2.1.2. Biogas
Domestic biogas systems convert animal manure and human excrement at
household level into small, but valuable, amounts of combustible methane gas.
This ‘biogas’ can be effectively used in simple gas stoves for cooking and in lamps
for lighting. The plant consists of a digester to mix and store the ingredients and a
Figure 1: A typical biogas plant: SNV
container for the resulting
biogas. At least two cattle or
six pigs are required to
produce enough biogas to
meet a household’s basic
cooking and lighting needs.
Investment costs of quality
biogas plants vary between
EUR 200 and 900, depending
on plant size, location of
construction and country. 8
Use of biogas saves time on cooking processes and firewood collection. Biogas
burns very efficiently, without producing smoke or soot; reducing resulting
respiratory and eye problems. The residue of the process, bio-slurry, can be easily
collected and used as a potent organic fertiliser to enhance agricultural
productivity.8 A number of organizations are promoting biogas projects in Africa.910
2.2.
Solar energy technologies
Solar energy can be used for generating electricity, drying, heating and cooling
(through evaporation). Solar energy is most useful in areas of high and consistent
sunshine. Assessing the technical viability of solar energy technologies is relatively
simple because the sun is a reliable source
2.2.1. Solar photovoltaic (PV)
Solar PV panels convert sunlight directly into electricity. Solar PV is most
appropriate for low power requirements (a few watts up to a few kW), such as
lighting (with energy efficient light bulbs), radio, television, charging mobile phones,
refrigerators, small appliances and electric water pumps. A battery is usually
required to store the energy for usage during the evening. The panels can last
more than 20 years and provide a reliable supply of power with low maintenance
requirements. Solar PV has a high capital cost and the batteries (if included)
require maintenance and replacement during the life of the solar panel.
The energy available from a solar panel is dependent on the amount of solar
radiation that is incident on the panel (the amount the panel ‘sees’). Given the
power output of the solar panel (in Watts Peak) and the level of solar radiation for
the area (the kWh/day), the average available daily energy can be estimated. The
level of solar radiation at a site is dependent on the latitude and local climatic
conditions. It is a predictable variable; it has been mapped for all parts of the world
and data is available online.11 For applications such as vaccine refrigerators or
Renewable Energy to Reduce Poverty in Africa
13