This type of digester domes are built by excavating the soil and then made the building with bricks, sand, and cement-like cavity air tight and structured like a dome (half sphere ball). This type is developed in China so called dome type or types of China (see picture). In 1980 as many as seven million units this tool has been built in China and its use covers to move agricultural equipment and for electric power generators. There are two types of small size for households with a volume of 60-10 cubic meters and large type for groups of 60-180 cubic meters.
India and China are two countries which have no oil energy sources so that their long been very actively developing alternative energy sources, including biogas.
In the methane digester bacteria to process waste or biomass and bio-methane to produce biogas. With a pipeline that is designed in such a way, the gas can be flowed to the stove is located in the kitchen. These gases can be used for culinary purposes and others. Biogas is produced by mixing waste consisting largely of cattle dung with small pieces of plant debris, such as straw, etc., with plenty of water.
For the first time it would take approximately two weeks to a month before the beginning of the gas produced. The mixture was always added every day and occasionally stirred, while that have been processed out through the outlet. The rest of the waste that has been digested by bacteria or bacterial methane biogas, called a slurry or sludge, has the same nutrient content of organic fertilizers that have matured as well as the compost so that it can directly be used to fertilize crops, or if it will be stored or sold can be dried in the sun before it is inserted into in sacks.
For starters it is needed the cost to build the plant (digester) biogas is relatively large for the rural population. But once established, the tool can be used and produce biogas for years.For the size of 8 cubic meters dome type tool, suitable for farmers who have 3 or 8 cows or goats, 100 chickens on the side also has adequate water resources and waste biomass crops as a complement. Each unit is filled as much as 80 kilograms of cow dung mixed with 80 liters of water and pieces of other wastes to produce 1 cubic meter of biogas that can be used for cooking and lighting. Biogas is suitable to be developed in areas that have abundant biomass, especially in the centers of rice and livestock production in Central Java, East Java, South Sulawesi, Bali, and others.
Biogas generators are also suitable built for dairy cattle or poultry farm with cattle feces designing drainage into the digester.Housing complexes may also be designed to channel the sludge on biogas processing places together. Many developed countries that apply this system as part of efforts to recycle and reduce pollution and waste management costs. So it can be concluded that the biogas has a variety of benefits, which produces gas, preserve the environment, reduce pollution and improve hygiene and health, and producer of quality organic fertilizer.
To reap significant results, is necessary in a mass movement, directed, and planned include technology development, counseling, and mentoring. In the long term, biogas development movement can help save petroleum resources and forestry resources. Regarding the financing may be gradually transferred some fuel subsidies for the construction of biogas units. Through this way, may appeal the government to invite the community to jointly solve the energy problem can be partially realized.