Biogas: China’s Solution for Energy, Health and Environment

Gongcheng, China – Farmer Ou Yuqun, 57, is a member of the Yao ethnic group in Gongcheng, located in the Guangxi Autonomous Region in southwest China. All her three children are grown up. Last year she moved to a new house where she feels relaxed and happy. 

There is something else that makes her even happier–the new biogas system installed in her house. 

She cooks with biogas; some of the lights in her house are powered by biogas; the house’s toilet waste goes to a digester; and the slurry from the digester fertilizes the vegetables she plants in the backyard. 

“This biogas system is great!” she says. 

Bringing Sufficient Energy and Better Health 

The “great” system Ou talks about is part of the World Bank-supported Eco-farming Project. Since 2008, the project has benefited around 500,000 rural households in 64 counties in five provinces–Anhui, Chongqing, Guangxi, Hubei, and Hunan. Through the project, biogas digesters and stoves were installed in homes, animal sheds, toilets and kitchens built or rehabilitated to accommodate the system. 

Tang Fuluan, director of Gongcheng’s Bureau of Agriculture, said the biogas project is very much suited to local conditions. Ou’s and neighboring villages plant persimmon trees which produce high-value specialty fruit. Households also raise poultry and pigs and the year-round warm and humid weather is conducive for growing many plants. 

Residue from processing persimmons, weeds pulled from the groves, animal manure, and human waste are all thrown into biogas digesters, delivering vital energy to rural communities, said Tang. 

“I use biogas to cook all the three meals of the day,” Ou said. 

Jiang Liangde, also a villager of Gongcheng, shares the sentiment. 

Jiang, 60, lives by himself. His three sons have all moved to cities and his wife recently went to stay with one of them to help take care of a newborn grandchild. 

He grows rice, tangerines, peanuts, and watermelon and uses slurry from the biogas system as fertilizer. 

After work, he makes “oil tea” (a local drink similar to broth) for himself using biogas.  

“It is very efficient,” he said. “In just a few minutes, I can enjoy the tea. And what I get every day is more than I can use.” 

Thanks to the project, Jiang also got a new toilet. “The toilet used to be a small shed. Lots of flies flew around. Now it is modern and clean. The flies are gone,” he said. 

Before switching to biogas, local farmers used firewood they collected from the persimmon groves as fuel for cooking. 

“I still remember the days when I picked up firewood while my bulls grazed. Very tough work! It took me 2-3 hours a day,” Ou said. “There was lot of smoke when we burned firewood. The smoke made my grandchildren cry. Now my kitchen is clean and smoke-free, which is also good for our health.” 

Environmental benefits

For Ou and her fellow villagers, biogas means convenience, less work and less smoke. But the project has even more benefits. 

“In the bigger picture, it means using less fossil fuel and reducing the emission of greenhouse gases,” said Cao Wendao, a senior agricultural specialist with the World Bank. 

On average, a biogas digester would annually reduce 2.83 tons of CO2 emission. Assuming that in carbon trade, per ton of CO2 emission is priced at RMB79 ($12), biogas unites at the mature stage of the project would displace about 1.55 million tons of greenhouse gases, generating a value of RMB 122.7 million (US$ 20 million) per year, Cao said. 

Biogas replacing firewood also helps prevent deforestation. And using slurry from the digesters as fertilizer reduces farmers’ use of chemical fertilizers and helps maintain soil quality, according to Tang, the Gongcheng agricultural official. 

The environmental benefits do not stop there. 

In Gongcheng, like many rural areas in China, animal farms are a growing industry. But the improper disposal of animal waste poses a big problem: it pollutes waterways and the waste naturally emits methane, a greenhouse gas 23 times more potent than carbon dioxide. 

So “biogas management companies” were established to solve this problem.  

“For example, just in our township alone, there are about 50 pig farms. Without treatment, pig waste causes pollution,” said Fan Jiaqiang, who works with a biogas management company. 

“Our company signed an agreement with pig farms to help dispose the waste which we bring to farmers to feed their biogas digesters. This way, we ensure adequate supply of waste for biogas and also reduce pollution caused by large pig farms,” he said.