Char originating from biomass can be used as a sustainable carbon additive in the production of polymer compounds with enhanced characteristics.

In this work, the fate of the ash-forming elements during bubbling fluidized bed combustion and gasification of P-rich sewage sludge (SS) and mixtures with either Si-K-rich wheat straw (WS) or K-Ca-rich sunflower husks (SH) were investigated. The focus of the study was assessing the feasibility of using fuel blends in fluidized bed systems and potential P recovery from the resulting ashes. The used fuels were pure SS and mixtures including 90 wt.% WS (WSS) and 85 wt.% SH (SHS). The analyzed operating conditions were combustion (930–960 °C, λ: 1.2–1.5) and gasification (780–810 °C, λ: 0.4–0.7) in a 5 kW bench-scale reactor. Residual ash and char fractions were collected from different parts of the 5 kW bubbling fluidized bed (bed, cyclone, filter) and analyzed by CHN, SEM/EDS, XRD, and ICP-AES.

The conversion of the fuel mixtures achieved a steady state under the used process conditions except for the combustion of WSS, which led to the formation of large bed agglomerates with the bed material. The morphology of ash samples after combustion showed that SS fuel pellets mostly maintained their integrity during the experiment. In contrast, the ash and char particles from fuel mixtures were fragmented, and larger quantities were found in the cyclone, the filter, or on interior reactor surfaces. The fate of P was dominated by crystalline Ca-dominated whitlockites in all ash fractions, partially including K for the fuel mixtures SHS and WSS. 76–81 % of ingoing P was found in the bed residue after combustion and gasification of the SS-fuel. After conversion of the fuel mixtures SHS and WSS, the share was lower at 22–48 %, with larger shares of P in the entrained fractions (25–34 %). The quantity of identified crystalline compounds was lower after gasification than combustion, likely due to the limited interaction of ash-forming elements in the residual CHN matrix. Altogether, the results show that fuel mixtures of sewage sludge with agricultural residues could expand the fuel feedstock and enable P recovery. This may be used in the fuel and process design of upscaled fluidized bed processes or systems employing both combustion and gasification.

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.

Management of municipal and commercial waste in Austria frequently involves mechanical-biological treatment (MBT) followed by incineration. A middle-caloric MBT output stream (lower heating value (LHV) = 9.90 MJ/kg WW, particle size = 20-80 mm) with a high proportion of inert material like stones, bricks, and metals (40.5 %m) is currently incinerated. Under favorable market conditions, it could be economically advantageous to split off a low-caloric heavy fraction (HF) that can be landfilled and to incinerate only the remaining, lighter fraction (LF) with a higher heating value. This study analyzes the specific global-warming potential (100-year GWP per tonne of input waste) of such an additional separation step and of the subsequent treatment processes. Four treatment alternatives were considered: a reference scenario without separation and three separation scenarios – a near-infrared (NIR) sensor-based scenario, an X-ray-transmission (XRT) sensor-based scenario, and a mechanical separation scenario using a diagonal sifter (DS). To calculate the specific GWP, the analysis applied techniques from life-cycle assessment (LCA). Primary data were obtained from pilot-scale and full-scale separation experiments, and from equipment manufacturers. Commercial databases provided secondary data. The results consist of separate LCA models for each scenario, including credits for fossil fuels replaced by LF incineration and HF landfill gas utilization. When only direct separation-related emissions are considered, the DS separation has by far the lowest specific GWP, followed by NIR-based separation, and by XRT-based separation. Overall specific GWP is strongly influenced by the choice of separation technology. It is lowest for the XRT scenario, followed closely by the reference scenario, while the DS and NIR scenarios show considerably higher results. Results are dominated by the net emissions from LF incineration. While incineration emissions are largely compensated by credits from replaced fossil fuels, credits for landfill gas utilization are much smaller than direct landfilling emissions. The ranking of the separation scenarios is largely determined by three waste stream characteristics: the ratio of biogenic to fossil carbon content and the LHV in the LF, and the degradable biogenic carbon content in the HF. Changes in important modeling assumptions leave the ranking between scenarios unchanged. It can be concluded that – given the right choice of
separation technology – a small positive effect of sorting on the overall specific GWP is feasible. This
work demonstrates that global warming effects of waste treatment decisions can be estimated and
considered early in the planning stage of treatment system design.

Integrating thermoelectric generators (TEGs) with photovoltaic (PV) devices presents an effective strategy to enhance the power generation of PV cells, thus substantially contributing to the widespread adoption of solar energy. By harnessing both photon and heat energy from sunlight, this integration maximizes energy capture and improves overall system efficiency, thereby advancing the feasibility and scalability of solar energy generation. This article provides a timely review of the advances and challenges in hybrid photovoltaic-thermoelectric generator (PV-TEG) technology, covering fundamentals, the impact of thermal, contact, and load resistance on performance, various integration options (such as hybrid PV-TEG systems with spectral splitters, phase change materials, and thermal systems), thermal management, feasibility, economic and environmental aspects, and long-term efficiency improvements. Following a detailed analysis and review of extensive progress, PV-TEG systems demonstrate higher efficiency across diverse environmental conditions compared to standalone PV devices. Finally, we address constraints, propose potential remedies, and point out future directions in the field.

Catalytic systems integrated in firewood stoves represent a potential secondary measure for emission reduction. However, the evaluation of catalytic efficiency is challenging since measurements, especially for PM emissions, upstream an integrated catalyst are not possible. Therefore, a special test facility, called “DemoCat”, was constructed which enabled parallel measurements in catalytically treated and untreated flue gas. The catalytic efficiency for CO, OGC and PM emissions was investigated under real-life operating conditions including ignition and preheating. The results confirmed a significant emission reduction potential (CO: > 95%, OGC: > 60%, PM: ∼30%). The conversion rates of CO and OGC emissions correlated with the space velocity and the coated area of honeycomb carriers which represent key parameters for the integration design. A quick response of the catalytic effect of around 5–12 min after ignition was observed when reaching 250 °C flue gas temperature at the catalyst. Most effective CO and OGC emission conversion was evident during the start-up and burn-out phase of a firewood batch. This reveals an important synergy for primary optimization which focuses particularly on the stretched intermediate phase of a combustion batch. The catalytic effect on PM emissions, especially on chemical composition, needs further investigations.

Fluidized bed gasification of sewage sludge is a promising method for its valorisation due to the fuel flexibility of the process. The main drawbacks are the impurities present in the producer gas, with a high tar content, and its low calorific value. In this study, sewage sludge and wood mixtures are gasified in a fluidized bed. A tar cracking reactor is used to reduce the amount of tars and to increase the calorific value of the producer gas. Sewage sludge char is employed for tar cracking with a real producer gas, showing the feasibility of the process with a tar conversion of about 80% at the beginning. The test was conducted for several hours and tar deactivation was observed, which lead to a decrease of tar conversion to about 35% after 5 hours. Reactivating the char with steam increases again the tar conversion up to 84%, however, the subsequent deactivation was found to be faster compared to the one for fresh char. First tests using char from the gasification process in the tar cracking unit also show promising results.

The market offers a broad range of different combustion appliances dedicated to residential heating with biomass. The effect of fuel properties on the formation of slag and emissions varies and the technology influences the impact to a certain extent. The applicability of biomass fuels is not only determined by operational settings but also by the design of boiler components as grate area and combustion chamber. Aspects as the fuel load on the grate, residence time, geometry of grate and combustion chamber design, as well as feeding and de-ashing influence the extent of slag formation and emission release. The determination of characteristic numbers by means of constructional measures allows a systematic comparison and - in a further step - an assessment/categorization of combustion technologies. After conducting a boiler survey relevant parameters regarding grate, combustion chamber, feeding, and ash removal were gathered. Characteristic numbers were specified in order to compare technological aspects. The results of this study allow the investigation of the influence of the combustion technology on the performance. They will assist the systematic and targeted design of small-scale boilers and the optimization of combustion appliances in future, especially when it comes to fuel-flexibility.

Straw, Miscanthus, maize, and horse manure were reviewed in terms of fuel characteristics. They were tested in existing boilers, and the particulate and gaseous emissions were monitored. The ash was analyzed for the presence of sintered material. All the fuels showed problems with ash lumping and slag formation. Different boiler technologies showed different operational performances. Maize and horse manure are problematic fuels regarding NO_x and particulate emissions. Miscanthus was the best fuel tested. Due to the big variation of fuel properties and therefore combustion behavior of agricultural biomass, further R&D is required to adapt the existing boilers for these fuels.

Biomass boilers used for residential heating and hot water supply are typically combined with a buffer storage and solar collectors. However, the annual utilization rates typically achieved with such systems are far below those theoretically possible, which is mainly because of the often poor quality of both the individual control of the components as well as the high-level control of the entire system. The control strategies typically applied consist of simple decou-pled control circuits with linear controllers, which cannot deal with the mostly nonlinear and coupled behaviour of the components and thus do not ensure their reasonable interaction. The most appropriate approach to address these challenges is the application of model-based control techniques. Within the paper an overview of mathematical models suitable for control purposes, a simple to implement load forecasting method as well as control strate-gies for both the individual components and the entire system are presented. Future chal-lenges for a practical implementation of this novel approach are discussed in the outlook sec-tion.

Polyhydroxyalkanoates (PHA) are a promising bio-based alternative to traditional plastics derived from petroleum. Cyanobacteria are photosynthetic organisms that produce PHA from CO2 and sunlight, which can potentially reduce production costs and environmental footprint in comparison to heterotrophic bacteria cultures because (1) they utilize inorganic carbon sources for growth and (2) they do not require intensive aeration for oxygenation. Moreover, supplementing precursors such as propionate, acetate, valerate, etc., can be used to obtain various copolymers with plastic customizable properties in comparison to the classical homopolymers, such as polyhydroxybutyrate, PHB. This critical review covers the latest advances in PHA production, including recent discoveries in the metabolism interplay between PHA and glycogen production, and new insights into cultivation strategies that enhance PHA accumulation, and purification processes. This review also addresses the challenges and suggests potential solutions for a viable industrial PHAs production process.

This publication deals with the characterisation of Jatropha curcas seeds and the oil obtained hereof. The analyzed seeds have been harvested from hedges and plantations in the regions of Teriya Bugu and Bla in Mali in the years 2009 and 2010. The oil is obtained through solvent extraction. Parameters analyzed are those which are relevant for processing of the oil into fatty acid methyl ester (FAME, biodiesel), and include acid value, fatty acid profile and contents of S, P, K, Na, Ca and Mg. All oil samples are suitable for processing into biodiesel, but some of them require pre-treatment because of high contents of free fatty acids and phosphorous. The margin of deviation of acid value and element contents throughout the oil samples depends on the way of cultivation, harvest and storage of the Jatropha curcas plants and seeds. Despite high acid values, all oil samples show high oxidation stability. © 2012 Elsevier Ltd.

This study presents combustion behavior and emission results obtained for different fuels: poultry litter (PL) and its char (PLC), scrap tires (ST) and its char (STC) and blends of char/lignite (PLC/LIG and STC/LIG). The combustion parameters and emissions were investigated via a non-isothermal thermogravimetric method and experiments in a lab-scale reactor. Fuel indexes were used for the prediction of high temperature corrosion risks and slagging potentials of the fuels used. The addition of chars to lignite caused a lowering of the combustion reactivity (anti-synergistic effect). There was a linear correlation between the NO_x emissions and the N content of the fuel. The form of S and the concentrations of alkali metals in the fuel had a strong effect on the extent of SO₂ emissions. The use of PL and PLC in blends reduced SO₂ emissions and sulphur compounds in the fly ash. The 2S/Cl ratio in the fuel showed that only PLC and STC/PLC would show a risk of corrosion during combustion. The ratio of basic to acidic oxides in fuel indicated that ST, STC and STC/LIG have low slagging potential. The molar (Si + P + K)/(Ca + Mg) ratio, which was used for PL, PLC and PLC containing blends, showed that the ash melting temperatures of these fuels would be higher than 1000 °C.

As the iron and steel industry needs to cut its CO2 emissions drastically, much effort has been put into establishing new—less greenhouse-gas-intensive—production lines fueled by hydrogen and electricity. Blast furnaces, as a central element of hot iron production, are expected to lose importance, at least in European production strategies. Yet, blast furnaces could play a significant role in the transitional phase, as they allow for the implementation of another CO2-reducing fuel, carbonized wood reducing agents, as a substitute for coal in auxiliary injection systems, which are currently widely used. Wood carbonization yields vastly differing fuel types depending on the severity of the treatment process, mainly its peak temperature. The goal of this study is to define the lowest treatment temperature, i.e., torrefaction temperature, which results in a biogenic reducing agent readily employable in existing coal injection systems, focusing on their conveying properties. Samples of different treatment temperatures ranging from 285 to 340 °C were produced and compared to injection coal regarding their chemical and mechanical properties. The critical conveyability in a standard dense-phase pneumatic conveying system was demonstrated with a sample of pilot-scale high-temperature torrefaction.

Biochars produced from pelletized grape vine (GV) and sunflower husk (SFH) agricultural residues were studied by pyrolysis in a batch reactor at 400 and 500 °C. Chemical and physical evolution of the biomass under pyrolysis conditions was determined and the products were characterized, including the main gaseous organic components. Results showed a decrease in solid biochar yield with increasing temperature. Biochar is defined as a “porous carbonaceous solid” produced by thermochemical conversion of organic materials in an oxygen depleted atmosphere, which has physiochemical properties suitable for the safe and long-term storage of carbon in the environment and, potentially, soil improvement. The aim of this work is to improve the knowledge and acceptability of alternative use of the biochar gained from agro-forestry biomass residuals, such as grape vine and sunflower husks, by means of modern chemical and physical characterization tools.

Over the last decades the general interest in recycling and upcycling technologies heavily grew and in the agricultural sector, it is not different. Lal estimated already in 2005 that 3,8 billion tons of crop residues alone are produced annually
worldwide.

With respect to the climate objectives Chemical Looping (CL) processes constitute a promising alternative to traditional thermochemical conversion routes. Through the application of solid materials, so-called oxygen carriers (OC), instead of air as oxygen supply, CO2 can be easily separated from the flue gas. By this, biomass can be used for hydrogen production (Chemical Looping Hydrogen, CLH) or it can be burnt without CO2 emissions (Chemical Looping Combustion, CLC).

Reliable experimental data and models are required to better understand and design chemical looping processes with oxygen carrier materials like ilmenite. A dubious variability of suggested kinetics for similar oxygen carrier materials has been presented in the literature. Part I of this work focuses on thermogravimetric analysis (TGA) of gas–solid kinetics and addresses several of its challenges, which are possible reasons behind such deviations. The reduction of synthetic ilmenite (60 mass% Fe2O3 ＋40 mass% TiO2) powder with H2 in a TGA system was investigated for this purpose.
Multiple steps were necessary to overcome mass transfer limitations during the measurements: (i) small sample masses down to 1.6 mg, (ii) high gas flow rates, (iii) a suitable sample carrier and (iv) proper sample dispersion on the sample carrier. Three types of sample carriers (crucible, basket and plate) were tested; the plate showed the best performance overall. It was alarming that an exemplary increase in sample mass from 1.6 to 3 mg, which was still significantly lower than all other studies reviewed, already introduced a noticeable influence of diffusion. Isothermal (650–950 °C, 17–50 vol% H2) and nonisothermal parameter studies were conducted and yielded vastly different isoconversional activation energies. A computational fluid dynamics (CFD) study of the TGA system suggested considerable axial dispersion of H2 influencing the initial conversion period.
These findings help to assess the reliability of kinetic studies and guide towards diffusion-free, kinetic measurements. The results will be used for model development in part II.

This work investigates the chemical looping combustion (CLC) and chemical looping hydrogen (CLH) production processes of synthetic ilmenite at three relevant length scales: reactor, particle and reaction. Focusing on reduction with hydrogen, part I analyzed the reaction scale for CLC using thermogravimetric analysis (TGA). Complementary fixed bed reactor experiments for reduction and oxidation using pellets (CLC, CLH) and TGA experiments using powders or pellets (CLH) were now added. All measurements were used to develop a consistent multiscale model. Particle and reactor scales were described by one-dimensional volumetric models. The required complexity of the reaction model differed from case to case. Kinetic modeling for oxidations in the reactor was trivial, since gaseous reactants were fully consumed. Reductions with hydrogen, however, were more intricate. Considering the influence of equilibrium on the reactivity was crucial for CLH. The reduction for CLC was faster and even more complex. We novelly demonstrated how kinetics, originally derived only from TGA with powders, were not directly applicable to larger scales when underlying phenomena had been neglected. In order to overcome these limitations and achieve better consistency, equilibrium effects and the gas availability above the sample during TGA had to be considered. The suitability of the synthetic ilmenite for CLC and CLH was discussed based on the findings in this work.

This work investigates the chemical looping combustion (CLC) and chemical looping hydrogen (CLH) production processes of synthetic ilmenite at three relevant length scales: reactor, particle and reaction. Focusing on reduction with hydrogen, part I analyzed the reaction scale for CLC using thermogravimetric analysis (TGA). Complementary fixed bed reactor experiments for reduction and oxidation using pellets (CLC, CLH) and TGA experiments using powders or pellets (CLH) were now added. All measurements were used to develop a consistent multiscale model. Particle and reactor scales were described by one-dimensional volumetric models. The required complexity of the reaction model differed from case to case. Kinetic modeling for oxidations in the reactor was trivial, since gaseous reactants were fully consumed. Reductions with hydrogen, however, were more intricate. Considering the influence of equilibrium on the reactivity was crucial for CLH. The reduction for CLC was faster and even more complex. We novelly demonstrated how kinetics, originally derived only from TGA with powders, were not directly applicable to larger scales when underlying phenomena had been neglected. In order to overcome these limitations and achieve better consistency, equilibrium effects and the gas availability above the sample during TGA had to be considered. The suitability of the synthetic ilmenite for CLC and CLH was discussed based on the findings in this work.

Industrial waste streams from brewing industries and distilleries provide a valuable but largely unused alternative substrate for biogas production by anaerobic digestion. High sulfur loads in the feed caused by acidic pretreatment to enhance bioavailability are responsible for H₂S formation during anaerobic digestion. Microbiological oxidation of H₂S provides an elegant technique to remove this toxic gas compound. Moreover, it allows for recovery of sulfuric acid, the final product of aerobic sulfide oxidation, as demonstrated in this study. Two-stage anaerobic digestion of brewer’s spent grains, the major byproduct in the brewing industry, allows for the release of up to 78% of total H₂S formed in the first pre-acidification stage. Desulfurization of such pre-acidification gas in continuous acidic biofiltration with immobilized sulfur-oxidizing bacteria resulted in a maximum H₂S elimination capacity of 473 g m^–3 h^–1 at an empty bed retention time of 91 s. Complete H₂S removal was achieved at inlet concentrations of up to 6363 ppm. The process was shown to be very robust, and even after an interruption of H₂S feeding for 10 days, excellent removal efficiency was immediately restored. A maximum sulfate production rate of 0.14 g L^–1 h^–1 was achieved, and a peak concentration of 4.18 g/L sulfuric acid was reached. Further experiments addressed the reduction of fresh water and chemicals to minimize process expenses. It was proven that up to 50% of mineral medium that is required in large amounts during microbiological desulfurization can be replaced by the liquid fraction of the digestate. The conducted study demonstrates the viability of microbial sulfur recovery with theoretical recovery rates of up to 44%.

In this paper the energy and carbon footprints of pellet imports from Australia, West Canada, and Russia for co-firing in Europe are investigated. Their ecologic and economic performances are proven by applying the Belgian and UK co-firing subsidy systems, which require dedicated sustainability evaluations. Based on the modelling of different subsidy schemes and price scenarios, the present paper identifies favourable conditions for the use of biomass co-firing in Germany and Austria, which currently do not have dedicated co-firing incentives. The present paper shows that under present conditions, co-firing has a narrow financial gap to coal with -3 to 4€ Cent/kWh_el and has low CO₂ mitigation costs compared to other renewables. Moreover, it is shown that co-firing is one of the most cost-attractive options to reach the EU-2020 targets. For policy makers, the support of co-firing is found to be very efficient in terms of cost-benefit ratio. It is proven that the co-firing subsidy schemes might direct supply chain decisions towards options with low energy and carbon impacts. © 2013 Elsevier Ltd.
 

Co-gasification of biomass and plastics was investigated in a 100 kW dual fluidized-bed pilot plant using four types of plastic material of different origins and soft wood pellets. The proportion of plastics was varied within a broad range to assess the interaction of the materials. The product gas composition was considerably influenced by co-gasification, whereas the changes were nonlinear. More CO and CO₂ were measured in the product gas from co-gasification than would be expected from linear interpolation of mono-gasification of the materials. Less CH₄ and C₂H ₄ were formed, and the tar content in the product gas was considerably lower than presumed. With the generation of more product gas than expected, co-gasification of wood and plastic materials also had other beneficial effects. Because of the fuel mixtures, more radicals of different types were available that interacted with each other and with the fluidization steam, enhancing the reforming reactions. Wood char had a positive effect on polymer decomposition, steam reforming, and tar reduction. As a result of the more active splash zone during co-gasification of wood and plastics, contact between gas and bed material was enhanced, which is crucial for catalytic tar removal. © 2013 American Chemical Society.

The continuous increase of (volatile) renewable energy production and the development of energy-efficient buildings have led to a transformation of city districts’ energy systems. Their complexity has increased significantly due to the coupling of the different energy sectors like heating, cooling and electricity. Such complex multi-energy systems can be operated more efficiently and reliably if knowledge of their specific components (in terms of mathematical models) as well as knowledge of weather forecasts is incorporated in a high-level controller, which is typically referred to as an Energy Management System (EMS). However, still little comprehensive information on the costs and the practical advantages of such systems is available. For this reason, a simulation environment to estimate the real costs and advantages of the use of such an EMS is required. Consequently, this work focuses on the development of an EMS for future city districts’ energy systems and the development of a co-simulation environment in order to demonstrate the benefits of the use of the developed EMS in comparison to a conventional control strategy. The co-simulation is implemented with the aid of the co-simulation platform Building Controls Virtual Test Bed (BCVTB) and consists of the following parts: a non-linear, thermoelectric model and a control block containing either the conventional control strategy or the EMS. The thermoelectric model is built up using the well-established simulation tools TRNSYS and IDA-ICE, simulating the energy hub of the city district and the districts’ buildings, respectively. The control block is simulated using MATLAB, where IBM ILOG CPLEX is used for solving the resulting mixed-integer linear program (MILP) of the EMS. Finally, an economic model for financial (and ecological) assessment of the operation is simulated with the aid of the software package Dymola. To put the developed EMS and the co-simulation into practise a case study based on a new city district in Graz, Austria, which is currently in the planning stage, is carried out. The integration of the responsible planners and investors in the modelling process guarantees the models’ practical applicability. In the case study the performance of the originally planned conventional control strategy is compared with the performance of the developed EMS using annual simulations with a simulation time step of 1 minute, and a 24 hour prediction horizon and a 15 minute time step for the EMS. For a more robust and realistic comparison both control strategies are simulated for different scenarios considering current and future (2060) climate conditions, medium and high energy demands (load), ideal and real load prediction methods and varying import prices for electricity from the electricity grid. The results show that the use of the developed EMS strategy results in reduced annual total costs (considering operational and investment costs of additionally suggested distributed energy resources) in comparison to the conventional control strategy. Furthermore, the annual CO2-emissions could be reduced by increasing the self-consumption of the installed (renewable) energy resources and thus decreasing the necessary energy imports from the electricity and the heating grid.

Slides of the talk "Co-Simulation of an Energy Management System for Future City District Energy Systems"

The CO/CO₂ release ratio obtained during char combustion of single biomass particles has been analysed in this work experimentally and by modelling. Experiments have been conducted with spruce, straw and Miscanthus pellets at different temperatures. Furthermore, these experiments have been modelled with a single particle model coupled with a CFD model of the single particle reactor. The results show that the CO/CO₂ ratio strongly depends on the feedstock, being lower for spruce than for straw or Miscanthus. Furthermore, the most commonly employed correlations for this ratio in literature are not adequate, as they either under- or over-predict it.

Chemical looping combustion has the potential to be an efficient and low-cost technology capable of contributing to the reduction of the atmospheric concentration of CO2 in order to reach the 1.5/2 °C goal and mitigate climate change. In this process, a metal oxide is used as oxygen carrier in a dual fluidized bed to generate clean CO2 via combustion of biomass. Most commonly, natural ores or synthetic materials are used as oxygen carrier whereas both must meet special requirements for the conversion of solid fuels. Synthetic oxygen carriers are characterized by higher reactivity at the expense of higher costs versus the lower-cost natural ores. To determine the viability of both possibilities, a techno-economic comparison of a synthetic material based on manganese, iron, and copper to the natural ore ilmenite was conducted. The synthetic oxygen carrier was characterized and tested in a pilot plant, where high combustion efficiencies up to 98.4% and carbon capture rates up to 98.5% were reached. The techno-economic assessment resulted in CO2 capture costs of 75 and 40 €/tCO2 for the synthetic and natural ore route respectively, whereas a sensitivity analysis showed the high impact of production costs and attrition rates of the synthetic material. The synthetic oxygen carrier could break even with the natural ore in case of lower production costs and attrition rates, which could be reached by adapting the production process and recycling material. By comparison to state-of-the-art technologies, it is demonstrated that both routes are viable and the capture cost of CO2 could be reduced by implementing the chemical looping combustion technology.

Dieser Bericht bietet eine ERhebung dero CO2e-Einsparungskosten außerhalb des ETS-Handels für den Bereich der Mobilität sowie der Wärmebereitstellung im häuslichen Sektor und Fern- und Nahwärme.

Der vorliegende Beitrag analysiert die Auswirkungen unterschiedlicher Brennstoffversorgungsszenarios im Calcinator des Zementherstellungsprozesses auf die emittierten CO2-Emissionen. In weiterer Folge werden die Grenzvermeidungskosten für CO2 im Vergleich zum Referenzszenario (100 % PetCoke) berechnet und dargestellt. Als alternative Brennstoffe werden auf Basis von Betriebserfahrungen sowie großtechnischer Versuche die alternativen Brennstoffe hochkalorischer Fluff (Standardszenario) sowie Schilf (Szenario A) und biogen angereicherter Ersatzbrennstoff (Szenario B) und vergleichend dazu in einer Literaturbasierten Analyse getrockneter Klärschlamm (Szenario C) betrachtet. Um die Auswirkung sich ändernder Marktbedingungen auf die Grenzvermeidungskosten abzubilden erfolgt eine Sensitivitätsanalyse hinsichtlich der Brennstoffgestehungskosten für die alternativen Brennstoffe sowie drei unterschiedliche Preisniveaus für Emissionsrechte und Brennstoffgestehungskosten des Referenzbrennstoffes PetCoke.

The dual fluidized bed (DFB) steam gasification technology of biomass was developed at Vienna University of Technology and is well-established for transforming biomass into a product gas which can be used for further applications. The DFB steam gasification reactor consists of a gasification chamber (bubbling bed, fluidized with steam) and a combustion chamber (turbulent bed, fluidized with air). Biomass is fed into the gasification chamber and gets in contact with the bed material, typically Olivine, at about 840°C. The released volatiles leave the gasification reactor as product gas. A part of the solid residue, called char, flows with the bed material via a chute to the combustion chamber where it is burnt with air. The bed material is heated up, separated from the flue gas stream in a cyclone and flows back to the gasification reactor via a loop seal where it provides the heat for devolatilization and drying of the biomass. The movement of the char is crucial since a sufficient amount has to flow to the combustion chamber and burn to provide enough energy for bed material heat-up. Up to now little is known about the char concentration in the bed material recirculation stream (or short recirculation stream) and its influencing variables. Therefore, a cold flow model, operated with ambient air, was constructed to study the influence of various parameters on the char concentration in the recirculation stream. Bronze is used as bed material since is matches closest to the scaling criteria. The char is also scaled; polyethylene is used as model char.

The cold flow model, see Figure 1 for the flowsheet, consists of a “gasification chamber” which corresponds to the gasification chamber in the hot plant and is as well operated as a bubbling bed. Via a chute the recirculation stream moves to a rotary valve which enables to set a fixed recirculation rate and make it independent from the following pneumatic conveying. Then, gas and solids are separated in a cyclone and the recirculation stream finally flows back to the gasification chamber. After the loop seal samples are taken for investigation of the model char concentration in the recirculation stream. In the present study the influence of fluidization rate in the gasification chamber, bed material recirculation rate and model char mass in the system on the char concentration in the recirculation stream are investigated. It was found that the model char particles show a flotsam behavior. Higher fluidization rates increase the model char concentration in the recirculation stream because of better mixing, whereas the bed material recirculation rate has only little influence. Doubling and tripling the overall char mass in the system did not lead to a doubling or tripling model char concentration in the recirculation stream. The present observations are helping to better understand the ongoing phenomena inside of the dual fluidized bed gasification reactor and provide knowledge to further optimize it.

A deeper understanding and quantification on the influence of inorganic species on the pyrolysis process, combined with the presence of heterogeneous secondary reactions, is pursued in this study. Both chemical controlled and transport limited regimes are considered. The former is achieved in a thermogravimetric analyser (TGA) with fine milled biomass in the mg range, while the latter is investigated in a particle level reactor with spherical particles of different sizes. To account for the influence of inorganics, wood particles were washed and doped with KCl aqueous solutions, resulting in K concentrations in the final wood of around 0.5% and 5% on dry basis. Gas species and condensable volatiles were measured online with Fourier transform infrared (FTIR) spectroscopy and a non-dispersive infrared (NDIR) gas analyzer. The removal of inorganic species delayed the pyrolysis reaction to higher temperatures and lowered char yields. The addition of inorganics (K) shifted the devolatilization process to lower temperatures, increased char and water yields, and reduced CO production among others. Higher heating rates and temperatures resulted in lower char, water, and light condensable yields, but significantly higher CH4 and other light hydrocarbons, as well as CO. The increase in these yields can be attributed, at least in part, to the gas phase cracking reactions of the produced volatiles. Larger particle size increased the formation of char, CH4 and other light hydrocarbons, and light condensables for low and high pyrolysis temperatures, while reduced the release of CO2 and H2O. This novel data set allows to quantify the influence of each parameter and can be used as basis for the development of detailed pyrolysis models which can include both the influence of inorganics and transport limitations when coupled into particle models.

Experiments have been conducted in a batch fixed bed lab-scale reactor to investigate the combustion behaviour of three different biomass fuels, poultry litter (PL), blend of PL with wood chips (PL/WC) and softwood pellets (SP). Analysis of the data gathered after completion of the test runs, provided useful insights about the thermal decomposition behaviour of the fuels, the formation of N gaseous species, the release of ash forming elements and the estimation of aerosol emissions. It was observed that the N gaseous species are mainly produced during the devolatilisation phase. Hydrogen cyanide (HCN) was the predominant compound in the case of SP combustion, whereas ammonia (NH3) displayed the highest concentration during the combustion of PL and blend (PL/WC). With reference to ash forming elements, the release rates of potassium (K) and sodium (Na) range between 15–50% and 20–37% respectively, whereas the release rate of sulphur (S) falls between 54–92%. Chlorine (Cl) presents very high release rate for all tested fuels acquiring values greater than 85%, showing the volatile nature of the specific compound. The maximum potential of aerosol emissions was estimated based on the calculation of ash forming elements. In particular, during PL combustion the maximum aerosol emissions were observed, 2806 mg/Nm3 (dry flue gas, 13 vol% O2), mainly influenced by the release rate of K in the gas phase. Fuel indexes for the pre-evaluation of combustion related challenges such as NOx emissions, potential for aerosols formation, corrosion risk, and ash melting behaviour have also been investigated.

Various single particle models to describe the conversion of porous solids with gaseous reactants are available in the literature. It is, therefore, not obvious which models should be selected for specific problems and applications. This work focuses on two popular types of particle models: the volumetric model (VM) and the layer model (LM). Different variations of the layer model were considered: the standard layer model, which is similar to common shrinking core models, and an extended layer model, which solves inherent problems of the shrinking core approach by replacing surface reactions with volumetric reactions. For the first time, all these models were benchmarked together regarding prediction quality and computational cost for relevant applications: gasification and oxidation of biochar, reduction of nickel oxide and oxidation of magnetite. These cases covered a wide range of Thiele moduli and Biot numbers. The volumetric model reliably predicted the conversion for all cases considered. Its computational effort was, however, significantly higher than for the layer models. Suitable reactions kinetics in combination with heat of reaction and pore diameters were integral to prediction accuracy. Char oxidation, having a high Thiele modulus, could be described suitably by the standard layer model and the extended layer model, when it accounted for the residual ash layer. Char gasification and nickel oxide reduction had moderate Thiele moduli, rendering the standard layer model unsuitable in the general case. The extended layer model overcomes these limitations due to its volumetric reaction approach. All layer models showed inferior temperature predictions for biochar gasification and magnetite oxidation owing to their lower spatial resolution compared to the volumetric model. Additional, possible problems for layer models were addressed.

A better understanding of the underlying motives of consumers considering a new RESS (heating,
cooling and electricity) can contribute to create favorable conditions for an energy transition.
Therefore, the main objectives of this research project are to:
▪ Identify motives of consumers interested in ordeciding for a certain RESS
▪ Assess the impact of gender and intersectingaspects, such as age, income and education on these motives.

Combustion of waste wood can cause slagging, fouling and corrosion which lead to boiler failure, affecting the energy efficiency and the lifetime of the power plant. Additivation with mineral and sulfur containing additives during waste wood combustion could potentially reduce these problems. This study aims at understanding the environmental impacts of using additives to improve the operational performance of waste wood combustion. The environmental profiles of four energy plants (producing heat and/or power), located in different European countries (Poland, Austria, Sweden and Germany), were investigated through a consequential life cycle assessment (LCA). The four energy plants are all fueled by waste wood and/or residues. This analysis explored the influences of applying different additives strategies in the four power plants, different wood fuel mixes and resulting direct emissions, to the total life cycle environmental impacts of heat and power generated. The impacts on climate change, acidification, particulate matter, freshwater eutrophication, human toxicity and cumulative energy demand were calculated, considering 1 GJ of exergy as functional unit. Primary data for the operation without additives were collected from the power plant operators, and emission data for the additives scenarios were collected from onsite measurements. A sensitivity analysis was conducted on the expected increase of energy efficiency. The analysis indicated that the use of gypsum waste, halloysite and coal fly ash decreases the environmental impacts of heat and electricity produced (average of 12% decrease in all impacts studied, and a maximum decrease of 121%). The decrease of impacts is mainly a consequence of the increase of energy generation that avoids the use of more polluting marginal technologies. However, impacts on acidification may increase (up to 120% increase) under the absence of appropriate flue gas cleaning systems. Halloysite was the additive presenting the highest benefits.

A new model-based control strategy for biomass grate boilers is presented in this paper. Internal model control is used to control four outputs of the plant and to achieve a control structure with fewer control parameters needing to be experimentally tuned. A nonlinear state–space model describing the essential behaviour of the biomass grate boiler is used for controller design. The inverse system dynamics representing the main part of internal model control are designed with the help of this model. In doing so the properties of differentially flat systems are used. Due to a time delayed input, the inverse system is determined only for three input output channels. The stabilization of the inverse system dynamics, however, is a challenging task. A stabilization method with the help of the time delayed input is suggested and a stability analysis is given. The new control strategy has only three parameters to be tuned, representing a major reduction of complexity in comparison to existing model-based approaches. Finally, experimental results of the implemented control strategy on representative biomass grate boiler with a nominal capacity of 180 kW are presented and compared to an existing model-based control strategy based on input output linearization. The experimental evaluation proves that it is possible to operate the biomass boiler in all load ranges with high efficiency and low pollutant emissions.

Overview on different approaches for the control of the heat distribution networks in case of the integration of large-scale solar thermal systems, and different possibilities for the reduction of the operating temperatures in DH systems.

Overview on the control of large-scale thermal plants, limited to plants feeding into DH networks as well as theirkey components, i.e. the actual collector circuit and the heat exchanger between primary and secondary circuit.

Absorption heat pumping devices (AHPDs, comprising absorption heat pumps and chillers) are devices that use thermal energy instead of electricity to generate heating and cooling, thereby facilitating the use of waste heat and renewable energy sources such as solar or geothermal energy. Despite this benefit, widespread use of AHPDs is still limited. One reason for this is partly unsatisfactory control performance under varying operating conditions, which can result in poor modulation and part load capability. A promising approach to tackle this issue is using dynamic, model-based control strategies, whose effectiveness, however, strongly depend on the model being used. This paper therefore focuses on the derivation of a viable dynamic model to be used for such model-based control strategies for AHPDs such as state feedback or model-predictive control. The derived model is experimentally validated, showing good modeling accuracy. Its modeling accuracy is also compared to alternative model versions, that contain other heat transfer correlations, as a benchmark. Although the derived model is mathematically simple, it does have the structure of a nonlinear differential–algebraic system of equations. To obtain an even simpler model structure, linearization at an operating point is discussed to derive a model in linear state space representation. The experimental validation shows that the linear model does have slightly worse steady-state accuracy, but that the dynamic accuracy seems to be almost unaffected by the linearization. The presented new modeling approach is considered suitable to be used as a basis for the design of advanced, model-based control strategies, ultimately aiming to improve the modulation and part load capability of AHPDs.

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

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

The authors want to acknowledge, that during the production of the final version of the publication the image for Figure 9 has been replaced with the image for Figure 12, however without changing the content of the paper. This issue is resolved in the current version of the publication.

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

The major problem of fluidized bed biomass gasification is the high tar contamination of the producer gas which is associated with the complex and time-consuming sampling and analysis of these tars. Therefore, correlations to predict the tar content are a helpful tool for the development and operation of biomass gasifiers. Correlations between tars and gas composition as well as reactor temperature derived for a steam-blown lab-scale bubbling fluidized bed gasifier are investigated in this study to assess their applicability. A comprehensive data set containing over 80 experimental points was obtained for various operation conditions, including variations in temperature from 700 to 800 °C, feedstock, amount of steam for fluidization, as well as the addition of oxygen. Linear correlations between tar and permanent gases show good accuracy for H2 and CH4 when using pure steam. However, experiments conducted with steam-oxygen mixtures show high deviations for the CH4-based correlation and smaller but still significant deviations for the H2-based correlation. No relation between tar and CO or CO2 was found. The correlation between tar and temperature shows highest accuracy, including good agreement with the steam-oxygen experiments. All tar correlations showed useful results over a broad operating range. However, significant deviations can be obtained when considering just one gas compound. Therefore, a combination of different correlations considering gas components and temperature seems to be the best method of tar prediction. This leads to a powerful tool for fast online tar monitoring for a broad range of operating conditions, once a calibration measurement was conducted.

The aim of the current study was to investigate the feasibility of membrane contactors for continuous ammonia (NH₃-N) removal in an anaerobic digestion process and to counteract ammonia inhibition. Two laboratory anaerobic digesters were fed slaughterhouse wastes with ammonium (NH₄⁺) concentrations ranging from 6 to 7.4 g/L. One reactor was used as reference reactor without any ammonia removal. In the second reactor, a hollow fiber membrane contactor module was used for continuous ammonia removal. The hollow fiber membranes were directly submerged into the digestate of the anaerobic reactor. Sulfuric acid was circulated in the lumen as an adsorbent solution. Using this set up, the NH₄⁺-N concentration in the membrane reactor was significantly reduced. Moreover the extraction of ammonia lowered the pH by 0.2 units. In combination that led to a lowering of the free NH₃-N concentration by about 70%. Ammonia inhibition in the reference reactor was observed when the concentration exceeded 6 g/L NH₄⁺-N or 1-1.2 g/L NH₃-N. In contrast, in the membrane reactor the volatile fatty acid concentration, an indicator for process stability, was much lower and a higher gas yield and better degradation was observed. The chosen approach offers an appealing technology to remove ammonia directly from media having high concentrations of solids and it can help to improve process efficiency in anaerobic digestion of ammonia rich substrates. © 2012 Elsevier Ltd.

The present work was carried out to simulate a cold flow model of a biomass gasification plant. For the simulation, a Eulerian-Lagrangian approach, more specifically the multi-phase particle in cell (MP-PIC) method, was used to simulate particles with a defined particle size distribution. Therefore, Barracuda VR, a software tool with an implemented MP-PIC method specifically designed for computational particle fluid dynamics simulations, was the software of choice. The simulation results were verified with data from previous experiments conducted on a physical cold flow model. The cold flow model was operated with air and bronze particles. The simulations were conducted with different drag laws: an energy-minimization multi-scale (EMMS) approach, a blended Wen-Yu and Ergun drag law, and a drag law of Ganser. The fluid dynamic behavior depends heavily on the particles’ properties like the particle size distribution. Furthermore, a focus was placed on the normal particle stress (P_S value variation), which is significant in close-packed regions, and the loop seals’ fluidization rate was varied to influence the particle circulation rate. The settings of the simulation were optimized, flooding behavior did not occur in advanced simulations, and the simulations reached a stable steady state behavior. The Ganser drag law combined with an adjusted P_S value with (P_S = 30 Pa) or without (P_S = 50 Pa) increased loop seal fluidization rates provided the best simulation results.

Dual fluidized bed (DFB) systems for biomass gasification consist of two connected fluidized beds with a circulating bed material in between. Inside such reactor systems, rough conditions occur due to the high temperatures and the movement of the bed material. Computational fluid dynamics calculations are a useful tool for investigating fluid dynamics inside such a reactor system. In this study, an industrial-sized DFB system was simulated with the commercial code CPFD Barracuda. The DFB system is part of the combined heat and power (CHP) plant at Güssing, situated in Austria, and has a total fuel input of 8 MW_th. The model was set up according to geometry and operating data which allows a realistic description of the hot system in the simulation environment. Furthermore, a conversion model for the biomass particles was implemented which covers the drying and devolatilization processes. Homogeneous and heterogeneous reactions were considered. Since drag models have an important influence on fluidization behavior, four drag models were tested. It was found that the EMMS drag model fits best, with an error of below 20%, whereas the other drag models produced much larger errors. Based on this drag law, further simulations were conducted. The simulation model correctly predicts the different fluidization regimes and pressure drops in the reactor system. It is also able to predict the compositions of the product and flue gas, as well as the temperatures inside the reactor, with reasonable accuracy. Due to the results obtained, Barracuda seems suitable for further investigations regarding the fluid mechanics of such reactors.

Microalgal biomass as a feedstock for biogas production is linked to the parameters biomass productivity and biogas yield. Besides an easy-to-use strain for anaerobic digestion, the photobioreactor (PBR) design is important. A microalgae strain selection revealed Eustigmatos magnus (SAG 36.89) as the most promising strain yielding an average of 100 mg total suspended solids (TSS) L−1 day−1. The strain was tested in cost-effective sleevebag-PBR-systems of 10 cm, 20 cm and 30 cm diameter facing the light from the front or laterally. Highest mean productivity on a volumetric basis was measured in PBRs with the lowest diameter (104 and 117 mg L−1 day−1. The highest productivity per m−2 was achieved in 10 cm PBRs with front light configuration (9.35 g TSS m−2 day−1). The lateral light configuration of 10 cm PBRs had positive aspects such as the lowest mean water demand to produce 1 kg TSS (481 L−1 kg−1) and the lowest mean energy demand for medium separation of 1 kg TSS (106 Wh). The concentrated microalgal biomass was then subjected to ultrasonication and thermal pre-treatment (90 °C and 120 °C) and tested in BMP tests. Mesophilic anaerobic mono-digestion of untreated microalgae biomass led to a methane (CH4) yield of 343 L−1 kg−1 volatile solids (VS). Thermal pre-treatment at 120 °C resulted in significantly increased CH4 yields of 430 L−1 kg−1 VS. As thermal pre-treatment can be easily installed nearby a biogas plant it could be an interesting option for AD of microalgal biomass with only little investment.

The reduction of greenhouse gas emission is an important issue for steel industry. One possibility is to use biomass-based reducing agents, also called bioreducers, to replace a least partly the fossil reducer agents. To produce bioreducer we treated woody biomass in a lab-scale muffle furnace, we performed grinding experiments with a ball mill, we analyzed the particle size distribution with laser diffraction and we used a rotating device, the revolution powder analyzer, for flow behavior investigations. Our preliminary results show that treatment temperatures >250 oC bring adequate increased calorific value and improved grindability. For a certain treatment temperature the particle size distribution and as well the flow behavior shows similarities to lignite.

The reduction of greenhouse gas emissions is an important issue for iron and steel industry. One possibility is to use biomass-based reducing agents, also called bioreducers, to replace at least partly the fossil reducer agents. In a first step woody biomass was treated in a lab-scale muffle furnace and afterwards ground with a ball mill. The powder characteristics were investigated in respect to the flow behavior. For a certain treatment temperature the particle size distribution and as well the flow behavior shows similarities to lignite. The next stage was to identify relations between powder characteristics and its fluidization behavior. A fluidization device was assembled and used to determine the minimum fluidization gas velocity for various bioreducer powders.

Winter tourism is an energy-intensive branch of industry. The aim of the FFG funding project Clean Energy for Tourism is to support Salzburg’s skiing areas on the way to decarbonization by developing technologies and business models. In this article, the developed ICT infrastructure, the optimization algorithms and the business models are presented.

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.

Aqueous phase reforming (APR) describes the conversion of oxygenated hydrocarbons dissolved in
an aqueous phase to hydrogen and carbon dioxide.

Driven by increasing energy and raw material prices as well as changes in the legal framework the state of the art in the European Union has changed from waste management to resource management over the past 15 years. This has led to a higher appreciation of the resource “waste” as a secondary raw material as well as an energy resource. In this context the importance of effective waste processing in order to allow quality specific routing of waste streams has become very important. On the one hand material recycling requires a high purity of the waste material to be recycled. The prices to be achieved for the recycling material are highly dependend on the purity of the recyclables. The economic viability of treatment concepts very much depends on the rate of recovery of the recycling product. On the other hand the portion of waste that is thermally treated has increased and still is on the rise. Furthermore extensive efforts on the usage of waste fractions as Solid Recovered Fuels (SRF) in alternative thermal treatment processes with higher energy recovery are being undertaken. Alternative thermal treatment
processes have special demands on the quality of the waste streams to be treated due to process and product quality reasons as well as ecological concerns. Sophisticated waste pre-treatment concepts ensure compliance with required quality standards of wastes to be recycled or utilized energetically. In spite of that waste pre-treatment - in sometimes complex processes - the problem of disposal of the remaining residual waste fraction has to be solved, as the disposal of the residuals in compliance with the regulatory framework causes high expenses for the waste treatment plant operator. The first part of this manuscript focusses on the legal framework prompting the implementation of new waste processing technologies allowing an effective routing of waste fractions by material specific splitting of the over all waste stream. Most relevant in that respect are the EU Waste Framework Directive as well as the EU Landfill Directive and the EU Packaging Directive. Climate
policy and respective regulations are also influencing waste management practice. Additionally economic aspects for destination-process specific routing of waste streams are being addressed. In the second part of this manuscript the set-up of test runs as well as the results obtained and experiences gained based on the test runs are being reported. One test set-up aims at removing highcaloric waste components from waste streams of Mechanical-Biological Treatment (MBT) facilities in order to maximize the quantity of waste that can be landfilled. A second test set up deals with the processing of commercial plastic waste containing different types of polymers in order to gain pure recyclables. As the economic value of waste plastic depends on the purity in terms of individual polymers it is very important to separate individual polymers from mixed plastic waste. Near-Infrared
(NIR) sensor based sorting allows a separation of different types of plastics. The results of test runs are explained in terms of quality and yield of product gained as well as economical aspects. Although the prices for recyclables have fallen during the last months as a result of the financial and economical crisis leading to a decrease in the demand of recyclables it is assumed that gaining high quality waste fractions from mixed wastes for material recyling as well as energy recovery will become more important in the long run.