What is the difference between biogas and biomethane?
Biogas is a mix of carbon dioxide (CO2) and methane (CH4) which can contain various other gases like hydrogen sulphide (H2S), nitrogen (N2), oxygen (O2), hydrogen (H2), and Volatile Organic Compounds (VOC). This biogas can be upgraded into biomethane (the CH4 content of the biogas) by using different processes like water scrubbing, amines scrubbing, membranes, Pressure Swing Adsorption (PSA), and cryogenic distillation. All these methods of upgrading require a compressor to push and increase the pressure of the biogas from the digester to the upgrading process from usually atmospheric pressure up to 15 barg.
This can be done by using the Atlas Copco GG screw compressor. Once upgraded, the biomethane can be reinjected into the gas grid by eventually using an additional compressor, depending on the gas grid pressure. Using the same accounting principles of green electricity, biomethane can be taken from the grid to fill vehicles on a CNG refueling station, using compressors with outlet pressure up to 250 barg. This can be done with Atlas Copco’s CU or BBR CNG piston compressors.
When upgraded to biomethane, biogas can be used as fuel in vehicles that run on compressed natural gas (CNG) or injected into the natural gas grid.
