For the drying of biogas, adsorption and condensation processes are the methods of choice.

Adsorptive gas drying processes:

This premise of this process is that water vapor adsorbs to specific compounds (including, for instance, silica gel and aluminum oxides). Using packed-bed adsorbers, these compounds are passed through the biogas as granulates, thereby removing water vapour from the gas.

The granulates must be regenerated after adsorption. Here it is important to note the difference between cold and warm regeneration process. If the biogas facility is to feed into the gas grid on a continuous basis, it is necessary to apply two separate packed-bed adsorbers so that one may be used when the other is regenerating. 

Condensation processes:

For this process the biogas is cooled, causing the water it contains to condense out. This process is above all intended for drying biogas for use in motor vehicles. The process does not meet specifications for biomethane preparation, however (after DVGW G260 and G262). For this reason, the process is designed only to prepare biomethane for feed-in to the grid.