Compressed Bio Gas Storage Process

 High-Pressure Biogas Storage

The typical composition of raw biogas does not meet the minimum CNG fuel specifications. In particular, the CO2 and  sulfur content in raw biogas is too high for it to be used as vehicle  fuel without additional processing. Biogas that has been upgraded to biomethane by removing the H2S, moisture, and CO2 can be used as a vehicular fuel.

Biomethane is less corrosive than biogas, apart from being more valuable as a  fuel. Since production of such fuel typically exceeds immediate on-site  demand, the biomethane must be stored for future use, usually either as  compressed biomethane (CBM) or liquefied biomethane (LBM).

Two of the main advantages of LBM are that it can be transported relatively easily and it can be dispensed to  either LNG vehicles or CNG vehicles. Liquid biomethane is transported in  the same manner as LNG, that is, via insulated tanker trucks designed  for transportation of cryogenic liquids.

Biomethane can be stored as CBM to save  space. The gas is stored in steel cylinders such as those typically used  for storage of other commercial gases. Storage facilities must be  adequately fitted with safety devices such as rupture disks and pressure  relief valves.

The cost of compressing gas to high  pressures between 2,000 and 5,000 psi is much greater than the cost of  compressing gas for medium-pressure storage. Because of these high  costs, the biogas is typically upgraded to biomethane prior to compression.