Most Emission-Efficient Gas Carriers
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 2024. 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 |
|---|---|---|---|---|---|
| 1 |
ARCTIC GAS
IMO 9745512
|
24,303 | 2017 |
4.5
|
A |
| 2 |
ASTERIX I
IMO 9892298
|
93,403 | 2023 |
4.7
|
A |
| 3 |
ARISTIDIS I
IMO 9862906
|
93,368 | 2021 |
5.3
|
A |
| 4 |
HANNIBAL
IMO 9933523
|
58,000 | 2024 |
5.3
|
A |
| 5 |
COMET
IMO 9689914
|
54,420 | 2014 |
5.3
|
A |
| 6 |
NILE RIVER
IMO 9933779
|
58,666 | 2024 |
5.4
|
A |
| 7 |
ARISTARCHOS
IMO 9862918
|
93,427 | 2021 |
5.4
|
A |
| 8 |
ASKLIPIOS
IMO 9884021
|
93,352 | 2021 |
5.4
|
A |
| 9 |
OCEANUS AURORA
IMO 9555008
|
58,495 | 2023 |
5.5
|
A |
| 10 |
ADAMASTOS
IMO 9879698
|
93,566 | 2021 |
5.5
|
A |
| 11 |
AXIOS II
IMO 9943853
|
93,736 | 2021 |
5.5
|
A |
| 12 |
KAEDE
IMO 9932581
|
59,320 | 2023 |
5.6
|
A |
| 13 |
TESSALA
IMO 9761243
|
94,575 | 2016 |
5.8
|
A |
| 14 |
LEGISLATOR
IMO 9938523
|
59,017 | 2022 |
5.9
|
A |
| 15 |
CRYSTAL RIVER
IMO 9780641
|
54,171 | 2017 |
5.9
|
A |
| 16 |
PHOENIX HARMONIA
IMO 9947483
|
56,711 | 2023 |
5.9
|
A |
| 17 |
MERCATOR
IMO 9938535
|
59,017 | 2023 |
6.0
|
A |
| 18 |
CONSTELLATION
IMO 9734680
|
54,335 | 2014 |
6.0
|
A |
| 20 |
LANTANA PLANET
IMO 9933444
|
55,153 | 2023 |
6.1
|
A |
| 19 |
ENEOS WISDOM
IMO 9935507
|
59,504 | 2022 |
6.1
|
A |
| 21 |
ATTALOS
IMO 9862920
|
93,321 | 2021 |
6.1
|
A |
| 22 |
SUMIRE GAS
IMO 9723681
|
54,243 | 2016 |
6.2
|
A |
| 23 |
CHEYENNE
IMO 9706504
|
54,555 | 2015 |
6.2
|
A |
| 24 |
PERTAMINA GAS DAHLIA
IMO 9937074
|
58,265 | 2024 |
6.2
|
A |
| 25 |
BW TUCANA
IMO 9735658
|
54,116 | 2016 |
6.2
|
A |
| 26 |
PINZA
IMO 9790232
|
51,202 | 2018 |
6.2
|
A |
| 27 |
AEOLIAN PEARL
IMO 9754824
|
54,675 | 2016 |
6.2
|
A |
| 28 |
BW VAR
IMO 9748227
|
54,053 | 2016 |
6.3
|
A |
| 29 |
PERTAMINA GAS CASPIA
IMO 9937062
|
58,257 | 2024 |
6.3
|
A |
| 31 |
GAS STELLA
IMO 9765562
|
55,001 | 2017 |
6.4
|
A |
| 30 |
CLIPPER WILMA
IMO 9855941
|
51,098 | 2019 |
6.4
|
A |
| 32 |
GAS NOUVEAU BAUHINIA
IMO 9958987
|
58,201 | 2024 |
6.4
|
A |
| 33 |
GAS BARBAROSSA
IMO 9903762
|
53,759 | 2021 |
6.4
|
A |
| 34 |
BW MESSINA
IMO 9735062
|
54,647 | 2017 |
6.5
|
A |
| 35 |
MANIFESTO
IMO 9625152
|
54,901 | 2013 |
6.5
|
A |
| 36 |
ARISTOS I
IMO 9862891
|
93,448 | 2020 |
6.5
|
A |
| 37 |
DURHAM
IMO 9889564
|
55,408 | 2021 |
6.6
|
A |
| 38 |
BW TOKYO
IMO 9398307
|
54,936 | 2009 |
6.6
|
A |
| 39 |
VIVIT FORNAX
IMO 9835185
|
54,406 | 2019 |
6.7
|
A |
| 40 |
SHAHRASTANI
IMO 9726085
|
54,702 | 2016 |
6.7
|
A |
| 41 |
GAZ IMPERIAL
IMO 9795919
|
54,304 | 2018 |
6.7
|
A |
| 42 |
NS DREAM
IMO 9800506
|
54,052 | 2019 |
6.8
|
A |
| 43 |
VIVIT THUBAN
IMO 9840867
|
50,703 | 2019 |
6.8
|
A |
| 44 |
HAMPSHIRE
IMO 9377781
|
53,293 | 2007 |
6.8
|
A |
| 45 |
PYXIS PIONEER
IMO 9792747
|
53,928 | 2019 |
6.8
|
A |
| 46 |
HELLAS POSEIDON
IMO 9721140
|
54,361 | 2015 |
6.8
|
A |
| 47 |
SARV SHAKTI
IMO 9350599
|
54,783 | 2008 |
6.8
|
A |
| 48 |
OUGARTA
IMO 9761267
|
94,575 | 2017 |
6.9
|
A |
| 50 |
CONCORDE
IMO 9734678
|
53,999 | 2015 |
6.9
|
A |
| 49 |
AXIS RIVER
IMO 9949704
|
56,503 | 2023 |
6.9
|
A |
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 2024 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.