Where wood and other fuels are in short supply, people often dry and burn animal manure. This may seem like a logical use of waste biomass, but it can intensify food shortages in poorer countries. Not putting this manure back on the land as fertilizer reduces crop production and food supplies. In India, for example, where fuel wood supplies have been chronically short for many years, a limited manure supply must fertilize crops and provide households fuel. Cows in India produce more than 800 million tons of dung per year, more than half of which is dried and burned in cooking fires. If that dung were applied to fields as fertilizer, it could boost crop production of edible grains by 20 million tons per year, enough to feed about 40 million people.
When cow dung is burned in open fires, more than 90 percent of the potential heat and most of the nutrients are lost. Compare that to the efficiency of using dung to product methane gas, and excellent fuel. In the 1950's, simple, but they were not widely used. In China, 6 million households use biogas for cooking and lighting. Two large municipal facilities in Nanyang will soon provide fuel for more than 20,000 families. Perhaps other countries will follow China's lead.
Methane gas is the main component of natural gas. It is produced by anaerobic decomposition of any moist organic material. Many people are familiar with the fact that swamp gas is explosive. Swamps are simply large methane digesters, basins of wet plant and animal wastes sealed from the air by a layer of water. Under these conditions, organic materials are decomposed by anaerobic (oxygen-free) rather than aerobic (oxygen-using) bacteria, producing flammable gases instead of carbon dioxide. This same process may be reproduced artificially by placing organic wastes in a container and providing warmth and water. Bacteria are ubiquitous enough to start the culture spontaneously.
Burning methane produced from manure provides more heat than burning the dung itself, and the sludge left over from bacterial digestion is a rich fertilizer, containing healthy bacteria as well as mos t of the nutrients originally in the dung. Whether the manure is of livestock or human origin, airtight digestion also eliminates some health hazards associated with direct use of dung, such as exposure to fecal pathogens and parasites.
All sizes and forms of containment have been used for methane production, from coffee cans to oil drums to specially designed tanks. Like other bacteria and yeast cultures, such as those used for bread, yogurt, and beer, methane-producing cultures need heat to thrive. The highest gas production is generally at 35 degrees Celsius, but once a culture is established, it produces enough of its own heat to continue. This warmth can be felt in all backyard compost heaps.
Methane is a clean fuel that burns efficiently. It is produced in a low -technology, low-capital process from any kind of organic waste material: livestock manure, kitchen and garden scraps, and even municipal garbage and sewage. In fact, municipal landfills are active sites of methane production, contributing as much as 20 percent of the annual output of methane to the atmosphere. This is a waste of valuable resource and a threat to the environment because methane absorbs infrared radiation and contributes to the greenhouse effect. Some municipalities are drilling gas wells into landfills and garbage dump. Cattle feedlots and chicken farms in the United States are a tremendous potential fuel source.
Collectible crop residues and feedlot wastes each year contain 4.8 billion gigajoules of energy, more than all the nations farmers use. Municipal sewage treatment plants routinely use anaerobic digestion as a part of their treatment process, and many facilities collect the methane they produce and use it to generate heat or electricity for their operations. Although this technology is well-developed, its utilization could be much more widespread.
By Bernard Fenley
When cow dung is burned in open fires, more than 90 percent of the potential heat and most of the nutrients are lost. Compare that to the efficiency of using dung to product methane gas, and excellent fuel. In the 1950's, simple, but they were not widely used. In China, 6 million households use biogas for cooking and lighting. Two large municipal facilities in Nanyang will soon provide fuel for more than 20,000 families. Perhaps other countries will follow China's lead.
Methane gas is the main component of natural gas. It is produced by anaerobic decomposition of any moist organic material. Many people are familiar with the fact that swamp gas is explosive. Swamps are simply large methane digesters, basins of wet plant and animal wastes sealed from the air by a layer of water. Under these conditions, organic materials are decomposed by anaerobic (oxygen-free) rather than aerobic (oxygen-using) bacteria, producing flammable gases instead of carbon dioxide. This same process may be reproduced artificially by placing organic wastes in a container and providing warmth and water. Bacteria are ubiquitous enough to start the culture spontaneously.
Burning methane produced from manure provides more heat than burning the dung itself, and the sludge left over from bacterial digestion is a rich fertilizer, containing healthy bacteria as well as mos t of the nutrients originally in the dung. Whether the manure is of livestock or human origin, airtight digestion also eliminates some health hazards associated with direct use of dung, such as exposure to fecal pathogens and parasites.
All sizes and forms of containment have been used for methane production, from coffee cans to oil drums to specially designed tanks. Like other bacteria and yeast cultures, such as those used for bread, yogurt, and beer, methane-producing cultures need heat to thrive. The highest gas production is generally at 35 degrees Celsius, but once a culture is established, it produces enough of its own heat to continue. This warmth can be felt in all backyard compost heaps.
Methane is a clean fuel that burns efficiently. It is produced in a low -technology, low-capital process from any kind of organic waste material: livestock manure, kitchen and garden scraps, and even municipal garbage and sewage. In fact, municipal landfills are active sites of methane production, contributing as much as 20 percent of the annual output of methane to the atmosphere. This is a waste of valuable resource and a threat to the environment because methane absorbs infrared radiation and contributes to the greenhouse effect. Some municipalities are drilling gas wells into landfills and garbage dump. Cattle feedlots and chicken farms in the United States are a tremendous potential fuel source.
Collectible crop residues and feedlot wastes each year contain 4.8 billion gigajoules of energy, more than all the nations farmers use. Municipal sewage treatment plants routinely use anaerobic digestion as a part of their treatment process, and many facilities collect the methane they produce and use it to generate heat or electricity for their operations. Although this technology is well-developed, its utilization could be much more widespread.
By Bernard Fenley
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