A promising way to substitute fossil fuels for production of electricity, heat, fuels for transportation and synthetic chemicals is biomass steam gasification in a dual fluidized bed (DFB). Using lower-cost feedstock, such as logging residues, instead of stemwood, improves the economic operation. In Senden, near Ulm in Germany, the first plant using logging residues is successfully operated by Stadtwerke Ulm. The major difficulties are slagging and deposit build-up. This paper characterizes inorganic components of ash forming matter and draws conclusions regarding mechanisms of deposit build-up. Olivine is used as bed material. Impurities, e.g., quartz, brought into the fluidized bed with the feedstock play a critical role. Interaction with biomass ash leads to formation of potassium silicates, decreasing the melting temperature. Recirculation of coarse ash back into combustion leads to enrichment of critical fragments. Improving the management of inorganic streams and controlling temperature levels is essential for operation with logging residues.

State-of-the-art packed bed models supply continuous concentration profiles as boundary conditions for subsequent CFD simulations of gas phase, leading to pre-mixed combustion conditions. However, in reality the “porous” nature of the packed bed leads to streak formation influencing gas mixing and combustion. Therefore, in the present work, in order to account for the influence of the streaks on gas phase combustion, a gas streak model based on a correlation between the local gas residence time and a mixing time has been developed based on numerical simulations. Finally, the streak model was linked with an in-housed developed hybrid gas phase combustion model suitable for laminar to highly turbulent flow conditions and applied for an under-feed pellet stoker furnace (20 kW_th) concerning the simulation of gas phase combustion and NO_x formation. The results in comparison with a simulation without the streak formation model show that the flue gas species prediction can be improved with the proposed streak formation model. Especially, in the region above the fuel bed (in the primary combustion chamber), this is of special importance for NO_x reduction by primary measures.

State-of-the-art packed bed models supply continuous concentration profiles as boundary conditions for subsequent CFD simulations of gas phase, leading to pre-mixed combustion conditions. However, in reality the “porous” nature of the packed bed leads to streak formation influencing gas mixing and combustion. Therefore, in the present work, in order to account for the influence of the streaks on gas phase combustion, a gas streak model based on a correlation between the local gas residence time and a mixing time has been developed based on numerical simulations. Finally, the streak model was linked with an in-housed developed hybrid gas phase combustion model suitable for laminar to highly turbulent flow conditions and applied for an under-feed pellet stoker furnace (20 kW_th) concerning the simulation of gas phase combustion and NO_x formation. The results in comparison with a simulation without the streak formation model show that the flue gas species prediction can be improved with the proposed streak formation model. Especially, in the region above the fuel bed (in the primary combustion chamber), this is of special importance for NO_x reduction by primary measures.

Abattoirs have a large number of energy intensive processes. Beside energy supply, disposal costs of animal by-products (ABP) are the main relevant cost drivers. In this study, successful implementation of a new waste and energy management system based on anaerobic digestion is described. Several limitations and technical challenges regarding the anaerobic digestion of the protein rich waste material had to be overcome. The most significant problems were process imbalances such as foaming and floatation as well as high accumulation of volatile fatty acids and low biogas yields caused by lack of essential microelements, high ammonia concentrations and fluctuation in operation temperature. Ultimately, 85% of the waste accumulated during the slaughter process is converted into 2700 MW h thermal and 3200 MW h electrical energy in a biogas combined heat and power (CHP) plant. The thermal energy is optimally integrated into the production process by means of a stratified heat buffer. The energy generated by the biogas CHP-plant can cover a significant share of the energy requirement of the abattoir corresponding to 50% of heat and 60% of electric demand, respectively. In terms of annual cost for energy supply and waste disposal a reduction of 63% from 1.4 Mio € to about 0.5 Mio € could be achieved with the new system. The payback period of the whole investment is approximately 9 years. Beside the economic benefits also the positive environmental impact should be highlighted: a 79% reduction of greenhouse gas emissions from 4.5 Mio kg CO₂ to 0.9 Mio kg CO₂ annually was achieved. The realized concept received the Austrian Energy Globe Award and represents the first anaerobic mono-digestion process of slaughterhouse waste worldwide.

Wärmeversorgungsanlagen von Gebäuden, bestehend aus Biomasse-Feuerung, Solarkollektoren, Pufferspeicher, Heizkreis und Warmwasserzapfstellen gewinnen aufgrund ihrer Nachhaltigkeit zunehmend an Bedeutung. In den letzten Jahren wurden insbesondere für eine effiziente Regelung der Biomasse-Feuerung sehr gute Konzepte entwickelt. Diese können jedoch zumeist aufgrund unzureichender, übergeordneter Systemregelungen nicht ihr volles Potential ausschöpfen. In ihrer primitivsten Ausführung schaltet eine Systemregelung die Biomasse-Feuerung anhand der Ladehöhe des Pufferspeichers aus und ein. Diese Art der Regelung hat unweigerlich viele Ein-/ Ausschaltvorgänge der Feuerung, sowie eine schlechte Ausnutzung des solaren Eintrags zur Folge. Insbesondere bei Biomasse-Feuerungen sind Ein-/ Ausschaltvorgänge äußerst unwirtschaftlich und führen zu stark erhöhten Schadstoffemissionen. Die häufigen Ein-/ Ausschaltvorgänge verursachen zusätzlich erhöhte Wartungs- und Betriebskosten und schlussendlich eine verkürzte Lebensdauer zahlreicher Komponenten. Um die Ein-/ Ausschaltvorgänge zu minimieren und den solaren Eintrag zu steigern, soll im Rahmen dieser Arbeit ein übergeordnetes, modellprädiktives Regelungskonzept für die gesamte Wärmeversorgungsanlage entwickelt werden. Nach einer theoretischen Einführung in gemischt-ganzzahlige Optimalsteuerungsprobleme sowie ausgewählter Lösungsmethoden werden Prädiktionsmodelle für alle Komponenten der Wärmeversorgungsanlage entwickelt. Aufbauend auf den mathematischen Modellen für die einzelnen Komponenten der Anlage wird eine nichtlineare modellprädiktive Regelung entwickelt. Diese berücksichtigt zusätzlich Wetterprognosen sowie die erwartete Lastabnahme und führt schlussendlich zu einer Minimierung des Brennstoffverbrauchs sowie der Anzahl der Ein-/ Ausschaltvorgänge. Den Abschluss der Arbeit bilden ausführliche Simulationsstudien mit unterschiedlichen Wetterszenarien sowie Vergleiche mit herkömmlichen Regelungsstrategien.  

Nowadays dynamic building simulation is an essential tool for the design of heating systems for residential buildings. The simulation of buildings heated by biomass systems, first of all needs detailed boiler models, capable of simulating the boiler both as a stand-alone appliance and as a system component. This paper presents the calibration and validation of a boiler model by means of laboratory tests. The chosen model, i.e. TRNSYS "Type 869", has been validated for two commercially available pellet boilers of 6 and 12. kW nominal capacities. Two test methods have been applied: the first is a steady state test at nominal load and the second is a load cycle test including stationary operation at different loads as well as transient operation. The load cycle test is representative of the boiler operation in the field and characterises the boiler's stationary and dynamic behaviour. The model had been calibrated based on laboratory data registered during stationary operation at different loads and afterwards it was validated by simulating both the stationary and the dynamic tests. Selected parameters for the validation were the heat transfer rates to water and the water temperature profiles inside the boiler and at the boiler outlet. Modelling results showed better agreement with experimental data during stationary operation rather than during dynamic operation. Heat transfer rates to water were predicted with a maximum deviation of 10% during the stationary operation, and a maximum deviation of 30% during the dynamic load cycle. However, for both operational regimes the fuel consumption was predicted within a 10% deviation from the experimental values. © 2014 Elsevier Ltd.

The high temperature water gas shift reaction (HTS) over an iron/chromium (Fe/Cr) industrial catalyst was investigated in a pilot scale plant consisting of two fixed-bed reactors arranged in series and a biomass-derived tar-rich synthesis gas was used as a feed-stream. CO conversion and selectivity for the water gas shift reaction were evaluated through parameter variation. Four dry gas hourly space velocities (GHS_v) and two steam to dry synthesis gas ratios (H₂O/SG_d) equal to 52% v/v and 60% v/v were investigated at temperatures (T) of 350–450 °C. CO conversion was investigated by varying H₂S concentration 180–540 ppmv (dry basis) at a temperature of 425 °C, considering two GHSV_d. The highest CO conversion (~ 83%) was observed in the basis case at 60% v/v H₂O/SG_d, and 450 °C. The catalyst appeared to be resistant to sulfur poisoning deactivation, and achieved 48% CO conversion at the maximum H₂S concentration used.

This study investigates the general concept of reduced firebed temperatures in residential wood pellet boilers. Residential wood pellet boiler development is more and more concerned with inorganic aerosols characterized by a temperature-dependent release from the firebed. Hence, different concepts are applied aiming to reduce firebed temperatures. Unfortunately, these concepts influence not only firebed temperatures, but also other important parameters like air flow rates which may cause unwanted side effects with respect to combustion quality or efficiency. Thus, a new approach was developed solely affecting firebed temperature by implementing a water-based firebed cooling in a 12 kW underfeed pellet boiler. The effectiveness of the cooling was monitored by comprehensive temperature measurement in the firebed. The cooling capacity ranged from 0.4 kW to 0.5 kW resulted in a significant decrease of firebed temperatures. Gaseous emissions remain stable showing no significant changes in major components (O₂, CO₂, NO_x). Furthermore, CO emissions were even reduced significantly by the activated cooling, which was supposedly caused by a stabilized devolatilization due to the firebed cooling. Moreover, the temperature-dependent release of aerosol forming elements was influenced at activated firebed cooling, which is proved by a decrease of 17 wt% of dust (Total Suspended Particles; TSP). At the same time the gaseous emissions of HCl increase, supposedly by a reduced potassium release from the firebed to the gas phase and a subsequently different particle formation. The general concept of reduced firebed temperatures proved to be successful decreasing overall aerosol emissions without impacting combustion quality.

High-temperature corrosion in biomass fired boilers is still an insufficiently explored phenomenon which causes unscheduled plant shutdowns and hence, economical problems. To investigate the high-temperature corrosion and deposit formation behaviour of superheater tube bundles, online corrosion probe as well as deposit probe measurements have been carried out in a specially designed fixed bed/drop tube reactor in order to simulate a superheater boiler tube under well-controlled conditions. The investigated boiler steel 13CrMo4-5 is commonly used as steel for superheater tube bundles in biomass fired boilers. Forest wood chips and quality sorted waste wood (A1-A2 according to German standards) as relevant fuels have been selected to investigate the influence on the deposit formation and corrosion behaviour. The following influencing parameter variations have been performed during the test campaigns: flue gas temperature between 650 and 880°C, steel temperature between 450 and 550°C and flue gas velocity between 2 and 8 m/s. One focus of the work presented is the detailed investigation of the structure and the chemical composition of the deposits formed as well as of the corrosion products. A further goal of the work presented was the development of an empirical model which can be used within CFD simulations of flow and heat transfer to calculate and evaluate the local corrosion potential of biomass fired plants already at the planning stage. The corrosion probe measurements show a clear dependency on the parameters investigated and the empirical function developed reproduces the measured corrosion behaviour sufficiently accurate. Since the additional calculation time within the CFD simulation is negligible the model represents a helpful tool for plant designers to estimate whether high-temperature corrosion is of relevance for a certain plant or not, when using fuels with similar compositions and the steel 13CrMo4-5. © 2014 Elsevier Ltd. All rights reserved.

An efficient utilization of biomass fuels in power plants is often limited by the melting behavior of the biomass ash, which causes unplanned shutdowns of the plants. If the melting temperature of the ash is locally exceeded, deposits can form on the walls of the combustion chamber. In this paper, a bubbling fluidized bed combustion chamber with 50 MW biomass input is investigated that severely suffers deposit build-up in the freeboard during operation. The deposit layers affect the operation negatively in two ways: they act as an additional heat resistance in regions of heat extraction, and they can come off the wall and fall into the bed and negatively influence the fluidization behavior. To detect zones where ash melting can occur, the temperature distribution in the combustion chamber is calculated numerically using the commercial CPFD (computational particle fluid dynamics) code, Barracuda Version 15. Regions where the ash melting temperature is exceeded are compared with the fouling observed on the walls in the freeboard. The numerically predicted regions agree well with the observed location of the deposits on the walls. Next, the model is used to find an optimized operating point with fewer regions in which the ash melting temperature is exceeded. Therefore, three cases with different distributions of the inlet gas streams are simulated. The simulations show if the air inlet streams are moved from the freeboard to the necking area above the bed a more even temperature distribution is obtained over the combustion chamber. Hence, the areas where the ash melting temperatures are exceeded are reduced significantly and the formation of deposits in the optimized operational mode is much less likely.

In this paper, the performance of a commercial Fe/Cr based catalyst for the water gas shift reaction was investigated. The catalyst was used in a water gas shift pilot plant which processed real product gas from a commercial biomass steam gasification plant with two different qualities: extracted before and extracted after scrubbing with a rapeseed methyl ester gas scrubber. The performance of the WGS pilot plant regarding these two different gas qualities was investigated. For this reason, extensive chemical analyses were carried out. CO, CO₂, CH₄, N₂, O₂, C₂H₆, C₂H₄, and C₂H₂ and H₂S, COS, and C₄H₄ S were measured. In addition, GCMS tar and NH₃ analyses were performed. Furthermore, the catalyst's activity was observed by measuring the temperature profiles along the reactors of the water gas shift pilot plant. During the 200 h of operation with both product gas qualities, no catalyst deactivation could be observed. A CO conversion up to 93% as well as a GCMS tar reduction (about 28%) along the water gas shift pilot plant was obtained. Furthermore, a specific H₂ production of 63 g H₂ per kg biomass (dry and ash free) was reached with both product gas qualities. No significant performance difference could be observed.

The interest in experimental data regarding thermal fuel decomposition as well as the release behavior of ash-forming elements of biomass fuels for modeling and simulation purposes is continuously increasing. On the basis of combustion experiments with lab-scale reactors and single-particle reactors, integral release data regarding ash-forming vapors can be obtained, whereby the release is calculated on the basis of analysis data of the fuel and the ash residues. At the moment, almost no time-resolved release data of ash-forming elements from single particles exist. Therefore, a single-particle reactor was designed, which has been coupled to an inductively coupled plasma mass spectrometer (ICP-MS). This reactor can be used for targeted experiments in a temperature range of 250–1050 °C under inert, reducing, and oxidizing conditions. With this reactor, it is possible to simultaneously determine the surface and center temperatures of a biomass particle, weight loss of the particle, and flue gas composition. The reactor has been coupled to an ICP-MS through a gas stream that is sufficiently diluted with Ar. First performance tests with pure salts (KCl, NaCl, (NH₄)₂SO₄, ZnCl₂, and PbCl₂) proved that relevant volatile ash-forming elements can be detected with the ICP-MS. For a further validation of the received signals, combustion tests with Miscanthus pellets have been carried out, whereby the controlled interruption of the experiments has also been investigated. These tests prove that with this system the simultaneous time-resolved determination of S, Cl, K, Na, Zn, and Pb is possible whereby the Cl signal can only be used with restrictions. On the basis of the determined release of ash-forming elements for the entire combustion experiment, a quantification/calibration of the measured intensities has been carried out. The data gained from these tests will provide deeper insights into release processes as well as form a relevant basis for release model development.

In modern buildings with tight shells, often room-independent air supply is required for proper operation of biomass stoves. One possibility to arrange this supply is to use a double-wall chimney with flue gas leaving through the pipe and fresh air entering through the annular gap. A one-dimensional quasi-static model based on balance equations has been developed and compared with experimental data. Inclusion of leak air is crucial for reproduction of the experimental results. © 2014, Springer-Verlag Berlin Heidelberg.

Biochar is the product of biomass pyrolysis and gasification. One of the possible application of this product is certainly in agronomic sector, as soil amendment. However biochar use in Italy is subordinated to insert this product in fertilizer list, which biochar could be commercialized with. The aim of this paper is to know the biochar from gasification process (using an Imbert downdraft prototype), in particular investigating its potentiality as soil amendment in terms of European and Italian regulations and in terms of physical and chemical characterizations.

Wood pellets have been reported to emit toxic gaseous emissions during transport and storage. Carbon monoxide (CO) emission, due to the high toxicity of the gas and the possibility of it being present at high levels, is the most imminent threat to be considered before entering a pellet storage facility. For small-scale (<30 tons storage capacity) residential pellet storage facilities, ventilation, preferably natural ventilation utilizing already existing openings, has become the most favored solution to overcome the problem of high CO concentrations. However, there is little knowledge on the ventilation rates that can be reached and thus on the effectiveness of such measures. The aim of the study was to investigate ventilation rates for a specific small-scale pellet storage system depending on characteristic temperature differences. Furthermore, the influence of the implementation of a chimney and the influence of cross-ventilation on the ventilation rates were investigated. The air exchange rates observed in the experiments ranged between close to zero and up to 8 m³h^-1, depending largely on the existing temperature differences and the existence of cross-ventilation. The results demonstrate that implementing natural ventilation is a possible measure to enhance safety from CO emissions, but not one without limitations. © 2014 © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

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.