Meaning
A mass balance accounting procedure distributes recycled or bio-based feedstock credits across co-products while excluding the portion of output used as energy. When chemical recycling plants process mixed plastics, a portion of the incoming material always becomes fuel gas or heavy oil used for process heat. Through fuel exempt proportional allocation, operators ensure that only the portion converted back into polymer resins or chemical intermediates receives recycled certification.
This ensures trade audits remain transparent.
Accounting Method
Feedstock mass entered into a cracker does not yield pure ethylene or propylene directly. Proportional distribution rules assign the certified circular mass only to the fractions that leave the boundary as polymer precursors. High-temperature pyrolytic conversion processes demand a lot of energy.
Since process fuel cannot be sold as plastic, it is excluded from the certified allocation. This keeps the audit trails aligned with chemical realities.
Material Yield
A processing plant running this calculation reduces the risk of credit inflation. Certified mass enters the plant ledger, and non-certified energy loops consume their proportional share. In practice, this keeps the value of certified polymers stable.
Regulatory Compliance
Certification schemes such as ISCC PLUS enforce these boundary rules to prevent double counting. Some regions require verification before polymers can be sold as food-contact grades. Non-compliance results in the forfeiture of circular credits.
