Over the past few years, the chemical industry has begun to use the mass balance approach to track the flow of circular and/or bio-based materials through the value chain and attribute it separately in bookkeeping.

The mass balance approach is an important milestone on the journey toward a circular economy. Because bio-based feedstocks are often mixed with other materials during manufacturing, it’s not always practical or feasible to physically separate recycled content and track it separately.

Other approaches often freely attribute circular or bio-based feedstock inputs to one or more outputs.

Alternatively, the mass balance approach measures the amount of circular and/or bio-based feedstocks at various points throughout the production process and segregates it in bookkeeping. Each of the final outputs then have a more accurate measure of its share of circular and/or bio-based feedstock versus fossil feedstocks.

The mass balance approach gives a more accurate measure of the make-up of an output or final product. When it’s clear what share is circular and/or bio-based feedstock, it’s possible to work toward increasing that share in the production process and attributing it on an equivalent basis.

Also, those using the mass balance approach can make more credible claims about the sustainability of their final products.