Main components and content of biogas

The main component of biogas is methane. Biogas is composed of gases such as 50% -80% methane (CH4), 20% -40% carbon dioxide (CO2), 0% -5% nitrogen (N2), less than 1% hydrogen (H2), less than 0.4% oxygen (O2), and 0.1% -3% hydrogen sulfide (H2S). Due to the presence of a small amount of hydrogen sulfide in biogas, it has a slight odor. Its characteristics are similar to natural gas. When the air contains 8.6-20.8% (by volume) of biogas, an explosive mixture of gases will be formed.

The composition of biogas is influenced by various factors such as fermentation materials, fermentation conditions, and fermentation stages. Under normal circumstances, the proportion of methane in biogas produced from carbon rich raw materials is relatively low, while the proportion of methane in biogas produced from raw materials with high fat and protein content is relatively high; When the methane bacteria population is large and the environmental conditions are favorable for methane bacteria activity, the proportion of methane in the produced biogas is higher, and vice versa, it will be lower; In the initial stage of building a biogas digester, the proportion of methane produced is relatively low. As the number of methane bacteria increases, the proportion of methane also increases. In normal use of biogas, the methane content is above 50%. If it is below 40%, it can barely ignite, but it will extinguish when it leaves the flame.