How our figures are checked
Every CarbonKeel figure comes from a fixed calculation that anyone can repeat. Here it is tested three ways: against the verifier’s own figure for every ship in the EU register, against a published reference case, and against worked examples done by hand.
1 · Reference cases, worked out now by the live calculation
| What | Case | CarbonKeel | Reference | Match |
|---|---|---|---|---|
| Poseidon Principles trajectory Technical Guidance v5.2, worked example | Bulk carrier, 80,000 DWT, 2024 | 3.88 and 3.66 g CO₂e/dwt-nm | 3.9 and 3.7 (published, one decimal) | ✓ |
| CII rating MARPOL Annex VI Reg. 28, MEPC.352–354(78) | Bulk carrier, 50,000 DWT, 3,000 t HFO, 50,000 nm, 2026 | attained 3.737, required 5.045: rating A | 3.737 and 5.045, A (by hand) | ✓ |
| EU ETS allowances Directive 2003/87/EC; Regulation 2015/757 Annex I | 3,000 t HFO between EU ports, 2026 | 9,489.3 allowances | 9,342 + 4.2 + 143.1 = 9,489.3 (by hand) | ✓ |
| FuelEU penalty Regulation (EU) 2023/1805 Annex IV | The same fuel, 2026 limit 89.34 g CO₂e/MJ | €186,309 | 292 t × 10⁶ ÷ (91.74 × 41,000) × 2,400 = €186,309 (by hand) | ✓ |
| EEXI requirement MARPOL Annex VI Reg. 24 Table 2 and Reg. 25 Table 3 | Bulk carrier, 93,000 DWT | required 3.28 g CO₂/t·nm | 0.80 × 961.79 × 93,000^−0.477 = 3.28 (by hand) | ✓ |
Each step of these is written out, with every parameter and its source, in the calculation guide.
2 · Against the verifier, ship type by ship type
The EU MRV register publishes, for each ship, the CO₂ its verifier counted for the EU ETS. We rebuild that figure from the register’s split by voyage type (100% between EU ports and at berth, 50% to or from the EU) and compare.
| Ship type | Ships | Same figure | Within 2% | More than 10% apart |
|---|---|---|---|---|
| Bulk carrier | 4,847 | 88% | 91% | 319 |
| General cargo ship | 3,020 | 60% | 71% | 699 |
| Container ship | 2,375 | 61% | 70% | 416 |
| Oil tanker | 2,007 | 76% | 86% | 130 |
| Chemical tanker | 1,636 | 61% | 76% | 197 |
| Vehicle carrier | 533 | 54% | 66% | 117 |
| Ro-pax ship | 426 | 45% | 56% | 155 |
| Gas carrier | 418 | 82% | 91% | 20 |
| LNG carrier | 408 | 88% | 93% | 16 |
| Ro-ro ship | 243 | 60% | 71% | 55 |
| Passenger ship (Cruise Passenger ship) | 207 | 26% | 43% | 51 |
| Refrigerated cargo carrier | 125 | 85% | 86% | 13 |
| Combination carrier | 5 | 40% | 80% | 0 |
3 · Where the differences come from
| Kind | Ships | Why |
|---|---|---|
| Exact (within half a tonne) | 11,537 | Our rebuild from the register's split by voyage type gives the verifier's figure. |
| Within 2% | 1,393 | Rounding and small scope differences. |
| Verifier reports no EU ETS emissions | 883 | The register shows EU voyages but the verifier reports zero for the EU ETS: an exclusion or exemption that the public data does not show. The bill uses the verifier's zero. |
| Our rebuild higher by more than 2% | 2,220 | Most likely derogations and special voyage rules the register does not itemise (outermost regions, small islands, public service obligations, ice class, neighbouring transhipment ports). The bill uses the verifier's figure. |
| Our rebuild lower by more than 2% | 217 | The verifier counts more than the 50% rule gives on the published split, for example voyages from a neighbouring transhipment port counted in full. The bill uses the verifier's figure. |
The bill uses the verifier's own EU ETS figure wherever the register gives one; our rebuild is shown as a cross-check and is used only for ships without a verifier figure. CarbonKeel is not an accredited verifier: allowances are surrendered on the figures the ship’s verifier accepts.
Contains data from EMSA THETIS-MRV, published under Article 21 of Regulation (EU) 2015/757. CarbonKeel’s figures are our own calculations from that data and are not endorsed by EMSA or the European Commission.