24 Nov 2022

Explainer series | Biofuels 202 - Book and Claim

Posted in: Reducing emissions

Explainer series: Book and Claim models for GHG emissions

Book and Claim models are a part of the mix for emissions reductions in the aviation sector. Source: Microsoft Stock Images

Key points

- Book and Claim models help account for the benefit of reduced emissions. These benefits are transferred to an end user. This model offers an alternative way of attributing Greenhouse Gas (GHG) emissions reductions to another party, separating the benefits from the physical flow of lower emissions goods. It is well established in electricity markets, and is in its infancy for other energy sources such as Sustainable Aviation Fuels (SAF).

- This approach is intended to provide a mechanism to scale up the use of lower emissions energy sources and overcome market barriers such as cost (Sustainable Aviation Fuel is said to be 2-8 times more expensive than conventional Jet Fuel), and geographic separation. This separation occurs between the physical location of the energy source and the buyer seeking to account for the reduced GHG emissions of that source.

- Book and Claim models for energy sources such as SAFs, biofuels, and gas, are still being established. Hence, acceptance of these models by GHG emissions measurement standards and other relevant initiatives is evolving. Wider environmental and social impacts must also be considered. We can expect change around practises and standards concerning these models, and Toitū will continue to monitor and communicate these changes.

What are Book and Claim models?

Book and Claim models are attracting increasing interest as a tool to account for Greenhouse Gas (GHG) emissions reductions across supply chains. This ‘chain of custody model’ records those benefits (on the books, so to speak) of GHG attributes to be claimed by other parties. Hence the name, Book and Claim. For example, the GHG emissions attributes of using Sustainable Aviation Fuels (SAFs) can be transferred separately as a unit via a dedicated registry. Instances of where these models are being used include the renewable electricity sector (via Renewable Energy Certificates), Round Table on Responsible Soy, Roundtable on Sustainable Palm Oil, and Green Palm. Figure 1 provides an illustration of key features of a Book and Claim model.

For renewable liquid fuels, known models include:

The RSB model approach is currently piloting Book and Claim in collaboration with participants including Singapore Airlines and AirBP. This includes a published draft manual and development of an electronic registry to support the uptake of Book and Claim at a larger scale. RSB’s Book and Claim model is also applicable to shipping, with Maersk also piloting the model. For renewable gas, the New Zealand Energy Certificate System is in development to formalise the benefits of these emissions reductions. For renewable electricity, see our position on market-based renewable electricity.

Figure 1: Illustrative description of key features of book and claim, Sustainable Aviation Fuels (SAF) context. Source: Book and Claim - RSB

Benefits of Book and Claim models for reducing emissions

Looking at the benefits, the main intent of Book and Claim models is to efficiently scale up the use of low emissions energy sources. Using SAF as an example, here are four benefits for such a system:

1. Share the cost premiums across users: SAF costs more than regular fossil fuels. Sharing the premium across users helps increase the number of purchases, which amplifies SAF demand and encourages further investment in production. Over time, this should lead to increased supply, at reduced cost.

2. Airline and location independent: the Book and Claim system allows corporates to source SAF based on their total aviation footprint in one transaction, rather than sourcing through each airline individually. This means that SAF can be sourced for flights with airlines or out of airports that do not have SAF supply available, thus enabling corporates to effectively contribute to scaling up SAF volumes and use.

3. Achieve your desired reduction: any volume of SAF can be purchased through a Book and Claims system. This could include 100% of fuel needs or meeting an emissions reduction target, without worrying about technical limitations such as blending limits.

4. Minimise supply chain emissions: SAF is produced in very limited volumes and only in select locations globally. To optimise the sustainability of SAF, it is best to keep the supply chain as efficient as possible. By entering SAF into the fuel system of an airport close to the production facility, the supply chain’s GHG emissions are minimised.

Limitations and robustness of Book and Claim models

Drawing from Toitū’s thoughts on Electricity Certificates, similar concerns might be applicable to other Book and Claim models. These include:

  • Being able to report energy source emissions as zero or low emissions discourages demand efficiency measures (eg using more fuel efficient transportation and/or trip planning to reduce travel demand).
  • It is potentially misleading for an organisation to report zero emissions when the physical energy mix they consume or their business model is emissions intensive.
  • The Book and Claim models need to be designed in a way that achieves increased use of renewable energy sources, both in speed and volume of uptake.
  • Having sufficient transparency and traceability across the full supply chain (e.g., having robust registries that hold the attributes and show clear usage and cancellation to avoid double use of the same attribute).

The acceptance of Book and Claim models in the context of organisation and/or product level GHG emissions accounting is still settling. Our understanding is that several Book and Claim models are liaising with well-known GHG measurement standards such as ISO14064-1:2018, and the GHG Protocol to establish alignment and recognition of their models. For product level accounting, ISO14067-1:2018 mentions market-based instruments as being an acceptable component of the measurement, which would include Book and Claim.

In addition to the GHG measurement standards, Science Based Targets initiative (SBTi) also play a part (see our Toitū resource for further information here). This is a global initiative that enables organisations to set GHG reduction targets grounded in science, and in line with a 1.5°C world. SBTi currently accepts use of electricity market-based instruments, including Book and Claim model energy certificates (or equivalent). However, at the time of writing, for Book and Claim models covering Sustainable Aviation Fuels (SAF), SBTi is yet to decisively conclude acceptance of these. It does acknowledge that Book and Claim is a practical option in the Airline context:

“The use of SAF certificates traded on a marketplace/exchange or carbon credits/offsets cannot at this time be counted towards a science-based target due to potential inconsistencies with GHG protocol guidance” “…that use of a “Book-and-claim” method, whereby the environmental attributes associated with the fuel are decoupled from the physical supply, will be most practical.” - SBTi

The ISO standard on GHG emissions from transport chain GHG emissions is currently in development, and it will be interesting to see what reference is made to Book and Claim models once released for use.

Practical application of Book and Claim models

As noted previously, there is still some settling required on accounting approaches under the relevant GHG measurement standards. If such models are accepted, a conservative and transparent accounting approach is needed. This would involve dual reporting of gross emissions for the physical energy consumed, alongside attribute related emissions from the Book and Claim system. For example, an end user might physically travel on a flight using 100% conventional fossil fuel, emitting two tonnes CO2e. These emissions would be reported as the physical gross emissions. However, the end user has purchased sufficient SAF certificates to cover their energy demand of the same flight. The SAF certificates confirm zero emissions, and hence this would be reported as zero emissions for the owner of the certificate, under a Book and Claim approach. This is consistent with the approach for reporting location-based vs market-based electricity under Scope 2 / ISO Category 2 organisation inventories.

Due diligence is also required in checking that the attribute (or certificate) purchased is cancelled (or equivalent) on the Book and Claim registry after that claim has been used. This is to maintain integrity in the system by ensuring the same certificate is not double counted or sold on to another buyer.

Examples of uptake by end user organisations

A number of examples exist of organisations using, or intending to use, Book and Claim models as a method to reduce their GHG emissions:

Many of these companies have validated targets under the SBTi, and so one can anticipate Book and Claim attributes purchased can be used for demonstrating emission reductions to achieve SBTi targets.

Additional considerations

Any low emission energy source used as an alternative to emission-intensive fossil fuels needs to be considered in the full context of ‘Well to Tank (WTT)’ GHG emissions (referred to also as ‘upstream’ or ‘cradle to gate’ emissions in Lifecycle measurement terminology). WTT refers to all GHG emissions from production, transportation, and distribution of a fuel used to power a vehicle. This is applicable regardless of whether the energy source is, or is not, under a Book and Claim system. Consideration also needs to be given beyond GHG emissions, to the wider environmental and social impacts. For example, for biofuels this includes biodiversity, water resources, and competition for food (first generation feedstocks vs second generation feedstocks). Refer to our explainer on Biofuels for further information on this topic.

Energy sources within a Book and Claim system should have adequate quality criteria to address both WTT emissions and relevant wider environmental and social impacts. An example of this is the RSB model, which includes a certification programme on sustainability of the fuel. It deploys 12 key Principles for the sustainable production of fuels and products, including:

  • Legality
  • Planning, monitoring and continuous improvement
  • GHG emissions
  • Human and labour rights
  • Local food security
  • Conservation
  • Land rights

The International Sustainability and Carbon Certification (ISCC) is another example of a sustainability certification system for feedstocks, with certifications catering for different markets.


Book and Claim models have been developed for various renewable energy sources, which enable an end user to make market-based accounting measurements. These models can efficiently scale up and amplify the use of low emissions energy sources in markets to overcome barriers such as cost (relative to the ‘conventional’ energy source), and geographic separation (between physical location of the energy source and the buyer seeking to account for the GHG attribute). Book and Claim models for other energy sources such as sustainable aviation fuels, biofuels, and gas, are in the early stages of establishment, while electricity models are well established.

Toitū will continue monitoring the development of Book and Claim models, and, in principle, is open to the use of them in emissions accounting. This is subject to settling of acceptance by major GHG emission measurement standards, such as ISO and GHG Protocol, and other relevant initiatives, such as SBTi.


Book and Claim models

Technically speaking, ‘book and claim’ is a chain of custody model that allows to de-couple specific attributes, like for example the environmental benefits, from the physical product and to transfer them separately via a dedicated registry in the form of a ‘Book & Claim Unit’. This approach has been already successfully implemented in the renewable electricity sector

Book and Claim for RSB SAF

Book & Claim enables customers (airlines and their corporate partners) to purchase SAF without being geographically connected to a SAF production site. It enables them to purchase “SAF Credits” in addition to their conventional fuel, paying the premium for SAF to the SAF producer or supplier, who then sells their SAF as conventional fuel without any sustainability claims.

All transactions are recorded in a timely manner in a Book & Claim Registry, which is the database collecting and storing all Book & Claim transactions and related product and sustainability data

Chain of CustodyA process that tracks the movement of evidence through its analysis lifecycle by documenting each entity who handled the evidence, when it was collected or transferred, and the purpose for the transfer
GHG Protocol Corporate StandardThe GHG Protocol Corporate Accounting and Reporting Standard provides requirements and guidance for companies and other organizations preparing a corporate-level GHG emissions inventory
GHG Protocol Scope 2 StandardThe [GHG Protocol] Scope 2 Guidance standardizes how corporations measure emissions from purchased or acquired electricity, steam, heat and cooling
GHG Protocol Scope 3 Supply Chain StandardAs defined by the GHG Protocol: The ‘Scope 3 Standard’ provides a methodology that can be used to account for and report emissions from companies of all sectors, globally
ISO14064-1:2018The international standard Greenhouse gases – Part 1: Specification with guidance at the organizational level for quantification and reporting of greenhouse gas emissions and removals issued by the International Organization for Standardization
ISO14067-1:2018This document specifies principles, requirements and guidelines for the quantification and reporting of the carbon footprint of a product (CFP), in a manner consistent with International Standards on life cycle assessment (LCA) (ISO 14040 and ISO 14044)
Renewable energy, including electricity, gas, liquid fuelsRenewable energy is energy derived from natural sources that are replenished at a higher rate than they are consumed. Sunlight and wind, for example, are such sources that are constantly being replenished. Renewable energy sources are plentiful and all around us. Fossil fuels - coal, oil and gas - on the other hand, are non-renewable resources that take hundreds of millions of years to form. Fossil fuels, when burned to produce energy, cause harmful greenhouse gas emissions, such as carbon dioxide
Science Based Targets Initiative (SBTi)The Science Based Targets initiative (SBTi) drives ambitious climate action in the private sector by enabling organizations to set science-based emissions reduction targets
Supply chainA network of organizations (e.g., manufacturers, wholesalers, distributors and retailers) involved in the production, delivery, and sale of a product to the consumer
Well to TankAll greenhouse gas emissions from the production, transportation, transformation and distribution of the fuel used to power the vehicle