Division of Energy Systems23747/FULLTEXT01.pdf · number of briquette production sites to study the...

Biomass Briquettes in Malawi

Olle Faxälv Olof Nyström

Division of Energy Systems

Degree Project

Department of Management and Engineering LIU-IEI-TEK-A--07/00129--SE

Minor Field Study MFS-report nr 103 ISSN 1400-3562

I

Abstract In Malawi 2.5 % of the forest disappears each year. The use of firewood and charcoal, deriving

from forest resources, accounts for about 99 % of the household energy demand in Malawi and is a

cause to the deforestation. The Government of Malawi recently launched a programme called

Promotion of Alternative Energy Sources Programme (PAESP) with the aim to reduce the use of

firewood and charcoal. One of the fuels included in the programme is the biomass briquette. The

aim with this study is to evaluate the viability of biomass briquettes as a sustainable alternative

energy source to firewood and charcoal for households in Malawi.

Research for the study was carried out during three months in Malawi. Visits were made to a

number of briquette production sites to study the manufacturing methods and to collect briquette

samples. The briquettes were tested using various methods and then compared with results for

firewood and charcoal.

At the moment various production methods are used in Malawi, with a high difference in technical

complexity and cost. Machines produced from wood using very basic mechanics can apply similar

pressure as more advanced metal pressers. They also seem to be better suited than those made of

metal, in terms of price and availability.

The majority of the briquette producers in Malawi use waste paper as base material. Although the

paper briquettes are good, other raw materials will be needed if the production is supposed to be

significantly increased.

The briquettes burn well using the most common stoves in Malawi, including the commonly used

charcoal stove. While firewood is cheaper to use than other available fuels, the briquettes seem to

be able to compete with the fuel costs for charcoal.

III

Sammanfattning I Malawi försvinner 2.5 % av skogen varje år. Användningen av ved och träkol, som kommer från

skogstillgångarna, står för runt 99 % av hushållsenergi användningen och det orsakar avskogning.

Regeringen i Malawi har nyligen introducerat ett åtgärdsprogram som heter Promotion of

Alternative Energy Sources Programme (PAESP) med syftet att minska användningen av ved och

träkol. Ett av bränslena som ingår i programmet är biomassabriketter. Målet med det här arbetet är

att utvärdera biomassabriketten som en hållbar alternativ energikälla till ved och träkol för hushåll i

Malawi.

Utvärderingen för det här arbetet gjordes under tre månader i Malawi. Flera ställen där briketter

producerades besöktes för att studera tillverkningsmetoder och samla ihop olika briketter.

Briketterna provades genom olika metoder och jämfördes sedan med ved och träkol.

I dagsläget används flera olika produktionsmetoder i Malawi, med stora skillnader i hur tekniskt

avancerade och kostsamma de är. Maskiner producerade från trä med enkla mekaniska lösningar

kan producera samma presskrafter som mer avancerade stålpressar. De verkar även lämpligare än

de gjorda i stål, vad gäller pris och tillgänglighet.

Merparten av producenterna i Malawi använder återvinningspapper som utgångsmaterial. Även om

pappersbriketterna är bra, så kommer andra material behöva användas om produktionen ska öka

betydligt.

Briketterna brinner bra i de populäraste spisarna i Malawi, inklusive den välanvända träkolspisen.

Medan ved är billigare att använda än andra tillgångliga bränslen så verkar det som att briketter kan

konkurrera med bränslekostnaderna för träkol.

V

Acknowledgements We would like to thank everybody who helped us through our work, especially:

Mats Söderström

-For supervising our work

Dr. Charles Kafumba and the staff on Department of Energy Affairs in Malawi

-Making it possible to carry out with the thesis and supervision

Per Lindskog and Kenneth Nyasulu

-Mediate contacts

Annie Kamanga

-Helping us in the various tests

Kyle and Amy Guerrero

-Great accommodation and minibus service

VII

Acronyms 3SF Three-Stone Open Fire

CCS Charcoal Ceramic Stove

CCT Controlled Cooking Test

CEEDS Centre for Energy, Environment and Development Studies

CWAG Chembe Women's Aquaculture Group

DoE Malawi Department of Energy Affairs

FWS Firewood Ceramic Stove

GoM Government of Malawi

HHT Household Test

LPG Liquefied Petroleum Gas

MK Malawi Kwacha

MASEDA Malawi Socio-Economic Database

MEP Malawi Energy Policy

MWBT Modified Water Boiling Test

NGO Non-Governmental Organization

PAESP Promotion of Alternative Energy Sources Programme

PAMET Paper Making Education Trust

ProBEC Programme for Biomass Energy Conservation

SIDA Swedish International Development Agency

WBT Water Boiling Test

WESMA Wildlife and Environmental Society of Malawi

WICO Wood Industry Corporation of Malawi

WWF World Wide Fund for Nature

Exchange rates of currencies, 2006-12-31:

1 EUR = 190 MK

1 SEK = 20 MK

IX

Table of contents

1 Introduction....................................................................................................................................... 1 1.1 Problem Statement .................................................................................................................... 1 1.2 Aim............................................................................................................................................ 3 1.3 Study Boundaries ...................................................................................................................... 3 1.4 Method ...................................................................................................................................... 3

1.4.1 Visits at production sites ................................................................................................... 4 1.4.2 Testing of briquettes .......................................................................................................... 4

1.5 Constraints................................................................................................................................. 5 2 Frame of Reference........................................................................................................................... 7

2.1 Household Energy in Malawi.................................................................................................... 7 2.1.1 Cooking Stoves.................................................................................................................. 8

2.1.1.1 3-stone open fire ........................................................................................................ 8 2.1.1.2 Improved Ceramic Stoves.......................................................................................... 9

2.2 Biomass Briquettes.................................................................................................................. 10 2.2.1 Raw materials .................................................................................................................. 10 2.2.2 Shapes.............................................................................................................................. 11 2.2.3 Briquette burning............................................................................................................. 11

2.2.3.1 Airflow..................................................................................................................... 11 2.2.3.2 Ash Removal............................................................................................................ 12 2.2.3.3 Positioning in fire..................................................................................................... 12

2.3 Briquette Production ............................................................................................................... 12 2.3.1 Raw Material Collection.................................................................................................. 13 2.3.2 Material Processing ......................................................................................................... 13 2.3.3 Pressing............................................................................................................................ 13

2.3.3.1 WU-Presser .............................................................................................................. 14 2.3.3.2 Screw presser ........................................................................................................... 15 2.3.3.3 Hand pressed............................................................................................................ 16 2.3.3.4 Heated die screw press............................................................................................. 16

2.3.4 Drying.............................................................................................................................. 17 3 The visited production sites and their briquettes ............................................................................ 19

3.1 Department of Energy ............................................................................................................. 19 3.2 Orphanage in Ndirande, Blantyre............................................................................................ 20 3.3 PAMET, Blantyre.................................................................................................................... 21 3.4 WESMA, Lilongwe................................................................................................................. 23

X

3.5 MIRTDC, Blantyre.................................................................................................................. 24 3.6 Nordin Family, Chitedze ......................................................................................................... 26 3.7 CWAG, Cape Maclear ............................................................................................................ 27 3.8 WICO, Blantyre ...................................................................................................................... 30

4 Tests ................................................................................................................................................ 33 4.1 Water Boiling Test .................................................................................................................. 33

4.1.1 Method............................................................................................................................. 33 4.1.1.1 Modified Water Boiling Test ................................................................................... 33

4.1.2 Realization....................................................................................................................... 35 4.1.2.1 The WBT for comparing the fuels ........................................................................... 36 4.1.2.2 The WBT for comparing stoves............................................................................... 37

4.1.3 Results ............................................................................................................................. 37 4.1.4 Sources of Error............................................................................................................... 38 4.1.5 Analysis ........................................................................................................................... 39

4.1.5.1 Fuels......................................................................................................................... 39 4.1.4.2 Stoves....................................................................................................................... 42

4.2 Controlled Cooking Test ......................................................................................................... 44 4.2.1 Method............................................................................................................................. 44 4.2.2 Realization....................................................................................................................... 44 4.2.3 Results ............................................................................................................................. 45

4.2.3.1 Sources of Error ....................................................................................................... 46 4.2.4 Analysis ........................................................................................................................... 46

4.3 Household Test........................................................................................................................ 49 4.3.1 Method............................................................................................................................. 49 4.3.2 The Household................................................................................................................. 49 4.3.3 Realization....................................................................................................................... 50 4.3.4 Results ............................................................................................................................. 50 4.3.5 Analysis ........................................................................................................................... 50

5 Discussion ....................................................................................................................................... 53 5.1 What makes a good briquette? ................................................................................................ 53 5.2 What presser to use?................................................................................................................ 54 5.3 The market for briquettes ........................................................................................................ 55

6 Conclusion ...................................................................................................................................... 57 7 Proposal to further work ................................................................................................................. 59 8 References....................................................................................................................................... 61 9 Appendices...................................................................................................................................... 63

XI

List of Tables

Table 1: Efficiency of cooking stoves..................................................................................................8

Table 2: Fuels and stoves in MWBT .................................................................................................37

Table 4. Results for comparing stoves from WBT ............................................................................38

Table 5: Energy results from the tests compared with the theoretical values....................................43

Table 7: Average values of the results gained from the CCT............................................................47

1

1 Introduction

”By the year 2020, Malawi, as a God-fearing nation, will be secure, democratically mature,

environmentally sustainable, self-reliant with equal opportunities for active participation by all,

having social services, vibrant cultural and religious values and a technologically driven middle

income country”.

This vision was announced by the former president of Malawi, Dr. Bakili Muluzi, in March 1998. It

is understandable why the president find a sustainable environment to be important for Malawi,

since about 90 % of the energy used in the country derive from forest resources. (MEP, 2003)

Unfortunately the handling of forests in Malawi is not sustainable today. Every year 2.5 % of the

total forest in Malawi disappears according to government statistics (MASEDA, 2002). The reasons

are various, but the extensive use of forest as resource for providing firewood and charcoal, is one

of them.

Malawi is one of the poorest countries in the world, with 65 % of the population living on less than

US$1 a day (MEP, 2003). The industrial sector in Malawi is small and the country's energy is

almost exclusively used in households. Hence a situation where the forest is disappearing mainly

affects the ability for households to meet their energy needs, which is most commonly spent on

cooking.

The deforestation also causes increased amounts of silt in rivers creating seasonal dry ups, trouble

for hydro power generation, and occasional flash floods, which threaten lives and infrastructure in

the riverbanks. Furthermore it leads to sedimentation in lakes which threatens the biodiversity of

fishes (MEP, 2003).

1.1 Problem Statement

The problem in Malawi is a misuse of the existing energy resources. If new more efficient methods

to use the energy could be found the energy situation could be sustainable and the deforestation

problem could be ameliorated.

For cooking, the major part of the population use firewood on an open fire, with a low efficiency.

2

The main reason why firewood is not more efficiently used is that the fuel can be collected for free

by most Malawians. The charcoal production today is another example of how the energy is used in

an inefficient way. Most of the charcoal in Malawi is produced with traditional charcoal

carbonization technologies with a proven efficiency of about 10 %. The production of charcoal is an

easy income source for producers, there is no need for investments or an economical capital to start

producing charcoal. For the households charcoal is also a relatively convenient fuel since there is no

need for advanced stoves or equipment to use it.

The Government of Malawi (GoM) has tried to take control over the charcoal production but never

really succeeded. Laws and legislations have been introduced in order to reduce the environmental

impact that is related to the charcoal production. Hence a licence is needed to produce charcoal

legally. At present there is no producer in the country that has this licence. One of the major

problems with these laws and regulations is that there are no alternative income sources to offer the

illegal charcoal producers. At the moment it is also difficult for the households to find alternative

energy sources on the market that can compete with the availability of charcoal.

The lack of capital among most households in Malawi makes it difficult to move from using either

firewood or charcoal, to more advanced energy sources where even small initial investments must

be made, for buying for example more advanced stoves or burners. Hence the substitute to these

fuels needs to require a minimal capital investment, be as cheap and accessible as charcoal and

firewood are, and at the same time be environmentally sustainable.

In order to fight the deforestation and reduce the dependence of the forest as a resource for energy,

the Department of Energy (DoE) in Malawi launched a project called ”Promotion of Alternative

Energy Sources Programme” (PAESP) in the year 2006. The aim of this project is to encourage the

use of energy sources other than firewood and charcoal.

One of several alternative energy sources considered in this project is the biomass briquette (see

illustration 1). Other alternatives include the biogas, Liquefied Petroleum Gas (LPG), ethanol and

gel-fuel technologies. It is though evident that none of these latter alternatives can compete with the

biomass briquette, in terms of the low capital investment that is required to use it.

3

Illustration 1: A typical biomass briquette made of compressed paper and sawdust.

An evaluation study about this fuel was carried out in Malawi the year 2000 (CEEDS, Biomass

Briquette Extension, Production and Marketing), and then proved it to be a cheap alternative to

both firewood and charcoal. Since some of the conditions for the biomass briquettes may have

changed during the past six years, a new evaluation is needed to update on the information and thus

validate whether this situation still obtains. That leads us to the aim of this thesis.

1.2 Aim

The aim of this study is to evaluate the viability of biomass briquettes as a sustainable alternative

energy source to firewood and charcoal for households in Malawi.

1.3 Study Boundaries

The briquette evaluation will be made in terms of physical and chemical characteristics (like

material content, size, weight, energy content), costs for the fuel and usability in household cooking

stoves. The feasibility of the production method for each briquette type will also be evaluated. The

briquettes will be compared with the characteristics of firewood and charcoal. This report does not

include an evaluation of the social obstacles related to the use of biomass briquettes in households.

It neither includes an elaborate market research or how the supply could meet the demand for

biomass briquettes in Malawi.

1.4 Method

To carry out this study a journey was made to do field studies in Malawi for 3 months, partly

4

financed by the Minor Field Study scholarship, given by the Swedish International Development

Agency (SIDA). The study has been made with support by the DoE in Malawi.

1.4.1 Visits at production sites

To get knowledge about the current status of the briquette production in Malawi visits to various

manufacturers was done. The selection of places to visit was mainly done with help from the

Department of Energy. During those visits an official from the DoE was always present. Visits

made without the assistance of DoE was made at WESMA in Lilongwe and the Nordin family in

the village Chitedze. At each site persons responsible for the production were interviewed about the

briquette making activities and the used facilities were then seen. From each producer that was

visited briquettes were collected to be examined further. At some sites the production was not

running anymore, for various reasons, but every site had samples to give us anyway, although some

of them might have been old.

1.4.2 Testing of briquettes

In order to make a statement about the briquettes as an energy source several tests were carried out.

The various tests were made over a period of about two months and the necessary equipment was

borrowed from ProBEC, based in Mulanje.

The performance of the briquette types was compared among themselves and with firewood and

charcoal. All the tests were made in a firewood cooking stove (FWS) except the charcoal where a

charcoal stove (CCS) was used. The FWS was recommended for burning the briquettes by CEED

(2000). The test made at this stage was a modified water boiling test (MWBT).

Performance comparisons for the different stoves were also carried out. The stoves tested were a 3-

stone fire, a FWS and a CCS. The fuels used for comparison in these tests were paper briquettes

from PAMET, softwood and charcoal. The same MWBT as in the fuel testing was applied for the

stove testing.

To make the comparison between briquettes, charcoal and firewood more complete, a Controlled

Cooking Test (CCT) was made for each fuel. A meal consisting of nsima and vegetables was

prepared by a local woman on a FWS and a CCS. The briquettes used in this phase were the ones

made by the DoE.

5

Furthermore, one household was asked to use briquettes for cooking, in order to evaluate how user

friendly they are and if there are any practical obstacles connected to the use of briquettes in the

household. The testing lasted a week and the briquettes used during this time were produced by

WESMA.

1.5 Constraints

The limited amount of available briquette samples from the producers affected the amount of tests

that could be made. To assure the results of the tests (it is considered that) every test should be

repeated at least three times. This is something that was not always possible, due to the lack of

available fuel. The majority of the briquettes were collected in the Blantyre area, which is a few

hours drive from Lilongwe, where the tests was made.

The weather might have affected the results of the tests. Wind and temperature were not constant

throughout all the tests, although a lot of effort was made to make the tests in sheltered environment

to minimize the chances for the wind to influence the heat transfer from stove to pot. The tests were

carried out during the months of November and December. This year the rainy season started

approximately in early December, which brought cooler temperatures and moister air compared to

the previous month. Most of the WBT was made in November before the rain, but all the CCT were

made in December at the same time each day.

7

2 Frame of Reference

2.1 Household Energy in Malawi

As seen in the second pie chart in Diagram 1, the household sector accounts for over 80 % of the

energy demand in Malawi. 99 % of the energy used by this sector is coming from biomass energy

sources (the remaining 1 % comes mainly from electricity and paraffin). Approximately 4 % of the

households have access to electricity.

Diagram 1: Energy consumption in Malawi displayed by source and end-user. (World Bank,1996)

About 85 % of the Malawi population, consisting of 12 million

inhabitants, live in rural areas. The urban population is mostly

found in the four biggest cities; Blantyre and Lilongwe (country

capital), both having about 500'000 inhabitants each, and the

smaller Zomba and Mzuzu, with populations of around 100'000

each. A map of Malawi with the biggest cities is shown in

illustration 2.

In rural households almost exclusively firewood is used, when

cooking. The firewood is normally taken from trees on the

farmland or in the nearby forests, for free.

In urban areas most of the firewood users collect the wood from

nearby trees for free, while about half of them sometimes buy

firewood. The firewood is normally sold in street markets.

Illustration 2: Map of Malawi,

showing the locations of the four

biggest cities: Lilongwe, Blantyre,

Zomba and Mzuzu.(CIA,2006)

8

For the urban households that have to buy their fuel, an alternative to firewood is charcoal. Charcoal

is made in earth kilns in rural areas and is sold in the cities, where the demand for fuel is high. The

charcoal is a more convenient fuel in a way, since it has got a higher heat value (J/kg) than firewood

and less smoke emissions, once it has started glowing. On the other hand, the price of charcoal is

normally higher than the price of firewood (counted in money spent per meal). Therefore the fuel is

mostly used by middle- to upper-income households. (World Bank, 2005)

The charcoal is almost exclusively made from hardwood, taken from indigenous forest. The GoM

has tried to promote softwood charcoal, made from planted pine trees, but since the quality of this

charcoal is not as good as the former alternative, households still buys the hardwood-based

charcoal. The kilns where the charcoal is made are inefficient. To produce one ton of charcoal 7

tonnes of firewood is needed. (GoM, 2003)

2.1.1 Cooking Stoves

There are several cooking stoves that can be used for biomass energy in Malawi. The most simple,

and affordable one is the 3-stone open fire. Other alternatives are the ceramic stoves. Those are

more expensive to buy but they cook with better efficiency. The efficiencies of the three most

common stoves are shown in Table1.

End use device Efficiency

3-Stone Fire 10 %-14 % Firewood Cooking devices

Improved Fire Wood Ceramic stove 20 %

Charcoal Cooking Devices Improved Charcoal Ceramic stove 35 %

Table 1: Efficiency of cooking stoves. (MEP, 2003)

2.1.1.1 3-stone open fire

In African countries the 3-stone open fire (3SF) is widely

used for cooking with firewood (see illustration 3). In

Malawi 91 % of the urban firewood-using households

prepare their meals on this open fire, according to the

Malawi Energy Policy (GoM, 2003).

Illustration 3: 3 stone open fire

9

The stove consists of three stones placed on the ground, forming the edges of something like a

triangle, which holds the pot a decimetre or two above the ground. Underneath the pot firewood is

pushed in from different angles. The “stove” is inefficient, since much heat is lost to the

surrounding environment. The advantage of this cooking device is that it is free and easily

assembled (you just need three stones).

2.1.1.2 Improved Ceramic Stoves

One way of decreasing the use of biomass energy for cooking is to change the end use device. If

more efficient stoves are used, less fuel is needed to cook the same amount of fuel. Therefore the

DoE has been recommending ceramic stoves to the public. These stoves are made from recycled

metal, and are lined with about 3 cm of clay on the inside. The clay insulates the combustion

chamber against the environment (although some of the heat is absorbed by the material) and hence

more heat is transferred to the pot. The stoves are sometimes given the epithet “improved” because

they are a better version of the older and simpler metal stoves (without the clay lining).

The charcoal and firewood have different burning characteristics and the stoves need to have a

suitable design for each fuel. While firewood transfers most of the heat by convection through the

flames, charcoal transfers heat by radiation. When charcoal is used for cooking the fuel should be

placed close to the pot to get the most efficient transfer of heat radiation. On the other hand, the

firewood needs some space above the fuel for the hot flames. Hence the pot needs to be placed at a

higher level when firewood is used, comparing to when charcoal is used. The designs of the ceramic

stoves are displayed in illustration 4.

Illustration 4: Firewood ceramic stove and charcoal ceramic stove.

10

The firewood stove also has a shape that demands an opening (with or without hatch) where the

firewood sticks can be pushed into the fire. (Interview with Andi Michel)

The charcoal ceramic stove (CCS) is the most common stove to use in Malawi and other African

countries when burning charcoal, while few households use the FWS when burning firewood.

Although the FWS is not close to being used as much as the 3SF, the stove is interesting in this

study, since the Department of Energy is promoting this stove for firewood users.

2.2 Biomass Briquettes

The biomass briquette is a fuel, consisting of biomass, such as agricultural waste or waste paper,

bound together and compressed into small pieces (approximately 5 to 15 cm). The fuel complies

with the energy needs for poor households in developing countries, where firewood and charcoal is

normally used. Briquettes are very seldom used in Malawi today. There are few producers in the

country and the fuel is hard to find for consumers. If nothing else is stated, the information about

biomass briquettes in this chapter is based upon facts found in the book Fuel Briquettes: Theory

and Applications from around the World (2003), written by Richard Stanley for the Legacy

Foundation.

Richard Stanley has a lot of experience in briquette production and he has got great knowledge

about briquettes. Richard Stanley has also tried to introduce biomass briquettes as a household fuel

in Malawi a few years ago.

2.2.1 Raw materials

A lot of different materials can be used for briquette making, for example agricultural residues like

ground nut shells, straw, tree leaves, grass, rice and maize husks and banana leaves. It is also

possible to use already processed materials such as paper, saw dust and charcoal fines. Although

some materials burn better than others, the selection of raw material is usually most dependent on

what is easily available in the surrounding areas of where the briquettes are made. Of course a

briquette can consist of a blend between many different raw materials.

The inflammability is not the only thing that matters when the raw material is being selected.

Another important characteristic is its ability to bond together, when compressed. For these reasons

fibre-rich materials are good. When these materials are soaked in water and partly decomposed, the

11

fibres in the material are able to create strong bonds.

The calorific value of a basic paper/sawdust briquette will be around 15 MJ/kg. This value will of

course differ depending on the selection of raw materials. It can be compared to firewood that is

around 16 MJ/kg (dependent on moisture content) and Charcoal around 30 MJ/kg (CEEDS). These

values should not be confused with the energy gained from the briquette when burned in different

stoves.

2.2.2 Shapes

The size of the briquette has an influence on in which stove that it can be used, since it must be able

to fit into the combustion chamber. The most common type of briquette is the so called doughnut

shaped one. It has got a cylindrical shape with a hole in the middle. If burned properly, the central

hole increases the combustion efficiency of the briquette, states the Legacy Foundation. In order to

make these briquettes a presser is needed. The diameter of the briquettes is affected by which

pressing equipment that is used, but usually they measure between 10 and 15 cm.

In Low Input Food and Nutrition Security: growing and eating more using less (World Food

Programme, 2005) the author Stacia Nordin describes a way to make paper-based briquettes

without the use of pressing equipment or tools. Paper that has been soaked for about half a day is

squeezed by hand in shapes of balls or similar. The balls are then left to dry in 1-3 days, before they

are ready for use.

In the section called ”Briquette Production” further below, the briquette pressing is described in

greater detail.

2.2.3 Briquette burning

Below the most important theories about briquette burning is described. Richard Stanley states that

there are three important factors that affect the fire when briquettes are used. Those are air flow, ash

removal and positioning of the briquettes in the stove.

2.2.3.1 Airflow

Good airflow is critical for the burning of briquettes, as for other fuels. The optimal fire is reached

12

when the airflow comes from underneath the fuel. Insufficient air flow will result in a smoky fire,

since the released volatile gases will not be completely combusted.

2.2.3.2 Ash Removal

The briquettes produce more ash than both firewood and charcoal. This can cause a problem in

some stoves, where the air holes can get clogged, which affects the airflow. Legacy Foundation

claims that the air holes in the bottom of a stove needs to have at least 1.5 inches (~37 mm)

diameter, to be suitable for briquettes. The charcoal and firewood ceramic stoves do not comply

with this rule since their air holes only have a diameter of about 0.75 inches. When using briquettes

in a 3-stone open fire, extra tendering may be needed to remove ashes from the fire under the pot.

2.2.3.3 Positioning in fire

The positioning of the briquettes in the stove influences the burning characteristics. The briquettes

can either be burnt just like they are, or they can be broken into smaller pieces. The former method

is considered to make the combustion more long-lived, but less intense than the latter, although the

ignition of the briquette is made more difficult.

If the briquettes are burned without tearing them apart, doughnut shaped briquettes should be placed

in an upright position (i.e. having the inner hole facing upwards). This helps the air to pass through

the central hole in the cylinder, which makes the combustion much more efficient, states the Legacy

Foundation. The reason for the higher efficiency is because the radiant energy from the burning

material is facing inwards, and not out from the fire. This characteristic makes the briquettes

suitable in stoves with low efficiency, since the impact of the heat losses are greater in those cases.

The hole also creates a draft through the central hole, similar to that of a chimney, which gives a

clear path for good air-flow from underneath the briquette.

2.3 Briquette Production

The making of briquettes is divided in four main steps, as described in the manual Fuel Briquettes:

a Users Manual (Legacy foundation, 2003).

13

2.3.1 Raw Material Collection

As said before, a lot of different ingredients can be used for briquette making. Burnable, fibre-rich

material that is both available nearby and that can be taken free of charge is preferably selected. The

manual labour required for the collection of material will then be the only related cost for getting

hold of raw material.

2.3.2 Material Processing

To make briquettes the raw material should be pressed together, but before this, the material has to

be prepared. The preparation is necessary to release and distribute the fibres in the material. This

makes the materials more susceptible to bond when compressed in the presser.

The organic matter, like agricultural residues, first needs to be chopped or pounded into smaller

pieces in dry condition. Then it should be left to partially decompose in order to loosen up the

structure of the material. How long time the decomposition takes varies and depends on the material

and the climate. After the different materials have been decomposed properly they should be soaked

in water and blended. This makes the fibres to randomly distribute in the sludgy matter that is

created.

If the briquettes are to be made out of waste paper the preparing process is different, and much

easier. The paper must be soaked in water for about half a day, or more, and then it should be

shredded and pounded into small pieces. When this is done the material is ready to be pressed into

briquettes.

The pounding of raw material, whenever it is necessary during the preparations, are the most

laborious and time consuming phase in the production chain. The pounding is usually made using

large mortars and pestles (about ~1.5m tall).

2.3.3 Pressing

For the material to be de-watered and to bond, it is necessary to submit it to pressure. The method

of pressing will affect the final shape and burning characteristics of the briquette. A higher density

gives the briquette a higher heat value (J/kg), and makes the briquette burn more slowly.

The most common type of the briquettes is the cylindrical shaped, often with a centre hole

14

(doughnut shape). To press this type of briquette it is necessary to use a cylindrical mould, most

commonly a perforated tube of PVC, placed in upright position. In the centre a metal piston can be

placed which enables the making of a hollow shaped doughnut briquette. The tube is then filled

with raw material. The raw material in the cylinder is then

compressed by descending a disc or a solid cylinder that just fits

in the PVC tube.. Water, blended in the raw material, leaves the

tube through the perforated holes during the compressing phase.

An example of this equipment is shown in illustration 5.

When compressing the briquette the compression of raw

materials requires a non linear force to distance1. There are

different ways of applying the force for pressing cylindrical

shaped briquettes. Two common technologies are explained

below.

2.3.3.1 WU-Presser

The WU-presser was developed by the Washington University more than ten years ago. It is

constructed from either metal or wooden parts. The wooden version has been seen in Malawi at

least since 1997 (illustration 6).

Illustration 6: A wooden WU-press in Malawi.

1 When the disc first starts forcing the raw material to compress downwards, the first centimetre travelled by the disc

needs a lower amount of work (since the raw material in the tube contains a lot of air and water that is easy to

squeeze), if compared to the work that is necessary during the last centimetre of the pressing movement.

Illustration 5: Mould kit for making

doughnut briquettes

15

There are a few reasons why the wooden version grew popular. Wood is a cheaper material and

more available than metal in Malawi and because of the lack of financial means in the country the

wooden press had the economical advantage. Another reason was the high availability of skilled

manpower for producing in wood. (CEED, 2000)

Illustration 7: How to use the WU-presser.(Legacy Foundation, 2003)

The WU presser is pressing the briquette in three steps described in illustration 7. Each step will

press with increasing pressure. This takes advantage of the non linear force to distance property of

briquette pressing described earlier.

2.3.3.2 Screw presser

The screw pressers also make briquettes in upright cylinders. The raw material is compressed by

lowering a metal disc which is moved vertically by a screw that is turned by hand. The disc moves

approximately 1cm/rev, with a constant exchange ratio of the force. The screwing technology is

powerful and becomes handy in the final compression stage where it is able to contribute fully with

its advantages of a good exchange ratio of forces.

The screw press is most commonly made in metal. This makes it sturdy but often quite expensive.

Richard Stanley, who is promoting the WU-press press through Legacy Foundation, claims that a

press using screwing parts is not suitable for an environment where briquettes are made, since there

is too much of granular and wet material around that may cause damages on the screw threads.

16

Illustration 8: Instruction paper on how to

make hand pressed paper briquettes. (Art by

Kristof Nordin,2005)

2.3.3.3 Hand pressed

As Stacia Nordin claims in “Low Input Food and Nutrition

Security: growing and eating more using less” (World Food

Programme, 2005) the briquettes can be pressed by hand,

using waste paper as raw material. This method does not

require any use of pressing equipment or tools, which

makes it cheap and available to everybody. The method is

though explained only for making paper-based briquettes,

and not for using agricultural residues. Illustration 8 is the

instruction of how to make these briquettes from the book.

2.3.3.4 Heated die screw press

The heated die screw press is an industrialized machine for

producing briquettes. It uses the natures own binder, lignin.

When heating up the biomass to 300°C the lignin melts and

when cooled down again it stiffens and the briquette will get

the desired shape.

In illustration 9 a principal sketch of a heated die briquetting machine is shown. In the funnel (1) the

biomass is gathered. It drops down on the screw (3), which is driven by an electrical engine (4).

The screw presses the biomass into

the die (2). Along the die there are

grooves to prevent the biomass to

rotate with the screw. The die is

electrically heated and heats up the

biomass to 300°C so that the lignin

melts. The briquette is extruded (5)

and chopped off in desired length.

The briquette will be hollow and have

a pyrolyzed surface from the heating.

Some machines heat up the biomass before it goes into the screw. This decreases the wear on the

screw and die. To a small extent it saves the energy needed for rotating the screw.

Illustration 9:Simple sketch of a heated die scew press

17

Besides the cost of the investment the machine also has a cost for the electricity consumed. Another

cost is the screw that gets worn and has to bee replaced frequently.

2.3.4 Drying

After the briquettes are made they have to be left to dry, usually between 3 and 8 days. The number

of days depends on the weather conditions, during the dry season it is a lot quicker.

19

3 The visited production sites and their briquettes

In the following chapter all the visited briquette producer are described, based on observations and

interviews at the production sites. The briquettes produced at each site are described with a picture

and some basic physical facts. The pressure stated is from brief calculations found in appendix 4.

3.1 Department of Energy

Raw materials: Paper, sawdust

Press: Stanlink

Shape: Doughnut

Outer diameter: 100 mm

Inner diameter: 26 mm

Height: 48 mm

Weight: 117 g

Density: 0.36 kg/dm3

Pressing pressure: 1.7 MPa

Comments: Made by staff at the DoE for

marketing and demonstration

purpose.

Department of Energy has made briquettes for exhibition and marketing purposes. Those are made

using the wooden WU-presser. DoE has several such pressers at the BARREM office in the

outskirts of Lilongwe. The briquettes made by the DoE were stored at the ProBEC office in

Mulanje. The briquettes consist of waste paper and sawdust.

During a visit to the BARREM office some briquettes were made together with staff from the DoE.

The purpose of the visit was to get an idea of the briquette making process. Briquettes were made

from paper and different additives.

20

3.2 Orphanage in Ndirande, Blantyre

Raw materials: Paper, sawdust

Press: Stanlink (without iron

piston)

Shape: Cylindrical


Height: 70 mm

Weight: 163 g


Price: Only produced for own use

Comments: Slightly irregular shape in

between the briquettes

In the township of Ndirande in Blantyre disabled people make briquettes at an orphanage. The

briquettes are made for own use only, and are not sold to the public. A wooden WU-presser is used.

The piston has been missing, so the briquettes can not be made in a doughnut shape as intended,

instead they are solid. The machine is only used once a week. This is enough for covering the

demand of briquettes that they have. Raw materials used are paper waste and sawdust that is

transported to the site for free. Initially the briquette production at this site started with help form

the Nkhomano Development Centre. There is apparently no communication between the orphanage

and Nkhomano anymore, the reason is unclear.

21

3.3 PAMET, Blantyre

Raw materials: Paper, sludge from Unilever

(residue oil from food

processing)

Press: Screw press

Shape: Doughnut



Height: 50 mm

Weight: 295 g


Pressing pressure: 1.8 Mpa

Price: 5 MK

Comments: Bad smell from the sludge

The non-profit organization Paper Making Education Trust (PAMET), based in central Blantyre,

developed in the 90's a press based on the screw technology. The press is made from metal parts

that are bolted together. The machine costs 28'000 MK (of which the mould contribute the costs

8'000 MK). The press uses one mould, where two

briquettes can be made at the same time, using a

divider plate. See illustration 10 of the presser in use.

The briquettes at PAMET are made of waste paper,

coming mainly from the Blantyre Print and Packaging

(BPP). Sometimes PAMET has to drive and fetch the

waste. The waste is being used both to produce

recycled paper and to produce briquettes. According

to PAMET there is an increasing demand for waste

paper in Blantyre, from different stakeholders. Some

paper is even being exported on trucks to Zimbabwe

and Mozambique, for industrial recycling.

Also some small amount of sludge (containing oil) is

added to the waste paper, to increase the combustion Illustration 10: Screwpresser in use at PAMET

22

performance. This sludge is delivered free of charge from Unilever in Blantyre, where the sludge

comes out as a by-product form this food industry. The sludge was kept in a bucket and did not

seem to be very pleasant to work with, since it is greasy and containing a mix of unidentified

ingredients.

The organization has one person employed for producing briquettes. This person produces about

100 briquettes per day. The demand is increasing so Moses Binali, executive director for PAMET,

is considering employing another person for extending the briquette production.

Normally the waste paper is collected about once a week, and stored at PAMET. In the afternoon

the employee soaks the wastepaper that he is going to use for briquette production the day after.

Next morning he pounds the waste paper and then he uses the presser to produce briquettes from the

pounded material.

The briquettes are sold in the township of Chilomoni in Blantyre. PAMET delivers the briquettes

with a vehicle to the salesmen in this township. Some briquettes are also sold at the PAMET office

in Blantyre. Briquettes sold by PAMET to the end consumer are sold for 5 MK/each, whereas they

are sold to the salesmen in Chilomoni for 3 MK/each. At the moment 3 persons are selling

briquettes for them. PAMET is not producing briquettes for making profit, but for marketing the

product, as an alternative energy source to charcoal and firewood. Sometimes PAMET hosts

marketing events of the briquettes in townships around Blantyre. They demonstrate how easy it is to

cook beans, talk about how clean the briquettes are and try to explain the whole situation of the

deforestation and how it is caused by firewood. The event lasts for a day.

It should take no more than four PAMET briquettes to make nsima for a normal household, says

Moses Binali.

PAMET has trained a number of women in briquette manufacturing and a few years ago there was

production running by women groups (with support from NGO's and church groups) in different

parts of Blantyre, but today Moses Binali does not know of anybody who is still making briquettes,

apart from PAMET itself. According to him, the reason is the increasing difficulty of collecting

waste paper, especially in the rural areas. If there is no raw material to be found, the production can

not continue. PAMET sold a few pressers to the women groups which were trained by them. The

presser that is sold is a smaller version of the one used by PAMET.

Moses also claims that the waste paper in Blantyre is not by any means enough for producing

23

briquettes for the whole Blantyre region.

PAMET is an organization financed by NGO's. They do try to make profit so that it would be

economically sustainable if the NGO's would retract their funds. The incomes are generated from

selling recycled paper and briquettes.

3.4 WESMA, Lilongwe

Raw materials: Paper

Press: Screw press

Shape: Doughnut shape


Height: 70 mm

Weight: 163 g

Density: 0.3 kg/dm3


Price: 20 MK for a bundle of four

briquettes

Comments: Irregular shape in between

the briquettes

A few years ago Wild Life and Environmental Society of Malawi (WESMA) started a briquette

production project at the National Sanctuary in Lilongwe. Staff from WESMA made a visit to

PAMET in Blantyre to learn about briquette making. WESMA also bought a presser (the same that

PAMET uses today) through PAMET, for the production.2

Raw material for the production at WESMA was office paper, given by offices in City Centre. The

paper was dumped free of charge by companies or NGO's, at the National Sanctuary, where it was

stored in two containers. The briquettes were sold in street markets in Lilongwe, and at the

WESMA office in the Natural Sanctuary.

Around “one year” ago, the responsibility of the production was given over to two persons

employed by WESMA. The people made briquettes, but there started to be a problem with the

2 Except for the presser from PAMET, that was bought for a few thousand MK, WESMA was also given a presser as a donation from some person. This machine is a screw press, and looks really durable, but has not been used

at any time.

24

market. There were more briquettes produced, than what could be sold. So the persons were then

given also the responsibility to market the briquettes that they produced. For some reason this was

not very easy, so after a few months the two employed briquette makers resigned. Instead of

shutting down the production, WESMA gave a group of ten women the opportunity to use their

facilities for producing briquettes. The women made briquettes for a few months, until the

production stopped about one month ago. The reason given for the stop was that they could not find

any market for the briquettes.

Today there is no production at WESMA in the Natural Sanctuary. All the facilities are there, but

nobody is using them. There is a storage room filled with hundreds of paper briquettes that were

made before. The containers for raw materials are still there, with quite a lot of paper in them. The

presser that was bought through PAMET is partially broken. The machine can still be used,

although the joint between the screw and the pressing disc is broken. (George Bokosi, 2006)

3.5 MIRTDC, Blantyre

Raw materials: Paper, sludge from Unilever

(residue oil from food

processing)

Press: MIRTDC screw press




Height: 53 mm

Weight: 330 g



Comments: Very hard packed, Bad smell

from the sludge.

The Malawi Industrial Research and Technology Development Centre (MIRTDC), in Blantyre,

together with some other organizations, developed a new press which was ready for the market in

1999. This project started in 1998, hoping to be able to construct a presser that could make 20

briquettes at the time, instead of only one, as did the older pressers. It was then discovered that the

force applied for pressing such amount of briquettes in one move was too big.

25

The final version of the MIRTDC press that came out on the

market can make 12 briquettes at the same time, using 6

cylinders, each producing 2 briquettes. See illustration 9 of the

press. The force on the cylinders is applied by lowering a metal

disc that squeezes the raw materials in all the 6 cylinders at the

same time, instead of just working on one cylinder which is

most common. The metal disc is moved up and down by

screwing. The crank handle is tube shaped, which makes it

possible to locate a rod (like a strong broom stick or similar) to

get more leverage, when needed. The machine consists of

welded metal parts, and is made in Blantyre, after design

drawings from MIRTDC. MIRTDC sells the machine for 40'000

MK. MIRTDC says that the only buyers of this machine have

been NGO's. MIRTDC hopes that the presser could be

developed to be constructed using different, less expensive,

materials.

Since MIRTDC did not present any record of the buyers of this product, it was not possible to find

any users of the machine. MIRTDC though offered to test the exhibition machine in the MIRTDC

shop. Raw materials brought from PAMET, consisting of paper and sludge, were used when trying

to produce briquettes using the MIRTDC machine. With manual force the screw was turned,

pressing the briquettes. Unfortunately, the machine did not support the forces applied, so the

construction broke in one of the weldings. It is worth mentioning that a 2 meter lever was used to

turn the crank handle with two persons operating it at the same time. A person from the MIRTDC

claimed that the machine that broke was not constructed correctly, that it did not fulfil the

specification of requirements.

Illustration 11: The MIRTDC press demonstrated at their shop in Blantyre.

26

3.6 Nordin Family, Chitedze

Raw materials: Paper

Press: By hand

Shape: Spherical


Height: 48 mm

Weight: 93 g


Comments: Irregular shape

Kristof and Stacia Nordin lives in the village Chitedze, 20 km outside of Lilongwe. They are

working under a program called Never Ending Food. At their home in Chitedze and in their work

they are promoting permaculture. Permaculture is a type of sustainable agriculture on the natures

own conditions. It enables the farmers to harvest food all year around and cultivate their land

without ruining fertility of the soil. In their work they have created the “The Low Input Food and

Nutrition Security manual”, that is all about a more sustainable living. It contains information about

anything between agriculture and what food contains the necessary nutrients. One part of this

manual is about making paper briquettes from office waste paper. In their instructions they soak the

paper overnight and then, without pounding or shredding, pressed by hand into balls the next day.

They are then left to dry for 1-3 days. The briquettes are used for cooking during power failures or

for heating on a Charcoal Ceramic Stove. Similar briquettes have been made by ourselves (the

authors) at home using both office paper and newspaper.

27

3.7 CWAG, Cape Maclear

Raw materials: Leaves

Press: WWF hand press




Height: 50 mm

Weight: 186 g


Price: 2.50 MK

Comments: Very fragile, falls apart very

easily

Raw materials: Corn stalks

Press: WWF Hand press

Shape: doughnut shape



Height: 50 mm

Weight: 133 g


Price: 2.50 MK

Comments: -

The production at Panda Garden in Cape Maclear is done by Chembe Women's Aquaculture Group

(CWAG), under the support of the following stakeholders:

● HEED – Malawi

● WWF – Finland

● Rotary Limbe Club

● Rotary District

● Department of National Parks

● Department of Fisheries

28

Close to the national park is the WWF headquarter situated. Here is

also where the WWF started up the briquette project year 2003. The

organization then developed the equipment, which can be made by

people in Monkey Bay. The presser consists of metal parts and

produces doughnut shaped briquettes. Instead of using a perforated

PVC tube for the mould, a non-perforated metal cylinder is used.

The raw material is compressed using a metal plate, a smaller

cylinder and a handle that is pushed down with hand power (see

illustration 12). The metal plate is slightly smaller than the bigger

metal cylinder, which enables the water in the raw material to

escape on top of the plate.

The headquarter does still produce briquettes today, but the

briquettes are only made to supply the staff at the WWF. The site

has since 2003 served as an educational centre for people who want

to learn how to make briquettes. In Cape Maclear they today have 56 women working with

briquette production, in different sites in the village. Since the equipment is so light you can

conveniently keep it in your household. Today the centre has taught people from a number of

villages in the Mangochi area and even one from Blantyre. At the moment briquettes are produced

in four different villages in the Mangochi district, using the methods that were taught at the Panda

Garden. The 56 women in Cape Maclear, who are working with briquette production, are divided in

5 groups. Each group, containing about 10 people, work together with the production. They then

share the profit between themselves. A woman can make between 100 to 150 briquettes a day. The

briquettes are sold at the price 2.50 MK, which means that a woman working in production can

make a profit of about 250 MK per day.

The briquettes are either produced only by corn stalks or by leaves. Sometimes they add grass or

paper. Paper burns well but is expensive. The materials are collected from the surrounding areas,

free of charge. They are mixed with water in a basin for about 3 days. Then they are left to

decompose for 2 to 3 weeks, depending on the material. The corn stalks takes about 1 week more

time to decompose compared to the leaves. The decomposition makes the pounding easier, and

makes the briquettes easier to compress, in the presser. When the material has decomposed, it will

be pounded. This takes a lot of time and work. After this, the briquettes are made with the pressing

procedure. After the pressing, the briquettes are left to dry in the sun or the shade (during the rainy

season). The drying takes about 4 to 5 days, but in the rainy season it takes about 10 days.

Illustration 12:The WWF designed

briquette press used in Cape

Maclear.

29

In Cape Maclear briquettes are used just as much as firewood, claims Lois Chembe. This is due to

the deforestation problems that this area faces. The last twenty years a lot of forest has disappeared,

and the people living in Cape Maclear has to go far to collect firewood. According to Lois Chembe

it is not unusual that women spend their whole day on collecting firewood, since the transport is

done by feet and the wood is collected far up in the mountains. Before people used to pay the entry

fee for the adjacent national park (10 MK) and then collect as much firewood as possible and then

return to the village. This is illegal and the park guards now watches more carefully over its visitors.

Since it is so laborious to get firewood the prices for the fuel is high in the village. Normally you

will have to pay about the double price per useful energy unit for firewood than for briquettes,

according to Lois Chembe. The briquettes are sold for 2.50 MK a piece. Usually you will have to

use about two or three briquettes to make nsima for a household, depending on the size of the

family. The briquette is more poplar during rainy season, since the firewood in the forest is wet

then.

One household completely depending on briquettes as fuel for meeting their energy demand will

spend between 10 and 20 briquettes per day, or even more if the family is big.

One problem that the women in Cape Maclear face is that there is not enough market for the

briquettes in the village. They could easily increase production, but there is no demand for this

today. Then they must be transported to other villages, and this is not convenient.

People that are interested in briquette production can visit the site in Cape Maclear to learn how to

make the briquettes, free of charge. If they are interested to start up a new production site, they can

then apply for getting subsidies, for paying the equipment needed.

30

3.8 WICO, Blantyre

Raw materials: Sawdust

Press: Die-heated screw-

press briquetting

machine

Shape: Cylindrical with an

inner hole



Height: 400 mm

Weight: 931 g


Price: 40 MK

Comments: Hard and heavy with a

burnt surface. Inside the

hole there was dirt/ash

on our samples.

The Wood Industry Corporation of Malawi (WICO) has several sawmills in Malawi. One of them is

situated in Dedza. The facility has a briquetting machine that produces briquettes form sawdust.

The machine has been running periodically from 1984. The last time it was running was about 6

months ago. WICO bought the presser for a subsidized price from Japan. From the beginning it

produced 500 kg briquettes per day. This number has now been reduced to 300 kg. The total

amount of sawdust produced every day is about 5 tonnes in Dedza. WICO also has saw mills in

other parts of Malawi, e.g. in Zomba, where the mountain of sawdust is even bigger, according to

Aman Kunje, working at WICO.

The machine that has been used is driven by electricity, and produces a continuous briquette, which

is then manually broken into parts, each with the weight about one kilogram. The sawdust is hold

together thanks to a process where the briquette is heated on the outside, which makes a strong

shell.

The reasons why the machine is not in use today are various. One is that there is some part of the

equipment missing. Another is that the increasing demand of timber has made the manager

31

concentrating only on the main activity: timber production. One other reason is that the market for

briquettes at the moment is not reliable. Aman Kunje thinks that it still is difficult to compete with

the charcoal prices. He though thinks that if a more effective briquette machine is introduced to

produce briquettes from all the WICO sawdust, it could be more profitable, if there is proof of a

market to rely on.

WICO's briquettes consist of 100 % sawdust from their own production sites. WICO has tried to

blend the sawdust with cassava and maize husk to get better briquettes, but it was not worth the

effort. The briquette will last for a month if it is kept in normal humidity, after that it will fall apart.

This is one of the major problems with the briquette, that it is not possible to store it for a longer

period of time. It is possible to keep it longer if it is stored in dry conditions. The consumers then

refer to charcoal that can be stored for a long time without problems.

They have sold the briquettes on the market for personal use. The tea industry has been interested in

buying the briquettes but the demand could not be satisfied with WICO's small production capacity.

The price for the briquettes has risen from 5 MK to 40 MK due to the increasing electricity prices

and inflation. WICO claims that there is no possibility to invest in a new briquette press and make a

profit, due to the low prices of charcoal.

33

4 Tests

4.1 Water Boiling Test

What is interesting concerning the energy content of a briquette is how much of the energy in the

briquette that can actually be used. The useful energy is the energy transferred into the pot that is

used while cooking. If the same test is performed on each briquette and on firewood and charcoal, a

good comparison can be made. The test is called the Water Boiling Test and it will be used for

comparing:

• The briquettes with each other

• The briquettes with firewood and charcoal

• The briquettes performance on the most common stoves in Malawi.

4.1.1 Method

Stove developers around the world have developed a standardized water boiling test (WBT) to help

them in their work. This existing test, found in appendix 1, focus on comparing the efficiency of

different stoves. The WBT consists of three phases:

• High power test with cold start

• High power test with hot start

• Simmering test The high power test measures the time and fuel it takes for bringing a certain amount of water to

boil, first by using a cold stove and then a hot stove. The simmering test measures the amount of

fuel it takes to keep the water simmering for 45 minutes. It is very versatile but it takes quite a bit of

time to perform each test. Because of limited time, supply of briquettes and the fact that the focus of

the WBT is set on stove performance, a modified water boiling test (MWBT) was needed.

4.1.1.1 Modified Water Boiling Test

The information that is wanted from the MWBT is:

• How quick can the fuel bring the water to boil?

• How much energy is transferred into the water relative the amount of fuel consumed?

• Other notations (smoke, ease of ignition etc.)

34

To save time and fuel the two last phases in the original WBT (high power test with hot start and

simmering test) were combined and the 45 minutes for simmering was reduced to 15 minutes in the

MWBT. The specific time of 15 minutes is approximately the time it takes to cook the most

common food in Malawi, nsima. The time limitation makes the test closer to a true scenario. In the

beginning of the MWBT, when the water is brought to boil, a lid is used on the pot, but once the

water starts to boil the lid is taken off. The stove testers around the world still discuss if the test

should be performed with or without the lid for various reasons, but to take the lid off reminds more

of the real scenario when cooking nsima (because the need of stirring) and will therefore be used in

this test. The first phase of the WBT (test on cold-started stove) is not very necessary since it tells

more about the heat capacity of the stove than the characteristics of the specific fuel.

The WBT is designed to be suitable for comparing stove-tests that has been performed in various

parts of the world where moisture content of the fuels may differ a lot. Hence this difference should

be taken into account, so it does not affect the results in the original WBT. In the WBT the moisture

content of each fuel should be measured before using them for testing. The value is then used for

calculating the energy that is needed to vaporize this moist during the test. The calculated amount of

energy is then subtracted from the total energy that has been used in the test. Since the testing

included in this report is made to compare fuels during a limited time period (3 months) and for a

limited geographical area (Malawi), the moisture content for the fuels was not considered very

important. The true performance of a fuel is partly dependent on its moisture content and therefore

its effect should not be subtracted from the results.

The time recorded to bring the water to boil is from the moment the fuel catches fire until the

temperature of the water reaches local boiling point, and the lid is taken off. To prevent the use of

too much fuel to bring the water to boil faster, an aim is set to immediately keep the water

simmering and not heavily boiling after the lid is taken off.

The amount of energy that is transferred to the water will be calculated by measuring the increased

water temperature and the amount of water disappeared from the pot during the test. The energy

will be compared to the weight of the used fuel. This measure (J/kg) will be referred to as ‘utilized

energy’ from now on. The procedure for calculating this is described in appendix 4.

After the test, the remaining fuel in the stove will be weighed to calculate how much of that fuel

that was not combusted. This will be measured because of the limited experience of burning each

type of briquettes. It can be hard to know exactly how much fuel to put into the stove, something

35

that the consumer will learn in a few weeks.

The briquettes will produce quite a lot of ash (CEEDS 2000), therefore a formula for calculating the

proportion unused fuel and ash is developed. The formula is found in appendix 4. The ash produced

from a fully combusted briquette will be measured at the end of the testing sessions, when it will be

possible to leave the briquettes in the stove until they are fully combusted.

Every specific test shall be performed at least three times, unless there is a lack of fuel or other

practical obstacles. Three times is the number recommended in the original WBT.

The exact procedure that is set up for the MWBT is found in Appendix 2.

4.1.2 Realization

The equipment used in the

testing was a thermometer, a

scale, and the stoves. This

equipment is listed and

described in Appendix 6. The

thermometer was inserted in

the middle of the pot and the

water through a small hole in

the lid. The testing equipment

that was used is shown in

illustration 13. For each test 20

g of softwood twigs were used

to start the fire. To start the

charcoal 30 g was needed

because it is a fuel that is

harder to ignite. The amount of

twigs needed was decided by

trial and error. The testing took place in a backyard of a house in Area 6 and one in Area 43,

Lilongwe.

Illustration 13: Laboratory equipment for the MWBT

36

4.1.2.1 The WBT for comparing the fuels

The following briquettes were tested. They are all collected by us and they have different

characteristics in one way or another:

● Paper and sawdust briquette from DoE

● Paper briquette from orphanage in Ndirande

● Paper briquette from PAMET

● Paper briquette from WESMA

● Paper briquette from MIRTDC

● Leaf briquette from CWAG

● Corn stalk briquette from CWAG

● Paper briquette from the Nordin family in Chitedze

● Sawdust briquette from WICO

To get the reference to the woodfuel these were also tested:

● Softwood

● Hardwood

● Charcoal

Briquettes and firewood were tested on a firewood ceramic stove, but for the charcoal tests it would

not be fair to use that stove, since the design is not suited for charcoal burning. Instead a charcoal

ceramic stove was used, which is very similar to the firewood ceramic stove, but constructed for

charcoal use.

The briquettes from CWAG were impossible to complete a whole test with. They produced too

much smoke to be able to stay close to the stove for tendering. When they burned they produced a

big amount of ash, which filled up the stove and clogged the air holes. A decision was made to

interrupt these tests for health reasons.

The briquettes from the Nordin’s were not burning very well. They seemed slightly heavier then the

other briquettes which the calculated density confirms. High moisture content was suspected as a

possible reason and it was needed to control. To control the moisture content the briquettes were put

into an oven at 70°C to vaporize the water. They stayed in the stove until there was no weight loss

from them. The briquettes from Nordin’s turned out to have a moisture content of about 18 %,

which can be compared to the moisture contents of briquettes made by DoE and WESMA, that

measured less than 6 %.

37

4.1.2.2 The WBT for comparing stoves

For the comparison of stoves, the WBT was performed in the same way as for the fuel testing. The

Firewood and charcoal were only tested on the stove produced for the specific fuel, while the

briquettes were tested on all three stoves. The scheme over the testing is illustrated in table 2.

During the end of the stove testing phase the charcoal stove broke so it had to be replaced. The new

CCS was similar design but 1kg (~20 %) heavier. They were bought from different producers.

PAMET briquettes were used because it seemed like an average briquette concerning size and

burning characteristics. It was also one of the briquettes where a surplus existed.

Firewood stove Charcoal stove 3 stone fire

Briquettes from PAMET X X X

Softwood X - X

Charcoal - X -

Table 2: A table of which fuels where tested on which stove during the stove testing in the MWBT

4.1.3 Results

The results are presented in the table below. This is a summary of all the results gained from the

test. The full table of results is found in appendix 7. Some test has been declared invalid for various

reasons. In a few tests the wind picked up and the losses from the pot were considered too big.

Another reason was that there were too much or not enough water vaporized, this indicates that the

water has not been simmering, respectively it has been boiling too hard. The failed tests are also

documented in appendix 7 but in Italic. The reason why they are made invalid is described in the

bottom of the column.

A general notation when doing the test was that the more compact briquettes did not need the same

tendering. They burned for a longer time without any need to put more fuel into the stove.

38

MWBT Fuels

Fuel Softwood Hardwood Charcoal DoE Ndirande Energy per weight unit (kJ/g) 5,1 3,7 7,3 3,6 3,1

Weight of used fuel (g) 253 366 194 426 456

Time until boiling (min,s) 15.27 12.55 17.42 10.45 14.15

Price per mass unit (MK/kg) 12,70 10,75 32,68 N/A N/A

Price per energy unit (MK/MJ) 2,50 2,93 4,46 N/A N/A

Density (kg/dm3) - - - 0,36 0,30

Number of tests 4 4 6 1 4

Fuel PAMET WESMA MIRTDC Nordins WICO Energy per weight unit (kJ/g) 3,8 3,4 4,9 2,7 5,3

Weight of used fuel (g) 371 376 305 413 282

Time until boiling (min,s) 12.45 12.57 10.51 15.53 11.50

Price per mass unit (MK/kg) 16,96 23,52 N/A N/A 36,90

Price per energy unit (MK/MJ) 4,48 6,99 N/A N/A 6,94

Density (kg/dm3) 0,30 0,40 0,42 0,52 0,40

Number of tests 2 3 4 2 1

Table 3:Results for comparing fuels from WBT

MWBT Stoves

Stove 3SF 3SF FWS FWS CCS CCS Fuel Softwood PAMET Softwood PAMET Charcoal PAMET Energy per weight unit (kJ/g) 3,0 2,5 5,1 3,8 7,3 4,7

Weight of used fuel (g) 448 508 253 371 194 288

Time until boiling (min,s) 12.40 14.32 15.27 12.45 17.42 12.40

Price per mass unit (MK/kg) 12,70 16,96 12,70 16,96 32,68 16,96

Price per energy unit (MK/MJ) 4,25 6,86 2,50 4,48 4,46 3,58

Number of tests 2 2 4 2 6 2

Table 4. Results for comparing stoves from WBT

4.1.4 Sources of Error

It was hard to simulate exactly the same conditions for each test. The most disturbing factor was the

weather conditions. When the testing started it was in the end of the dry season. Warm winds with

dry air are typical for the dry season. The wind made the testing impossible a few times. It increased

the heat transfer to the surrounding environment (losses) and made it hard to keep the water

simmering. This resulted in remarkably low energy values. At the end of the testing period the rain

39

season started with a few rains. The rains probably increased the humidity of the air. Unfortunately

there was no available equipment to measure the humidity.

In the MWBT the stoves should be hot started each time. The definition of hot start was to wait for

no more or less than 10 minutes between the finish of one test and the starting of another. Since the

hot stove was defined by a time parameter more than a certain temperature, it is possible that there

might have been some differences in starting temperatures of the stoves, depending on how much

heat that was conserved from the fire in the preceding test.

The way that the briquettes were burnt in the stoves may have affected the outcome of the tests in

some way. Because of the size differences, it was not possible to burn the large diameter briquettes

(WESMA, PAMET, MIRTDC) in the FWS without first breaking them into smaller pieces. The

size of the combustion chamber was simply too small to fit them inside.

4.1.5 Analysis

4.1.5.1 Fuels

At the production sites visited, the producers never had to pay for the raw materials. The production

costs they have are the handling of the raw materials and the work for pressing. This makes the unit

kJ/g most suitable for the comparison concerning energy, since the costs then mostly depends on

the amount of raw material. These results are shown in Diagram 2.

MWBT Fuels - Results(Best f irst)

0,0 2,0 4,0 6,0 8,0

Nordins

Ndirande

WESMA

DoE

Hardw ood

PAMET

MIRTDC

Sof tw ood

WICO

Charcoal

Energy perweight unit(kJ/g)

Diagram 2: Results from the MWBT for comparing fuels.

40

Sludge? – MIRTDC and PAMET

In the briquettes from MIRTDC and PAMET the same raw material was used, they use plain paper

but add the oily sludge from UniLever. The WESMA briquette has the same shape and density as

MIRTDC. The big difference is the Sludge. According to the test results the sludge seems to

increase the utilized energy of the briquette.

The difference between PAMET and the MIRTDC is the density, which indicates a higher level of

compaction rate. The MIRTDC briquette has the higher level of energy, which indicates that the

higher compaction increases utilized energy. The densities for these briquettes together with the rest

of the briquettes are shown in Diagram 3.


0 0,1 0,2 0,3 0,4 0,5 0,6

Ndirande

PAMET

DoE

WESMA

WICO

MIRTDC

Nordins

Density(kg/dm3)

Diagram 3: The measured densities of the briquettes used in the MWBT

The bad smoke and a smelly briquette is a comment from most of the test with the briquettes that

has the sludge.

Paper or Sawdust? – WICO and WESMA

WICO and WESMA have the same density. WICO is from pure sawdust and WESMA is from

paper. The WICO briquette gets a higher amount of utilized energy from these two. This indicates

that the sawdust has higher calorific value.

41

Pressure and sawdust? – WESMA, Ndirande and DoE

The factors that differentiate the briquettes made by WESMA, Ndirande and DoE from each other

are the density (pressure) and the sawdust content. When looking at the utilized energy for these

three briquettes, the conclusions gained above are confirmed. Higher pressure and sawdust gives

higher utilized energy.

In general it seems like the briquettes makes the water boil faster than both charcoal and firewood,

see diagram 4.


00.00 07.12 14.24 21.36

Charcoal

Nordins

Sof tw ood

Ndirande

WESMA

Hardw ood

PAMET

WICO

MIRTDC

DoE

Time untilboiling(min,s)

Diagram 4: Times needed to bring the water to the local boiling point in the MWBT

Price?

Since most of the briquettes in the test are not sold in the open market it is hard to say anything

about the price. Only the briquettes from WESMA and PAMET can be found in the market. The

prices per kJ for these two are a lot higher than from softwood when consumed in the same stove.

For charcoal the price is the same as for the PAMET briquette, while the price for the WESMA

briquette is still higher. The results are shown in Diagram 5.

42


0 2 4 6 8

Sof tw ood

Hardw ood

Charcoal

PAMET

WICO

WESMA

Price perenergy unit(MK/MJ)

Diagram 5: Calculated prices from the MWBT results for comparing fuels.

4.1.4.2 Stoves

For briquettes (PAMET) it seams that a normal charcoal stove gives the higher energy efficiency

from the three stoves. The 3-stone fire gives bad efficiency for both firewood and briquettes.

Though when comparing with the firewood stove the firewood have 41 % less energy value in the

3-stone fire, while the PAMET briquette has only 35 % less energy value in the 3SF, see Diagram

6. This validates the theory of Richard Stanley that briquettes are less sensitive to the performance

of the specific stove than firewood.

Energy Content

Charc

Division of Energy Systems23747/FULLTEXT01.pdf · number of briquette production sites to study the...

Documents

Transcript of Division of Energy Systems23747/FULLTEXT01.pdf · number of briquette production sites to study the...