Australian producers can calculate the emissions intensity and create Product Guarantee of Origin (PGO) certificates for making batches of biomethane.
To do this, you’ll need to:
- identify and understand emissions sources
- understand co-products and losses
- provide your quantity information.
We’re developing calculators that will help you calculate emissions intensity using the supplied quantity information.
This applies to biomethane produced through upgrading biogas, including biomethane that is:
- refined and purified from biogas to meet natural gas specifications
- supplied as a substitute for natural gas for use in transport, industry or energy applications.
Measuring biomethane for certificates
For biomethane, the functional unit is 1 gigajoule (GJ) of methane, measured as a higher heating value. Each PGO certificate represents one whole gigajoule of methane.
A batch is the quantity of biomethane produced over a defined period that:
- is measured at the production gate (the point where biomethane is ready for delivery)
- has a single, consistent emissions intensity.
We only issue certificates for whole gigajoules. For example, if a batch contains 10.9 GJ, we will issue 10 certificates.
Producers may define separate batches where production processes differ. For example, where biomethane is produced using different feedstocks or operating conditions.
Production modules and emission sources
Minimum production module
All biomethane produced must include the biogas upgrading production module. This covers:
- refining and purifying biogas to remove carbon dioxide, moisture and other impurities
- upgrading biogas so it meets specifications suitable for use as a natural gas substitute
- operating equipment necessary to upgrade biogas to biomethane.
This is the minimum module and must be included in every eligible batch.
Optional production modules
Optional modules may apply when additional processes are used. Although these activities aren’t required to make a batch of biomethane, they must still be included when they are used.
Optional modules may include:
- anaerobic digestion
- feedstock transport
- feedstock pre-treatment
- intermediate storage tanks
- intermediate transport
- gas conditioning.
If optional modules are included, emissions from these activities must be accounted for as part of the biomethane production. All emissions sources that occur for the batch must be monitored and reported.
Production emission sources
Depending on how the biomethane is produced, emissions may need to be accounted for from the following sources:
- electricity supply and use
- fuel supply and combustion
- feedstock supply
- steam supply and use
- synthetic gas use
- production fugitive emissions.
Only emissions sources that occur for the batch need to be reported.
Delivery modules and emission sources
Biomethane produced may include delivery modules, each with their own associated emission sources.
Emission sources for the delivery of biomethane via vehicle transport may include:
- fuel supply and combustion
- electricity supply and use
- synthetic gas use.
Emission sources for the delivery of biomethane via pipeline transport may include:
- electricity supply and use
- fuel supply and combustion.
Emission sources for the storage of biomethane may include:
- electricity supply and use
- steam supply
- synthetic gas use
- fuel supply and combustion.
Delivery related losses
A loss rate may apply during delivery where biomethane is transported or stored.
In these cases, loss rates are calculated using a module-specific loss method, based on the difference between total inputs and outputs over a defined period. This is expressed as a proportion of methane lost during transport or storage.
The method used to account for losses during methane delivery depends on the delivery pathway.
Single access pipelines use direct measurement at the delivery point, while other pipelines apply a pipeline specific loss factor under the module specific loss method.
For vehicles, either direct measurement or a vehicle specific loss factor may be used.
Storage vessels must apply a storage specific loss factor under the module specific loss method.
Where methane is delivered directly with no delivery module, no loss factor applies and the delivered amount is the same as the quantity at the production gate. For example, direct transfer to a customer or shared pipeline.
Attributes shown on certificates
As well as the standard attributes listed on PGO certificates, certificates for biomethane include the:
- methane content of the batch (expressed as a percentage of total volume)
- moisture content of the batch (expressed as a percentage of total volume)
- type of feedstock used to produce the batch
- percentage (by mass) of input feedstock derived from energy crops (where applicable).