Carbon balance, not carbon ratio: how to read CDR efficiency claims
Most CDR efficiency claims are framed as a ratio. They should be framed as a balance. A ratio of 1.1 — 100 tonnes emitted across the lifecycle to capture 110 tonnes — is a vanity metric. The number that matters is the net balance: gross capture minus embodied plus operational emissions. That is what we mean when we say a pathway is “85% net.” For every 100 tonnes of CO2 pulled out of the air or fixed in stable form, 85 tonnes survive after you subtract everything the project emitted to make those 100 tonnes happen. The 15 tonnes you are losing went into making steel, running compressors, trucking rock dust, or heating a sorbent. That is what credible buyers should pay for: the 85, not the 100. The credible registries already refuse to issue credits for anything else. ...