Capitulo 7F

Prévia do material em texto

7. Wood energy and social and environmental 
issues 
 
 The natural, technological and economical aspects associated with wood energy 
were presented in the previous chapters. In this chapter, the approach of other judgement 
elements is searched in order to evaluate the advantages and the requirements pertaining to 
this energy technology in a broader way. Therefore, the social aspects related to 
workmanship needs, as well as the possible social and environmental impacts caused by 
wood energy systems throughout the region, country or planet must be considered. 
 
 Energetic biomass has quite interesting features, which are different from the 
other traditional sources of primary energy such as petroleum, coal, etc. Biomass has its 
origin in the photosynthesis, converting the dispersed solar radiation that is into the vegetal 
matter and on the ground. This indicates the suitability of biomass, which can be used in 
decentralized systems with reduced capacities. The option for centralized systems with 
biomass may not be viable, because of the transportation and distribution costs. The 
political aspect must also be mentioned: energy means, undoubtedly, power and, therefore, 
the generation and distribution of energy in isolated systems means distributing, in some 
sort of way, power and decision-making capacity. Yet, in cases where centralized solutions 
were adopted, biomass features themselves have not allowed an energy concentration. 
 
 In general, energetic biomass can also be characterized regarding its role within 
the folk cultural context, especially when it is compared to other sources of energy 
considered to be unconventional, such as solar, wind and nuclear energy. Considering 
agriculture, the use of firewood and charcoal are well-known technologies and, this way, it 
is part of people’s culture. The shocks and troubles begin when recent technologies of 
energetic biomass conversion for large-scale production of methanol and ethanol are 
thought about. Once more, in this sense, the difficult biomass suitability to large-scale 
schemes must be remembered. 
 
 7.1. Energy x Food 
 
 Once wood energy systems are almost always conceived to use local fuel supply, 
a particular aspect of wood energy, which suggests great interest for the countries that are 
energetically dependent on others, is its self-sufficient character and that is promotes 
national security. However, it is necessary to observe that the external dependence degree 
is not determined by the level of energy importation only. It is essential for the economic 
and social costs of wood energy to be justifiable, as well as the adoption of a coherent 
technological profile regarding the country and the region. This way, if the energy 
production directly affects the social stability reducing food offer and increasing inflation, 
its advantages become negative. 
 142
 
 Energy and food are man’s basic needs, and they are associated from their 
production till their consumption. Nevertheless, energy and nourishment may confront 
each other because of the use of scarce resources such as capital, qualified labor and 
cultivable lands. On the other hand, the time consumed by people to get firewood may 
imply the sacrifice of maintaining their own green garden or another activity. The 
challenge is, effectively, in rationalizing the energy and food producing systems, so that 
they could be complementary components, not individual elements of planning. 
 
 It is important to notice that many countries do not produce enough food to 
provide for their population needs. Consequently, they resort to importation, and 
besides, developing countries are also frequently energy importers. Paradoxical as it 
seems, money and financial resources to import food and energy are obtained through 
the exportation of primary goods, which, in most of the cases, are agricultural products 
such as coffee, tobacco, banana, sugar, soybeans, etc. Over the last few years, it was 
observed that the price of the exportable agricultural goods have continually lost their 
exchange power face the energy costs. A great effort is not necessary to observe that the 
context is not favorable to the replacement of the binomial agricultural product exports 
– energy imports by the local energy production. This transition is not a simple one, and 
it is affected by several economic, social and political requirements among which the 
external debt and the whole society’s force and interest complex can be highlighted. 
 
 On the other hand, the issue of agricultural land availability is related to a triple 
pressure, for this land must produce agricultural goods for internal consumption, 
exportation and energy, where the internal market is the weakest element. It is necessary to 
identify the interests and promote, within the nation’s real priorities, a land use attending 
these multiple purposes. Some times, together with the implementation of a biomass 
energy program, it is advisable to implement a global and objective agricultural policy to 
increase productivity and ensure the profitability of traditional crops, as well as try to 
cultivate energy crops in marginal areas. 
 
 One must not forget that the use of the natural energy offer to attend large scale 
energy and food needs of the countries in a sustainable way goes through two great 
questions: how can the humid tropic be used in a sustainable and efficient way, and how 
can the arid areas be properly used and recuperated? It is important to incorporate the 
marginal lands in a productive way. However, this must be done in an environmentally 
healthy way. From the answers that can be achieved for these questions, the possibilities of 
biomass energy must be significantly broadened. 
 
 One of the ways to solve the energy-food dispute locally is the so-called 
Integrated Systems, which try to associate energy production out of biomass with the 
production of non-energetic agricultural and forest products. Taking wood energy into 
account, this is the proposal of the agro-forest systems when the energy from wood is 
considered as one of the multiple applications of trees and when all the wide benefits of 
planting trees are spread to other rural activities, such as erosion control, shadow and 
shelter for animals, fruit supply, wind protecting curtains, ground water stabilization, 
etc. 
 
 
 143
 7.2. Wood energy and job offer 
 
 One of the biomass energy features that is always mentioned is its intensive use 
of labor, usually of low qualification. In fact, the diverse operations of harvest, 
transportation and processing need an elevated number of workers, which is higher than 
the needs of traditional energy production. For instance, in order to produce 1 PJ of 
energy out of petroleum sub-products, the stages of extraction, production and refining 
require about 8 men/year. For the wood energy systems whose goal is the production of 
solid fuels in the developing countries, this index varies from 750 to 1.000 men/year, 
that is, a need for workmanship, which is a hundred times higher than for petroleum. It 
must be observed that this labor demand is, in general, seasonal, for it is conducted by 
the productive agricultural cycles. However, according to studies carried out in Chile 
(CIPMA, 1985), even at simple conditions of harvesting firewood for household use, it 
is estimated that for each PJ about 60 men/year are necessary, and because of the 
distance between the gathering and the consumption spots, between 260 and 1,330 
hours/man may be annually necessary for each household for firewood supply only. 
 Table 7.1 shows the indicators of labor demand for electricity generation 
comparing the different kinds of systems based on wood energy to the systems based on 
fossil energy (HEKTOR, 1992, apud FAO, 1996). According to this table, it is observed 
that for the generationof one electric energy PJ, between 8 and 73 men/year are 
required, that is, between 0.2 and 1.7 jobs per MW of capacity for a plant with a 
capacity factor of 75%. Data of real wood electric systems operating in Brazil with 
steam machines using sawmill residues and a total capacity of about 1 MW presented a 
labor demand of approximately 10 men per installed MW (NOGUEIRA e WALTER, 
1995). 
 Regarding the large-scale production of charcoal with casting purposes, 
including forest and conversion activities, the generation of jobs will depend on the 
adopted technology. Taking the Brazilian conditions into account, where nearly 8 
million tons of charcoal are produced annually, it is observed that for traditional 
practices, with the exploitation of native forests and the use of low efficiency ovens, 15 
men/year are required for an annual production of 1,000 tons. Nevertheless, considering 
more efficient methods, with eucalyptus plantations and higher capacity ovens, this 
same production is accomplished with 10.8 men/year (MEDEIROS, 1995). 
 
 7.3. Wood energy and the Environment 
 Along these sketches and in different opportunities, the importance of 
considering the ecological restrictions related to the energetic use of biomass was 
mentioned. The effects upon the environment take place during the agricultural 
production, the conversion and the end use. It must be observed that among the several 
technologies and procedures for the use of biomass, there are interesting options 
regarding environmental quality preservation, such as the recycling systems of 
industrial residues and municipal solid waste with anaerobic digesters. 
 
 
 
 
 
 
 144
 
Table 7.1. Direct jobs associated with electric generation (HEKTOR, 1992, apud FAO, 
1996). 
 Activities 
Employed system Cut Shredded Local 
transport 
Truck 
transport 
Electric 
plants 
Manage- 
ment 
Total 
 man.year/PJ 
Electric generation in 
sawmills 5 1 2 8 
Generation with 
recovered wood fuels 5 3 1 4 13 
Cogeneration in paper 
and cellulose 
industries 
- 6 8 11 15 1 4 34 
Intense wood electric 
plant in MO 38 20 5 5 1 4 73 
Wood electric power 
plant, mechanical cut 5 15 5 5 1 4 35 
Thermal power plant 
with agricultural 
residues 
4 8 8 1 2 23 
Thermal power plant 
with mineral coal 8 
 
 A. Environmental effects during the agricultural phase 
 
 Most of Latin American countries show the negative impacts of a disordered 
and irrational exploitation of their natural forest reserves that has been taking place for 
centuries. The effects, such as erosion, soil compactation, water stream reductions and 
soil nutrient removal, are catastrophic. One of the consequences of these practices is the 
fertility reduction and, in some cases, the beginning of a desertification process. By 
using suitable forest management in each ecosystem, these effects can be avoided or, at 
least, greatly reduced without hindering the use of forest biomass. 
 
 The environmental impacts caused by energy plantations affect, mainly, the 
quality of the soil and water and the diversity of fauna and flora, and they occur due to 
inappropriate practices of intensive cultivation. The effects can be awfully serious, as 
for example, exhaustion of drinking water availability for the population. It is very 
important for the energy biomass plantations not to reproduce the same already known 
mistakes of traditional monocultures. The adoption of biological control against the 
sugar cane “burr” without the use of pesticides in part of the Brazilian crops can be 
mentioned. 
 
 B. Environmental effects during the conversion phase 
 
 Whatever is the process used to produce fuel out of biomass, there will always 
be the possibility of generating by-products and residues whose quantity and quality 
 145
will, of course, depend on the sort of biomass that is used, the fuel that is produced and 
the technology as well. The technologies to convert biomass into energy products must 
only be implemented when their negative effects on the environment are acceptable and 
proved to be as small as possible. 
 
 B.1. Direct combustion systems 
 
 The burning of firewood and agricultural residues in steam boilers and furnaces 
constitutes a potential source of atmospherical pollutants. The greatest emissions 
correspond to particulates (basically volatile ashes), and they depend on the kind of 
combustion system that is used, among other factors. Polluting gaseous emissions, when 
biomass or other agricultural residues are burned, are smaller than the ones when fossil 
fuels are used. The nitrogen oxides that are present in the combustion gases show much 
lower concentrations than when fuel-oil or natural gas are burned as fuels, as a 
consequence of a lower combustion temperature. The emission of sulfur oxides is very 
low as well, because of the small sulfur concentrations in the wood and agricultural 
residue ultimate analysis. Thus, one can say that during the operation of boilers and 
furnaces that use wood as fuel, the control of the emissions is generally limited to the 
installation of particulate separating devices. 
 
 The most commonly used particulate separators in biomass boilers are: 
 
Multicyclones: They separate the particles through the action of a centrifugal force 
caused by the tangential inlet and the rotation of the gas inside the cylindrical body of 
the cyclone, as it is shown in 7.1 and 7.2. This equipment presents a typical efficiency 
for particulate separation ranging between 85 and 90%. 
 
 
 
Figure 7.1 – Cyclone Separators: a) with tangential inlet and returning flow; b) with 
axial flow; c) with axial inlet and returning flow. 
 
Gas scrubbers: Their operation principle consists in washing the gas with water, and that 
is the reason why they also receive the name of wet scrubbers. Figure 7.3 illustrates the 
most commonly used types of scrubbers, which may be scrubbers with trays, spray 
towers and Venturi scrubbers. These systems tend to be more complex than the previous 
ones, however, their efficiency is higher, and the Venturi scrubber may reach 
efficiencies above 95%. Table 7.2 presents the gas scrubber design and operation main 
 146
parameters. Among these parameters, the cut diameter was introduced. It indicates the 
particle minimum diameter for which the separator operates with a 50% efficiency. 
 
 
 
Figure 7.2 – Multicyclone separator (SUYOTO AND MOCHTAR, 1995). 
 
Table 7.2 – Gas scrubber design and operation parameters 
Parameter Gas scrubber with 
trays 
Atomization tower Venturi 
scrubber 
Cut diameter (µm) 1.0 > 1.0 0.1 – 0.4 
Gas velocity (m/s) 1.0 1.0 – 1.8 40 – 150 
Pressure drop (kPa) 2 – 3 0.2 - 2 3 – 20 
Water/gas relation 
(l/m3) 
0.26 – 0.39 0.05 - 10 0.5 - 5 
Power consumption 
(kWh/1.000 m3) 
52 –130 14 - 52 78 – 312 
 
 
 
Figure 7.3 – Types of gas scrubbers 
 147
Electrostatic precipitators: in these systems, that may reach an efficiency of 99%, the 
particles pass through an ionic discharge between emitting and collecting electrodes. 
The particles are electrically charged being attracted by electromagnetic forces to the 
collecting electrode over which they are disposed. During the collecting electrode 
periodical cleaning, these particles fall in the discharge silo. The operation principles 
regarding these separators are shown in Figure 7.4, and Figure 7.5 displays the scheme 
of a real system. 
 
 
 
Figure 7.4 – Electrostatic precipitator operation principle. 
 
 
 
Figure 7.5 – Electrostatic precipitator scheme (Courtesy of ABB do Brazil). 
 
Baghouse filters: These devices use industrial cloth or fabric as a filter. The cloth is 
placed in the shape of cylindrical baghouses. The risk of fires, due to the intense 
dragging of particles,which are partially burned in the boilers, limits the use of this type 
of separator when wood and agricultural residues are used as fuel. Its efficiency 
regarding the separation of particulates can reach 98%. 
 
 Besides its own installation and operation costs, gas cleaning systems introduce 
an additional loss of pressure at the exhaust point of the combustion products, that must 
be as low as possible, for it directly affects the capacity of supplying air to the 
combustion and the thermal power of the system. 
 148
 The definite selection of the technology and the design of the particulate 
control system for a given application is a complex issue. It is necessary to consider 
factors such as: efficiency, desired final emission level, investment cost, operation cost, 
available space, etc. As a preliminary information the load and size of the particulates, 
the gas characteristics (temperature, presence of acid or basic compounds) and the 
emission standards in force must be known. Sometimes, factors such as water 
availability or the necessity of recovering the product favor the use of dry separators. 
Table 7.3 shows a qualitative comparison of the different particulate separators, which 
may be useful during their selection. 
 Table 7.4 displays the relative investment and operation cost values, 
considering the costs regarding the multicyclone as a reference. As it can be observed, 
the Venturi scrubbers are characterized by high operation costs. This is a consequence 
of the pressure drop caused by high flow velocities in the Venturi throat (up to 120 m/s). 
On the other hand, the electrostatic precipitator, which is the most expensive option 
taking the investment cost into account, has a low operation cost. 
 
Table 7.3 – Particulate separator qualitative comparison. 
System Advantages Disadvantages 
Cyclones − Low cost 
− Operation at high temperatures 
− Low maintenance cost 
(they don’t have movable parts) 
− Low efficiency, specially for 
small particles (5 to 10 µm) 
 
Gas scrubbers − They can treat combustible or 
explosive particulates 
− Particulate removal and 
absorption in the same equipment 
− Variable removal efficiency 
− Gas cooling 
− Corrosion 
− Secondary pollution 
(they produce liquid effluents 
that will need treatment) 
Baghouse 
filters 
− High efficiency 
− They may separate a wide 
variety of particulates 
− Modular design 
− Small pressure drop 
− Significant area 
− Baghouse damage because 
of high temperatures and 
corrosive gases 
− Risk of fires and explosions 
Electrostatic 
Precipitators 
− High efficiency 
− They can treat a big amount of 
gases with a small pressure drop 
− wet and dry separation 
− Wide range of operation 
temperatures 
− Low operation costs 
− High investment cost 
− Little flexibility 
− It occupies a lot of space 
 
 149
 
Table 7.4 – Investment and operation cost relative values for particulate separators 
Separator Investment cost Operation cost 
Multicyclone 1 1 
Atomization tower 2 1-2 
Venturi scrubber 2-3 3-4 
Core separator 5 3 
Baghouse filter 8-10 2-3 
Electrostatic 
precipitator 
10-17 2 
 
 Although each case presents conditions that favor one or another technology, in 
general, the most economical option, under all points of view, is the multicyclone, 
however its low efficiency must be considered. Today, the electrostatic precipitators and 
the baghouse filters are widely used as a preliminary stage. An improved version of the 
cyclone separators called core separator is being recently introduced. Its main 
advantage is to present efficiency levels that are comparable to the Venturi scrubber. 
 
The standards in force concerning particulate emission limits in different 
countries vary from values raging between 400 and 700 mg/Nm3 to values between 50 
and 120 mg/Nm3. The World Bank establishes 150 mg/Nm3 for its projects. These 
values are closely attached to the separation technology selected. Therefore, emissions 
that are under 350 mg/Nm3 are very difficult to reach by using multicyclones. On the 
other hand Venturi gas scrubber allow the attainment of emission values down to 80 
mg/Nm3. If emissions under 80 mg/Nm3 are intended to be achieved the only possible 
options are baghouse filters and electrostatic precipitators. Over the last few years, there 
has been an intense competition between these two separators in search for smaller 
emission values. Tables 7.5 and 7.6 show the emission factors (kg of pollutant/t of 
burned fuel) for biomass boilers. A summary of final emissions with different control 
devices is shown in Figure 7.6, displaying the effects of each system. The boilers that 
burn wood are characterized by particulate load values that range between 500 and 800 
mg/Nm3. But, when the bark of trees is burned, the load reaches values close to 4.000 
mg/Nm3. 
 
B.2. Other wood energy processes 
 
 Considering the case of charcoal manufacture, gaseous products, such as 
carbon monoxide and dioxide, and other liquid products with high commercial value, 
such as acetic acid, methanol and tar, are released in the environment. It is evident that 
the economic recovery of these products will depend on their production scale. New 
technologies for the recuperation of these highly harmful products are already available 
for the communities that are located nearby charcoal producing complexes. 
 
 Concluding, it is interesting to recall that the carbon dioxide that is generated 
by the energetic utilization of biomass is originated in the atmosphere through the 
photosynthesis phenomenon. So, biomass energy does not cause the carbon dioxide 
concentration in the atmosphere to increase. This is the issue of the next topic. 
 
 
 150
Table 7.5 – Particulate emission factors for biomass boilers (EPA, 1995). 
Source Particulate matter emission 
factor, kg/t 
Boilers that burn bark 
- Without controlling equipment 
- With a Multicyclone without ash re-
circulation 
- With a gas scrubber. 
 
21.36 
 
4.09 
1.32 
Boilers that burn wood and bark 
Without controlling equipment 
- With a Multicyclone without ash re-injection 
- With a gas scrubber 
- With an electrostatic precipitator. 
 
3.27 
2.45 
0.22 
0.02 
Boilers that burn wood 
- Without controlling equipment 
- With a Multicyclone without ash re-injection 
- With an electrostatic precipitator 
 
4.00 
1.91 
0.08 
 
Table 7.6 – Emission factors of nitrogen oxides (NOx), sulfur (SOx) and carbon 
monoxide (CO) for wood boilers (EPA, 1995). 
System NOx SOx CO 
 kg/t kg/t kg/t 
Boilers with cellular furnace 0.17 0.034 3.00 
Boilers with grate 0.68 0.034 6.18 
Boilers with fluidized bed 
furnaces 
0.91 0.034 0.64 
 
 Table 7.7 (BATTACHARYA et al., 2000) shows the average emission factors 
for different technologies using biomass in household or industrial sectors in several 
Asian countries. The values of the SOX emission factor in industrial boilers are much 
higher than the ones presented in Table 7.6 (EPA, 1995). BATTACHARYA et al. 
(2000) present data from different authors, showing that the reported values of this 
factor varies in a wide range that goes from 0.07 to 3.40 g/kg air dried fuel. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 151
Table 7.7 – Emission factors for different technologies using biomass with energy 
purposes (average values for several Asian countries calculated from data provided by 
BATTACHARYA et al., 2000), g/kg of air dried fuel. 
Fuel Equipment CO2 CO CH4 PTS SOX NOx
Traditional stove 1143.4 58.49 7.12 12.0 0.36 1.19 
Improved stove 1070.5 79.69 8.97 8.1 0.48 1.07 Firewood 
Industrial boiler 1389.3 22.77 10.15 13.01 0.37 2.8 
Traditional stove 1136.7 39.83 2.56 6.82 3.15 1.22 
Improved stove 1084.4 80.95 2.38 7.92 3.15 3.36 
Industrial 
boiler/bagass1048.7 7.93 2.44 29.00 3.40 1.20 
Agricultural 
residues 
Industrial 
boiler/rice husks 768.06 1.35 2.42 29.00 3.40 0.97 
Charcoal 
Household use 
(traditional and 
improved 
stoves) 
2253.7 166.02 7.94 10.29 0.437 2.76 
 
 7.4. Wood energy and climate changes 
 
The atmosphere transparence for thermal radiation is determined by its carbon dioxide 
(CO2) concentration and related to the temperature level of the heat source. This 
explains how, through the well-known Greenhouse effect, the solar energy passes 
through the air cover that surrounds the earth at the same time as the energy that is re-
irradiated throughout the Earth is partially retained by some gases, which the 
atmosphere is composed of (basically CO2). This way, Earth temperature would get 
higher than it would be if this phenomenon did not exist causing thermal conditions that 
are adverse to life. However, this is a delicate equilibrium, and it seems to be 
undergoing an alteration process. Due to the intense utilization of fossil fuels and 
deforestation processes, at least these are the main factors, the amount of 
atmospherically CO2 shows a significant increase inducing greater heat retention. In 
fact, there are already signs of global warming, which are getting even more evident, 
and uneasy perspectives of climatic changes are being expected with unpredictable 
consequences. 
 
 152
 
 
Figure 7.6 – Final emissions with different particulate control systems for biomass 
boilers. 
 
 
 In order to reduce the concentration of atmospherical CO2 which is associated 
to the use of fossil fuels, which are the most prominent production sources, basically 
these paths can be followed: reducing the emissions that are caused by fossil fuels and, 
on the other hand, capturing the carbon that is already in the atmosphere. As it is 
 153
presented in within this topic, wood energy is important in both senses and may have a 
more active role as a tool to face the risks of climatic changes. 
 
 A. Basic parameters 
 
 So as to evaluate the impact of wood energy in relation to the balance of 
atmospheric carbon, it is necessary to know the CO2 emissions which are associated 
with the biomass burn and the capacity of the forests to store the carbon as it is 
following shown. 
 
 Table 7.8 shows the carbon emission theoretical values during the burn of the 
main sorts of fuel and basically, they depend on their composition and calorific value. In 
this table, the value for “average fossil fuel” represents the quotient between emission 
totals and fossil fuel consumption throughout the world in 1995 (IPCC, 1996a). For 
firwewood, it was adopted a low calorific value of 13.8 MJ/kg, 30% moisture (dry 
basis) and a fraction of 48.8% as carbon in dry biomass. 
 
Table 7.8 – Specific carbon emissions for different fuels 
Fuel Theoretical emission Reference 
 t C/TJ 
Firewood 24.7 FAO/WEIS 
Solid fossil fuels 25.2 IPCC, 1996 
Liquid fossil fuels 18.5 IPCC, 1996 
Gaseous fossil fuels 15.0 IPCC, 1996 
Average fossil fuel 19.7 IPCC, 1996 
 
 Within real utilization conditions, the emission of carbon associated to the use 
of a fuel still depends on two additional parameters: the efficiency of its conversion to 
useful energy, that is, the ratio between the used heat and the total heat available, and 
the combustion efficiency, which is determined by the part of the fuel that is oxidized in 
the combustion reaction according to the following expression. As it was presented in 
the previous chapters, the systems that burn wood energy fuels are quite different from 
the systems that are typically adopted for fossil fuels, such as “fuel-oil” and the natural 
gas. Table 7.9 indicates some reference values for these efficiencies that may vary a lot 
from one case to the other. 
 
)8.7(Table
7.7) (Table Térmica Eficiência
Combustão de EficiênciateóricaEmissão
producedheat useful
emissioncarbon Effective ⎟⎟⎠
⎞
⎜⎜⎝
⎛= 
 
Table 7.9 – Thermal and combustion efficiencies (typical values) 
Fuel Combustion efficiency Thermal efficiency 
Fossil 0.98 0.85 
Firewood 0.95 0.80 
 
 The previous expression assumes that the produced useful energy is heat. 
When the final product is electricity, which is a frequent situation within a fuel 
conversion chain, the generation efficiency must be adopted, and CO2 emissions will be 
 154
a result because of the produced electric energy. It is evident that the lower the fuel 
utilization efficiency is, the greater the emission per produced energetic unit must be. 
 
 From the previous expression and the values from the tables, it is possible to 
determine the carbon emissions per unit of useful energy. Thus, for firewood and an 
average fossil fuel the emissions are 27.8 and 22.7 t of carbon per useful TJ, 
respectively. 
 
 Determining the amount of carbon that is stored in a forest is not an easy task. 
Taking into account the vegetal productivity within its theoretical levels, as it was 
presented in Chapter 3, one can find an annual fixation of almost 500t of carbon per 
hectare. In fact, the values that were found are much lower because of autotrophic and 
heterotrophic losses. Figure 7.7, adapted from WHITTAKER and MARKS (1975), 
present the carbon fixation data in natural forests in relation to the vegetal community 
age and pluviosity. 
 
 
 
Figure 7.7 – Influence of the vegetal community age and pluviosity on the amount of 
carbon that is annually accumulated in natural forests. 
 
Table 7.10 – Carbon storage for different vegetal communities (OPENSHAW, 1998, 
quoting BOWMAN, 1990). 
 Carbon storage 
vegetal cover Plant over 
the ground 
Plant under 
the ground 
Ground Total 
 t C/ ha t C/ ha t C/ ha t C/ ha 
Primary forest 90 45 200 335 
Secondary forest 70 35 150 255 
Pasture 18 9 150 177 
Typical agriculture 7 3 115 125 
 Note: Pluviosity – 1,500 mm/year; nitrosoils, carbon in the soil was evaluated 
as far as 1 m deep. 
 155
 
 
Figure 7.8 – Influence of the climate and pluviosity on the amount of carbon annually 
accumulated in natural forests. 
 Another way to make the carbon accumulation in vegetal communities evident 
is presented in Figure 7.8 and Table 7.10 (OPENSHAW, 1998). In order to estimate the 
mass accumulated in the roots, WHITTAKER and MARKS (1975), it is recommended 
to multiply the mass over the ground by: 1.33 for deep soils, 1.29 for average soils and 
1.25 for shallow soils. 
 
 B. Sequestration and replacement of carbon emissions 
 
 Based on data about the amount of carbon that is emitted when burning a fuel 
and the amount of carbon that can be stored in a forest formation, it is possible to 
evaluate the role that wood energy can perform and make a comparison between the 
handling of forests for energy production and the use of forests as permanent carbon 
sinks. In fact, in relation to emissions, the forests can be used in two different ways: in a 
passive way in order to sequestrate the atmospherical carbon, and in an active way to 
replace the emissions because of the fossil fuels. 
 
 The first possibility, the formation of permanent forests, aiming at carbon 
sequestration only, has been insistently presented as one of the most important actions 
to face the risks of climatic changes, and they are expected to take care of about 15% of 
the emissions that must be eliminated, according to the Kyoto Protocol (FCCC, 1997). 
Preliminary assessments indicate that the sequestration of such an amount of carbon 
from the air requires an annual growth of nearly 216 thousand ha of tropical forests. 
 
 The dimension of the risk of climatic changes imposes the consideration of 
forests as an active being, not only accumulating the atmospheric carbon, but also 
reducing emissions effectively. With the purpose of comparing the passive and activealternatives to employ the forests to mitigate climatic changes, the scenarios shown in 
Table 7.11 will be adopted, where two forests for energy production (high and low 
productivity) and one permanent forest kept only for carbon storage are considered. 
 
 
 
 
 156
Table 7.11 – Scenarios for comparison between permanent and handled forests in 
relation to carbon emissions. 
 Rotation AAI* Effects on the atmospherical 
carbon 
Scenario Annual 
fixation 
Storage 
 year T/ha/year t C/ ha/ year t C/ ha 
Handled forests, high 
productivity 
5 13.5 10 - 
Handled forest, low 
productivity 
10 8.1 6 - 
Mature tropical forest - - - 135 
* AAI is the average annual increase 
 
 Adopting simple logarithmic models to consider the growth of the natural 
formation and of the biomass accumulated on the ground to attend the condition 
presented previously, the analysis of the amount of biomass for the cases of a forest 
productively handled and the formation of a permanent forest can be developed. These 
results are exemplified in Figure 7.10, considering the amount of organic matter on the 
ground and on the ground for the handled forests separately. 
 
 
 
Figure 7.9 – Available biomass in the handled and permanent forests (example). 
 
 As it can be observed, there is an accumulation of carbon in the ground in 
handled forests, however, the most important feature is its production of goods in a 
sustainable way. Thus, when firewood is produced, the consumption of fossil fuels is set 
aside. Besides, in medium term periods, a certain amount of biomass is allowed to 
remain accumulated, producing the carbon sequestration effect that may be quantified, 
for example, by using an average moving value. The present model works with a period 
of 10 years for this variable. 
 
 157
 
 
Figure 7.10 – Carbon that was replaced and sequestrated in high productivity forests for 
firewood supply. 
 
Table 7.12 – Sequestrated and replaced carbon over 60 years of exploitation of a 
firewood forest. 
Scenario Low productivity 
forests 
High productivity 
forests 
Average Annual Increase, t/ha/ano 8.1 13.5 
Production cycle, years 10 5 
 Main results 
Sequestrated carbon in the soil, t/ha 18.7 19.3 
Sequestrated carbon over the ground, t/ha 21.8 19.8 
Total sequestrated carbon, t/ha 40.5 39.1 
Replaced carbon, t/ha 238.1 396.9 
Sequestrated and replaced carbon, t/ha 278.6 436.0 
 
 
 Based on the evaluation of the accumulated and/or produced biomass, it is 
possible to assess the amount of carbon that was involved, either as replacement or as 
sequestration. Figure 7.10 presents the data related to a high productivity forest while 
Table 7.12 summarizes the results for both studied scenarios. When the annual flows of 
replaced carbon, promoted by the continuing and productive handling of forests are 
compared with the permanent deposits in passive formations, it is evident that the 
advantages will depend on the analysis period that was considered. However, it is 
important to observe the significant superiority, in terms of atmospherical carbon 
balance, that a forest producing firewood presents for not very long periods facing 
another useless and static forest, which is compatible with situations of real utilization. 
 
 The advantages of wood energy facing the static sequestration of carbon are 
potentiated when electric energy production is analyzed. Let us think, for example, of a 
thermal power plant of 1 MW, with a thermal efficiency of 30%, capacity factor of 80% 
and able to consume mineral coal or firewood. When coal is used, about 2,160 tons of 
 158
carbon must be annually emitted. In order to have this carbon sequestrated from the 
atmosphere and fixed in trees, it is necessary to grow about 16 ha that over the 30 years 
of the plant life expectancy will reach 481 ha. This forest area must be endlessly 
preserved or until another solution for the problem of carbon increase in the atmosphere 
is found. When firewood is adopted as fuel, a forest area of 508 ha is required 
(assuming 12 t of dry firewood/ha/year) to produce, in a permanent and sustainable 
way, the fuel that is necessary for the electricity generation, replacing coal for a 
renewable fuel with pollutant emission reduction. In addition, the existence of such a 
forest producing firewood in a permanent way allows the identification, as an average 
value, of a biomass volume that can sequestrate the carbon, allowing the rescue of all 
the carbon emitted by a mineral coal conventional plant of 0.28 MW over a useful life 
of 30 years. 
 
 C. Carbon credit market and the clean development mechanism (CDM) 
 
 These issues, which have recently become part of international debates, are 
significantly relevant for the development of the use of biomass energy. They will be 
discussed briefly in this topic. 
The Carbon Credit Market was conceived as a consequence of the search for 
solutions for the global warming and the greenhouse effect. From a theoretical point of 
view, there is no doubt that the humankind will only survive in case they are able to 
conciliate the production of goods and services with environmental and social welfare. 
The adoption of the Clean Development Mechanism is an important step towards this 
direction. 
The Kyoto’s Protocol, presented in Japan in December 1997, proposes the 
beginning of a process to stabilize the emission of gases that cause the greenhouse 
effect. The Protocol divided the countries into two groups: 
 
Attachment I – industrialized countries, which produce large emissions of CO2 and 
Non - Attachment I – countries that have to increase their energy offer and, 
consequently, their emissions in order to attend their basic needs for development. 
 
The European Union and the 38 countries that are part of Kyoto’s Protocol 
Attachment I must have different reductions based on the emissions registered in 1990. 
These countries must achieve a net reduction in their emissions of 5.2% (Table 7.13). 
 
Table 7.13 – Kyoto’s Protocol emission reduction proposal (Acquatella, 2001) 
Countries and group of 
countries 
Emissions in 1990 (MtC) Kyoto’s goal 
USA 1.362 93% 
Japan 298 94% 
European Union 822 92% 
Other OECD countries 318 95% 
Eastern Europe 266 104% 
Former USSR 891 98% 
TOTAL 3.957 95% 
MtC (Million of tons of equivalent carbon) 
 
 159
The Kyoto’s Protocol also establish that this reduction must be carried out 
between 2008 and 2012 (period defined as the first stage for its accomplishment). In 
order to make the implementation of the emission reduction purposes possible and, at 
the same time ensure an economically viable transition for the adoption of this new 
standard, Kyoto’s Protocol established the creation of commercial mechanisms (called 
“Flexibilization Mechanisms”) to make it easy for the countries of Attachment I to 
accomplish their emission reducing goals: 
 
• Emissions Trading and Joint Implementation – instruments through which an 
industrialized country can account as their own the carbon emission reductions 
carried out in another country of Attachment I and use them for sales and 
purchase operations. 
 
• Clean Development Mechanism (CDM) – it allows countries of Attachment I to 
finance carbon emission reduction projects or purchase the volumes of emission 
reduction resulting from initiatives developed in non-industrialized countries, 
which belong to Non-Attachment I group. These countries do not have defined 
reduction goals to be accomplished during the first phase of Kyoto’s Protocol, 
which will take place between 2008 and 2012. 
 
One of the interesting aspects of Kyoto’s Protocol is that making a more rational 
and sustainable use of the resources acquires a tangible value, which is materialized in 
the quantification of the reductionin the emission of greenhouse gases. 
The quantification of avoided emissions and/or emissions that were sequestrated 
from the atmosphere (for example, tons of CO2 that were not released) makes them 
become merchandise, a new commodity. These commodities (tons of avoided or 
sequestrated CO2 emissions) will become CERs - Certified Emissions Reductions, 
which are directly traded among companies as stock placed in the market. Just like any 
other commodity, the carbon does not have a fixed price. It is subjected to offer and 
demand variations, as well as soybeans, meat or steel. 
For the companies and countries that will have to follow the emission reduction 
goals, Kyoto’s Protocol’s flexibilization mechanisms create a range of alternative 
choices for the achievement of a better cost-benefit relation of the investments that are 
necessary for the adjustment to these new standards (productive processes internal 
changes or acquisitions in the CER market generated, for example, through CDM 
projects). 
The commercialization of carbon credits is an example of the application of 
market instruments in order to improve environmental quality. This allows the 
internalization of environmental externalities originated from CO2 emissions caused by 
the use of fossil fuels and the creation of an investment fund. This fund will finance 
actions regarding the reduction of CO2 emission without affecting the economic growth 
of the developing countries. 
The creation of the instrument “Clean Development Mechanism” (CDM), its 
rules and implementation conditions are defined in Kyoto’s Protocol, Article Nº 12, 
which establishes: 
 
• CDM goal is to make it possible for the Attachment I countries to fulfill their 
emission reduction commitments, which were already quantified, and at the 
 160
same time, make it possible for the less industrialized countries (Non-
Attachment I) to achieve a sustainable development; 
• Non-Attachment I countries developing CDM projects for the reduction in 
quantified and certified emissions will be able to trade these emissions with 
Attachment I countries, which will compensate them in relation to the emissions 
they will have to reduce; 
• Clean Development Mechanism projects (CDM) and the purchase of Certified 
Emission Reductions (CERs) may involve private or public entities. 
 
The Costs of Reduction 
 
Studies carried out by University of Colorado and by the Executive Office of the 
United States Presidency, taking basically the North-American conditions into account, 
estimate a cost ranging between US$ 100 and US$ 200 for each ton of CO2 reduced by 
means of internal actions. Calculations carried out by the same institution in 1999 show 
that these costs can be reduced by 50% or even more if the reduction projects that are 
able to use the flexibilization mechanisms of Kyoto Protocol free and widely. 
In general, for the Attachment I countries, the modeling that was carried out 
indicates that using a variety of mechanisms it is possible to achieve a cost that ranges 
from US$ 10 to US$ 60 per ton of CO2. 
Regarding Latin America specifically, studies carried out by CEPAL – which 
voluntarily adopts a conservative attitude for its calculation basis – indicate that it is 
also possible to work with the same range, US$ 10 to US$ 60 for the compensation of 
tons of reduced CO2 in CDM projects in the region. According to the same estimates the 
cost for projects associated with the carbon sequestration in activities of the forest sector 
would be US$10 and US$ 20, and US$ 40 and US$ 60 for projects in the energy sector. 
Out of the total estimated amount of carbon reduction - 500 to 1000 million tons 
of equivalent carbon, within a more conservative scenario, or 600 to 1300 million tons 
of equivalent carbon according to most of the studies, it is possible to estimate that a 
volume ranging between 400 and 900 million tons of equivalent carbon must be reduced 
by using flexibilization mechanisms during the first period of the Protocol 
accomplishment, 2008 – 2012. 
A CEPAL’s conservative perspective estimates that out of the total amount of 
reductions, between 8% and 12% may be carried out in Latin America (Figure 7.11). 
 
 
Figure 7.11. CDM market estimative (Latin America position) (Ocampo,2001) 
 
 161
The projection that between 8% and 12% of the investments in CDM will be 
channeled to Latin America makes it reasonable to estimate that something about 100 
million tons of equivalent carbon or reductions of 3,670 billion tons of CO2 will be the 
object of CDM projects in the regions within the period 2008 - 2012. 
 
Brazil presents a huge potential for energy conservation. In addition to its large 
territory and abundance of natural resources, the country relies on advanced technology 
and credibility in the international market, which is a very positive scenario for CDM 
projects. 
Using data from CEPAL and from the World Bank for Latin America (where 
Brazil is highlighted), and based on a scenario regarding the international trade of 
greenhouse gases, the estimates of volumes (expressed in million tons of equivalent 
carbon) and values (expressed in million dollars) are shown in Table 7.14. 
 
Table 7.14. Estimates of CDM market volumes (Latin America and Brazil) 
(Acquatella, 2001) 
 Latin America 
Volumes 
(106 tC) 
Brazil 
Volume 
(106 tC) 
Latin America 
Value 
(106 US$) 
Brazil 
Value 
(106 US$) 
Low Level of 
Implementation 
31 1 400 10 
Medium Level of 
Implementation 
55 6 2,000 300 
Expected Level of 
Implementation 
103 22 3,400 890 
 
Presently, several Brazilian companies are convinced of the profitable potential 
of Clean Development Mechanisms. For example, the forestry company Plantar has 
already gotten resources using CERs - Certified Carbon Reductions as a guarantee. It 
sold 1.5 million tons of carbon (MtC) to the Interamerican Development Band – for 
US$ 5 the ton. The project forecasts 12 Mt of avoided carbon emissions within a period 
of 21 years. Using CDM resources, Germany will finance the production of 110 
thousand cars running with alcohol in Brazil (Época, 2002). Electricity generation 
through cane bagasse is allowing the certification of the sugar and alcohol mills to sell 
carbon credits. The mills Vale do Rosário, Alta Mogiana, Santa Elisa and Moema 
located in the state of São Paulo were certified and more than ten plants were expected 
to concluded the process in by the end of 2002. Presently, US$ 5.0 is paid for ton of 
CO2 that is not emitted. This amount can represent about 10% of the mill’s profit 
(AE,2002) 
In order to attract a significant volume of investments for national CDM projects 
and offer competitive cost for the ton of CO2 via CERs, it is important to present 
reduced risks and the assurance that the invested capital will return. 
A case study, which was carried out for a 10 MW thermal plant using eucalyptus 
as fuel, shows the possibility of attaining an additional income through the sale of 
Carbon Credits resulting in a significant reduction in the generated energy cost (Figure 
7.12). This makes projects in bioenergy much more attractive economic and 
environmentally speaking. 
 
 162
 
Figure 7.12. Variation of the electricity generation cost with and without the inclusion 
of CERs (Carpio et al. ,2002) 
 
 
 
 References 
 
ACQUATELLA, J., Oportunidades para a América Latina y el Caribe dentro Del 
Mercado del Carbono - División Medio Ambiente, CEPAL UNTAD Policy 
Fórum 30-31 agosto, Rio de Janeiro, Brasil. 2001 
 
AE - Agência Estado, “Usinas de álcool podem comercializar créditos de carbono”, 
obtido através do EFEI Energy News, 20 de agosto, 2002. 
 
BATTACHARYA, SC., ABDUL SALAM, P., SHARMA, M., “Emissions from 
biomass energy use in some selected Asian Countries”,Energia, vol. 25, pp. 169-
188, 2000. 
 
CARPIO. R. C., TEIXEIRA, F. N., LORA, E. S., Geração de energia elétrica em 
pequena escala utilizando ciclos a vapor e lenha como combustível - 4o Encontro 
de Energia no Meio Rural - Agrener 2002 - Anais em CD-ROM, UNICAMP, 
2002. 
 
CIPMA, “Fuentes e usos de energia en el sector rural pobre de Chile: síntesis de ocho 
estudios de caso”, in Energía e Desarrollo, Fund.Bariloche/Ed.de la Patagonia, 
Bariloche, 1985. 
 
EPA, “Compilation of air pollutant emission factors”, 1995. 
Época, “Alcool Alemão”, Revista Época, pág. 9, 15 de julho de 2002. 
 
 163
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. 
 
FCCC, Framework Convention of Climate Change, Kyoto Protocol, United Nations, 
Kyoto, 1997. 
HEKTOR, B., 1992, 1996 revised: Employment effects of biofuels (in Swedish), 
SIMS, Uppsala, apud FAO, 1996. 
 
IPCC, Intergovernmental Panel in Climate Change, Technologies, Policies and 
Measures for Mitigating Climate Change, (by Watson, R.T.; Marufu, C., 
Zinyowera, M.C.; Richard H. Moss), IPCC Working Group II, November 1996. 
 
MEDEIROS, J.X., Energía Renovável na Siderurgia: Análise Sócio-Econômica e 
Ambiental da Produção de Carvão Vegetal para os alto fornos de Minas 
Gerais, Tese de Doutorado, Faculdade de Engenharia de Campinas, UNICAMP, 
1995. 
 
NOGUEIRA, L.A.H.; WALTER,A.C.S., “Experiências de Geração de Energía Elétrica 
a Partir de Biomassa no Brasil: aspectos técnicos e econômicos”, Reunión 
Regional sobre Generación de Electricidad a partir de Biomasa, FAO/UNDP, 
Montevideo, 1995. 
 
OPENSHAW, K., “Estimating biomass supply: focus on Africa”, Workshop on 
Biomass Energy: Data, Analysis and Trends, International Energy Agency, 
Paris, March 1998. 
SUYOTO, MOCHTAR,M., “The performance of wet and dry dust collector”, 
Proceedings of the XXIth ISSCT Congress, 1995. 
 
WHITTAKER, R.H; MARKS, P.L., “Methods of assessing Terrestrial Productivity”, in 
Primary Productivity of Biosphere, Ed. Leith,H.; Whittaker, R.H., Springer-
Verlag, New York, 1975. 
 
 
 164
Here, there are some Internet sites that deal with bioenergy 
 
A Global Overview on Renewable Energy Sources / European Economic Community’s 
page about renewable energy. 
http://www.agores.org 
 
Aberdeen University, Department of Agriculture and Forestry. 
http://www.abdn.ac.uk/agfor/research/free/index.php
 
American Bioenergy Association / General information about bioenergy. 
http://www.biomass.org 
 
ARBRE Project / Pilot project on biomass gasification, Great Britain. 
http://www.arbre.co.uk/ 
 
British Biogen / General information about projects in Great Britain 
http://www.britishbiogen.co.uk 
 
Aston University / Page providing information about research on biomass pyrolysis 
http://www.ceac.aston.ac.uk/_ceac.htm 
 
Ben Wiens Energy Science / Fuel Cells – description and analysis. 
http://www.benwiens.com/energy4.html
 
BIOBIB - A Database for biofuels – University of Technology, Vienna / Base de dados 
com a composição elementar e aproximada, e outras características de diferentes tipos 
de biomassa. 
http://www.vt.tuwien.ac.at/biobib/biobib.html 
 
Bioenergy Association of New Zealand. 
http://www.bioenergy.org.nz/bioenergyInfo.html 
 
Biomass & Bioenergy / Monthly magazine about bioenergy. 
http://www.elsevier.nl/locate/biombioe 
 
Biomass Briquetting: Technology and Practices- 48pp REWP Report. 
http://www.rwedp.org/acrobat/fd46.pdf
 
Biomass Energy Research Association. 
http://www.bera1.org/about.html 
 
Biomass Technology Group / Bioenergy consultants. 
http://www.btgworld.com 
 
Canadian Renewable Fuel Association / Information about the perspectives of using 
ethanol and biodiesel in Canada, technologies and cost. 
http://www.greenfuels.org 
 
Catholic University of Louvain - Biomass Energy Group / Belgium. 
 165
http://www.meca.ucl.ac.be/term/geb 
 
CEEE- Centro de Estúdios de Eficiencia Energética – Universidad de Oriente, Santiago 
de Cuba, Cuba / Biomass combustion, gasification and pyrolysis. 
http://www.uo.edu.cu 
 
CENBIO -Centro Nacional de Referência de Biomassa – Universidade de São Paulo 
(USP) / Publications about economic, technical and environmental aspects of biomass 
use in Brazil. 
http://www.cenbio.org.br 
 
Center for Renewable Energy and Sustainable Development - CREST / Information and 
articles about bioenergy, links. 
http://www.crest.org/bioenergy/index.html 
 
Chemical Engineering Department - Royal Institute of Technology / Site about research 
on renewable energy. 
http://www.ket.kth.se/index_e.htm 
 
Dannish Center for Biomass Technology / The publication “Wood for Energy 
Production - Technology - Environment – Economy” is available for download. 
http://www.videncenter.dk/uk/index.htm 
 
Delft University, Netherlands / Research on biomass gasification and other bioenergy 
topics. 
http://www.ocp.tudelft.nl/ev 
 
Department of Energy - USA / Page about biomass. 
http://bioenergy.ornl.gov 
 
ENAMORA gasifier. 
http://www.energiaverde.com
 
Energy Research Center of the Netherlands- ECN Biomass / Research articles and 
reports to be downloaded. 
http://www.ecn.nl/biomass/main.html
 
ETH Zurich – LTNT - Bioenergy Research Group, Switzerland / Information about 
projects of biomass combustion and gasification and their environmental impacts. 
http://www.ltnt.ethz.ch/ltnt.html 
 
FAO Forestry Department's program on wood energy / Newsletter “Forest Energy 
Forum” and other publications. 
http://www.fao.org/forestry/FOP/FOPH/ENERGY/cont-e.stm
 
Eucalyptus forests in Brazil. 
http://bioenergy.ornl.gov/reports/euc-braz/toc.html 
 
 166
Graz University of Technology – Institute of Chemical Apparatus Design, Particle 
Technology and Combustion and Institute of Thermal Engineering / Bioenergy, 
gasification, corrosion and particle emission in biomass steam boilers and gasifiers. 
http://www.TUGraz.at/ 
 
General biomass company/ Links with photos and publications about biomass. 
http://www.generalbiomass.com/ 
 
Great Lakes Regional Biomass Energy Program / Publications about biomass 
combustion, RSU treatment, methane production and other themes related to bioenergy. 
http://www.cglg.org/projects/biomass 
 
Indian Institute of Science, Bangalore, India - Combustion Gasification & Propulsion 
Laboratory / Projects of biomass gasification 
http://cgpl.iisc.ernet.in/~cgplhome 
 
Instituto Nacional de Eficiência Energética – Brazil / Reports about cogeneration in the 
cane sugar industry. 
http://www.inee.org.br/down_loads/forum/cogerac_cana.pdf
 
International Energy Agency / Bioenergy, access to the journal “Bioenergy News” and 
other publications. 
http://www.ieabioenergy.com 
 
ITEBE - Institut Technique Europeen du Bois Energie. 
http://www.itebe.org 
 
Joanneum Research - Austria / Publications about Stirling Engines, boilers, carbon 
credits, etc. 
http://www.joanneum.ac.at/ief 
 
Michigan Biomass Energy Program / Articles about bioenergy to be downloaded. 
http://michiganbioenergy.org 
 
National Biodiesel Board / Official page 
http://www.biodiesel.org 
 
National renewable Energy Laboratory / Publications and photos about bioenergy 
http://www.nrel.gov/bioenergy.html 
 
Northern Research and Engineering Corporation – Microturbine projects 
http://www.nrec.com 
 
Natural Resources Canada/ Publications about biomass 
http://132.156.62.20/ang/identification.php 
 
NEST – Núcleo de Estudos em Sistemas Térmicos – Universidade Federal de Itajubá / 
Biomass combustion and gasification experimental studies and process modeling. 
Applications with gas microturbines, Stirling engines and fuel cells 
 167
http://www.nest.unifei.edu.brNortheast Regional Biomass Program / Technical reports about different technologies 
for the energetic use of biomass 
http://www.nrbp.org/publica.htm 
 
Ohio Biomass Energy Program /Information about technologies for the attainment of 
biogas out of animal waste and energy plantations/crops 
http://www.puc.state.oh.us/ohioutil/BioMass/biomass.html 
 
Phyllis database / Data bank providing information about the chemical composition of 
different kinds of biomass and residue 
http://www.ecn.nl/phyllis/default.html
 
Prime Energy / Manufacturer of gasifiers for rice husks 
http://www.primenergy.com 
 
PyNe - The Biomass Pyrolysis Network / Global net of researches about biomass fast 
pyrolysis 
http://www.pyne.co.uk/over.htm 
 
Regional Wood Energy Development Programme in Asia / articles and reports about 
bioenergy available for download 
http://www.rwedp.org 
 
Short Rotation Woody Group / Newsletters e articles about low rotation energy forests 
http://www.woodycrops.org 
 
Stuttgart University, Germany – Biomass Information Center 
http://www.biomasse-info.net/Englisch/index2%20englisch.htm 
 
Sustainable Minnesota's Biomass Information Page / Information about biogas, the use 
of poultry litter and cogeneration. Long list of links. 
http://www.me3.org/issues/biomass 
 
Tar Web.net - Guideline for Standardized Tar and Particle Measurement / Information 
about methods of measuring tar and particulates in the gasification gas 
http://www.tarweb.net 
 
Technical University of Denmark - Biomass Gasification Group (BGG) - Department of 
Mechanical Engineering. 
http://www.et.dtu.dk/Halmfortet 
 
TPS / Manufacturer of biomass gasifiers 
http://www.bioenergyinternational.com 
 
Twente University - Laboratory of Thermal Engineering / Biomass pyrolysis and 
gasification 
http://www.thw.wb.utwente.nl 
 168
 
Universidad de Zaragoza - Departamento de Ingenieria Quimica y 
Tecnologias del Medio Ambiente / Thermochemical treatment of residues: pyrolysis, 
gasifications and combustion 
http://wzar.unizar.es/acad/fac/cps/iq 
 
University of Southern Denmark - Bioenergy Department / Information and reports 
about biogas 
http://websrv5.sdu.dk/bio 
 
University of Flensburg - ARTES Institute - Biomass Gasification: Technology and 
Utilization / Information about biomass gasification in a very comprehensive way. 
http://mitglied.lycos.de/cturare/bio.htm 
 
Utrecht University, Netherlands - Research cluster on Biomass and Waste / Information 
about projects and articles about bioenergy, gasification, cogeneration, gas turbines, 
methanol 
http://www.chem.uu.nl/nws/www/nws.html 
 
Vermont Project / Pilot project on biomass gasification 
http://www.burlingtonelectric.com/SpecialTopics/Gasifier.htm 
 
VTT Research Institute - Finland / Publications about biomass conversion technologies 
http://www.vtt.fi/ene/results 
 
Wood Gas - The Biomass Energy Foundation / Information about biomass gasification 
and stoves 
http://www.woodgas.com 
 
	A. Environmental effects during the agricultural phase
	B. Environmental effects during the conversion phase
	B. Sequestration and replacement of carbon emissions
	Rotation
	AAI*
	Scenario
	C. Carbon credit market and the clean development mechanism 
	TOTAL
	Natural Resources Canada/ Publications about biomass
	http://132.156.62.20/ang/identification.php
	Northeast Regional Biomass Program / Technical reports about
	http://www.nrbp.org/publica.htm
	Ohio Biomass Energy Program /Information about technologies 
	http://www.puc.state.oh.us/ohioutil/BioMass/biomass.html
	Regional Wood Energy Development Programme in Asia / article
	http://www.rwedp.org