Acacia mearnsii, an invasive alien species, is the main resource identified for the energy transition initiated on Reunion Island. It is, therefore, critical to identify the existent forest stands within the island’s large tropical forest area and to determine which of these stands are accessible for logging operations. In this study, a very high-spatial-resolution image was used to map forest (Acacia mearnsii, Acacia heterophylla, Cryptomeria japonica) and non-forest land cover. To identify the accessible forest stands, we developed a geographic information system (GIS) processing chain, accounting for barriers, the distribution of slopes, and the location of forest roads. User-defined parameters, such as the slope threshold and maximal distance to forest roads, allow different scenarios to be explored. The classification yields an overall accuracy of 88% and a Kappa index of 0.86 and highlights the areas occupied by the different types of Acacia. By applying the GIS processing chain for a standard scenario, the results show that only 19% of the initial study area of 637 ha of Acacia mearnsii patches is suitable for exploitation. In conclusion, our results demonstrate how remote sensing (RS) and GIS can be combined to provide valuable tools for forest managers to design management plans for invasive alien forest species.

Reunion Island, a French overseas region in the Indian Ocean, has endorsed policies targeting food and electricity self-sufficiency. This objective implies balancing different land-uses (food, feed, bioelectricity, urbanisation, etc.) which we explore in a set of scenarios towards 2035. Through participatory structural analysis, we modelled drivers of change as processes using Ocelet, a spatially explicit and dynamic modelling platform. We built a detailed land-use map for our initial state and calibrated relevant processes through four scenarios ranging from "business-as-usual" to "implementation of ambitious territory planning policies". To improve local self-sufficiency, our results support the need for large-scale land planning policies, suggesting partial sugarcane conversion into food crops, urbanisation control, farmlands expansion onto fallows and photovoltaic increase. Our context-specific approach addresses food and electricity self-sufficiency as a whole and understands its inner dynamic and spatial processes from stakeholders' viewpoint. Moreover, our model recognizes small-scale spatial heterogeneity and contributes to mediate controversial issues related to territory foresight and land-use planning.

Dans le monde, le pétrole assure 96 % des besoins des transports, lesquels mobilisent 65 % du pétrole consommé et participent à hauteur de 20 % aux émissions de CO 2 . Afin de réduire la consommation de ressources fossiles, une des alternatives est notamment l’utilisation de « biocarburants ». Ces biocarburants sont classés en trois générations successives. Les biocarburants de première génération sont issus des parties alimentaires de plantes de grande culture : le bioéthanol et le biodiesel. Les biocarburants dits « avancés » de seconde génération sont issus de ressources lignocellulosiques (bois, résidus agricoles...) valorisées soit en bioéthanol soit en hydrocarbures de synthèse. Une troisième génération repose sur la culture de micro-algues productrices d’acides gras transformés en biodiesel. Les biodiesels de première génération, tout comme ceux de deuxième et troisième générations, sont sujets à certaines critiques notamment le CAS (changement d’affectation des sols) et la compétition alimentaire/énergétique. L’objectif de ce travail est d’examiner l’intérêt de deux filières prometteuses. Les biodiesels basés sur des cultures dédiées conduisent à des impacts environnementaux plus réduits mais jouent un rôle dans la problématique des CAS. Alors que celles basées sur les résidus n’y entrent pas et montrent des niveaux de réduction des émissions de gaz à effet de serre entre 83 et 90 % contre 60 à 80 % pour un biodiesel classique par rapport à un carburant diesel fossile. Les esters butyliques d’huiles alimentaires usagées et de graisses animales s’affichent comme des biodiesels « plus verts » et représentent une opportunité pour les biocarburants de deuxième génération et pour une oléochimie « plus verte ».

In the world, oil provides 96% of transport needs, which mobilize 65% of the oil consumed and contribute 20% to CO2 emissions. One of the alternatives to reduce the consumption of fossil resources is the use of "biofuels". These biofuels are classified into three successive generations. The first generation biofuels come from the food parts of field crops: bioethanol and biodiesel. Second generation "advanced" biofuels come from lignocellulosic resources (wood, agricultural residues, etc.) valued either as bioethanol or synthetic hydrocarbons. A third generation is based on the culture of micro-algae producing fatty acids transformed into biodiesel. The first generation biodiesels, like those of the second and third generations, are subject to certain criticisms in particular the LUC (Land-Use Change) and the food versus energy competition. The objective of this work is to examine the interest of two promising ways. Biodiesel based on dedicated crops lead to reduced environmental impacts but play a role in the problem of LUC. While those based on residues are not part of the problem and show levels of reduction of greenhouse gas emissions between 83 and 90% against 60 to 80% for a conventional biodiesel compared to a fossil diesel fuel. Butyl esters of used edible oils and animal fats are displayed as "greener" biodiesels and represent an opportunity for second generation biofuels and for a greener oleochemistry.

A rapid method was developed to characterize the Pyrolytic Lignin (PL) fraction of flash pyrolysis bio-oils, based on size exclusion chromatography (SEC) coupled to differential refractive index (DRI) and multi-angle laser light scattering (MALS) detectors. Two beech wood bio-oils with different PL content were used in the study. The first was produced with a single-stage condensation system (BO), while the second was an organic fraction collected in the first stage of a two-stage condensation system (F1). PL was isolated from both the BO and F1 bio-oils by the water precipitation method. Our results suggested that quantification of the pyrolytic lignin fraction of biooils can be performed by the SEC-MALS-DRI method provided that the specific refractive index increment (dn/dc) is known, and the integration interval is carefully chosen. Average molar mass (M-n) values for the BO and F1 samples were 580 +/- 50 Da and 890 +/- 50 Da, respectively. Our results indicated that the condensation system and the water precipitation method affect the average molar mass of isolated PL oligomers.

Catalytic deoxygenation of pyrolytic vapors represents a great challenge to produce biofuels by flash pyrolysis of lignocellulosic biomass. A wide variety of catalysts, particularly zeolites, have been investigated for this purpose, however, quick deactivation was often reported. Although they are cheap and can have a hierarchical pore structure, activated charcoal-based catalysts have received only little attention. This paper presents an innovative method to synthesize activated charcoal based catalysts doped with CeO2, Fe2O3 or Mn3O4 nanoparticles. We investigated the performances of those catalysts to deoxygenate two biomass pyrolytic model compounds - acetic acid and guaiacol - on a fixed-bed reactor between 350 degrees C and 450 degrees C. Ceria-based catalyst was highly active and remarkably stable to enhance ketonic decarboxylation of acetic acid, leading to the formation of acetone. Huge amounts of produced phenol attest for the partial deoxygenation of guaiacol, particularly when using iron-based catalyst. This study demonstrates the potential of activated charcoal-based catalysts to produce weak-acidic and partially deoxygenated bio-oils. (C) 2017 Elsevier B.V. All rights reserved.

Ex situ hot gas filtration (HGF) has been shown to be a simple and robust technique to upgrade the quality of flash pyrolysis oils. In this study, the secondary reactions inside the HGF unit and their impact on product yields and the chemical composition of bio-oils were investigated in a total of 18 experiments conducted at both pilot and bench reactor scales (1 and 0.1 kg/h), with beech wood (BW) and sunflower stalks (SFS). The impact of HGF on yields was found to be dependent on the extent of secondary reactions which, in turn, were determined by three parameters: (a) HGF temperature, (b) HGF char cake thickness, and (c) AAEM content of the raw feedstock. Nevertheless, independently of the conditions used, the drop in the organic yield was less than 10 wt % with both BW and SFS feedstocks. Our results demonstrated that (1) cracking reactions mainly took place in the homogeneous gas phase and (2) dehydration, coking, and decarboxylation reactions took place in the HGF char cake, probably catalyzed by the high AAEM content and the small size of the HGF char particles. Based on detailed chemical analysis of bio-oils, we propose several secondary reaction pathways to explain the interaction between the HGF char and the pyrolysis vapors, such as (1) ketonization of low Mw carboxyl functions via decarboxylation, (2) the formation of simple anhydro sugars by the selective cleavage of the glycosidic bond of the carbohydrate oligomers, and (3) the depolymerization of lignin oligomers. Further, our results suggest the interdependence of two factors which determine the impact of HGF: (a) the physical and chemical properties of HGF char and (b) the reactivity of the vapors.

The catalytic steam reforming of four different aqueous fractions of bio-oil has been carried out in a fixed bed reactor at 650 °C and atmospheric pressure using a Ni–Co/Al–Mg catalyst, employing a spatial time of 4 g catalyst min/g organics. The chemical analysis of the aqueous fractions revealed that the source of biomass (pine or poplar sawdust) and the pyrolysis unit significantly influenced the chemical composition of these liquids. Depending on their chemical composition, the initial H2 yield varied from 0.101 to 0.182 g H2/g organics and the initial CO2 yield from 0.814 to 1.28 g CO2/g organics during their catalytic reforming. Regarding catalytic stability, higher catalyst deactivation took place during the reforming of the two pine bio-oil aqueous fractions. The reforming results of the four aqueous fractions have been correlated to their chemical compositions using statistical empirical additive models developed using the Bayesian Information Criterion (BIC). This strategy enabled the identification of the chemical compounds responsible for the most significant variations observed during the reforming of the liquids. The different proportions of acetic acid and furfural in the liquids had the greatest impact on the reforming results. Acetic acid was identified as a compound with low reactivity and low coke formation. In contrast, furfural was found to have high reactivity and a high tendency to produce coke in the reforming process. Additional reforming experiments conducted with acetic acid, phenol, furfural, levoglucosan and guaiacol helped to confirm and explain the results obtained during the catalytic steam reforming of the aqueous fractions.

In this study an analytical multi-technique approach was developed in order to describe as fully as possible the composition of several fast pyrolysis oils. Six bio-oils were produced at CIRAD (centre de Cooperation Internationale en Recherche Agronomique pour le Developpement) and TI (Thunen Institute of Wood Research) using the same three lignocellulosic biomass materials (i.e. hardwood, softwood and wheat straw). Different and complementary analytical tools were used to characterize these samples. Whole bio-oils were first directly analyzed by gas chromatographic (GC) hyphenated techniques with flame ionization detector (FID) and mass spectrometry (MS) (Headspace-GC-FID/MS, GC-FID/MS) and by a high resolution mass spectrometry technique (Fourier transform ion cyclotron resonance mass spectrometry FT-ICR/MS) without any pre-separation step. The GC analyses provide a detailed molecular description (more than 90 compounds) of the composition of the six bio-oils. To achieve a better understanding of the chemical composition of this set of bio-oils, the samples were fractionated into aqueous fractions and water-insoluble fractions (also called pyrolytic lignins). Detailed analysis of sugars was performed by GC-FID/MS after a solid-phase extraction (SPE) and a subsequent derivatization performed on the aqueous fractions. Moreover, FT-ICR/MS analyses show that species having molecular weights up to 900 Da are present in the aqueous phases. The originality of this work is based on the development of complementary analytical tools (i.e., chromatographic and spectrometric techniques) to describe the composition from volatiles (monomeric) to non-volatiles (oligomeric) species of several bio-oils that were produced and stored under controlled conditions. (C) 2015 Elsevier B.V. All rights reserved.

An extensive characterization was carried out on various biomass samples representative of the diversity in France, including forestry samples (softwood and hardwood woodchips, eucalyptus and poplar short rotation coppices), very short rotation coppices (VSRC) samples and agricultural samples (wheat straw, triticale, fescue, miscanthus and switchgrass). The following properties were measured to evaluate suitability with thermochemical process: elemental analysis (C, H, O, N, S, and Cl), chemical composition (extractives, lignin, mono/polysaccharides, acetate groups), ash content and inorganic composition. Carbon and hydrogen contents are quite similar between biomasses. Agricultural biomasses are usually less oxygenated than forestry biomasses. Nitrogen content is generally higher for agricultural biomasses (up to 1.4 %) than for forestry biomasses, but important amount is also found in VSRC (0.8 % for poplar). Chlorine and sulfur are species-dependent. Fescue and eucalyptus show high values of Cl, while wheat straw has the highest sulfur content. Ash content is very low for forestry and perennial biomasses (miscanthus and switchgrass). For non-perennial crops, values up to 8.5 % (wheat straw) were measured. Agricultural biomasses contains more silicon (2 % for triticale), magnesium (0.16 % for fescue), potassium (1.9 % for fescue) and phosphorus (0.18 % for fescue), while forestry biomasses are richer in calcium (up to 0.97 % for poplar VSRC). Other inorganic elements, especially heavy metals are present in very low concentrations and most of the time below detection limits. Regarding chemical composition, extractive content is very high (20–25 %) for non-perennial crops (fescue, wheat straw and triticale) and eucalyptus VSRC. Lignin content seems to be higher for forestry biomasses (21–29 %) than for agricultural biomasses (16–23 %). The same trend was observed for cellulose, while the opposite was observed for hemicelluloses. These differences in organic and inorganic composition are expected to significantly impact the behavior of these biomasses in thermochemical processes such as gasification for biofuels production.

Catalytic pyrolysis is a promising way to improve bio-oil product quality. In this study, metal salts were directly impregnated in biomass to generate in situ catalysts and investigate their impact on pyrolysis products. Seven metals - Ce, Mn, Fe, Co, Ni, Cu and Zn - were selected and impregnated in eucalyptus using nitrate salts. A fixed-bed reactor, pre-heated at 500 degrees C and inerted with N-2 flow, was used for pyrolysis. Both gas and bio-oil compositions were analysed, paying particular attention to the production of anhydrosugars. The anhydrosugar yields were found to be strongly influenced by the presence of metal salt catalysts. In particular, both Zn and Co salts yielded more anhydrosugars in comparison with catalyst-free sample. Moreover, LAC (1-hydroxy-(1R)-3,6-dioxabicyclo[3.2.1]octan-2-one) was produced in higher amounts than levoglucosan which is commonly produced without any catalyst. Metals were found to remain in all chars and tended to form metal-based nanoparticles (e.g. Cu-0, Ni-0, ZnO) able to act as in situ catalysts during the pyrolysis process. It seems that those metal nanoparticles are closely related to LAC production. In parallel to metal cations, nitrates were also suspected to play a significant role during pyrolysis. The suspected impact of anions on levoglucosenone production is discussed. Concerning gas yields, the impregnated nitrate salts were found to strongly affect CO2 production. (C) 2014 Elsevier B.V. All rights reserved.

The aim of the present work is to produce hydrogen from biomass through bio-oil. Two possible upgrading routes are compared: catalytic and non-catalytic steam reforming of bio-oils. The main originality of the paper is to cover all the steps involved in both routes: the fast pyrolysis step to produce the bio-oils, the water extraction for obtaining the bio-oil aqueous fractions and the final steam reforming of the liquids. Two reactors were used in the first pyrolysis step to produce bio-oils from the same wood feedstock: a fluidized bed and a spouted bed. The mass balances and the compositions of both batches of bio-oils and aqueous fractions were in good agreement between both processes. Carboxylic acids, alcohols, aldehydes, ketones, furans, sugars and aromatics were the main compounds detected and quantified. In the steam reforming experiments, catalytic and non-catalytic processes were tested and compared to produce a hydrogen-rich gas from the bio-oils and the aqueous fractions. Moreover, two different catalytic reactors were tested in the catalytic process (a fixed and a fluidized bed). Under the experimental conditions tested, the H-2 yields were as follows: catalytic steam reforming of the aqueous fractions in fixed bed (0.17 g H-2/g organics) > non-catalytic steam reforming of the bio-oils (0.14 g H-2/g organics) > non-catalytic steam reforming of the aqueous fractions (0.13 g H-2/g organics) > catalytic steam reforming of the aqueous fractions in fluidized bed (0.07 g H-2/g organics). These different H-2 yields are a consequence of the different temperatures used in the reforming processes (650 degrees C and 1400 degrees C for the catalytic and the non-catalytic, respectively) as well as the high spatial velocity employed in the catalytic tests, which was not sufficiently low to reach equilibrium in the fluidized bed reactor. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

The sub-Saharan region of West Africa has a lack of natural resources, especially for energy producing. Agroalimentary biomasses like residues from nut processing and vegetable oil producing industries are so far unexploited concerning their potential application as fuel. This study explores the usability of cashew nut shells, jatropha and shea nut presscakes in energetic terms. In contrast to lignocellulosic biomass these residues are rich in extractives. The feedstocks were characterised in a first step upon their physical and chemical properties before they were pyrolysed in a thermogravimetric system and a tubular reactor under rapid pyrolysis conditions. This approach revealed the influence of extractives on decomposition behaviour and conversion. A detailed study of obtained pyrolysis oils showed that the extractives of cashew nut shells are not entirely cracked while vegetable oils decompose almost entirely. Jatropha oil is more unstable than shea butter. Rubber wood was chosen as a reference feedstock for further comparison with extractive rich biomasses. (C) 2013 Elsevier B.V. All rights reserved.

Le principal atout des biocarburants de seconde generation tient au fait que leurs procedes dobtention doivent permettre de convertir l'integralite de la biomasse. La competition entre usage alimentaire et non alimentaire des produits agricoles est limitee. La plante complete est valorisee ; a terme, une valorisation de nombreux residus et dechets organiques peut meme etre envisagee y compris pour la synthese de nombreux produits chimiques et de molecules plateformes, precurseur de nombreuses applications chimiques.

Short rotation forestry (SRF) is a promising feedstock for production of biofuels via the thermochemical route. Five poplar biomasses (SRF of different clones and ages, and debarked wood) were ground and separated into three particle size fractions: <0.2 mm; 0.2-0.4 mm; >0.4 mm. The characterization of these samples was performed to evaluate the quality and homogeneity of SRF feedstocks. Some major properties related to thermochemical processes were measured: chemical composition, organic and inorganic elemental compositions. The heterogeneity in SRF feedstock properties, resulting from high bark content, appeared to be transferred to particle size fractions. The results obtained highlighted that fine particles below 0.2 mm had very specific properties, close to those of bark. The removal of this fraction would result in a more homogeneous feedstock, avoiding the issue caused by segregation risk for process stability. Such removal of small particles would also modify the biomass properties by reducing bark amount, improving the suitability of SRF feedstock for thermochemical conversion. (C) 2013 Elsevier Ltd. All rights reserved.

Short rotation forestry (SRF) is a promising feedstock for biofuel production via thermochemical processes. This feedstock is highly heterogeneous, that could be problematic in case of segregation of ground samples. In order to assess an eventual segregation impact on biomass properties and potential consequences on thermochemical processes, 4 French poplar SRF sawdust feedstocks were sieved to particle size fractions ( 0.4mm). Important properties (in regard to thermochemical processes) were measured on those fractions: lignocellulosic composition, ash content, and elemental composition of organic and inorganic fractions. Significant differences between particle size fractions could be observed on lignocellulosic composition, ash content and inorganic composition. Cellulose content increased with particle size while lignin content was higher in small particles. Ash content was ranging 1-4%w in the biggest particles and 7-10%w in the smallest ones. Important differences could also be observed on major inorganic elements such as Ca and K, which are known to impact the gasification processes. This study shows that segregation may have significant impact on SRF chemical properties. The differences found on lignocellulosic composition, ash content and inorganic composition seemed high enough to have an effect on biomass conversion in thermochemical processes. Therefore, attention must be paid in sampling SRF biomass for analytical purposes, and in process control. According to the observations carried out, the smallest particles of ground SRF could be removed from biomass feedstock to adjust some biomass thermochemical behavior. This fraction could then be used for other applications such as return to soil or green chemistry. (Resume d'auteur)

In this study, pyrolysis process of wood bio-oil was studied. The effects of temperature in the range 550-1000 degrees C, heating rate in the range 2-2000 degrees C s(-1) and ash content of the bio-oil on char, tar and gas yields were investigated. The main gas species generated are quantified by Micro-GC: H-2, CO, CO2, CH4 and trace amounts of C2H4 and C2H6.A temperature increase from 550 to 1000 degrees C enhanced greatly the gas yield, whilst solid and liquid yields decreased significantly. The heating rate was varied in a range covering rapid pyrolysis using the Horizontal Tubular Reactor (HTR) to flash pyrolysis using an Entrained Flow Reactor (EFR). A decrease of char yield from 11 wt.% down to 4 wt.% was observed when heating rate is changed from 2 to 100 degrees C s(-1). In EFR a flash heating rate of 2000 degrees C s(-1) led to a char yield as low as 1 wt.%.Bio-oil with a natural ash contents of 0.05 wt.% and bio-oil added with 3 wt.% of ash were finally pyrolyzed. Ash seems to favor re-polymerization reactions that lead to an increase in char yield. A decrease in the amount of gas is observed when ash is added while an increase was a priori expected. (C) 2012 Elsevier Ltd. All rights reserved.

Biomass gasification is gaining attention as a route for biomass energy production. When large scale units are considered, bio-oil shows lots of advantages compared to solid biomass such as high energy volume density and easy handling and storing. Syngas (H-2 and CO) can be produced from bio-oil by two gasification processes, also called reforming processes: catalytic reforming at medium temperature and noncatalytic reforming at high temperature. In the literature, most of the works focus on the catalytic reforming and mainly concern the aqueous fraction of bio-oil or model compounds. Only very few works can be found on the noncatalytic reforming of crude bio-oil. The objectives of this work were to perform experimentally the injection and gasification of nondiluted bio-oil in a lab-scale High Temperature Entrained Flow Reactor (HT-EFR) and to determine the syngas composition and yield. The influence of temperature on the gasification process has been investigated over a wide range from 1000 to 1400 degrees C. Hydrogen yield increases with temperature via steam reforming of CH4 and C2H2 and with water gas shift reaction. A thermodynamic equilibrium calculation was conducted. It shows that equilibrium is reached within several seconds at the temperature of 1400 degrees C. After that, experiments of gasification were realized at 1400 degrees C with pure ethanol and with ethanol added bio-oil and in order to study the impact of dilution on the syngas yield. The influence of ash on the gasification process has also been evaluated. The ash seems to cause a decrease in the total amount of gas produced.

The liquid fuels production from biomass is one of the most efficient ways to energetic conversion, beyond the energy concentration, there are still economic and operational advantages due to transport and storage conditions. So, fast pyrolysis is the purpose of several researches all over the world for the production of bio-oils that can enrich the energetic supply. However, bio-oil has heterogeneous properties due to the biomass characteristics and to the operational conditions of the pyrolysis process. The present review aims to evaluate the state of art of the bio-oil production, their properties and their principal energetic ways of utilization. (Resume d'auteur)