Benefits of using biogas in households experience from a user in Uganda
Sendegeya , Al-Mas
Ssebuwufu , Pancras John
Da Silva, Izael Pereira
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This paper discusses the socio-economic benefits of using biogas based on the experience of a long term user as a typical example. A floating drum type of digester was installed with a capacity of 6.5 m3 in the year 2000 at a total cost of US$ 1,830. The gas generated is used exclusively for cooking. For the user, his typical kitchen day consists of three meals for a household of 8 people. Prior to the installation of the biogas plant, the user was using liquefied petroleum gas (LPG) supplied in 15 kg cylinders at an average cost of US$ 23 per cylinder and used to consume an average of 3 cylinders in 2 months bringing a monthly expenditure on the kitchen fuel of US$ 35 including transport costs for the cylinder. The user has now totally substituted LPG with biogas which translates into an annual average saving of US$ 420. At this rate of saving, the break-even point for the full recovery of the installation costs is about five years. Since installation the digester has not had any significant breakdown, so no major maintenance has been required. The water used for mixing the cow dung into slurry is harvested rainwater. Thus according to his experience it indicates that the use of biogas offers a substantial cost saving on domestic energy. In addition to the economic benefits, other benefits include increased organic agricultural production when the sludge is used as fertiliser. The use of the slurry as bio-fertiliser on his small vegetable farm (about 0.5 ha), has helped him to save money that would have been used to buy the imported artificial fertilisers. Fermenting the cow dung in a biogas digester instead of composting it in open air provides several other advantages, ranging from a foul odour-free environment to improvements in the general health conditions in the home. Thus, a reduction in the unhealthy smell from the compost dumps where the cow dung used to be deposited, as well as a reduction in free methane gas (one of the green house gases, GHG) which used to be emitted direct into the atmosphere by the decomposing dung.