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The aim of this work is to evaluate the performance of a reforming-unit for the treatment of syngas and char produced in an air gasifier. This approach represents an alternative option to produce hydrogen-rich syngas from air gasification. The reformer reactor was operated under a range of temperatures and at different steam flows and for each operating condition the changes and improvements in producer gas composition were measured. The results highlight that in the absence of char and steam no substantial changes are measured in the producer gas composition, while in the absence of char but with a steam flow or in the absence of steam but with a char-bed a maximum hydrogen concentration increase +31 % can be obtained at higher temperatures. On the other hand, the combined effect of char and steam significantly improves the hydrogen concentration of approx. +194 % at 800 °C with the highest steam flow tested. These results provide a guide for future optimization studies into the enhancement of gas quality in air gasification systems., Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 790-793

In this study, we propose an integrated process to valorize the residual wet streams from food processing industries and their high water content considering apple pomace as the model substrate. The process consists in three combined steps: subcritical water pretreatment (SubH2O), hydrothermal carbonization (HTC) of the pretreated solid fraction and anaerobic digestion (AD) of the pretreated liquid fraction combined with the HTC solid product (i.e., hydrochar). Both SubH2O and HTC were run in series in the same vessel, a 250 mL pressurized batch reactor equipped with one thermocouple and a pressure transducer. The SubH2O step was optimized using robust parameter design to assess the most effective factors affecting the treatment (temperature, pressure, and biomass-to-water ratio). According to the preliminary results, subcritical water deconstructs the apple pomace matrix, solubilizing the organic compounds and increasing the percentage of volatiles. Such increase is the consequence of the enhanced reactivity of the substrate, which is now more likely to be treated. Moreover, it is expected that adding the hydrochar from HTC to the AD process will improve the biogas quality in terms of methane concentration per unit of volume., Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 911-913

This work investigated the possibility to exploit woody forest residues and wood, obtained from forest maintenance activities and meteorological extraordinary events, as an additional material for clean energy production. These materials were collected from the Renon highland near the city of Bolzano (South Tyrol, Italy) and they were analyzed in terms of their main physical and chemical characteristics. Subsequently, these materials were tested in an open-top gasifier installed in the Bioenergy and Biofuels labs of the Free University of Bolzano. The tests have shown the potential to use these as feedstocks for clean energy production, although small differences in their respective performances have been observed. The differences mainly depend on the different characteristics of these materials. To evaluate the technical feasibility of using these materials, for additional energy production through an existing CHP plant, the possibilities investigated are twofold: the evaluation of a specific mixture of these residues, capable to guarantee a homogeneous feedstock to the gasifier, and the possibility to consider the wood from extraordinary events as a buffering material in periods of the year when the production of woody forest residues is reduced. The preliminary results obtained from the gasification experiments of these residues were encouraging; however, additional research is required to optimize the process for practical application., Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 458-462

The management of tar has been at the center of attention for all gasification plants. Removing tar compounds from the producer gas is done by a combination of condensation and filtering processes. Contrary to the gaseous phase, there is not a standardized methodology for extracting the tar compounds that are trapped in the porous of chars. Thus, in this study a novel hydrothermal/ ethanothermal extraction method is proposed, which is performed in a hydrothermal autoclave reactor. Our proposed method is compared with two conventional extraction methods, i.e., shaking and ultrasonic extraction for 15 and 30 minutes. Ethanol and water are used as solvents separately but also in mixtures of 50:50 ratio. The characterization of the liquid extracts was done by assessing the pH and the Total Phenolic Content. All samples were measured to have very basic pH values with most values being over 10. Among all the extraction methods, ultrasonic extraction had the most basic pH extracts. In respect to the total phenolic content, for all the different solvents and all the extraction times our proposed method of hydrothermal/ ethanothermal extraction was able to extract multiple times the amounts that were extracted by the other two methods., Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 1000-1003

The aim of this work is to develop a gasification model based on the thermodynamic equilibrium approach, able to overcome the issues of the classical equilibrium strategy, that computes the gasification products using the Gibbs energy minimization method at fixed temperature and pressure. The model is applied to describe the gasification process of an open top pilot-scale gasifier placed at the Bioenergy and Biofuel Lab of the Free University of Bolzano. The data used for the tune up of the model have been collected over a period of three years of gasification experiments using several biomasses (wood chips, wood pellet, torrefied pellet and wood pellet mixed with char) at different gasification conditions (from 0.17 up to 0.35 of ER value). In fact, a correction factor has been introduced versus the entire set of experimental data to account for the differences between the theoretical hypothesis implemented in the equilibrium model and the real non-adiabatic system. The model outcomes show a good agreement with the experimental data in terms of parameters of interest for gasification such as producer gas LHV, producer gas yield, char yield and cold gas efficiency. Potential outcomes of this research are, firstly, the characterization of the plant behavior without the need of estimating/measuring the average gasification temperature and secondly, the development of a gasification model suitable for the plant control management and in general able to predict the behavior of fixed-bed gasifier systems., Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 506-510

Biomethanation of biomass-derived syngas is a promising renewable methane production technology with high carbon efficiency, but there is lack of evidence on how process scale-up and biomass cost impact the profitability of full-scale processes. In this study, we developed a set of techno-economic models for the assessment of process competitiveness under several scales and configurations, integrating syngas biomethanation with Power-to-Gas (PtG) services, carbon capture and storage (CCS) and biomethane liquefaction. The results indicate that the incentive mechanism currently supporting biomethane production from anaerobic digestion in Italy would grant profitability for small-scale (6 MWth input) syngas biomethanation plants at biomass costs equal to or below 80 €/t. Under the Danish mechanism, such biomass cost corresponds to 60 €/t. At the currently valid biomass cost of 150 €/t, an 8-MW system delivers a minimum selling price (MSP) of 1.07 €/Nm3 biomethane, but such MSP increases substantially when PtG and CCS are included., Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 1-7

The aim of this work is to integrate, in the same reactor, subcritical water extraction with a downstream Hydrothermal Carbonization (HTC) process for apple pomace valorization. For this purpose, tests were run in a 250 mL stainless steel reactor. The first extraction step was performed in a temperature range from 100 to 125°C and pressures above the corresponding saturation to maintain the water in a liquid state. Then, extraction residues were characterized by moisture and ash content, elemental composition, and higher heating value. Thermogravimetric Analysis (TGA) and deconvolution of Thermogravimetric Derivative (DTG) peaks were used to identify free sugars and hydrolyzed protein. Afterwards, HTC test of spent material was performed at 220 °C for 3 hours. The resulting solid phase (hydrochar) was collected and characterized as well., Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 611-615

The present work aims at investigating the valorization of biomass forestry residues by means of experimental analysis on a small-scale open top gasifier. In order to evaluate the effect of high bark content, experimental test have been performed in an open-top gasifier with increasing shares of bark and woodchips and different levels of secondary air supply, used as adjustable parameter for the optimization of the conversion process. Samples have been characterized using standard methodologies for assessing the moisture and ash content, the elemental composition and the calorific value. Moreover, the bark content in the standard woodchips has been quantified to be 8 % in mass. High content bark samples (30 % and 80 % in mass of total bark) have been then prepared mixing the standard woodchips with barks. Using the prepared mixtures, gasification tests were performed with an open-top gasifier installed at the Free University of Bolzano. This specific pilot-scale gasification plant is a downdraft system, where both gas and feedstock move downward as the reactions proceed. The core of the gasification system is a stainless-steel cylindrical reactor. The air required for gasification is partly drawn from the top, and the remaining from the air nozzle at the char combustion zone. The results of the experimental campaign showed that the generally negative impact of bark addition, demonstrated by a reduction – at a set level of secondary air – of the calorific value of the producer gas and of the cold gas efficiency, can be counterbalanced acting on the secondary air and therefore on the equivalence ratio of the process, a parameter that has been demonstrated to allow an optimization of the process as a whole thanks to a linear correlation with the cold gas efficiency., Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 407-410

This work deals with the utilization of lignocellulosic low-cost biomass-residues for the generation of syngas suitable for the upgrade to biofuels, i.e. Fischer-Tropsch (FT), biomethanation. A series of experiment was carried on using three types of biomass: two types of biomass residues, i.e. vineyard pruning and bark, and woodchip. The experiments were carried on in a batch fixed-bed reactor at 700 °C and 800 °C and at different steam flow rate (0.04 g/min and 0.20 g/min). The results show that it is possible to achieve optimal syngas composition for each biofuels upgrade pathway. For Fischer-Tropsch synthesis, a H2/CO ratio of approx. 2 is achieved using the low steam flow rate at 700 °C for pellet and 800 °C for woodchip and bark. For the biomethanation synthesis, the highest hydrogen-to-carbon ratios are achieved with woodchip at 700 °C and low SF, and for pellets at 800 °C and low SF. The results of this work provide further evidence towards the feasibility of renewable biofuels production. (200 words), Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 440-444

The aim of this study is to investigate the possibility of enhancing the gasification process using a pre-treated biomass that presents higher heating value, higher C/O ratio and less moisture content than untreated biomass. The aim is to assess the gasification parameters that can be modified in order to achieve the best performance of the gasification system. These research studies have been carried out in collaboration with the Centre RAPSODEE (UMR CNRS 5302, IMT Ecole de mines Albi-Carmaux, France) and the Free University of Bolzano (Italy). The torrefaction of standard pellets is realized using a lab scale rotary kiln unit at RAPSODEE. On the contrary, the gasification tests are carried out at the Free University of Bozen-Bolzano by means of a fixed bed open top gasifier. The tests of pellets torrefaction has been carried out at 250°C and 270°C with two repetitions in order to obtain about 60 kg of pellets for each torrefied condition. The used feedstock is a standard French pellets produced from sawdust of oak and beech following the standard EN 14961-2 (“Wood pellets for non-industrial use”). The pellets are characterized before and after the torrefaction pre-treatment. The gasifier used for the gasification tests is an open top pilot-scale gasifier placed at the Bioenergy and Biofuel Lab of the Free University of Bolzano. The plant is an open top downdraft system, where both gas and feedstock move downward as the reactions proceed. The main difference between un-treated and torrefied pellets is the moisture content. In addition, a slight increase in terms of carbon content and LHV and a slight decrease in terms of volatile matter are observed by moving from standard to torrefied pellets. The torrefied pellets seem to reach lower performances in terms of cold gas efficiency (CGE) and char yield with respect to the standard pellets. However, the trends in terms of ER and CGE suggest that moving toward higher values of ER, higher values of CGE could be reached independently of the material used., Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 403-406

In this study, an Aspen Plus model was developed to compare the techno-economic performance of two processes comprising integrated biomass gasification, low-pressure water and methanol syngas scrubbing, electrolysis and syngas biomethanation. The first process operates standalone biomethanation (SAB) of syngas and can produce approximately 38,000 Nm3/day of bio-synthetic natural gas (bSNG). The second process (integrated biomethane-biomethanol, IBB) exploits the unconverted carbon stream from the biomethanation process to co-produce biomethanol via direct catalytic CO2 hydrogenation. In addition to the same bSNG output of SAB, the IBB process can produce 10 t/day of biomethanol. Liquid scrubbing delivers a 64% reduction in specific work input before electrolysis, compared to conventional syngas conditioning, but it increases the demand for additional hydrogen. Although IBB shows limited energy efficiency gains due to the large increase in electrolytic hydrogen demand, it shows a substantial improvement (+27%) in biomass-to-fuel carbon efficiency. The SAB and IBB processes generate a bSNG minimum selling price of 2.38 €/Nm3 and 3.68 €/Nm3, respectively. High electrolysis costs primarily cause the bSNG market price gap to remain substantial, namely in the range of 0.19 – 0.27 €/kWh. Intensive fiscal support is required to sustain the co-production of biomethane and biomethanol under the proposed process scheme., Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 520-525

Fixed-bed biomass gasification is a promising dispatchable option of renewable energy sources to serve flexibility demands in electricity production. To experimentally investigate this potential, this contribution analyses an industrial small-scale fixed-bed biomass gasification system for demand-oriented electricity production by evaluating the effects of an electric power change in terms of transition duration and control accuracy. Therefore, the steady-state operation at different loads and the transient behaviour of the gasification system during stepwise changes of the electric power are evaluated based on measured and derived process parameters. The results from a great number of test runs performed reveal the potential for rapid changes of the electric power (100 kW to 150 kW in less than 1.5 min), a good stationary accuracy for operations at nominal (150 kW ± 3.7 kW) and partial load (100 kW ± 5.1 kW), and hardly any negative effects on the gasification performance (e.g. cold gas efficiency and equivalence ratio remain almost constant during load changes). However, results from partial load reveal an increase in process fluctuations due to the control strategy used. To unleash the systems’ full potential of flexibility, a more advanced control strategy should be applied., Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 464-476

Hydrothermal carbonization (hereinafter, HTC) is an interesting thermochemical process through which wet biodegradable residues can be directly transformed into value added products. The main HTC products are the hydrochar, a solid carbonaceous material, and several chemicals dissolved within the liquid phase. In the last years, a vast research effort has been conducted on the study of the chemical reactions occurring during this process. In particular, the evolution of the chemical species during HTC has been the focus of many research activities. In order to understand this evolution, tests have commonly been performed using batch reactors, that have been cooled down at different process times to sample the process products for further analyses. However, the cooling down process can alter the real chemical and physical properties of the HTC products, and thus the analyses might produce not completely representative results. In order to avoid this and to allow a continuous sampling of the products during the process, a new reactor design has been developed by the Italian company HBI. With this new reactor, direct products sampling can be conducted. The reactor was tested with model compounds, such as wood and cellulose, and preliminary results have been described in this work., Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 1146-1148

The aim of this study is to assess the load modulation capability of a pilot plant open top downdraft gasifier using standard wood pellet. The input gasifying agent, which is air, can be split into primary air (from the top) and into secondary air, where the remaining required air is fed directly into the reduction zone of the reactor through a nozzle. The novelty of this research reside in the investigation of the effect of the supplied secondary air flow rate at different loads, with the aim to improve the load modulation capabilities by means of controlling the air distribution and achieving the higher possible conversion efficiency with varying amounts of producer gas power production. The gasifier was tested at different loads. The equivalence ratio (ER) is related to the mass flow rate of secondary air, thus by increasing the secondary air the equivalence ratio increases as well. The results confirm that it is possible to have high gas conversion at different loads using the mass flow rate of secondary air as a control parameter for the management of the equivalence ratio into the reactor., Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 802-806

Assessing the operational behaviour of biomass gasification systems is a crucial basis for further improvements in terms of operational behaviour and robustness in order to increase the technologies’ operational and economic viability. However, in most fixed-bed biomass gasification systems not all parameters required for the assessment can be measured directly. Typically, unknown parameters are determined by using as many balance equations as parameters have to be determined neglecting the additional information provided by other available but not chosen balance equations. Thus, these approaches do not incorporate all measurement data available resulting in a lack of reliability in their results. A detailed analysis of these approaches emphasises that even small deviations in the measurement data can lead to significant deviations in the calculated parameters, demonstrating that individual choices of equations can be highly sensitive regarding measurement uncertainties. Therefore, an adjusted weighted least squares approach is developed utilizing an overdetermined system of equations incorporating all balance equations simultaneously. Thus, all measurement data available is taken into account, minimizing the influences of measurement uncertainties on the determined parameters. A comprehensive analysis shows that this approach is less sensitive to measurement uncertainties, allowing for a more reliable and accurate assessment of fixed-bed biomass gasifiers., Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 849-860

Gas-fired and coal based power generation plants result in the emission of CO2, a major greenhouse gas responsible for climate change. On an average, the flue from such power plants contain approximately 12– 17 vol.% CO2, 75 – 77 vol.% N2 and ~ 4.4 vol.% O2 with fractions of CO, NOx, H2 and SO2 in ppm range. While the capture and storage of this CO2 stream have been addressed actively in the literature, or even implemented rather unsustainably, its application in the fuel making process is imperceptibly addressed. This work examines the thermochemical biomass conversion with air and CO2 as gasification media to explore the possibilities and limitations of CO2 capture and its application in the fuel making process by the employment of the Boudouard reaction in the high temperature char zone to yield carbon monoxide. While this study revolves around the direct use of CO2 from the flue of diesel engines. The experimental investigations are based on the configuration of a downdraft reactor utilizing dried biomass pellets as feedstock. The mass flow rates of air and CO2 are measured and controlled using calibrated mass flow controllers and the biomass consumption rate is measured by placing the reactor over a digital weighing balance. A complete carbon balance is implemented in order to analyse the rate of formation of char under various conditions. This work demonstrates a mode of effective utilization of CO2 from the flue of exhaust gases in the power generation process that can even be integrated with a bio-refinery plant., Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 732-736

Char, a carbonaceous solid residue derived from biomass gasification, exhibits remarkable properties very similar to activated carbon (AC) and potentially it could replace it in many applications. In particular, this study investigates the feasibility of using char from commercial biomass gasifiers as catalyst support for the Fischer-Tropsch (FT) synthesis. 20% Co-based catalysts supported on char and on a commercial AC selected as reference, were prepared through incipient wetness impregnation and characterized through elemental analysis, physisorption analysis, thermogravimetric analysis, XRD and SEM techniques. Both catalysts were tested for 25 h in a fixed bed reactor operating at 240 °C, 16 bar, H2/CO = 2 and 3600 mL g-1 h-1. The AC-based catalyst proved to be more active than the char-based one. The CO conversion measured using char as support (2.6% average value) was very low compared to the one measured using AC (27.68% average value). Only hydrocarbons in the range of C1-C4 could be detected for the char-based catalyst, while also hydrocarbons in the range of C5-C10 could be detected for the AC-based one. The dissimilarities in the catalyst performances are mainly attributed to the intrinsic differences between the two catalysts in terms of thermal and structural stability, and porosity development., Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 940-946

This study wants to investigate a possible valorization route for char from biomass gasification taking advantage of its similarities to biomass-derived activated carbon in terms of properties and mechanisms of formation and assess its suitability for CO2 adsorption. Char was collected from a commercial gasifier operating in South Tyrol, Italy, and characterized through elemental analysis, X-ray diffraction technique, physisorption analysis and scanning electron microscopy. The CO2 adsorption/desorption capacity of the char was investigated through thermogravimetric analysis at different adsorption temperatures (Tads = 50 - 100 °C) and CO2 concentrations (CO2:N2 = 1:1 - 0.8:0.2). CO2 adsorption capacity of char decreases with temperature and increases with CO2:N2 ratio. The highest CO2 uptake of 3.4 % resulted for Tads = 50 °C and CO2:N2 = 1:1., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 760-764

In the last years, the interest concerning the energy utilization of common reed is considerably increased. This topic is of particular interest also in the region of South-Tyrol (Italy), in which the management of alpine lakes requires a regular harvesting of this wetland plant. Different possibilities exist for the utilization of this resource; one of them is the utilization for energy production. The aim of this work is to assess the energy potential of common reed for the case study of Caldaro lake (Italy), where the co-combustion of reeds in an existing woodchip boiler could be a feasible application. For this reason, different co-combustion tests have been performed in a 3 MW woodchip boiler, varying the reed share (about 30 % and 50 % in terms of dry matter) and pre-treatments (as harvested or crumbled material). According to the results of the campaign, the co-combustion of reeds did not significantly affect the operation of the furnace. The utilization of reed without pre-treatment (i.e., as harvested) has shown to be problematic for the feeding of the reed-woodchips mixture into the furnace. A share of about 30 % of crumbled reeds has be proven to be effectively fed to the furnace without any modification to the existing feeding system (i.e., rakes on the floor moving back and forward)., Proceedings of the 24th European Biomass Conference and Exhibition, 6-9 June 2016, Amsterdam, The Netherlands, pp. 772-776

The aim of this work is to assess the thermal exchanges and the volatile distribution within a single wooden particle subjected to pyrolysis. A two dimensional axial­symmetric representation of the particle has been used, and the mass, momentum and energy conservation equations have been integrated by means of a finite­volume method. Wood has been considered as an isotropic porous medium. The thermal properties of the solid reagent medium (e.g., thermal conductivity and diffusivity of wood) have been measured through laser flash analysis (LFA). Boundary conditions have been set in accordance with the experimental tests used for the model calibration. The model has been in fact calibrated versus experimental data that have been obtained during pyrolysis tests under non­oxidant (340 cm3/min of Helium) controlled conditions, performed with spherical wooden particles of different sizes (19.0 mm and 31.8 mm diameter) in a tubular stainless steel reactor (internal diameter: 3.8 cm; length: 30.5 cm) inserted in an electrically heated furnace. The temperatures on the surface and in the center of the wooden sphere have been monitored during the process, confirming the behavior shown in other studies. In addition, an innovative intraparticle sampling methodology have been applied, in order to analyze through gas chromatography the evolved gas at the center of the particle. In particular, the detected components have been: CO2, CO, CH4, C2H6, C2H4 and H2. The proposed approach allowed a detailed characterization of the distribution of the evolved gas inside the particle, providing useful information for the assessment of the reaction happening inside it., Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 912-919

The aim of the present work is to investigate the chemical and physical properties of the grass psecies Phragmites australis (known also as common reed) and to characterize the products derived from its pyrolysis. Calorimetric analysis of different reed samples highlighted an interesting heating value of about 17 MJ/kg on a dry basis. Nevertheless, this feedstock has been found to be characterized by considerable ash content and rather low ash melting temperatures. These aspects are essential for the correct design of a possible treatment plant for the thermochemical conversion of herbaceous biomass. Furthermore, reed thermal behavior has been assessed by means of advanced thermal analysis, consisting of thermogravimetric analysis (TG) coupled with the simultaneous analysis of the evolved gases by means of gas chromatography/mass spectrometry (GC-MS) and infrared spectroscopy (FT-IR). Several pyrolysis tests have been then performed in a bench scale pyrolysis apparatus, investigating different process temperatures (between 300°C and 700°C) with an heating rates of 50°C min-1. In each test, the condensable fraction (tar) was collected according to the technical standard CEN/TS 15439 and analyzed through gas chromatography in order to detect the content of polycyclic aromatic hydrocarbons (PAHs). Moreover, the permanent gases were analyzed on-line by means of a microGC system. A detailed economic analysis is required to give a reliable assessment of the applicability of reed in thermochemical conversion plant. However, a proper feasibility analysis cannot be performed without taking into account the physical-chemical characteristics of such biomass, its thermal behavior and the characterization of the process products and by-products. The results of this work are crucial for this purpose., Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 1134-1139

The work presented is a part of a wider project with the target to realize in­deep studies on the applicability of the hydrothermal carbonization process to the treatment of high moisture biomass. To get this challenging objective, a batch reactor has been built to perform preliminary tests to get insights on the thermochemical process. Several substrates have been carbonized, obtaining interesting results, useful for the modelling stage. A numerical model of a batch hydrothermal carbonization reactor have been developed. The model integrates both mass, momentum and heat equations within the reactor domain by means of finite volumes method (f.v.m.) approach. Convective and radiative exchange between the reactor and the fluid within the reactor have been implemented in the f.v.m. model. To calibrate the model, experimental tests have been performed to collect data referred to temperature profiles (outside and inside the reactor) and pressures. Under two strong assumptions (mono­component and mono­phase fluid, which fulfils the reactor), it has been possible to estimate the behaviour of an equivalent fluid (eq_fluid), in terms of thermal properties of the fluid (thermal capacity, thermal conductivity and thermal diffusivity). The foreseen upgrading of the model can help to obtain a better description of the process., Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 987-990

GAST project stands for ‘Experiences in biomass GAsification in South-Tyrol: energy and environmental assessment’ and has raised an opportunity to monitor and analyze small scale biomass gasifiers in the region of South Tyrol (Italy). Free University of Bozen-Bolzano, in collaboration with other partner research institutes, is implementing this project in order to assess a test methodology for small scale gasification systems. In the framework of this project, a monitoring campaign has been carried out on three different gasification technologies for combined heat and power (i.e., CHP) generation. The monitoring has been performed in agreement with the test methodology proposed by the “Raccomandazione CTI 13” standard, i.e., a guideline about the contracting and commissioning of gasification systems recently published by the Italian Thermotechnical Committee Energy & Environment (CTI).The present work aims to assess the test methodology that should be utilized to evaluate both the energetic performance and the environmental impact of a small scale CHP gasification system. In addition, the main technical issues arisen from the measurement campaign and from the lab analysis have been discussed., Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 579-584

In this paper, a study on the reaction kinetics of the hydrothermal carbonization (HTC) process is presented. A fundamental piece of information for the design of a HTC process is the knowledge of its kinetics: the process conditions do not allow the establishment of thermodynamic equilibrium and the reaction kinetics approach becomes mandatory for understanding how the process occurs, evolves over time and depends on the operating conditions. Experimental data have been collected applying the HTC process to an organic waste residue coming from the wine­making industry: the grape marc. Starting from the yield and analytical results, a kinetic model based on a two­step kinetic mechanism was calibrated. The activation energy and pre­exponential factors of the various degradation reactions were determined by means of least square optimization versus the experimental data. The calibrated model allowed a characterization of the HTC time scale under different process conditions, showing that a two­step reaction mechanism can be suitably used to describe the evolution in time of the hydrochar yield at different process temperature, Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 1269-1273

This study investigates the feasibility of olive pomace as an energy source through combustion in a biomass burner. Samples of pomace have been dried under controlled conditions utilising a moisture analyser. A modified Midilli model was developed and found to be the best at predicting the experimental data (±10% error). The model suggests that the total drying time required to dry a projected amount of olive pomace in the future is realistic. Simultaneous thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis have been also carried out on the dried olive pomace. The pomace devolatilisation and the evolved gases during the decomposition process have been also analysed by a coupled infrared gas analyser (IR) up to temperature of 1000°C. Additionally, suitable burners were found to meet the requirements of the grove to produce heat and/or electricity for domestic consumption utilising olive pomace and prunings. The payback period for the considered system, assuming all the pomace and prunings from the harvest is utilised, is under 5 years. This assessment is heavily dependent on labour costs associated with pruning and pomace drying. In the future, an extensive inclusion of all relevant cost incurred should be considered for a more in depth analysis., Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 230-234

In the last 18 months, several South-Tyrolean entrepreneurs have decided to invest in the biomass gasification technology, clearly conveying strong interest in the sector of small scale cogeneration plants. This was unexpected because the current state of this technology is still not completely mature for the market. On one hand, there is a clear economic interest of the companies that can obtain incentives for the selling of electricity produced by biomass. On the other hand, there is a scientific and a commercial interest in the demonstration of the energetic efficiency, environmental performance, reliability and optimization of this technology. At the moment, this type of survey is unique in Italy. In addition, it can support the local public administration, by providing useful tools for the authorization procedures of small biomass gasification plants. Currently, 14 small scale gasification plants are operating or fully authorized in the region of South Tirol. During the preliminary screening the most frequent technological choices of the constructors are gasifiers from Spanner RE and Burkhardt. Until the end of the year approximately 35 plants are projected to be operational or authorized., Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 891-901

The pursuit of better energy performance of buildings led o the recourse to more detailed instruments of analysis, requiring more complex and detailed inputs, such as the hourly weather data. In this work, the representativeness of the test reference year (TRYEN) weather data, recently developed in Italy in accordance with the procedure proposed by EN ISO 15927-4:2005, has been studied evaluating the energy performance – energy needs and peak loads – of a set of different simplified reference buildings by means of TRNSYS simulation code, using both the TRYEN and the TRYEN source multi-year collected weather series for 5 north Italian locations. The results have been analysed by means of both descriptive and inferential statistics. The variability of energy performance has also been correlated with the envelope characteristics, in order to estimate a sensitivity of the different buildings to the weather data variability.

The aim of this work is the energy efficiency assessment of micro cogeneration systems (MCHP) based on biomass gasification for residential application, using a multistage modeling approach. Particular attention has been paid to the optimization of the component assembly, focusing on configurations that allows all the devices operating in their optimal configuration. The gasification stage has been then modeled through an enhanced (i.e., gas¬solid) thermodynamic approach using the CANTERA solver and the Gri¬Mech thermodynamic properties. Several values of temperature and amount of gasifying agent have been taken into account for the simulations. The efficiency of the whole MCHP system has been evaluated supplementing the simulation of the gasification stage with the energy balance of the cogeneration set (i.e., internal combustion engine) and implementing the developed routines in the Matlab¬Simulink environment. In the simulations, the plant is supposed to supply thermal energy to a building considering different scenarios. Dynamic simulation through EnergyPlus software have been performed. The building¬system interactions under different operating and boundary conditions have been assessed. The paper shows the optimal operating conditions and the system size range for residential applications. The gasification¬based micro CHP technology has an high potential and also substantial room for improvement., Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 1058-1064

The aim of this paper, inserted in the frame of SuWaRest (Sustainable Water management and wetland Restoration in settlements of continental-arid Central Asia) project, is to present the results of a preliminary techno¬ economic evaluation of reed potential as energy source, with particular regards to Wuliangsuhai Lake region (Inner Mongolia Autonomous Region, China). In order to estimate the reed productivity, reed samples have been collected in October 2011, both in the lake and in the land around it and also characterized by means of elemental and calorimetric analysis. The theoretical yield and the equilibrium composition of the reaction products (syngas and char) of reed thermochemical conversion processes (pyrolysis and gasification) has been estimated through an enhanced gas-solid equilibrium model. In addition, in order to collect information about the current situation of reed market, several interviews of officials, scientist and local people have been carried out. The collected information has been useful for a preliminary techno-economical evaluation, representing a first step in the achievement of the project purpose regarding the energetic utilization of reed., Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 2353-2361

In this paper a practical test of an innovative on-line tar measuring system has been carried out using the reference standard for tar sampling (UNI CEN/TS 15439) and off-line analysis approach. Samples of common reed -collected in Inner Mongolia (China) -have been characterized by means of physical-chemical and thermal analysis. Several experimental tests have been performed in a bench scale pyrolysis apparatus (Free University of Bolzano, Italy) setting different process temperature (300-700°C) and a heating rate of 50°C/min. In each test the condensable fraction (i.e., tar) has been collected and analysed. These analyses have been supplemented with an innovative on-line tar measuring methodology, developed at the Graz University of Technology (Austria). The system consists of a lab scale fluidised bed gasifier coupled with an optical measurement cell. In the measurement cell a UV light stream is produced by means of LEDs having different wavelengths (265nm, 285nm, 300nm and 365nm). The spectrum of absorbed light from the tar in the gaseous products can be detected through a photodiode, being proportional to their concentration. The integration between different analytical approaches on tar characterization has been useful to assess their capability and their potential application., Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 997-1004

The aim of this work, inserted in the frame of SuWaRest (Sustainable Water management and wetland Restoration in settlements of continental-arid Central Asia) project, is the individuation and feasibility evaluation of different scenarios of energy conversion of reeds (Phragmites australis), keeping into account torrefaction, pyrolysis and gasification paths. An enhanced gas-solid equilibrium model has been used in order to estimate the theoretical yield and the equilibrium composition of the reaction products (syngas and char) of pyrolysis and gasification processes. In order to evaluate the benefit of a torrefaction pre-treatment, the thermodynamic model has been coupled with a multiphase kinetic model calibrated with experimental data and able to predict solid, liquid and gaseous conversions in the torrefaction process. The experimental validation of the models results will be performed in a laboratory plant, which preliminary design is here presented. Reeds seem to be a suitable biomass for energy purposes and, thanks to its high abundance in the studied areas, could be an interesting energy source. A detailed economic analysis is request in order to give a reliable assessment of the process sustainability and to understand if reeds could represent - at least locally and in relation to the study sites - an alternative to the use of coal. The results of the present work will be crucial for this purpose., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 1501-1514

WOOD-UP is an applied-research project that aims to produce expendable results, with an impact on key sectors (agriculture, energy, environment) of the economy of South-Tyrol (ST). Recent research findings has suggested that biochar, one of the gasification by-products, may represent a valuable resource, when used in agriculture as soil amendment. However, the characteristics of the biochar produced in ST are only partially known, and its ability to improve soil fertility is still unknown. Moreover, the woody biomass used is rich in secondary compounds, which could be used by the pharmaceutical, cosmetic and food industry. These compounds could be extracted before the use of biomass for energy production, increasing the economic sustainability of the entire value chain. In this framework, the aims of this work were: 1. assess the state of the art of the gasification of woody biomass in ST; 2. physically and chemically characterize the biochar produced in ST; 3. study the effect of biochar application on the soil, through in vasu germination and phytotoxicity tests., Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 1080-1083

Small-scale gasification of woody biomass is a technology that has had a rapid development in the last years, mainly driven by favorable subsidization regimes. Biomass gasification process produces a minor fraction of solid carbonaceous by-product, known as char. Even though char presents chemical and physical characteristics that make it a potentially interesting and valuable product in the view of pushing gasification from a co-generative process to a poly-generative platform, economically viable solutions are not available yet and the disposal of char still represents a non-negligible cost in the plant management. For this reason, most of the recent developments in the small-scale gasification technology available in the market aim at reducing as much as possible the amount of material to be disposed, integrating into the plant an additional oxidizing section, i.e. afterburner, in order to have an outlet material stream mainly composed by ashes. The aim of the present work is to investigate an alternative solution for reducing the amount of generated char and at the same time increasing the efficiency of the whole conversion process. The proposed solution, investigated in a small-scale open-top gasifier installed at the Free University of Bolzano, is to recirculate the char inside the gasifier in order to increase the residence time and the conversion yields., Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 527-532

Char is the solid by-product of biomass gasification. Plant owners usually dispose of it at a cost, but its high carbon content and surface area could make it suitable for further applications. In this work, we studied its potential to adsorb hydrogen sulphide (H2S), a common pollutant, e.g. present in the producer gas of gasification, as well as in biogas from anaerobic digestion. We tested different samples of char collected from commercial gasification plants in South Tyrol (Italy). The adsorption was reproduced in a lab-scale fixed bed reactor. The results highlights that all samples could capture hydrogen sulphide, showing different adsorption performance. The surface area of the char and the ash amount seem to affect the removal capacity, although other properties of the materials are probably important. The inlet concentration of hydrogen sulphide does not influence the adsorption capacity significantly., Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 493-499

In this work, heat flux Differential Scanning Calorimetry (DSC) was used coupled with high-pressure crucibles to evaluate the enthalpy change of Hydrothermal Carbonization (HTC) applied to cellulose, wood, and digestate from an anaerobic digestion plant. The temperature program, constant heating rate of 5 °C/min up to 250 °C, then 3 hours at 250 °C, was run twice on each crucible containing the sample: in the first run the HTC process takes place and completes, in the second run (the blank) the thermal effect is not related to the process. The two curves are then subtracted to obtain the process enthalpy change. 8 mg of dry substrates and 64 mg of distilled water were used for each run. For each substrate, three replicates were performed. Results showed high reproducibility and agreed with the available literature about DSC of wood and cellulose. The results for digestate were in the same range, but lower due to the less energetic nature of the substrate. Interestingly, the enthalpy value related to wood showed higher standard deviation with respect to the one related to digestate., Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 1160-1163

The present study investigates the conversion of producer gas from biomass gasification for the production of liquid biofuels through Fischer-Tropsch (FT) synthesis. Since FT synthesis is a catalytically driven reaction, the catalyst properties play a crucial role in determining the hydrocarbon yields and spectrum. In this regard, the current work investigates two catalyst synthesis methods, wet impregnation (WI) and combustion synthesis (CS). The CS method utilized herein employed lean stoichiometry with the cobalt nitrate-citric acid reaction. Three distinct alumina supported cobalt catalysts were tested: one was synthesized with the WI method and two with the CS method at two different equivalence ratios (.=0.6, .=0.3). All the catalysts were tested for approximately 70 h, after stabilization, at 230 °C, 30 bar, H2/CO=2.1 and 2000 mL h-1 g-1. All the catalysts exhibit conversions higher than 40% and hydrocarbons in the range C1-C35 could be detected. The best performance is achieved by CS(.=0.6) catalyst., Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 1262-1265

The purpose of this work is to model a CHP system made up of an open-top downdraft gasifier and a 4kW single-cylinder diesel engine in operation at the Bioenergy & Biofuels Lab of the Free University of Bozen-Bolzano (Italy). In particular, the present study aims to couple a multi-stage and multi-phase thermodynamic model of the gasifier with a 0-D thermodynamic model describing dual fuel combustion inside the engine.Preliminary results have been obtained in terms of gas composition and engine power output. Future developments include enhancements of the predictive capacity of the modelling strategy, technical improvements in terms of gasifier automation and engine fueling diversification and finally the realization of a systematic experimental campaign in order to describe the behavior of the energy system in several conditions., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 788-793

Small-scale-woody-biomass gasification plants installation have seen a rapid growth in the last years in South Tyrol. More than 40 plants have been installed, producing about 42 GWhel and 84 GWhth, most of them exploited in local district heating grids. Among the energy production, char is produced to an extent of up to 2000 ton per year. At present this material is managed as waste, with an average cost of more than 300 k€ every year. Within this context and under the perspective of poly-generation (i.e., the generation of at least three valuable products), the Free University of Bolzano developed the Novel EXTension of biomass poly-GENERATION to small scale gasification systems in South-Tyrol (or NEXT Generation project), aiming to investigate the quantity, quality and environmental impact of the by-products of small-scale biomass-gasification-based CHP plant in South-Tyrol, and to assess possible route for their valorization. Thus, in this paper the NEXT project is described and the preliminary results are presented. Moreover, some important remarks on possible valorization pathways for char exploitation are provided., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 747-750