Greenspiration! Articles
A NEW AGE FOR SEWAGE:
China Lights The Way
by Tooker Gomberg and Angela Bischoff
Yes, China has enormous environmental problems. Over 2/3 of industrial wastewater is completely untreated. Urban air is often so polluted that it reaches levels several times the national standards.
But China is also the land of ecological transportation: 50-90% of all urban trips are still made by bicycle. Recycling is widespread; paper and many other materials are rarely discarded.
But there is one arena, largely unknown in the west, where China especially excels. Dare we say it? China has got its shit together.
Legendary alchemists strove to turn lead into gold. These days in villages and farms across China, the peasants are doing even better, turning feces into fuel and fertilizer. The production of biogas is widespread throughout rural communities in China, where 70 percent of China's 1.2 billion people live.
We first caught a whiff of China's biogas revolution while surfing the Internet. Then, while cycling through the southern Chinese city of Yulin, serendipity introduced us to an English teacher who helped us track down a government official who filled us in.
We were sipping tea with Zhuo Youxing, President of Energy Work with the Office for the Countryside, explaining to him our Greenspiration Odyssey of travelling the world with our bikes, looking for inspiring ecological stories, and writing about them. He listened politely, and then told us a bit about China's biogas program. What we really wanted to do was to go see some biogas units in actual use. He wasn't too helpful.
As a last resort we pulled out a letter of introduction a friend had written, in Chinese on Friends of the Earth, Hong Kong letterhead. That was the magical ticket we needed. Within minutes we found ourselves in a chauffeured government car speeding off to visit village biogas digesters. Throughout the hour-long expedition the driver incessantly honked the horn, sending pedestrians and cyclists scurrying for cover, in a scene reminescent of a Keystone Cops movie.
Carsick and on edge, we arrived in Beilu County's Zhonghe village, a prosperous community thriving from the sale of lichee fruit. Here, biogas is in widespread use, transforming human and pig waste into gas for cooking, lighting, and heating water. Already 400,000 people in Guangxi province alone are using biogas, and in China five million households rely on biogas digesters.
The system we saw was simple. Each family houses the pigs and the outhouse in a concrete and brick building near their home. All the waste, including anything biodegradable, goes directly into the biodigester, an underground tank below the outhouse, where the materials break down without oxygen. The by-product of the process is an odourless and colourless mixture of gases, mostly methane, and a nutrient-rich slurry often used for fertilizing crops.
The gas rises in the tank and is funnelled into a plastic tube. The tube snakes out of the building, through the tree branches into the kitchen. In the kitchen the gas is used for cooking and lighting, and for hot water for bathing. Energy efficient cooking utensils, like a wok and pressure cooker, ensure that the methane gas isn't wasted.
A family of three or four, with four pigs, can produce enough gas for all their cooking, lighting and water heating.
There are substantial benefits from using biogas. If feces are not properly treated or composted they can become a breeding ground for disease-causing organisms, and also can pollute waterways. The biogas digestion process kills pathogens.
"In the past, especially in the countryside, farmers went up to the hills and cut the trees for fuel to cook. And now, after we installed biogas pools, they don't need to go up to the hills and cut trees. In this way we can protect the forest. Each family can save 12 kg of wood. By the end of the year they can save 4000 kg" Mr. Zhou told us.
And burning wood or straw causes smoke, a hazardous source of indoor air pollution. Not a problem when biogas is used.
China's biogas program began in 1958, but really gained momentum in the 1970's. Officials are aiming that by the year 2002 there will be 100,000 pools in Beilu County, more than half the households. The longer term goal is to have every household equipped with a unit.
The unit, technically called a fixed dome Chinese model biogas plant, or drumless digester, is odourless and fly-less. This design was first built in China in 1936. The air/water-tight underground tank is made of easily available and inexpensive materials, mainly concrete and brick. It is 1.7 metres deep, 2.2 metres diameter, and is expected to be maintenence-free for 30-40 years. The cost to the farmer is an affordable 1,600 yuan (about C$300). Today anyone who wants one just needs to call the special office, and a technician will be on the way; the farmer purchases the materials and hires the labour him/herself.
"We are building the biogas units to develop ecological farming," Mr. Zhou said. Also, farmers that can cleanly handle their pig effluent can then acquire more pigs. And since electricity is expensive, costing approximately C$0.16 per kilowatt hour, a biogas unit can save money. The farmer can then plant more lichee fruit trees.
Mr. Zhou proudly exclaimed, "First, we can solve the energy problem, and second we can reduce the damage to the forest. And then we will have good, ecological recycling ... Of course I am happy with the success of the project. I am serving the people."
Imagine the day when visitors to your home contribute fuel for cooking and lighting, just by using your loo. Imagine turning sewage waste into resource in our western cities and towns. Shit - even the alchemists would be impressed.
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