**3.1 Energy analysis**

The experiment was based on the preparation of various briquette prototypes, considering size, shape, and composition as relevant characteristics for each type, to obtain the greatest energy efficiency—that is to say, a similarity in heating capacity and combustion efficiency.

**Table 2** shows that the best briquette prototype is 1, which is referred to as "BR 1," with a heating capacity of 4040 kcal/kg and a combustion efficiency of 80.39%. This briquette is composed of 80% rice husk and 20% cassava starch. Other ingredients are not suitable for making briquettes, such as rubber which increases humidity or bentonite which results in low compaction levels. **Table 2** also shows the physical-chemical characteristics of each briquette prototype, represented by the nomenclature "BR."

Within the results presented in **Table 2**, density is the physical-chemical characteristic relevant to briquette production methods, due to the type of machine used for compaction. For this experimental process, in which a hydraulic press was used, density was greater than that of a briquette machine, due to the greater compression force that machines have (an average theoretical value of 350 kg/m3 , based on statistical data regarding the impact between compression capacity and this type of material) [25]. The results obtained in Ref. [26] showed a very low value of the density. Adding a binder increases moisture content, reducing combustion efficiency, since it is proportional to the increase in density. In addition, they mention an important aspect regarding rice husk transport costs, stating that this cost will be higher due to reduced availability [26].

Agglutinants should be added to artisanal briquettes to better compact the husk and cassava starch mixture. In addition, the cost of transporting the briquettes is always nominal. For the present case, briquette density was 678.7 kg/m3 .

As well as comparing heating capacity between different briquette prototypes, it will be necessary to compare the physical-chemical properties with those of firewood, to determine the advantages of using briquettes. In **Table 3**, a greater heating capacity is observed compared to firewood, since firewood loses a large part of heat energy due to certain properties. Briquettes, however, burn their initial

**121**

be needed for food preparation.

cutting down trees.

**3.2 Environmental impact analysis**

*Comparison of energy characteristics for both fuels.*

*Sustainable Energy Model for the Production of Biomass Briquettes Based on Rice Husks…*

Shape Cylindrical

**Characteristic Components BR 1 BR 2 BR 3 BR 4 BR 5 BR6** Composition Rice husk 80 90 75 90 80 80

Diameter (mm) 73 73 53 53 53 73 Height (mm) 22 28 35 30 30 37 Humidity (%) 9.63 10.97 8.23 8.23 9.46 10.86

**Characteristic Unity Rice husk briquettes Firewood** Heating power kcal/kg 4040 4010 Bulk density kg/m3 860 820 Ash % 1.50 0.92 Humidity % 9.0 17.4 Fixed carbon % 15.6 16.8 Volatile matter % 86.5 82.2 Combustion efficiency % 80.39 70.40

Yucca starch 20 0 15 10 10 0 Bentonite 0 10 5 0 10 0 Rubber 0 0 5 0 0 20

678.7 654.7 604.3 409.5 906.5 963.7

8 12 10 11 12 10

4040 4010 3745 4020 4010 3500

80.39 78.13 79.17 76.29 77.14 71.29

properties until completely consumed. The briquette has a combustion efficiency value of 80.39%, approximately 10% more than firewood, meaning less fuel would

**Figure 10** shows the briquette prototype 1, denominated "BR 1," which obtained a heating capacity value of 4040 kcal/kg and a combustion efficiency of 80.39%.

Within the energy model, environmental impact will be measured based on the CO2 reduction from the use of rice husks in briquette production, as well as gases emitted by firewood for food preparation and the amount of CO2 produced by

The first source of CO2 emissions is the number of hectares deforested due to firewood production; thus, substituting firewood with briquettes will reduce greenhouse gas emissions. The amount of firewood obtained per tree cut was calculated

*DOI: http://dx.doi.org/10.5772/intechopen.81817*

Bulk density (kg/

Time of ignition (min)

Heating power (kcal/kg)

Combustion efficiency (%)

*Briquette prototype analysis.*

m3 )

**Table 2.**

**Table 3.**


*Sustainable Energy Model for the Production of Biomass Briquettes Based on Rice Husks… DOI: http://dx.doi.org/10.5772/intechopen.81817*

#### **Table 2.**

*Green Energy Advances*

instruments.

**3. Results**

rice husk briquettes.

**3.1 Energy analysis**

ity and combustion efficiency.

the nomenclature "BR."

higher due to reduced availability [26].

of the briquette production proposal was industrial and with a business vision, it would be necessary to use a briquette machine and sophisticated measuring

combustion efficiency (%) = (initial mass − final mass)/mass bc (8)

mass bc (kg) = [mass husk × (1 − %ash)] + [mass binder × (1 − %ash)](9)

Experiment results will be analyzed in two ways. The first will be based on the energy analysis of the briquette prototypes and the comparison of their physical–chemical properties with firewood through agglomeration and granulometry methods. The second analysis corresponds to the environmental impact in lowincome agricultural areas in Peru, where firewood is used, from the production of

The experiment was based on the preparation of various briquette prototypes, considering size, shape, and composition as relevant characteristics for each type, to obtain the greatest energy efficiency—that is to say, a similarity in heating capac-

**Table 2** shows that the best briquette prototype is 1, which is referred to as "BR 1," with a heating capacity of 4040 kcal/kg and a combustion efficiency of 80.39%. This briquette is composed of 80% rice husk and 20% cassava starch. Other ingredients are not suitable for making briquettes, such as rubber which increases humidity or bentonite which results in low compaction levels. **Table 2** also shows the physical-chemical characteristics of each briquette prototype, represented by

Within the results presented in **Table 2**, density is the physical-chemical characteristic relevant to briquette production methods, due to the type of machine used for compaction. For this experimental process, in which a hydraulic press was used, density was greater than that of a briquette machine, due to the greater compres-

, based on

.

sion force that machines have (an average theoretical value of 350 kg/m3

always nominal. For the present case, briquette density was 678.7 kg/m3

statistical data regarding the impact between compression capacity and this type of material) [25]. The results obtained in Ref. [26] showed a very low value of the density. Adding a binder increases moisture content, reducing combustion efficiency, since it is proportional to the increase in density. In addition, they mention an important aspect regarding rice husk transport costs, stating that this cost will be

Agglutinants should be added to artisanal briquettes to better compact the husk and cassava starch mixture. In addition, the cost of transporting the briquettes is

As well as comparing heating capacity between different briquette prototypes, it will be necessary to compare the physical-chemical properties with those of firewood, to determine the advantages of using briquettes. In **Table 3**, a greater heating capacity is observed compared to firewood, since firewood loses a large part of heat energy due to certain properties. Briquettes, however, burn their initial

**120**

*Briquette prototype analysis.*


#### **Table 3.**

*Comparison of energy characteristics for both fuels.*

properties until completely consumed. The briquette has a combustion efficiency value of 80.39%, approximately 10% more than firewood, meaning less fuel would be needed for food preparation.

**Figure 10** shows the briquette prototype 1, denominated "BR 1," which obtained a heating capacity value of 4040 kcal/kg and a combustion efficiency of 80.39%.

#### **3.2 Environmental impact analysis**

Within the energy model, environmental impact will be measured based on the CO2 reduction from the use of rice husks in briquette production, as well as gases emitted by firewood for food preparation and the amount of CO2 produced by cutting down trees.

The first source of CO2 emissions is the number of hectares deforested due to firewood production; thus, substituting firewood with briquettes will reduce greenhouse gas emissions. The amount of firewood obtained per tree cut was calculated

**Figure 10.** *"BR 1" rice husk briquette prototype 1.*

in a study by the National University San Martín (UNSM) in Tarapoto [27]. Eq. 10 shows the volume of an average tree in the San Martín region, which is 0.32 m3 . Note that the height of the tree is denominated as "commercial H," the coefficient value for San Martín is denominated "Cf," and "AB" was calculated in Eq. 10:

$$\begin{aligned} \text{value for Sun Martin's denominators} & \text{``Cf'} \text{ and 'AB' was calculated in Eq. 10:}\\ \text{Volume (m}^3\text{)} &= \text{D}^2 \times 0.7854 \times \text{commerical H} \times \text{Cr} \\ \text{Volume (m}^3\text{)} &= 0.302 \times 0.7854 \times 7 \times 0.65 \\ \text{Volume (m}^3\text{)} &= 0.3216 \end{aligned} \tag{10}$$

On the other hand, based on the estimated volume of firewood obtained from a tree, which is 0.32 m3 , it was possible to calculate the estimated number of trees that would be deforested. Information was taken from a study by "Tienda Biomasa" of the Spanish company Leñas Oliver SL, which for the sale of its ecological products such as briquettes, pellets, and other biofuels calculated that 1000 kg of firewood is equivalent to 2m3 [28]. Therefore, if a specific briquette production proposal focuses on 23% of the market, in a population that consumes 27,600 kg of firewood monthly, the volume of firewood obtained would be 55.20 m3 . From the value obtained in Eq. 10, it was estimated that 173 trees would be saved monthly.

In the analysis of trees saved from the use of briquettes, it is important to consider the number of forest hectares that will be protected. In this case, the trees of the San Martín region belong to 50-year secondary forests, according to data extracted by the Moyobamba Forestry Office [29]. Thus, 6 fewer hectares will be deforested per year, according to characteristics in **Table 4**.

**Figure 11** shows the exponential relationship between the number of trees saved and the amount of CO2 emissions that each of them represents. From a study on the environmental impact of firewood, by Peruvian researchers Torres, H. and Polo, C., with the collaboration of scientists Seifert, D. and Neuoetting, D., it has been found that 1 kg of firewood emits 1.83 kg CO2, since half the wood's mass is carbon (C) and its relation with the molecular weight of CO2 is 44/12, thus 1 kg of firewood produces 0.5 (44/12 kg of CO2) = 1.83 kg of CO2 [30].

As mentioned above, the number of deforested hectares and CO2 emissions will depend directly on the type of market on which briquette production will focus. In this case, the monthly consumption of 23% of the population of San Hilarión is 27,600 kg of firewood, which represents monthly CO2 emissions of 50,508 kg. Therefore, 33,120 trees are estimated for a 5-year period; that is to say, the use of rice husk briquettes would reduce CO2 emissions by almost 10,000 kg.

Finally, in addition to reducing CO2 emissions by protecting trees, CO2 emissions will further be reduced with respect to burning rice husks in cultivation areas

**123**

**Figure 12.**

*Sustainable Energy Model for the Production of Biomass Briquettes Based on Rice Husks…*

or around the city, due to the fact that a considerable amount of this agricultural waste product will be recycled in briquette preparation. From a physical-chemical rice husk analysis by the research group *Gestión Ambiental Sostenible* (Sustainable Environmental Management), formed by environmental engineers Aberlardo Prada and Carol Cortés of the University of Llanos, 1 kg of carbonized rice husk is equivalent to 1.43 kg of CO2 [31]. Thus, from the number of briquettes produced, the CO2 reduction from recycling rice husks can be calculated. **Figure 12** shows the relationship between the amount of husk used to make briquettes and the reduction

**Type of forest Diameter type Trees/ha** Secondary forest (50 years) 20–30 cm 340

Over 30 cm 100

*DOI: http://dx.doi.org/10.5772/intechopen.81817*

*Characteristics of forest resources in San Martín.*

*Amount of CO2 emissions avoided by not cutting trees.*

*Amount of CO2 emissions avoided by recycling rice husks.*

in CO2 emissions.

**Table 4.**

**Figure 11.**

*Sustainable Energy Model for the Production of Biomass Briquettes Based on Rice Husks… DOI: http://dx.doi.org/10.5772/intechopen.81817*

or around the city, due to the fact that a considerable amount of this agricultural waste product will be recycled in briquette preparation. From a physical-chemical rice husk analysis by the research group *Gestión Ambiental Sostenible* (Sustainable Environmental Management), formed by environmental engineers Aberlardo Prada and Carol Cortés of the University of Llanos, 1 kg of carbonized rice husk is equivalent to 1.43 kg of CO2 [31]. Thus, from the number of briquettes produced, the CO2 reduction from recycling rice husks can be calculated. **Figure 12** shows the relationship between the amount of husk used to make briquettes and the reduction in CO2 emissions.


#### **Table 4.**

*Green Energy Advances*

**Figure 10.**

*"BR 1" rice husk briquette prototype 1.*

tree, which is 0.32 m3

is equivalent to 2m3

in a study by the National University San Martín (UNSM) in Tarapoto [27]. Eq. 10 shows the volume of an average tree in the San Martín region, which is 0.32 m3

Note that the height of the tree is denominated as "commercial H," the coefficient value for San Martín is denominated "Cf," and "AB" was calculated in Eq. 10:

Volume (m3) = D<sup>2</sup> × 0.7854 × commercial H × Cf Volume (m3) <sup>=</sup> 0.302 <sup>×</sup> 0.7854 <sup>×</sup> <sup>7</sup> <sup>×</sup> 0.65

(10)

On the other hand, based on the estimated volume of firewood obtained from a

would be deforested. Information was taken from a study by "Tienda Biomasa" of the Spanish company Leñas Oliver SL, which for the sale of its ecological products such as briquettes, pellets, and other biofuels calculated that 1000 kg of firewood

focuses on 23% of the market, in a population that consumes 27,600 kg of firewood

**Figure 11** shows the exponential relationship between the number of trees saved and the amount of CO2 emissions that each of them represents. From a study on the environmental impact of firewood, by Peruvian researchers Torres, H. and Polo, C., with the collaboration of scientists Seifert, D. and Neuoetting, D., it has been found that 1 kg of firewood emits 1.83 kg CO2, since half the wood's mass is carbon (C) and its relation with the molecular weight of CO2 is 44/12, thus 1 kg of firewood

As mentioned above, the number of deforested hectares and CO2 emissions will depend directly on the type of market on which briquette production will focus. In this case, the monthly consumption of 23% of the population of San Hilarión is 27,600 kg of firewood, which represents monthly CO2 emissions of 50,508 kg. Therefore, 33,120 trees are estimated for a 5-year period; that is to say, the use of

Finally, in addition to reducing CO2 emissions by protecting trees, CO2 emissions will further be reduced with respect to burning rice husks in cultivation areas

rice husk briquettes would reduce CO2 emissions by almost 10,000 kg.

obtained in Eq. 10, it was estimated that 173 trees would be saved monthly. In the analysis of trees saved from the use of briquettes, it is important to consider the number of forest hectares that will be protected. In this case, the trees of the San Martín region belong to 50-year secondary forests, according to data extracted by the Moyobamba Forestry Office [29]. Thus, 6 fewer hectares will be

, it was possible to calculate the estimated number of trees that

[28]. Therefore, if a specific briquette production proposal

Volume (m3) = 0.3216

monthly, the volume of firewood obtained would be 55.20 m3

deforested per year, according to characteristics in **Table 4**.

produces 0.5 (44/12 kg of CO2) = 1.83 kg of CO2 [30].

.

. From the value

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*Characteristics of forest resources in San Martín.*

**Figure 11.**

*Amount of CO2 emissions avoided by not cutting trees.*

**Figure 12.** *Amount of CO2 emissions avoided by recycling rice husks.*

In this way, social costs on the population will be minimized, since there will be fewer respiratory and pulmonary diseases due to the reduction of CO2 emissions from felling trees and burning rice husk. It was estimated that in 1 year, CO2 emissions could be reduced by 833,000 kg.
