Firewood, agricultural wastes and animal wastes are the materials needed – which are readily available – for producing biogas in an anaerobic digester. Many countries have large cattle and buffalo herds producing tons and tons of manure. As biogas plants yield good quality sludge fertilizer, the biogas fuel and/or electricity generated is an additional bonus. And this has motivated the large biogas programs in a number of developing countries starting with China.
China began mass adoption of biogas in 1975 under the slogan "biogas for every household" Within the first few years 1.6 million digesters were constructed annually. By 1992, five million family-sized plants were operating. In a report titled "Biogas in India: A Sustainable Energy Success Story," the authors identified women and children as the major beneficiaries of biogas in India, where every year – 200,000 families – turn away from traditional fireplace and have biogas plants installed to provide energy for cooking and lighting. By 2000, more than two million biogas plants had been built in India and almost 200,000 permanent jobs created.
In Vietnam as in other developing countries – Bangladesh, Colombia, Ethiopia, Sri Lanka, Tanzania, Cambodia and Bangladesh – the polyethylene tubular digester was promoted to reduce production cost by using local materials and simplifying installation and operation. The resulting low-cost digesters were installed and mainly paid for by the farmers, especially when farmers participate fully in the necessary maintenance and repair work. Within 10 years, more than 20,000 polyethylene digesters are fully integrated into the farming system.
That biogas brings numerous ‘benefits are now generally recognized. It has resulted in a smoke-free and ash-free kitchens so women and children are no longer prone to respiratory infections, and can look forward to longer and healthier lives Women in rural communities are spared the burden of gathering firewood (a load 60-80 lbs. A week). That, and the practice of containing livestock for manure collections, – which might, otherwise, graze in the forest – allowing the forest to maintain and regenerate its plants.
In rural areas where there is, otherwise, no electricity supply biogas provides lighting in evening study, literacy classes and other home and community activities. As a result, cattle dung is no longer stored in the home but is fed directly to biogas digester along with toilet wastes. The anaerobic process also destroys pathogens greatly improving sanitation.