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close this bookBioconversion of Organic Residues for Rural Communities (UNU, 1979)
close this folderBiogas generation: developments. Problems, and tasks - an overview
View the document(introduction...)
View the documentIntroduction
View the documentWhat is biogas?
View the documentMicrobiology of CH4, or bio-methanogenesis
View the documentThe biogas plant-some technical considerations
View the documentEnvironmental and operational considerations
View the documentDevelopments and processes for rural areas
View the documentCost-benefit analyses
View the documentHealth hazards
View the documentBottlenecks, considerations, and research and development
View the documentReferences
View the documentDiscussion summary

Developments and processes for rural areas

Two years ago, the Economic and Social Council of the United Nations adopted a survey, presented in 1978 to the Committee on Science and Technology for Development, listing the on-going research and development in unconventional sources of energy. From the point of view of the developing countries, it is heartening to note that the "use of farm wastes to produce methane" has also been identified in the United Nations World Plan of Action for the Application of Science and Technology to Development.

The Economic and Social Council for Asia and the Pacific, moreover, adopted the Colombo Declaration at its thirtieth session, which determined that the most urgent priorities for action are in the fields of food, energy, raw materials, and fertilizers, and that these priorities would be best met by the integrated biogas system (IBS).

An integrated system aims at the facile generation of fertilizer and acquisition of energy, production of protein via the growth of algae and fish in oxidation ponds, hygienic disposal of sewage and other refuse, and is a tangible effort to counteract environmental pollution. The heart of the system is the biogas process; it has the potential to "seed" self-reliance in relatively primitive economies (14, 22, 23). Allied benefits include the development of rural industry, the provision of local job opportunities, and the progressive eradication of hunger and poverty (Figures 4 - 7).

Figure. 4. Two Ways of Increasing Fertilizer Production Target: 230,000 tons of nitrogen fertilizer per year. (Adapted from A.K.N. Reddy, Uniterra, Vol. 1, 1976)

Figure. 5. Biogas Cycle in China (Source: FAO Soils Bulletin 40, Rome, 1977)

Figure. 6. Interactive Loop of Rural or Village Farming System Based on Biogas or Methane Economy

Figure. 7. A Proposed Integrated Nuclear Cooling and Organic Waste Disposal System (After W. Oswald, University of California)

The coupling of a photosynthetic step (24 - 26) with digestion provides for the transformation of the minerals left by digestion directly into algae that can then be used as fodder, as feed for fish, as fertilizer, or for increased energy production by returning them to the digester process (Figure 8).

Figure. 8. Simplified Scheme Indicating Various Combinations of Digestion and Photosynthesis for Fodder, Fertilizer, and Fuel Production (After J.W.M. LaRivière, J. Sci. Soc., Thailand, 1977)

The IBS aims at putting back into soil and water what has been taken from them, and increasing the amounts of nutrients by fixing CO2 and N2 from the atmosphere into the soil and water through photosynthesis by algae. Involving low cash investments on a decentralized basis, the implementation of IBS provides employment to the whole work force without disruption of the rural structure. Furthermore, it is an apt example of soft technology that does not pollute or destroy the physical environment. At the College of Agriculture of the University of the Philippines, preliminary work on a small scale has begun. In England, an Eco-house (Figure 9) has been built by Graham Caine on the Thames Polytechnical Playing Fields at Eltham, southeast of London. Results on the project, however, are not yet available.

Figure. 9. Graham Caine Eco-House (Reprinted with permission from Mother Earth News, No. 20 [March 1973], p. 62)