The couple belongs to the Tujia ethnic group and has five adult children: four daughters and a son. All the children are married and working in big cities, so the couple unfortunately does not have any help on the farm. For this reason, they are very happy that they no longer need to collect wood in the forest. "It was a pain and took a lot of time," says Zhang MingGan, smiling. Now the kitchen is clean and cooking is quicker and easier Zhang says. "Now food can be made in 20 minutes! Before, the cooking often took half the day”. Now they enjoy improved hygiene and a better life, but Zhang is probably most enthusiastic about the increased yields in the years to come as a result of the organic fertilizer that comes out as a "bonus product" from the biogas tank after the methane gas has disappeared. He has noticed that the crops already are better than before. Mr Zhang is thankful that he can use the organic fertilizer from the biogas tank on his garlic, onions, cabbages, carrots and oranges.
How does the biogas tank work? Biogas is formed when animal (or human) dung and other compost are inserted into the digester and become methane gas in the tank under the ground. This gas has no smell or smoke and can be used for cooking and lighting fires. When the mixture has released the gas, it comes out as organic fertilizer of high quality. That means Qingxiu Zhang and Gu Zhengyi not only get gas for cooking and light, but they also receive high quality organic fertilizer that increases their crop yields.