What is biomass co-processing?

Co-processing is defined as the simultaneous processing of a base feedstock (typically fossil crude oil) with a biogenic feedstock (bio-oils, such as vegetable oils, used cooking oil, pyrolysis oil, etc.). Co-processing is typically performed in a petroleum refinery setup, but can also occur in other types of installations.

The benefit of co-processing is that fossil feedstock can (incrementally) be replaced with renewables. This introduces a certain renewables share into the product slate of the co-processing facility, while achieving the same product quality as an installation operating solely on the base feedstock. To determine the resulting share of renewables in each product of the facility, several different calculation methods can be used. These methods may potentially lead to different outcomes. Therefore, the European Commission published a Delegated Regulation to the Renewable Energy Directive (RED) to set out clearly defined rules (see PDF here) on the calculation of the resulting renewables share for products obtained via co-processing facilities. It should be noted that all RED-compliant biofuels are eligible for co-processing under this regulation.
The regulation was processed via the Better Regulation portal of the European Commission (open in new tab).

• All approaches must be verified and calibrated with radiocarbon (¹⁴C) testing results.
• Mass balance must take impurities and moisture content of biomass into account, as well as losses of biogenic material to wastewater, off-gases or solid residues.
• Energy balance assumes that all bioenergy input equals all bioenergy output. The allocation of bioenergy across the product slate must reflect the results from radiocarbon (¹⁴C) testing.
• Yield method determines (in a representative pilot plant) impacts on product yields by introduction of bio-feedstock into the refinery.

• In the atmosphere, cosmic radiation converts nitrogen (¹⁴N) to radioactive carbon (¹⁴C) – which is an unstable isotope of the typical, stable, non-radioactive carbon (¹²C).
• Radioactive carbon (¹⁴C) is taken up via CO₂ by plants during photosynthesis. That way, radioactive carbon (¹⁴C) enters the food chain and can be found in all biomass on Earth.
• When animals die or plants decompose, they stop receiving new inputs of fresh radioactive carbon (¹⁴C). In animal or plants remains, radioactive carbon then slowly reacts back to nitrogen (14N), with a half-life of 5730 years.
• Fossil resources stem from biomass decomposition and have taken millions of years to form. Therefore they practically show no remaining ¹⁴C. They mostly consist of ¹²C.
• Measuring the ¹⁴C content in a mixed sample of fossil fuels and biofuels can thus enable to establish, which share of the material’s carbon is of biogenic origin and which share is of fossil origin.