Australian producers can calculate the emissions intensity and create Product Guarantee of Origin (PGO) certificates for making batches of biogas.
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 biogas produced through anaerobic digestion, including biogas that is:
- produced from the biological breakdown of biodegradable feedstocks in the absence of oxygen
- supplied as raw biogas, including biogas that may later be upgraded to biomethane.
Measuring biogas for certificates
For biogas, 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 biogas produced over a defined period that:
- is measured at the production gate (the point where biogas 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 only issue 10 certificates.
Producers may define separate batches where production processes or operating conditions differ.
Production modules and emission sources
Minimum production module
All biogas produced must include the anaerobic digestion production module, which covers:
- biological conversion of biodegradable feedstocks by micro organisms
- production of biogas in the absence of oxygen
- operation of equipment necessary to produce biogas, including digesters and associated systems.
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 biogas, they must still be included when they are used.
Optional modules may include:
- 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 biogas production
- all emissions sources that occur for the batch must be monitored and reported.
Production emission sources
Depending on how the biogas 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
- digestate storage.
Only emissions sources that occur for the batch need to be reported.
Delivery modules and emission sources
Biogas produced may include delivery modules, each with their own associated emission sources.
Emission sources for the delivery of biogas via vehicle transport may include:
- fuel supply and combustion
- electricity supply and use
- synthetic gas use.
Emission sources for the delivery of biogas via pipeline transport may include:
- electricity supply and use
- fuel supply and combustion.
Emission sources for the storage of biogas may include:
- electricity supply and use
- steam supply
- synthetic gas use
- fuel supply and combustion.
Delivery related losses
Loss rates may apply during transport and storage of biogas where delivery modules are used. 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 represents the proportion of biogas 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 biogas 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 biogas (for example, agricultural waste, food waste or wastewater sludge)
- percentage (by mass) of input feedstock derived from energy crops (where applicable).