4. Current CO2 Utilization Pathways and Their Carbon-Retention Characteristics.
| application category | CO2 consumption (Mt/yr) | technology type | key products | carbon permanence | permanence score (P) | CVR implication |
|---|---|---|---|---|---|---|
| , enhanced oil recovery (EOR) | ∼80 | direct use (injection) | oil extraction | low (re-emitted later) | 1 | high utilization volume, limited long-term carbon retention |
| urea/fertilizer production | ∼130 | chemical conversion | urea | low-medium | 2 | very large utilization volume and established market, limited long-term carbon retention |
| synthetic fuels (e-fuels) | <10 | thermo-/electrochemical | methanol | low (combustion releases CO2) | 1 | provides carbon recycling and fuel value, but carbon is rapidly returned to the atmosphere |
| chemicals & polymers | ∼10–20 | catalytic conversion | methanol, polymers, carbonates | medium | 3 | intermediate value potential, carbon lifetime depends on product structure and end-of-life treatment |
| , building materials (concrete) | ∼5–10 | mineralization | carbonated concrete | high (long-term storage) | 4 | strong retention potential and material value generation |
| − carbon materials | <1 | advanced conversion | CNTs, graphene, nanomaterials | high | 5 | very high carbon value retention and high value products, limited market |
a
Permanence score (P) is an ordinal screening scale ranging from 1 to 5, developed to comparatively assess the expected duration of carbon retention across different CO2 utilization pathways. A score of 1 represents relatively short-term carbon retention, whereas a score of 5 represents the highest expected long-term retention potential. The scores do not represent measured carbon lifetimes or specific durations; they provide a comparative ranking based on the carbon fate and permanence descriptions reported in the manuscript.