What is renewable natural gas?
Renewable natural gas (RNG) is
How should you report RNG in your greenhouse gas inventory?
This is still an emerging and developing field, and the specific data entry may depend on the source of your RNG.
Our general recommendation for renewable natural gas is to enter it as a scope 1 biogenic source. For SIMAP, this means entering a custom biogenic CO2 emissions factor and zeroing out the standard CO2 emissions factor on the Data Entry tab > Emission Factors page. RNG should be entered as biogenic CO2 because there are still emissions being released when RNG is combusted, but those emissions fall in the biogenic category. Biogenic emissions are considered carbon neutral and should be reported separately from your net greenhouse gas emissions.
We have been considering how to address the full lifecycle of renewable natural gas, since its generation can sometimes mean that emissions were avoided. If this upstream emissions avoidance can be verified, then it can be entered as an offset.
An institute should only enter RNG as biogenic if it retains the associated environmental attributes (e.g., RINs). If an institute sells the environmental attributes for RNG, then they unfortunately would no longer be able to claim those environmental attributes. This is because another entity could claim those environmental attributes, and there would be a risk of double-counting. If an institute would like to claim the environmental attributes, then we suggest that they retain them and do not sell them.
What are these recommendations based on?
We have based our interpretation on the most similar concept in the GHG Protocol – RECs for scope 2 purchased electricity. Since RECs and environmental attributes for RNG are both market transactions that have environmental attributes associated with them, we expect that the guidance for RNG will be comparable to RECs. We have also reviewed several working papers prepared by the World Resources Institute (an organization that prepares the GHG Protocol), including the following: