The commingling problem

How mass balance handles it

An example, end to end

Physical commodities almost never stay separated. Cattle from many ranches become one stream of rendered tallow. Grain from hundreds of farms fills a single elevator.

If a measured reduction cannot survive that commingling, it dies at the first processing step — which is where mass balance earns its place on the rail.

Keeping every unit of commodity physically segregated by its environmental performance is impossible at scale and would defeat the point of a commodity market. You cannot run a global supply chain by tracking one specific animal’s molecules to one specific buyer. So the performance has to be handled as an accounting attribute that moves with the pool, not as a label glued to a single animal or bushel.

This is the same problem certified supply chains have solved for decades in other domains — the question is simply how to let a verified attribute travel through a mixed pool without inflating.

Mass balance tracks the credited volume in and never lets the credited volume out exceed it. If verified performance enters the pool for a given quantity, no more than that quantity of performance can leave attached to the outputs. The books stay balanced across every blend and transformation — hence the name.