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 |
|---|---|---|---|---|---|
| 301 |
GAZ CONCORD
IMO 9506174
|
10,313 | 2011 |
22.7
|
E |
| 302 |
PGC TAORMINA
IMO 9800166
|
6,612 | 2017 |
22.7
|
E |
| 303 |
EPIC SHIKOKU
IMO 9733545
|
8,993 | 2016 |
23.0
|
E |
| 304 |
ECO GALAXY
IMO 9715555
|
5,873 | 2015 |
23.1
|
E |
| 305 |
THETAGAS
IMO 9368792
|
10,264 | 2008 |
23.2
|
E |
| 306 |
ECO CHIOS
IMO 9698367
|
5,878 | 2013 |
23.3
|
E |
| 307 |
GAS AEGEAN
IMO 9545209
|
10,390 | 2012 |
23.5
|
E |
| 308 |
SOPHIA KOSAN
IMO 9374557
|
10,343 | 2008 |
23.5
|
E |
| 309 |
ECO STREAM
IMO 9698355
|
5,872 | 2014 |
23.7
|
E |
| 310 |
CORINTHIAN
IMO 9746786
|
6,424 | 2015 |
23.8
|
E |
| 311 |
GAZ INTERCEPTOR
IMO 9291224
|
6,539 | 2006 |
23.9
|
E |
| 312 |
HELENA KOSAN
IMO 9342396
|
8,555 | 2007 |
24.0
|
E |
| 313 |
GAS HUSKY
IMO 9507764
|
7,218 | 2012 |
24.2
|
E |
| 314 |
GASCHEM ARCTIC
IMO 9371672
|
9,263 | 2010 |
24.3
|
E |
| 315 |
CORAL SHASTA
IMO 9254941
|
10,770 | 2003 |
24.4
|
E |
| 316 |
CORAL IVORY
IMO 9207039
|
6,875 | 2000 |
24.4
|
E |
| 317 |
HAPPY CONDOR
IMO 9368780
|
10,355 | 2005 |
24.9
|
E |
| 318 |
EPIC BORNEO
IMO 9519535
|
6,028 | 2010 |
25.1
|
E |
| 319 |
CHRISTOPH SCHULTE
IMO 9368778
|
10,309 | 2007 |
25.1
|
E |
| 320 |
NAVIS
IMO 9260366
|
6,017 | 2002 |
25.2
|
E |
| 321 |
CLAMOR SCHULTE
IMO 9220809
|
9,174 | 2002 |
25.4
|
E |
| 322 |
RHOGAS
IMO 9618848
|
8,611 | 2012 |
25.6
|
E |
| 323 |
SYN ANTARES
IMO 9512848
|
9,230 | 2014 |
25.7
|
E |
| 324 |
BWEK TENERIFE
IMO 9506198
|
7,879 | 2008 |
26.2
|
E |
| 325 |
GAS SPANAKOPITA
IMO 9232321
|
6,634 | 2001 |
26.3
|
E |
| 326 |
HAPPY PEREGRINE
IMO 9553660
|
14,995 | 2014 |
26.4
|
E |
| 327 |
DONATA SCHULTE
IMO 9624005
|
8,573 | 2013 |
26.7
|
E |
| 328 |
CGAS LION
IMO 9578036
|
4,995 | 2013 |
26.8
|
E |
| 329 |
CGAS JAGUAR
IMO 9578024
|
4,980 | 2012 |
27.0
|
E |
| 330 |
CGAS TIGER
IMO 9577991
|
4,986 | 2012 |
27.1
|
E |
| 331 |
GASCHEM BALTIC
IMO 9269269
|
9,157 | 2004 |
27.4
|
E |
| 332 |
ZETAGAS
IMO 9623984
|
8,641 | 2013 |
27.6
|
E |
| 333 |
CORAL PEARL
IMO 9425253
|
8,602 | 2009 |
27.6
|
E |
| 334 |
ECO NICAL
IMO 9746774
|
6,407 | 2016 |
27.8
|
E |
| 335 |
CGAS LEOPARD
IMO 9578012
|
4,986 | 2012 |
28.8
|
E |
| 336 |
CORAL PATULA
IMO 9425241
|
8,570 | 2009 |
29.3
|
E |
| 337 |
KUZGUNCUK
IMO 9235842
|
5,223 | 2001 |
29.8
|
E |
| 338 |
ECO DOMINATOR
IMO 9789532
|
5,891 | 2016 |
30.1
|
E |
| 339 |
DOROTHEA SCHULTE
IMO 9618862
|
8,643 | 2013 |
30.2
|
E |
| 340 |
CGAS PANTHER
IMO 9578000
|
4,994 | 2012 |
30.5
|
E |
| 341 |
KAPPAGAS
IMO 9215141
|
6,211 | 2001 |
31.0
|
E |
| 342 |
HAPPY PELICAN
IMO 9618850
|
8,610 | 2012 |
32.1
|
E |
| 343 |
ORINDA
IMO 9240122
|
9,352 | 2002 |
32.2
|
E |
| 344 |
BENRIACH
IMO 9658367
|
5,209 | 2015 |
32.7
|
E |
| 345 |
GAS NERO
IMO 9109316
|
5,599 | 1994 |
34.9
|
E |
| 346 |
CORAL LACERA
IMO 9350898
|
4,999 | 2006 |
36.4
|
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.