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 |
|---|---|---|---|---|---|
| 151 |
MANTA MALAZGIRT
IMO 9926946
|
29,386 | 2023 |
9.5
|
C |
| 152 |
AFRICA GAS
IMO 9744128
|
28,637 | 2017 |
9.5
|
C |
| 153 |
NAVIGATOR CASTOR
IMO 9714642
|
23,708 | 2019 |
9.5
|
C |
| 154 |
GAS VENUS
IMO 9774197
|
28,702 | 2017 |
9.5
|
C |
| 155 |
ONTARIO
IMO 9744831
|
28,543 | 2017 |
9.5
|
C |
| 156 |
WAASMUNSTER
IMO 9659103
|
28,518 | 2014 |
9.6
|
C |
| 157 |
MARCELLUS LADY
IMO 9722780
|
28,372 | 2016 |
9.6
|
C |
| 158 |
WINNIPEG
IMO 9852133
|
28,627 | 2019 |
9.6
|
C |
| 159 |
WARISOULX
IMO 9659139
|
28,590 | 2015 |
9.8
|
C |
| 160 |
ECO ICE
IMO 9755646
|
26,798 | 2018 |
9.8
|
C |
| 161 |
NAVIGATOR CELTIC
IMO 9682265
|
24,281 | 2015 |
9.8
|
C |
| 162 |
SEASURFER
IMO 9763033
|
28,447 | 2017 |
9.8
|
C |
| 163 |
NAVIGATOR EQUATOR
IMO 9714654
|
23,724 | 2019 |
9.9
|
C |
| 164 |
NAVIGATOR VEGA
IMO 9714630
|
23,704 | 2019 |
9.9
|
C |
| 165 |
KAPELLEN
IMO 9719290
|
29,590 | 2018 |
10.0
|
C |
| 166 |
SEARAMBLER
IMO 9892822
|
28,077 | 2021 |
10.0
|
C |
| 167 |
KONTICH
IMO 9687502
|
29,461 | 2016 |
10.1
|
C |
| 168 |
ECO FROST
IMO 9746671
|
26,798 | 2017 |
10.2
|
C |
| 169 |
NAVIGATOR ATLANTIC
IMO 9662019
|
24,231 | 2014 |
10.2
|
C |
| 170 |
ARRHENIUS
IMO 9471032
|
26,645 | 2010 |
10.2
|
C |
| 171 |
MANTA DICLE
IMO 9666675
|
28,210 | 2013 |
10.2
|
C |
| 172 |
SEVERIN SCHULTE
IMO 9659115
|
28,521 | 2014 |
10.3
|
C |
| 173 |
LALLA FATMA N'SOUMER
IMO 9275347
|
80,920 | 2004 |
10.3
|
C |
| 174 |
THEKLA SCHULTE
IMO 9551777
|
14,999 | 2014 |
10.3
|
C |
| 175 |
KOKSIJDE
IMO 9719305
|
29,543 | 2018 |
10.4
|
C |
| 176 |
CHESHIRE
IMO 9369772
|
26,471 | 2008 |
10.4
|
C |
| 177 |
BERTOLLE
IMO 9177545
|
23,495 | 2000 |
10.5
|
C |
| 178 |
NAVIGATOR PEGASUS
IMO 9407328
|
24,640 | 2009 |
10.5
|
C |
| 179 |
SAPET GAS
IMO 9922213
|
17,872 | 2022 |
10.6
|
C |
| 180 |
NAVIGATOR TITAN
IMO 9402598
|
18,959 | 2010 |
10.8
|
C |
| 181 |
PASCO SYLVIE
IMO 9332066
|
26,348 | 2007 |
10.9
|
C |
| 182 |
NAVIGATOR AURORA
IMO 9726322
|
27,037 | 2016 |
11.1
|
C |
| 183 |
GASCHEM DOLLART
IMO 9744776
|
23,663 | 2020 |
11.1
|
C |
| 184 |
KNOKKE
IMO 9687497
|
29,478 | 2016 |
11.1
|
C |
| 185 |
ALCOR
IMO 9655511
|
22,765 | 2013 |
11.1
|
C |
| 186 |
OCEANIC MOON
IMO 9447809
|
26,416 | 2011 |
11.2
|
C |
| 187 |
QUEBEC
IMO 9744843
|
28,543 | 2017 |
11.3
|
C |
| 188 |
MANTA ANKA
IMO 9666663
|
28,263 | 2013 |
11.3
|
C |
| 189 |
THERESA SCHULTE
IMO 9553622
|
14,999 | 2014 |
11.3
|
C |
| 190 |
INEOS INVENTION
IMO 9771511
|
20,738 | 2017 |
11.4
|
C |
| 191 |
DANCING BRAVE
IMO 9798179
|
16,600 | 2018 |
11.4
|
C |
| 192 |
GAS NORDSEE
IMO 9402562
|
18,846 | 2009 |
11.4
|
C |
| 193 |
CLIPPER EIRENE
IMO 9834715
|
18,063 | 2019 |
11.5
|
C |
| 194 |
INEOS INNOVATION
IMO 9744958
|
20,917 | 2016 |
11.6
|
C |
| 195 |
OCEANIC BREEZE
IMO 9451991
|
26,416 | 2011 |
11.7
|
C |
| 196 |
NAVIGATOR LUNA
IMO 9712553
|
18,599 | 2018 |
11.8
|
C |
| 197 |
INEOS INTREPID
IMO 9685449
|
20,917 | 2015 |
12.1
|
C |
| 198 |
INEOS INSIGHT
IMO 9685425
|
20,918 | 2015 |
12.1
|
C |
| 199 |
INEOS INDEPENDENCE
IMO 9744960
|
20,918 | 2017 |
12.1
|
C |
| 200 |
YARA SELA
IMO 9734850
|
18,547 | 2016 |
12.3
|
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.