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 2024. 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 |
CGAS LION
IMO 9578036
|
4,995 | 2013 |
27.9
|
E |
| 302 |
DONATA SCHULTE
IMO 9624005
|
8,573 | 2013 |
27.9
|
E |
| 303 |
CGAS TIGER
IMO 9577991
|
4,986 | 2012 |
27.9
|
E |
| 304 |
MORITZ SCHULTE
IMO 9220794
|
9,174 | 2002 |
28.0
|
E |
| 305 |
RHOGAS
IMO 9618848
|
8,611 | 2012 |
28.3
|
E |
| 306 |
CGAS LEOPARD
IMO 9578012
|
4,986 | 2012 |
29.5
|
E |
| 307 |
KUZGUNCUK
IMO 9235842
|
5,223 | 2001 |
29.9
|
E |
| 308 |
CORAL PARENSIS
IMO 9208148
|
8,669 | 2000 |
30.5
|
E |
| 309 |
GASCHEM BALTIC
IMO 9269269
|
9,157 | 2004 |
31.5
|
E |
| 310 |
IVIS
IMO 9268394
|
7,496 | 2003 |
32.0
|
E |
| 311 |
ECO DOMINATOR
IMO 9789532
|
5,891 | 2016 |
32.8
|
E |
| 312 |
BENRIACH
IMO 9658367
|
5,209 | 2015 |
33.2
|
E |
| 313 |
ENIGMA
IMO 9103398
|
5,807 | 1999 |
34.5
|
E |
| 314 |
CORAL LOPHELIA
IMO 9350886
|
4,999 | 2006 |
36.8
|
E |
| 315 |
CORAL LEAF
IMO 9404625
|
4,999 | 2008 |
37.8
|
E |
| 316 |
OPTIMUS
IMO 9870472
|
3,629 | 2021 |
37.8
|
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 2024 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.