6 - co2 neutral energy (7 of 8)

8/14/2019 6 - CO2 Neutral Energy (7 of 8)

1/14


2/14

40 Green World Actions112

One way to reducethe problem of de-forestation is by cul-

tivating a mixtureof plants that alsoproduce firewood.This can be done byimproved fallowing,

where the produc-tion of firewood iscombined with thecultivation of onesown fertilizer (see

section 21).Another way to reduce carbon emissionsis to choose alternatives that reduce theuse of firewood. Among these are forexample:

constructing firewood-saving stoves producing and using briquettes made

from available organic matter using biogas systems, which produce

cooking gas from manure and organicwaste

using solar stoves, in which the food isprepared using solar energy

There are other renewable energy systemsthat require more technological knowledge.Some of these can, however, also be used

to supply energy to rural communities inAfrica while simultaneously reducing carbondioxide emissions.For example: producing jatropha oil and using it as

lamp oil, as biofuel in stationary dieselengines or in adapted diesel engines or- after transformation - as biodiesel

utilising solar panel systems to produceelectrical energy

utilising residues from agricultural in-dustries for producing energy - such assugar cane bagasse or coconut shellsfor the production of charcoal bri-quettes

utilising biomass - from trees with highenergy values or agricultural residues- in gasification systems, where the gasproduced may be used mixed with die-sel on a conventional generator. Thesesystems are marketed in India and used,

for example, to generate electricityfrom rice husk. There are also small-scale gasification systems - for exampleto supply energy to irrigation pumps.

This stove

uses 30%less en-

ergy than

a con-

ventional

3-stone

fire


3/14

43 - Energy - Firewood-Saving Stove 113

43 Firewood-

Saving StoveAdvantages of this stove

A well-built stove can use as little ashalf the firewood used by a traditional3-stone fire.

By using a firewood-saving stove, peoplewho usually purchase firewood will savemoney, while people who usually collect

firewood will save time. This stove has positive environmentalimpacts, by protecting trees and savingwood.

This stove reduces the amount of smokein the kitchen, and thus improves thehealth of the people who cook. Inhalingsmoke from a stove is as unhealthy assmoking cigarettes.

This stove reduces the likelihood thatchildren and others will burn them-

selves. This stove improves hygiene in the

kitchen. Pots used on the stove are

easier to clean than those used on anopen fire.

This stove is easy to build, and it is madefrom material available anywhere.

How to make a firewood-saving

stove

Step 1 - Collect the material

You need clay, sand, seven large bricksand water.

The best clay to use is that from smallanthills found in wet areas (dambos).

Clay from termite hills can also beused.

Where anthill clay is not available, it maybe necessary to dig deeper to find good

clay.

Remove stones, sticks,and other foreign mate-rial from the clay and

sand.

Step 2 - Prepare the ma-

terial

Crush the clay into

dust. Soak it in water overnight. Mix the sand and clay together using

a ratio of one quantity of sand to twoquantities of clay.

Add water until the mixture is easy towork with. To check if the mixture isgood, make a ball and drop it on theground. If it splashes out, the mixtureis too wet, if it falls to pieces, it is too

dry.

Step 3 - Foundation

Decide where to placethe stove. If it is placedin an indoor kitchen, it

must face the door inorder to get enough airfor appropriate com-bustion. If the stove is placed outside,

the opening must face the directionfrom which the wind usually blows.

Position 4 large (15 cm x 20 cm) claybricks so that they forma square.

Fill the hole in the mid-

dle halfway up withclay and plaster thebricks outside and ontop with clay/sand mix-

ture.

Step 4 - Heat insulation

Place ash to a depth of 5cm into the hole between the bricks andcover it with the clay mixture. The ash acts

as a heat insulator so that heat from the fire

Mix sand

and clay

- 1:2

4 bricks

form the

foundation

Use clay

from ant-

hills


4/14


does not penetrate into theground.

Step 5 - Construction Use a 5 litre paint or oiltin - or a cooking pot - asa mould. The tin should be17-20 cm in diameter. Place

the tin in the middle of theconstructed foundation, ontop of the ash insulationlayer. Place the clay-sand mix-

ture around the tin until itis 4 cm from the top of thetin. This should make thefirebox 19 - 20 cm high. Itis important not to make

the walls too thick. Oth-erwise, they absorb toomuch heat.

Step 6 - Make the fire-

wood rest

Lay three bricks as afoundation, as shown inthe photo. Plaster the bricks with the

clay-sand mixture. Leave the stove to restovernight.

Step 7 - Shape the stove

Remove the tin.

Shape the outside of thestove using a knife or con-struction trowel. Make the stove smooth

using water.

Step 8 - Carve out the

firewood opening

Carve out an opening forthe firewood using a knife

or building trowel. The size

should beabout 12 x17 cm. Do

not make ittoo small,otherwisey o u w i l ln e e d t o

chop thef i rewoodtoo much. Make sure the stove wall above the holeis not too narrow. It should be 5 cm high

or more in order not to break easily.

Step 9 - Carve the edge

Carve the edge of the top opening to anangle of 45 with a knife. This will make

it possible to place pot-rests and usepots of different sizes (see the photoshowing pot rests).

Step 10 - The pot rest

Use some clay to make a pot-rest. It

should be about three fingers wide andone finger thick (5 cm x 1 cm). It is im-portant not to place a pot-rest on topof the firewood opening.

Make small cuts on the pot-rest andon the part of the stove where it isto be placed (so that they fit togetherfirmly).

Add some water to both surfaces Press the pot rest firmly against the

stove and shape it nicely. See next photoshowing pot rests.

Step 11 - Place the pot rests

Place three pot-rests on the stove, asshown in the photo. (It is importantto have three of them - not any othernumber).

The pot-rests allow smoke to come out,and enable the use of pots of different

diameter.


5/14


6/14


44 Jatropha for

Fences and OilJatropha

Jatropha cur-

cas is a smalltree or largeshrub whichcan grow to aheight of up to

5 metres andlive for morethan 50 years.It is a drought-

resistant spe-cies widely cul-

tivated in the tropics as a hedge to protectfields and gardens, since animals do not eatit. The leaves and seeds are toxic to humansand many animals.

Propagation from seeds

The best timefor direct seed-

ing is the be-ginning of therainy season.After the firstrains, when thesoil is wet, theseeds are sown

to a depth of2-3 cm. Theseeds sprout

faster if the part from where the roots willemerge (indicated by small spots on theseed) faces downwards. After 2 years, or3 rainy seasons, the jatropha plant will startto produce seeds.

Propagation by cuttings

Jatropha is easily propagated from cuttings.These should be more than one year old,

lignified (this means the cuttings shouldbe woody, not green branches) and about60-120 cm long. The best planting time is1-2 months before the beginning of the rainyseason. For hedging, the cuttings can be

planted alongside one another, like a regu-lar wooden fence. The cuttings should beplaced 20 cm into the soil, and held in placewith horizontal branches on top. They willthus function as fencing immediately. Within

a few weeks, the cuttings will start to grow.Cuttings can easily be kept in a shaded placefor a few weeks, without drying out.To get an efficient live fence that protectsgardens against animals, the distance be-

tween the plants should be 5 cm. Deadplants should be replaced by new cuttingsor seeds.It is also possible to make a double row,with 20 cm distance between the two rows.The distance between each plant in the row

should be 10-15 cm. Since the young plantshave not developed their repellent odour,they are at risk of being eaten by animals.Therefore, they must be protected with

some tree branches during the first year.After the rainy season, the plants will belarge enough to function as a protectivefence. If well maintained, this kind of hedgecan even keep chickens out of gardens.

Possible uses of jatropha

The plant is often used, in small quanti-ties, as a plant medicine.

It is used to mark boundaries and as livefencing.

The fences are useful against erosion

- especially if combined with vetivercontours or stone bunds - lines ofstones running along contours.

Jatropha

fruits.

Seeds con-

tain up to

35% oil

Jatrophas

can form

a closed

fence

within 2

years


7/14

44 - Energy - Jatropha for Fences and Oil 117

Oil which can be used for making soapor lamp fuel can be pressed from theseeds, or the seeds can be sold directly

for industrial uses.

Jatropha for oil production

The suitability of jatropha for oil productionvaries according to the variety of jatrophabeing used, and ranges from 300 g to 9 kgper tree per year. This corresponds to

- 2 tons of oil per hectare.The seeds contain about one-third oil. With

a manual press, around two-thirds of this oilcan be extracted (5 kg of seeds give aboutone litre of oil).

Jatropha press cake (the material that isleft after pressing the oil) is valuable as anorganic manure. It is comparable to chickenmanure in terms of its effectiveness. Oneton of jatropha press cake corresponds to

200 kg of chemical fertiliser.Because the press cake still contains someoil, it also has pesticidal properties, and

may reduce the amount of nematodes (acommon pest) in the soil.The most interesting and economicallyviable use of the jatropha oil is for soapproduction.

Jatropha gives a good quality, glycerine-rich soap which has positive effects on the

skin.Jatropha oil can be used as lamp oil, althougha kerosene lamp requires conversion to

burn jatropha, because jatropha oil is heavi-er than kerosene). A floating wick in a glasswith oil can also be used, as developed byBinga Trees Trust. The use of jatropha oilas a lamp oil is explained further below.

Oil extraction

Seed preparation

Seeds for oil extraction should be dried

in sunlight on top of a black plastic sheet

for several hours,or in a roasting panfor 10 minutes. It is

important that theseeds are heated, butnot burnt. This proc-ess breaks down thecells that contain the

oil, allowing the oil toflow out more easily.Heat also thins theoil, which improvesthe extraction proc-

ess.

The manual press

Many villages havemanual presses for the production of sun-

flower or sesame oil. These can also be usedto press jatropha seeds. In such presses, apiston creates pressure to force the oil outof the press cake. Sometimes the pistongets stuck and is difficult to move. Then thepress has to be taken apart and the piston

and its cylinder need to be cleaned thor-oughly. It is possible to regulate the outletof the manual press. The more closed itis, the more difficult it becomes to press

the cake through the gap. Thus, more oilis extracted (a higher extraction rate). Theoutlet should be regulated in such a waythat one person can push down the leverwithout forcing too much (no hanging onthe lever).

Oil purification

Sedimentation

Letting the sediments settle at the bottomis the easiest way to obtain a clear oil. It isbest to use several containers, so that the

clear oil is siphoned from one containerto the next. After 24 hours this process isrepeated at least one more time to get a

batch of clear oil.

Manual

press to

produce

oil from

seeds


8/14


The oil left in the containers with thesediments (remains of seed shells, etc.) willeventually also separate.

Boiling with water

The purification process can be greatly ac-celerated by boiling oil and water togetherin a ratio of four parts oil to one part water.

The boiling should continue until the waterhas evaporated (there are no bubbles ofwater vapour anymore). After a few hours,the oil becomes clear.

FilteringPassing the raw oil through a filter is avery slow process and has no advantage interms of sedimentation. Therefore, it is notrecommended.

Cleaning the press

Because jatropha oil is not suitable forconsumption, the manual press must becleaned thoroughly after being used to press

jatropha and before it is used to extract

cooking oil. At least one kg of edible seedsmust be pressed, and the oil thrown away

or used as biofuel.before the press can

be used for edibleoils again.

Lamp oil

Lighting is a basic

need and kerosene isnot always availablein rural areas. Manypeople then use die-

sel instead. This creates much smoke, has adisagreeable smell and is unhealthy.

Two lamp designs using jatropha oil havebeen developed.

Adapted kerosene lamp

To use a kerosene lamp for burning jatrophaoil, the body the lamp is modified so that themechanism for moving the wick is turned

around to reduce the height between thesurface of the oil and the flame. This isnecessary because jatropha oil is heavierthan kerosene. This design is promoted byAfricare in Lusaka.

Binga Oil Lamp

A very simple and suitable design for a jat-ropha oil lamp was developed by the Binga

Trees Trust, at Kariba Lake in Zimbabwe.This model works very well and can easilybe assembled.It uses a small glass filled with oil up to 3- 5 cm below the rim. A small cork disc (ora disc of a maize cob) floats on top of theoil, wrapped in aluminium foil to prevent itfrom burning. A hole in the centre of thedisc contains a cotton wick. The floatingwick holder is centred using match sticks.

Thus, the flame of the oil lamp is only some1 or 2 mm above the surface of the oil andgives a quiet and steady light. There is someevidence that the smell of this light alsorepels mosquitoes.

An even simpler system consists of takingsome cotton and twisting it into a form likean inverted mushroom. This is then placedhead down in a plate or glass with a littleoil and the end of the cotton is lighted as

a wick.

Information from the manual The Jatropha

System published by GTZ. More information

at: www.jatropha.deThe Binga

Lamp


9/14

45 - Energy - Fuel Briquettes 119

45 Fuel

BriquettesIntroduction

A briquette is a block of compressed ma-terials suitable for burning. Briquettes canbe made from materials that cost little or

no money to obtain, such as old newspaperor partially decomposed plant waste. Theycan be used as fuel instead of charcoal, fire-

wood or mineral coal, and may cost less.Depending on which materials were used tomake the briquettes, they may burn cleanerthan charcoal. Finally, turning waste materi-als into a fuel source is attractive becauseit reduces waste as well as reducing thedemand for non-renewable fuel resources.

Many different methods and technologiesexist for pressing briquettes. Each has itsown unique advantages and disadvantages.This document describes two designs for

briquette presses that are used by the or-ganisations ECHO and WWF-Malawi.

Materials used for briquettes

One of the most commonly used materialsfor making briquettes is shredded news-paper. Small woodchips and sawdust alsowork well. Plant waste can make good bri-

quettes, but it is best to compost the plant

waste for a while (two or three weeks) sothat it will stick together when it is pressed.Adding a small amount of wood ash to themix makes briquettes harder and makesthem burn longer. The addition of manurecan achieve the same effect.

Testing materials for briquettes

To test a material to see whether it will

make good briquettes, first soak the mate-rial in water.Take a handful of material and press it intoa ball. If the ball retains its shape and doesnot fall apart, it will most likely press into agood, solid briquette. If the ball falls apart,

you should add materials that increase thebinding capacity of the mixture.

Binding materials

Examples of good binding materials are fishwaste, molasses, wood ash, manure, maizeor wheat flour. If the press functions well,most mixtures for briquettes will not needbinding materials.

Recipe for a good briquette

A good briquette is one that burns for a longtime. Make mixtures with locally available

materials, and experiment with the pro-portions in order to come up with a goodbriquette recipe. For example, although itis possible to make briquettes with onlyshredded newspaper, they will burn betterif you add some small woodchips or a verysmall amount of charcoal dust.After the briquettes are pressed, they willstill be moist. It is important to dry themfully before using them as fuel. Drying for

a few days in the sun should be enough.Before using them as fuel, the briquettesshould be broken into smaller pieces inorder to increase the surface area, whichwill make them burn more efficiently.


10/14


11/14

45 - Energy - Briquettes for fuel 121

Wooden briquette press

This press is primarily made of wood andmaterials that are easy to find. Pressure is

achieved through a simple lever mechanism.

Two people are needed for the press towork efficiently.

Press dimensions (see large photo):A: 215 cm (86 inches)B: 80 cm (32 inches)C: 85 cm (34 inches)

D: 180 cm (72 inches)

Details of the pressure-generating mecha-

nismA: 30 cm (12 inches)B: 30 cm (12 inches)

The mould for the briquettes is made from

a piece of PVC pipe 40 cm (16 in) long witha 7.5 cm (3 in) diameter. Holes should bedrilled all around the pipe, so that water canescape when the briquette is pressed.

Use a sturdy, flat piece of wood as a supportagainst which the mould will be pressed (seeillustration). On top of the support, placea wooden disc about 3 cm in height with adiameter slightly smaller than the diameterof the PVC pipe. Screw it down onto the

flat wooden base. The PVC pipe can then beplaced on the wooden disc and will not slidewhen pressureis applied from

the press.Another pieceof PVC pipewith a smallerdiameter canbe u sed t o

form a hole inthe centre ofthe briquette(see illustra-

Wooden

press. De-

tails of the

pressure-

generating

mecha-

nismbelow


12/14


PVC pipe

with holes

that allow

the water

to escape

Ready

to press

some bri-

quettes

A wooden

structure

facilitates

briquette

extraction

tion). To place the new pipe in the rightposition, partially drill a hole into the baseboard with the same diameter as the small

pipe so that it canbe inserted into thehole. This will helpkeep it in the middleof the mould when

you fill it with yourbriquette material.Though this hole isnot needed, it hasbeen found that bri-

quettes dry fasterwhen there is a cen-tral hole.

Briquette extraction

Briquette removal may be aided by a smallwooden frame which is built and designedso that the briquette mould rests on its

edges. The structure is pressed once moreto force the briquettes out through thebottom of the mould.

Information and photos of the wooden press

from publication Briquettes Presses by J.

Dahlman and C. Frost at the ECHO

website: www. echonet.org

Information and photos of the Malawian pro-

duction from the WWF website:

www.panda.org


13/14

46 - Energy - Solar Cooking Panel 123

46 Solar

Cooking PanelCookit - The foldable family

panel

The foldable family cooking panel is nei-ther a solar oven or a curved concentra-tor but a great hybrid. Its utter simplicitybelies its powerful cooking power. Its lowcost means it is possible to give large num-

bers of people access to solar cooking. Itcan be used for cooking food, baking bread,pasteurizing water and teaching the basicsof solar energy.

The developers of Cookit are Roger Ber-nard (France) and Barbara Kerr (the USA),who also worked with Edwin Pejack, JayCampbell, and Bev Blum from Solar Cook-ers International. Extensive field tests in theUSA, as well as those with refugees in Kenyaconfirm its performance, convenience, low

cost, acceptance and adaptability to diverseneeds.

Construction drafts:

Start with a big piece of cardboard about

1m x 1.33m (3x 4). Cut and fold as shown.The angles and folds shown are best, butsmall variations can be made. Hint: To makeclean straight folds in cardboard, first make

a crease along the line with a blunt edgesuch as a spoon handle, then fold against afirm straight edge. Make the slots a little toosmall and narrow so that they fit snugly tohold up the front panel. Glue aluminium foilon the side that will form the inside surfaces

when the oven is set up for cooking. To setup, lay panel flat with shiny side up. Fold upfront and back parts and fit back cornersinto the slots in front. Youre ready to cook!

Put your food into a dark-coloured pot.

Then place the potinside a plastic bag(Oven cooking bags

of special plastic willwithstand the heatbest. A normal clearbag can also be usedbut will not last long).

Close the open endof the bag and placepot and bag into thecentre of the solarcooker.

You will have to ex-perience to find outhow long time is needed to cook the food.The cooker works best in direct sunlight,

and should be turned at least every hourto catch as much heat as possible.

Hints

Dr. Steven Jones found that raising the pot

on a wire frame improved cooking in a panelcooker.

Information and

d r aw i n g s b y

Solar Cookers

International,

www.solarcook-

ing.org/cookit.

htm

Solar

cardboard

cooker in

Zimbabwe


14/14


Solar panel dimensions. It can be assembled from several pieces of cardboard

6 - co2 neutral energy (7 of 8)

Documents