1.2 Coordonnées des personnes-ressources et des institutions impliquées dans l'évaluation et la documentation de la Technologie

Nom du projet qui a facilité la documentation/ l'évaluation de la Technologie (si pertinent)

DESIRE (EU-DES!RE)

Nom du ou des institutions qui ont facilité la documentation/ l'évaluation de la Technologie (si pertinent)

University of Botswana (University of Botswana) - Botswana

1.3 Conditions relatives à l'utilisation par WOCAT des données documentées

Quand les données ont-elles été compilées (sur le terrain)?

19/02/2009

Le compilateur et la(les) personne(s) ressource(s) acceptent les conditions relatives à l'utilisation par WOCAT des données documentées:

Oui

2.1 Courte description de la Technologie

Définition de la Technologie:

Production of methane gas from cow-dung for use in house-hold cooking, heating and lighting in order to reduce fire wood demand

2.2 Description détaillée de la Technologie

Description:

Biogas plant: The biogas plant can be constructed in several ways as long as it can provide a medium for the biological material be digested. Biogas is the name given to the gas that is produced during the decomposition of some organic waste specifically to produce methane gas. The gas is then captured in a storage tank (on site) to be used for household energy needs. In many parts of the world where this technology is used (including Botswana) the most common form of input material is cow dung making it more appropriate for rural environments.

Purpose of the Technology: Advantages: the technology offers two major advantages; first, at every level of use i.e. individual or institutional, savings in terms of energy is realized. The only costs that are borne are at installation, otherwise input of cow dung has a minimal cost of collection (if any at all). The second advantage is that there is reduced usage of fuel wood which translates into less cutting down of trees leading to reduced deforestation and degradation of land. A disadvantage is the initial investment which is significant for poor farmers.

Establishment / maintenance activities and inputs: Construction of the biogas plant: construction of the plant consists of three main chambers: namely, the Digester pit where all the microbiological reactions or decomposition of the material takes place. The digester has to be built to be air-tight with the released gas only escaping into the gas holder. The gas holder is connected to the digester by way of a pipe. Its main purpose is to collect all the gas that has been fermented. The mixing pit is the input chamber where the dung is mixed with water and fed into the digester. The amount and quality of water required for this is no constraint, even in this water stressed area. Construction the biogas plant has to be done according to specifications. A technical drawing of the plant is shown on page 3. The purpose of the technology is to use it for house-hold energy (for cooking, lighting and running appliances).

Natural / human environment: In Botswana the technology was introduced by the Rural Industries Innovation Center which is a government funded research institution. Despite the existence of this company for many years, the uptake has been very low due to poor marketing and extension services and lack of financial assistance to poor farmers.
Biogas is suitable either for a farm, cattle post or rural setting where the inputs (cow dung) are easily available. But there are possibilities of experimenting with other bio-degradable materials in major centres where cow dung is not readily available.

2.3 Photos de la Technologie

2.5 Pays/ région/ lieux où la Technologie a été appliquée et qui sont couverts par cette évaluation

2.6 Date de mise en œuvre de la Technologie

Si l'année précise est inconnue, indiquez la date approximative: :

• il y a entre 10-50 ans

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• par le biais de projets/ d'interventions extérieures

Commentaires (type de projet, etc.) :

The technology is promoted by a government funded NGO, but has its origins outside the country

3.1 Principal(aux) objectif(s) de la Technologie

• réduire, prévenir, restaurer les terres dégradées
• préserver l'écosystème
• créer un impact économique positif

3.2 Type(s) actuel(s) d'utilisation des terres, là où la Technologie est appliquée

Commentaires:

Major land use problems (compiler’s opinion): Overgrazing of the commons, droughts, saline water and over-harvesting of fuelwood for cooking, heating leading to deforestation and land degradation

Major land use problems (land users’ perception): Overgrazing of the commons, droughts, saline water and over-harvesting of fuelwood for cooking, heating leading to deforestation and land degradation.

Grazingland comments: Biogass technology is not applied in the Boteti area at the moment, only at DESIRE test site.

Selective felling of (semi-) natural forests: specific tree species are felled for fuelwood even though people are supposed to take only fallen-dead wood

Type of cropping system and major crops comments: Mixed cropping is the traditional practice but government extension advice promotes monocropping which the majority find expensive and risky.

Type of grazing system comments: Biogass technology is not applied in the Boteti area at the moment, only at DESIRE test site.

Constraints of settlement / urban

3.3 Informations complémentaires sur l'utilisation des terres

Approvisionnement en eau des terres sur lesquelles est appliquée la Technologie:

• pluvial

Commentaires:

Water supply: Also post-flooding

Nombre de période de croissance par an: :

• 1

Précisez:

Longest growing period in days: 179 Longest growing period from month to month: Oct - Mar

Densité d'élevage/ chargement (si pertinent):

1-10 LU /km2

3.4 Groupe de GDT auquel appartient la Technologie

• technologies d'efficacité énergétique

3.5 Diffusion de la Technologie

Commentaires:

Total area covered by the SLM Technology is 0 m2.

This technology is basically on a point location, even though it is to benefit a wider area in terms of conservation

3.6 Mesures de GDT constituant la Technologie

Commentaires:

Main measures: management measures

3.7 Principaux types de dégradation des terres traités par la Technologie

Commentaires:

Main type of degradation addressed: Bc: reduction of vegetation cover, Bs: quality and species composition /diversity decline

Main causes of degradation: deforestation / removal of natural vegetation (incl. forest fires) (harvesting of fuelwood for cooking, sometimes live trees are harvested.), land tenure (Area is communal grazing land)

Secondary causes of degradation: over-exploitation of vegetation for domestic use (Trees are cut for bush fences), droughts (The study area is prone to droughts), poverty / wealth ((lack of alternative livelihood sources))

3.8 Prévention, réduction de la dégradation ou réhabilitation des terres dégradées

Spécifiez l'objectif de la Technologie au regard de la dégradation des terres:

• restaurer/ réhabiliter des terres sévèrement dégradées

Commentaires:

Secondary goals: prevention of land degradation, mitigation / reduction of land degradation

4.1 Dessin technique de la Technologie

4.2 Spécification/ explications techniques du dessin technique

The diagram shows the technical layout of a biogas plant; showing the position of the main components: Digester, Gas holder, Mixing pit, and outlet. Cow dung & or kitchen waste (except bones) is mixed with water to form a sludge. This sludge is fed into the digester pit where decomposition and fermentation takes place. As the sludge ferments, methane gas is produced. Methane is a combustible gas and can therefore be used for cooking and lighting. Specially designed gas stoves and lanterns may be required as the gas would not be purified and hence ‚thicker‘ than commercially produced gasses. However, the design can include a water filled pipe bend (u shaped) between the gas holder and outlet pipe. The water in this pipe would help to purify the gas before it is fed to the household appliances. The gas holder tank floats in water, through which the gas bubbles escape and methane gas collects into the floating tank. An outlet through which decomposed material leaves the plant is necessary. Old sludge would float and be removed through this opening (Diagram drawn by G. Koorutwe, Department of Environmental Science, University of Botswana).

Location: Mopipi. Boteti Sub-District

Date: 05/10/11 (revised)

Technical knowledge required for field staff / advisors: high (Skilled technician is needed for installation)

Technical knowledge required for land users: moderate

Main technical functions: reduction of wood exploitation

Secondary technical functions: promotion of vegetation species and varieties (quality, eg palatable fodder), enhancement of tree growth

Structural measure: Digestion pit
Depth of ditches/pits/dams (m): 3.38
Width of ditches/pits/dams (m): 2.06

Structural measure: Gas holder
Depth of ditches/pits/dams (m): 2
Width of ditches/pits/dams (m): 1.6

Construction material (other): bricks, pipes, cement, iron sheets

Change of land use practices / intensity level: Use of biogass for cooking would lead to reduced cutting of wood for cooking

4.3 Informations générales sur le calcul des intrants et des coûts

autre/ monnaie nationale (précisez):

Pula

Indiquer le taux de change du dollars en monnaie locale (si pertinent): 1 USD= :

6,5

4.4 Activités de mise en place/ d'établissement

	Activité	Type de mesures	Calendrier
1.	Construction	Modes de gestion	N/A

4.5 Coûts et intrants nécessaires à la mise en place

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% des coût supporté par les exploitants des terres
Main d'œuvre	Labour	Tank	1,0	198,0	198,0	100,0
Equipements	Tank	Tank	1,0	615,0	615,0	100,0
Equipements	Bricks	Tank	1,0	77,0	77,0	100,0
Equipements	Cement	Tank	1,0	123,0	123,0	100,0
Equipements	Plumbing material	Tank	1,0	154,0	154,0	100,0
Matériaux de construction	Earth	Tank	1,0	31,0	31,0	100,0
Coût total de mise en place de la Technologie					1198,0

Commentaires:

Duration of establishment phase: 0.5 month(s)

4.6 Activités d'entretien/ récurrentes

	Activité	Type de mesures	Calendrier/ fréquence
1.	Filling up with cow dung and water	Modes de gestion	1 Day

4.7 Coûts et intrants nécessaires aux activités d'entretien/ récurrentes (par an)

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% des coût supporté par les exploitants des terres
Equipements	Cow dung	Tank	1,0	33,0	33,0	100,0
Coût total d'entretien de la Technologie					33,0

Commentaires:

Costs were calculated for labour and material based on the real cost of construction at the Mopipi Site.

4.8 Facteurs les plus importants affectant les coûts

Décrivez les facteurs les plus importants affectant les coûts :

Material, labour and equipment used in construction are the most determining factors affecting the costs (installation cost is US$ 1198).

5.1 Climat

5.2 Topographie

Commentaires et précisions supplémentaires sur la topographie:

Altitudinal zone: 501-1000 m a.s.l. (Part of the Makgadikgadi basin)
Slopes on average: Flat (ranked 1, mainly low lying land of lucrustrine (pans) formation) and gentle (ranked 2, gently sloping (plains))

5.3 Sols

Si disponible, joignez une description complète du sol ou précisez les informations disponibles, par ex., type de sol, pH/ acidité du sol, capacité d'échange cationique, azote, salinité, etc.

Soil depth on average: Shallow (ranked 1, generally soils are 40cm deep, underneath is a calcrete layer at about 40cm deep) and deep (ranked 2, some sandy area away from pans e.g. the Gidikwe Ridge )
Soil texture: Coarse/light (ranked 1, away from pans/river/flood plain = main soil type) and fine/heavy (ranked 2, sticky when wet in the depression)
Soil fertility: Low (ranked 1, sandy areas (Arenosols)) and medium (ranked 2, in flood plains of the Boteti river)
Topsoil organic matter: Low (ranked 1, low on sandy areas/soils) and topsoil organic matter (ranked 2, on the flood plains for molapo farming)
Soil drainage/infiltration: Good (ranked 1, very good on sandy soils) and medium (ranked 2, flood plains are medium)
Soil water storage capacity: Very low (ranked 1, on sandy soils) and medium (ranked 2, on flood plains)

5.4 Disponibilité et qualité de l'eau

Commentaires et précisions supplémentaires sur la qualité et la quantité d'eau:

Ground water table: >50m (ranked 1, for Boreholes) and 5-50 m (ranked 2, wells in the Boteti River bed)
Availability of surface water: poor/none (dry season-unreliable river flow/rainfall)
Water quality (untreated): Poor drinking water (treatement required, salty water in most areas, ranked 1) and unusable (sometimes too salty even for livestock consumption, ranked 2)

5.5 Biodiversité

Commentaires et précisions supplémentaires sur la biodiversité:

Biodiversity: High (several game reserves (protected areas) nearby, ranked 1) and low (grazing areas with arable agriculture, ranked 2)

5.6 Caractéristiques des exploitants des terres appliquant la Technologie

Indiquez toute autre caractéristique pertinente des exploitants des terres:

Land users applying the Technology are mainly Leaders / privileged
Difference in the involvement of women and men: There is no difference, as this is mainly a family thing or institutioanal like in schools and community halls
Population density: < 10 persons/km2
Annual population growth: 2% - 3%
10% of the land users are very rich and own 50% of the land (Cattle farmers).
60% of the land users are average wealthy and own 30% of the land (Most inhabitants).
30% of the land users are poor and own 20% of the land (Subsistance farm).
Off-farm income specification: Saves money for buying commercial gas and electric power. Helps conserve the forests. Limited off-farm income opportunities for everyone including non-adopters of the technology.
Level of mechanization: Animal traction (mostly donkeys for draught power)
Market orientation of annual cropping production system: Mixed (subsistence/commercial) Could be used/produced for domestic and commercial purposes.
Market orientation of grazing land production system: Subsistence and commercial/market
Market orientation of forest production system: Mixed (subsistence/commercial) in both cases use of biogas is approppriate

5.7 Superficie moyenne des terres détenues ou louées par les exploitants appliquant la Technologie

5.8 Propriété foncière, droits d’utilisation des terres et de l'eau

Propriété foncière:

• communauté/ village
• individu, sans titre de propriété

Droits d’utilisation des terres:

• accès libre (non organisé)
• individuel

Droits d’utilisation de l’eau:

• communautaire (organisé)
• individuel

Commentaires:

The SLM can be used by anybody - not specified to any group. Dual grazing rights is a problem (private ranchers can also use the commons).

5.9 Accès aux services et aux infrastructures

6.1 Impacts sur site que la Technologie a montrés

Impacts socio-économiques

Production

Revenus et coûts

Impacts socioculturels

Impacts écologiques

Cycle de l'eau/ ruissellement

Sols

Biodiversité: végétale, animale

Réduction des risques de catastrophe et des risques climatiques

Autres impacts écologiques

6.2 Impacts hors site que la Technologie a montrés

6.3 Exposition et sensibilité de la Technologie aux changements progressifs et aux évènements extrêmes/catastrophes liés au climat (telles que perçues par les exploitants des terres)

Changements climatiques progressifs

Changements climatiques progressifs

	Saison	Type de changements/ extrêmes climatiques	Comment la Technologie fait-elle face à cela?
températures annuelles		augmente	bien

Extrêmes climatiques (catastrophes)

Catastrophes météorologiques

	Comment la Technologie fait-elle face à cela?
pluie torrentielle locale	bien
tempête de vent locale	bien

Catastrophes climatiques

	Comment la Technologie fait-elle face à cela?
sécheresse	bien

Catastrophes hydrologiques

	Comment la Technologie fait-elle face à cela?
inondation générale (rivière)	bien

Autres conséquences liées au climat

Autres conséquences liées au climat

	Comment la Technologie fait-elle face à cela?
réduction de la période de croissance	bien
temperature decrease	pas bien

Commentaires:

Biogas technology may be limited under extreme cold conditions whereby fermentation may be limited by cold temperatures.

6.4 Analyse coûts-bénéfices

Quels sont les bénéfices comparativement aux coûts de mise en place (du point de vue des exploitants des terres)?

Quels sont les bénéfices comparativement aux coûts d'entretien récurrents (du point de vue des exploitants des terres)?

Commentaires:

Very costly to set up, if no government aid. It is however very good for long term water provision.

6.5 Adoption de la Technologie

Si disponible, quantifiez (nombre de ménages et/ou superficie couverte):

10

Commentaires:

1% of land user families have adopted the Technology with external material support

10 land user families have adopted the Technology with external material support

Comments on acceptance with external material support: A very insignificant number of individual farmers have used this technology

Comments on spontaneous adoption: The technology has mostly been used where the Research institution has installed in farmers' properties. Only in very few instances around the country have individuals installed it for themselves.

There is a little trend towards spontaneous adoption of the Technology

Comments on adoption trend: There seems to be very little marketing of biogas in the country

6.7 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue de l'exploitant des terres
Problems of diminishing firewood species are reduced. How can they be sustained / enhanced? Because it is not every or all species that is used for firewood, the targeted species are quickly diminished
Cost of getting firewood is reduced How can they be sustained / enhanced? Distance to wood collection places are ever increasing hence users have to buy from truck or donkey cart owners
More time is freed How can they be sustained / enhanced? This especially applies to children (of school going age) in that they would have more time for their home works.

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé
Low maintenance and inputs are required for this technology How can they be sustained / enhanced? There is need for promotion of the technology
The structures to be put in place are very basic How can they be sustained / enhanced? There is need for the government to subsidize farmers in installing biogas plants, especially in the rual areas.
Good for rural households where firewood is used extensively. How can they be sustained / enhanced? Improve income of rural families so that they could afford the technology

6.8 Faiblesses/ inconvénients/ risques de la Technologie et moyens de les surmonter

Faiblesses/ inconvénients/ risques du point de vue de l’exploitant des terres	Comment peuvent-ils être surmontés?
Too expensive for poor farmers to adopt without assistance	Donor/government subsidies

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Brown, V. J., 2006. BIOGAS: A Bright Idea for Africa. Environ Health Perspectives. 114(5), pp. A300–A303.

Disponible à partir d'où? Coût?

internet

Titre, auteur, année, ISBN:

Dayal, M., Vimal, O.P., Singh, K.K., 1989. Biomass gasification in India — DNES activities. Biomass, Volume 18, issues 3-4,pp. 197-204

Disponible à partir d'où? Coût?

http://www.ganesha.co.uk/Articles/Biogas%20Technology%20in%20India.htm