Wetenschap - 31 mei 2010

Bio-energy can replace petroleum in Kenya

Think about this: producing 1300 million cubic metres of methane annually from agriculture waste in Kenya. A third of such agriculture residue could be fermented directly. Kenya would have enough to replace the fossil fuels which it now imports.

This conclusion will be drawn by environmental technologist Henri Spanjers and Belgian and Kenyan researchers in the next edition of Renewable Energy. Spanjers is associated with the Lettinga Associates Foundation (LeAF), named after Emeritus Professor Gatze Lettinga, who developed the anaerobic (oxygen-free) environmental technology.
The researchers began by calculating the volume of waste products in the cultivation of maize, cotton and barley. The residue of these crops can be easily converted into methane during fermentation. Tests carried out in the environmental technology laboratory in Wageningen have shown that a ton of maize rubble can produce 363 cubic metres of methane, a ton of cotton rubble gives 365 cubic metres of methane, and from barley comes 271 cubic metres of methane.
Fermentation of all the waste products of these crops would churn out 1300 million cubic metres of methane. This could be converted into 3900 gigawatt hours of electricity, which form three quarters of the current energy production in Kenya. Currently, residue from the agriculture sector are usually ploughed back into the soil, processed into compost, or discarded at dumping grounds, says Spanjers. 'The last of that causes concern, because when waste ferments in the dumping grounds, it releases the greenhouse gas methane into the environment.'
Kenya is not doing much about methane production at present. To harness the potential of methane in green waste streams, Kenya needs to have organizational and political changes, says Spanjers. 'Farmers can't do much with the waste on their own. You would have to set up cooperatives, for example, to collect the waste and to process it.' His idea is to have relatively small bio-gas installations catering to local energy needs. 'The technology is not complicated; we know how to do it.'
The first author of the article is Charles Nzila, who receives financial support from LeAF and the Flemmish University Development Cooperation. In the next phase of his research, Nzila will do a life cycle analysis to determine the sustainability of this approach. He will also examine the costs of the bio-gas installations and look into what the Kenyans can do with the digestate, the waste product of fermentation. Spanjers will supervise the research work, together with Jo Dewulf of the Ghent University. He wants to help to set up a bio-gas research centre in Kenya where knowhow concerning methane production can be assembled.