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The Aran Valley in Catalonia (Spain) was the site of large-scale Zn, Pb, Cu, Fe, and Ag mining from the late 19th century until approximately 1950. Although mining activities ceased over 70 years ago, some of the abandoned mining relics (e.g. tunnels, processing facilities, and tailings dumps) exhibit elevated concentrations of metals in the associated water systems, thus posing a health risk in the neighboring ecosystem. In this study, the largest underground zinc mine in the Aran Valley (the Victoria Mine) was chosen as a field site to showcase the processes affecting metal mobility in the environment. Three sampling campaigns to the mine (2019, 2020 and 2021) provide a spaciotemporal dataset showing the evolution of solute concentrations through the system along a flow path. Rainwater from the upper catchment flows into the host rock above the mine, dissolving ore materials (primarily Zn (sphalerite) and Fe (pyrite) sulfides with Ni and Cd impurities) that cause elevated Zn, Ni, and Cd concentrations in the water that enters the mine. Precipitation of hydrozincite (Zn5(CO3)2(OH)6) along the gallery where water flows serves as a metal-removal mechanism resulting in significantly diminished metal concentrations (e.g. Zn from 155 to 10 ppm, Ni from 377 to 32 ppb, and Cd from 105 to 22 ppb). Characterization of the solid samples taken from the mine reveals several different morphologies, Zn zonations in hydrozincite (i.e. purity changes), and small amounts of smithsonite (ZnCO3) and calcite (CaCO3). In general, all solids show layering, which is a result of intermittent precipitation of distinct solid products. These precipitation patterns are likely a result of changing solute concentrations and precipitation rates. Variations in rain events change the water residence time in both the host rock and in the gallery, thereby altering the water composition. Solubility experiments and speciation calculations demonstrate that hydrozincite here does not have a constant Keq value, but rather a range of values (30.0 < log[Keq] < 37.68 at 7 °C). This behavior is presumed to be a result of precursor effects as amorphous solids with higher solubilities may form before the structured hydrozincite. Notably, all analyzed solids from the collected mine samples show significant amounts of amorphous material, demonstrated by broad XRD peaks along with significant impurities in the analyzed solids, leading to the hypothesis that there exists a variability in the solubility of hydrozincite beyond a pure end-member value., We would like to thank Jordi Bellés, Natàlia Moreno, Rafael Bartrolí and Mercè Cabanas (IDAEA), David Artiga, Maite Romero and Xavier LLovet (SCT-Barcelona University) for analytical assistance and Jordi Gavaldà (Conselh Generau d'Aran) for field assistance. This work has been financed by the CGL2017-82331-R project (Spanish Ministry of Economy and Competitiveness), with contribution of FEDER funds, and 2021 SGR 00308 project (Catalan Government). IDAEA-CSIC is a Centre of Excellence Severo Ochoa (Spanish Ministry of Science and Innovation, Project CEX2018-000794-S funded by MCIN/AEI/10.13039/501100011033). We are grateful to an anonymous reviewer and Editor, Stefano Albanese, for their insightful comments.

5 figures, 7 tables.-- Supplementary information available., The acid-free hydrothermal microwave–assisted selective scissoring (Hymass concept) of cellulosic substrates is gaining keen interest in the field of materials science. Besides, implementing catalytic methodologies to upgrade side streams produced during this process could contribute to better, holistic utilisation of the starting feedstock. This work depicts a zero-waste biorefinery concept based on cellulose defibrillation from almond hulls using various hydrotreatment technologies (hydrogenation and hydrodeoxygenation) for downstream processing on a ruthenium catalyst. Therein, the hemicellulose separated from the biomass preconditioning step was converted into sugar alcohols and/or marketable polyols with a relatively high yield (47.4%) by hydrolytic hydrogenation (437 K, 3h, 5.0 MPa H2). Meanwhile, a family of bioactive compounds (3-hydroxypyridines) could be directly extracted from the hydrolysate stream derived from microwave digestion, along with an energy carrier that was chemically stabilised (503 K, 60 min, 4.0 MPa H2) to obtain fuel additives (diethyl succinic acid, DES) and/or fuel intermediates., The authors are grateful for the financial support from the Spanish Ministry of Economy and Competitiveness (MINECO, Project ENE2017-83854-R) and the I+D+i project PID2020-115053RB-I00, funded by MCIN/AEI/10.13039/501100011033. J.R. is grateful to the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva Incorporación (JdC-I) fellowship (Grant Number: IJC2018-037110-I) awarded.

7 figures, 1 table.-- Supplementary information available. © 2023. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/, In this study, efficient electrodes for the hydrogen evolution reaction (HER) based on low-cost and metal-free carbon catalysts are presented. Phytic acid, a biosourced molecule containing carbon (C) and phosphorus (P), was found to be an excellent precursor for producing carbon materials with high P content, depending on the carbonization temperature, from 27.9 wt% at 700 °C to 7.3 wt% at 1000 °C. A green and easy route to produce P-doped carbon materials by heat treatment of this biosourced precursor without the need for additional reagents is thus proposed. We show that the conversion of P-O-type groups into P-C-type species is of paramount importance for improving the catalytic activity in HER of P-doped carbon materials. P-C-type groups appear to be the key factor in the electrocatalytic activity, reaching an onset potential of - 0.27 V. This study sheds light on the origin of the catalytic activity of P-doped carbons, in which P is expected to modify the homogenous distribution of the electron density of undoped carbons and increase their catalytic performance., This study was partially supported by the French PIA project “Lorraine Université d’Excellence”, reference ANR-15-IDEX-04-LUE, and the TALiSMAN and TALisMAN2 projects funded by ERDF. SGD thanks the Ministerio de Universidades, the European Union, and the University of Oviedo for the financial support (MU-21-UP2021-030 30267158). JQB thanks the Ministerio de Universidades, the European Union, and the University of Alicante for the financial support (MARSALAS21-21).

11 páginas, 3 tablas, 9 figuras, Biofuel potential of a widely grown perennial grass, Pennisetum polystachion, was analyzed using triethylammonium hydrogen sulfate ([TEA][HSO4]) pretreatment. The optimum pretreatment condition was selected based on the delignification efficiency. 80% [TEA][HSO4] at 140 °C for 45 min at 10% sample load, yielding high delignification rate (65.8%) was selected as the optimum pretreatment condition. Recycling of [TEA][HSO4] showed up to 90% IL recovery and significant delignification rates. Glucan yield in the biomass increased to 67.8%, whereas digestibility of biomass enhanced from 16.7% to 84.1%. Extensive deferuloylation (88%) and decoumarylation (86.4%) were observed in the sample following pretreatment. Diferulic acids were not detected in pretreated samples indicating their complete removal. HMF (0.1 mg/mL) and furfural (0.001 mg/mL) produced during pretreatment were very low compared to conventional methods. FTIR and XRD confirmed pronounced delignification and hemicellulose dissolution, and FESEM showed a marked difference in the surface morphology, including defibrillation and enhanced porosity. An ethanol yield of 275 mg/g biomass (84.7% of theoretical maxima) was achieved using Saccharomyces cerevisiae MTCC 36 after 15 h of fermentation. The results obtained from the current study can shed light on utilizing P. polystachion as a potential biofuel feedstock using a low-cost ionic liquid [TEA][HSO4]., The present study did not receive any specific grants from public, commercial or not-for-profit agencies.

12 figures, 3 tables.-- Supplementary information available., The use of bio-ethanol in chemical looping combustion (CLC) and reforming (CLR) has the potential to produce energy and/or hydrogen and, as a negative-emissions technology (NET), to remove CO2 from the atmosphere at low cost following the principles of bio-energy with CO2 capture and storage (BECCS). The determination of the rate of the chemical processes involving the fuel conversion with the oxygen carrier is required for the modelling and design of a chemical looping unit. In this work, a kinetic study of ethanol conversion is performed considering a NiO-based material as the oxygen carrier. Combined experiments in TGA and fixed bed were conducted. TGA tests confirmed that the oxygen carrier was reduced by a ethanol-containing gaseous stream at temperatures higher than 773 K. An apparent reaction kinetics for the NiO reduction with ethanol was determined, which might be used in simplified fuel reactor models. However, tests performed in a fixed bed revealed that products derived of the ethanol decomposition, such as CH4, CO, H2 were responsible for NiO reduction, instead of the direct reduction with ethanol. High temperature kinetics of processes involved in ethanol conversion, namely dehydration, dehydrogenation and decomposition, were determined. Both, non-catalytic and Ni-catalytic reactions were of relevance under chemical looping conditions. A reaction pathway was described to be used in detailed fuel reactor models of chemical looping units., This work was supported by Serviço Nacional de Aprendizagem Industrial, SENAI-DR/RN (Ref. 20194247).

7 figures, 6 tables., Biogas is a renewable fuel generated in the anaerobic digestion of organic material. The expansion of biogas as a bioenergy source in the next decades leads to find new ways for its energy exploitation such as the Chemical Looping technologies. In this work, a low-cost Fe-based residue was used as oxygen carrier in two processes with biogas, namely Chemical Looping Combustion (CLC) and Chemical Looping Reforming (CLR). CLC process is focused on the energy production with CO2 capture. CLC experiments showed higher methane combustion efficiency (∼86%) than those referred in literature with other low-cost Fe-based materials. CLR process is dedicated to the production of syngas or hydrogen without CO2 emissions. Ni- or Cu-based oxygen carrier had been successfully used in order to catalyse the methane reforming. Here, the Fe-based material was also used for CLR. The biogas composition facilitated dry reforming of biogas to obtain syngas. In the dry-CLR of biogas, it was possible to reach about 55% methane conversion with a yield to syngas of 1.3 mol (CO + H2)/mol CH4. A suitable management of the effluent gas is proposed to maximize CH4 conversion and syngas yield, which includes CO2 separation, H2 purification and CH4 recirculation. Both results confirm the potential of the energy use of biogas under these technologies and the promising results with the new oxygen carrier developed., This work was supported by Grant PID2020-113131RB-I00 funded by MICIN/AEI/10.13039/501100011033CO2SPLIT (CO2SPLIT project). [...]. A. Cabello also thanks the Grant IJC2019-038908_I funded by MCIN/AEI/10.13039/501100011033.

©2023. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/, This study presents a vanadium redox flow battery model that considers the most important variables that have a crucial role in the performance of the system. A complete model divided in an electrochemical, thermal, hydraulic and voltage submodels is presented. The analytic analysis of the model is carried out to reduce the system order according to some conservation laws. Based on this analysis, a subsequent calibration of the model parameters is developed using real experimental data. The validation is performed comparing the real measured voltage and the one estimated with the model. To calibrate the model an algorithm based on the implementation of a particle swarm optimizer is used. Results obtained in both short and long-term operation are presented, in order to compare and validate if the model can be used for both state of charge and state of health estimation., This research has been developed within the CSIC Interdisciplinary Thematic Platform (PTI+) Transición Energética Sostenible+ (PTI- TRANSENER+) as part of the CSIC program for the Spanish Recovery, Transformation and Resilience Plan funded by the Recovery and Re- silience Facility of the European Union, established by the Regulation (EU) 2020/2094, the Spanish Ministry of Science and Innovation under projects MAFALDA (PID2021-126001OB-C31 and C32 funded by MCIN/AEI/10.13039/501100011033/ERDF, EU), and MASHED, Spain (TED2021-129927B-I00), and by the Spanish Ministry of Universities funded by the European Union - NextGenerationEU (2022UPC-MSC- 93823).

11 figures, 3 tables.-- Supplementary information available., Carbon nanostructures provide a unique platform for the synthesis of novel catalysts for biomass conversion. In this work, a set of graphene oxide (GO)-based materials (nanofibers (GONF), sheets of few-layers (FLGO), and quantum dots (GOQD)), differing structurally in morphology and size, was prepared from fishbone-carbon nanofibers (CNF) and their catalytic behavior was compared on the hydrolysis of amorphous cellulose under microwave (MW) radiation. First, the influence of the reaction temperature (135–180 ºC), holding time (0–120 min), catalyst morphology and cellulose/water ratio (0.25–2.0 wt%) was thoroughly screened and compared with conventional heating mode. The use of GO morphologies in concert with MW energy showed the potential to achieve similar kinetic profiles than previously reported sulfonated carbons (110 kJ/mol) but using considerably less amount of catalyst (cellulose-to-catalyst ratio 12-fold lower). Overall, the reactivity of the GO-catalyst was related to their degree of oxidation/exfoliation, decreasing as follows: GOQD > FLGO > GONF. Compared with conventional heating, MW-technology enabled higher loadings of cellulose (2.0 vs. 0.25 wt%) to be processed in a shorter time (20 min instead of 24 h), which is a landmark achievement toward process intensification., The authors are grateful for the financial support from the Spanish Ministry of Economy and Competitiveness (MINECO, Project ENE2017–83854-R) and the I+D+i project PID2020–115053RB-I00, funded by MCIN/ AEI/10.13039/501100011033. E.F. also thanks Ibercaja bank entity for a grant-in-aid for foreign research stays (CB 7/19). J.R. is grateful to the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva Incorporación (JdC-I) fellowship (Grant Number: IJC2018–037110-I) awarded. DT is grateful for the Juan de la Cierva Incorporación (JdC-I) fellowship (Grant Number: IJC2020–045553-I) funded by MCIN/AEI/ 10.13039/501100011033 and by “European Union NextGenerationEU/PRTR”.

[EN] Very small-sized shoots of the Mediterranean seagrass Posidonia oceanica, defined as “bonsai” shoots, were found in areas with most intense CO2 emissions and low pH associated with four vents systems off Panarea island (Aeolian Archipelago, Sicily, Southern Tyrrhenian Sea). Bonsai shoots were sampled in September 2021 and October 2022: Bottaro crater (8 m depth), Camp 7 (16 m and 21 m), Black Point (20 m) and Hot/Cold Points (10 m). They had 2–6 leaves, and adult-intermediate leaves were 5–21 cm long and 3.5–7 mm wide, with leaf shoot surface ranging 4.8 and 44.5 cm2, and shoot leaf biomass between 16 and 89 mg (d.w.). These values were all significantly lower (t-test p < 0.006–0.0001) than those measured in normal-sized shoots collected within the vents and in control sites not affected by gas emissions. Bonsai shoots had 86–89% lower leaf surface, and 61–75% lower leaf biomass than all normal-sized shoots measured. The sheath thickness of the bonsai shoots was very low (0.1–0.8 mm), and the temporal trend of sheath thickness along the rhizome (lepidochronology) showed an irregular pattern, without the clear cyclical seasonal variation typical of normal-sized shoots. The reasons of size reduction and lack of temporal cycle in lepidochronology are discussed in the light of plant acclimatization and the constraints imposed by the continuous exposure to the stressful conditions of seawater acidification and presence of phytotoxic gases (e.g. hydrogen sulfide) in the vents., We wish to thank the staff of the 5th and 6th School of scientific diving at Panarea (2021–2022) and the 2nd stage on Posidonia oceanica ecology at Salina (2022; founded by the Blue Marine Foundation), as well as the diving Amphibia coordinated by Andrea Fogliuzzi, for the support at sea and in the laboratory. Thanks to the ECCSEL NatLab Italy infrastructure of the OGS for the logistic support at Panarea. We wish to thank the anonymous reviewers, and the Editor B. van Tussenbroek, for the useful and constructive comments.

13 figures, 4 tables., Chemical Looping with Oxygen Uncoupling (CLOU) is a technological adaptation of CLC, most applicable for the combustion of solid fuels. In the CLOU process, an oxygen carrier in the fuel reactor, avoiding the direct contact of the fuel with the air, releases the oxygen needed for the fuel combustion. The oxygen carrier is regenerated with air in the interconnected air reactor. The present work explores the behavior of the system Mn/Mg/Si as oxygen carriers for chemical-looping with oxygen uncoupling (CLOU). Six different mixed oxides of the system Mn/Mg/Si were investigated for the CLC/CLOU process. Materials were prepared by spray drying with different metal ratios used in the investigation. The properties of interest for the viability of these materials are the lattice oxygen supply for CLC and the gaseous oxygen release for CLOU, properties that were explored in a TGA. Further, the fluidization behavior and the mechanical resistance were investigated in a batch fluidized bed reactor. In the TGA it was observed that the most reactive oxygen carriers for the CLOU process were materials without Si in the structure, more specifically M24Mg76 and M48Mg51 which had a molar ratio of Mn/Mg of 0.17 and 0.51 respectively. It was also observed that for the oxygen carriers with Si in the composition, the regeneration was very poor. Oxygen carriers M24Mg76 and M48Mg51 were selected for batch fluidized bed reactor testing showing good behavior with respect to the CLOU reactivity, and mechanical stability. One of the materials, the M24Mg76 showed activation during the experiments in the batch fluidized bed reactor experiments, increasing the oxygen transport capacity by 20 % during the experiment. However, 10 vol% of O2 was needed to regenerate both oxygen carriers at 850 °C. No agglomeration tendencies were seen, and the attrition rate was low, obtaining high-extrapolated lifetime values. The fact that highly reactive oxygen carriers can be made with cheap and highly available metals oxides, i.e. Mn and Mg, makes this system very promising and a possible alternative to benchmark Cu-based CLOU materials., The work presented in this article is partially funded by the Spanish Research Council (CSIC) through the Intramural Project (201980E043). I. Adánez-Rubio acknowledges for “Juan de la Cierva” Program (Grant IJC2019-038987-I funded by MCIN/AEI/10.13039/501100011033). The work was also supported by Chalmers Energy Area of Advance.

5 figures, 2 tables., Chemical Looping Combustion (CLC) is a low-cost CO2 capture technology highly competitive for industrial and energy applications. Up to date, CLC has been mostly developed at atmospheric pressure. Pressurized CLC may bring additional advantages due to the intensification of the process. The main objective of this work was to determine whether an increase in the operating pressure could improve the fuel conversion in CLC systems of gaseous fuels when ilmenite was used as oxygen carrier. Fluid dynamics considerations were evaluated to determine a window of suitable design parameters at pressurized conditions. A theoretical model previously validated at atmospheric pressure was modified to consider fluid dynamics and reaction kinetics at pressurized conditions, both in the bubbling and turbulent regimes, using ilmenite as oxygen carrier. The conversion of natural gas was estimated as a function of several design and operating parameters, such as the gas velocity, particle size and reacting temperature. Uncompleted combustion of natural gas was predicted at atmospheric conditions, and a limited improvement was estimated at pressurized conditions. A discussion about the required reactivity of the oxygen carrier to achieve complete combustion was performed. Furthermore, an energy analysis of a CLC system operating at atmospheric or pressurized (0.5 MPa) conditions with fuel reactor designed under the bubbling or turbulent regimes was carried out using the Aspen HYSYS process simulation software for two different applications of heat generation: production of domestic hot water and process steam. From this energy balance, it could be concluded that the energy efficiency achieved at pressurized conditions was slightly higher than that obtained at atmospheric pressure, essentially because at pressurized conditions it was possible to use the latent heat of condensation of the water generated in the fuel reactor. In addition to the results obtained in this work, a thorough assessment of technical risks and a techno-economic analysis would be required in order to make a final decision about the feasibility of operating at pressurized conditions in CLC systems., This work was supported by the project I-LINK1225 from the i-Link + 2017 program (CSIC) and the GTCLC-NEG project that has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 101018756. A. Cabello also thanks the Grant IJC2019-038908-I funded by MCIN/AEI/10.13039/501100011033.

13 figures, 5 tables.-- Appendix A. The impact of recovery rate on the DSPRO net pressure difference.-- © 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/, Two-pass reverse osmosis desalination is a common process to treat high-salinity feed solution and provides a low-salinity permeate solution. This study investigated the significance of the energy generated by the dual-stage pressure retarded osmosis (DSPRO) from the reverse osmosis (RO) brine stream. The main components of the DSPRO-RO hybrid system are RO, pressure retarded osmosis (PRO), and energy recovery device, and their models are determined. Dymola software, using Modelica modelling language, was utilized for solving the hybrid system models. Two different flowsheets were built; the first included a two-pass RO, while the second is a hybrid of a two-pass RO (2RO)-DSPRO system. Seawater salinities of 40 and 45 g/L were the RO feed solution, and 1 g/L tertiary treated wastewater was the feed solution of the DSPRO process. The net specific energy consumption was calculated for the 2RO and 2RO-DSPRO systems for 40 and 45 g/L salinities. At a 47 % recovery rate and 40 g/L seawater salinity, the 2RO-DSPRO system was 14.7 % more energy efficient than the 2RO system. The corresponding energy saving at a 47 % recovery rate and 45 g/L seawater salinity was 17.5 %. The desalination energy for the 2RO system was between 3.25 and 3.49 kWh/m3, and for the 2RO-DSPRO system was between 2.91 and 2.97 kWh/m3. The results demonstrate the great potential of integrating the 2RO with the DSPRO to reduce desalination's energy consumption and environmental impacts., The authors wish to express their gratitude for the assistance provided by an Australian Government Research Training Program Scholarship. The RO-PRO pilot plant data used in this project was collected as part of the ongoing technology development project titled “Membrane-based efficient energy storage, clean energy generation, and wastewater treatment system”. This project is supported by the Department of Science and Technology, Government of India, Project Number No. DST/TMIWTI/2K16/73 (G).

8 figures, 4 tables., Considerable amounts of expired food waste are generated every day. They are rich in organic carbon and in other elements, including nitrogen, phosphorus and potassium, which cannot be wasted. The present work tested expired food waste in terms of biogas production efficiency in anaerobic digestion (AD) process. A database was extrapolated from the tests carried out in order to obtain a complete list of physico-chemical and biochemical methane potential (BMP) of 88 expired food waste. Many studies are based on the analysis of a small number of samples, which are don't present a complete picture of all the types of food waste. The organic composition and other factors such as pH, temperature, C/N ratio of the samples varies considerably with the region, the season and the processing characteristics, resulting in methane yield variations, ranging from 216 to 1476 mL CH4/gVS. Therefore, knowledge of the appropriate physical and chemical properties of the feedstock, working conditions and the effects of the inhibition of various components on the anaerobic digestion processes is a key element, necessary to optimize energy production from food waste., This research is part of the LIFE16ENV/IT/OOO574 i-REXFO project funded by the EU under the LIFE 2016 program and the database is a deliverable of the project i-REXFO (http://irexfo.eu)

11 Pág. Centro de Biotecnología y Genómica de Plantas, Protein synthesis is a fundamental process for life and, as such, plays a crucial role in the adaptation to energy, developmentaland environmental conditions. For these reasons, and despite the general conservation of the eukaryotic translational machinery, it is not surprising that organisms with different lifestyles have evolved distinct mechanisms of regulation to adapt translation initiation to their intrinsic growth and development. Plants have clear peculiarities compared with other eukaryotes that have also extended to translation control. This review describes the plant-specific mechanisms for regulation of translation initiation, with a focus on those that modulate the eIF4F complexes, central translational regulatory hubs in all eukaryotes, and highlights the latest discoveries on the signaling pathways that regulate their constituents and activity., Our research related to translation is supported by Grants S2013-ABI2734 (CAM, Spain) and RTI2018-095946-Our research related to translation is supported by Grants S2013-ABI2734 (CAM, Spain) and RTI2018-095946-B100 (MICIU, Spain) to M.M.C. and Grants BIO2017-82720-P and RYC2017-22323 (MINECO, Spain) and P18-RT-1218 (Junta de Andalucía, Spain) to C.M.

9 figures, 3 tables.-- Supplementary information available., In this work, the Biomass Chemical Looping Gasification (BCLG) process was evaluated for syngas production at the 20 kWth scale using wheat straw pellets as the fuel feedstock and ilmenite as the oxygen carrier. The effect of different operational variables –namely the fuel reactor temperature, the mean residence time of solids in the fuel reactor, the oxygen-to-biomass ratio (controlled by the oxygen fed into the air reactor) and the gas velocity in the carbon stripper– on the process performance and the syngas yield was analyzed. Interestingly, smooth operation of the CLG unit was observed and no agglomeration issues detected. In addition, char produced during devolatilization still retained its initial pellet shape and unconverted char pellets were elutriated from the fuel reactor mixed with the finer oxygen carrier particles. Both steady-state and transition periods were evaluated to have a complete overview of the process. Transition periods were characterized by a different oxygen transfer rate in the air and fuel reactors. Steady state was reached when the oxygen transference rate was the same in both reactors. In this sense, the oxygen transference rate in the fuel reactor was the main factor affecting the syngas yield and the cold gas efficiency. Also, the temperature and mean residence time of solids in the fuel reactor showed a considerable effect on the char conversion and, consequently, on the syngas yield. However, operating conditions hardly affected the production of light hydrocarbons (CH4 and C2-C3) and tar, which were maintained roughly constant throughout the experimental campaign., This work has been carried out in the framework of the European Union's Horizon 2020 – Research and Innovation Framework Programme under grant agreement No 817841 (Chemical Looping gsification foR sustainAble production of biofuels – CLARA), and by the AEI/FEDER, UE (ENE2017-89473R).