Liquefied biogas refining technology, biogas is a mixed gas, its main components are methane (CH4) and carbon dioxide (CO2). Methane accounts for 60%-70%, carbon dioxide accounts for 30%-40%, and combustible gases such as hydrogen, carbon monoxide, hydrogen sulfide, oxygen and nitrogen. As long as the gas separation technology is used to convert carbon dioxide into dry ice for other industrial purposes, and zero-point compression liquefaction is used, the cost is not high, and the extracted combustible gas is compressed into a liquefied state. Steel cylinders are made to replace liquefied gas for residents to use.