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 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 |
|---|---|---|---|---|---|
| 51 |
BW CARINA
IMO 9701798
|
54,561 | 2015 |
6.6
|
A |
| 52 |
GAS BARBAROSSA
IMO 9903762
|
53,759 | 2021 |
6.6
|
A |
| 53 |
VIVIT FORNAX
IMO 9835185
|
54,406 | 2019 |
6.7
|
A |
| 54 |
SAKURA GAS
IMO 9629873
|
55,214 | 2013 |
6.7
|
A |
| 56 |
GLOBE ATLAS
IMO 9765550
|
54,994 | 2016 |
6.7
|
A |
| 55 |
HELLAS DYNASTY
IMO 9869241
|
51,116 | 2020 |
6.7
|
A |
| 57 |
KEDARNATH
IMO 9699995
|
54,557 | 2016 |
6.8
|
A |
| 58 |
HALLASAN EXPLORER
IMO 9941219
|
54,994 | 2023 |
6.8
|
A |
| 59 |
NS DREAM
IMO 9800506
|
54,052 | 2019 |
6.8
|
A |
| 60 |
VIVIT ALTAIS
IMO 9840879
|
50,703 | 2019 |
6.8
|
A |
| 61 |
HELSINKI
IMO 9377224
|
43,601 | 2009 |
6.8
|
A |
| 62 |
LILAC PROMENADE
IMO 9809540
|
53,938 | 2019 |
6.9
|
A |
| 63 |
WHITE CLIFFS
IMO 9902172
|
53,971 | 2021 |
6.9
|
A |
| 64 |
SANSOVINO
IMO 9734525
|
54,481 | 2016 |
7.0
|
A |
| 66 |
CRYSTAL ANGEL
IMO 9833199
|
53,995 | 2020 |
7.0
|
A |
| 65 |
JEAN RASPAIL
IMO 9904091
|
57,847 | 2022 |
7.0
|
A |
| 67 |
FLANDERS PIONEER
IMO 9897559
|
54,857 | 2021 |
7.0
|
A |
| 68 |
HELLAS POSEIDON
IMO 9721140
|
54,361 | 2015 |
7.1
|
A |
| 69 |
MUSANAH
IMO 9415648
|
54,804 | 2009 |
7.1
|
A |
| 71 |
RED ADMIRAL
IMO 9903140
|
53,914 | 2021 |
7.2
|
B |
| 70 |
AQUAMARINE PROGRESS
IMO 9415650
|
54,866 | 2010 |
7.2
|
B |
| 72 |
REGGANE
IMO 9176357
|
54,592 | 1999 |
7.2
|
B |
| 73 |
GAS KAISERIN
IMO 9941001
|
55,141 | 2023 |
7.2
|
B |
| 74 |
COMET
IMO 9689914
|
54,420 | 2014 |
7.2
|
B |
| 76 |
ORIENTAL JUBILEE
IMO 9763813
|
54,520 | 2016 |
7.2
|
B |
| 75 |
HELLAS VOYAGER
IMO 9869253
|
51,116 | 2020 |
7.2
|
B |
| 77 |
MIRAI
IMO 9929871
|
35,941 | 2023 |
7.3
|
B |
| 79 |
OUGARTA
IMO 9761267
|
94,575 | 2017 |
7.3
|
B |
| 78 |
JIRISAN EXPLORER
IMO 9941221
|
54,994 | 2023 |
7.3
|
B |
| 80 |
GAS STELLA
IMO 9765562
|
55,001 | 2017 |
7.3
|
B |
| 81 |
DENVER
IMO 9377236
|
43,563 | 2009 |
7.3
|
B |
| 82 |
CLIPPER QUITO
IMO 9630755
|
55,047 | 2013 |
7.3
|
B |
| 83 |
YUHSAN
IMO 9238272
|
49,999 | 2002 |
7.4
|
B |
| 84 |
CLIPPER SKY
IMO 9277943
|
44,617 | 2004 |
7.4
|
B |
| 85 |
ECO ORACLE
IMO 9936549
|
30,062 | 2024 |
7.5
|
B |
| 86 |
INDIANAPOLIS
IMO 9925679
|
30,128 | 2023 |
7.5
|
B |
| 87 |
CHRYSOPIGI LADY
IMO 9936537
|
29,703 | 2023 |
7.5
|
B |
| 88 |
GAS ANAX
IMO 9934486
|
30,138 | 2023 |
7.6
|
B |
| 89 |
GREEN POWER
IMO 9927316
|
30,108 | 2023 |
7.6
|
B |
| 90 |
TETHYS
IMO 9625152
|
54,901 | 2013 |
7.7
|
B |
| 91 |
GREEN ENDEAVOUR
IMO 1018470
|
32,729 | 2025 |
7.7
|
B |
| 93 |
KALLO
IMO 9719276
|
29,664 | 2017 |
7.7
|
B |
| 92 |
CHAMPAGNY
IMO 9983499
|
33,623 | 2025 |
7.7
|
B |
| 94 |
NYMFAION LADY
IMO 9926752
|
29,703 | 2023 |
7.8
|
B |
| 95 |
GREEN ENERGY
IMO 9925667
|
30,093 | 2022 |
7.8
|
B |
| 96 |
SUNNY VISTA
IMO 9607758
|
54,929 | 2013 |
7.8
|
B |
| 98 |
CHEYENNE
IMO 9706504
|
54,555 | 2015 |
7.8
|
B |
| 97 |
RHOURD ENOUSS
IMO 9284025
|
44,399 | 2004 |
7.8
|
B |
| 100 |
ASTOR
IMO 9934670
|
30,112 | 2023 |
7.8
|
B |
| 99 |
BORDA
IMO 9772826
|
44,452 | 2016 |
7.8
|
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.