Biogas, a by-product of farmyard waste-treatment, has emerged as a major boon for Third World countries, bringing health, social, environmental, and financial benefits Dr. Mae-Wan Ho
The United Nations Development Programme (UNDP) 1997 Report, Energy After Rio: Prospects and Challenges [1] identified community biogas plants as one of the most useful decentralized sources of energy supply. Unlike the centralized energy supply technologies, such as power plants based on hydroelectricity, coal, oil or natural gas, that have hitherto been the only choices open to rural communities, biogas plants do not require big capital to set up, and do not pose environmental problems that excite public opposition. Instead, in most cases, they offer solutions to existing environmental problems, and many unexpected benefits besides.
The organic materials needed for producing biogas in an anaerobic digester are readily available in developing countries. These include firewood, agricultural wastes and animal wastes. Many countries have large cattle and buffalo herds producing tonnes of manure. Traditionally, these wastes are carefully collected in India and used as fertilizer, but the increasing scarcity of firewood has forced many villagers to burn dung-cakes in cooking their food.
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 programmes 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, but these were of low quality; and by 1980, half of all digesters were not in use and the rate of adoption had slowed. By 1992, only 5 million family sized plants were still operating, many of them redesigned to avoid leakage [2].
In India, as in China, a too-rapid implementation policy in the early 1990s exceeded the capacity of India's research and development organizations to produce reliable designs and to optimise digester efficiency. The situation has improved since, especially with the introduction of a low-cost polyethylene tubular digester. Now, everyone in India installing a biogas plant has the right to an allowance paid by the central government [3].
In a report, Biogas in India: A Sustainable Energy Success Story [4], the authors identified women and children as the major beneficiaries of biogas in India, where every year, 200 000 families turn away from the traditional fireplace and have a biogas plant installed to provide energy for cooking and lighting. By 2000, more than 2 million biogas plants have been built in India and almost 200 000 permanent jobs created.
India's early difficulties and recent success is being replicated in countries such as Nepal [5], Sri Lanka [6] and Vietnam [2].
In Vietnam, as in other developing countries - Colombia, Ethiopia, 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 digester has been well received by poor farmers, especially when farmers participate fully in the necessary maintenance and repair work. Within ten years, more than 20 000 polyethylene digesters were installed and mainly paid by the farmers themselves. However, the digesters are still not fully integrated into the farming system, as there is only limited use of the effluent as fertilizer for fish and crops (“Dream farms”, this series). There are also potentials for improving the digester for greater efficiency, ease of maintenance and durability. More cooperation between scientists and farmers and credit systems for poor farmers to install digesters will also help to increase the adoption rate.
In Sri Lanka, biomass accounts for 45% of the country's energy needs, with petroleum and hydroelectricity supplying 41% and 14% respectively [7]. Sri Lanka's economy is still largely based on agriculture. A major constraint to production is the increasing cost of fertilizer, while solid waste, mainly organic, is collected and disposed at a large number of unprotected sites, affecting the health of the poorest.
Although biogas digesters have been introduced in Sri Lanka since the 1970s, poor design, lack of maintenance skills and insufficient capacity to deal with the problems meant that only a third of the 5 000 units installed functioned properly [6]. The Intermediate Technology Development Group (ITDG) started a project in 1996 to improve the success rate of the units on a national level by setting up demonstration units to help spread information, restoring abandoned units and training users to operate and maintain them. In addition, individual farmers get help to install biogas units on their farms to make use of the manure from their cows.
Mr. Ratnayake is one of the lucky farmers. With nothing more than cow dung, he now has enough power to cook with, iron the laundry and provide heat and light for his home without using a single piece of wood. All he has to do is to collect the manure from his cows in a specially adapted cattle shed where they feed, mix it with water and leaves it to ferment in a large concrete tank or pit. The gas produced is collected in a simple storage tank, from where it is piped into his house to use.
The women and children, freed from firewood collection and from cleaning smoke-blackened utensils and the disposal of animal waste, gain some two hours a day for other activities. About 80% now use this time to earn extra income that currently accounts for approximately 24% of the family's monthly income. Another advantage of using biogas is that there is very little waste from the process and it is environmentally friendly.
The dried manure left after biogas is generated is richer than ordinary manure and makes a fantastic organic fertilizer for Mr. Ratnayake's crops, which he can sell at a higher price as organic produce.
The many benefits of biogas are now generally recognized. It has resulted in a smoke-free and ash-free kitchen, so women and their children are no longer prone to respiratory infections, and can look forward to longer, healthier lives. Women are spared the burden of gathering firewood, a load of 60-80lb per week, which can take up to one day a week. That, and the practice of containing livestock for manure collection, which might otherwise graze in the forest, both contribute to protecting the remaining forests and allowing the forests to regenerate.
The sludge remaining after digestion is richer in valuable nutrients than the animal manure, providing vegetables, fruits and cereals with a top quality fertilizer that guarantees better crops.
In rural areas where there is otherwise no electricity supply, biogas has enabled women to engage in evening study, literacy classes and other home and community activities.
Cattle dung is no longer stored in the home, but is fed directly to the biogas digester along with toilet waste. The anaerobic digestion process also destroys pathogens. As a result, sanitation has greatly improved.
There are other benefits for countries that decide to adopt biogas. The United Nations Framework Convention on Climate Change has set up a Clean Development Fund, and the World Bank has put together a Carbon Finance Unit to allow rich countries, which are pumping more carbon into the atmosphere than is allowed under the Kyoto Protocol, to buy emissions that poor countries prevent through conserving forests or promoting renewable energy. An article in the Nepali Times [8] pointed out that Nepal's successful biogas programme not only brought farmers a non-polluting fuel, conserved forests and provided high quality fertilizer for crops; it can make the rest of the world pay hard cash for not burning firewood to release carbon dioxide into the atmosphere.
About 85% of the fuel used in Nepal comes from biomass sources like firewood, animal manure and agricultural residue. The remainder, kerosene, diesel or liquefied petroleum gases. Its biogas programme would not have been possible if the users had not received subsidies. Each biogas unit costs $300 to set up, but the government pays one-third of the amount.
Nepal's biogas programme is internationally regarded as a model for successful use of alternative energy for the rural Third World. Nepal has now overtaken China and India in the number of biogas plants per capita. Each of its 125 000 functioning digesters prevents five tonnes of carbon dioxide equivalents from being pumped into the atmosphere every year. This ‘saved' greenhouse gas is what rich countries are buying to offset their own emissions, and is worth US$5 million. This money can be invested back into clean energy that would make Nepal eligible to trade even more carbon offset to rich polluters.
“We have an initial agreement with the World Bank,” said Sundar Bajgain, executive director of the Biogas Support Project, which has played a leading role in installing biogas plants in private houses in 66 districts across the country. The biogas model can be applied to other renewable energy sources such as hydropower (under 15MW, as recommended by the International Panel on Climate Change) and solar power to reap rewards from carbon trading.
Admittedly, paying cash to poor countries not to burn firewood is a measure of desperation for rich countries like the United States, which, at 4.6 percent of the world's population and growing, is responsible for 25 percent of global greenhouse gas emissions due to human activities [9]. It would make much better sense for developed countries to cash in on the benefits of biogas themselves (“Bug power”, this series), as they also have greater capacity for research and development to optimise the production and use of biogas.
Article first published 20/06/05
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