Most Emission-Efficient Oil Tankers
Ships ranked by AER (Annual Efficiency Ratio) — grams of CO₂ emitted per tonne of deadweight carried one nautical mile (g CO₂/dwt·nm), the IMO carbon-intensity metric behind the CII rating — from official EU MRV emissions data for reporting year 2025. Lower is greener. Pick a segment and size class to see the greenest vessels first.
| # | Vessel | Size (DWT) | Built | Carbon intensity — AER (g CO₂/dwt·nm) | Grade |
|---|---|---|---|---|---|
| 399 |
NAUTILUS I
IMO 9298765
|
163,927 | 2006 |
3.1
|
B |
| 405 |
GEM
IMO 9406001
|
156,840 | 2010 |
3.1
|
B |
| 404 |
FRONT IDUN
IMO 9600944
|
157,000 | 2015 |
3.1
|
B |
| 403 |
KEDROS
IMO 1016214
|
113,920 | 2025 |
3.1
|
B |
| 402 |
THOMAS ZAFIRAS
IMO 9724087
|
113,691 | 2016 |
3.1
|
B |
| 410 |
DILIGENT WARRIOR
IMO 9750050
|
159,000 | 2016 |
3.1
|
B |
| 409 |
AISOPOS
IMO 9987029
|
115,621 | 2025 |
3.1
|
B |
| 411 |
BREEZE
IMO 9809356
|
156,682 | 2018 |
3.1
|
B |
| 408 |
ORIENT M
IMO 9907225
|
156,729 | 2022 |
3.1
|
B |
| 407 |
AEGEAN HORIZON
IMO 9326811
|
158,738 | 2007 |
3.1
|
B |
| 406 |
NICOLAOS
IMO 9429297
|
164,758 | 2010 |
3.1
|
B |
| 414 |
MARLIN LA PLATA
IMO 9823560
|
114,752 | 2022 |
3.1
|
B |
| 413 |
MARE PICENUM
IMO 9449405
|
158,489 | 2011 |
3.1
|
B |
| 416 |
HAFNIA LARVIK
IMO 9946465
|
109,999 | 2023 |
3.1
|
B |
| 412 |
AQUAHONOR
IMO 9925136
|
157,746 | 2022 |
3.1
|
B |
| 417 |
STENA SURPRISE
IMO 9533995
|
158,491 | 2012 |
3.1
|
B |
| 415 |
POLIEGOS
IMO 9746621
|
157,540 | 2017 |
3.1
|
B |
| 418 |
DF MYSTRAS
IMO 9941702
|
109,999 | 2023 |
3.1
|
B |
| 421 |
P. TOKYO
IMO 1057206
|
114,014 | 2025 |
3.1
|
B |
| 420 |
COPPER SPIRIT
IMO 9427639
|
156,827 | 2010 |
3.1
|
B |
| 419 |
TAHITI
IMO 9600877
|
157,022 | 2014 |
3.1
|
B |
| 422 |
CHRISTINA
IMO 9772125
|
158,902 | 2016 |
3.1
|
B |
| 424 |
TORM HELLERUP
IMO 9798002
|
114,951 | 2018 |
3.1
|
B |
| 423 |
SEAWAYS SAN SABA
IMO 9593426
|
159,018 | 2012 |
3.1
|
B |
| 429 |
KASTOS
IMO 1016226
|
113,897 | 2025 |
3.1
|
B |
| 428 |
NAVIG8 PRIDE LHJ
IMO 9947366
|
109,999 | 2023 |
3.1
|
B |
| 427 |
KUFRA
IMO 9935155
|
115,519 | 2023 |
3.1
|
B |
| 426 |
AFRICA
IMO 9905320
|
163,220 | 2022 |
3.1
|
B |
| 425 |
DF MONTMARTE
IMO 9941714
|
109,999 | 2023 |
3.1
|
B |
| 430 |
AQUAFREEDOM
IMO 9922823
|
157,746 | 2022 |
3.1
|
B |
| 433 |
COBALT SUN
IMO 9814428
|
114,395 | 2015 |
3.1
|
B |
| 435 |
P. MASSPORT
IMO 9997476
|
114,036 | 2025 |
3.1
|
B |
| 432 |
NANTUCKET
IMO 9600865
|
157,000 | 2014 |
3.1
|
B |
| 431 |
STRYMON
IMO 9938030
|
115,429 | 2022 |
3.1
|
B |
| 434 |
NORDIC MOON
IMO 9742900
|
154,781 | 2016 |
3.1
|
B |
| 436 |
SUMMIT SPIRIT
IMO 9404833
|
159,955 | 2008 |
3.1
|
B |
| 438 |
MINERVA ASTRA
IMO 9893008
|
115,484 | 2021 |
3.1
|
B |
| 440 |
MINERVA GEORGIA
IMO 9332157
|
163,417 | 2008 |
3.1
|
B |
| 439 |
OSLO STAR
IMO 9984883
|
115,332 | 2022 |
3.1
|
B |
| 437 |
TP SPIRIT
IMO 9645413
|
114,139 | 2016 |
3.1
|
B |
| 449 |
MARLIN LORETO
IMO 9823558
|
114,823 | 2021 |
3.1
|
B |
| 448 |
OTTOMAN SINCERITY
IMO 9788710
|
152,516 | 2017 |
3.1
|
B |
| 442 |
RED MOON
IMO 9590307
|
160,024 | 2012 |
3.1
|
B |
| 447 |
MILITOS
IMO 9607435
|
164,751 | 2012 |
3.1
|
B |
| 446 |
MINERVA CORALIA
IMO 9728239
|
113,850 | 2017 |
3.1
|
B |
| 445 |
BURRI
IMO 9787948
|
115,018 | 2015 |
3.1
|
B |
| 444 |
SAQR
IMO 9956018
|
113,385 | 2021 |
3.1
|
B |
| 443 |
MAUI
IMO 1040722
|
115,173 | 2025 |
3.1
|
B |
| 441 |
ITHAKI WARRIOR
IMO 9765366
|
159,962 | 2017 |
3.1
|
B |
| 450 |
PENELOPE
IMO 9941726
|
114,763 | 2023 |
3.1
|
B |
Which engines power the greenest fleets?
The main engine is the single largest CO₂ source on board — typically well over 80% of a ship's emissions come from propulsion. We aggregated this ranking the other way around: every engine design is scored by the measured carbon intensity of the vessels carrying it, licensee-built units merged under their design brand. The verdict from the 2025 data — modern dual-fuel designs like MAN B&W's ME-GI and WinGD's X-DF families, together with EGR/SCR-abated and ultra-long-stroke G-type engines, consistently power the most emission-friendly ships in service.
AER (Annual Efficiency Ratio) = annual CO₂ emissions ÷ (deadweight × distance sailed), the IMO carbon-intensity metric used for CII ratings. It is built only from measured CO₂, distance and deadweight — not the self-reported cargo transport-work figure, which is unreliable. Implausible outliers (top 2% per segment) are excluded. Grade A–E reflects each vessel's rank within its segment. Source: EMSA THETIS-MRV.