As important renewable biogas in the futuer, ASPE Inc. Commercialized original technology of CH4 recovery system that recovers methane of high purity PSA. Biogas consists of methane, carbon dioxide, off-gas etc. and occurs at landfills, waste water treatment facilities, anaerobic digesters of sewage water or municipal waste water. The high purity of methane gas is used for fuel of vehicle and provided of natural gas.