A carbon calculation can change substantially depending on whether it includes only direct facility emissions or also feedstock, transport, energy, avoided treatment, recovered products and final use. The boundary must therefore be defined before the result is interpreted.
Circular carbon concerns keeping carbon-containing materials in productive use and reducing unnecessary demand for new fossil carbon. It does not mean that every process recovering a carbon-containing output is automatically circular or climate-beneficial.
A process can recover carbon into a solid, liquid, chemical or fuel product without reducing overall greenhouse-gas emissions. Carbon avoidance depends on what the recovered carbon replaces, how long it remains in use, the energy required to recover it and its final fate.