briquette material assessment

2012

TechnoServe Guatemala Boston Nyer

------------------

University of Colorado

Engineering for Developing

Communities Program

[FUEL BRIQUETTE MATERIALS ASSESSSMENT ] This document details the procedures and findings from the spring 2012 trip of Boston Nyer, from the University of Colorado, to Guatemala in collaboration with TechnoServe. The objective of the trip was to determine the feasibility of fuel briquettes from various agricultural waste streams in the Chiquimula department of Guatemala.

FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012

Contents Executive Summary ....................................................................................................................................... 3

Introduction to Briquettes ............................................................................................................................. 4

Supply of Material ......................................................................................................................................... 5

Physical Integrity Test ................................................................................................................................... 8

Burn Test ....................................................................................................................................................... 9

Business Opportunities with Waste Materials ............................................................................................ 13

References ................................................................................................................................................... 14

Appendix ..................................................................................................................................................... 15


Executive Summary Biomass briquettes can be used as a fuel to displace firewood, charcoal, or other solid fuels. In the proper context fuel briquettes can: save time, save money, decrease local deforestation rates, and provide and income generating opportunity. The goal of this investigation is to determine the feasibility of briquettes from a variety of raw materials, primarily coffee wastes and sawdust which were identified by TechnoServe Guatemala in the Preliminary Market Study of Organic Fertilizer and Firewood (Charcoal). Other materials evaluated are: paper, cardboard, cow dung, banana peels, corn husks and charcoal fines. Paper, banana peels and charcoal fines are ruled out for supply limitations. Each binding material was tested with each filler to determine combinations that could physically make a briquette (Physical Integrity Test). Successful permutations progressed to the burn test to determine if they could be combusted in, and make tortillas on, locally available stoves. Although all briquettes were able to burn in a simple partial gasifier stove, only one briquette permutation burned in a locally available stove, paper and sawdust. It is suspected that cardboard and sawdust can behave similarly, although results different in this investigation. Basic market research tells us that 200-300lbs. of cardboard is available each month for $0.18 per 100lbs. at the dump. Roughly 1,545lbs. of sawdust is available each month for $0.017 per lb. This presents a niche market for fuel briquettes. Looking beyond fuel briquettes, coffee pulps are the most interesting waste material assessed. At one of 26 coffee processing facilities in Chiquimula, there are 10 12 small dump trucks of waste produced daily. The waste stream is completely unutilized and is an environmental and public health hazard. The material should be strongly considered for organic fertilizer, power generation, or other productive outlets.


Introduction to Briquettes Fuel briquettes are a compressed block of organic waste materials used for cooking and/or heating.

They are often used as a development intervention to replace firewood, charcoal, or other solid fuels. In

the proper context fuel briquettes can save time, save money, decrease local deforestation rates, and

provide and income generating opportunity.

Several fuel briquetting programs have been successfully

demonstrated around the world. In theory, fuel briquettes can be

made of any organic material, and because of this, most fuel

briquetting programs use distinct composition recipes for their

briquettes. Because of both the technologys young age and the

wide variety of recipes used, there is no formula to determine a

viable fuel briquette recipe. Therefore each new program must

conduct comprehensive tests to find the appropriate recipe for the

situation.

Briquettes are held together by a binding agent or binder. This

binding material can be any fibrous organic material. The material

must be processed in order to hold the briquette together often

through partial decomposition. The binder can either be used by

itself or mixed with a filler. The filler should be locally available,

widely available, and improve the combusting performance of the

briquette. For example in an urban setting, if decomposed corn

husks are used as a binder then saw dust could be used as a filler to

produce a more combustible briquette.

A set of three tests are used to determine if a briquette has

sufficient structural integrity to hold together (The Legacy

Foundation 2003): The Squeeze Test, Expansion Test, and Shake

Test.

Figure 1: Squeeze Test

Figure 2: Expansion Test

Figure 3: Shake Test


Supply of Material The majority of materials assessed were identified ahead of the trip based on market data collected by

TechnoServe Guatemala and other research. Other materials were added as appropriate. The materials

that were analyzed were split into two groups, binders and fillers. The binders were: paper, cardboard,

dung, corn husk and banana peels. The fillers were: sawdust, coffee husks and charcoal fines.

Identification of appropriate waste materials is fundamental for the success of a fuel

briquetting program. Cost to the end-user is a driver of the feasibility of the product. The

waste materials need to be reliably and cheaply available throughout the year in large

quantities. It is imperative to understand the full lifecycle of a material before it is used in a

fuel briquetting program. All of the uses, locations, quantities, stakeholders, and values must

be thoroughly understood. Each material is described in more detail below Table 1.

Table 1 provides an overview of the materials assessed through this project. The last column

identifies whether the waste material will be considered in this initial study (Y), will not considered

at all (N), or should be considered in the future (F). Each material is described in more detail below

Table 1.

Table 1: Overview of waste materials available in Chiquimula District

Raw Waste Material

Quantity Available [H/M/L]

Frequency of Availability

Location Other Uses

Feasible supply [Y/N/F]

Bin

de

rs

Paper L Variable Disperse Multiple N

Cardboard M Continuous Dump Recycled Y

Cow Dung

H Continuous Disperse Fertilizer Y

Banana Peel

L Continuous Disperse in Chiquimula. Concentrated in other regions.

None N, other regions

Corn Husk

H Continuous Ubiquitous Feed for animals

Y

Fille

rs

Coffee Pulps H Continuous Coffee processing facilities

None, waste

Y

Coffee Husk

L October March

Coffee processing facilities

Coffee nurseries

Y

Wood Shavings & Saw Dust

M Continuous Wood mills Various, sold

Y

Charcoal fines L Continuous Charcoal vendors

Sold for fuel

N


Paper

Waste paper is not available in any meaningful quantity in the Chiquimula Department of Guatemala.

This material was used as a benchmark for analysis as paper is extremely common in fuel briquetting

initiatives globally.

Cardboard

At the dump in Chiquimula, cardboard is collected to be sold into the recycling business. 200 -300lbs. of

cardboard are recovered each month and sold for $0.18 per 100lbs.

Cow dung

Cow dung is ubiquitous and can be used as a binder for briquettes. The material is often used as

fertilizer for farms or unutilized. It can be sourced for the cost of collection.

Corn Husk

Corn husks are ubiquitous and can be used as a binder or filler for briquettes. Although the material has

other uses, such as animal feed, the vast majority is unutilized. Therefore, the material can be sourced

for the cost of collection.

Banana Peels Banana peels contain many fibers ideal for binding a briquette together. Fuel briquettes from banana

peels can be a value add to the Technoserve Guatemala organic banana program. Although the

material should not be considered for use in Chiquimula, it may add value to a banana program in

other regions of the country.


Sawdust

Sawdust is created at the 3-4 sawmills in the department of Chiquimula (Palacios, 2011). The largest

sawmill produces 120lbs. of sawdust and 1,120lbs. of woodchips per week. Each 40lb. sack of sawdust

is sold for Q5 and Q3 for woodchips (approximately $0.017 & 0.01/lb).

Coffee Husks

Although coffee is grown in several high altitude communities in Chiquimula, such as Tachoche, the

husks are only available at coffee processing sites. There are approximately 26 coffee mills in the

Chiquimula department based upon the Market Analysis conducted by TechnoServe Guatemala

(Palacios, 2011). These facilities sell a combination of green coffee and beans with the husk still on the

bean. One facility surveyed produced approximately 10-12 40lb sacks per week for Q15 each

(approximately $2.00). The husks are used in coffee nurseries and for other purposes. The coffee husk

waste stream exists, but much smaller than coffee pulps.

Coffee pulps

10 small dump trucks or approximately 60 tons of coffee pulps are produced daily at one of the 26

coffee production facilities in the department of Chiquimula. The material is dumped on the periphery

of the facility and unused and is toxic to the local environment, particularly the ground water. The

material is available for the cost of transportation.

Charcoal fines

Charcoal fines and dust are inherently created from the handling of charcoal. Approximately 2,000

45lb. sacks of fines are sold in the market each week for Q40 each (approximately $5.30). The high

cost demands a strong value add for the material to be considered for incorporation into the product.


Physical Integrity Test Organic waste materials available in Tachoche and low-production screw briquette press from CU

Boulder were used to create various permutations of briquettes. Each binder and filler was combined

with and without the addition of charcoal fines (in attempts to assist in combustion). Table 2 provides

an overview of the successful and unsuccessful combinations of materials. These permutations are

shown by ratio of volumes and weights per liter are shown in the Appendix. The success is determined

by the squeeze test, expansion test, and a shake test as defined by The Legacy Foundation (see

Introduction to Briquettes). Failure (X) was determined if the briquette could not pass the three tests

at a minimum ratio of 1:1 of filler to binder. Additionally, the procedure for processing each material is

shown in the Appendix.

Table 2: Permutations of physical integrity testing of briquettes

Binders

Material Paper (volume : volume)

Cardboard (volume : volume)

Dung (volume : volume)

Corn Husks (volume : volume)

Banana Peel (volume : volume)

Fille

rs

Sawdust (volume : volume)

3:1 (S:P)

3:1 (S:Ca)

X X 3:1

(S:B)

Sawdust + Charcoal (volume : volume)

16:8:9 (S:Ch:P)

16:8:9 (S:Ch:Ca)

X X 16:8:9

(S:Ch:B)

Coffee Husks (volume : volume)

3:1 (C:P)

1:1 (C:Ca)

X X X

Coffee Husks + Charcoal (volume : volume)

2:1:1 (C:Ch:P)

2:1:1 (C:Ch:Ca)

X X X

Misc. permutation 2Cofee:1Banana:1Corn

As shown in Table 2, paper, cardboard and banana peels were the most successful binders. The addition of charcoal fines generally detracted from the physical ability of the briquette to hold together. Corn husks and cow dung were not successful as a binder during this field campaign. It should be stressed that cow dung and corn husks can be successful binding materials, but were not with the present materials and processing techniques (see the Appendix for details). Empirical evidence shows that corn husks are most successful when partially decomposed, however the material has a slow decomposition process. This decomposition period drastically increases the production Takt time, which requires increased resources (cash, space, labor, etc.). During this project, the corn husks were charred in attempt to release the fibers, but this ruined the structural integrity of the material. Unfortunately, coffee pulps were not evaluated as a filler due to a lack of processing options for the material. There are various material processing options that exist in practice, such as a hammer mill or the Easy BioGrind from Engineers Without Borders Cincinnati Professional Chapter.


Burn Test

Stoves

Core burn tests were completed on an ONIL improved stove (Figure 4) and a comal conventional stove

(Figure 4). The comal conventional stove is essentially an open fire with a round ceramic cooking

surface placed on top of supports of rock, blocks or concrete. The ONIL stove represents the highest

performing biomass stove currently available in Guatemala. The stove uses rocket stove principles along

with a plancha and chimney.

Lastly, every briquette was tested in a partial gasifier stove for validation purposes (Figure 6). The

partial gasifier is made from two 1 gallon paint cans. The bottom can has 11 holes in the bottom for

primary air. The can was raised 1 off the ground. Secondary air was supplied to the fire through 12

holes surrounding the circumference of the top can sitting directly on top of the first.

Figure 4: El Comal Conventional Figure 5: ONIL Improved Stove

Figure 6: Partial Gasifier Stove


Lighting and Loading

5 to 6 briquettes were used in each trial. In the comal, the briquettes were piled together with the fire-

starter in the middle (Figure 7). In the ONIL, 4 or 5 briquettes were piled vertically in the combustion

chamber and one was placed vertically in the feed chamber similarly to the Rok Briquette Stove (Figure

9 & Figure 8). As per local customs, Jocote, or sap impregnated wood, was used for starting the fire.

Approximately 5 pieces of 5 grams of fire-starter were used during lighting.

Figure 9: Vertically Oriented Briquettes in ONIL with Jocote Figure 8: Fuel Briquette in Feed Chamber of ONIL Stove

Figure 7: Fuel Briquettes in Comal


Results

The results of the burn tests are outlined in Table 3. No briquettes were able to sustain a fire within the

comal conventional stove. Each permutation run in the comal filled the kitchen with smoke.

None of the briquettes with a banana binder were able to combust in either the comal or ONIL. The

briquettes with coffee husks as a filler were also unable to perform in either available stove.

The paper+sawdust briquette was the only permutation that was able to complete a representative

cooking event cook tortillas to the satisfaction of the cook. Interestingly, the paper+sawdust+

charcoal briquette was not able to cook tortillas properly. Moreover, the moisture content of the

paper+sawdust was almost double that of the paper+sawdust+charcoal at 22.2% as compared to 11.5%

(Table 5 in the Appendix). However, it should be noted that the paper+sawdust started with 6

briquettes compared to 5.

Table 3: Results of Burn Tests in Comal and ONIL

Binders

Material Paper (# of briq.)

Cardboard (# of briq.)

Dung (# of briq.)

Corn Husks (# of briq.)

Banana Peel (# of briq.)

Fille

rs

Sawdust

ONIL (6): Lit immediately; made tortillas quickly; family

satisfied

ONIL (5): Slow to light, cooked

tortillas but too slowly

X X ONIL (6): burned;

not enough power to make tortillas

Sawdust + Charcoal

ONIL (5): Lit slowly; made

tortillas slowly N/A X X

ONIL (6): charred; smoldered; could not make tortillas

Coffee Husks

Comal (5): smoldered and

went out; lots of smoke

N/A X X X

Coffee Husks + Charcoal

Comal (5): smoldered and

went out; lots of smoke

ONIL (5): smoldered,

charred and went out

X X X

Misc. permutation Cofee:Banana:Corn ONIL: Could not light

Each permutation of briquettes was placed into the partial gasifier to determine if they could combust in

a tailored environment. Every briquette burned with ease in this stove.


Briquettes and Stoves

It has been demonstrated that an appropriate combustion environment is fundamental for

briquettes to be burned successfully. Without an optimized combustion environment

briquettes will not function properly. The briquettes able to ignite and sustain a flame are likely

to produce an overwhelming amount of smoke, similar to how wood responds to a 3-stone fire

environment. Stoves and fuels must be addressed together. The smoke in Figure 10 and clean

burning in Figure 11 demonstrate this lesson. Further evidence was provided as smoke was

generated when the top paint can was removed from the partial gasifier. The smoke

immediately turned into a flame when the top can was replaced.

Figure 10: Smokey Fire in a Comal Figure 11: No Smoke in Partial Gasifier


Business Opportunities with Waste Materials

1. Of the materials that are viable from a supply perspective, there are only two that are viable

from a technical standpoint (passed the Physical Integrity and Burn Tests): cardboard and

sawdust. Both of these materials are cheaply and consistently available at substantial quantities

around Chiquimula. Furthermore these two materials are among the easiest and fastest to

procure and process. However, this is a niche market only with a ceiling of approximately

1200lbs. per month.

Note: the glue must be removed from cardboard before combustion for health purposes.

2. Fuel briquettes aside, coffee pulps are the most interesting waste stream in Chiquimula. This

represents the largest, centrally located waste stream in the department and it is currently

unutilized. Furthermore it is an environmental and public health hazard as of present. There

are two opportunities that have been identified with this waste material: organic fertilizers and

power generation. Both options should be deeply considered.


References Palacios, M. (2011). Preliminary Market Study of Organic Fertilizer and Firewood (Charcoal) in

Guatemala; with Emphasis on the Region of Chiquimula. Guatemala City, Guatemala:

TechnoServe Guatemala.

The Legacy Foundation. (2003). Fuel Briquette Making: A User's Manual. Oregon.


Appendix

Weights per liter of each wet processed material

Table 4: Wet weight processed materials

Material Wet weight per liter (kg)

Paper 1.21

Cardboard 1.36

Banana 1.37

Dung 1.185

Corn husk 0.46

Sawdust 0.2

Coffee husk 0.33

Charcoal fines 0.63

Material Processing

Paper & Cardboard: Paper and cardboard were both soaked in water until it was turned into a pulp.

Cow dung: Cow dung was put through a hand molino grinder yielding fine grinds that were soaked in

water for one day.

Corn Husk: Partially decomposed corn husks were found on local farms in the Chiquimula department.

The husks were sorted to only accept the most decomposed potion, which was then torn and soaked in

water for three days.

Banana Peels: Banana peels were put through the hand molino and the un-processed chunks were

removed. The end result was a slop.

Sawdust: N/A

Coffee Husks: The coffee husks were sifted to remove any pulps or twigs. Only the fine husks

remained. Some husks were dampened for four days, however this had a counterproductive response

during Integrity Testing.

Charcoal fines: Charcoal fines were sorted to remove larger chunks. Dust and small particles remained.

Coffee pulps: N/A


Moisture Contents and Volumes of Briquettes

A sample size of 2 briquettes was evaluated for each permutation to determine the moisture content

and density. The weight of each permutation was measured with an Edlund SR-1000c 1000g/5g analog

scale. The moisture content was determined by weighing the briquette after air drying and then at

approximately 0% moisture content. The briquettes were dried in a Sharp 1000W/R-21LV microwave

for 3:00 or until the weight stopped reducing with increased time. A sample of the

cardboard+sawdust+charcoal briquettes was not recorded through human error.

Table 5: Moisture Content and Density of Briquettes

Composition Weight (g)

Dry Weight (g)

Moisture Content

(%)

Volume (cc)

Dry Density (g/cc)

Paper+ Sawdust 180 140 22.2% 311 0.225

Paper+ Sawdust+ Charcoal

260 230 11.5% 389 0.296

Paper+ Coffee Husks

240 195 18.75% 369 0.264

Paper+ Coffee Husks+ Charcoal

305 240 21.3% 428 0.281

Cardboard+ Sawdust

137 83 39.4% 389 0.213

Cardboard+ Sawdust+ Charcoal

N/A N/A N/A N/A N/A

Cardboard+ Coffee Husks

690 570 17.4% 467 0.204

Cardboard+ Coffee Husks+ Charcoal

152 120 21.1% 389 0.154

Banana+ Sawdust

265 175 33.9% 350 0.250

Banana+ Sawdust+ Charcoal

310 220 29% 369 0.298

briquette material assessment

Documents

feasibility of fuel

waste materials

feasibility of briquettes

proper context fuel

briquette permutation

charcoal fines

briquette physical integrity

firewood charcoal