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 |
|---|---|---|---|---|---|
| 251 |
ANTIKITHIRA
IMO 9788980
|
14,999 | 2018 |
16.4
|
D |
| 252 |
ASTIPALEA
IMO 9711509
|
14,999 | 2015 |
16.5
|
D |
| 253 |
EPIC SARDINIA
IMO 9733571
|
9,000 | 2017 |
16.9
|
D |
| 254 |
GAZ SERENITY
IMO 9448499
|
17,022 | 2010 |
16.9
|
D |
| 255 |
GAZ FRATERNITY
IMO 9448487
|
17,022 | 2010 |
17.0
|
D |
| 256 |
BWEK BEAUTY
IMO 9974589
|
7,138 | 2023 |
17.0
|
D |
| 257 |
GAZ REDSEA
IMO 9264192
|
7,930 | 2002 |
17.0
|
D |
| 258 |
GAS WIDURI
IMO 9590668
|
17,400 | 2011 |
17.0
|
D |
| 259 |
DELTAGAS
IMO 9540003
|
14,999 | 2013 |
17.1
|
D |
| 260 |
PERTAMINA GAS AMARYLLIS
IMO 9895317
|
57,555 | 2021 |
17.1
|
D |
| 261 |
EPIC BREEZE
IMO 9892808
|
6,827 | 2020 |
17.2
|
D |
| 262 |
STINA KOSAN
IMO 9374569
|
10,348 | 2008 |
17.3
|
D |
| 263 |
EPIC BONAIRE
IMO 9743253
|
7,198 | 2014 |
17.6
|
D |
| 264 |
TAUGAS
IMO 9675080
|
14,999 | 2015 |
17.7
|
D |
| 265 |
GAZ VICTORY
IMO 9458171
|
17,672 | 2010 |
17.8
|
D |
| 266 |
EPIC MANHATTAN
IMO 9392236
|
9,127 | 2007 |
17.9
|
D |
| 267 |
MYGAS
IMO 9694397
|
14,999 | 2017 |
18.0
|
D |
| 268 |
RHOURD EL HAMRA
IMO 9337793
|
19,277 | 2008 |
18.1
|
D |
| 269 |
BWEK MAURITIUS
IMO 9392250
|
9,127 | 2005 |
18.9
|
D |
| 270 |
GAS LISBON
IMO 9267974
|
8,064 | 2002 |
18.9
|
D |
| 271 |
PGC STRIDENT FORCE
IMO 9205574
|
8,485 | 1999 |
19.0
|
D |
| 272 |
NORTHERN PATHFINDER
IMO 9954230
|
10,188 | 2024 |
19.4
|
D |
| 273 |
GAS TRUST
IMO 9522269
|
10,338 | 2010 |
19.4
|
D |
| 274 |
EPIC BORINQUEN
IMO 9743241
|
7,183 | 2016 |
19.5
|
D |
| 275 |
GAS WALIO
IMO 9590670
|
17,400 | 2011 |
19.6
|
D |
| 276 |
KILBURN
IMO 9664938
|
8,586 | 2013 |
20.1
|
D |
| 277 |
BWEK ARUBA
IMO 9383338
|
10,308 | 2006 |
20.1
|
E |
| 278 |
GASCHEM RHONE
IMO 9401570
|
7,341 | 2008 |
20.1
|
E |
| 279 |
CHEIKH BOUAMAMA
IMO 9324344
|
39,483 | 2008 |
20.1
|
E |
| 280 |
GASCHEM ALSTER
IMO 9961714
|
6,570 | 2024 |
20.2
|
E |
| 281 |
GAS HARALAMBOS
IMO 9423126
|
7,331 | 2007 |
20.6
|
E |
| 282 |
EPIC BORACAY
IMO 9521588
|
6,519 | 2007 |
20.9
|
E |
| 283 |
PGC EIRINI
IMO 9800178
|
6,602 | 2018 |
21.0
|
E |
| 284 |
GAZ VENTURE
IMO 9506162
|
10,266 | 2011 |
21.0
|
E |
| 285 |
EPIC BALI
IMO 9519523
|
6,022 | 2010 |
21.2
|
E |
| 286 |
GAZ HORIZON
IMO 9572563
|
6,519 | 2011 |
21.2
|
E |
| 287 |
BWEK TAHITI
IMO 9506186
|
7,879 | 2010 |
21.6
|
E |
| 288 |
GASCHEM SHINANO
IMO 9269271
|
7,413 | 2007 |
21.7
|
E |
| 289 |
MORITZ SCHULTE
IMO 9220794
|
9,174 | 2002 |
21.8
|
E |
| 290 |
NORTHERN PIONEER
IMO 9954228
|
10,170 | 2024 |
21.8
|
E |
| 291 |
KIRKBY
IMO 9652753
|
8,576 | 2013 |
21.9
|
E |
| 292 |
GAZ DYNAMIC
IMO 9612844
|
6,044 | 2011 |
22.0
|
E |
| 293 |
BEYKOZ
IMO 9558945
|
8,677 | 2009 |
22.0
|
E |
| 294 |
GAZ EXPLORER
IMO 9506150
|
10,266 | 2010 |
22.1
|
E |
| 295 |
GAZ UNITED
IMO 9511650
|
10,314 | 2011 |
22.1
|
E |
| 296 |
GAS ESCO
IMO 9507752
|
7,207 | 2012 |
22.2
|
E |
| 297 |
GREMIO
IMO 9699256
|
6,486 | 2014 |
22.5
|
E |
| 298 |
ALEXANDRA KOSAN
IMO 9342413
|
8,586 | 2008 |
22.5
|
E |
| 299 |
SYN ACRAB
IMO 9251781
|
9,328 | 2003 |
22.6
|
E |
| 300 |
PGC ARATOS
IMO 9251779
|
9,329 | 2003 |
22.6
|
E |
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.