Potential of Forest Wood Biomass in Bulgaria, Market and Possibilities for Its Utilization

The total annual increment in forests in Bulgaria is about 14.5 Mio m^3 of the growing stock, of which the harvesting amounts at 5-6 Mio m^3 of fallen wood. An increase of the actually harvested quantities of wood is possible and it may rise up to 8-10 Mio m^3. The volume of forestry waste is 1,066,900 m^3, incl. economically accessible forestry waste are 373,400 m^3. Every year, there are about 3.0 Mio m^3 of wood which are obtained by the wood category, being 2.5 Mio m^3 of that same one used by the population as fire wood for stoves about 40% efficiency. In that connection, a map has been elaborated of the economically accessible forest-wood waste from the wood harvesting. Taking into account the data on the share of that wood, is considered capable for energy production, as well as the fact that a part of fire wood shall not be used in the conventional way but shall be processed, instead, that is to say, transformed into chips, pellets and briquettes, a map of category of woods has been made for the purposes and needs of this elaboration. There are some reserves as regards to thinning operations where small- and medium-sized wood is harvested and from temporarily inaccessible forest exploitation basins or the so called ＂closed basins＂ should arrive to. This paper proposes the most promising technologies for waste processing and transformation into chips, which could be applicable in Bulgaria and in some other countries as well.

Utilization of Wood Biomass for Organic Soil Based on the Soil Fertility Index (SOFIX)

Possibility of wood biomass for preparing organic soil was examined to construct reproducible and stable organic standard soil. Seven organic soils were constructed from base soils and additive materials based on the recommended values of the soil fertility index (SOFIX) (total carbon ≥ 25,000 mg/kg, total nitrogen ≥ 1500 mg/kg, total phosphorus ≥ 1100, and total potassium of 2500 to 10,000 mg/kg). Base soils were prepared from two types of wood biomass (big- and small-sized wood chips) at 50%, 60%, and 70% (v/v) and other organic materials such as peat moss, black soil, and mountain soil. Additive materials (soybean meal, oil cake, cow manure, and bone meal) were amended into all organic soils at the same amount. Incubation experiment showed that bacterial biomass in all organic soil was greater than 6 × 108 cells/g-soil after addition of 30% of water content for 1 week. In addition, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) analysis resulted in a stable bacterial diversity of the organic soil prepared from the small size wood chip at 70%. Chemical properties of all organic soils were within the recommended values of SOFIX. The plant cultivation experiment showed that fresh Brassica rapa var. peruviridis weights in the organic soils with 50%, 60%, and 70% of small-sized wood chip were 5%, 16%, and 27% higher than that of the chemical fertilizer-amended soil. The organic soil with 70% of small wood chip was the best in the seven organic soils in this study.

Impact of exclosures on wood biomass production and fuelwood supply in northern Ethiopia

In the Ethiopian highlands, communal grazing lands are one of the major land uses, and are source of livelihood for the rural people. Free and uncontrolled grazing in the communal grazing lands is the dominant grazing system. The traditional uncontrolled and free grazing system has caused severe degradation of the grazing lands. As a result, communities have started to establish exclosures and support the restoration of degraded communal grazing lands. Studies have shown that exclosures are effective to restoring degraded communal grazing lands and improving ecosystem services. However, studies that investigate the changes in aboveground biomass following the establishment of exclosures and compare it with fuelwood demand of the beneficiaries in our study area is lacking. Therefore, our study aimed at:(1) quantifying yearly biomass accumulation in exclosures and compare it to fuelwood demand of households that manage the exclosures;(2) assessing household energy sources and their consumption levels. To monitor changes in biomass production with over time, replicated(n = 3) 5 and10 year-old exclosures were sampled. To investigate fuelwood sources and consumption patterns, household surveys, key informant interviews and focus group discussion were conducted. Our results demonstrated that total biomass production increased with exclosure age. In both exclosure, biomass production from Vachellia etbaica was significantly(p \ 0.05) greater than that from Euclea.racemosa. Average daily fuelwood consumption per person was(0.63 ± 0.2) kg day^(-1). This means that the total biomass(27.5 Mg year^(-1)) obtained from 114.6 ha of exclosures covers only 9.4% of yearly fuelwood demand of the residents who manage the sampled exclosures. Nearly all respondents(95%) confirmed that they travel more than10 km day^(-1) to gather fuelwood from surrounding degraded forest patches. We recommend plantings of fast growing native tree species within exclosures and around homesteads to provide a sustainable fuelwood supply and using improved stoves to address the problem of fuelwood shortage. District agricultural offices could provide seedlings of native plant species, while communities provide unpaid labour for planting and managing plantations.

Forest aboveground biomass estimates in a tropical rainforest in Madagascar: new insights from the use of wood specific gravity data

To generate carbon credits under the Reducing Emissions from Deforestation and forest Degradation program（REDD＋）, accurate estimates of forest carbon stocks are needed. Carbon accounting efforts have focused on carbon stocks in aboveground biomass（AGB）.Although wood specific gravity（WSG） is known to be an important variable in AGB estimates, there is currently a lack of data on WSG for Malagasy tree species. This study aimed to determine whether estimates of carbon stocks calculated from literature-based WSG values differed from those based on WSG values measured on wood core samples. Carbon stocks in forest biomass were assessed using two WSG data sets：（i） values measured from 303 wood core samples extracted in the study area,（ii） values derived from international databases. Results suggested that there is difference between the field and literaturebased WSG at the 0.05 level. The latter data set was on average 16 % higher than the former. However, carbon stocks calculated from the two data sets did not differ significantly at the 0.05 level. Such findings could be attributed to the form of the allometric equation used which gives more weight to tree diameter and tree height than to WSG. The choice of dataset should depend on the level of accuracy（Tier II or III） desired by REDD＋. As higher levels of accuracy are rewarded by higher prices, speciesspecific WSG data would be highly desirable.

Growth Characteristics, Biomass and Chlorophyll Fluorescence Variation of Garhwal Himalaya’s Fodder and Fuel Wood Tree Species at the Nursery Stage

Fodder and fuel wood deficiency in the Himalayan region is well recognized. Rural inhabitants are exploiting these forest resources for their livelihood for generations which leads to severe deforestation. The aim of this study was to identify the fast growing fodder and fuel wood tree species of Garhwal Himalayas at nursery stage with wider relevance and great potential for extensive afforestation programmes. Seed of Bauhinia purpurea L., Bauhinia retusa Roxb., Bauhinia variegate L., Celtis australis L., Ficus nemoralis Wall., Ficus roxburghii Wall., Grewia optiva Drummond, Leucaena leucocephala (Lam.) de Wit, Melia azedarach L., Ougeinia oojeinensis (Roxb.) Hochr., Quercus leucotrichophora A. Camus, Terminalia alata Heyne ex Roth. and Toona ciliate M. Roem. were collected from the superior trees and seedlings were raised. After one year and one month of establishment at the nursery, the growth characteristics, biomass and chlorophyll fluorescence (dark-adopted Fv/Fm) of each species were also recorded. G. optiva had shown the highest growth in terms of height, basal diameter increment and number of branches, while production of leaves was more on O. oojeinensis. Biomass and chlorophyll fluorescence (maximum quantum yield or photochemical efficiency of PSII) was found highest in Q. leucotrichophora which indicates photosynthetically this species was most active among the studied fodder and fuel wood tree species. The information in this communication could be utilized for developing various conservation and sustainable strategies in the Garhwal Himalayas to mitigate

Progress in the technology of energy conversion from woody biomass in Indonesia

Sustainable and renewable natural resources as biomass that contains carbon and hydrogen elements can be a potential raw materials for energy conversion. In Indonesia, they comprise variable-sized wood from forests （i.e. natural forests, plantations and community forests that commonly produce small-diameter logs used as firewood by local people）, woody residues from logging and wood industries, oil-palm shell waste from crude palm oil factories, coconut shell wastes from coconut plantations, traditional markets as well as skimmed coconut oil and straws from rice cultivation. Four kinds of energy-conversion technologies have been empirically tested in Indonesia. First, gasification of rubber wood from unproductive rubber trees to generate heat energy for the drying of fermented chocolate seeds. Secondly, energy conversion from organic vegetable waste by implementing thermophylic fermentation methods that produce biogas as a fuel and for generating electricity and also concurrently generate organic by-products called hygen compost. Thirdly, gasification of charcoal and wood sawdust for electricity generation. Finally, environment-friendly energy conversion by carbonizing small-diameter logs, sawdust, wood slabs and coconut shells into charcoal. This yielded charcoal integrated with wood vinegar production through condensation of smoke/vapors emitted during carbonization, thereby mitigating the impact of air pollution. Among the four experimental technologies that of integrated charcoal and wood vinegar production had been spectacularly developed and favored by rural communities. This technology brought added value to the process and product due to the wood vinegar, useful as bio-pesticide, plant-growth hormone and organic fertilizer. Such integrated and environment-friendly production, therefore, should be sustained, because Indonesia occupies a significant and worldwide position as charcoal-producing and marketing country. The technology of integrated wood vinegar-charcoal production hence deserves its dissemination throughout Indonesia, particularly to the charcoal industry that still produces charcoal without condensing the generated vapor/smoke, hence polluting the air.

木材用于水伏发电的研究进展

化石能源的过度使用带来能源枯竭与环境恶化问题,绿色可持续成为发展的首要目标。水能作为目前较为优质的清洁能源,其中一部分潜在的能量有待转化利用。近年来,水伏发电受到国内外学者的广泛关注,被认为是一种新兴的深度挖掘水能资源的手段,研究者们取得了一系列关于功能材料与水滴、水波、水蒸发与湿气等相互作用输出电能的研究成果。开发生物质基水伏发电材料有助于推动可再生能源的充分利用。木材是一种储量充足、可再生、易加工的材料,同时具有独特的多级孔道结构,内部富含极性基团,有良好的机械强度,因此木材在水伏发电领域具有一定应用前景。笔者总结了水伏发电技术的研究进展,阐述了水伏发电的理论基础,基于水伏效应的能量转换方式及其器件材料的选择,介绍了木材用作水伏发电器件材料的研究成果,归纳了研究者为提高水伏发电器件的输出功率,对木材进行表面修饰、孔道调控、材料负载、碳化处理的功能化改性方法,并对其面临的挑战与应用前景进行展望。

生物质基胶黏剂的研究进展

我国的木材胶黏剂消耗量巨大,以丰富的生物质资源制备生物质基胶黏剂作为传统三醛树脂胶黏剂的补充具有重要的现实意义。本文综述了生物质原料在三醛树脂中的应用及生物质基胶黏剂的研究进展,展望了生物质基胶黏剂的发展趋势及研究方向,为我国生物质基胶黏剂行业未来发展提供参考。

基于林木热解产物的燃料电池制备与性能研究

生物质热解可产生热解炭和热解油,其中热解炭存在丰富的表面官能团和孔隙结构,热解油中含有多种可以发生氧化还原的组分,其可分别用于制备燃料电池电极材料和燃料。文章优化了林木热解油作为碱性燃料电池燃料的工作条件,并以林木热解炭为原料,采用K2CO3活化和金属负载的方法制备了林木活性炭(AC)和3种林木热解炭复合电极(AC/Fe,AC/Mn,AC/Fe/Mn),通过傅里叶红外光谱、扫描电子显微镜和电化学工作站分析了电极材料的微观结构、表面性质和电化学活性。结果表明:在以AC为阴极电极时,较优的林木热解油质量分数和环境温度分别为30%和60℃,此时电流为3.10 mA;在优化条件下,AC/Fe,AC/Mn和AC/Fe/Mn的电流分别为8.02,12.57,15.25 mA,较AC分别提升159%,305%,392%;在优化条件下,以AC/Fe/Mn为阴极电极,加入12 mL林木热解油作为燃料时,基于林木热解产物的燃料电池可持续工作408.6 min,总放电量为40.61 mAh。

南方典型红壤侵蚀区马尾松林立木生物量无人机遥感估测

以南方典型红壤侵蚀区长汀县河田镇为例,结合无人机与激光雷达产生的点云数据优势,通过局部最大值和分水岭算法反演单木树高(H)和冠层半径(R_(c)),拟合以H和R_(c)为变量组合的异速生长方程,得到以新冠层参数为底的马尾松立木生物量模型。结果表明:提取树高的决定系数(R^(2))和均方根误差(RMSE)分别为0.93和0.49 m;计算冠层半径的R2和RMSE分别为0.88和0.64 m;估算立木生物量的R^(2)和RMSE分别为0.89和3.37 kg。本研究通过无人机遥感影像定量参数并构建的异速生长方程中,以组合(H+R_(c))为底的异速生长方程估测马尾松林立木生物量的精度较高,可以有效估测马尾松林立木生物量,可为南方典型红壤侵蚀区马尾松林立木生物量准确估测提供参考。

木醋液不同施用时期对油菜生长及产量的影响

为恰当使用木醋液增产,盆栽和大田种植甘蓝型油菜杂交品种华油杂9号,调查木醋液不同叶面喷施次数、不同施用间隔时间以及不同播期条件下,木醋液对油菜生长与产量的影响。盆栽结果表明,连续和间隔喷施2~4次的木醋液显著提高油菜的总干重29.63%~74.07%。同时连续与间隔喷施4次的木醋液可显著提高油菜的叶面积81.58%~85.65%。大田试验结果表明,苗期、蕾薹期、花期分别喷施1次、2次、3次处理的油菜,最终籽粒产量分别显著提高3.30%、9.52%、11.38%,蛋白含量分别降低2.62%、4.02%、4.68%。3个不同播期喷施木醋液处理的大田产量较对照分别显著提高20.13%、23.25%、13.97%,单株有效角果数分别提高47.29%、61.87%、72.90%。综合分析表明,在油菜生长期间喷施木醋液2~4次,每次间隔5 d以上的促进效果更好。不同播期条件下,木醋液对油菜生长与产量的影响以适期(即10月9日)播种效应更显著。

不同木屑对四川烟熏腊肉中挥发性物质的影响

为探究不同木屑(柏叶屑、柏木屑、松木屑、苹果木屑和混合木屑(柏叶屑和苹果木屑质量比1∶1))对四川烟熏腊肉风味的影响,采用闷燃发烟工艺制备腊肉,在生物质组分检测和感官评价的基础上,采用电子鼻和气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)技术结合主成分分析和相关性分析法对不同木屑熏制腊肉风味特征进行分析。结果表明:与其他干材相比,柏叶屑中蛋白质、油脂和木质素含量较高,熏制腊肉风味较好,烟熏风味强度较高,但腊肉色泽不具备明显优势;利用GC-MS在6组腊肉中共检出187种挥发性化合物,柏叶屑和混合木屑熏制腊肉中的萘及其衍生物、含氮化合物相对含量高于其他干材熏制腊肉,酚类化合物相对含量低于其他干材熏制腊肉;主成分分析结果表明,萘及其衍生物、含氮化合物的相对含量差异是区分柏叶屑熏制腊肉与干材熏制腊肉的主要依据;相关性分析结果显示,半纤维素对挥发性物质中酚类相对含量的作用大于木质素,萘及其衍生物相对含量与油脂、蛋白质、木质素含量均呈正相关,但相关性均不显著(P>0.05),因此木屑种类对腊肉中萘及其衍生物产生的影响可能大于木屑生物质组成对其的影响。本研究结果为四川再造林木在烟熏食品加工中的应用提供了参考依据。

酶解木质基分级多孔碳的制备及其电化学性能

【目的】利用酶解技术调控木质碳分级多孔结构,以制备具有优异电化学性能的碳材料,进而拓展多孔生物质碳材料的应用范围。【方法】采用亚氯酸钠和纤维素酶酶解椴木,经高温碳化制备分级多孔碳材料。通过表征分级多孔碳的微观形貌、比表面积、孔隙结构、石墨化程度、表面元素和官能团,揭示纤维素酶用量和酶解时间对其微观结构及电化学性能的影响。【结果】酶解后椴木内部呈现出丰富的微孔/介孔结构,形成了分级多孔结构。多孔碳的比表面积随纤维素酶用量和酶解时间的增加而增大,无序度提高。当纤维素酶用量200 mg、酶解时间48 h时,比表面积达到978.925 m^(2)/g,平均孔径达到2.285 nm;在0.1 A/g的电流密度下,质量比电容为300.8 F/g,等效串联电阻为0.47Ω。【结论】本研究制备的酶解木质基分级多孔碳具有出色的电化学性能、分级孔隙结构,因此具有广泛的应用前景。

生物质基木竹材改性剂研究进展及存在问题

随着环境和资源问题的加剧,木竹材改性的环保性和安全性得到了越来越广泛的关注。传统木竹材改性技术大多以化石资源为原料,普遍存在高能耗、高污染、改性材不可降解等问题。因此,需要探索高效、低能耗、绿色环保的木竹材改性技术。生物质基木竹材改性剂源于生物质资源,不仅能改善木材和竹材性能,还能降低原材料的化石资源依赖性,最大限度保持木质材料的可降解性能,这为木竹材改性的发展提供了新思路。本文以糠醇树脂改性、松香改性、聚酯类聚合物改性等改性方法为主,对近年来以生物质及其衍生物作为木竹材改性剂的相关研究进行了总结,并对其存在的问题进行了分析,以期为木竹材改性技术的研究与发展提供借鉴。

Vibrational Structure of Selected Compounds Derived from Biomass： Lignin Dimers, Selected Aldopentoses and Aldohexoses

The production of chemicals from biomass is a very challenging process due to its diverse chemical composition. Lignin, cellulose and hemicellulose are the three main biopolymers of wood biomass, with cell walls ＆plant origin. Lignin has been chosen for the present studies due to its range of different linkages and structures. The present work involved a computational study of the most dominant lignin dimers and their vibrational structures, based on the Density Functional Theory method. Full geometry optimization of the compartments used the StoBe code with cluster model and non-local functional （RPBE） approach. The calculations of the vibrational frequencies were performed with harmonic approximations as well as an anharmonicity fit in the Morse potential function, as implemented in the StoBe code. In the case oflignin, the calculations included three different precursors based on： coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. To represent the cellulose and hemicellulose derivatives, selected aldopentoses and aldohexoses （arabinose, xylose, glucose, galactose, and mannose） were considered. Presented here are the theoretical investigations for a variety of biomass derived compounds, to give the possibility of obtaining a theoretical VBD （Vibrations Basis Database） for experimental spectra interpretation. Such a database could be further used in the preliminary composition assessment of biomass derived substrates, which will be discussed here in more detail.

Potential Impact of Biomass Cogeneration Plants on Achieving Climate Neutrality of BIH until 2050

The paper analyzes the potential of Biomass Combined Heat and Power (BCHP) plants in Bosnia and Herzegovina (BiH) in achieving climate neutrality until 2050. Two scenarios for reducing GHG emissions from the power generation sector in BiH until 2050 were developed. Scenarios were developed using LEAP, a software tool for energy policy analysis and climate change mitigation assessment. The complete final energy consumption and existing primary energy mix in BiH were included. Both scenarios imply a significant reduction in electricity generation from coal-fired power plants (CFPP). The first scenario (S1) involves the construction of a substitute CFPP unlike the second scenario in which there is no construction of a new CFPP, but part of the reduction in electricity generation from the CFPPs is compensated by BCHPs. The second scenario (S2) achieves a significantly higher reduction in GHGs emissions and provides an answer to the question of how much wood biomass is needed for the operation of BCHP for enabling the decarbonization of the power generation sector by 2050. S1 also represents a step toward reducing GHG emissions. Emissions from power generation in 2030 are about 60% lower than in 2015, i.e. by closing part of the existing CFPPs fleet, while in 2050 GHG emissions will be reduced by 12.26 million tons of CO2eq compared to 2015. The main advantage of S2 is the gradual phase-out of CFPPs and construction of BCHPs, which means incomparably lower GHG emissions, negligible in 2050, representing a key argument for the deployment of biomass potential for power generation. The technical potential of unused wood biomass in BiH is 7.44 PJ annually or 620,620 t annually. These quantities would be sufficient for the levels of electricity production in Scenario 2 by 2035. After that, the existing available technical potential is not enough. This means that BiH needs to increase biomass production and its technical potential to enable the implementation of that scenario.

大花序桉和托里桉生长量及主要材性比较

于2014年在福建漳州龙海九龙岭国有林场,选取12年生大花序桉和托里桉人工林为研究对象,对其生长量、木材物理和力学性质进行研究。结果表明,大花序桉平均胸径、平均树高、平均单株材积、单位面积木材蓄积量分别是托里桉的1.4倍、1.39倍、2.56倍、1.43倍。大花序桉、托里桉木材的气干密度分别为0.77、0.58 g·cm^(-3),全干和气干时的干缩率分别为15.8%和9.9%、14.4%和9.7%,气干时和吸水后的湿胀性分别为7.2%和19.0%、5.5%和16.9%。大花序桉木材的顺纹抗压强度为67.8 MPa、抗弯强度为135.9 MPa,高于托里桉;同时大花序桉的端面、径面和弦面硬度均高于托里桉。综合结果表明,与托里桉相比,大花序桉具有较高的生产力,木材物理力学性质优良,木材综合强度属中上,是优良的实木用材。研究结果可为大花序桉和托里桉的科学经营及木材利用提供参考。

Implementation of a Forest Biomass-Based Biofuel Industry： A Canadian Experience

The forest biomass is an abundant renewable resource from which biofuels can be derived. In the Kraft process, the cellulose is extracted from the wood to form the paper pulp while the other organic components, primarily hemicelluloses and lignin, are burnt to produce steam. It is possible to divert part of the hemicelluloses or lignin to produce fuels on site, a mode of operation referred to as the integrated forest biorefinery. Hemicelluloses can be hydrolysed into sugars which in turn are converted into ethanol or butanol, while lignin can be extracted from a residual process stream, the black liquor, by acid precipitation, de-ionized, dried and directly used as a fuel or further processed into value added chemicals. Biorefinery processes have been proposed and analysed by simulation on Aspen Plus. Intensive integration of thermal energy, water and material systems is of paramount importance to the sustainability of the global site; the increased energy load on the utility systems could cause rising dependency of the global site on fossil fuels. To avoid this consequence, a new original energy efficiency analysis and enhancement methodology has been developed and validated on actual Canadian Kraft mills before being applied to the integrated biorefinery and, has produced remarkable results far superior to the current engineering practice. This has led to the concept of the GIFBR （green integrated forest biorefinery）, i.e., an industrial site with zero fossil fuel consumption and reduced GHG （greenhouse gases） emissions vs. the Kraft process and biorefinery plant alone. The GIFBR incorporates a woody biomass gasifier producing syngas as a fuel for the integrated biorefinery and for steam production or sale. It can also include a CHP （combined heat and power） unit driven by steam made available by liberated production capacity from the installed power plant.

Re-estimating the changes and ranges of forest biomass carbon in China during the past 40 years

Background: In recent decades the future of global forests has been a matter of increasing concern, particularly in relation to the threat of forest ecosystem responses under potential climate change. To the future predictions of these responses, the current forest biomass carbon storage(FCS) should first be clarified as much as possible,especially at national scales. However, few studies have introduced how to verify an FCS estimate by delimiting the reasonable ranges. This paper addresses an estimation of national FCS and its verification using two-step process to narrow the uncertainty. Our study focuses on a methodology for reducing the uncertainty resulted by converting from growing stock volume to above-and below-ground biomass(AB biomass), so as to eliminate the significant bias in national scale estimations.Methods: We recommend splitting the estimation into two parts, one part for stem and the other part for AB biomass to preclude possible significant bias. Our method estimates the stem biomass from volume and wood density(WD), and converts the AB biomass from stem biomass by using allometric relationships.Results: Based on the presented two-step process, the estimation of China’s FCS is performed as an example to explicate how to infer the ranges of national FCS. The experimental results demonstrate a national FCS estimation within the reasonable ranges(relative errors: + 4.46% and-4.44%), e.g., 5.6–6.1 PgC for China’s forest ecosystem at the beginning of the 2010 s. These ranges are less than 0.52 PgC for confirming each FCS estimate of different periods during the last 40 years. In addition, our results suggest the upper-limits by specifying a highly impractical value of WD(0.7 t·m-3) on the national scale. As a control reference, this value decides what estimate is impossible to achieve for the FCS estimates.Conclusions: Presented methodological analysis highlights the possibility to determine a range that the true value could be located in. The two-step process will help to verify national FCS and also to reduce uncertainty in related studies. While the true value of national FCS is immeasurable, our work should motivate future studies that explore new estimations to approach the true value by narrowing the uncertainty in FCS estimations on national and global scales.

Theoretical Considerations about the Steady State Combustion of Wood Char in a Bubbling Fluidized Bed Reactor

A theoretical study on the performance of steady state bubbling fluidized bed burners is presented using a simple mathematical model. The proposed model has pedagogical and practical advantages due to its simplicity. The calculations, whose results are plotted in several graphics, were based on data obtained in laboratory scale experiments. The experiments were carried out with wood chars and the model allows a proper evaluation of physical and chemical phenomena taking place inside the reactor, as well as a fast approach to the pre-design phase, before going towards more complex and time consuming numerical modeling. In the first part of the paper the steady state modeling is compared with the combustion of successive batches of char particles. Afterwards, the performance of a 1 m diameter bed operating from 700℃ to 800℃ is shown.