The only gas lines here form at the family outhouse.

Peasants who farm this verdant patch of southwest China once were so hard up for household fuel that they spent half the day collecting straw to heat their dinners.

With typical Chinese resourcefulness, however, they solved their energy crisis through a novel kind of self-reliance: biogas.

Biogas is the popular term in China for methane produced from human and animal wastes. In Double Flow and other rural outposts of Sichuan province, it is the primary source of energy for cooking, lighting, drying crops, running farm equipment, heating chicken coops and generating electricity.

All a peasant needs to build his own power plant is shovel, pig and latrine. He digs a shallow hole and lines it with cement. Then, he connects "supply pipes" to adjacent privy and hog pen, seals the pit and waits 10 days for fermentation.

Clear, odorless gas eventually rises through rubber tubing from the Rube Goldberg contraption to lanterns or oven ranges. Simply turn a switch, strike a match and you have flame to light the house or cook your dinner.

For more sophisticated uses, such as fuel for farm vehicles, biogas can be compressed in tanks. Small power stations heat their boilers with biogas, turning electric generators for water pumps. In greenhouses, biogas burners provide the right temperature to cultivate rice seedlings.

"There is only so much oil and coal in the world, but biogas is unlimited as long as there is man," observed technician Ji Fangxing.

In the land of 1 billion lives, his comment was more than philosophical. China plans to double its energy output by the year 2000. But new coal and oil production is certain to go to factories and trains, not to the poor countryside.

Planners hope to compensate with alternative energy sources, chiefly biogas. By 1990, this poor-man's petroleum is expected to provide most energy needs for 100 million peasants, an eighth of the current rural population.

Sichuan has been the pacesetter for night soil power ever since biogas first was harnessed in the 1930s. Known for its pragmatism, the province already boasts enough biogas to serve 12 million people.

In rustic villages, biogas is the most advanced technology since the discovery of coal. Besides adding hours to leisure by eliminating the need to hunt for fuel, the pits save the cost of coal and kerosene--all for a onetime investment of $60.

For Double Flow's denizens, who never have heard of oil sheiks, energy now flows as naturally as it does in Kuwait. Every mud hut has its own biogas pit hooked to a maze of hoses and a pressure meter.

At nightfall, peasants light gas lamps that burn with 60-watt intensity.

Housewife Xu Guifang used to rise before dawn every day, strap a huge basket on her back and hunt for stalks and leaves to fire her oven. When she cooked, the plants caused such billows of smoke that her kitchen ceiling turned black.

"Now all I have to do is turn on the knob," she said, pointing to the gas range at the base of a crude oven carved out of rock.

Officials say peasants bucked the idea at first because they needed night soil for its traditional use as fertilizer. Then they discovered that biogas residue shoveled out of the pit makes for even richer compost.

"It looks a little thinner than the old stuff, but it does the job better," Zhang Yixiang of North River County commented.

In North River, peasants have tripled their biogas output by improving technology. Instead of covering their pits with cement, they build dark, plastic bubbles to trap the sun's heat that is needed in the fermentation process. They also have assembled storage tanks to hold the biogas for longer periods.

The careful handling of human waste has nearly wiped out North River's endemic intestinal worms and snail fever, diseases transmitted by untreated sewage tossed on open fields.

"We are self-sufficient in energy and wormless thanks to biogas," explained village leader Huang Qigao.

China is so high on biogas that it hopes to export the concept. For a small initial investment, you never have to worry about utility bills, blackouts or OPEC price hikes.

Of course, the idea is unfeasible in societies like the United States, where million-dollar plants are built to get rid of the stuff that turns on the lights here.

Rest easy, Pepco.