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 |
|---|---|---|---|---|---|
| 102 |
CERRO ALTO EXPLORER
IMO 9940435
|
29,229 | 2023 |
7.9
|
B |
| 101 |
TESSALA
IMO 9761243
|
94,575 | 2016 |
7.9
|
B |
| 103 |
HELLAS GLADIATOR
IMO 9732503
|
54,376 | 2016 |
7.9
|
B |
| 104 |
MARCELLA
IMO 9934668
|
30,070 | 2023 |
7.9
|
B |
| 105 |
DORSET
IMO 9470088
|
53,076 | 2011 |
8.0
|
B |
| 106 |
GASCHEM AFRICA
IMO 9961219
|
29,230 | 2024 |
8.0
|
B |
| 107 |
GASCHEM ERICA
IMO 9961207
|
29,193 | 2024 |
8.0
|
B |
| 108 |
PASCO BERKE
IMO 9978028
|
29,175 | 2024 |
8.1
|
B |
| 109 |
BW MONSOON
IMO 9667564
|
53,752 | 2015 |
8.1
|
B |
| 110 |
GAS QUILA
IMO 9710385
|
53,765 | 2016 |
8.1
|
B |
| 111 |
CLIPPER MARS
IMO 9377078
|
43,544 | 2008 |
8.1
|
B |
| 112 |
CLIPPER JUPITER
IMO 9699505
|
42,543 | 2015 |
8.1
|
B |
| 113 |
LA CONDAMINE
IMO 9941324
|
29,381 | 2023 |
8.2
|
B |
| 115 |
PINZA
IMO 9790232
|
51,202 | 2018 |
8.3
|
B |
| 114 |
KAUPANG
IMO 9914620
|
29,649 | 2022 |
8.3
|
B |
| 116 |
ALRAR
IMO 9284013
|
44,451 | 2004 |
8.4
|
B |
| 117 |
MYKLEBUST
IMO 9914632
|
29,649 | 2022 |
8.4
|
B |
| 118 |
ECO ENCHANTED
IMO 9945796
|
30,062 | 2024 |
8.4
|
B |
| 119 |
SIFNOS LADY
IMO 9903073
|
28,379 | 2021 |
8.4
|
B |
| 120 |
NAVIGATOR CAPRICORN
IMO 9403774
|
23,328 | 2008 |
8.4
|
B |
| 121 |
YUKON
IMO 9852145
|
28,627 | 2020 |
8.5
|
B |
| 122 |
YARA FREYA
IMO 9725500
|
28,735 | 2016 |
8.5
|
B |
| 123 |
PERMIAN LADY
IMO 9729269
|
28,372 | 2016 |
8.5
|
B |
| 124 |
YARA AESA
IMO 9725495
|
28,735 | 2016 |
8.6
|
B |
| 125 |
GUADALUPE EXPLORER
IMO 9926934
|
29,421 | 2022 |
8.7
|
B |
| 126 |
ECO SORCERER
IMO 9933468
|
30,062 | 2023 |
8.7
|
B |
| 127 |
ECO MERLIN
IMO 9929194
|
30,062 | 2023 |
8.7
|
B |
| 128 |
BRILLIANT FUTURE
IMO 9987615
|
25,009 | 2024 |
8.7
|
B |
| 129 |
STIKLESTAD
IMO 9914644
|
29,649 | 2022 |
8.7
|
B |
| 130 |
NAVIGATOR YAUZA
IMO 9761176
|
22,800 | 2017 |
8.8
|
B |
| 131 |
GASCHEM EUROPE
IMO 9961192
|
29,181 | 2023 |
8.8
|
B |
| 132 |
NAVIGATOR PHOENIX
IMO 9407330
|
23,640 | 2009 |
8.8
|
B |
| 133 |
NOVA BREEZE
IMO 9543081
|
28,202 | 2017 |
8.9
|
B |
| 134 |
ENRICO FERMI
IMO 9789312
|
28,532 | 2018 |
8.9
|
B |
| 135 |
BAKKEN LADY
IMO 9711834
|
28,372 | 2015 |
8.9
|
B |
| 136 |
SEASHINE
IMO 9787352
|
28,467 | 2018 |
9.0
|
B |
| 137 |
MANITOBA
IMO 9738234
|
28,543 | 2016 |
9.0
|
B |
| 138 |
EAGLE FORD LADY
IMO 9711846
|
28,372 | 2016 |
9.0
|
B |
| 139 |
SOMBEKE
IMO 9292113
|
29,213 | 2006 |
9.1
|
C |
| 140 |
ECO ARCTIC
IMO 9746683
|
26,798 | 2018 |
9.1
|
C |
| 141 |
ECO WIZARD
IMO 9941568
|
30,062 | 2024 |
9.1
|
C |
| 142 |
NAVIGATOR SCORPIO
IMO 9404792
|
23,333 | 2009 |
9.2
|
C |
| 143 |
HOURAI MARU
IMO 9796585
|
28,894 | 2019 |
9.3
|
C |
| 145 |
SAHARA GAS
IMO 9748215
|
28,637 | 2017 |
9.3
|
C |
| 144 |
GAS UTOPIA
IMO 9770531
|
28,672 | 2017 |
9.3
|
C |
| 146 |
NORDICO
IMO 9336658
|
29,565 | 2007 |
9.3
|
C |
| 147 |
ECO FREEZE
IMO 9755658
|
26,417 | 2018 |
9.4
|
C |
| 149 |
KAPRIJKE
IMO 9687485
|
29,639 | 2015 |
9.4
|
C |
| 148 |
OCEANIC STAR
IMO 9447794
|
26,416 | 2009 |
9.4
|
C |
| 150 |
BERING GAS
IMO 9745536
|
24,244 | 2016 |
9.4
|
C |
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.