BIOGAS USE IN
Biogas is a mixture of approximately 60% methane and 40% carbon dioxide, produced by the
breakdown of organic materials such as human excrement, dung or vegetable matter by bacteria.
The process of anaerobic digestion takes place in a sealed tank known as a digester, occurring at
slightly elevated temperatures; the most effective ranges are between 30 - 40°C for mesophilic
bacteria and 50 - 60°C for thermophilic bacteria (US Dept. of Energy, 2011), whilst it is far less
effective outside of these. Biogas is a clean, high grade fuel used for cooking, lighting and
generating electricity. It can be produced on a scale varying from a small household system to a
large commercial plant of several thousand cubic metres.
The bio-digestion of animal and human waste yields several benefits:
The production of methane for use as a fuel, which reduces the amount of woodfuel
required and thus reduces desertification.
The waste is reduced to slurry that has a high nutrient content, making an ideal fertiliser
which can be utilised as a commercial product or to improve the fertility of local arable
During the digestion process, dangerous bacteria in the dung and other organic matter are
killed, which reduces the pathogens dangerous to human health.
Biogas is a well-established fuel for cooking and lighting in a number of countries. China has over
7.5 million household biogas digesters, 750 large- and medium-scale industrial biogas plants,
and a network of rural 'biogas service centres' to provide the infrastructure necessary to support
dissemination, financing and maintenance. India has also had a large programme, with about
three million household-scale systems installed (Martinot, 2003). Other countries with active
programmes include Nepal, Sri Lanka, Kenya, and several in Latin America. As carbon emission
levels are becoming of greater concern and as people realise the benefits of developing
sustainable, low carbon energy supplies, then biogas becomes an increasingly attractive option.
Relation to People-Centred Reconstruction
The production and use of biogas by various methods has three general benefits (as described
above); the production of biogas can either compliment or replace traditional woodfuel or
biomass, helping to reduce local environmental damage, with increased energy security. People
producing their own energy supplies can reduce dependency on external sources, making them
less vulnerable to outside risks and shocks. Additionally, the production of fertiliser can improve
the condition of agricultural land, leading to increased food production and the possibility of
As well as helping people to become more independent and productive, the replacement of
smoke-producing woodfuels and the safe containment of harmful bacteria can have a significant
positive effect on wellbeing. All of these potential benefits are directly related to key aspects of
PCR. This technical brief provides an overview of various technologies to produce and use biogas.
It will discuss the practical applications of biogas technology and details some examples of where
it has benefitted a reconstruction scenario. The relevance and applicability of the technologies to
the three stages of reconstruction are discussed.
For the original document see Practical Action’s technical brief Biogas.
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