The IMO Net-Zero Framework, approved at MEPC 83 in April 2025, requires every ship of 5,000 GT and above engaged on international voyages to achieve an Attained GHG Fuel Intensity (GFI) at or below an annually-tightening Required GFI from 1 January 2027. Ships exceeding the Required GFI must surrender Remediation Units (RUs) at a price set by the IMO; ships at or below the Direct Compliance Threshold (DCT) earn Surplus Units (SUs) that may be banked for up to five years or traded.
Required GFI and DCT
$$ \text{GFI}\text{required}(y) = \text{GFI}\text{2008} \cdot \left(1 - r(y)\right) $$
$$ \text{GFI}\text{DCT}(y) = \text{GFI}\text{2008} \cdot \left(1 - d(y)\right) $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\text{GFI}_\text{required}(y)$ | Required GFI for year $y$ | g CO₂e / MJ | MEPC 83 Annex |
| $\text{GFI}_\text{DCT}(y)$ | Direct Compliance Threshold for year $y$ | g CO₂e / MJ | MEPC 83 Annex |
| $\text{GFI}_\text{2008}$ | Well-to-wake baseline of the 2008 international shipping fuel mix | g CO₂e / MJ | 92.0, MEPC.391(82) |
| $r(y)$ | Required GFI reduction fraction for year $y$ | fraction | MEPC 83 trajectory |
| $d(y)$ | DCT reduction fraction for year $y$ | fraction | MEPC 83 trajectory |
RU obligation
$$ \text{RU obligation (tCO}_2\text{e)} = \max\left(\text{GFI}a - \text{GFI}\text{required},\ 0\right) \cdot E \cdot 10^{-6} $$
SU credit
$$ \text{SU credit (tCO}2\text{e)} = \max\left(\text{GFI}\text{DCT} - \text{GFI}_a,\ 0\right) \cdot E \cdot 10^{-6} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\text{GFI}_a$ | Attained GFI for the reporting year | g CO₂e / MJ | result of GFI Attained |
| $E$ | Total annual energy used (sum of mass × LHV across all fuels) | MJ | IMO DCS report |
| $10^{-6}$ | Unit conversion (g → t) | - | constant |
USD cost
$$ \text{Cost (USD)} = \text{RU obligation} \cdot P_\text{RU} $$
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $P_\text{RU}$ | Remediation Unit price set by the IMO | USD / t CO₂e | MEPC 83 trajectory |
Reduction trajectory (relative to 2008 baseline of 92.0 g CO₂e/MJ)
| Year | Required GFI reduction | Required GFI | DCT reduction | DCT |
|---|---|---|---|---|
| 2027 | 1.5% | 90.6 | 17% | 76.4 |
| 2028 | 4.0% | 88.3 | 21% | 72.7 |
| 2029 | 8.0% | 84.6 | 26% | 68.1 |
| 2030 | 17.0% | 76.4 | 32% | 62.6 |
| 2031 | 21.0% | 72.7 | 34% | 60.7 |
| 2032 | 24.0% | 69.9 | 36% | 58.9 |
| 2033 | 27.0% | 67.2 | 39% | 56.1 |
| 2034 | 28.5% | 65.8 | 41% | 54.3 |
| 2035 | 30.0% | 64.4 | 43% | 52.4 |
| 2040 | 65.0% | 32.2 | 79% | 19.3 |
Values for years not on the published table are linearly interpolated. The trajectory was approved at MEPC 83 in April 2025 and is subject to formal adoption at MEPC 84 in October 2025; the post-2040 trajectory will be finalised at MEPC 92 in 2031.
RU price trajectory
| Year | RU price (USD / t CO₂e) |
|---|---|
| 2027 | 100 |
| 2030 | 150 |
| 2035 | 250 |
| 2040 | 400 |
The price is reviewed every five years by MEPC. Override the default in the live calculator to test sensitivity.
Sources
- IMO MEPC 83 (April 2025) - Net-Zero Framework approval document.
- IMO Resolution MEPC.377(80) - 2023 Revised IMO Strategy on Reduction of GHG Emissions from Ships.
- IMO MEPC.376(80) - 2024 Guidelines on Lifecycle GHG Intensity of Marine Fuels.
- IMO MEPC.391(82) - 2024 Update to LCA Guidelines (default pathway values).
See also
- GFI Attained calculator - companion calculator computing the input attained GFI.
- Wiki: IMO Net-Zero Framework.
- Wiki: IMO GHG Strategy.
- Wiki: MARPOL Annex VI.