Co-processing is a refinery running bio feedstock through its existing units alongside crude oil. The renewable and fossil molecules come out inseparably mixed, so the renewable share is established by mass balance accounting rather than by physical segregation. For aviation this route is limited: ASTM D1655 Annex A1 permits co-processing at up to 5 %, well below the 50 % blending limit available to HEFA-SPK produced as a standalone fuel. The attraction is that co-processing needs no new plant, so it delivers renewable volume from existing refineries.
How it differs from a standalone renewable fuel
This distinction is worth getting right, because the two are frequently conflated in offers and they are not the same product.
- Standalone HVO or HEFA-SPK is made in a dedicated unit from bio feedstock only. The product is physically renewable throughout, and for aviation it blends into conventional jet at up to 50 % under ASTM D7566 Annex A2. See HVO and SAF.
- Co-processed fuel comes out of a conventional refinery that fed bio material in alongside crude. The molecules cannot be separated, so the renewable share is an accounting claim. For jet, co-processing is capped at 5 % under ASTM D1655 Annex A1.
- The commercial consequence: a co-processed barrel and a standalone barrel can both be genuinely renewable and still not be interchangeable, because the buyer's compliance framework may treat them differently.
The products
- Co-processed kerosene, into aviation, subject to the 5 % limit and to whether the buyer's scheme recognises co-processed material for the claim it needs to make.
- Co-processed naphtha, into steam crackers as renewable petrochemical feedstock or into gasoline blending. This competes directly with bionaphtha, and the difference is in the accounting rather than in the hydrocarbon.
- Co-processed diesel and gasoline components, into road fuel pools under national renewable fuel obligations.
What has to be agreed
The recurring problem is a seller who can state the renewable percentage but not the method or the scheme behind it. In co-processed material the accounting is not supporting documentation, it is the product, and a buyer's compliance team will treat a missing method as a missing product.
| Renewable share | The percentage claimed, and the method used to establish it. |
|---|---|
| Mass balance method | Energy, mass or carbon basis, and the accounting period. |
| Certification scheme | ISCC EU, ISCC CORSIA, REDcert or RSB, with co-processing explicitly inside the certified scope. |
| Scheme recognition | Whether the buyer's specific framework accepts co-processed material for the claim being made. |
| Bio feedstock | What went in, and its Annex IX status. |
| GHG saving | The figure on the proof of sustainability for the renewable share. |
| Specification | ASTM D1655 for jet, with Annex A1 governing co-processing; the relevant road or petrochemical spec otherwise. |
| Destination treatment | How the national scheme in the delivery market counts it. |
Frequently asked questions
What is co-processing?
A refinery running bio feedstock through its existing units alongside crude oil, so renewable and fossil molecules come out inseparably mixed. The renewable share is established by mass balance accounting rather than by physical segregation. Its attraction is that it produces renewable volume from existing plant without new investment.
What is the co-processing limit for jet fuel?
ASTM D1655 Annex A1 permits co-processing at up to 5 %. That is considerably lower than the 50 % blending limit available to HEFA-SPK produced as a standalone fuel under ASTM D7566 Annex A2, and it is the main technical constraint on the co-processed aviation route.
Is co-processed kerosene the same as SAF?
It is renewable aviation fuel, but it is not the same product as standalone HEFA-SPK and the two are not always interchangeable for compliance purposes. The limits differ, the accounting differs, and whether a buyer's framework recognises co-processed material for its specific claim has to be confirmed rather than assumed.
What is the difference between co-processed naphtha and bionaphtha?
Bionaphtha is the co-product of a dedicated hydrotreating unit running bio feedstock only. Co-processed naphtha comes from a conventional refinery that fed bio material in alongside crude, so its renewable share is a mass balance claim. Both can go to a steam cracker; which one a polymer producer can use depends on what its own customers require.
How is the renewable share verified?
Through mass balance accounting under a recognised voluntary scheme, with co-processing explicitly inside the certified scope. The method, whether energy, mass or carbon basis, and the accounting period both have to be stated. A renewable percentage without a stated method is not a usable claim.
Do all schemes accept co-processed fuel?
Not uniformly, and this is where deals fail. Recognition depends on the scheme and on the framework the buyer is claiming under. Establish what the end buyer actually needs to claim, and to whom, before agreeing anything else.
Who to ask about Co-processed naphtha & kerosene
Ask us. Co-processed volume to place or to source? Tell us the claim your buyer has to make and the scheme behind it. We answer the same working day, in English or Dutch, and there is no charge and no obligation for a market read or a second opinion on a specification.
You get Bart van den Brug directly, not a call centre and not a form that goes nowhere. We are an independent broker: we never take title, we do not trade our own book, and we are paid a commission only on business that actually concludes. That is why we will also tell you when the answer is no.
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Sustainable Commodities 3 B.V., Lemmer, the Netherlands
Last reviewed 09 August 2026 by Bart van den Brug, Sustainable Commodities 3 B.V. (KvK 99665042), Lemmer, the Netherlands. Regulatory references are given for orientation and are not legal advice; verify against the current Official Journal text before contracting.