Desire for Greener Land

Human Environment
Mixed land per household
(ha)
10,000
Land user: individual privileged large scale
land users
Population density: < 10 persons/km 2
Annual population growth: 2% - 3%
Land ownership: communal / village
Land use rights: open access (unorganised)
(The SLM can be used by anybody - not
specified to any group. Dual grazing rights are
a problem because private ranchers can also
use the commons).
Water use rights: communal (organised) (The
SLM can be used by anybody - not specified to
any group).
Relative level of wealth: very rich, which
represent 10% of land users; 50% of the total
land area is owned by very rich land users
Implementation activities, inputs and costs
Establishment activities
1. Construction
Maintenance/recurrent activities
1. Filling up with cow dung and water
SLM Technology: Biogas, Botswana DESIRE – WOCAT 2012
Importance of off-farm income: less than 10% of all
income: Saves money for buying commercial gas and
electric power. Helps conserve the forests. Limited offfarm
income opportunities for everyone including nonadopters
of the technology.
Access to service and infrastructure: low: technical
assistance, employment, market, energy, financial
services; moderate: health, education, roads & transport,
drinking water and sanitation
Market orientation: mixed (subsistence and commercial)
Technical drawing
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).
Establishment inputs and costs per unit
Inputs Costs (US$) % met by
land user
Labour 198 100
Equipment
- tank
- bricks
- cement
- plumbing material
Construction material
- earth
615
77
123
154
100
100
100
100
31 100
TOTAL 1198 100
Maintenance/recurrent inputs and costs per unit per year
Inputs
Construction material
Costs (US$) % met by
land user
- cow dung
33 100
TOTAL 33 100
Remarks: Material, labour and equipment used in construction are the most determining factors affecting the costs (installation cost is
US$ 1198). Costs were calculated for labour and material based on the real cost of construction at the Mopipi Site. The local wage rate is
1 US$/day. Each biogas unit is beneficial to one household, so it serves on average 6 persons.
195