Making low-tech inventions available to farmers in developing countries

Low Cost Ecological Energy Sources from Bio-Digesters Generating Methane Gas and Solar Generated Steam can both Generate Electricity

This is a discussion and collection of information focusing on low cost ways of generating energy with minimum pollution. In some cases the energy production can eliminate pollution from the air, ground and water. Initial topics focus on bio-digesters that generate methane and solar collectors that generate steam or at least hot water. Both steam and methane can be used for generating electricity.

Biodigester installation manual
Lylian Rodriguez and T R Preston
University of Tropical Agriculture Foundation
Finca Ecologica, University of Agriculture and Forestry,
Thu Duc, Ho Chi Minh City, Vietnam

Biodigesters can play a pivotal role in integrated farming systems by reducing health
risks, facilitating control of pollution and at the same time adding value to livestock
excreta through production of biogas and improved nutrient status of the effluent as
fertilizer for ponds and crop land. Energy is also a fundamental factor for economic
development” of biodigester systems.
“In many developing countries there is a serious shortage of fuel and the energy crisis is a
daily reality for most families. Cooking is one of the most energy-consuming activities,
yet is often inefficient. The open fire is still very common.

Biogas technology transfer in small scale farms in
Northern provinces of VietNam

Bui Van Chinh, Le Viet Ly, Nguyen Huu Tao
and Nguyen Giang Phuc
National Institute of Animal Husbandry, Ha Noi

During the last twelve years, animal production on small-scale farms in Northern Vietnam has developed rapidly. Biogas technology transfer has been an important element in these activities. Biodigesters made of polyethylene tube (cheap biodigester) and by brick - cement (solid dome) construction have been well accepted by small-holder farmers. The former are popular in upland areas; while the latter are favoured in the low-lying delta where farms are smaller and space is limited. The most effective way to set up introduce these biodigesters in Northern Vietnam has been through pilot demonstrations followed by training and extension.
Key words: Bjodigsters, small-scale farm, polyethylene tiube, solid-dome

The Introduction of Low-Cost Polyethylene Tube Biodigesters on Small-Scale Farms in Vietnam


In recent years, the conversion of biomass to methane for use as an energy source has excited interest throughout the world. Biogas digestion was introduced into developing countries as a low-cost alternative source of energy to partially alleviate the problem of acute energy shortage for households. However, few farmers used biogas in practice. The poor acceptability of the digesters is believed to be due mainly to the high cost of the digesters, difficulty in installing them and difficulty in getting spare parts. The biogas programs developed quickly in some developing countries only under substantial support from governments and aid agencies (Gunnerson,, 1986; Kristoferson and Bokalders, 1991; Marchaim,, 1992; Karki,, 1996). Besides, the replacement of worn-out parts posed another technical problem, in addition to the fact that such spare parts were not always locally available.
Many developing countries, such as Colombia, Ethiopia, Tanzania, Vietnam, Cambodia and Bangladesh promoted the low-cost biodigester technology aiming at reducing the production cost by using local materials and simplifying its installation and operation (Solarte, 1995; Chater, 1986; Hieu et al, 1994; Sarwatt, 1995; Soeurn, 1994; Khan, 1996). To this end it was decided to use a continuous-flow flexible tube biodigester based on the bag digester model as described by Pound et al (1981) and later simplified by Preston and co-workers first in Ethiopia (Preston, unpubl.), Colombia (Botero and Preston, 1987) and later in Vietnam (An et al, 1994). Within three years, more than 800 polyethylene digesters were installed in Vietnam, mainly paid for by farmers (An and Preston, 1995).
The objectives of this study were to assess the effects of low-cost biodigesters in small farms in Vietnam and to identify experiences, effects, constraints and problems associated with this technology.

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