SICHUAN'S HOME-SCALE BIOGAS DIGESTERS

Image Gallery A group of commune members excavate a biogas pit .... A typical Sichuan family digester is compact and allows for periodic cleanouts . . . . Larger methane ""plants""arc sometimes covered with ponds, which are used to culture aquatic vegetation

MOTHER's recent tour to China brings us this report on one of that nation's solutions to some of its health, food, and energy problems.

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 dis covered, you see, that biogas (the volatile fuel that results from the controlled fer mentation 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 waste disposal, health, fertilizer supply, and other problems that are not directly energy-related have also been alleviated by the implementation of local methane production programs!

THREE WITH ONE BLOW

The Chinese have been experimenting with biogas made from farm and house hold 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 ... and there are now about seven million small-scale fuelproducing 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 shortterm 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 Sichuanbased 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 ... as opposed to outright losses of 82%—by way of evaporation—of the same kind of raw material's potential ammonia when it's left in compost piles. The usable phosphate content of the "biogassed" waste also showed an improvement: 31% over that of conventionally composted mixtures.