How are emissions from existing use or fate (e_exuse) and emissions from fuel in use (e_u) connected? Do they have to be the same?

Eex-use and eu are separate terms within the GHG emissions calculation methodology for RFNBOs and RCFs. According to the DR (EU) 2023/1185:

• “Emissions from existing use or fate include all emissions in the existing use or fate of the input that are avoided when the input is used for fuel production. These emissions shall include the CO2 equivalent of the carbon incorporated in the chemical composition of the fuel that would have otherwise been emitted as CO2 into the atmosphere.”

• “Emissions from combustion of the fuel refer to the total combustion emissions of the fuel in use.”

Fuel in use emissions must include CO2 and non-CO2 combustion emissions from N2O and CH4.

e_ex‑use and e_u can be numerically similar when the carbon incorporated into the RFNBO would otherwise have been fully oxidised and is later released during combustion; however, they are derived from different system boundaries and must be calculated independently.

You cannot claim more e_ex-use than the eligible carbon incorporated into the fuel. Excess CO2 that is not incorporated gives no extra e_ex-use.

If excess CO2 is emitted, vented or leaked during processing, it should be accounted under e_p, because processing emissions include direct atmospheric emissions, waste treatment and leakages.

If the eligible CO2 input is fully incorporated into the RFNBO fuel output, and the carbon in the final fuel is fully oxidised to CO2 during use (combustion), with no losses, venting or non-CO2 combustion emissions, then the incorporated-carbon component of e_ex-use may equal eu.