Emissions from wood-burning stoves contribute to local air pollution. However, it is difficult to determine the real emissions from such stoves, especially due to unknown user behaviour, which can have a large impact on emissions. In this study, the low-cost emission reduction measure “user training” was evaluated to determine its emission reduction potential on firewood stoves. Two sets of tests were carried out. First, a field measurement campaign was conducted in Styria (Austria) with four wood stoves, where gaseous and particulate emissions were measured before and after a user training on optimised heating behaviour (e.g. ignition mode, fuel properties and placement in the combustion chamber, air supply). Gaseous emissions (carbon monoxide – CO, organic gaseous compounds – OGC) were measured continuously, while particulates were measured in batches, in undiluted and hot as well as in diluted and cooled flue gas in parallel with a specific field measurement setup. In addition, particle filters were analysed to quantify the concentration of the carcinogenic compound benzo(a)pyrene (BaP). Second, user training workshops were conducted. These tests had a simple measurement setup in order to increase the number of tests. Thus, only CO emissions were evaluated.

The results show that real life emissions in the field are high and have a high variability compared to laboratory tests and official type test results. However, user training showed a significant reduction of CO, OGC, TSP and BaP emissions of 42%, 57%, 45% and 76% (median), respectively. In addition, TSPsum (sum of hot and cooled particle emission samples) emissions decreased by 39% (median) after user training. The relative reduction rates of all batches show that the highest emission reduction potential was identified for BaP, with a reduction rate of up to 97%. The results of the workshop tests confirmed the high variability in user behavior and the range for the emission reduction potentials, with a median CO reduction of 41%.

The emission reduction potential of the user training measure is comparable to state-of-the-art technological measures such as electrostatic precipitators and catalysts. However, these measures are costly and require a high level of technical sophistication. User training, on the other hand, is relatively cheap, easy to implement and suitable for all users. Of course, there is some risk that trained end-users will revert to their old habits, leading to higher emissions again. Therefore, regular training may be necessary to maintain the higher level of performance. As we did not assess this aspect in our work, further research would be needed to prove this theory.

Retrofitting buildings with predictive control strategies can reduce their energy demand and improve thermal comfort by considering their thermal inertia and future weather conditions. A key challenge is minimizing additional infrastructure, such as sensors and actuators, while ensuring user comfort at all times. This study focuses on retrofitting with intelligent software, incorporating the users’ feedback directly into the control loop. We propose a predictive control strategy using an optimization-based energy management system (EMS) to control thermal zones in an office building. It uses a physically motivated grey-box model to predict and adjust thermal demand, with individual zones modelled using an RC-approach and parameter estimation handled by an unscented Kalman filter (UKF). This reduces deployment effort as the parameters are learned from historical data. The objective function ensures user comfort, penalizes undesirable behaviour and minimizes heating and cooling costs. An internal comfort model, automatically calibrated with user feedback by another UKF, further improves system performance. The practical case study is an office building at the ”Innovation District Inffeld”. Operation of the system for one year yielded significant results compared to conventional control. Thermal comfort was improved by 12% and thermal energy consumption for heating and cooling was reduced by about 35%.

Pyrolyse ist ein althergebrachtes Verfahren, das bereits vor Jahrtausenden zur Herstellung von Kohle praktiziert wurde. Bestrebungen nach Unabhängigkeit von fossilen Ressourcen und klimaneutralen sowie kreislaufwirtschaftlichen Wertschöpfungsketten, führen aktuell zu deutlich steigendem Interesse an dieser Technologie. Durch vielseitige verfahrenstechnische Ausgestaltungsmöglichkeiten stellt die Pyrolyse eine potenzielle Schlüsseltechnologie für verschiedene zum Teil hoch spezifische Anwendungen für stoffliche und energetische Prozessketten dar. Diese Vielfalt an Möglichkeiten resultiert jedoch gleichzeitig in einer hohen Komplexität, die es erschwert einen Überblick über angebotene Anlagen zu bekommen.

Ziel dieser Studie ist es, Informationen vielfältiger Systeme in eine vergleichbare Form zu bringen und dadurch eine Übersicht für Interessierte zu ermöglichen. Der Aufwand der Informationsbeschaffung als initialer Schritt für Umsetzungen soll dadurch reduziert werden. Hierdurch soll zur Realisierung regionaler Pyrolyseprojekte als Bestandteil kreislaufwirtschaftlicher Stoffnutzungskonzepte beigetragen werden.

Phytoremediation is the use of vegetation for the in situ treatment of contaminated environments. After plants have been used for phytoremediation of soils, their biomass can be used for example as value-added products or converted by thermochemical processes. Large-scale application of pyrolysis technology for phytoremediation biomass requires accurate predictive kinetic models and a characterization of the toxicity of the materials produced. The pyrolysis of industrial hemp (Cannabis sativa L.) was investigated on a laboratory scale by varying the process conditions and accurately modelled by considering four pseudo-components with first reaction order. The average value of the coefficients of determination is 0.9980. Biomass and biochar were characterized and the main components of the gas phase were monitored. We found Cd, Pb, and Zn in the roots, although in lower amounts than in the soil. Especially the leaves and stems showed negligible traces of these elements, so that these parts can be used directly, even if the hemp was grown on the polluted soil. After pyrolysis, the concentration of pollutants in the solid fraction decreased, which could be attributed to the reduction of metal oxides (or salts) to elemental form and subsequent evaporation. This pyrolysis process has the potential to treat heavy metal-rich biomass, with gas phase purification via condensation, yielding agricultural-grade biochar, CO-rich gas and a highly concentrated heavy metal stream in absorbent material.

A dried dairy processing sludge (sludge from wastewater treatment of an effluent from a milk processing plant) was pyrolysed in a single-particle reactor at different temperatures from 400 °C to 900 °C. NH₃ and HCN were measured online and offline by means of FTIR as well as by cumulative sampling in impinger bottles (in 0.05 M H₂SO₄ and 1 M NaOH, respectively) and analysed by photometric method. NO and NO₂ were measured online using a nitric oxide analyser while N₂O was measured by FTIR. Nitrogen (N) in the sludge and in the remaining char, char-N, was determined. Moreover, tar content in pyrolysis gas was measured and tar-N was determined. The results with respect to N mass balance closure are discussed. The different measurements techniques are compared. For pyrolysis at 520 ℃ and 700 ℃ nitrogen in the gas phase was mainly contained as N₂ (36 % and 40 % respectively), followed by NH₃ (15 % and 18 %), tar-N (10 % and 9 %), HCN (1 % and 3 %), NO (1 %) and NO₂ (0.2 %). The dairy processing sludge has very specific properties with organic-N present predominantly as proteins and a high content of inherent Ca. These characteristics affected the distribution of N. The amount of char-N was higher while the amount of tar-N lower than for sewage sludge from literature, at comparable pyrolysis temperature.

First experiments with biogenic residues and a plastic-rich rejects and woody biomass blend were conducted in an advanced 1 MW dual fluidized bed steam gasification demonstration plant at the Syngas Platform Vienna. Wood chips, bark, forest residues, and the plastic-rich rejects and woody biomass blend were tested and the tar composition was analyzed upstream and downstream of the upper gasification reactor, which is designed as a high-temperature column with countercurrent flow of catalytic material. Each feedstock was gasified with olivine as bed material in demonstration scale and is compared to the gasification of softwood pellets with olivine and limestone in pilot scale. A reduction in tar content was observed after countercurrent column for all feedstocks. However, a shift in tar species occurred. While styrene, phenol, and 1H-indene were predominant upstream, naphthalene and polycyclic aromatic hydrocarbons (PAHs) were the prevailing tar species downstream the countercurrent column. Hence, an increase of i.e. anthracene, fluoranthene, and pyrene from the upstream concentration was observed. For pyrene, up to twice the initial concentration was measured. This recombination to PAHs was observed for all feedstocks in demonstration- and pilot-scale. The only exception occurred with limestone as bed material, characterized by a higher catalytic activity in comparison to the typically used olivine. In the perspective of the integrated product gas cleaning, tar with higher temperature of condensation are separated more efficiently in the installed scrubbing unit. Hence, the recombination facilitates an overall decline of tar content after the gas cleaning.

Sustainable liquid biofuels are fundamental for decarbonizing the transportation
sector. Biofuels offer a viable, economical, and environmentally sustainable alternative
to fossil fuels, serving as a bridge to future mobility solutions like electromobility and
hydrogen, which have longer development timelines. They improve air quality, public
health, and contribute to agricultural and economic development, enhancing energy
diversification, security, and leveraging each country's comparative advantages. The
main challenges for the continued development of biofuels are the absence of an
international standard, coordination and certification methodologies, lack of regulations
in some countries and the subsidies to fossil fuels. The authors of this policy brief
recommend that the G20 and the international community strengthen regulatory
frameworks for sustainable biofuel use in land transportation, standardize and harmonize
GHG reduction standards and certification mechanisms, and develop common regional
and national policies to advance the production and consumption of new biofuels for
sectors such as aviation and maritime transportation. An analysis1 of biofuels
implementation in emerging markets of Africa, Asia, and Latin America shows that
meeting 25% blending targets requires only 1–7.8% of their total land area, achieving
substantial GHG reductions. Favorable climatic conditions for biomass production in
these countries and the low greenhouse gas impact of international freight underscore the
benefits of global biofuel trade, highlighting the urgent need for widespread adoption to
accelerate decarbonization efforts.

The detailed ash transformation process during the combustion of agricultural biomass containing moderate to high amounts of P was studied in entrained flow conditions. The selected fuels were grass and brewer’s spent grain (BSG) containing a moderate and high amount of P in the fuel, respectively. The experiments were conducted in a lab-scale drop tube furnace at 1200 and 1450 °C. The residual chars, ashes, and particulate matter (PM) were collected and analyzed by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and ion chromatography (IC), and CHN-analysis. Additionally, the obtained results were interpreted through thermodynamic equilibrium calculations (TECs). For both fuels, P was primarily identified in the residual coarse ash (>1 μm) fractions. In contrast, a minor to moderate amount of fuel inherent P was detected in the fine particulate (<1 μm) fraction at 1200 and 1450 °C, respectively. For grass, the retained P in the residual coarse ash fractions was mainly identified as amorphous K–Ca–Mg-rich phosphosilicate melt. These phosphosilicates were most likely formed through the initial formation of molten K-rich silicates, with subsequent incorporation of Ca, P, and Mg. For BSG, a P–Si-rich fuel with moderate to minor amounts of Ca, Mg, and K, most P was retained in a Ca–Mg-rich phosphosilicate melt, likely originating from phytate-derived Ca–Mg phosphates interacting with fuel-inherent Si-rich particles. The results obtained from this study could be used to address the ash-related challenges and potential P-recovery routes during pulverized fuel combustion of P-containing biomass.

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.

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.

After years of development of the dual fluidized bed gasification process with woody biomass, new challenges arise with a wider range of feedstocks, such as agricultural residues or waste fractions, gaining importance. This work presents the results from the operation of a 1 MW advanced dual fluidized bed (aDFB) gasifier at the Syngas Platform Vienna, with cashew shells (CS) as feedstock and pure olivine or olivine mixed with 33% limestone as the bed material. Two operation points, different in their main process parameters, with CS as feedstock were performed for a minimum of 16 h. Due to the high calorific value (22.7 MJ/kg dry) and high content of volatile components (81.7 wt % dry), CS are well suited for gasification. During the operation, a product gas with a H2/CO ratio of 1.93–2.29 was produced, which suits the use of the syngas as input for Fischer–Tropsch synthesis. Due to the low ash softening temperature of CS of about 840 °C, determined in ash fusion tests and predicted by thermodynamic equilibrium calculations, the operating temperature in the gasifier was kept below 820 °C in the first operation point with around 20 h of runtime. Bed material samples after the operation revealed the formation of agglomerates, which were analyzed by SEM and EDS for their morphology and composition. During the second operation point, temperatures in the gasifier were increased to 870 °C for 16 h, while no agglomeration tendencies were observed. Both operations did not show changes in fluidization behavior compared to operations with wood chips (WC). The evaluated key performance indicators were compared to aDFB steam gasification of WC as the reference.

This study explores AnMBR technology as a promising method for treating wastewater from the meat-processing industry by analysing its characteristics and impact under continuous feeding. The solids were retained, utilising an ultrafiltration membrane with a pore size of 0.2 µm, and the efficacy of reducing the organic load was evaluated. Although the COD removal rate decreased from 100% at an OLR of 0.71 g/(L*d) to 73% at an OLR of 2.2 g/(L*d), maximum methane yields were achieved at the highest OLR, 292.9 Nm3/t (COD) and 397.8 Nm3/t (VS) per loaded organics and 353.1 Nm3/t (COD) and 518.7 Nm3/t (VS) per removed organics. An analysis of the microbial community was performed at the end of the experiment to assess the effects of the process and the substrate on its composition. The AnMBR system effectively converts meat-processing wastewater into biogas, maintaining high yields and reducing the loss of dissolved methane in the permeate, thanks to a temperature of 37 °C and high salt levels. AnMBR enables rapid start-up, efficient COD removal, and high biogas yields, making it suitable for treating industrial wastewater with high organic loads, enhancing biogas production, and reducing methane loss. Challenges such as high salt and phosphate levels present opportunities for a wider use in nutrient recovery and water reclamation.

Aqueous phase reforming (APR) has been proposed during the last years as a promising technology to produce renewable hydrogen from carbon-laden water fractions. However, only small-scale set-ups have been used for the investigation so far, leading to a gap in technological knowledge. In this work, a multi-component mixture representative of wastewater from lignin-rich hydrothermal liquefaction (HTL) was evaluated at two different scales: a lab-scale facility (30–60 mL/h) to optimize the reaction conditions and, for the first time, a pilot-scale unit (max. 44 L/h) to validate the results. On lab scale, the influence of reaction temperature, weight hourly space velocity and feed concentration on the process performance was investigated using a response surface methodology (RSM) approach via Box-Behnken design. It was found out that temperature was the most important variable to model the reactants conversion, carbon conversion to gas and hydrogen yield, with a significant agreement between the experimental and predicted values in the design space. At pilot scale, the influence of temperature and pressure as well as catalyst stability were investigated. Furthermore, stable operation was demonstrated in a continuous 100 h experiment. A maximum hydrogen yield of 58% and carbon conversion to gas of 54% were achieved at 547 K, 10 g/L organics concentration and 60 mL/gcat‧h. Overall, this study allowed to increase the understanding of APR at the highest technology readiness level available so far, paving the way towards its implementation on industrial scale.

The advanced dual fluidized bed steam gasification technology allows the generation of a medium-calorific product gas from various feedstocks. Thereby, biogenic residues, municipal and industrial wastes e.g., sewage sludge or rejects from pulp and paper industry can be utilised. This paper presents the development step of this technology from pilot to demonstration plant scale i.e. the step from technology readiness level 4 to 6. The newly erected demonstration plant at the Syngas Platform Vienna is designed for 1 MWth fuel input power and incorporates a counter current column as the upper part of the gasification. This design choice already resulted in an improvement of product gas quality in pilot scale. By comparing the data gathered from multiple years of 100 kWth pilot scale testing at TU Wien with first results from the new demonstration plant via mass and energy balance simulation, fluidisation regimes and temperature and pressure profiles, the success of the scale-up of the reactor design is proven. The first full load operation achieved a conversion of 1 MW fuel input power into 769 kW product gas power. This translates to 256 kg/h dry biomass being converted into 245 Nm3/h of dry product gas. Although first experiments with the reference feedstock high-grade wood chips showed good reproducibility of the results achieved in pilot scale, challenges still remain. The expected product gas composition was different compared to pilot scale results, as the volume share of hydrogen was lower and the relative content of carbon monoxide and carbon dioxide inverted. While the results show an important intermediate step in the process development, the challenges of improving product gas quality and increasing overall conversion efficiency remain to be tackled.