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WOOD ENERGY: 
PRINCIPLES AND APPLICATIONS 
 
 
 
 
 
 
 
 
 
Luiz Augusto Horta Nogueira 
Electo Eduardo Silva Lora 
 
 
 
 
 
 
 
2002 
 
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Translation from Portuguese to English by 
Adriana Costa Candal Lopes 
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“Light of sun swallowed by the leaf, 
translating it into a new green, into 
grace, into power, into light.” 
 
 Índia, Caetano Veloso 
 
 
“and everything will be born more beautiful 
so green makes with blue and yellow 
the link to color a grayed love” 
 
 Nem um dia, Djavan 
 
 
 
 
 
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Presentation 
 
For ages, energy, an essential asset for human activities, was mainly attained from plants, 
which through photosynthesis, patiently accumulate solar energy making it available to be used 
in any form or whenever it is desired. So, from the pre-historic caves that were warmed up and 
illuminated by fires until the 18th Century, firewood was practically the solely source of fuel for 
mankind. It was only after industrial societies had flourished, it was replaced, partially, with 
coal, petroleum, and natural gas, but today, it is still being widely used all over the developing 
world, which maintains its traditional energy practices. Owing to its historical primacy and the 
apparent modernity of the energy fossil sources, biomass energy is sometimes seen as old-
fashioned, waiting for more modern alternatives. Surely, this judgment is wrong. Bio-energy 
technologies have been evolving constantly and they are able to gather important economic and 
environmental advantages. The use of energetic biomass is an increasing factor of the 
improvement of energy system sustainability. 
 
The goal of this study is to present the techniques of biomass production and energy 
conversion, particularly considering lignocellulosic materials such as firewood, husks and straw, 
and the adoption of thermal processes for their suitability to end uses such combustion and 
gasification. Some years ago, Miguel A. Trossero, United Nations Food and Agricultural 
Organization (FAO), created the term Dendroenergy, that means “energy from trees” to renew 
the concepts and call more attention to these energy systems. Wood energy embraces the 
traditional use of firewood in household stoves, which have undergone great developed, as well 
as modern applications, either as firewood or residues, for electricity generation passing through 
a wide scope of technologies and capacities. 
 
The public targeted by this publication are undergraduate or graduate students of Forest 
Engineering, Mechanical Engineering, and Energy Engineering, as well Agronomy students, and 
also professionals of the energy and forestial areas who are interested in improving their skills in 
the field of wood energy, which is presented in its principal aspects and its most relevant 
applications already in use or still being developed to be used. In order to reinforce the correct 
consideration of these energy technologies in a feasible way, the fundamental economic and 
environmental conditions were included and commented, in addition to the technological 
aspects. 
 
The basic definitions, the present scenario and the perspectives of biomass utilization 
emphasizing the importance of this energy sector are presented in the first chapter. The second 
chapter presents a view of wood energy systems formed by an articulated system of productive 
components where solar energy flows either being wood or other matters for an end use, with a 
wide potential of integration and synergies. The following chapter is dedicated to biomass 
attempting to include and characterize all of the biomass energy potential sources, from forest to 
urban agro-industrial residues. The fourth chapter is dedicated to the elements and some 
applications of the biomass transformation processes until its final energy for the user. This can 
either be as heat or electricity for different kinds of consumers and employing technologies such 
as gasification and pyrolysis. In the final chapters it is intended to analyze the wood energy 
environmental, social and economical aspects, which are essential factors for the correct notion 
of its need. 
According to this study, the bio-energy, although treated in a wood energy oriented way, 
represents a remarkably challenging issue because of the extent of its relation to the environment 
and society, as well as its enormous diversity of cases and possibilities. Therefore, the authors 
did not have the pretension to write an encyclopedia about this subject, instead they tried to write 
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a study that could motivate the proposition and development of future projects and studies and, 
perhaps, new advances (discoveries). 
The first version of chapters 1, 2, 3 and 7 was elaborated by Professor Horta Nogueira 
during his internship as a Visiting Scientist in FAO, while the first version of chapters 4, 5 and 6 
was prepared by Professor Silva Lora. The close interaction between the authors during the 
revision of each chapter of the original manuscript made it seem that all of the chapters were 
written by “four hands”, embodying complimentary points of view and experiences. As direct 
predecessors of this work, we can mention the handouts of the Latin American Energy Planning 
Course that Professor Horta Nogueira taught for several years at Institute for Energy Economics, 
(Fundación Bariloche, Argentina), the books "Tecnologias de conversão energética da 
biomassa", "Pruebas de balance térmico en calderas para bagazo" and the chapter "Perspectivas 
da utilização da biomassa com fins energéticos" of the book “Tecnologia e Aplicação Racional 
de Energia Elétrica e de Fontes Renováveis na Agricultura”. These last books had Professor Lora 
as a co-author. 
 
We thank our colleagues Miguel Angel Trossero and Torsten Frisk for the suggestions 
and advices that greatly enriched the first edition of this work, particularly the second chapter. 
We also thank UNIFEI’s PhD students, Vladimir Melián Cobas, Flávio Neves Teixeira and 
Marcelo José Pirani, for without their help, it would have been impossible to issue the second 
edition of this book. We want to thank the drawer Messias Tadeu Salgado, who works at 
UNIFEI, for the splendid illustrations. We also thank the following institutions for the 
encouragement and support in the elaboration of the first version of this book (written in 
Spanish) and the publication of its first edition in Portuguese: FAO - United Nations Food and 
Agricultural Organization, ANEEL - National Agency for Electrical Energy, MCT – Ministry of 
Science and Technology, PNUD – United Nations Development Program. We also have to 
mention the support given by the Human Resources Program of ANP – National Agency of 
Petroleum (PRH-16 ANP/EFEI Petroleum and Energy Engineering) from which Professor Lora 
received a scholarship as a Visiting Researcher for a few years. 
 
Finally, we put ourselves at your disposal. You can contact us through our e-mail 
addresses for eventual reviews, opinions and suggestions: horta@anp.gov.br, electo@iem.efei.br. 
 
 
 
 
The Authors 
 
 
 6
Preface 
 
In spite of the success of “modern biomass” programs, among which the Alcohol National 
Program, which has been going on in Brazil since 1975 converting sugar cane biomass into high 
quality ethanol, the use of “traditional biomass” based on the deforestation of native forests is 
still significantly widespread all over the world. 
In 1988, despite the existence of a reduction trend, “traditional biomass” still corresponded to 9.5 
% of the world’s energy matrix, regardless of all the widely known negative environmental and 
social impacts. 
“Modern biomass”, in turn,includes the use of agricultural, forest, urban and rural residues for 
heat and electricity generation, and in the transport sector as well. 
This “modern biomass” is included in the category of the “new renewable energies”, together 
with wind, solar and geothermal energy, and the energy coming from small hydropower plants 
and from the tides, whose participation in the world’s energy matrix is highly desirable and must 
be encouraged because of all their well-known strategic, environmental and social advantages. 
Within this scenario, the contribution of the present text, which was written by two well-known 
experts in the area, Electo Eduardo Silva Lora and Luiz Augusto Horta Nogueira, is irrefutable. 
This publication analyzes the most diverse aspects of production, conversion and the use of 
“energy from forests” – or “wood energy” – spreading the idea that this energy can certainly be 
used aiming at contributing towards a sustainable development for the world. 
 
Suani T. Coelho 
Professor in the Graduate Interunit Program 
Executive Secretary of CENBIO - National Biomass Reference Center 
 
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WOOD ENERGY: PRINCIPLES AND APPLICATIONS 
 
Index 
 
 
Preface 6
1. Introduction 8
 1.1. Definitions and concepts 8
 1.2. The meaning of Wood Energy 11
 1.3. Evolution and perspectives 15
 References 17
 
2. Wood energy systems 18
 2.1. Wood energy system structure 18
 2.2. Optimized wood energy system implementation 20
 References 23
 
3. Wood energy resources and fuels 24
 3.1. Photosynthesis 24
 3.2. Wood energy resources 30
A. Natural forest 30
B. Energy forest 31
B.1. Forestry 31
B.2. Annual crops 32
B.3. Transitional crops 35
C. Aquatic phytomass 35
D. Residues and biomass by-products 35
D.1. Agricultural residues 36
D.2. Forestial residues 37
D.3. Agro-industrial residues 37
D.4. Urban residues 39
3.3. Restrictions on biomass resource availability 40
3.4. Wood energy resources characterization 40
References 44
 
4. Basic processes for wood energy conversion 45
4.1. Biomass combustion 46
4.2. Biomass gasification 53
4.3. Biomass pyrolysis 55
References 59
 
5. Wood energy technologies 61
5.1. Pre-processing of wood energy resources 61
A. Size reduction 61
B. Drying 62
C. Densification 65
5.2. Biomass direct combustion 67
A. Residential systems 67
B. Industrial Systems (Process heat generation) 70
B.1. Grates and Combustion systems 71
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B.2. Boilers 73
B.3. Boiler efficiency 76
5.3. Applied gasification 80
A. Gasifier comparison 83
B. Gasifier efficiency 84
C. The gas quality issue 89
5.4. Charcoal production 91
5.5. Fast pyrolysis and bio-oil attainment 93
References 94
 
6. Wood energy applications 98
6.1. The use of by-products for heat generation in ovens and boilers 98
A. Coffee husk ovens 98
B. Rice husk gasification systems for air heating in rice drying 99
C. Brick kilns that use sugar cane bagasse 100
6.2. Wood energy and electricity generation 102
A. Small and medium capacity systems 104
B. Biomass gasification for large scale electricity generation 109
6.3. Advanced Technologies: gas microturbines, Stirling engines, fuel cells 
and hybrid systems 117
6.4. Wood energy and the iron and steel production 137
References 139
 
7. Wood energy and social and environmental issues 141
7.1. Energy x Food 141
7.2. Wood energy and job offer 143
7.3. Wood energy and the environment 143
A. Environmental effects during the agricultural phase 144
B. Environmental effects during the conversion phase 144
B.1. Direct combustion systems 145
B.2. Other wood energy processes 149
7.4. Wood energy and climate changes 151
A. Basic parameters 153
B. Sequestration and replacement of the carbon emissions 155
References 158
 
Appendix: Some links about bioenergy at internet 
 
 
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1. Introduction 
 
The definitions regarding biomass energy use are presented briefly in this chapter, 
and it was given a particular emphasis on wood fuels. In addition, a concise illustration of 
its present importance in different regions of the world concerning forest and energetic 
scopes was also demonstrated, showing its historical evolution and the perspectives for its 
utilization. 
 
1.1. Definitions and concepts 
 
The term biomass comprises the vegetal matter generated through photosynthesis 
and its derivatives such as forest and agricultural residues, animal waste and the organic 
matter that is contained in industrial and urban waste. This matter contains chemical energy 
that comes from the solar radiation energetic transformation and can be directly released by 
means of combustion or converted into other more adequate energy sources - alcohol or 
charcoal, for example - through any other process. Using nearly 1% of the total incident 
solar radiation on Earth, it can be estimated that nearly 220 x 109 tons of biomass (dry 
basis) are annually produced through the photosynthesis process, which is equal to 2 x 1015 
MJ, that is, 10 times more than the global energy consumed in our planet every year 
(SMIL, 1985). The total existing energy on the earth’s vegetal cover, including tropical and 
temperate woods, is estimated to be about 100 times the present energy consumption on 
earth throughout the year. Naturally, only one part of this enormous amount of energy can 
be used to satisfy human needs, however these numbers can give us a notion of how 
important the biomass energy potential is. 
The biomass energy resources can be classified in several different ways, 
nevertheless, one must recognize that biofuels are associated with biomass energy flows, 
and they can be presented in three major groups according to the origin of the matter they 
are constituted of. This way, there are biofuels coming from wood (wood fuels), fuels from 
non-forest plantations (agricultural fuels) and urban waste. Table 1.1 shows the biofuels 
classification, which will further be described in detail. It is a simple description presenting 
the resources in such a way as to compare the typical treatments used in energy and forest 
studies and comparing data from different sources. 
- wood biofuel (wood fuel): it basically includes firewood, which can be produced and 
obtained through a sustainable way out of cultivated or native forests. It is necessary to 
respect the limits that make the natural regeneration of such forests possible. Firewood 
can also come from deforestation of native formation with the purpose of getting land 
for agricultural or cattle activities. These fuels can also be obtained through activities 
that process or use wood not exclusively for energy purposes, as for example saw-mills 
and cellulose industries (Table/Fig. 1.1). The energy content of this biomass class is 
basically associated with the cellulose and lignin contents of the biomass in question 
presenting, in general, low moisture and preferably adopting thermochemical 
transformation routes for its end use as the combustion or carbonization systems. Other 
more complex examples of forest-origin fuels are: charcoal, black liquor (a by-product 
from the cellulose industry) and methanol or methyl alcohol that is produced out of 
wood. 
 
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Table 1.1 - Biofuel classification 
1st level 2nd level Definition 
Wood Biofuels Direct wood fuels Wood produced with energy 
purposes which is direct or 
indirectly used as fuel 
(wood fuels) Indirect wood fuels It includes solid, liquid or gaseous 
biofuels that are deforestation sub-
products and the ones resulting 
from forest wood “utilization” the 
wood industrial processing with 
non-energetic purposes. 
 Recycled wood 
fuels 
Wood that is direct or indirectly 
used as fuel. It comes from socio-
economical activities that use 
forest-origin products 
Non-forest BiofuelsFuel from energy 
crops 
Energy plantation 
fuels 
Typically solid and liquid fuels 
which are produced in annual 
crops such as the sugar cane 
alcohol. 
(agricultural fuels) Agriculture by-
products 
Mainly crop residues and other 
sorts of cultivation residues such 
as trash and leaves 
 Animal by-
products 
Basically poultry, cattle and swine 
manure 
 Agro-industrial by-
products 
Basically by-products from agro-
industries such as the sugar cane 
bagasse and rice husks 
Urban waste Solid and liquid residues produced 
by cities or villages 
 
- Non-forest biofuels (agrofuels): They are typically produced from annual crops. 
They present more moisture than the forest biofuels. In general, its use demands a 
conversion to another more suitable energetic product first. Within this class, for 
example, there is the sugar cane of which calorific value is associated with the 
content of cellulose, starch, sugars and lipids that determine the sort of energy 
product that can be achieved. Several kinds of energetic by-products, which come 
from activities related to the production and processing of agricultural products and 
are sometimes in an incorrect and depreciative way named residues, can also be 
denominated biofuels. As examples of these agricultural by-products there are: the 
ones produced at agricultural properties that are directly associated with the 
vegetable production; animal-origin by-products, basically several sorts of manure 
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and agro-industrial by-products resulting from the processing of agricultural 
products, such as sugar cane bagasse, rice husks or coffee hulls, etc. 
 
 
Figure 1.1 – Wood biofuel fluxes 
 
- Urban waste: Although this category includes matters coming from diverse 
origins, such as plastic and metal, most part of the garbage and practically all of the 
organic matter from the sewage waters is represented by biomass. The use of these 
residues with energy purposes may signify a considerable environmental benefit and 
a gradual elimination of contaminant matter, which almost constantly causes 
increasingly difficulties in cities and villages. The process of converting them into 
other energy products is basically defined according to the moisture level, where the 
anaerobic biodigestion and other direct combustion systems can be applied. 
 
 It is worth observing that, in general, the fuels can be considered to be primary 
when they correspond to matters or products obtained directly from nature, as firewood and 
sugar cane for example; or secondary which is the case of the fuels resulting from primary 
energetic fuel conversion processes. The charcoal produced from wood and the alcohol 
produced from fermentable substances are included in this class. 
 
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 Some kinds of biomass are difficult to be classified, such as vegetable residues in 
the initial phase of their transformation into mineral coal, or even the vegetable oils 
produced from products derived from trees such as the oil palm tree, which could be 
considered as a wood fuel or an “agro-fuel”. There are two other ways to classify biomass: 
taking the technological routes to be adopted for the biomass use into account or 
considering its development level. According to this last classification concept the 
traditional biomass energy can be found (firewood, charcoal, rice trash and husks and 
vegetable residues and animal waste, which are well known and widely used resources) and 
the modern bioenergy (associated with wood industrial utilization residues, the sugar cane 
bagasse, the energy plantations and the urban residues either in a more restrict diffusion or 
in a development phase). However, besides looking for a perfect classification, it is 
important to have in mind, whenever it is possible, the origin and the utilization of a certain 
biofuel, so that it is possible to recognize its impacts and potential. 
 
 The term wood energy is associated with the lignocellulosic energetic biomas in 
general and its by-products, chiefly in a renewable basis. The technical, socio-economical 
and environmental aspects related to forest production, the forest and similar resources pre-
processing, and their eventual conversion into other forms of final energy and, at last, their 
effective utilization are considered to be wood energy themes. Because of their affinity with 
technologies of firewood utilization, other non-wood related products having similar 
composition are also part of wood energy themes such as the bagasse and several residues 
or agricultural and agro-industrial by-products. The present study is basically dedicated to 
wood energy. It tries to analyze the information starting at its resources passing through the 
technologies of conversion into other sources of final or secondary energy. 
 
 1.2. The meaning of Wood Energy 
 
 It is well known that the quality of the available information about biomass energy 
use can be significantly improved. The frequent inexistence of commercialization regular 
systems and institutional bases, which are responsible for attending and analyzing the 
behavior of biomass markets, with a few exceptions, makes the data related to the total and 
sectional wood fuel demands, in their various forms, to be a result from estimates or 
disintegrated studies. Leaving these limitations aside, it is possible to carry out some 
analyses of the present situation based on forest statistics and regional studies developed by 
FAO considering different kinds of wood fuels and trying to evaluate their relative 
influence. 
 
Table 1.2 shows data regarding 1995. As it can be observed, the volumes of 
consumed energetic fuel associated with wood are quite important, either in terms of its 
participation in the energy offer or as a forest production percentage. Most part of this 
consumption takes place in Asia, and about one quarter of the total consumption 
corresponds to developed countries. The composition of this fuel resource, i. e., the product 
composition of biomass consumption in different regions, is shown in Figure 1.3 using 
absolute volumetric units (SCM, solid cubic meter) and Figure 1.4 displays the percentage 
of each product, where it is possible to notice that in the developed countries most part of 
the wood energy reaches the consumer as a wood-industry by-product. 
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In order to transform the distinct product flows into common units, charcoal, for 
example, it was adopted a productivity of 165 kg charcoal for one solid cubic meter of 
firewood (ONU, 1991), and for black liquor it was considered that each ton of cellulose 
produced by means of chemical pulping generates an amount of liquor that corresponds, in 
energetic terms, to 0.44 solid cubic meters of firewood. For the transformation of the wood 
volumetric unit into energy, a density of 725 kg/SCM and a calorific value of 13.8 MJ/kg 
were considered. (ONU, 1991). These values result in 1TJ (terajoules) for each 100 SCM, 
that is, 10 GJ (gigajoules) for SCM. 
 
Table 1.2 – Wood energy demand and importance (FAO, 1998) 
 
Region 
Wood fuel total demand Wood energy importance 
 1,000 SCM PJ Energy production, % 
(1) 
Forest production, 
% (2) 
Developing countries - total 1,763,262 17,633 15 80 
 tropical total 1,368,439 13,684 26 84 
 non-tropical total 394,822 3,952 6 65 
Africa 486,248 4,862 35 89 
 tropical 464,077 4,641 75 91 
 non-tropical 22,171 222 3 53 
Asia 1,002,846 10,028 12 81 
 tropical 654,221 6,542 23 85 
 non-tropical 348,625 3,486 7 70 
Oceania 5,804 58 52 56 
Latin America and the 
Caribbean 
268,364 2,684 12 66 
 tropical 244,338 2,443 13 69 
 non-tropical 24,027 240 7 48 
Developed countries – total 536,754 5,368 2 31 
Europe and Israel 194,653 1,947 3 33 
The former USSR 42,585 426 1 27 
The USA and Canada 272,438 2,724 3 29 
Oceania27,079 271 1 36 
World 2,300,016 23,000 7 59 
(1) In relation to the total primary energy, (2) In relation to the total forestial extraction 
 
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Figure 1.2 – Wood energy demand distribution, data from 1995 (FAO, 1998). 
 
 
 
Figure 1.3 – Wood energy offer composition, absolute values, 1995. 
 
 Another way of showing the importance of the wood energy is through demand 
specific indicators in relation to the population and to the economic product (Table 1.3). 
Figure 1.5 shows the relation between bioenergy consumption (as the percentage of total 
energy consumption) and the development level of different countries, expressed by the 
Human Development Index – HDI. This indicator considers, in an integral way, the 
percapita income, life expectancy, percentage of adult alphabetization and the percentage of 
the population participating in educational programs. 
As we can see in figure 1.5, it is possible to distinguish four country groups: 
I. Countries with an intensive biomass utilization for domestic subsistence use. (mainly 
low development countries); 
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II. Countries with a predominant use of fossil fuel energy (highly and medium developed 
countries); 
III. Medium and high development countries with an intensive biomass use, usually agro-
industrial residues for energy applications (modern biomass). These are countries such 
as Brazil, Costa Rica, Chile, Colombia, Cuba, Thayland and others; 
IV. Highly developed countries, with a considerable percentage of bioenergy use, as a 
consequence of incentives and taxes. In this group we can find Sweden and Norway. 
 
In global terms, the wood fuel specific annual demand is equal to 4 GJ/per 
capita.year, that is, 0.4 SCM/per capita.year, with a wide variation among distinct regions. 
 
 
 
Figure 1.4 – Wood energy offer composition in percentage, 1995. 
 
Table 1.3 – Wood energy per capita consumption indicators. 
 Energy Forest production 
Region from wood from other 
sources 
for energy for other 
uses 
 GJ/ person.year SCM/person.year 
Africa 6.7 12.3 0.716 0.092 
Asia 3.1 22.0 0.282 0.068 
Oceania (developing) 8.8 8.0 0.876 0.702 
Latin America and the 
Caribbean 
5.6 40.0 0.578 0.293 
Europe and Israel 3.4 121.7 0.249 0.508 
Former USSR 1.5 106.4 0.146 0.397 
The USA and Canada 9.3 334.7 0.842 2.020 
Australia, New Zealand 
and Japan 
1.8 159.8 0.224 0.406 
 16
 
 
 
Figure 1.5 – Bioenergy consumption and development level (UNDP, 2002). 
 
1.3. Evolution and perspectives 
 
The biomass, essentially as firewood, was undoubtedly the first energetic source 
used by mankind. This was based on the fact that the control of fire production techniques 
was initiated at the beginning of the Paleolithic period, i.e. nearly 1.4 million years ago. At 
that time, in Africa and Asia, the first bonfires appeared in caves where our ancestors used 
to live. Another important technology for biomass use is the alcoholic fermentation. It 
probably appeared in Egypt at the end of this period, about 28,000 years ago. With the 
improvement of firewood combustion systems and the progressive use of charcoal, 
firewood became the energetic basis of the ancient civilization allowing the development of 
important activities such as pottery and glass manufacturing and metal casting. 
It was with the Industrial Revolution in Europe and later in the United States, 
especially during the 19th Century, that the huge expansion of fuel demand could no longer 
be satisfied by the solar energy accumulated in the plants, so the utilization of carbon and 
petroleum oil is justifiable. In fact, the transition to these fuels was the only way out left for 
a lot of countries after they had intensely and irrationally exploited their woods for 
centuries, causing great forest extensions, mainly in Europe, to vanish. However, even 
though the fossil energy sources has continually penetrated into the industrialized society, 
at present the main source of energy in several countries is still the biomass, firewood 
above all, which inclusively can result as a by-product from non-energetic wood activities. 
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Nearly half of the Earth’s population depends on biomass for cooking, heating and lighting. 
This shows that the use of wood energy has, recently, also started to be considered as a 
modern and clean form of energy supply and it has increasingly been adopted by some 
industrialized countries. 
 The revival of the interest in bioenergies and the valorization of the biomass as a 
modern energy source sprang up in the seventies and it shows two quite distinct phases. 
Initially, with the strong rise in petroleum oil prices in 1973 and 1979, biomass was 
considered to be an economically interesting alternative to satisfy thermal energy demands 
for industries and small and medium capacity power plants, and in some cases as a source 
of fuel for vehicle alternative engines. During this period, the major justification was 
bioenergies smaller prices when compared to conventional energy. However, in 1985, the 
prices of petroleum oil went back to its initial levels, so that the interest in these new or re-
discovered sources of energy supply (bioenergies) was significantly reduced. 
The second phase of this expansion and interest in the energetic biomass appears in 
the nineties with the development of advanced transformation technologies and with the 
definitive incorporation of the environmental issues into the discussions about energy. 
Within this new scenario biomass starts to be considered as an opportune way of satisfying 
the energy demand due to a wide set of reasons such as a minor environmental impact and 
its renewability, the possibility of generating jobs and the possibility of making regional 
economies more dynamic, in addition to the strictly economic factors. 
 The inevitable nexus between biomass energy and agricultural activities, at the same 
time that it imposes a greater complexity on these energetic systems, may also be translated 
into new synergies and important positive externalities. Such aspects are been paid much 
more attention and they constitute the new favorable arguments allowing the biomass to 
show, at present, a collection of very interesting realizations in different countries what is 
an indication of new opportunities. According to HALL (1995), some of the successful 
programs that can be pointed out are: the utilization of charcoal within the steel and iron 
industry and the automotive alcohol program in Brazil, the massive diffusion of the biogas 
in China, the implementation of energy forests and the bioelectricity production in the 
USA, the utilization of wood with energetic purposes in Austria and Sweden, the use of 
agricultural residues in Great Britain and the Netherlands, the eucalyptus plantations in 
Ethiopia and the use of sugar cane bagasse in the Mauritius Islands among many others. 
What is certain is that some of these programs have been facing difficulties, but, 
undoubtedly, they show results and an important feasibility in many senses. 
 
 Biomass is not a panacea, nor can it be adopted as the only single solution for the 
wide diversity of energy systems situations, but unquestionably it is an important 
alternative to be considered. By evaluating the new prospects of bio-energy expansion 
within the renewable sources boundaries, JOHANSSON et al. (1992) estimate that the 
biomass produced in a sustainable way and with modern transformation technologies could 
provide nearly 17% of the electricity and 38% of the direct fuel consumption in the world 
in 2050. 
 Fisher and Schrattenholzer (2001) evaluate the world bioenergy “economic” 
potential in 1990 as 225 EJ (5.4. 105 toe), from which only 46 EJ were used, corresponding 
to 20.4 %. For the year 2050 this potential is estimated as 370-450 EJ (8.8 – 10.8.105toe), a 
value equivalent to the present total world energy consumption in a year. 
 18
 Bioenergy potential is expressed by toe units (tons of oil equivalent). This is a 
hypothetical fuel, realeasing as burned a quantity of energy of 41,868.00 MJ per kilogram. 
 An interesting example is the new scenario of biomass demand. In Brazil this 
energetic source in its different forms represents about 20% of the total energy 
consumption at present. Firewood consumption in the Brazilian household sector has been 
decreasing along the last decades, specially because of the intense urbanization process 
inasmuch as the former consumers from the rural areas have moved to the cities, 
consequently demanding petroleum derivatives. However, this firewood use reduction is 
being compensated by the expansion of biomass modern uses. This transition is observed in 
other countries as well, but Brazil represents one of the cases in which the modern use of 
biomass shows some of the best results, in a short cycle for sugar cane or a long cycle for 
forest resources, showing updated industrial systems that are based on these resources as 
fuels, as well as reducers in iron and steel industries. It is this type of context that 
ROSILLO-CALLE (1987) denominate as “biomass society”, and it can, with the necessary 
adaptations, be considered as an alternative for the sustainable development. 
 
 
References 
HALL, D.O.; HOUSE, J., 1995, “Biomass: an environmentally acceptable fuel for the 
future”, Proceedings of the Institution of Mechanical Engineers (Part A: Journal of 
Power and Energy) Vol. 209(A3), London, pp.203-213, 1995. 
JOHANSSON, T.B., KELLY, H., REDDY, A.K.N., WILLIAMS, R.H., 1993, “Renewable 
fuels and electricity for a growing world economy: defining and achieving the 
potential”, in: .B.Johansson, H.Kelly, A.K.N. Reddy, R.H.WIlliams, L.Burnham 
(ed.). Renewable Energy: Sources for Fuels and Electricity, Island Press, 
Washington D.C., pp.1-72, 1993. 
FAO/ Forestry Department, WETT - Wood Energy Today for Tomorrow, Regional Study 
for OECD and Eastern Europe, prepared by van den Broek, R., Part A, preliminary 
version, FAO/FOWP, Rome, 1996. 
FISHER, G., SCHRATTENHOLZER, L., “Global bioenergy potentials through 2050”, 
Biomass and bioenergy, vol. 20, pp. 151-159, 2001. 
ONU, Department of International Economic and Social Affairs, Energy Statistics: a 
Manual for Developing Countries, Studies in Methods, Series F, No 56, United 
Nations, New York, 1991. 
ROSILLO-CALLE, F., 1987, “Brazil a biomass society”, in: Hall,D.O., Overend,R.P., 
(Ed.), Biomass: regenerable energy, John Wiley, London, pp. 329-348, 1987. 
 
SMIL,V., General Energetics, John Wiley, New York, 1985. 
 
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	Translation from Portuguese to English by
	Índia, Caetano Veloso
	Nem um dia, Djavan
	Presentation
	Preface
	Suani T. Coelho
	Direct wood fuels
	Recycled wood fuels
	Urban waste
	Region
	Energy