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2012
TechnoServe Guatemala Boston Nyer
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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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
Contents Executive Summary
.......................................................................................................................................
3
Introduction to Briquettes
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4
Supply of Material
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5
Physical Integrity Test
...................................................................................................................................
8
Burn Test
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9
Business Opportunities with Waste Materials
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13
References
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14
Appendix
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15
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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.
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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
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FUEL BRIQUETTE MATERIALS ASSESSSMENT March 25, 2012
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