Emission factor for anaerobic digestion feedstock and digestate for modelling and reporting

The emission factors below should be used when carrying out ammonia assessments, these factors are subject to change as further information becomes available, only the emission factors on the website at the time of your application will be considered valid.

The emission factor for anaerobic digestion will vary depending on the feedstock. For screening and modelling purposes you should use 0.0276 kg ammonia per kg of nitrogen in the feedstock for the digestate and 0.009 kg ammonia per kg of feedstock for the volume stored prior to digestion. 

Common feedstock nitrogen content are listed in the table below. 

Feedstock type Dry matter content of fresh matter (kg kg–1) N content of fresh matter (kg kg–1)

Municipal organic waste (a 

0.40  

0.0068  

Green waste (grass, etc.) (a 

Not available  

0.0046  

Food waste (food processing) 1)  

Not available  

0.0051  

Cattle slurry (a 

0.10  

0.0052  

Pig slurry (a 

0.06  

0.0048  

Cattle solid manure (b 

0.25  

0.0052  

Pig solid manure (b 

0.25  

0.0060  

Poultry manure (b 

0.50  

0.0175  

Maize silage (a)  

0.35  

0.0046  

Grass silage (a 

0.35  

0.0094  

Straw (a)  

0.86  

0.0051  

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