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Biomass gasification is a process known for its high potential in enabling the exploitation of residual biomass in the production of renewable electricity. At present one of the most favorable patterns from both an environmental and a sustainability point of view is air gasification coupled with an Internal Combustion Engine (ICE) for decentralized production. In order to have the best performances of the ICE to be run with the produced gas, the required technical specifications on gas purity can be achieved at an appropriate level by means of wet scrubbing. In wet gas cleaning approach, stages based on organic liquids (e.g. biodiesel) and water can be jointly adopted for the removal of contaminants. In the present work preliminary results for the regeneration of the wastewater stream produced at a gasification plant whose gas cleaning is carried out with a purification train based on biodiesel and water scrubbing are presented. To this aim three different fungal strains were selected and tested for their bioremediation potential, i.e. Bjerkandera adusta, Arthrinium sp, and Pleurotus ostreatus. Laboratory tests gave an overall positive response on the effectiveness of wastewater treatment by Bjerkandera adusta and Arthrinium sp. thus demonstrating that these microorganisms are able to metabolize, and therefore remove, both aromatic molecules typical of tar produced in gasification processes, and esters of fatty acids constituting the biodiesel used for gas washing in the first stage.

BLAZE aims at developing Low cost, Advanced and Zero Emission first-of-a-kind small-to-medium Biomass CHP. This aim is reached by developing dual bubbling fluidised bed technology integrated with high temperature gas cleaning & conditioning systems and Solid Oxide Fuel Cells. The technology is characterised by the widest solid fuel spectrum applicable, high efficiencies (50% electrical versus the actual 20%), low investment (< 4 k€/kWe) and operational (˜ 0.05 €/kWh) costs, as well as almost zero noxious gaseous and PM emissions, projecting electricity production costs below 0.10 €/kWh. This paper shows the midterm project achievements, i.e. the biomass waste gasification and SOFC tests, the overall simulation and the progress on the realisation of 25 kWe SOFC pilot plant., Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 472-479

This paper quotes an overview of the UNIfHY project results regarding pure hydrogen production from biomass gasification. Tests with different gasification agents (steam/air/oxygen) and at different temperatures showed syngas yield from 1.1 to 1.7 Nm3 dry/kg of dry biomass, hydrogen content from 20 to 40%-v dry, tars, particulate in the range of 10-20 g/Nm3 dry, sulphur and chlorine compounds in the range of 50-90 ppmv, ammonia up to 1600 ppmv. Candle filters showed particulate removal efficiency higher than 99%-wt. A portable purification system (PPS) consisting in a ZnO guard bed reactor, a water gas shift reactor (WGS), compressor and gas upgrading unit (PSA) was designed and realized. The system was proven to be operable stably and continuously in experimental runs lasting more than 12 h. Hydrogen production at concentration of 99.99%-v was achieved with an H2 yield from PSA of 66.4%. Based on the data collected, UNIfHY can reach an economic production cost of 3-10 €/kg H2 (in the range 4.00-0.04 t H2/day, respectively) with low environmental impact (0.5-2.4 kg CO2/kg H2) but targets have to be different for decentralised (40% efficiency, 10 years lifetime

The methanation of a real gas produced from almond shells via steam/oxygen gasification is investigated. The performance of an experimental Ni-containing catalysts (Ni23.7Mg56.3Al20) was evaluated by using the material prepared in grains of 1-2 mm. The real gas was enriched with hydrogen at two different H2/COx mole ratios. All tests were carried out at operating conditions of 400 ÷ 450 °C and 25 bara. Checks with a defined reactive gas mixture provided indication about the activity state of the catalysts before and after the methanation. During all the stages of the tests the outlet gas composition was monitored and after each complete run the catalyst analyzed. Under the operating conditions adopted, the experimental catalyst showed a higher methane yield (+10% and +44%) at both H2 enrichment levels and no carbon deposition was observed, as demonstrated by after-test catalyst samples evaluated via Raman spectroscopy coupled with optical microscopy and SEM-EDAX analysis. © 2017, ETA-Florence Renewable Energies. All rights reserved.

Energy valorization via gasification of the solid residue (digestate) collected in a process of anaerobic digestion (AD) of blended fermentable feedstocks was considered. A rotary kiln reactor was adopted to collect data on the process performances when CO2, steam and mixes of them, were used as gasifying agents. Preliminary experimental campaigns were carried out at 800 °C by using a dried digestate having 64 %-wt volatile matter, 10 %- wt fixed carbon and 26 %-wt ash. Based on the total amount of supplied digestate, at the considered operating conditions, feedstock conversions in the range 59-63 %-wt, were achieved. By using the experimental data (i.e. amount of final residue, yield and heating values of the producer gas) in a simulation model of the gasification process, mass and energy balances were estimated. Among the different process conditions considered, the digestate gasification with preferable, although preliminary, operating conditions resulted that one carried out using only CO2 at a CO2/Feedstock ratio around 0.26 by weight. At this operating conditions, for the cold gas efficiency and the producer gas fraction to be used for covering the heat duty at the rotary kiln, values of 69 % and 28 % were respectively estimated. In all other considered conditions, the estimated values were found lower. Chance for process improvements are however predictable. © 2017, ETA-Florence Renewable Energies. All rights reserved.

The methanation of a real gas produced from almond shells via steam/oxygen gasification is investigated. The performance of an experimental Ni-containing catalysts (Ni23.7Mg56.3Al20) was evaluated by using the material prepared in grains of 1-2 mm. The real gas was enriched with hydrogen at two different H2/COx mole ratios. All tests were carried out at operating conditions of 400 ÷ 450 °C and 25 bara. Checks with a defined reactive gas mixture provided indication about the activity state of the catalysts before and after the methanation. During all the stages of the tests the outlet gas composition was monitored and after each complete run the catalyst analyzed. Under the operating conditions adopted, the experimental catalyst showed a higher methane yield (+10% and +44%) at both H2 enrichment levels and no carbon deposition was observed, as demonstrated by after-test catalyst samples evaluated via Raman spectroscopy coupled with optical microscopy and SEM-EDAX analysis., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 1245-1247

Steam/O2 biomass gasification campaigns were carried out at a 1000 kWth pilot plant based on an internally recirculating bubbling fluidized bed (ICBFB) reactor. Tests were carried out at different biomass feeding rates and comparable operating conditions, that is: 0.20-0.22 ER, 0.38-0.41 Steam/Biomass and 830-880 °C gasification temperature. Almond shells were supplied to the reactors at 140 and 180 kgwet/h. The two gasification campaigns showed comparable overall performances. Gas yields and carbon conversions of about 1.0 Nm3dry/kg(dry, Biom) and 85 %(wt, daf) were respectively estimated. Larger differences were found in the gas composition and contaminant loads. In the first case, it was observed an average dry gas composition of: 30-33 %v H2, 28-32 %v CO, 22-27 %v CO2, 9-11 %v CH4, up to 2 %v C2+, in the second a higher CH4 and lower H2 contents were instead achieved. The highest particles and tars loads were in the ranges 12-16 g/Nm3dry and 12-18 g/Nm3dry, respectively. Finally, H2S, HCl and NH3 were all found in the range: 60-110 ppmv. In the whole, the gasification test campaigns allowed to gain relevant evidence about the operability and the performance of the gasifier., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 550-554

To make biorefinery processes valuable from both economical and energy perspectives, all components of the starting feedstock need to be properly valorized. In the present work the results obtained in steam/oxygen gasification tests on a lignin rich residue from second generation bioethanol production process are presented. The residue was collected at the end of a process of simultaneous hydrolysis and fermentation, adopted to convert sugars from steam-exploded biomass. The gasification tests were carried out with a bubbling fluidized bed reactor at: 850 °C, 1 atm, 0.3 equivalence ratio (ER) and 0.6 steam/biomass (S/B). Under these conditions, it was found an average dry gas composition of: 25%v CO, 37 %v H2, 30 %v CO2, 7 %v CH4, 2% C2+ and a gas yield of 1.3 Nm3/kgdaf. Clogging of the feeding screw and appearance of bed defluidization were occasionally observed. Nevertheless, the gasification tests were run for several hours without interruption. Based on the data of performance of the gasification facility it was possible to evaluate the potential of power production. The electrical output was found consistent with the internal needs of a commercial plant for bioethanol production, sized to process up to 200 ktonnes/y of biomass., Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 430-434

Performance tests have been completed with a SOFC unit fuelled with syngas produced from biomass gasification reactors, properly conditioned and cleaned. Three series of tests at bench and industrial scale have been completed. The results of the tests indicate that cleaned syngas, from both steam blown and oxygen/steam blown gasification reactors, is a feasible fuel for anode supported SOFC cell. Cell performance on cleaned syngas is comparable or better than SOFC cell performance fuelled with the reference, hydrogen/nitrogen gas mixture. Several potential issues for the integrated SOFC/gasifier operation have been identified. Proper humidification of the gas stream, necessary to avoid carbon deposition, is critical for the long term cell performance. The presence of larger amounts of methane and higher hydrocarbons may lead to SOFC cell cracking due to large temperature gradients resulting from internal reforming process., Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 827-831

Paper industry is an “energy intensive” sector, therefore an increasing fraction of energy requirements is currently fulfilled by self-production, the most common solution being represented by gas-fired CHP plants. Moreover, the growing use of recovered paper and board as the raw material requires rational solutions for the management of the refuse originated by the mechanical separation of gross impurities from the usable fibre. A preliminary assessment of a novel solution for biomass and waste valorisation in paper mills, based upon the thermal gasification process and the subsequent co-firing of producer and natural gas in a gas turbine was performed. Preliminary waste characterisation shows that it has a remarkable LHV of 27.5 MJ/kg, thus confirming its potential use as a fuel for a thermo-chemical process. According to pilot tests results, a fuel gas with an excellent LHV of nearly 30 MJ/Nm³ can be produced via steam gasification. Furthermore thanks to producer gas high light hydrocarbons fraction, gas turbine performance should not significantly deteriorate due to the co-firing approach. The proposed solution, for the investigated case study, allows to save around 20% of natural gas consumption with an estimated payback period for the investment of only about 8 years., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 1519-1524

Tests of steam/O2 gasification were carried out at a 10 kWth internally circulating bubbling fluidized bed (ICBFB) reactor in the presence of a new catalytic bed material (10% Fe/Olivine). For comparison, reference tests using unmodified olivine were also carried out. The ICBFB reactor was operated at the gasification conditions of: 855 °C, 0.33 ER, 0.64 S/Bdaf, atmospheric pressure. During the gasification tests, the raw gas was monitored with respect to water content, gas composition and contaminants (i.e. tar and dust). Char residue was also determined. By comparing the results, the gasification yield and the gas composition were found very similar. On average the gasification yield was found to be about 1.2 Nm3/kgdaf, and the fuel gas have a dry composition of about: 30 %v H2, 25 %v CO, 35 %v CO2, 7 %v CH4 and 3 %v light hydrocarbons. On the contrary, the 10%Fe/Olivine resulted significantly more effective towards the tar removal than unmodified olivine. From the chromatographic analysis, it was evaluated a tar reduction efficiency of 38 % by weight. As far as concern the particulate content, a roughly double content in particulate was measured. The residues collected showed an appreciable content in fine particles originated from the 10% Fe/Olivine bed material. Therefore, compared to the unmodified olivine, increased brittleness of the new bed material was detected., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 1426-1431

Gasification tests were carried out in an internal circulating bubbling fluidized bed reactor injected by water steam and oxygen, working at thermal input of about 4 kW. The input streams to the gasifier (biomass, water steam and oxygen) and output ones (char, water and syngas) were quantified to characterize the chemical efficiency of the process. The produced syngas having a GC­MS tar content of 10.1 g/Nm3dry, which molecular composition was carefully ascertained, was cleaned in a scrubber. Two different scrubbing liquids were tested: environmentally friendly bio­diesel and water. Their tar removal efficiency was determined measuring the tar content of the syngas downstream of the scrubber. It was ascertained that the bio­diesel scrubbing removes 99% of the tar in syngas, while the water scrubbing removes 89 %., Proceedings of the 18th European Biomass Conference and Exhibition, 3-7 May 2010, Lyon, France, pp. 577-585

Experimental gasification campaigns were carried out at a bench scale facility based on a bubbling fluidized bed reactor to test residual biomass feedstocks. Aim of the work was to evaluate the effectiveness of a local dolomite as in-bed catalyst/sorbent towards the reduction of the tar and inorganic (e.g. H2S, HCl, NH3) contaminant load in the producer gas. Obtained results clearly showed the efficacy of the adopted dolomite material toward the reduction of tar and sour gas contaminants. Specifically, by testing low grade corn grit, among those considered, one of the biomass feedstocks with relatively high S and Cl content, reductions in the range 70.80 %-wt for H2S and 20.30 % for HCl were evaluated. Positive effect was also observed toward the tar content. Compared to tests carried out with olivine only, around 70 %-wt tar reduction was observed when an olivine/calcined-dolomite mixture was used. After tests, samples of used olivine and calcined-dolomite were collected and analyzed for XRD characterizations to assess changes occurred on the grains during the gasification process., Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 285-287

An advanced gasification process aiming at highly efficient and cost-effective CHP production via SOFC is being developed. Due to the demanding technical specifications of commercial SOFCs about the content of organic and inorganic contaminants, the use of both primary and secondary methods for gas conditioning was considered. The present work concerns the results collected to evaluate the effectiveness of in-bed additives under the gasification conditions of S/B 0.5, ER 0.25, Tgasif. 850 °C. As representative feedstocks, Olive Pomace and Refuse Derived Fuel were considered. Specifically, the tests were carried out at a bench scale bubbling fluidized bed reactor using a mix olivine/calcined-dolomite, 70:30 %-wt, as bed inventory and alkali-metal carbonates (Na2CO3, K2CO3) as additives for sour gases removal. Compared to olivine, the use of the mixed bed allowed a tar reduction of about 40 %-wt, based on the chromatographic data; a reduction up to 35 % and 45 %, by weight, was estimated on HCl with K2CO3 and Na2CO3, respectively. In the case of H2S the highest efficacy (> 90 %-wt) was associated to the capture effect of the calcined dolomite., Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 526-529

This paper quotes an overview of the UNIfHY project results regarding pure hydrogen production from biomass gasification. Tests with different gasification agents (steam/air/oxygen) and at different temperatures showed syngas yield from 1.1 to 1.7 Nm3dry/kg of dry biomass, hydrogen content from 20 to 40%-v dry, tars, particulate in the range of 10-20 g/Nm3dry, sulphur and chlorine compounds in the range of 50-90 ppmv, ammonia up to 1600 ppmv. Candle filters showed particulate removal efficiency higher than 99%-wt. A portable purification system (PPS) consisting in a ZnO guard bed reactor, a water gas shift reactor (WGS), compressor and gas upgrading unit (PSA) was designed and realized. The system was proven to be operable stably and continuously in experimental runs lasting more than 12 h. Hydrogen production at concentration of 99.99%-v was achieved with an H2 yield from PSA of 66.4%. Based on the data collected, UNIfHY can reach an economic production cost of 3-10 €/kg H2 (in the range 4.00-0.04 t H2/day, respectively) with low environmental impact (0.5-2.4 kg CO2/kg H2) but targets have to be different for decentralised (40% efficiency, 10 years lifetime, Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 992-999

Energy valorization via gasification of the solid residue (digestate) collected in a process of anaerobic digestion (AD) of blended fermentable feedstocks was considered. A rotary kiln reactor was adopted to collect data on the process performances when CO2, steam and mixes of them, were used as gasifying agents. Preliminary experimental campaigns were carried out at 800 °C by using a dried digestate having 64 %-wt volatile matter, 10 %-wt fixed carbon and 26 %-wt ash. Based on the total amount of supplied digestate, at the considered operating conditions, feedstock conversions in the range 59-63 %-wt, were achieved. By using the experimental data (i.e. amount of final residue, yield and heating values of the producer gas) in a simulation model of the gasification process, mass and energy balances were estimated. Among the different process conditions considered, the digestate gasification with preferable, although preliminary, operating conditions resulted that one carried out using only CO2 at a CO2/Feedstock ratio around 0.26 by weight. At this operating conditions, for the cold gas efficiency and the producer gas fraction to be used for covering the heat duty at the rotary kiln, values of 69 % and 28 % were respectively estimated. In all other considered conditions, the estimated values were found lower. Chance for process improvements are however predictable., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 435-438

Use of sorbents for sorption enhanced water gas shift (SEWGS) were considered to adjust the composition of the product gas obtained from a process of biomass gasification and convert it in BioSNG. To this purpose four sorbents were prepared and tested in experiments of SEWGS with a real gas obtained at a 1000 kWth pilot plant based on the process of steam/oxygen biomass gasification. The selected sorbents were two K-enriched hydrotalcites Mg/Al (HT1K and PMG70/K), a hydrocalumite Ca/Al (HT2) and a mixed hydrotalcite Mg/Ca/Al (HT3). The two Mg/Al materials were selected for cyclic tests of SEWGS at 400 °C (low temperature), the other two for evaluations at 600 °C (high temperature). Based on the experimental results, average and rather stable, CO2-uptake capacities of about 0.9 and 0.7 mmolCO2/gsorbent were respectively evaluated for HT1K and PMG70/K; for HT2 and HT3 the average uptake capacities were correspondingly found to be 2.6 and 3.1 mmolCO2/gsorbent. By comparing the structural properties of the materials before and after tests, no relevant modifications were observed based on results from SEM-EDX and XRD, as well as no presence of residual contaminants from tars were detected based on the FTIR spectrum. Preliminary data from modelling for the processes carried out at 400 °C and 600 °C, indicated a conversion efficiency from biomass to BioSNG up to 56 % and 45 %, respectively., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 478-484

Phenol is a major component in the scrubber wastewater used for syngas purification in biomass-based gasification plants. Adsorption is a common strategy for wastewater purification, and carbon materials, such as activated carbons and biochar, may be used for its remediation. In this work, we compare the adsorption behavior towards phenol of two biochar samples, produced by pyrolysis and gasification of lignocellulose biomass, with two commercial activated carbons. Obtained data were also used to assess the effect of textural properties (i.e., surface area) on phenol removal. Continuous tests in lab-scale columns were also carried out and the obtained data were processed with literature models in order to obtain design parameters for scale-up. Results clearly indicate the superiority of activated carbons due to the higher pore volume, although biomass-derived char may be more suitable from an economic and environmental point of view. The phenol adsorption capacity increases from about 65 m/g for gasification biochar to about 270 mg/g for the commercial activated carbon. Correspondingly, service time of commercial activated carbons was found to be about six times higher than that of gasification biochar. Finally, results indicate that phenol may be used as a model for characterizing the adsorption capacity of the investigated carbon materials, but in the case of real waste water the carbon usage rate should be considered at least 1.5 times higher than that calculated for phenol.

An innovative 1000 kWth pilot plant based on a bubbling fluidized bed gasifier with internal recirculation was operated in experimental campaigns of biomass gasification. The evaluations were focused on the gasifier performances and quality of the product gas. To this aim, tests were carried out at atmospheric pressure using almond shells as a feedstock and three defined gasification mediums (i.e. steam/O2 mixture, 35wt.% and 50wt.% O2 enriched air); process temperature was in the range 820-880 °C. The result assessment allowed to evaluate the system flexibility to the gasifying agent and acquire data on the gas producible with this specific configuration. Based on the dry compositions, LHVs in the range 5.9-6.7 MJ/Nm3 dry, 6.3-8.4 MJ/Nm3 dry and 10.9-11.7 MJ/Nm3 dry were respectively calculated for the three product gases. Correspondingly, an increase in the cold gas efficiency from 0.5 up to 0.7 was also estimated. Concerning the contaminant loads, in the case of the tests related to steam/O2 biomass gasification, particle and tar contents were found in the range 6-10 g/Nm3 dry and 12-18 g/Nm3 dry, respectively, while H2S, HCl and NH3 were at concentrations below 100 ppms (v). © 2015 Elsevier B.V. All rights reserved.

The aim of this work is to identify solid sorbents for CO2 capture for coal and biomass syngas conditioning and cleaning by means of a sorption-enhanced reaction process. Hydrotalcite-like compounds (HTlcs) were synthesized with and without K2CO3 impregnation. Samples were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) porosimetry after synthesis and after capture tests, respectively. Sorption and desorption tests were performed in a fluidized bed reactor, under cyclic conditions, at two different temperature levels: 350/450°C and 600/700°C. At low temperature only the Mg–Al HTlcs K promoted samples showed stability and sorption capacity comparable with literature values. On the other hand, results at high temperature indicate that the mixed Mg-Ca-Al HTlcs samples exhibit the best behavior with the highest sorption capacity (1.7 mmolCO2/g) almost stable over 5 sorption/regeneration cycles; furthermore, addition of steam allowed increasing their reactivity by 70% compared to the dry value. This type of sorbent could be a promising candidate to prepare a bifunctional sorbent–catalyst for sorption-enhanced processes, taking place directly in the fluidized bed gasifier, or downstream the reactor for adjustment of gas composition before further conversion in gaseous energy carriers.

It is under development a biomass gasification plant based on a 1 MW th bubbling fluidized bed (BFB) reactor with internal recirculation. Compared to conventional BFB design, the mechanism of internal circulation of solids can give beneficial effect to the process in terms of biomass conversion efficiency into gaseous product and gas quality. A model describing the process of biomass gasification in the two reaction chambers was developed. Expected results were preliminarily validated by experimental results obtained at a bench scale facility working on the same gasification concept. © 2013 The Authors.