean square deviations between simulated and measured indoor temperature were in the range 0.4–0.8 K, while simulated energy consumptions fulfilled the criteria of the ASHRAE 14-2002 Guideline. As monitoring data evidenced the importance of better managing the high thermal inertia of the floor heating system, two improved control strategies were tested in the simulation environment and evaluated in terms of thermal comfort, pellet consumption and efficiency of the pellet boiler.


Conference contributions | 2016

Overview on advanced biofuels technologies

Bacovsky D. Overview on advanced biofuels technologies. Bioenergy Australia 2016. November 2016, Brisbane, Australia.

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Conference Papers | 2016

Phase Sewparation Behaviour of FAME and Water

Bardolf R, Thoma C, Bosch K, Rauch R, Hofbauer H. Phase Sewparation Behaviour of FAME and Water. 24th European Biomass Conference & Exhibition (poster). June 2016, Amsterdam, Netherlands.

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Conference Papers | 2016

Possibility of industrial scale BioH2 production from product gas in existing dual fluidized bed biomass gasification plant

Jovanovic A, Stamenkovic M, Nenning L, Rauch R. Possibility of industrial scale BioH2 production from product gas in existing dual fluidized bed biomass gasification plant. 4th International Symposium on Environment Friendly Energies and Applications, EFEA 2016. 18 November 2016, Belgrade, Serbia.

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Conceptual solution of production of pure renewable hydrogen from wood gas or product derived from the commercial biomass steam gasification plant Güssing, Austria was carried out. The proposed process of product gas upgrading consisted of tree basic operations: (I) catalyzed water-gas shift (WGS) reaction, (II) gas drying and cleaning in a wet scrubber and (III) hydrogen purification by pressure swing adsorption. The tail gas or adsorbate can be used like fuel for gas engine for electrical energy production or like a boiler fuel for hot water-heat production.


Technical Reports | 2016

Production of advanced biofuels

Bacovsky D. Production of advanced biofuels. Nationaler Workshop Biotreibstoffe. September 2016.

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Conference Papers | 2016

Progress in hydrogen production from product gas generated by dual fluidized bed biomass steam gasification

Kraussler M, Hofbauer H. Progress in hydrogen production from product gas generated by dual fluidized bed biomass steam gasification. 24th European Biomass Conference & Exhibition (oral presentation). June 2016, Amsterdam, Netherlands.

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Other Publications | 2016

Progress in Mixed Alcohol Synthesis - Based on Wood Gas Derived from Dual Fluidized Bed Biomass Steam Gasification

Binder, M., Weber, G., Rauch, R., Hofbauer, H.: Progress in Mixed Alcohol Synthesis - Based on Wood Gas Derived from Dual Fluidized Bed Biomass Steam Gasification. Poster presentation at CASCATBEL workshop 2016, 18 - 20 May 2016, Porto Carras, Greece.

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Peer Reviewed Scientific Journals | 2016

Reaction mechanisms and multi-scale modelling of lignocellulosic biomass pyrolysis

Anca-Couce, A. Reaction mechanisms and multi-scale modelling of lignocellulosic biomass pyrolysis. Progress in Energy and Combustion Science. Volume 53, March 2016, Pages 41–79.

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In this work about pyrolysis of lignocellulosic biomass, the individual reaction mechanisms of cellulose, hemicellulose and lignin are initially described. The recent advances in the understanding of the fundamental reaction pathways are described, including quantum-mechanical calculations, and the description of pyrolysis as a two-step process, i.e., primary pyrolysis and secondary charring, the effect of the presence of an intermediate liquid compound, and the influence of inorganic species are discussed.

The need to describe biomass pyrolysis as the sum of the contributions of its individual components is then emphasised. The process of determining biomass mass loss kinetics is analysed, and the product composition and heat of reaction that are experimentally obtained during pyrolysis are presented, along with detailed schemes that can be used to predict them.

Finally, it is demonstrated that a multi-scale consideration of pyrolysis on multiple levels – specifically, on molecular, particle and reaction levels – is required to accurately describe biomass pyrolysis. Intra-particle phenomena and particle models are discussed and the reactor level is analysed with a focus placed on fixed bed and fluidised bed pyrolysis. In summary, a list of 10 research focal points that will be important in the future is presented.


Peer Reviewed Scientific Journals | 2016

Short term online corrosion measurements in biomass fired boilers. Part 2: Investigation of the corrosion behavior of three selected superheater steels for two biomass fuels

Retschitzegger, S., Gruber, T., Brunner, T., Obernberger, I. Short term online corrosion measurements in biomass fired boilers. Part 2: Investigation of the corrosion behavior of three selected superheater steels for two biomass fuels. Fuel Processing Technology. Volume 142, February 2016, Pages 59-70.

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The high temperature corrosion behavior of the boiler steels 13CrMo4-5 (1.7335), P91 (1.4903) and 1.4541 has been investigated during short-term test runs (~ 500 h) at a biomass fired grate furnace combined with a drop tube. For the test runs performed with 13CrMo4-5 and P91 chemically untreated wood chips have been used as fuel, whereas waste wood has been used for test runs with P91 and 1.4541. Online corrosion probes and a mass loss probe have been used applying a methodology developed in a previous study to correct for a measurement error occurring during short-term measurements with online corrosion probes (mass loss correction). Furthermore, deposit probe measurements have been performed to evaluate the deposit build-up rate and the chemical composition of deposits. SEM/EDX analyses of the corrosion probes have been performed subsequently to the test runs to gain information regarding the chemical composition and structure of the deposits as well as the corrosion layers.

The furnace has been operated at constant load to ensure constant combustion conditions. The flue gas temperature at the probes has been varied between 740 and 900 °C and the probe surface temperature has been varied between 400 and 560 °C in order to determine their influence on the corrosion rate.

General trends determined by the variation of these temperatures were similar for all boiler steels: the corrosion rate increased with increasing flue gas temperature and also with increasing probe surface temperature. For chemically untreated wood chips combustion at low flue gas temperatures (740 °C) the corrosion rates were comparable for 13CrMo4-5 and P91 at all probe surface temperatures. However, at flue gas temperatures of 800 °C and higher P91 showed better corrosion resistance than 13CrMo4-5. For waste wood combustion 1.4541 generally showed a better corrosion resistance than P91.

The mass loss correction of the measurement error occurring in the initial phase resulted in different errors of 55% for 13CrMo4-5 and 32% for P91 for chemically untreated wood chips. For waste wood the mass loss correction resulted in errors of 55% for P91 and 77% for 1.4541. The results from the mass loss determination for the waste wood test runs scattered stronger compared to the wood chips test runs. Therefore, the fits were not that accurate and the error margin was higher. However, the results outline that the mass loss correction is relevant in order to achieve a meaningful comparison of different short-term test runs using online corrosion probes.


Peer Reviewed Scientific Journals | 2016

Simultaneous Online Determination of S, Cl, K, Na, Zn, and Pb Release from a Single Particle during Biomass Combustion. Part 2: Results from Test Runs with Spruce and Straw Pellets

Sommersacher P, Kienzl N, Brunner T, Obernberger I. Simultaneous Online Determination of S, Cl, K, Na, Zn, and Pb Release from a Single Particle during Biomass Combustion. Part 2: Results from Test Runs with Spruce and Straw Pellets. Energy and Fuels. 21 April 2016;30(4): 3428-3440.

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To gain better insight into inorganic element release processes, test runs with a specially designed single particle reactor connected with an inductively coupled plasma mass spectrometer (ICP-MS) have been performed. Relevant combustion related parameters such as mass loss during thermal degradation, temperature development of the particle (surface and center), and composition of released gases were recorded. By coupling the reactor to an ICP-MS, time-resolved release profiles of relevant aerosol forming elements (S, Cl, K, Na, Zn, and Pb) were determined. Targeted and controlled interruptions of the experiments (quenching) after a certain time were performed to validate reactor performance and reliability of the measurements. Test runs with softwood and straw pellets (8 mm in diameter and about 20 mm in length) were performed at reactor temperatures of 700, 850, and 1000 °C under oxidizing conditions (5.6 or 4.2 vol % O2). These test runs have revealed that the release ratios of volatile and semivolatile ash forming elements (S, Cl, K, Na, Zn, and Pb) generally increase as reactor temperatures rise. Moreover, regarding straw, higher Si and Al contents influence the release behavior of K, Na, Zn, and Pb. For K, existing release mechanisms proposed in the literature have been confirmed, and for Na it has been suggested that release mechanisms similar to K prevail. Especially during the starting phase of the experiment, a distinct temperature gradient exists from the surface to the center of the particle. Thus, different conversion phases occur in parallel in different layers of the particle, which has to be considered during the interpretation of the time-resolved release profiles of the main inorganic elements. Furthermore, transport limitations due to the occurrence of molten phases (especially for straw at reactor temperatures of 1000 °C) were obvious and could be directly derived from the online recorded release profiles. The targeted interruption of the ongoing decomposition process (quenching) provided an indication of the validity of the release profiles for S, K, Na, Zn, and Pb. Additionally, these experiments delivered valuable information regarding possible release mechanisms.


Technical Reports | 2016

Technology Overview

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

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Peer Reviewed Scientific Journals | 2016

The influence of oxygen availability on off-gassing rates of emissions from stored wood pellets

Meier F, Sedlmayer I, Emhofer W, Wopienka E, Schmidl C, Haslinger W, Hofbauer H. The influence of oxygen availability on off-gassing rates of emissions from stored wood pellets. Energy & Fuels. 18 February 2016;30(2): 1006-1012.

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The phenomenon of off-gassing from wood pellets during storage has been the cause of several, in some cases fatal, accidents due to toxic atmospheres in storages. To optimize safety measures the nature of the responsible processes needs to be clarified. In this study the impact of O2 availability, which is a decisive factor for the presumed oxidation of fatty acids, is pointed out. Off-gassing rates of CO, CO2, VOC, and CH4 of pellets at relatively constant O2 levels of approximately 35%, 20%, and <1% over a period of 20 d at approximately 295 K were investigated. For this purpose 7 kg of spruce pellets was stored under simulated ventilation of the atmosphere in a 31 L tank. Gas concentrations were determined every 24 h by GC-FID/TCD. Compared to the mean emission rates at 35% O2 of CO (0.22 mg kg–1pelletsd.b. in 24 h) and CO2 (0.76 mg kg–1pelletsd.b. in 24 h) the lowest O2 concentration of <1% resulted in a significant reduction of off-gassing rates of 40% for both gases. In contrast the release rates of VOCs and also CH4 decreased with the higher O2 concentration (0.035 to 0.025 mg kg–1pelletsd.b. in 24 h; 0.0085 to 0.0061 mg kg–1pelletsd.b. in 24 h), presumably, because of increased onward reactions to CO and CO2. Since off-gassing was not prevented by the lack of O2 (<1% O2-trial) it is assumed that the O2 required for the reactions originated from the biomass itself. During the storage of pellets at 20% O2, emission rates of CO (0.18 mg kg–1pelletsd.b. in 24 h) and CO2 (0.79 mg kg–1pelletsd.b. in 24 h) at the start decreased by more than 20% and those for VOCs (0.032 mg kg–1pelletsd.b. in 24 h) by almost 30% after 3 weeks. It can be assumed that in ventilated storages the reactivity and thus a potential risk from off-gases from wood pellets decreases considerably in only a few weeks. The effects of aging, in terms of declining reactivity at relatively constant tank conditions, on off-gassing rates could be clarified for the first time. A realistic development of the decline of reactivity of the material itself could be determined.


Peer Reviewed Scientific Journals | 2016

The interplay of self-reflection, social interaction and random events in the dynamics of opinion flow in two-party democracies

Lichtenegger K, Hadzibeganovic T. The interplay of self-reflection, social interaction and random events in the dynamics of opinion flow in two-party democracies. International Journal of Modern Physics C. 1 May 2016;27(5).

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We propose a continuous process opinion formation model to study the dynamics of a multi-level relationship between voters, political parties, and facts in two-party democratic elections. In our model, opinions can take any real value between two extremes and an unaligned, moderate opinion state without a preference. Starting with a random opinion configuration, individual voter opinions evolve and change over time due to self-reflection, inter-personal communication, external media influence, and noise. Parties are influenced by their own ideologies, facts, and voters’ opinions. Elections are held periodically and the party that is closer in opinion to the majority of voters forms the new government. The government policy is then expected to be in proximity to the voter opinions and the policies of the currently ruling political party. We analyze the tension of opinions as a measure of how dramatically opinions can disagree within a given sample of voters and the success of the government and parties as the degree of coincidence between the policies and facts. Our model generates realistic quasi-periodic alternations between incumbents and challengers that are typical for two-party systems. Moreover, our model shows that relative to other voters’ strategies, conscious voting can lead to more successful governments of not only fact-oriented but also pragmatic and balanced political parties, irrespective of the strategies of the competing opposition parties. In addition, our simulations uncover several interesting features including less victories for strictly ideological or fact-oriented parties unless they include some aspects of populism or pragmatism. In this sense, our model can also describe situations where election outcomes are not necessarily based on votes for the current programs of competing parties and their placement on relevant issues, but instead result from voters’ dissatisfaction with the previous government and the votes against it.


Read More: http://www.worldscientific.com/doi/abs/10.1142/S0129183116500650

Peer Reviewed Scientific Journals | 2016

The Virtual Biomass Grate Furnace - An Overall CFD Model for Biomass Combustion Plants

Ali Shiehnejadhesar, Ramin Mehrabian, Robert Scharler, Christoph Hochenauer. The Virtual Biomass Grate Furnace - An Overall CFD Model for Biomass Combustion Plants. 24rd European Biomass Conference & Exhibition (poster).

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This paper presents the virtual biomass grate furnace, which comprises of comprehensive CFD models of all relevant processes for the simulation of biomass grate furnaces. The models consist of a 3D packed bed model, a gas phase combustion model for laminar to highly turbulent flows and a model to account for the influence of the flue gas streaks arising from the fuel bed in the freeboard. The simulation results of a 20 kW underfeed stoker furnace show that the overall CFD model is able to provide valuable insight on the processes occurring in the packed bed and freeboard and their interactions.


Contributions to trade journals | 2016

The wood pellet market in Austria: A structural market model analysis

Christa Kristöfel, Christoph Strasser, Erwin Schmid, Ulrich B. Morawetz, The wood pellet market in Austria: A structural market model analysis, Energy Policy, Volume 88, January 2016, Pages 402-412,

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Peer Reviewed Scientific Journals | 2016

Thermal Stability of Bed Particle Layers on Naturally Occurring Minerals from Dual Fluid Bed Gasification of Woody Biomass

Kuba M, He H, Kirnbauer F, Skoglund N, Boström D, Öhman M, Hofbauer H. Thermal Stability of Bed Particle Layers on Naturally Occurring Minerals from Dual Fluid Bed Gasification of Woody Biomass. Energy & Fuels. 20 October 2016;30(10): 8277-8285.

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The use of biomass as feedstock for gasification is a promising way of producing not only electricity and heat but also fuels for transportation and synthetic chemicals. Dual fluid bed steam gasification has proven to be suitable for this purpose. Olivine is currently the most commonly used bed material in this process due to its good agglomeration performance and its catalytic effectiveness in the reduction of biomass tars. However as olivine contains heavy metals such as nickel and chromium no further usage of the nutrient-rich ash is possible and additional operational costs arise due to necessary disposal of the ash fractions. This paper investigates possible alternative bed materials and their suitability for dual fluid bed gasification systems focusing on the behavior of the naturally occurring minerals olivine, quartz and K-feldspar in terms of agglomeration and fractionation at typical temperatures. To this end samples of bed materials with layer formation on their particles were collected at the industrial biomass combined heat and power (CHP) plant in Senden, Germany, which uses olivine as the bed material and woody biomass as feedstock. The low cost logging residue feedstock contains mineral impurities such as quartz and K-feldspar which become mixed into the fluidized bed during operation. Using experimental analysis and thermochemical it was found that the layers on olivine and K-feldspar showed a significantly lower agglomeration tendency than quartz. Significant fractionation of particles or their layers could be detected for olivine and quartz, whereas K-feldspar layers were characterized by a higher stability. High catalytic activity is predicted for all three minerals once Ca-rich particle layers are fully developed. However quartz may be less active during the build-up of the layers due to lower amounts of Ca in the initial layer formation.
 


Conference Papers | 2016

Thermochemische Behandlung eines niederkalorischen Reststoffes zur Gewinnung von Sekundärrohstoffen

Meirhofer M, Dißauer C, Strasser C, Kranner R, Wartha C. Thermochemische Behandlung eines niederkalorischen Reststoffes zur Gewinnung von Sekundärrohstoffen. e-nova 2016 (oral presentation). November 2016, Pinkafeld, Austria.

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Reviewed Conference Papers | 2016

Toxicological characterization of particulate emissions from straw, Miscanthus, and poplar pellet combustion in residential boilers

Kasurinen S, Jalava PI, Uski O, Happo MS, Brunner T, Mäki-Paakkanen J, Jokiniemi J, Obernberger I, Hirvonen MR. Toxicological characterization of particulate emissions from straw, Miscanthus, and poplar pellet combustion in residential boilers. Aerosol Science and Technology. 2 January 2016;50(1): 41-51.

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Wood pellets have been used in domestic heating appliances for three decades. However, because the share of renewable energy for heating will likely rise over the next several years, alternative biomass fuels, such as short-rotation coppice or energy crops, will be utilized. We tested particulate emissions from the combustion of standard softwood pellets and three alternative pellets (poplar, Miscanthus sp., and wheat straw) for their ability to induce inflammatory, cytotoxic, and genotoxic responses in a mouse macrophage cell line. Our results showed clear differences in the chemical composition of the emissions, which was reflected in the toxicological effects. Standard softwood and straw pellet combustion resulted in the lowest PM1 mass emissions. Miscanthus sp. and poplar combustion emissions were approximately three times higher. Emissions from the herbaceous biomass pellets contained higher amounts of chloride and organic carbon than the emissions from standard softwood pellet combustion. Additionally, the emissions of the poplar pellet combustion contained the highest concentration of metals. The emissions from the biomass alternatives caused significantly higher genotoxicity than the emissions from the standard softwood pellets. Moreover, straw pellet emissions caused higher inflammation than the other samples. Regarding cytotoxicity, the differences between the samples were smaller. Relative toxicity was generally highest for the poplar and Miscanthus sp. samples, as their emission factors were much higher. Thus, in addition to possible technical problems, alternative pellet materials may cause higher emissions and toxicity. The long-term use of alternative fuels in residential-scale appliances will require technological developments in both burners and filtration.


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