On 18 July 2025, we published new information on the Australian Carbon Credit Unit (ACCU) Scheme project register. This is the last of 3 stages of updates to the register, which were made possible by the recent amendment to the Carbon Credits (Carbon Farming Initiative) Rule 2015.
The new information improves transparency around the operation and regulation of ACCU projects, and the delivery of ACCUs within the scheme. It reinforces the integrity of the scheme and contributes to Australia’s broader goal of accelerating carbon abatement.
Updates to the register
The register now includes these details for each project:
- the approach to determine carbon abatement
- where applicable, model start dates.
We’ve outlined how this new data offers further context to ACCU Scheme participation and administration.
This release also includes enforceable undertakings accepted in relation to projects, per the Carbon Credits (Carbon Farming Initiative) Act 2011. Although no enforceable undertakings are currently in effect for ACCU Scheme projects, the register links to previously completed undertakings.
Approaches to determining carbon abatement
Under the scheme, one ACCU represents one tonne of carbon dioxide equivalent (tCO2-e), sequestered or avoided. Projects that are eligible to generate ACCUs must have measurable outcomes that are quantifiable and verifiable.
Approaches to estimating carbon abatement for a project during each reporting period are defined by the project’s method. Most projects under the ACCU Scheme will either use measurements or models to determine carbon abatement. Some methods may rely on elements of both.
Measurement-based approaches
These involve collecting in-field data as the main input to abatement calculations. The data is then applied to equations in the relevant method.
The ACCU Scheme encompasses many measurement techniques, which are tailored to the requirements of each method. Below are some examples of measurement-based approaches by method grouping and type.
These methods involve collecting field data, such as the diameter of tree stems, and then applying allometric equations to estimate carbon stocks.
These methods involve measuring the quantity of methane destroyed by a combustion device, with reference to the:
- volume of landfill gas
- energy content of the landfill gas
- amount of electricity produced by an internal combustion engine.
These methods involve measuring the amount of soil organic carbon within soil cores taken from randomly allocated sites across the project and then measuring the change from baseline (pre-project) samples.
Model-based approaches
These use scientific models to estimate carbon abatement. Models are often chosen for vegetation methods where in-field data collection at a large scale may not be practical. Common models used include:
- Full Carbon Accounting Model (FullCAM) – for modelling carbon stocks in forest ecosystems
- Reforestation Modelling Tool (RMT) – for estimating tree and debris carbon pools in reforestation projects
- Savanna Burning Abatement Tool (SavBAT) – for estimating abatement in savanna fire management projects
Using a model lowers the cost of estimating abatement. Specific eligibility criteria, with regular checks and audits throughout the life of a project, ensure the model is only applied to appropriate areas of eligible land. This requires using multiple sources of evidence, including satellite imagery, aerial photography and field surveys. Methods also require evidence that modelled carbon stocks reflect the management activities and disturbance events that have occurred.
Projects using this approach must use the model and model version specified by the method. Projects declared under a modelled method may be allowed to use a newer model if one becomes available. In this case, transitional arrangements may be in place, allowing proponents to continue using the version of the modelling tool and guidelines that were current either:
- at the time the project was declared
- at the end of the first reporting period.
Description
Number of projects that have submitted an offsets report, and the FullCAM or RMT model/version used. Note that the data only includes projects that have submitted through the new Online Services platform. Projects that have yet to report are excluded. The forestry method family includes projects under Plantation Forestry 2017, Plantation Forestry 2022, and the New Farm Forestry 2014 methods. Projects that have been revoked are excluded.
Data collection
When crediting applications transitioned to the new Online Services platform, we began collecting structured data on the approaches to determining carbon abatement.
This data is only recorded where a crediting application for a project is submitted through Online Services. As more projects submit reports and applications through the new system, we will publish more detailed data on the approaches being used by individual projects.
Description
Proportion of registered projects by the combination of whether the project has submitted an offsets report which has been accepted, and whether data on the modelling or measurement approach is available. Projects that have been revoked are excluded.
Model start dates
When using FullCAM or RMT to quantify carbon abatement, a date must be specified to tell the tool when to begin the modelling. This is known as the model start date, and it applies to each carbon estimation area (CEA) within these projects.
Project timing
The timing of a model start date depends on the method – these dates are provided in the definitions of terms used in the project register, found in the Excel data download. Because modelling is conducted at the CEA level, many projects have multiple model start dates. If a project only lists one model start date, this same date applies to all CEAs in the project.
We’ve completed analysis below to show the relationships between project model start dates, crediting period start dates and project declaration dates. This can help explain how project timeframes differ between methods.
Find out more about timing within the broader project lifecycle in the ACCU Scheme project timelines.
For projects under methods which involve planting vegetation, such as the reforestation by environmental and mallee plantings methods, the model start date is the most recent day that trees and shrubs were planted in a CEA. Model start dates generally are within one year of the crediting period start date.
Planting may be deferred due to delays in receiving source materials and seedstock for the project or waiting for the correct weather and climatic conditions. This pushes the model start dates out from crediting period start dates and declaration dates. Under previous scheme arrangements, some projects were allowed to backdate their model start dates, resulting in those dates being before the crediting period start date and the declaration date.
The model start date for these projects is determined through remotely sensed imagery, expert advice about vegetation growth, and other evidence to pinpoint the date when a significant regeneration event occurred. This is generally in the baseline period, but growth pauses may be applied to reflect the suppression of this regenerating vegetation before the project commences.
For projects using the native forest from managed regrowth method, the model start dates are one day after the CEA’s last clearing event. As such, modelled regeneration can occur over an extended period before a project’s declaration date and crediting period start date.
Following a review of the method in 2019, the FullCAM guidelines for the method were updated. Projects registered after 31 March 2019 were required to have no more than 10 years of modelled regeneration before registration.
Seasonal influence
For most projects that plant vegetation to sequester carbon, the model start date is defined as the date when planting last occurred in the CEA. This planting date will be influenced by seasonal conditions.
In many parts of Australia where planting projects are located, mid-winter to early spring presents ideal conditions for tree planting, particularly native species. This is reflected in the model start dates for planting projects under the scheme.
Description
Number of model start dates by month for Reforestation by Environmental or Mallee Plantings and Plantation Forestry projects. Plantation Forestry includes projects under the Plantation Forestry 2017, Plantation Forestry 2022, and the New Farm Forestry methods. Projects that have been revoked are excluded.
Calculating net abatement
The model start date and the version of the model being used are only 2 of the many inputs required to assess carbon abatement outcomes of RMT and FullCAM projects. Other factors in calculating net abatement include:
- the size of the area of land being modelled
- any management events, such as fertiliser and weed control activities
- the nature and extent of disturbance events
- growth pauses (if applicable)
- the location of each CEA’s model point
- information on past management history used to determine the baseline model (business as usual scenario) of CEAs in the project (if applicable)
- emissions caused from implementing the project, such as from fuel use.