|Design, construction and maintenance of a Design, construction and maintenance of a biogas generator|
Biogas generators can be used at household or community level to produce usable fuel and fertilisers from human and animal waste. This document covers many of the technical aspects of designing, constructing and maintaining a biogas generator however does not explore the cultural, social and education facets of the project. These should be researched separately with reference made to the case studies within this document.
Biogas generators extract by-products from organic waste (including human and animal excreta, food stuffs, etc) which can be used to replace traditional fuels and fertilisers. Biogas generators produce 2 useful
1. Biogas – biogas is a natural gas which can be used directly as a fuel for cooking and heating or used to run a converted generator for electricity production.
2. Fertiliser – digested sludge from the bottom of the biogas generator and over-flow effluent water can be used as a fertiliser for crops The benefits of biogas generators are explicitly listed below and should be made clear when suggesting the construction of the biogas generator to users in order to improve speed and likelihood of acceptance:
1. Biogas generators provide a safe and cleaner way of storing excreta and subsequently bring about related advantages linked to safe sanitation
2. Biogas generators provide free fuel for cooking, heating and lighting
3. Biogas generators provide fertiliser for crops
4. Biogas requires far less time and effort to collect than other fuels (e.g. wood)
5. Biogas reduces the need for wood and therefore reduces deforestation and the burden on women of collecting wood
6. Biogas creates no smoke and therefore reduces health problems caused by burning other fuels indoors
7. Biogas is environmentally friendly and does not release as many greenhouse gases when burned compared to other fuels
8. Dangerous bacteria in faeces are killed during digestion in the biogas generator
Literature states that the biogas production rate of human excreta is 0.02-0.07m3/kg/day however the data varies greatly and is dependent on many variables (diet, food intake, water intake, climate, etc). Similar variance is apparent in human waste production data. Literature suggests that an average adult can be expected to produce 1-1.3kg of urine and 0.2-0.4kg of faeces per day  (if local figures are available then use these instead). GTZ suggest the following production rates of biogas from wastes of different animals per day in warm climates (in addition to human excreta other organic waste such as cattle dung can be added to the generator to increase biogas production)
|Design, construction and maintenance of a biogas generator|
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