Rotting organic matter creates methane.  Sending organic matter to landfill or composting in traditional ways (when there is a smell) - creates methane.

Using a Subpod with an aerobic environment (lots of oxygen) - does not emit methane.  

Methane is 18 times worse than CO2.  The aerobic environment in Subpod is created using the airflow panels at the top of the Subpod.  Also, by using the aerator when organic waste is added to the Subpod, it mixes oxygen through the Subpod - aerating the system. 

The microbes that live in an oxygen-rich environment don't create methane like the anaerobic microbes creating the smelly, methane-rich gases. 

When organic matter is buried in a landfill rather than properly composted, it breaks down anaerobically, generating lots of methane and very little CO2.   (To give you an idea of how much methane is generated, approximately half of all the atoms in organic waste molecules are carbon atoms and as much as 50% of this carbon is broken down into methane gas ( CH4 ) under anaerobic conditions.  Methane traps far more heat than CO2.  So as to compare the impact directly, greenhouse gases other than CO2, like methane are converted to CO2 equivalents, with the value dependent on the gas’s heat-trapping ability.   In a 20 year time scale methane is 86 X more potent than CO2 or 26 - 28X more potent over a 100 year scale.  Both scales are used to generate equivalents which is why you see both values quoted for methane.  Since it survives in the air on average for 10 years, the 20 year scale is a more accurate way to measure its impact.  This explains how 15kg of organic waste generates over 2 metric tonnes of CO2 equivalents per year.