Any organic matter can produce RNG: food waste, manure, crop residues, forestry residues, etc. many municipalities have passed rules to divert food waste from going to landfill, since this would produce methane and other GHGs when decomposing. So the waste either goes to composting or to one of these digesters to produce natural gas. We produce an insane amount of food and farm waste, this is putting it to good use. It’s renewable because we are constantly producing this waste. Combusting methane does produce CO2, but compared to the CH4 that would be created from this waste breaking down in a landfill, this is many many times less harmful for the environment. When people talk about reducing your carbon footprint it’s not just CO2, there’s carbon in methane too (CH4).