Key points — if you have 30 seconds
- 01Chain of custody (CoC) is the documented trail of a batch of energy from source to end use, including who had it in their custody and when.
- 02There are four common models — identity preserved, segregation, mass balance and book-and-claim — with increasing distance between molecule and claim.
- 03A usable chain record contains at least origin, quantity, date, the parties involved, sustainability characteristics and the certification scheme.
- 04RED III, CSRD and tender criteria shift the burden of proof to the user; "the supplier said so" is no longer proof.
§ 01The definition, without the jargon
Chain of custody — literally a "chain of custodians" — is the documented trail that a batch of energy leaves from the source to the point where it is used. At every transfer it is recorded who took over the batch, when, in what quantity and with which characteristics. The term comes from the world of evidence and reached the energy market via sustainable feedstocks and fuels. [1]
The aim is simple: if someone at the end of the chain asks "where does this come from?", the answer should not be an opinion but a record. For renewable gas that is essential, because the molecule itself gives nothing away about its origin — see what renewable gas is and is not.
§ 02Four models, increasing distance
Not every chain of custody is equally strong. Certification schemes distinguish four models, with an ever greater distance between the physical molecule and the claim that rests on it: [1]
- Identity preserved. The consignment stays physically separate from source to use and remains traceable to one specific origin. The strongest model, and the most expensive.
- Book-and-claim. The certificate is fully decoupled from the physical product. The claim travels administratively; the molecule goes its own way. The weakest model when it comes to physical displacement.
Which model is acceptable depends on who is asking. For a national target, mass balance may be enough. For a client who wants to know what was burnt on their own construction site, the bar sits closer to segregation or identity preserved.
§ 03What a good chain record contains
A chain of custody that holds up in an audit is not a letter from the supplier but a set of data per consignment. As a minimum: [1] [2]
- Origin — the production site or source, with a unique marker.
- Quantity and date — how much was transferred and when.
- Parties — who took over the consignment, with the corresponding certificate numbers.
- Sustainability characteristics — feedstock type, the model used and the greenhouse gas data that travel with the consignment.
- Certification scheme — the recognised scheme under which the chain was audited, and where the registration can be found.
If one of these elements is missing, there is a gap in the chain. And to an auditor, a chain with a gap is not a chain.
Proof is not an attachment to the delivery. It is the delivery.
The principle behind the Proof Trail§ 04Why it weighs so heavily now
Three developments have turned chain of custody from a nice-to-have into a requirement. First, RED III requires renewable fuels to be tracked through mass balance and — for gaseous fuels — registered in a European database. [2] Second, the CSRD requires large companies to report and substantiate their energy consumption and mix; the auditor tests that substantiation. [3] Third, contracting authorities increasingly include demonstrability as an award or performance requirement, precisely because paper claims have failed in the past.
The result is a shift in the burden of proof: it is not the supplier but the user who has to be able to show what they used. Anyone without that proof per consignment carries the risk.
§ 05How Powercrumbs applies it
In the Powercrumbs chain, every consignment of gas starts with an origin marker at the source, that marker travels along via the hub and the delivery on site, and it ends up in a file per project — the eight steps of the Proof Trail. The model is deliberately kept close to the physical molecule: the gas used at your site is the gas whose origin has been logged. How the bookkeeping behind it works is covered in the article on mass balance.
§ 06References
- ISCC — ISCC EU system document on chain of custody and the permitted models (segregation, mass balance) for sustainable feedstocks and fuels.Certification scheme · recognised by the EUPrimary
- European Union — Directive (EU) 2023/2413 (RED III) — requirements for mass balance, certification and the Union database for tracking renewable fuels.Legislation · primaryPrimary
- EFRAG — European Sustainability Reporting Standards (ESRS E1) — reporting on energy consumption and mix and the substantiation behind it under the CSRD.Reporting standard · in forcePrimary
Full references (titles, dates, links) to follow.
About the author
Pieter Founder · product and engineering
Pieter founded Powercrumbs and works on product and engineering: the chain from source via hub to delivery on site.
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