Technical Reports | 2016
Strasser C. Technology Overview. New York State Wood Heat Report: An Energy, Environmental, and Market Assessment - Final Report. April 2016. Chapter 8; 141-206.
Conference contributions | 2019
Technology mapping of market-available small-scale combustion appliances
Feldmeier S, Wopienka E, Schwarz M, Pfeifer C. Technology mapping of market-available small-scale combustion appliances. 27th European Biomass Conference & Exhibition (Poster). 2019.
A broad range of different biomass combustion appliances dedicated to domestic heating is available on the market. Depending on the technology the impact of varying properties of biomass fuels on slag formation and emission release may vary. Aspects as the design of the grate section and the selection of individual boiler components as well as operational settings determine the applicability of biomass fuels. Apart from fuel properties also the fuel load on the grate, residence time, air distribution and geometry of grate and combustion chamber affect the degree of slag formation and emission release. Technology indexes determined by means of constructional measures enable a systematic comparison and – in a further step – an assessment of combustion appliances. In this work specific technology indexes were specified and applied to compare technological aspects, which will prospectively allow investigating the technological influence on the combustion performance.
Technical Reports | 2019
Technological expertise for biomass-based heat, power and transport fuels
Bacovsky D. Technological expertise for biomass-based heat, power and transport fuels. Bioenergy in Austria. October 2019.
Peer Reviewed Scientific Journals | 2014
Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers
Hebenstreit B, Schnetzinger R, Ohnmacht R, Höftberger E, Lundgren J, Haslinger W, et al. Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers. Biomass Bioenergy. 2014;71:12-22.
An active condensation system for the heat recovery of biomass boilers is evaluated. The active condensation system utilizes the flue gas enthalpy exiting the boiler by combining a quench and a compression heat pump. The system is modelled by mass and energy balances. This study evaluates the operating costs, primary energy efficiency and greenhouse gas emissions on an Austrian data basis for four test cases. Two pellet boilers (10kW and 100kW) and two wood chip boilers (100kW and 10MW) are considered. The economic analysis shows a decrease in operating costs between 2% and 13%. Meanwhile the primary energy efficiency is increased by 3-21%. The greenhouse gas emissions in CO2 equivalents are calculated to 15.3-27.9kg MWh-1 based on an Austrian electricity mix. The payback time is evaluated on a net present value (NPV) method, showing a payback time of 2-12 years for the 10MW wood chip test case. © 2014 Elsevier Ltd.
Peer Reviewed Scientific Journals | 2021
Techno-economic optimization of islanded microgrids considering intra-hour variability
Mathiesen P, Stadler M, Kleissl J, Pecenak Z. Techno-economic optimization of islanded microgrids considering intra-hour variability. Applied Energy. 2021.304:117777.
The intra-hour intermittency of solar energy and demand introduce significant design challenges for microgrids. To avoid costly energy shortfalls and mitigate outage probability, islanded microgrids must be designed with sufficient distributed energy resources (DER) to meet demand and fulfill the energy and power balance. To avoid excessive runtime, current design tools typically only utilize hourly data. As such, the variable nature of solar and demand is often overlooked. Thus, DER designed based on hourly data may result in significant energy shortfalls when deployed in real-world conditions. This research introduces a new, fast method for optimizing DER investments and performing dispatch planning to consider intra-hour variability. A novel set of constraints which operate on intra-hour data are implemented in a mixed-integer-linear-program microgrid investment optimization. Variability is represented by the single worst-case intra-hour fluctuation. This allows for fast optimization times compared to other approaches tested. Applied to a residential microgrid case study with 5-minute intra-hour resolution, this new method is shown to maintain optimality within 2% and reduce runtime by 98.2% compared to full-scale-optimizations which consider every time-step explicitly. Applicable to a variety of technologies and demand types, this method provides a general framework for incorporating intra-hour variability into microgrid design.
Conference contributions | 2020
Techno-economic modelling of bioeconomy value chains
Dißauer C, Fuhrmann M, Strasser C, Enigl M, Matschegg D. Techno-economic modelling of bioeconomy value chains. 6th Central European Biomass Conference. 2020. Graz.
In the context of Austria´s and the EU´s ambitious goals to combat climate change by reducing the demand for fossil fuels in all sectors, many industries plan to increase the share of renewable energy in their production processes. Furthermore greenhouse gases shall be reduced by 36 % until 2030 (compared to 2005), which means another 14 Mio. tons CO2eq will have to be reduced per year in comparison to data from 2016. In doing so, some industries find it sufficient to use green electricity or green gas from the grid, but for some industries the use of biomass is particularly interesting. In particular, the wood-based economy as an essential part of the Austrian bio-based economy is needed to promote the development of sustainable production and sustainable energy generation. Besides the increasing demand for woody biomass, the supply side will also undergo substantial changes since increasing calamities (such as bark beetle infestation and windthrow) caused by climate change will affect the wood supply to a varying extend. Hence, within the project “BioEcon” the BIOENERGY 2020+ team together with industry partners analyses the effects of these developments on the wood-based economy and the corresponding supply chains in terms of economic and technological perspectives including econometric models to evaluate woody biomass supply and demand.
Peer Reviewed Scientific Journals | 2017
Techno-economic assessment of hydrogen production based on dual fluidized bed biomass steam gasification, biogas steam reforming, and alkaline water electrolysis processes
Yao J, Kraussler M, Benedikt F, Hofbauer H. Techno-economic assessment of hydrogen production based on dual fluidized bed biomass steam gasification, biogas steam reforming, and alkaline water electrolysis processes. Energy Conversion and Management. 1 August 2017;145: 278-292.
Books / Bookchapters | 2020
Technische Optionen für die Umrüstung und Nachrüstung von Industrien mit Bioenergie
Rutz D, Janssen R, Reumerman P, Spekreijse J, Matschegg D, Bacovsky D, et al. Technische Optionen für die Umrüstung und Nachrüstung von Industrien mit Bioenergie. WIP Renewable Energies.2020
Contributions to trade journals | 2009
Tar content and composition in producer gas of fluidized bed gasification of wood - influence of temperature and pressure
Wolfesberger U, Aigner I, Hofbauer H. Tar content and composition in producer gas of fluidized bed gasification of wood-influence of temperature and pressure. Environmental Progress and Sustainable Energy. 2009;28(3):372-9.
Conference contributions | 2009
Tar Content and Composition in Producer Gas of Fluidized Bed Gasification and Low Temperature Pyrolysis of Straw and Wood – Influence of Temperature
Aigner I, Wolfesberger U, Hofbauer H. Tar Content and Composition in Producer Gas of Fluidized Bed Gasification and Low Temperature Pyrolysis of Straw and Wood – Influence of Temperature, ICPS 2009, 1st-3rd of September 2009, Vienna, Austria.
The global warming, the increasing CO2 emission, the combustion of and dependency on fossil
fuels, as well as the high-energy price have resulted in an increasing demand in renewable energy
sources. Biomass, as a renewable energy source, has the potential to contribute to the future energy
mix in various ways. In thermo-chemical biomass conversion processes, especially gasification and pyrolysis, the tar content and its composition is a major subject. Due to the various processes examined at VUT, this
work picks up the opportunity to compare the different tar amounts and compositions at different
temperatures and process parameters. The tar content and composition in the producer gas of steam
gasification of straw and wood as well as the tar yields of low temperature pyrolysis of straw are
displayed in the following work. Gasification experiments were carried out in a 100 kW dual fluidized bed steam gasifier at a temperature range of 700° C to 870° C. Pyrolysis experiments were conducted in a rotary kiln
reactor at temperatures between 600° C and 630° C. For better understanding of tar formation during thermo-chemical conversion of biomass the tar content and composition in the producer gas was analyzed with a gas chromatograph coupled with a mass spectrometer. Main observation was that at higher temperatures the tar composition is shifted to higher molecular tars as poly aromatic hydrocarbons (PAH). Key tar components at lower temperatures (pyrolysis) are phenols. These results give the opportunity to analyse tar formation in different thermochemical conversion steps, therefore, for the future a better understanding of tar formation in large scale facility’s should be gained. This means lower tar content in the producer gas for gasification processes and an achievement of required pyrolysis oil yields for pyrolysis.
Conference contributions | 2010
Tapping the energy contained in waste for renewable energy provision - example of Austria
Ragossnig A. Tapping the energy contained in waste for renewable energy provision - example of Austria, International Work-Shop ENERGY & FUELS FROM WASTE & BIOMASS 2010, 5th of January 2010, Pucon, Chile.
Technical Reports | 2021
Tailoring of the pore structures of wood pyrolysis chars for potential use in energy storage applications
Maziarka P, Sommersacher P, Wang X, Kienzl N, Retschitzegger S, Prins W, Hedin N, Ronsse F. Tailoring of the pore structures of wood pyrolysis chars for potential use in energy storage applications. Applied Energy.2021.286:116431. https://doi.org/10.1016/j.apenergy.2020.116431
Char obtained from biomass pyrolysis is an eco-friendly porous carbon, which has potential use as a material for electrodes in supercapacitors. For that application, a high microporous specific surface area (SSA) is desired, as it relates to the accessible surface for an applied electrolyte. Currently, the incomplete understanding of the relation between porosity development and production parameters hinders the production of tailor-made, bio-based pyrochars for use as electrodes. Additionally, there is a problem with the low reliability in assessing textual properties for bio-based pyrochars by gas adsorption. To address the aforementioned problems, beech wood cylinders of two different lengths, with and without pre-treatment with citric acid were pyrolysed at temperatures of 300–900 °C and analysed by gas adsorption. The pyrolyzed chars were characterised with adsorption with N2 and CO2 to assess the influence of production parameters on the textual properties. The new approach in processing the gas adsorption data used in this study demonstrated the required consistency in assessing the micro- and mesoporosity. The SSA of the chars rose monotonically in the investigated range of pyrolysis temperatures. The pre-treatment with citric acid led to an enhanced SSA, and the length of the cylinders correlated with a reduced SSA. With pyrolysis at 900 °C, the micro-SSAs of samples with 10 mm increased by on average 717 ± 32 m2/g. The trends among the investigated parameters and the textual properties were rationalized and provide a sound basis for further studies of tailor-made bio-based pyrochars as electrode materials in supercapacitors.
Scientific Journals | 2018
Tackling ammonia inhibition for efficient biogas production from chicken manure: Status and technical trends in Europe and China
Fuchs W, Wang X, Gabauer W, Ortner M, Li Z. Tackling ammonia inhibition for efficient biogas production from chicken manure: Status and technical trends in Europe and China (Review). Renewable and Sustainable Energy Reviews 2018;97:186-199.
The increased global consumption of chicken products has resulted in the generation of huge amounts of manure. Numerous studies emphasized the large potential of this waste as an untapped source of renewable energy through anaerobic digestion (AD). However, intrinsic difficulties, in particular the high N content, induce instable process conditions, including the accumulation of intermediates, and foaming, which reduces methane yields. Such issues limit the widespread application of this energy-rich substrate for biogas production. The process inhibition by ammonia is usually prevented by reducing the concentration of chicken manure through dilution or by operating the plant considerably below its theoretical reactor capacity. However, this process compromises process efficiency, thereby increasing capital investments and operational costs. Another option to achieve optimal process performance is co-digestion with less N-rich materials. However, co-digestion also has its limitations due to the frequent unavailability of sufficient amounts of C-rich substrates. A series of promising technical solutions have been developed to overcome the aforementioned bottlenecks. Examples include stripping or membrane extraction as means to reduce ammonia concentration in the fermenter. Several full-scale plants employing ammonia removal techniques have been installed recently. Latest research also investigated the use of additives, such as zeolites and trace elements, as well as bioaugmentation, to mitigate ammonia inhibition. The current study reviews the state of technology as well as recent achievements and perspectives. It provides an overview of the different approaches to remove ammonia from AD-process and presents practical examples from China and Europe.
Conference contributions | 2012
System performance of a storage integrated pellet boiler
Aigenbauer S, Hartl M, Malenkovic I, Simetzberger A, Vverma VK, Schmidl C. System performance of a storage integrated pellet boiler, 20th European Biomass Conference 2012, 18th-22nd of June 2012, Milano, Italy. p 1320-1324.
A pellet burner directly integrated into the solar storage provides heat and domestic hot water for small
residential applications in an environment-friendly way. The objective of this work was to evaluate the system
performance of a storage integrated pellet boiler in laboratory under transient test conditions. Furthermore, the type
test results according to ÖNORM EN 303-5  of the last decade were compared with monitoring data of systems
with separated boiler and heat storage. The laboratory tests allowed finding relevant parameters and losses, which
influence the system performance. A developed computer simulation model shows the potential to optimize the
performance of the investigated boiler.
Conference contributions | 2013
Synthetic biofuels – do they have a future?
Rauch R. Synthetic biofuels – do they have a future? 8th A3PS Conference Eco-Mobility 2013, 4th of October 2013, Vienna, Austria.
Conference contributions | 2014
Synergies of Wastewater and Microalgae Cultivation
Sonnleitner A, Bacovsky D, Bochmann G, Drosg B, Schagerl M. Synergies of Wastewater and Microalgae Cultivation, Word Sustainable Energy Days next 2014, 26th-28th of February 2014, Wels, Austria.
Current international research results identify microalgae as a new and promising feedstock for the global energy supply chain. A novel concept to reduce costs and cover the need of water and nutrients is the combination of wastewater treatment and microalgae cultivation. In Austria in particular brewery and dairy effluents as well as municipal wastewater would be suitable for algae cultivation. Cultivation systems practical for the use of wastewater are High Rate Algal Ponds (open system, suspended culture), Algal Turf Scrubbers (open system, immobilized culture) and Photobioreactors (closed systems, suspended culture). The cultivation of microalgae in general and the special case of wastewater as nutrient source face a variety of challenges either concerning the accumulation of microalgal cells in wastewater (upstream process) or their removal and processing (downstream process). Taking a look at the whole production chain shows that for effluents of breweries, dairies
and smale-scale municipal wastewater no feasible concept for the combination of microalgae cultivation and wastewater treatment can be designed. A promising production concept for large-scale municipal wastewater treatment plants are HRAPs or biofilm production in ATS systems for energetic and material pathways. Various R&D challenges are to overcome to lead to an optimization and further development of technologies for combined wastewater treatment and microalgae cultivation in Austria.
Technical Reports | 2019
Synchronization of the gas production and utilization rates of a solid-to-gas process and a downstream gas-to-X process
Nigitz T, Gölles M, Aichernig C, Hofbauer H, Horn, M. Synchronization of the gas production and utilization rates of a solid-to-gas process and a downstream gas-to-X process. 21. Styrian Workshop on Automatic Control. 10 September 2019. Leitring/Wagna, Austria. (oral presentation)
Other Presentations | 2015
Survey of modern pellet boilers in Austria and Germany - System design and customer satisfaction of residential installations
Büchner D, Schraube C, Carlon E, von Sonntag J, Schwarz M, Verma VK, Ortwein A. Survey of modern pellet boilers in Austria and Germany - System design and customer satisfaction of residential installations. Applied Energy;160: 390-403.
The variety of available technical building equipment leads to increasingly complex heating systems with various requirements for efficient operation. Furthermore, in existing buildings the heating system is often historically evolved and contains parts having different ages. Those systems have limited capacity to suit the requirements of replaced components. This paper investigates the operational behavior of small-scale pellet heating systems in Austria and Germany, considering installations in new buildings and boiler replacements in existing buildings and how they are influencing the customer satisfaction.
This investigation was carried out by means of a comprehensive survey for residential customers using pellet fired heating systems. More than 2500 questionnaires were distributed between 2011 and 2013 in Austria, Germany, Greece, Spain and the United Kingdom. In total 293 returned questionnaires were evaluated. The efficiency of the monitored heating systems was estimated using surveyed boiler parameters. Successively, the influence of different operational parameters on the boilers efficiency was evaluated with a statistical analysis, using Pearson correlation coefficient and Spearman correlation.
Results showed that the correct installation of the monitored pellet heating system is easier for new buildings compared to the replacement of old fossil boilers in existing buildings. Optimal operating conditions are characterized by less frequent ignitions and by higher operational loads. Pellet systems operated with a high efficiency in both building types, but for new buildings it is more likely to occur. More than 87% of the participating customers stated that they are highly satisfied with their pellet boiler.
Peer Reviewed Scientific Journals | 2020
Surface characterization of ash-layered olivine from fluidized bed biomass gasification
Kuba M, Fürsatz K, Janisch D, Aziaba K, Chlebda D, Łojewska J, Forsberg F, Umeki K, Hofbauer H. Surface characterization of ash-layered olivine from fluidized bed biomass gasification. Biomass Conversion and Biorefinery. 2020
The present study aims to present a comprehensive characterization of the surface of ash-layered olivine bed particles from dual fluidized bed gasification. It is well known from operation experience at industrial gasification plants that the bed material is activated during operation concerning its positive influence on gasification reactions. This is due to the built up of ash layers on the bed material particles; however, the chemical mechanisms are not well understood yet. Olivine samples from long-term operation in an industrial-scale gasification plant were investigated in comparison to fresh unused olivine. Changes of the surface morphology due to Ca-enrichment showed a significant increase of their surface area. Furthermore, the Ca-enrichment on the ash layer surface was distinctively associated to CaO being present. The presence of CaO on the surface was proven by adsorption tests of carbon monoxide as model compound. The detailed characterization contributes to a deeper understanding of the surface properties of ash layers and forms the basis for further investigations into their influence on gasification reactions.
Technical Reports | 2021
Supervisory control of large-scale solar thermal systems
Task 55 Towards the Integration of Large SHC Systems into DHC Networks
Gölles M, Unterberger V, Kaisermayer V, Nigitz T, Muschick D. "Supervisory control of large-scale solar thermal systems". IEA SHC FACTSHEET 55.A-D4.1. Date of Publication: 28.01.2021. https://task55.iea-shc.org/fact-sheets
Overview on different approaches for supervisory control strategies,deciding on operating modes and set points for the controls of the different plants and componentsintegrated in solar thermal systems.
Conference contributions | 2013
Suitable gasification methods and gas cleaning schemes for BtL application of producer gas
Rauch, R. New processes for fuel conversion, gas cleaning and CO2 separation in FB and EF gasification of coal, biomass and waste, Workshop ” Suitable gasification methods and gas cleaning schemes for BtL application of producer gas” (held during the First International Workshop on New processes for fuel conversion, gas cleaning and CO2 separation in FB and EF gasification of coal, biomass and waste) 12th-14th of June, Prague, Czech, 2013.
Conference contributions | 2022
Success Factors and Barriers for Integrated District Heating Networks
Muschick D, Cronbach D, Ianakiev A, Kallert A, Schmidt R-R, Sorknaes P et al. Success Factors and Barriers for Integrated District Heating Networks. 2022. Postersitzung präsentiert bei 2nd International Sustainable Energy Conference , Graz, Österreich.
Conference contributions | 2008
Straw pellets combustion in small-scale boilers. Part 2: Corrosion and material optimization.
Emhofer W, Wopienka E, Schwabl M, Friedl G. Straw pellets combustion in small-scale boilers. Part 2: Corrosion and material optimization, 16th European Biomass Conference 2008, 2nd-6th of June 2008, Valencia, Spain. p1500-1503.
This paper presents one part of the results of a project dealing with straw pellets combustion in small
scale combustion systems. Whereas the other part of the work investigates gaseous and particulate emissions, this part focuses on the results of experiments to determine corrosion of refractory material. Three different types of straw
pellets are combusted in a prototype of a 15 kW residential heating boiler. The fuel samples are natural wheat straw,
wheat straw with alumina based additive and wheat straw with a mixture of calcium-/magnesium carbonate based
additive. Combustion experiments are performed under different operating conditions of the test boiler. Three
different types of refractory material are used as combustion chamber material. The refractory materials are different
mixtures of alumina, silica, zirconia and silicium-carbide. The degree of deterioration of these materials is
investigated for temperatures between 700 and 1300 deg C in the presence of slag formed during combustion of the
straw samples and the influence of the fuel additives on corrosion effects is analysed.
Conference contributions | 2008
Straw pellets combustion in small-scale boilers. Part 1: Emissions and emission reduction with a novel heat exchanger technology.
Wopienka E, Schwabl M, Emhofer W, Friedl G, Haslinger W, Wörgetter M, Merkl R, Weissinger A. Straw pellets combustion in small-scale boilers. Part 1: Emissions and emission reduction with a novel heat exchanger technology, 16th European Biomass Conference 2008, 2nd-6th of June 2008, Valencia, Spain. p 1386-1392.
Contributions to trade journals | 2014
Strategy for the application of novel characterization methods for biomass fuels: Case study of straw
Obernberger I. Strategy for the application of novel characterization methods for biomass fuels: Case study of straw. Energy and Fuels. 2014;28(2):1041-52.
Because of an increasing interest in the utilization of new and in terms of combustion-related properties rather unknown biomass fuels in heat and power production, advanced fuel characterization tools are gaining rising interest. Currently, ongoing research and development (R&D) focuses on a better and more precise description of the combustion properties of specific biomass fuels by applying new/advanced analysis methods and modeling tools. These novel characterization methods cover combustion tests in specially designed lab reactors, special fuel indices for biomass fuels, and the dedicated application of high-temperature equilibrium calculations. In this paper, a strategy is presented how the information gained from different advanced fuel characterization methods can be combined to characterize a fuel regarding its combustion behavior in a novel way. By means of this strategy, relevant qualitative and quantitative information regarding the ash-melting behavior, aerosol, SOx, HCl, and NOx emissions to be expected, and high-temperature corrosion risks can be gained. In addition, the approach can also be used for the evaluation of additives and fuel blending as measures to improve specific combustion properties. The results show that a much better and clearer picture about the combustion properties of a specific biomass fuel can be provided than by conventional approaches (such as wet chemical analysis or other standardized methods). The results can be used for the preliminary design of plants as well as for evaluation of the applicability of a specific technology for a certain biomass fuel or fuel spectrum. Moreover, they can be applied in combination with computational fluid dynamics (CFD) simulations for the detailed design and evaluation of furnaces and boilers. © 2014 American Chemical Society.