Sichuan's Home Methane Digesters

A recent MOTHER EARTH NEWS tour to China revealed the nation was using home methane digesters to solve some of its health, food, and energy problems.

  • 069 sichuan home methane digester - typical family digester
    A typical Sichuan family's home methane digester is compact and allows for periodic cleaning.
  • 069 sichuan home methane digester2 - excavating a pit
    A group of commune members excavate a pit for a home methane digester.
  • 069 sichuan home methane digester - pond
    Larger methane "plants"are sometimes covered with ponds, which are used to culture aquatic vegetation.
  • 069 sichuan home methane digester - diagram
    Diagram shows the components and construction of a typical household methane digester.

  • 069 sichuan home methane digester - typical family digester
  • 069 sichuan home methane digester2 - excavating a pit
  • 069 sichuan home methane digester - pond
  • 069 sichuan home methane digester - diagram

The People's Republic of China, with its vast territory and sizable rural population, has long been plagued with a shortage of energy. And since the use of modern equipment has lately become more prevalent—because the Asian land has started to develop its decentralized, nonurban regions—this fuel deficit would certainly have worsened had it not been for some farsighted planning on the part of China's citizenry.

The Oriental experimenters have discovered, you see, that biogas (the volatile fuel that results from the controlled fermentation of organic waste material) can be a very practical substitute for the more conventional sources of energy, which people in many sections of rural China find difficult to obtain. Furthermore, a number of problems that are not directly energy-related—waste disposal, health, and fertilizer supply—have also been alleviated by the implementation of home methane digesters for local biogas production.

Three With One Blow

The Chinese have been experimenting with biogas made from farm and household waste for nearly 30 years, undergoing a self-education process based upon the country's long-standing tradition of composting all available human, animal, vegetable, and crop refuse to make organic fertilizer. Within the last decade, however, the results of that research have been put to good use. There are now about seven million small-scale fuel-producing methane plants in operation throughout China, many of them within the Sichuan Province, which is located in the nation's southeastern region.

Understandably enough, the switch to biogas energy has had an enormous impact on the economic growth of this rapidly "modernizing" country. In the past, rural inhabitants had to either forage for firewood or purchase coal or charcoal to satisfy their cooking needs. These practices not only stripped the countryside of forests (and the fields of organic residue), but also put a strain on mining and transportation facilities and were highly labor-intensive.

From an agricultural standpoint, the production of methane fuel also makes a lot of sense. Obviously, there's only a short term gain to be realized by burning crop residues for fuel, but the closed fermentation process typically used in biogas "pits" allows the full potential of cull and waste material to be seen.

The official figures for various Sichuan-based methane plants show that the ammonia content of an organic fertilizer mix which has been fermented for 30 days in an enclosed digester is increased by over 19%, while reports from other provinces indicate that gains of up to 160% are possible; when it's left in compost piles, the raw material loses 82% of its potential ammonia content by way of evaporation . The usable phosphate content of the "biogassed" waste also showed an improvement: 31% over that of conventionally composted mixtures.

10/27/2009 9:36:57 AM

Sent in by a reader: A Construction Manual for a 3-CUBIC METER BIOGAS PLANT

9/15/2009 2:45:36 PM

I am sorry, it is not.

9/15/2009 2:35:17 PM

Is the Chinese Biogas Manual still available?



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