The wood energy market remains nascent in the UK, despite climate change policies and energy security concerns. Transaction costs have been identified as one barrier to woodfuel development. However, few studies provide explicit insights into such barriers to spontaneous exchange in this sector and how they influence its formation. The study approaches the development of woodfuel in the South West Region of England through Transaction Costs Economics (TCE) and aims to identify the appropriate governance structure of the supply chain as a response to existing transactions costs. When transaction costs increase, seamless market exchange gradually gives way to credible contracting and even to full vertical integration or unified ownership. The TCE approach provides insights to analyse friction and barriers to exchange and allows for a dialogue between economics, law and day-to-day business decision-making. Fuel procurement from woodfuel suppliers to woodfuel users is central to this project in looking at the barriers to exchange. Original data was collected through 42 in-depth interviews, mainly with suppliers themselves but also from Forestry Commission, regional agencies, NGOs and lobbies involved. The results suggest the influence of transaction costs. Also, there is some evidence that wood-energy regional actors are embracing organisational diversity from known rural business structures to less familiar ones in the UK, such as cooperatives and new partnerships as answers to, among other factors, transaction costs. The evidence suggests that not only support to demand and supply is necessary, as generally identified, but it is also needed at its interface by supporting the governance of the supply chain. Some practical implications for both public and private sectors are identified to better articulate the response to this need.

Philosophiae Doctor - PhD / South Africa was considered to have attained universal access to modern energy, this meant that the number of households that have access to energy had successfully increased from 30% in 1994 to 87% in 2012. However, the situation in Nigeria is such that electricity generating figures are very poor and they cannot meet half of the demand of Nigerian households, and the majority of the states have challenges in accessing sufficient fossil fuels. However, recent trends in domestic energy consumption for both countries are becoming biased in favor of fuel-wood energy especially among low-income households, “descending the energy ladder”.

O uso de energias renováveis é uma tendência mundial, cada vez mais difundida, principalmente por razões ambientais e econômicas. Das diversas formas existentes de energias renováveis, a biomassa tem grande destaque, devido sua alta capacidade produtiva e versatilidade de aplicação. No Brasil, a biomassa tem grande expressão no suprimento energético do país, 31,6% do total, e a madeira corresponde à quase metade desse valor (BRASIL, 2008). Boa parte do suprimento dessa fonte provém ainda de florestas nativas, o que evidencia a necessidade de ampliação de plantios florestais visando o atendimento sustentado dessa crescente demanda. Entretanto, para que os plantios florestais cumpram efetivamente suas funções, os mesmos precisam ser orientados tanto por altas produtividades florestais como pelas qualidades ideais da madeira para uso energético. As espécies brasileiras são, relativamente, pouco conhecidas do ponto de vista energético, uma vez que a maior parte dos plantios são, tradicionalmente, realizados com espécies dos gêneros Pinus e Eucalyptus. O presente trabalho buscou trazer informações sobre características qualitativas e quantitativas de espécies florestais brasileiras, assim como a influência da idade nas características da madeira relacionadas ao uso energético, a fim de prover subsídios para a seleção de espécies com vocação para tal finalidade. A pesquisa foi desenvolvida a partir de plantios estabelecidos como parte de ações de recuperação de áreas florestais na região de Assis, SP. Em tais áreas, o Instituto Florestal do Estado de São Paulo desenvolveu equações alométricas para quantificação da produção de biomassa e carbono (MELO et al., 2008). A partir desses plantios foi realizado, adicionalmente, o presente estudo, que visou avaliar o potencial energético de espécies florestais nativas. No primeiro estudo, foram avaliadas 12 espécies entre 6 a 8 anos, para as quais foram estudas suas características quanto a produção de biomassa e as relacionadas as principais propriedades da madeira visando a finalidade energética. A segunda avaliação comparou as características da madeira de duas espécies em duas faixas de idade distintas, 6 e 8 anos e 36 e 37 anos. Com base nos resultados obtidos concluiu-se que: a) Nenhuma das espécies estudadas apresentou características limitantes em suas madeiras, em relação ao uso energético; b) O fator decisivo para a seleção de espécies para plantio foi a produção de biomassa; c) Em que pese esse último aspecto, quatro espécies se mostraram mais potenciais para o uso energético, quais sejam: Enteroplobium contortisiliquum (Tamboril), Anadenanthera macrocarpa (Angico-Vermelho), Cytharexyllum myrianthum (Pau-Viola), Acacia polyphyla (Monjoleiro); d) No estudo sobre a Anadenanthera falcata (Angico-Branco) e o Myracrodruon urundeuva (Aroeira), constatou-se a influência da idade em todas as características analisadas, para ambas as espécies analisadas. e) Ainda no segundo trabalho, constatou-se que a densidade básica, o poder calorífico, o carbono fixo, o teor de extrativos totais e o teor de lignina se relacionaram positivamente com o aumento da idade, enquanto que o teor de materiais voláteis e de cinzas mostraram influência negativa do efeito da idade. / The use of renewable sources of energy is a worldwide trend and is being increasingly widespread, mainly for environmental and economic reasons. Biomass has become one of the most commonly used renewable sources of energy in the last years. Many of the biomass fuels used today comes in the form of wood products and others sources. In Brazil, woody biomass has great expression in the country\'s energy supply, 12,5% of the total (BRASIL, 2008). However, the growing demand for such application requires the expansion of forest plantations for sustained production. Meanwhile, the forest plantations should be targeted by productivity of forests and the characteristics of wood during energy use to reach high yields. The Brazilian species are, relatively, little known in terms of energy uses, since most of the plantations are traditionally carried out with species of the genus Pine and Eucalyptus. This study aimed to bring about qualitative and quantitative characteristics of Brazilian forest species, as well as a study about the influence of age on the characteristics of wood energy uses, in order, to provide subsidies for the selection of species with vocation for this purpose. The research was conducted from recovery plantations in the region of Assis, Brazil. In such areas, the Forest Institute of the State of Sao Paulo developed tissues for quantification of biomass production and carbon (MELO et al., 2008) and, in addition, this study was conducted, aiming to offer new data and information for this important segment. In the first study, 12 species from 6 to 8 years were evaluated, on the energy production and properties of wood related to this purpose. The second assessment compared the characteristics of two species of wood in two distinct age groups, 6 and 8 years and 36 and 37 years. Based on the results it was concluded that: a) None of the species studied showed limitations on its woods characteristics, related to energy use; b) The decisive factor on the selection of species for planting was the production of biomass; c) Related with the last point, four species present more potential for energy use, namely: Enteroplobium contortisiliquum, Anadenanthera macrocarpa, Cytharexyllum myrianthum and Acacia polyphyla d) In the second study, conducted on the Anadenanthera falcata and Myracrodruon urundeuva, there was the influence of age in all properties of the woods, for both species analyzed. e) Considering the last species mentioned, it was found that the density, the heating value, the carbon fixed, the extractives content and the lignin content were positively associated with age, while the volatile materials content and ash showed negative influence of the effect of age.

The Commonwealth of Kentucky is taking steps to expand bioenergy production in response to federal policy initiatives as well as environmental and energy security concerns. The success of this industry will be impacted by the supply of feedstock available from private individuals who own a majority (78%) of forest resources in the state. Despite a developing body of bioenergy research, little is known concerning the social availability of forest biomass for energy production. This study measures intent to harvest energy wood among family forest owners using a mail-­‐based survey and tests the effect of educational materials provided to participants. The theory of planned behavior is used to model factors that affect landowner intentions. Two-­‐thirds of respondents reported that they intend to include energy wood in future harvests, but the educational material treatment did not affect intentions. Respondents’ attitudes, perceived subjective norms, and perceived control each had a significant effect on intent to harvest. Respondents also identified barriers that may prevent them from harvesting, providing forestry professionals with a list of challenges to overcome if supply is to be maximized. The results of this study are valuable for all stakeholders involved in the development of a sustainable biomass and bioenergy industry.

Thesis (M.Soc.Sc.) - University of KwaZulu-Natal, Pietermarizburg, 2009. / Full text also available online. Scroll down for electronic link.

O uso de energias renováveis é uma tendência mundial, cada vez mais difundida, principalmente por razões ambientais e econômicas. Das diversas formas existentes de energias renováveis, a biomassa tem grande destaque, devido sua alta capacidade produtiva e versatilidade de aplicação. No Brasil, a biomassa tem grande expressão no suprimento energético do país, 31,6% do total, e a madeira corresponde à quase metade desse valor (BRASIL, 2008). Boa parte do suprimento dessa fonte provém ainda de florestas nativas, o que evidencia a necessidade de ampliação de plantios florestais visando o atendimento sustentado dessa crescente demanda. Entretanto, para que os plantios florestais cumpram efetivamente suas funções, os mesmos precisam ser orientados tanto por altas produtividades florestais como pelas qualidades ideais da madeira para uso energético. As espécies brasileiras são, relativamente, pouco conhecidas do ponto de vista energético, uma vez que a maior parte dos plantios são, tradicionalmente, realizados com espécies dos gêneros Pinus e Eucalyptus. O presente trabalho buscou trazer informações sobre características qualitativas e quantitativas de espécies florestais brasileiras, assim como a influência da idade nas características da madeira relacionadas ao uso energético, a fim de prover subsídios para a seleção de espécies com vocação para tal finalidade. A pesquisa foi desenvolvida a partir de plantios estabelecidos como parte de ações de recuperação de áreas florestais na região de Assis, SP. Em tais áreas, o Instituto Florestal do Estado de São Paulo desenvolveu equações alométricas para quantificação da produção de biomassa e carbono (MELO et al., 2008). A partir desses plantios foi realizado, adicionalmente, o presente estudo, que visou avaliar o potencial energético de espécies florestais nativas. No primeiro estudo, foram avaliadas 12 espécies entre 6 a 8 anos, para as quais foram estudas suas características quanto a produção de biomassa e as relacionadas as principais propriedades da madeira visando a finalidade energética. A segunda avaliação comparou as características da madeira de duas espécies em duas faixas de idade distintas, 6 e 8 anos e 36 e 37 anos. Com base nos resultados obtidos concluiu-se que: a) Nenhuma das espécies estudadas apresentou características limitantes em suas madeiras, em relação ao uso energético; b) O fator decisivo para a seleção de espécies para plantio foi a produção de biomassa; c) Em que pese esse último aspecto, quatro espécies se mostraram mais potenciais para o uso energético, quais sejam: Enteroplobium contortisiliquum (Tamboril), Anadenanthera macrocarpa (Angico-Vermelho), Cytharexyllum myrianthum (Pau-Viola), Acacia polyphyla (Monjoleiro); d) No estudo sobre a Anadenanthera falcata (Angico-Branco) e o Myracrodruon urundeuva (Aroeira), constatou-se a influência da idade em todas as características analisadas, para ambas as espécies analisadas. e) Ainda no segundo trabalho, constatou-se que a densidade básica, o poder calorífico, o carbono fixo, o teor de extrativos totais e o teor de lignina se relacionaram positivamente com o aumento da idade, enquanto que o teor de materiais voláteis e de cinzas mostraram influência negativa do efeito da idade. / The use of renewable sources of energy is a worldwide trend and is being increasingly widespread, mainly for environmental and economic reasons. Biomass has become one of the most commonly used renewable sources of energy in the last years. Many of the biomass fuels used today comes in the form of wood products and others sources. In Brazil, woody biomass has great expression in the country\'s energy supply, 12,5% of the total (BRASIL, 2008). However, the growing demand for such application requires the expansion of forest plantations for sustained production. Meanwhile, the forest plantations should be targeted by productivity of forests and the characteristics of wood during energy use to reach high yields. The Brazilian species are, relatively, little known in terms of energy uses, since most of the plantations are traditionally carried out with species of the genus Pine and Eucalyptus. This study aimed to bring about qualitative and quantitative characteristics of Brazilian forest species, as well as a study about the influence of age on the characteristics of wood energy uses, in order, to provide subsidies for the selection of species with vocation for this purpose. The research was conducted from recovery plantations in the region of Assis, Brazil. In such areas, the Forest Institute of the State of Sao Paulo developed tissues for quantification of biomass production and carbon (MELO et al., 2008) and, in addition, this study was conducted, aiming to offer new data and information for this important segment. In the first study, 12 species from 6 to 8 years were evaluated, on the energy production and properties of wood related to this purpose. The second assessment compared the characteristics of two species of wood in two distinct age groups, 6 and 8 years and 36 and 37 years. Based on the results it was concluded that: a) None of the species studied showed limitations on its woods characteristics, related to energy use; b) The decisive factor on the selection of species for planting was the production of biomass; c) Related with the last point, four species present more potential for energy use, namely: Enteroplobium contortisiliquum, Anadenanthera macrocarpa, Cytharexyllum myrianthum and Acacia polyphyla d) In the second study, conducted on the Anadenanthera falcata and Myracrodruon urundeuva, there was the influence of age in all properties of the woods, for both species analyzed. e) Considering the last species mentioned, it was found that the density, the heating value, the carbon fixed, the extractives content and the lignin content were positively associated with age, while the volatile materials content and ash showed negative influence of the effect of age.

Dans le cadre du projet ANR AGATCO (Advance GAz Turbine for COgeneration) qui a débuté fin 2012, la conception d’un micro-cogénérateur aux granulés de bois permettant de produire 1,5 kW électrique et 10 kW thermique a été entrepris et est présentée dans ce manuscrit. Basé sur la technologie d’une turbine à air chaud à combustion externe, ce micro-cogénérateur utilise la combustion des granulés couplés à un échangeur de chaleur et une micro-turbine. La technologie demande la conception d’un nouveau foyer (brûleur et chambre de combustion) adapté pour la production de fumées à haute température (1200°C). Le défi est grand car le débit de fumées souhaité est important (27g/s) et la puissance de combustible est faible (15kW). Deux solutions sont proposées pour répondre à la problématique, la première utilise de l’air frais à température ambiante et la deuxième utilise le recyclage des fumées chaudes. La haute température des fumées permet d’obtenir une température d’entrée turbine de 1100°C après le transfert de chaleur dans l’échangeur. La caractérisation expérimentale et par simulation numérique de l’échangeur permet de vérifier ses performances. La micro-turbine utilise une technologie nouvelle de canaux hélicoïdaux à la place d’aubes qui lui permettent d’avoir des dimensions faibles pour les performances souhaitées. Les travaux effectués ont permis de mettre en valeur plusieurs résultats : la réalisation de la combustion haute température dans des conditions fortement défavorables, les performances très intéressantes de l’échangeur de chaleur tous en proposant des améliorations pour optimiser les échanges et les améliorations à apporter à la turbine / As part of the AGATCO ANR project (Turbine Advance GAz for cogeneration), which began at the end of 2012, the design of a micro-cogeneration generating 1.5 kW of electricity and 10 kW of heat was started and presented in this manuscript. Based on the technology of an externally fired gas turbine, this micro-CHP uses the combustion of pellets coupled to a heat exchanger and a micro-turbine. This technology requires the design of a new fireplace (burner and combustion chamber) suitable to produce fumes at high temperatures (1200°C). The challenge is significant because the desired smoke flow is important (27 g/s) and the fuel power is low (15 kW). Two solutions are proposed to solve the problem, the first uses fresh air at ambient temperature and the second uses recycled hot fumes. The high temperature of the fumes makes it possible to obtain a turbine inlet temperature of 1100°C after the transfer of heat into the exchanger. Experimental and numerical simulation characterization of the exchanger makes it possible to verify its performances. The micro-turbine uses a new technology using channel instead of blades allowing it to have small dimensions for the desired performance. The work carried out made it possible to highlight several results: the realization of the high temperature combustion in very unfavorable conditions, the very interesting performances of the heat exchanger while proposing improvements to optimize the exchanges and the improvements to be brought to the turbine

Ces dernières années, nous assistons à une prise de conscience généralisée de l'importance des impacts de notre mode de vie sur l'environnement, particulièrement en ce qui concerne le réchauffement global. L'objectif des politiques environnementales actuelles est le passage à des productions et des consommations durables qui passent par l'amélioration des performances énergétiques et environnementales des processus de production. De manière à réaliser cet objectif, la méthode de l'analyse du cycle de vie constitue à l'heure actuelle la méthode d'évaluation environnementale la plus largement utilisée. Cette méthode est ici appliquée dans le cadre de la production d'énergie renouvelable (électricité, chaleur, énergie motrice d'un véhicule) à partir de la biomasse d'origine agricole et forestière. Trois filières sont envisagées: la biométhanisation par fermentation d'effluents d'élevage et de cultures énergétiques, le bois énergie, et les biocarburants liquides purs et en mélange (5 % en volume) avec des carburants classiques (huile de colza, ester méthylique d'huile de colza, éthanol, éthyl tertio butyl éther). Il est prouvé que les énergies renouvelables participent à la réduction des impacts sur le réchauffement global et sur la diminution des ressources fossiles. Le présent travail apporte des éléments originaux sur plusieurs points. Outre ces deux aspects et au travers de trois méthodes d'analyse (CML 2 BASELINE 2000, ECOINDICATEUR 99 et IMPACT 2002+), d'autres catégories d'impact sont analysées de manière à fournir une information la plus complète possible sur la charge environnementale des filières étudiées. Les productions d'énergie des différentes filières considérées sont comparées avec des filières classiques utilisant des ressources fossiles pour un ensemble de charges environnementales en concordance avec la méthodologie de l'analyse du cycle de vie. Les méthodes d'analyse d'impact évoquées ci-dessus sont introduites successivement pour les comparaisons de chacune des filières avec les filières classiques. Afin de vérifier si le résultat environnemental obtenu est robuste à la méthode d'analyse d'impact, les trois filières utilisant la biomasse sont comparées entre elles avec les trois méthodes d'analyse d'impact. Compte tenu des résultats d'analyse d'impact, nous analysons si l'incertitude globale sur le résultat permet de considérer que les productions énergétiques comparées sont significativement différentes d'un point de vue environnemental. Les résultats montrent de manière générale, que les filières biométhanisation, bois énergie et biocarburants sont plus intéressantes que les filières classiques d'un point de vue environnemental global. L'application des trois méthodes d'analyse d'impact a permis de montrer que le choix d'une méthode n'est pas anodin et que les résultats peuvent être sensiblement différents en utilisant l'une ou l'autre des méthodes. La comparaison entre elles des trois filières montre que, pour des valorisations énergétiques analogues (production de chaleur en chaudière par exemple), la production énergétique par la filière biométhanisation est plus intéressante que la valorisation de l'huile (scores environnementaux de la production de chaleur en chaudière par la méthode IMPACT 2002+: 4,15.10-6 pt pour la chaudière au biogaz et 8,55.10-6 pt pour la chaudière fonctionnant à l'huile de colza). Le niveau de classement de la production énergétique de bois va dépendre des hypothèses retenues sur la gestion des cendres et sur le contrôle ou non des émissions. Les résultats d'analyses d'incertitude réalisées systématiquement montrent que l'incertitude globale est dans certains cas importante et ne permet pas de différencier de manière significative les systèmes de produits. Les différentes informations présentées dans cette étude constituent cependant autant d'éléments d'analyse objectifs dans le cadre d'un processus de décision qui concernerait le développement futur des filières étudiées./ Last few years, we attend a generalized awakening of our way of life influence to environmental impacts, particularly with regard to the global warming. The goal of the current environmental policies is the conversion to sustainable consumption and productions, making necessary the improvement of energy and environmental performance. To carry out this goal, the life cycle assessment is at present, the most largely used environmental assessment method. This method is applied in this study within the framework of the renewable energy (electricity, heat, mechanical energy in a vehicule) production from agricultural and wood biomass. Three reactor systems are considered: The co-fermentation of breeding effluents and energy crops, the wood fuels, the neat and blended (5 % volume) biofuels with fossil fuels. The biofuels considered are: rapeseed oil, rapeseed oil methyl ester, ethanol from wheat and sugar beet and ETBE (ethyl tertio butyl ether). It is proven that renewable energies take part in the global warming mitigation and in the reduction of the fossil resources depletion. The present work brings original elements on several points. In addition to these two impact categories and through three assessment methods (CML 2 BASELINE 2000, ECOINDICATOR 99 and IMPACT 2002+) we approach other impact categories in order to provide the most complete information on the environmental load of the studied reactor systems. The energy productions of the various reactor systems considered are compared with conventional reactor systems using fossil fuels for a whole of environmental loads, in agreement with the life cycle assessment methodology. The impact assessment methods cited above are introduced successively for each reactor system comparison with the traditional ones. In order to check if the environmental result obtained is robust with the impact assessment method, the three reactor systems using biomass are compared between each other with the three impact assessment methods and the results are analyzed. Taking into account the impact assessment results, we analyze if the global uncertainty on the result makes it possible to consider that the compared energy productions are significantly different from an environmental point of view. The impact assessment results show in a general way, that the reactor systems considered are more interesting from a global environmental point of view than the traditional ones. The application of the three impact assessment methods shows that it does matter which method one choose and that the results can be sensitive to the method used. The three reactor systems comparison shows that for similar energy development (heat production in a boiler for example), the energy production by using biogas from fermentation is more interesting than the energy production from rapeseed oil (IMPACT 2002+ scores for boiler heat production: 4,15.10-6 pt for the biogas boiler and 8,55.10-6 pt for the rapeseed oil boiler). The classification of wood energy production will depend on the assumptions retained on ashes management and on the emissions control. The results of uncertainty analysis carried out systematically show that the global uncertainty is in some cases important and does not allow to differentiate significantly the compared product systems. The various information highlighted in this study however constitutes as many objective elements of analysis within the framework of a decision-making process which would relate to the future development of the studied reactor systems.

La problématique des émissions de particules fines, posant des risques sanitaires et environnementaux avérés, a été très médiatisée ces dernières années. La solution mise en place consiste à aider financièrement les particuliers pour renouveler le parc d’appareils. Or, une utilisation non optimisée d’un appareil dégrade de manière significative ses émissions. Afin d’amender entre autres cette réflexion, de nombreuses campagnes expérimentales ont été menées au travers de caractérisations physico-chimiques complètes et innovantes des fumées, en particulier des particules fines : la Microscopie Electronique à Balayage, la microanalyse X et la détermination du type de carbone constitutif (Carbone Elémentaire, Carbone Organique). En premier lieu, la définition des paramètres d’utilisation de l’appareil et leurs niveaux de réponse ont permis de proposer une réduction significative des émissions dont celles de particules fines. Ainsi, les impacts des paramètres comme la nature du combustible, le mode d’allumage et l’injection d’air secondaire ont été quantifiés. Ensuite, les mécanismes de formations des particules ont été définis. Dans un second temps, ce travail de thèse s’est intéressé à l’évolution des caractéristiques des particules entre la chambre de combustion de l’appareil et le champ proche, permettant d’aller au-delà de l’étude normative classique. De nouveaux savoirs sur les particules ont ainsi été mis en évidence. L’ensemble de ces nouvelles connaissances, aidant à mieux connaître les particules produites par la combustion de bois dans des appareils indépendants, permettront dans le futur de créer des systèmes de traitement spécifiques et efficaces / The issue of the emissions of fine particles, known for their health and environmental hazards, has been significantly covered in recent years. The governments made the decision to help mainly financially the private individuals in order to renew the domestic appliances stock. However, a non-optimized use of an energy-efficient appliance can degrade system performances. In order to solve this issue, many experimental campaigns have been achieved through complete and innovative physicochemical characterizations of the smoke, especially of the fine particles : Scanning Electron Microscope, X-ray microanalysis and assessment of the constitutive Carbon (Elemental Carbon, Organic Carbon). First of all, the definition of the use parameters for the appliance and their impacts allowed offering a significant reduction of the fine particles emissions. In this work, the influences of the parameters such as the nature of the fuel, the ignition mode and the air secondary injection were in this way quantified. In order to better understand the origin of these emissions produced regardless of the combustion quality, the mechanisms of formation of all kinds of particles were defined. In a second phase, this work paid attention to the evolution of the characteristics of particles from the combustion room to the near-field. This enabled to go over the classic normative study. New knowledge on particles was brought to light, helping to better know the particles generation from domestic wood appliances. This could allow in the future to create some specific and efficient treatment systems

Les voies sèches de valorisation du bois énergie sont de plus en plus exigeantes vis-à-vis de la qualité de la matière première et notamment quant à sa teneur en eau. Ainsi, une étape intermédiaire de préconditionnement, sur site industriel, tend à se développer. La mise en œuvre de séchoirs en continu est alors séduisante de par son faible coût et sa parfaite intégration dans la ligne de production. Cependant, elle n'est pas sans écueil : la variabilité de la biomasse et l'hétérogénéité des conditions climatiques au sein du séchoir rendent fastidieux le dimensionnement du séchoir et de la source de chaleur associée d'une part et la maximisation du flux matière d'autre part.Notre étude a pour ambition de développer un outil informatique d'aide à la conception et à l'optimisation de séchoirs en continu traversés par un lit condensé de particules de bois. Pour y parvenir, nous associons une approche expérimentale et une approche numérique du procédé. La démarche scientifique s'articule autour de deux échelles représentatives :- A l'échelle de la particule de bois, le modèle de Van Meel, reposant sur le concept de courbe caractéristique de séchage, est étendu : le couplage entre transferts de chaleur et de masse est rendu explicite. Nous disposons dès lors d'un modèle réactif et prédictif en conditions climatiques variables. Parallèlement, un premier dispositif expérimental original est conçu et construit pour l'étude du séchage de particules de bois isolées. Les données recueillies sont alors analysées en vue d'alimenter en paramètres et de valider le modèle semi-analytique ;- A l'échelle du séchoir, une modélisation double-échelle est adoptée pour tenir compte de l'évolution des conditions climatiques. Un soin particulier est apporté à la modélisation, se voulant être la plus proche possible des installations existantes : à ce titre, les transferts au niveau de la paroi du séchoir sont pris en compte, ainsi que la variabilité des particules de bois. Parallèlement, un second dispositif expérimental original est conçu et construit pour l'étude du séchage de particules disposées en lit. Les données recueillies sont alors confrontées aux simulations du modèle double-échelle.La validation du modèle s'étant révélée probante tant à l'échelle de la particule qu'à celle du séchoir, une utilisation du code pour l'aide à la conception et à l'optimisation d'installations industrielles a pu être envisagée. Ainsi, ce travail s'achève-t-il par deux études de cas à travers lesquelles nous explorons le potentiel du modèle pour maximiser le flux matière tout en garantissant la qualité du produit et l'efficacité énergétique du séchoir. / The dry conversion routes of wood to energy require more and more improvement in the quality of raw material, particularly regarding to its moisture content. That is why a preliminary step of preconditioning tends to be developed on the industrial sites. The use of continuous dryers is then tempting because of their low cost and their perfect integration in the production line. However it is not without pitfall: the climatic conditions heterogeneity inside the dryer, on the one hand, and the biomass variability, on the other hand, make the utilization of these industrial plants tedious.Our study aims to develop a computing tool to help engineers optimizing and to designing continuous dryers passed through by a condensed bed of wood particles. For this result, an experimental approach of the process is associated to a numerical one. The scientific method revolves around two representative scales:• At the wood particle scale, the Van Meel model, based on the concept of characteristic drying curve, is enhanced: the coupling between heat and mass transfer is made explicit. So we obtain a reactive model which is predictive when the climatic conditions are variable. Meanwhile, a first original experimental device is designed and built in order to study the drying of single wood particles. Thanks to the collected data, the semi-analytical model is provided with parameters and is validated;• At the dryer scale, a dual-scale approach is chosen in order to take into account the evolution of the climatic conditions. A particular attention is paid to the modeling in order to make it as similar as possible to the existing installations: as such, the transfers at the wall surface and the variability of wood particles are included. Meanwhile, a second original experimental device is designed and built in order to study the drying of a wood particles stack. The data collected are then confronted with simulations of the double-scale model.The validation of the model has proven to be convincing at the particle scale and at the dryer one. Therefore a utilization of the code to help in the design and optimization of industrial plants can be considered. Thus, the work ends by two case studies through which we explore the potential of the model to maximize material flow while ensuring product quality and efficiency of the dryer.